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Steering issues with air boat

Old 02-27-2021, 08:32 AM
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ANDRIS GOLTS
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Default Steering issues with air boat

Hi all .I was testing my new airboat in the snow yesterday the hull is 21 inches in length with a 8 inch beam power by a 35mm outrunner 1400 kv outrunner on 4s lipo the steering servo is a Traxxas 2080 set up as a push pull system with the servo set up 1 3/4 inches in front of the air rudder with as servo saver mounted on each steering rod i got about 1 hr of run time before the nylon servo gears stripped . What makes this more complicated im not allowed to post pictures till i have at least 10 posts on this site ! Could anyone suggest what might be the issue here without seeing any pictures ! Regards Andris Golts.
Old 02-27-2021, 10:10 AM
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Originally Posted by ANDRIS GOLTS View Post
Hi all .I was testing my new airboat in the snow yesterday the hull is 21 inches in length with a 8 inch beam power by a 35mm outrunner 1400 kv outrunner on 4s lipo the steering servo is a Traxxas 2080 set up as a push pull system with the servo set up 1 3/4 inches in front of the air rudder with as servo saver mounted on each steering rod i got about 1 hr of run time before the nylon servo gears stripped . What makes this more complicated im not allowed to post pictures till i have at least 10 posts on this site ! Could anyone suggest what might be the issue here without seeing any pictures ! Regards Andris Golts.
First of all, go to the main forum page and scroll all the way to the last section called, "RC Universe Support". In it you will find a TEST section. Post five quick test posts in there and you're good to go for pics.

Now about the boat. Is it a ready to go type of model? Complete with radio? Or did you build it from a kit or scratch?
How big is the air rudder and where does the hinge line go on it? IOW is it hinged at the leading edge of the rudder or is there a pivot at some point behind the leading edge? And just where does the air rudder sit in relation to the prop disk? i.e. is it dead behind the center of the prop or is it offset to one side or the other? And if so, which side? And when viewed from behind, what direction does the prop spin? Clockwise or counter clockwise?

About the servo, make and model please? What is the torque rating for it and what voltage are you handing to it? For that matter, what radio are you using?

Your nylon gear train is the weak link in all this. To start you need a servo with something more robust than nylon. You might possibly need a servo that produces more torque as well. I suspect too your rudder needs to be hinged differently. You don't need a verticle fin to hinge the rudder to like you'd find on an airplane. What you need is for the rudder to pivot (hinge) at a point so that 30% of the rudder is in front of the pivot. What that does is 30% of the rudder while still turning the boat will also be helping the servo vice fighting it. That takes a tremendous load off the servo. Support the rudder at the pivot point on both the top and bottom of the rudder. Ideally a twin rudder set up would be better.
Old 02-27-2021, 11:27 AM
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Got RPM
 
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The OP identified the servo in the original post, a Traxxas 2080 micro servo. I’ve not had good luck with Traxxas servos but some like them. The OP’s kit boat is a tiny, well-known proven model, no need to reinvent the wheel with different rudders, etc. The cause could be his use of a push/pull linkage, binding is common in those. The recommended linkage was a single push rod. KISS.

He should consider upgrading to a metal-geared servo, a mini if he has the room.

Last edited by Got RPM; 02-27-2021 at 11:56 AM.
Old 02-28-2021, 11:07 AM
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ANDRIS GOLTS
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Thanks to both of you for your input the boat i used is same dimensions as the the Stevens aero but a scratch build with some design changes including non -trip chines a prop guard and a larger radio box and option of mounting a 22mm or 35mm outrunner motors on the motor tower when my computer i.t. stops by i will have her try to re-post the pics again i ordered a set of metal gears for the Traxxas 2080 but will have to wait a couple of weeks for them to arrive by then the snow may be gone i will dismantle the boat for painting and will have to test on water grass and weeds. Thanks again . Regards Andris Golts.
Old 02-28-2021, 06:06 PM
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I'm thinking it's too small of servo as well. I just looked it up and the 2080 is a 41.7in/oz servo when using 6volts. Looking at the picture Got RPM posted, I can see why the servo failed in a push/pull set up. I have to agree, keeping it simple would be a benefit in this case, as would a more powerful servo with metal gears
Old 03-01-2021, 05:03 AM
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Originally Posted by Hydro Junkie View Post
I'm thinking it's too small of servo as well. I just looked it up and the 2080 is a 41.7in/oz servo when using 6volts. Looking at the picture Got RPM posted, I can see why the servo failed in a push/pull set up. I have to agree, keeping it simple would be a benefit in this case, as would a more powerful servo with metal gears
I agree on the servo. Physically too small. People forget that while cute, these little servos may produce the torque one needs but by being so small critical components like the gear train are also small / thin. This reduces the stress they can handle as well. Often failing under the torque the motor can produce. Some of these gears are what? 1/32 inch thick? And what kind of plastic? Not a formula for gear train survival if you ask me.

If it were me I'd make changes to the radio box to allow a physically bigger servo. A standard size at the same torque should do fine. The power / torque is there. Now he needs the physical characteristics to support it.
Old 03-01-2021, 05:10 AM
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Originally Posted by ANDRIS GOLTS View Post
Thanks to both of you for your input the boat i used is same dimensions as the the Stevens aero but a scratch build with some design changes including non -trip chines a prop guard and a larger radio box and option of mounting a 22mm or 35mm outrunner motors on the motor tower when my computer i.t. stops by i will have her try to re-post the pics again i ordered a set of metal gears for the Traxxas 2080 but will have to wait a couple of weeks for them to arrive by then the snow may be gone i will dismantle the boat for painting and will have to test on water grass and weeds. Thanks again . Regards Andris Golts.
Your IT can't help you with pictures until you have 10 posts. Again, just go here: Test Posts And make 4 test posts to reach your 10 required for posting of pictures.

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