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1st R/C Airboat build

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Old 11-11-2013, 02:23 PM
  #51
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Quote:
Originally Posted by St.Marek View Post
Hello.
Thanks for informations about GPS. AirBoat on water is jumping too much. You must to change the center of gravity and will be ok. Can you drift on this boat ???


Greetings from Poland
Marek&Wojtek
The way my hydrofoils balance the bow ends up being lighter for speed. Hold by the prop nut. If it hangs level, it should be good to go. If its bow heavy, it's gonna hop (porpoise). It will probably porpoise if its too light in the bow and consequently blow over. This boat has always been bow heavy and it's almost always porpoised. With the right amount of weight in the right spot it will balance out. I started this R120 install with the prop's centerline (thrust line/balance point/CoG) at 1/3 total hull length +1/2". Something like 10 3/4" from the transom on a 32" length hull. The Lowrance GPS adds 8oz of weight to the boat with Alkaline batteries (2). There are MUCH lighter options like the little Garmins. So to recap - bow heavy = move engine forward. Bow light = move engine back.
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Old 12-14-2013, 10:01 PM
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A airboat with a rudder in the water is not what a airboat is about. A airboat is designed to go over weeds and wet grass and even on the bank if your engine is powerful enough, its not ment to have a rudder in the water its supose to have air rudders.If you want a rudder in the water build a v bottem or something and you can go realy fast and turn realy sharp. If you want better control put 2 slats on the bottom of the hull about 6 inches long on each side and make the rudders the same higth as the prop to get full forse of the air over them. I have 4 air boats electric and nitro and they run fine and turn good ,better in the direction that the prop is turning but ok the outher direction too.I have a 51 inch airboat with a 140 nitro turning a 18 inch pusher 3 blade prop and it goes where ever it wants to go and runns in the 40 mph...Bob
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Old 12-15-2013, 07:39 AM
  #53
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You mean glow engines, correct? I am in favor of the air rudders as well.
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Old 12-23-2013, 08:59 AM
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I don't mean to be rude, but if your boats went as fast as mine do, you'd need a wet rudder too. They steer like they're on rails most of the time much like a car. Try running 50mph with an air rudder and see what happens. Once you get over 25mph, they're just too hard to control. Sorry. There isn't a soul on this Earth that will convince me to dump the wet rudder in favor of an air rudder on water. Not gonna happen. If crispyspa catches this, I hope he will chime in. He has more experience than any of us, but I'm sure he will agree with me. For speed, wet rudder is the way to go. If you want to be able to slide, drift, spinout, or whatever... Then the air rudder is the go-to. I don't care for the sliding and wide turns. I like having tight control of the steering. I just do. Aside from preference, the hull sides have such a shallow angle, it's much easier to catch a wake and have a lot of water come over the side. Getting a bunch of water in the prop arc usually kills the engine.


So do you guys have some pictures of your GPS readings of your boats with air rudders?

Last edited by 1QwkSport2.5r; 12-23-2013 at 09:13 AM.
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Old 12-23-2013, 02:14 PM
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A real airboat is air rudder controlled, not controlled with a water rudder and are not speed boats. It is arrogant of you to say one person knows more than another, not trying to be rude. The speed you speak of 50mph, yes I would recommend a water rudder.
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Old 12-23-2013, 03:06 PM
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Quote:
Originally Posted by rcairboater View Post
A real airboat is air rudder controlled, not controlled with a water rudder and are not speed boats. It is arrogant of you to say one person knows more than another, not trying to be rude. The speed you speak of 50mph, yes I would recommend a water rudder.
How is it arrogant to say one guy knows more than another? I've seen over half a dozen boats he has built, I've not seen any you've built. I can only assume some other builders know more than say you do since you say an airboat must be slow and air-rudder controlled. That's your deal, its not mine.

If I was building for the "scale" look or wanted to be the most "realistic" then I'd build differently. But I am not a scale of realistic builder. My boats are built to look good, be fast, and be fun. I think its ignorant of you to come into my thread and tell me I cannot have a wet rudder on MY boat built by ME to MY liking. A toy airboat is not a "real" airboat anyway and I don't care.

One more thing; prop cages are for wusses.

Last edited by 1QwkSport2.5r; 12-23-2013 at 04:36 PM.
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Old 12-23-2013, 05:05 PM
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Your opinion, and safety is obvious not your concern.
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Old 12-23-2013, 06:52 PM
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Quote:
Originally Posted by rcairboater View Post
Your opinion, and safety is obvious not your concern.
Perhaps instead of being an ignorant jerk, you should think about the fact that some of us want to build airboats for speed. Speed and air rudders don't mix. You can't use electric starters with cages and they create too much drag. The slats on the keel like the other guy mentioned adds unnecessary drag to an already draggy design. Why make it slower? Man that sounds stupid.

So you can take your advice elsewhere. It serves no practical purpose in my threads.

Last edited by 1QwkSport2.5r; 12-23-2013 at 06:54 PM.
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Old 12-24-2013, 06:36 AM
  #59
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Quote:
Originally Posted by fisher3208 View Post
A airboat with a rudder in the water is not what a airboat is about. A airboat is designed to go over weeds and wet grass and even on the bank if your engine is powerful enough, its not ment to have a rudder in the water its supose to have air rudders.If you want a rudder in the water build a v bottem or something and you can go realy fast and turn realy sharp. If you want better control put 2 slats on the bottom of the hull about 6 inches long on each side and make the rudders the same higth as the prop to get full forse of the air over them. I have 4 air boats electric and nitro and they run fine and turn good ,better in the direction that the prop is turning but ok the outher direction too.I have a 51 inch airboat with a 140 nitro turning a 18 inch pusher 3 blade prop and it goes where ever it wants to go and runns in the 40 mph...Bob
fisher3208 Here in the real world we know what an airboat is supposed to do and be. It's important to keep safety in mind as well. These glow engines with a prop turning at rpm can cut like a razor.
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Old 12-24-2013, 06:59 AM
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In the real world people have choices. I don't appreciate your attitude telling me I can't use this or I have to do that. That's BS. I highly suggest you come back to reality. Now please, start your own thread to preach your beliefs there instead of jacking my thread.

Common Sense Warning: spinning props will cut you. DUH. If you stick your hands in the prop arc, you will get hurt. DUH. Paint the tips of your props with bright colored paint to make it easier to see.

Last edited by 1QwkSport2.5r; 12-24-2013 at 07:04 AM. Reason: Added common sense warning.
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Old 12-24-2013, 11:53 AM
  #61
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want to build an air boat ,could I get former drawning of hull from you is that possible? very nice boat ,currently building a polish tug,but have the stuff to build an airboat,
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Old 12-24-2013, 01:38 PM
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Enjoy your air drive boats. Oh, and I would advise you stop telling people prop cages are for what you call wusses. ( From your limited vocabulary) It's poor advice.

Adios
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Old 12-25-2013, 08:29 PM
  #63
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Quote:
Originally Posted by rcairboater View Post
Enjoy your air drive boats. Oh, and I would advise you stop telling people prop cages are for what you call wusses. ( From your limited vocabulary) It's poor advice.

Adios
My vocabulary isn't limited. I said that just for you. I don't use prop cages, but that doesn't mean anyone else shouldn't. If you can't figure out how to not stick your fingers or hands into the prop or you run your engine with people too close, that is not my problem. I am cautious with my models, as should you and anyone else. This is common sense people. Prop powered models be it an airplane or boat are dangerous. Read the warnings in your engines owners manual.

Now that we have wasted these last posts dealing with something that should come as common sense, let's move on.
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Old 12-25-2013, 08:31 PM
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Quote:
Originally Posted by wavegrave3 View Post
want to build an air boat ,could I get former drawning of hull from you is that possible? very nice boat ,currently building a polish tug,but have the stuff to build an airboat,
The plans I used were made by the original designer of this boat. I had to fill in the blanks. Here is a link to the page I got the plans from. Hopefully all of the links still work as it's been a few years since I used them.

http://www.rcairboats.net/phpBB/view...php?f=15&t=168
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Old 07-16-2016, 11:44 AM
  #65
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It's been awhile since this baby has been run, so I felt like a good day to go out and run some fuel through it. The carb was a little sticky, but once freed up, she ran like she always does. This boat is a real failsafe.. Almost always runs great. https://youtu.be/6KGEXRVP5js
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Old 07-17-2016, 11:49 PM
  #66
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looks really good flying around the pitch what is she like on the wet stuff
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Old 07-18-2016, 04:04 PM
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Quote:
Originally Posted by Paulekins View Post
looks really good flying around the pitch what is she like on the wet stuff
It's pretty fast with the big 20cc 4-stroke on it - so much power it's been hard to get it to balance perfect and not porpoise at speed. It runs dead flat with a 10-15cc 2-stroke though. I use a wet rudder on it on water, so it turns and drives like its on rails. I think I have a video of it running on water with this engine... I'll post a link if I still have the video online.
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Old 07-18-2016, 11:18 PM
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thats a heck of an engine you will be breaking the land and water speed record with that look out the Campbells
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Old 07-19-2016, 03:03 AM
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It will flip over by 45mph with this engine. I'd need to go back to a 2-stroke on a smaller prop to lower the CG and get more rpm. But really - this is not a speed machine. It's fun the way it is. I wanted to tune up the 4-stroke so I can clean it up and oil it. I have some other engines I want to try on it. I might even go crazy and stick my Jett .56LX on it for an experiment. We've already swapped the Jett onto another boat previously... May as well keep moving the $495 slug around.

Jett 56lx hull swap

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Old 07-19-2016, 06:21 AM
  #70
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Here's a decent video of this boat with an Enya .60 four stroke engine on it with wet rudder and I think 12x6 prop. I've never been able to get it to not hop in the turns. The porpoising can be cured if I had spent the time to balance the boat (move the engine forward) better. https://youtu.be/fVadTr40eQw

Heres a short video on the water with the 1.20 four stroke engine: https://youtu.be/dUUC1GWJfgQ
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