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Gallery, Projects and General => Project Logs => Topic started by: Bernd on October 01, 2009, 01:56:53 PM

Title: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 01, 2009, 01:56:53 PM
All right. I know I've got several projects pending here in the "Projects" page of the forum, but I really need to build this one. It's cold water that I need to go into to rescue my RC nitro powered speed boat when the engine dies way out in the water.

So I came up with the idea of building a rescue boat that has styrofoam pontoons. I haven't figured out what I'm going to use for the structure of the boat yet. That'll come as I go along since this will be a build while you engineer it.

SO first I need a set of templates and some foam. The templates are 1/4" luan and I'm using blue styrofoam just because I have a bunch of it. In the pic you'll also see the side profile templates. I made two so the cut would be parallel when cutting out the rake on the bow.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0001.jpg)

Here I'm taking the first cut on one side. Notice the small nails I'm using to hold the template in place.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0003.jpg)

Now for the inside. A hole is drilled to get the wire through and the inside is cut out.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0005.jpg)

The two halfs, one with a cut out and one without a cutout, are ready to be glued together using spray adhesive. This pic gives an idea of how wide this boat will be to capture the little speed boat and bring it back to the dock.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0008.jpg)

Here the side templates are being used to cut the curve of the bow.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0011.jpg)

And there we have it. The finished pontoons ready for a bit of detail work and adding fiberglass.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0014.jpg)

Regards,
Bernd

Title: Re: RC Rescue Boat built from Styrofoam
Post by: chuck foster on October 01, 2009, 02:09:24 PM
looking good stew  :thumbup:

i have what might be a very dumb question but is there not fumes from melting the foam???
if so i hope you are wearing a mask or something to protect your lungs.

chuck :wave:
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on October 01, 2009, 02:11:35 PM
Bernd

Well it looks like you have got a good start on it. Looks like you have been practicing with your cutting speeds and heat settings. You seem to be getting a pretty good cut.  :ddb: :ddb:

 Are you going to make any provisions for ice breaking in case the weather turns cold? :lol: :lol:

Cheers  :beer: :beer:

Don

Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 01, 2009, 03:59:07 PM
looking good stew  :thumbup:

Hey Stew. I didn't know you were building a boat just like me.  :lol:  :lol:  :lol:  :lol:

Sorry Chuck I just couldn't resist. You know how many times I did that too!  :bang:

Quote
i have what might be a very dumb question but is there not fumes from melting the foam???
if so i hope you are wearing a mask or something to protect your lungs.

chuck :wave:

The fumes are not that bad, I mean no big cloud. There are a few. A fan takes care of that.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 01, 2009, 04:03:31 PM
Don,

It's not as good as I would like it. I've found that the nichrome wire stretches when it gets hot. Looks like I'm going to have to modify the cutter a bit. Also want to try SS wire.

If it gets that cold I'm going for making an ice boat.  :lol:  Or I'll just stick with the steam engines and my model railroading and machine modds and ................   :D

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: sbwhart on October 01, 2009, 04:05:21 PM
looking good stew  :thumbup:

Hey Stew. I didn't know you were building a boat just like me.  :lol:  :lol:  :lol:  :lol:

Sorry Chuck I just couldn't resist. You know how many times I did that too!  :bang:

Quote
i have what might be a very dumb question but is there not fumes from melting the foam???
if so i hope you are wearing a mask or something to protect your lungs.

chuck :wave:

The fumes are not that bad, I mean no big cloud. There are a few. A fan takes care of that.

Bernd


:scratch:


The real Stew or is there more than one

Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on October 01, 2009, 04:16:33 PM
Don,

It's not as good as I would like it. I've found that the nichrome wire stretches when it gets hot. Looks like I'm going to have to modify the cutter a bit. Also want to try SS wire.

If it gets that cold I'm going for making an ice boat.  :lol:  Or I'll just stick with the steam engines and my model railroading and machine modds and ................   :D

Bernd

Bernd

I have seen that most people put a spring on one end of the nichrome wire to keep a uniform tension on the wire as it got hot and expanded. It can be a catch 22 situation. :bang: Too much or too little tension. Something else that would work is a pulley and weight system to keep tension on it.  :doh:

Cheers  :beer:

Don


Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 01, 2009, 04:35:44 PM
I already broke one wire after I shut the power off. :bang:

That's the one mod I'll need to make. Think I'll add a pulley and weight. More even tension that way.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 01, 2009, 04:37:17 PM

 

:scratch:


The real Stew or is there more than one



There's only one real Stew and you are the man.  :thumbup:   :)

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: sbwhart on October 01, 2009, 04:53:58 PM
Thanks Bernd

Nice boat build by the way I was bit puzzled as to how it would work but I can see now you catch the rescue between the hulls:- neat idea  :thumbup:

Have fun

Stew
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 01, 2009, 06:20:56 PM
Thanks Stew,

Well, that's the idea, catch it between the hulls. But when the boat is out there several yards (meter's?) it isn't going to be easy. Will have to video some of that for a good laugh, right?

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on October 01, 2009, 07:04:47 PM
Thanks Stew,

Well, that's the idea, catch it between the hulls. But when the boat is out there several yards (meter's?) it isn't going to be easy. Will have to video some of that for a good laugh, right?

Bernd

Bernd

If worst comes to worst you can always install video telemetry? Boy if your wife reads all these ideas that I keep having she is going to kill me. :lol: :lol:

Cheers  :beer:

Don

Title: Re: RC Rescue Boat built from Styrofoam
Post by: mklotz on October 01, 2009, 07:36:25 PM
Well, that's the idea, catch it between the hulls. But when the boat is out there several yards (meter's?) it isn't going to be easy. Will have to video some of that for a good laugh, right?

Wouldn't it be easier to put a high-strength magnet in the bow of the boat-to-be-rescued and a thin steel plate on the stern of the rescue boat?  Seems like a lot less fiddly way to take the disabled boat into tow.  Get close and let Maxwell's laws do the hard work for you.
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 01, 2009, 08:21:09 PM
Ah Marv. Were talking models here and don't need any great speed to get the boat back. Half the fun is in building this boat and then trying to get the other boat. If I wanted to make it easy I would have a small hook on the front of the speed boat and a large loop on the rescue boat that could be dropped over the hook on the speed boat. A lot less weight and I won't have to worry about the magnet letting loose when the water gets rough.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 02, 2009, 01:42:13 PM
Got a little more done on the Rescue Boat.

In order to mount a frame work over the top you need to secure that to the pontoons or floats. To have a secure mounting in the styrofoam you need to add some wooden blocks, perferably hard wood that will hold the screws better. So I need to make some cutouts in the floats. I marked them on using a felt marker.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0015.jpg)

Next is to scoop out the foam. Very easy to do if you have one of these:

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0018.jpg)

All you need to do is use some 12 or 10 gauge copper wire formed to the shape you want to cut out. In this case I needed something about a 1" wide.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0016.jpg)

Of course you don't want to stick the whole iron through the foam so a stop is needed. I made one out of a piece of 3/4" plywood. Cut two slots in to fit over the wire and presto a depth stop.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0017.jpg)

And here we have the scooped out 1" wide by 2" long by approx. 3/4" deep pocket.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0019.jpg)

Here are the blocks that are going to be expoied in. They are 1" X 2" X 3/4" hardwood. I ACC'ed small pieces of wood over the top so they would be level with the top of the foam.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0021.jpg)

Filled the hole full of epoxy.........

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0020.jpg)

.....and dropped in the blocks and taped them down so they wouldn't float to the top.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0022.jpg)

Next will be a super structure over the top of the two floats to tie it all to gether, but first I need to get the propellers so I know about where to mount the motors. They have been ordered and so have two 6 volt batteries the will power each of the motors. So it'll be a while befor I get back to this project. I figure the items should be here by next week sometime.

In the meantime I can think about what I'm going to use for the superstructure. It's going to be either real small PVC pipe or 1/4" luan. Right now I'm leaning toward the luan.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: rleete on October 05, 2009, 04:55:11 PM
Go with the PVC.  Make it look like that massive boat Howard Hughes built to steal rescue the sunken Soviet sub back in the 1970's.

Heh.  That just reminded me of something my wife said a while back.  I was watching a show on the TV about the Kursk - a Ruskie sub that sank due to accident, killing all the crew.  Named, of course, for that epic battle in WWII.


She walked in the room and said, "what did they expect, naming it "Cursed"?    :doh:
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 05, 2009, 06:15:03 PM
Gotta' make a trip over to Debbie Supply and see if they have any 1/4" PVC. I think that would work the best.

Your wife isn't blonde is she.  :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 11, 2009, 06:00:31 PM
Did a bit more work on the boat this past week. Today I got the props mounted to the motors. The story continues.

I tried to use electrical tape to hold the pieces of wood down. Didn't work to good.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0022.jpg)

I finally resorted to a couple of small nails.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0023.jpg)

After it all dried I sanded it down as best I could. I left a few scallops in the foam but some Bondo will take care of that.
Next will be to cover the floats/pontoons with fiberglass cloth and resin. First I need to save up some cash to buy resin. I plan on using West Epoxy to do the fiberglass.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/100-0024.jpg)

In the mean time I've turned my attention to the power system of the boat. I'll be using two 6 volt motors that came out of one of those child electric cars. They come with two pretty powerful electric motors.

I needed to make a couple of adapters to attach the props to the motors. A simple turning exercise. Since I'm doing this on the fly no drawing or dimensions are presented. Also each motor set could be different. I turned one end for a tight fit in the prop hole and the other for a press fit onto the shaft of the motor. Worked quite nice.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0001.jpg)

And here they are ready to have the motor mount designed. That won't happen till I get the superstructure built.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0002.jpg)

Until next time.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: ibuildstuff4u on October 11, 2009, 06:33:35 PM
I raced RC boats for a few years and always wanted to make a rescue boat but never got around to it.  Most of the time I lugged my little 14' boat along.

I like your design using the two pontoons, but I'm not sure about the power source to drive the boat.  The fan drives are not very powerful and I'm not sure they will be up to the job.  I had a nitro powered fan boat in the past with a .46 sized engine and a very light weight fiberglass hull.  We tried to use it to retrieve a stalled boat and it couldn't push it.  The stalled boat wasn't even full of water, and the fan boat couldn't push it.

I know it will take more work, but I think you will be much better off with an under water prop in each pontoon.  You can use a stick radio and set up the boat with two speed controls so you can drive the motors in different directions or at different speeds.  This way you can drive it like a tank and you won't need a rudder.  Most stick radios can be taken apart and the right side stick can be turned 90* so it moves the same direction as the left side stick. 

I know the two motors look like they move a lot of air, but that boat is going to be quite heavy when done and will take more power than that to move it's self not to mention a second boat that could be full of water from a crash.

Good luck on the build.  It looks good so far!

Dale P.
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 11, 2009, 10:36:46 PM
Thanks for the heads up Dale. Going to continue with the build just for the fun of it. If it dosen't work I can still redo it and use the motors to drive water props.

Besides, I need something to run around when I run out of nitro.  :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on October 12, 2009, 12:16:45 AM
Bernd

If you use bondo or any type of filler on the foam to smooth out the ripples it would be best to check it out on a piece of scrap first as most fillers will attack foam. I would hate to see all your hard work end up as just a blob.  :lol: :lol:

You probably knew this already but better safe than sorry.  :D

Cheers  :beer:

Don
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on October 12, 2009, 01:43:15 AM
Bernd

I have just been browsing and thinking (that can be a bad thing), when you go out to play with your RC boat you should invite boatmadman along. This would be good for both of you. You would have a means of rescue if needed and he would get the practise of flo/flo rescue.  :lol: :lol:

Just be sure to take a video of it all because  :worthless: and I think it might be a first. :)

Cheers  :beer:

Don
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 12, 2009, 10:56:29 AM
Don,

Oh ya I would definatly try it out on scrap. I discovered that the fiberglass resin I had does a number on foam when I tried to glue two pieces together. Perhaps I'll cover it with fiberglass first and then fill in "any" deformities afterwards.

All boatmadman has to do is show up at the river next season and he can have as much fun as I do.  :D BTW I've already got one guy interested in it and he finally bought the same kind of boat I have.

Vids are definatly on the list. Just need to train the other half how to use the camera in video mode.

Stay tuned. More to come.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 17, 2009, 12:23:05 PM
More work has been done on my rescue boat. I couldn't decide if I wanted to use wood or plastic tubing to build the super structure. A trip to the hardware store for something else was all it took. I found 1/2" CPVC tubing. The id is 1/2" and the od is 5/8". This tubing is used instead of copper 1/2" for plumbing. It is rated at 100psi at 180 degree F. It's used both for cold and warm water. Only problem was I had the wife's Beetle and an 10 foot long piece wouldn't fit in, plus they wanted way to much. So a trip to one of the Home Horror stores the next day got me what I needed. 4 pieces of 4 foot long pieces. They would definitely fit.

So on with the build. In order to mount the tubing I would need to fasten it to the wood blocks I had epoxied into the foam. I drilled a 1/2" hole for the dowels.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0003.jpg)

Next was to make up the first part of the super structure. The pipe has been cut to the varying lengths I needed and laid out with the 45 degree fittings.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0005.jpg)

A couple of cross members in the back to catch the boat.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0006.jpg)

The cross pieces had "birds mouth" cuts made in them so they would fit the mating pipes.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0007.jpg)

This is how I made the end cuts. I'm using a 5/8" end mill to cut the pipe. You have to take it slow or the cutter edge will catch the pipe and break it.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0008.jpg)

I made a quick jig to help align the two cuts.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0009.jpg)

Here I'm lining up the first cut so I can make the second cut on the other end.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0010.jpg)

Over all view of what I did in the pic above.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0011.jpg)

The first time I tried to hold the pipe in the vise the cutter pulled the pipe out of the vise. Not wanting to crush the pipe I added a piece of dowel into the pipe so the vise wouldn't crush the pipe when I tightened it up. Make sure the dowel is pushed in further, out of the way of the cutter, before cutting.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0012.jpg)

The back end dry fitted.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0013.jpg)

The front dry fitted.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0014.jpg)

And here's what the whole thing will look like when in the water bringing back the race boat with a dead engine. There's much more to do as far as the superstructure is concerned. I need to add a few more pieces of pipe yet.
(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/200-0015.jpg)


That's it for now.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: chuck foster on October 17, 2009, 12:45:49 PM
looking good bernd  :thumbup: :thumbup:

chuck  :wave:
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 17, 2009, 02:38:29 PM
Thanks Chuck

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on October 17, 2009, 02:45:10 PM
Bernd

Starting to look good. One thing that you may want to keep in mind is that sometimes these boats flip over so may not present the same profile to the rescue boat.  :lol: :lol:

Cheers  :beer:

Don
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on October 17, 2009, 04:52:09 PM
Bernd

Starting to look good. One thing that you may want to keep in mind is that sometimes these boats flip over so may not present the same profile to the rescue boat.  :lol: :lol:

Cheers  :beer:

Don


Yeh, I know. But the width dosen't change. Just the top to bottom. Trouble is I stall it more than flip it over. I take it easy in the turns until I get the feel of just how much I can push it.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 09, 2010, 07:30:57 PM
More progress to report on building my rescue boat.

I've got the super structure done and started on designing the motor mounts.

Here's a pic of the finished super structure.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0001a.jpg)

Here's what the finished motor holder will look like.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0001.jpg)

First a wooden plug needs to be turned.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0002.jpg)

The wooden plug and the PVC pipe that it fits into. This will keep from crushing the PVC pipe when tightened in the chuck.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0003.jpg)

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0004.jpg)

Next the inside of the PVC gets bored out for a snug fit of the motor.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0005.jpg)

Test fitting the motor.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0006.jpg)

Both motor holders bored out and the motors installed.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/300-0007.jpg)

Next the PVC pipe needs to get fastened to the wood so they can be mounted on the boat. Also a cover needs to be made for the end to bolt the motors into the PVC. That's next.

That's it for now. I really need to get this done before April when we'll be back at The River.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on January 09, 2010, 10:49:14 PM
Bernd

Glad to see that your back at the rescue boat Bernd. It's been a while but spring is just around the corner.  :lol:  :lol:

Next thing I know you will be telling me your working on the cupboards!!  :lol: :lol:

Your off to a good start in 2010. All that procrastination is behind you now.  :ddb:  :ddb:

Cheers  :beer:

Don
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 11, 2010, 09:32:42 AM
No Don I look at it as having a whole year of procrstination ahead of me.  :lol:

Actually I'm trying to "multi-task", whcih I tell the wife can't be done, by also working on the cupboards. So far it's "almost" working.  :lol:  :lol:  :lol:

Bernd (who needs to think of what to do next)
Title: Re: RC Rescue Boat built from Styrofoam
Post by: raynerd on January 12, 2010, 02:45:22 AM
Hi Bernd, I didn`t see this one back in October. Nice build, I look forward to reading more about it!

Chris
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 12, 2010, 08:57:12 AM
Chris,

Thanks. It gets worked on as the spirit moves me.  :poke: But then that spirit seems to be napping as much as I am latley.  :lol:

But will need to have it done before spring.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on March 03, 2010, 10:53:25 AM
Bernd

I hear that the ice is melting in the St. Lawrence! Will you be ready to go boating? How is the Multitasking working out? Oh, I almost forgot

 
:lol: HAPPY BIRTHDAY :lol:

Cheers  :beer:

Don
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on March 04, 2010, 09:29:27 AM
Frist thanks for the birthday wish. Now I wish they wouldn't come so fast.  :lol:

Ah yes the rescue boat. Wellll.................I haven't done a thing with it latley.  :coffee:

I need to cover it with fiberglass, mount the motors, get a radio, wire it up, in general I just need to finish the dam thing. Might get it done by "NEXT" spring at the rate I'm going.  :(

To many other  :proj: to interfere with the boat project.  :bang: :bang: :bang: :bang:

But thanks for asking.  :thumbup:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: madjackghengis on March 09, 2010, 10:20:05 AM
I already broke one wire after I shut the power off. :bang:

That's the one mod I'll need to make. Think I'll add a pulley and weight. More even tension that way.

Bernd
Hi Bernd,  I thought I'd see what you were up to, and I would weigh in with the pulley and weight, as it is even, and easily adjustable for exactness.  I don't think you'll find anything that comes close to the reliability of the nichrome wire, I haven't worked with it in years, but decades ago there was nichrome, and then there were all the other wires that failed.  All in all, sounds like a good idea, I've helped a few people rescue a "dead in the water" r/c boat, and it isn't always easy. :poke:
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on March 10, 2010, 09:45:46 AM
I don't think you'll find anything that comes close to the reliability of the nichrome wire, I haven't worked with it in years, but decades ago there was nichrome, and then there were all the other wires that failed. 

I've read on some boat and airplane forums where they've used stainless steel  or just plain wire to cut foam. So I don't know. I'll stick with the nichrome.

After I wrote up a how to build it I discovered how many there were out on the net with a much better desing than what I had built. Oh well.

Quote
All in all, sounds like a good idea, I've helped a few people rescue a "dead in the water" r/c boat, and it isn't always easy. :poke:

The wife doesn't like swimming in water when it's only 40 to 50 degress water temp.  :( So I had to come up with something. Now I need to get back at it becasue in another month we'll be getting ready to open the cottage up at the Islands.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: madjackghengis on March 10, 2010, 11:40:46 AM
Bernd,  it's funny, my wife won't even consider diving in when the water at that temperature, no matter what I offer in return, either, do you think its something about us?  She would stand on the bank and laugh at my attempts to rescue things myself though, and give me "the look", if I were to scowl back at her at that.  All in all, looks like the project is coming along well, I hope the "wind power" works, but resorting to blades under water isn't so bad if it doesn't.  If I didn't have so many projects already, living on a creek which always has water in it, and sometimes ten or twelve acres of my land in it as well, I ought to put together a boat project, one that doesn't involve a twelve foot aluminum boat, and a pole.  In that one, the water moccasins were faster than I could pole, and they aren't afraid of people. :headbang:  Mad Jack
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on July 09, 2010, 07:38:05 PM
Bernd

Seeing as its now the new boating season I was just wondering if you had an update for us?  :lol:

Cheers  :beer:

Don

Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on July 10, 2010, 08:54:47 AM
Don,

I see your going though the projects and seeing who hasn't finished their work.  :poke: :poke: :lol: :lol:

To make a long story very short, Nope I haven't worked on my boat at all. New developments. My Dad past away here back in early June so I've been comforting my mother. Plus have been working on the inside of the house to get the rooms done. The hobby has kind of taken a back seat for now. Even turned down some paying jobs because of time contraints.

Hope to get back into it sometime come the cold season. Also got a new outdoor toy I need to take a pick of and post. It's a great play thing.

Right now as I write this I'm up in the 1000 Islands on Saturday. Will be returning tonight for a memorial for dad given by my daughter Sunday.

So that's about they way it's been for this year. I need to get busy and finish some of those projects I've started before you  :poke: to much and I have balck and blue spots all over me.   :lol: :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on July 10, 2010, 12:37:09 PM
Bernd

I am so sorry to hear about your Father. My condolences to you and the rest of your family. That certainly explains why you haven't been as active for the last couple of months as previous.

Yes, I started going back through the old files trying to generate some posts and replies to dead or dormant projects. It seems to be working but time will tell. Sometimes it brings unexpected answers.

Sometimes life gets in the way of your hobby but that's just a part of it all. Hope that you get a bit of relaxation up on the river and as long as you look after your Mother I won't  :poke: to much about unfinished projects.

Be well Bernd and enjoy peace and quiet on the river (when the big boats are out playing). :D

Cheers  :beer:

Don

Title: Re: RC Rescue Boat built from Styrofoam
Post by: Rob.Wilson on July 10, 2010, 01:05:52 PM
hi Bernd

My sincerest condolences to you and family


Rob
Title: Re: RC Rescue Boat built from Styrofoam
Post by: doubleboost on July 10, 2010, 01:25:56 PM
Hi
Bernd
My deepest condolances on your loss , i have just lost my brother so i realise what a dificult time you are going through
Regards
John
Title: Re: RC Rescue Boat built from Styrofoam
Post by: AdeV on July 10, 2010, 03:50:15 PM
Bernd,

I agree with what Don, Rob & John say; the client who pays me most of the money I need to keep me in my hobby unexpectedly lost his dad last year, it was hard going on him.
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on July 11, 2010, 10:37:32 AM
Thanks guys. I appreciate it.

Thing is dad was into live steam also. Now I've got a couple of steam launches to play with. I'll take a couple of pics of them and post. He also left behind a few finished engines that I'll post pictures of once I get all the important personal stuff out of they way.

And he was an avid model airplane modeler and flyer. I see a few engines that I can built a swamp boat out of.

Untill then I'll keep looking in here to make sure everybody behaves.  :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on August 11, 2010, 08:04:47 PM
Spent last weekend up at the Islands. The Poker Runs America had it's poker run on Sat. Lot's of noise.

Ya, I know were's the video's. Between the wife and I we only have one digital and she was using it, after all it is her's.  :D

Anyway, I've had one of thos "Ah ha" moments. I discovered why I'm so slow in getting this boat in the water. Here's why. I had already seen the finished boat in my mind. All nice looking and everything. Everybody  :bow: to me to tell me how nice it looked. Then it hit me. This boat is supposed to be functional, not pretty. Once I got that out of my head I made some progress. And I'm here to tell you what I did. May not be much but it'll have to do for now. Besides I'm starting to hurt where Don keeps  :poke: me.  :lol:

So here's what got done.

I had origanlly made the screws that hold the prop on out of aluminum and have a 5-40 thread on it. Quite small. While starting up one motor the screw self tighten to the point it sheared off. So I made a new one from some printer shafting and added a brass washer.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/400-0001.jpg)

I finally came up with a platform to hold the motor's on. The tie wraps are temporary.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/400-0002.jpg)

Here they are both mounted. Now I can start thinking about the air and water rudder's.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/400-0003.jpg)

As I had stated the motors came from one of those kid's Battery powered vehicles. Here's what the harness looks like. Now all I need to do is lenghten some of the wires.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/400-0004.jpg)

So I've made some progress. If the wife finds out I'm not working on the house I could be in big trouble. But I'll never tell, she's on vacation at the cottage. Maybe tomorrow I will do a bit to look like I've been working on the house, NOT.  :ddb:

Bernd

Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on August 11, 2010, 10:49:18 PM
Bernd

Looking good. I promise that I won't kick you any more for a while in order to let you heal so that you can give this your full undivided attention. I have noticed a couple of other little references in a few of your other posts but I thought I would lay off picking on you for a while. I just had to say that so you didn't think that I didn't care any more. :lol: :lol: :lol:

I just hope that you don't have to use this to rescue your other rescue boat.  :lol: :lol: :lol:

Cheers  :beer:

Don

Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on December 22, 2010, 09:52:14 PM
Well with spring just around the corner I thought I'd better get busy and finish my air powered rescue boat.  :lol:

I was going over some of my "round-tuit" list and found I need to get this project finished this year before the boating season starts up at the River. It's only 4 months  away before the water gets turned on in the camp.

So with out further long winded explanations I start with some pictures I took back in September.

I already had the wooded platform screwed to the frame. Now the motors needed to get mounted to the platforms. That was done by making a couple of wooden cradles for each motor and gluing them on to the  platform.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0001.jpg)

Next the motors needed to be strapped to the cradles. I used a piece of copper wire to determine the length of brass rod I would need.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0002.jpg)

A pic without the motor.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0003.jpg)

Next a piece of brass rod was cut to length and thread 2-56 at both ends.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0004.jpg)

The center line of both the brass rod and pipe were determined and marked.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0005.jpg)

The brass rod was lined up and clamped.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0006.jpg)

It was then bent into a "U" shape around the pipe.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0007.jpg)

The motor was mounted and the rod checked for fit.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0008.jpg)

A piece of aluminum was added so the nuts wouldn't be pulled through the wood when tightened.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/500-0009.jpg)

That's were the boat stands now. It will need to get some holes and dents filled in with some auto body puty and then it will be covered with fiberglass cloth. Might even get a paint job. ::)

I still need to buy a radio for it and work out the steering of the rudders. I've also found an electronic drive that I'm going to use for controling the motors.

That's it for now.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bogstandard on December 23, 2010, 03:35:54 AM
Bernd,

I don'r want to piddle on your parade at such a late stage, as you are getting on so well with it.

It was mentioned very early on in the post about the power of your motors.

I have seen a lot of variations of your design over the years, all geared towards being a rescue boat, and very few have succeeded, mainly because they were grossly underpowered, as I think yours will be.

You can very easily get into a catch 22 situation, in fact, I think you are already in it. The motors you have will be lucky if it actually moves the rescue boat at all, mainly due to your battery weight. So you then go for larger motors, which then require heavier batteries to give you the amps to run and for duration to actually rescue something - catch 22.

I would suggest you have a word with Peter (HS93). He is a big fan of brushless motors, whereas it is a little after my time, I am still stuck with your 'old fashioned' motor technology, and I personally think that is the way you need to go to give you a lot more power without the gain in weight.

Just a suggestion


Bogs

Title: Re: RC Rescue Boat built from Styrofoam
Post by: HS93 on December 23, 2010, 06:10:14 AM
If you want any info let me know , you will find it a lot sheaper than brushed and good deal more power and much lighter. the motors you have will never push it with a dead boat in as they always tend to try and go sidways in jaws type recue boats.

Peter
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on December 23, 2010, 09:07:46 AM
John,

Your not going to piddle on my parade. If it works fine if it dosen't, oh well. Like Edsion said, he found out 100 different ways how not to make a light bulb.

I see were your going with the catch twenty two. The only reason I'm using air props is the occasional seaweed that gets hung up on the props.

You don't mind if I try to prove you wrong do you?  :D

HS93,

I've seen all the latest on the lipo batteries and motors.

I'm just having a bit of fun here by trying to use some surplus stuff and throwing it together to see if it'll work. If it dosen't then I guess I'll have to build a steam powered boat for the following year.

Thanks guys. Appreciate your input, but being the block head I am, I'm going to continue. You guys have the reserved right to tell me "I told you so" later. :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bogstandard on December 23, 2010, 12:24:05 PM
Bernd,

I would love it if you prove me wrong, then you can say 'I told you so'.


John
Title: Re: RC Rescue Boat built from Styrofoam
Post by: HS93 on December 23, 2010, 07:57:54 PM
who said li pol's ?   they work just as well on gell cells.

peter
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on December 24, 2010, 08:14:27 AM
Peter,

I've been following an airboat forum and they use the brushless motors and lipo cells. These guys are going for speed. One has reached 98mph. All you see is a streek across the water. To me that's not much fun. I like it slow and easy. Comes with age you know. :lol:

I've looked at all that new tech stuff in electronic controls. Really fascinating stuff, a bit expensive too.

I'm going to keep going with this. I just have to prove Bog's wrong or right.  :lol:  :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: madjackghengis on December 27, 2010, 11:13:32 AM
Hi Bernd, I was just going through and looking at old posts, my condolences on your Dad passing, I wasn't able to get to my parents for Christmas, and my Mom is not doing well, so I know it hits hard.
    Regarding technical things, nicrome wire is in fact a stainless steel, just a very special one, designed for heat, so it won't be bettered by ordinary stainless wire.  I hope you get enough power out of your motors, but if not, you can always change over, the brushless ones are substantially more efficient.  Spring is getting closer every day.  All in all, it either works, or you just have to work on it more, until it does, so keep shuffling forward. :poke: mad jack
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on December 27, 2010, 01:07:49 PM
Thanks Jack,

Mothers first Christmas was a bit tough on her but she survived. Plus she's going to be a great gand ma, so that cheered her up a bit.

As far as the motors go. I think they'll be powerful enough. They just about push the boat across the table now. Next would be to try a bigger prop. It doesn't take much to push a boat through water. We'll see come spring time.

Just need tofigure out a way to mount the air rudduers onto the back. Need to get a radio too. Gives me something to work on between doing the molding in the house. :)

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: madjackghengis on December 29, 2010, 08:20:29 AM
Hi Bernd, it's good to know there is something happening with your mother that is upbeat, attitude will keep a person alive when lack of anything to look forward to leads to depression, it's good to hear she's about to become "great grand-ma", and that she got through Christmas all right.  I just got a call from my mother last night, and she's past the pnumonia and doing better, so I'm much relieved.
    It's also good to see you back on the boat, I suspect you will try many motors before you're done, unless what you've got does just what you had in mind, in which case, why change what works?  with regard to the steering of the air, have you considered a "quarter moon shaped or "C" shaped sheet aluminum piece, around the motors, with the tips of the "C" being the pivots for the rudders, and the body of the "C" being an air guide to reduce the turbulence sure to be generated?  That would put the needed bell crank either above the motors, or beneath them, and out of the airstream, reducing interference and giving a solid mount for the "rudders".  I've seen similar on air boats used in Florida, and out here in the swamps of North Carolina.  I haven't done anything with such things, but a lot of emphasis seems to be put on guiding the airflow into the blades as much as there is in the rudders.  Aerodynamic nacelles for the motors would let the air move more efficiently, and reduce turbulence, which is probably as important for power as the motor design its self.  I don't know much about air boats, but I spent a long time around helicopters, and they tend to give one a good amount of respect for turbulence, given the work done, and the slow speed it gets done at.  I hope this adds a bit to think about at least.  Other than that, you're looking good, and with some time before spring.  :headbang: mad jack
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on December 29, 2010, 02:27:27 PM
Thanks for the kind comments Jack. Things are looking up.

As far as the rudders are concerned. I think aluminum might be a bit to heavy for the back end. I's gotten a piece of 1/32" out in the shape to cover the whle blade length and it would get a bit to heavy with two. Thinking of going with a 1/8" foamboard cover with epoxy to water proof. Will see.

Haven't done much since I last posted the pics. Been a bit on the down side. Recovering though. Lot's of post op deppression to work through. Been there once.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: HS93 on December 29, 2010, 03:55:06 PM
A qiuck tip re your motors you need to open up the holes on your motor mount tubes by the brush gear they act as an aid to cooling in your case the air will come in the slots at the front and go out the holes by the brush, if you dont you may find your motors get hot, Just look at comercial motor mounts they always go to the trouble of cutting them out  for the front mounts.

peter
Title: Re: RC Rescue Boat built from Styrofoam
Post by: madjackghengis on December 30, 2010, 09:44:34 AM
Hi Bernd, just a thought, with weight your concern, some 1/32 balsa covered with plastic sheet or a doped finish is about as light as it gets, and is quite stiff and strong for the weight.  It's kind of funny, with all the advances in science, the same materials that were best for modelling fifty years ago, still are stiff competition with modern materials. Jack
Title: Re: RC Rescue Boat built from Styrofoam
Post by: rleete on December 30, 2010, 12:18:26 PM
Thin epoxy with acetone (I got a quart at the auto parts store for less than 3 bucks) to make it runny.  About 50/50, the mixture ratio is not critical.  Paint it on any wood, and it soaks in.  Let it cure (a couple of hours for the standard 5 minute stuff), and it's rock solid as well as impervious to mosture.
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on December 31, 2010, 10:06:40 AM
HS93,

Nice catch. I pulled the motor out and sure enough there are vent holes by the brushes. Even has blades for a fan effect. Nice project for a rotary table on the mill. Thanks.

Jack,

Good idea about the balsa. Never would "wood" have thought of that.  :lol:  I'll have to look and see if I got two pieces big enough.

Roger,

I went and spent a large sum this past summer on the "West Epoxy System" stuff. I bought some of that thin stuff that fixes dry rot on boats. I had to do some repair on my mom's house windows. So I have a bit left over might try that with Jacks iddea of balsa wood.

Thanks guys. All great tips and are going to be considered. Will let you know what happens as the spirit moves me. Right now I can't find the dam thing. :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: madjackghengis on December 31, 2010, 10:17:48 AM
Well Bernd, it seems like all the advise fell into place together, and that epoxy/acetone idea sounds much stronger than the old material with dope way we did it forty years ago, when we were kids.  When you find it, you will remember why you put it there, but not until then, I bet.   :lol: jack
Title: Re: RC Rescue Boat built from Styrofoam
Post by: HS93 on December 31, 2010, 10:48:52 AM


this may help you as well very light and works well.

http://www.rcgroups.com/forums/showthread.php?t=329811

Peter
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 02, 2011, 04:04:53 PM
A bit more progress on the rescue boat.

First pic is of the boat with both motors and both batteries on board. I weighed the boat with these on and it came in at 7lbs. Not bad.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0001.jpg)

Now as HS93 mentioned that I would probably need vent holes by the brushes. The next several pics depict how it was done. The motor has 4 vent holes and small straight blades to blow air out of the vent holes.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0002.jpg)

In order to cut the vent holes in the right spot I made a jig out of a piece of paper. The line on the paper represents the step in the plastic pipe to keep the motor from being pushed out the other side.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0003.jpg)

The paper is wraped around the out side of the motor with the pencil line just even with the body of the motor.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0004.jpg)

Then taking the side of the pencil I rubbed the area where the opening should be.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0005.jpg)

I then used a sharp hobby knive and cut out the opening in the paper.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0006.jpg)

I cut three of the four openings out. I figured the fourth would be covered by the wood cradle holding the motor anyway.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0007.jpg)

The paper was then taped to the plastic motor pod.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0008.jpg)

Now since the od of the motor is smaller than the od of the plastic pipe I was left with a gap. Not to worry.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0009.jpg)

The middle slot of the three slots was cut first. The other two slots were cut using the "close enough" method since they would not come out at the same place as the ones on the motor.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0010.jpg)

Another view of the middle slot after cutting with a cob mill.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0011.jpg)

Here you can see were the "guesstimate" came into the picture. I milled through at about mid point and then made the slot longer toward the needed side.

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0012.jpg)

And there we have it the motor mounted with the slots in the motor pods. I could have added the fourth slot since it woun't be coverd by the wood, but feel the motor has enough air getting at it

(http://www.kingstonemodeleng.com/ModelAirboat/RescueBoat/pics/600-0014.jpg)

HS93, I hope this works. Thanks again for the tip.

Now it's on to the rudders. I found a length of 1/8" thick, by 4" balsa. I cut out two rudders about 8.5" long. Now I have to "engineer" the assembly that will hold the rudder's on. Stay tuned while I order some material in the mean time.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: dsquire on January 02, 2011, 07:10:12 PM
Bernd

Happy New Year.

Looking Good. Looks like you have a good start for the new year. I guess I won't need the prod stick  :poke:  this year by the looks of it since you are getting such an early start.  :lol: :lol:

I hope that you realize that you may have as much fun with the rescue boat as you do with the regular boat. Kind of like the kids with a new toy and then end up playing with the box it came in.  :D :D :D

Cheers  :beer:

Don
Title: Re: RC Rescue Boat built from Styrofoam
Post by: HS93 on January 02, 2011, 08:56:49 PM
I use a lot of plasticard and drip a small amout of water especialy when drilling small holes  stops it melting good when using a scroll saw as it stops it sealing itself to the blade.this is the sort of thing I do with it


Peter
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 03, 2011, 10:11:12 AM
Well Don I'm glad you won't be  :poke: me. I'd turn all sorts of black and blue from the meds I take.  :D

Ya, it does look like I've had a good start on it this year. I hope I can keep the "steam" up to get it done. Also know what you mean about a new toy and wanting to play with that.

HS93 I ran the mill at a slow speed. Really didn't have an issue with plastic melting. I think the main problem was a dull cutter.

Sorry can't help ya with the picture problem. Maybe Eric can explain or somebody with more geek knowledge on computers than me.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: DavidA on January 03, 2011, 10:29:14 AM
HS93,

...I tried to upload some picture but I was told it was FULL so no more uploads they where only 131KB...




This is the same problem I'm having.

I don't know if it is relevant but I'm using Firefox as my browser.

Can anyone help ?

Dave.
Title: Re: RC Rescue Boat built from Styrofoam
Post by: DavidA on January 03, 2011, 10:41:38 AM
Interesting that there have been a lot of pictures posted after I started having the problem.  And most of them seem to be via Photobucket.
I wonder if it is only the direct postings to madmodder.net that are effected.

Dave.
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Brass_Machine on January 03, 2011, 11:37:09 AM
HS93,

...I tried to upload some picture but I was told it was FULL so no more uploads they where only 131KB...




This is the same problem I'm having.

I don't know if it is relevant but I'm using Firefox as my browser.

Can anyone help ?

Dave.

Fixed. The attachments folder was full. I just made it bigger...
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Brass_Machine on January 03, 2011, 11:41:50 AM
Interesting that there have been a lot of pictures posted after I started having the problem.  And most of them seem to be via Photobucket.
I wonder if it is only the direct postings to madmodder.net that are effected.

Dave.

Yup... when you attach pictures, you upload them to the server. When you use photobucket, they are only 'linked', so it doesn't use any space on the server.

All fixed now. The attachment folder was full :palm:

Eric
Title: Re: RC Rescue Boat built from Styrofoam
Post by: DavidA on January 03, 2011, 06:49:36 PM
Thanks Eric.

I have moved some of  my pictures to photobucket.

Dave.
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 03, 2011, 07:30:33 PM
Nice looking boat HS93.

What are the stats, length, widith,etc. ?

Now the big question, what kind of power to make it go through the water?

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: picclock on January 04, 2011, 06:10:35 AM
Hi Bernd

Nice looking boat - should be a beauty - looking forward to the finished pictures.

FWIW I'm with the others as far as propulsion goes, but with the correct 'impedance matching' it could be good. The motors you have are powerful but fairly low speed - they are designed that way for kids vehicles. To get a good match with the propellers should probably be large and if possible 4 bladed. Failing that a gearbox to increase the propeller speed may be the answer.  If they are like the ones my kids quad bike had they draw about 12A in use (~ 6 amps per motor). You can check what the original current draw was by knowing the battery Amp Hours (mine were 17) and how long the batteries lasted. From that you can find out if the motors are loaded correctly by measuring the current drawn.

The heat problem with the motor is significant as if its too hot the magnets tend to weaken. At the moment I can't imagine them getting hot at all because of the low load placed on them by the propeller. 

The foam cutting problem is a pain, and although I can get it good enough for my stuff I've never been really successful. I think the problem stems from the fact that differing thermal loads on the wire cause overheating at the edges. In the centre of the foam most heat is conducted away from the wire, this causes the resistance of the wire to fall exacerbating the problem. At the edges the heat is thermally conducted from the unused piece of wire to where the wire is in contact with the surface of the foam thus making that part of the wire hotter. FWIW I found the best results with a guitar string. The frame was H shaped with the cutting wire on top of the H and tension applied with a spring and string on the bottom. The cross bar of the H swivelled.

Just my 2 cents worth - please feel free to ignore.

Best Regards

picclock

Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 04, 2011, 08:50:56 AM
Information all gladly recieved picclock. You never know when somebody might find an answer inside one of these disscussion.

The motor's came out of a juncked toy. Can't remember the amperage. At 12 volts the motors with prop pull round 18 to 20 amps. I plan on driving the motors with a pusle widith modulation drive. Something I found in a robotic book on developing drives for robots. They've got drives up to 50 amps in there. I've ordered the parts and should have something running buy neek week I hope.

One major purchase left and that's a radio. Been loking around. Looks like Tower Hobby has the best and most.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: madjackghengis on January 04, 2011, 11:23:41 AM
Hi Bernd, I just wanted to say, Mauser Electronics has some kits for pulse width modulator motor controllers that are easy to build and pretty cost effective.  They used to be "Vellman Kits", but went the way of so many other kits.  So far that "rescue boat" is coming right along, I'm looking forward to seeing how you do your rudders, both in the water and behind the props.  I'm wondering if you've got enough battery power for the whole thing though.  I'd hate to see you have to change over to steam or gas power :poke: mad jack.  By the way, do you still have snow down there?  :lol:
Title: Re: RC Rescue Boat built from Styrofoam
Post by: picclock on January 04, 2011, 11:54:02 AM
Hi Bernd

If your motor is drawing 20 Amps that's 240W (1/3rd Horsepower) which should make it get fairly warm  :bugeye:. With two it should be very impressive.

For some reason I thought they were from a ride on kids toy  :hammer:.  PWM should work great for that.

Takes me back to my RC boating days where an electric speedboat of mine had a water pickup under the hull ( a bit of brass tube ) which wrapped around the motor to keep it cool, then discharged the water overboard. Built if for my kids  ::)  and the pushchair was useful for transport as well  :ddb: .

Good Luck

picclock




 
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 05, 2011, 09:17:02 AM
Hi Bernd, I just wanted to say, Mauser Electronics has some kits for pulse width modulator motor controllers that are easy to build and pretty cost effective.  They used to be "Vellman Kits", but went the way of so many other kits.  So far that "rescue boat" is coming right along, I'm looking forward to seeing how you do your rudders, both in the water and behind the props.  I'm wondering if you've got enough battery power for the whole thing though.  I'd hate to see you have to change over to steam or gas power :poke: mad jack.  By the way, do you still have snow down there?  :lol:

I want to try and scratch build that PMW out of the robotics book. If it works great if it don't oh well. Got the 1/8" stainless I ordered so will start on getting the rudders mounted. Not sure if I'm going to go with water rudders yet. Might wait to see hoe it reacts in the water first.

SNOW, what's that. 20 miles south of Rochester we were without snow on New Years day. Just got a bit here the last couple of days.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 05, 2011, 09:20:59 AM
Hi Bernd

If your motor is drawing 20 Amps that's 240W (1/3rd Horsepower) which should make it get fairly warm  :bugeye:. With two it should be very impressive.

I'm guesstimating on this becasue it sent my 10amp meter right off the scale and it flashd 18amps.

Quote
For some reason I thought they were from a ride on kids toy  :hammer:.  PWM should work great for that.

They are from one of those kiddy ride toys. These are quite big motors. A bit bigger around than a "D" cell battery. Perhaps I should take a picture for comparison.

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: picclock on January 05, 2011, 07:00:12 PM
Hi Bernd

Something doesn't sound quite right if they are those motors  :scratch:, and the size you say sounds about right. 20 Amps is really too much for a motor of that type - I would think even 10 Amps is a lot for a single motor. Looking at the ride on car ads they seem to indicate motor powers of <40W which equates to <4 Amps. I am pretty sure the one my kids had was more than that (possibility of corrupt memory here) so I may be wrong.   

If you look at the ride on toy gearing you can relate that to the correct motor speed assuming a speed of 5mph for the toy. If I remember correctly the motor drive to the wheels on my kids one was with a toothed belt and a reduction gear - but it was a few decades ago. I would estimate that at around 30:1 which would only give a motor speed of around 2-3000 rpm.

Stupid question but - when you measured the current were the meter leads plugged into the high current sockets on the meter ? (forgive my impertinence for assuming that you wouldn't do it that way). The other question is do you know what the off load (no prop) motor current is ?  My guess is it should be < 1 Amp.

When you make your PWM controller two things to look out for. Before the motor starts turning the current is only limited by the winding/brush resistance and the pulse width/inductance rise of current. So either large current FET's or ones that have a built in current/thermal limit. Before rotation the back emf of the motor winding causes a large current to flow through the flyback or commutation diode which should be rated to handle it. Failure of either of these components will likely cause smoke and flame if your batteries are up to it :zap:  .

Looking forward to seeing the project completed.

Best Regards

picclock

Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 05, 2011, 07:41:29 PM
Hi Bernd

Something doesn't sound quite right if they are those motors  :scratch:, and the size you say sounds about right. 20 Amps is really too much for a motor of that type - I would think even 10 Amps is a lot for a single motor. Looking at the ride on car ads they seem to indicate motor powers of <40W which equates to <4 Amps. I am pretty sure the one my kids had was more than that (possibility of corrupt memory here) so I may be wrong.   

I guess I better fess up and tell you what I'm doing. Both motors are from one of those toys. Can't tell you right now what it came out of but is was a bigger toy. There is an in-line fuse with a rating of 35AMPS, It's one of those car fuses. The motor's are actually run on a 6 volt battery, two of them to be precises. The motor's were set up for two speeds, fast and slow. I think the fast gave 8 volts at the motors. I'm going to run them on 12 volts since I don't have the friction I would if they were in the toy hauling a kid around. I've also run them for some time on this high voltage and they didn't get very warm.

As I said before, this is an experiment in fun. If it works great, if not I had fun building it and designing it.

Quote
Stupid question but - when you measured the current were the meter leads plugged into the high current sockets on the meter ? (forgive my impertinence for assuming that you wouldn't do it that way). The other question is do you know what the off load (no prop) motor current is ?  My guess is it should be < 1 Amp.

Not at all. The meter will only read up to 10amps. At 12 volts with the prop attached the meter flashed 18amps. So I'm guestimating.

Just checked it with no prop. Motor pulls about 6amps at 12 volts, so we're looking at 72watts free wheeling. Here's some motor dimensions. 65mm long, 45mm dia. permanet magnets.

The FET's I've ordered are IRF540 rated at 27 amps. If it burns those out I'll have to get one's with a higher amperage rating. Looking at using a 25 amp fuse

Quote
Looking forward to seeing the project completed.

Best Regards

picclock



Electrical parts are on their way here from Kallyforina. Should be here next Tuesady. I think I could have driven out there, picked them up and got back before then. Oh well that's what happens when you don't get next day air.  :lol:

Bernd
Title: Re: RC Rescue Boat built from Styrofoam
Post by: picclock on January 06, 2011, 03:49:15 AM
Hi Bernd

That makes more sense.

"Just checked it with no prop. Motor pulls about 6amps at 12 volts, so we're looking at 72watts free wheeling. Here's some motor dimensions. 65mm long, 45mm dia. permanet magnets."

With 72 Watts in the motor under no load it sounds like the motor core is saturating (too many volts). With all due respect, I can't see a motor of that size lasting long under those conditions. The size and description of the motor sound the same as the one for my kids ride on Quad bike - I could ride on it and often both my kids and a neighbours child would all clamber on it and ride around the garden. A very good toy. However I'm pretty certain the motors on mine were 12V (2x17Ah 6v red batteries if I remember correctly - would run for about 1 1/2 hours in continuous use).

With a 35A fuse I'm guessing around 100 Watts per motor in original use. If you want them to last long enough to retrieve your boat run them off 6 volts and up gear the prop (and/or 3-4 blade big as you can get prop).  If you can get the motor to use 10 - 15A at 6V with gearing/prop sizing this will allow the motor to run in its sweet spot allowing most of the battery power to be used for propulsive force, as opposed to heating and knackering the motor.

Good luck and best wishes for the project.

picclock









Title: Re: RC Rescue Boat built from Styrofoam
Post by: Bernd on January 06, 2011, 10:16:38 AM
With 72 Watts in the motor under no load it sounds like the motor core is saturating (too many volts). With all due respect, I can't see a motor of that size lasting long under those conditions. The size and description of the motor sound the same as the one for my kids ride on Quad bike - I could ride on it and often both my kids and a neighbours child would all clamber on it and ride around the garden. A very good toy. However I'm pretty certain the motors on mine were 12V (2x17Ah 6v red batteries if I remember correctly - would run for about 1 1/2 hours in continuous use).

With a 35A fuse I'm guessing around 100 Watts per motor in original use. If you want them to last long enough to retrieve your boat run them off 6 volts and up gear the prop (and/or 3-4 blade big as you can get prop).  If you can get the motor to use 10 - 15A at 6V with gearing/prop sizing this will allow the motor to run in its sweet spot allowing most of the battery power to be used for propulsive force, as opposed to heating and knackering the motor.
picclock


This makes more sense. I'll see what I can do. The only reason I was going for 12 volts was that the diagram I' working off of is for 12 volts. I'll try her at 6 volts. I think the props will push the boat. Only time will tell. Thanks for hashing this out with me.

Bernd