Need your opinions!

[James Powell]

I've basically finished the frame and body of my new skimmer using wooden yard sticks from Lowes and good ol trusty Dollar Tree foam board. The three pontoons are Flite Test floats designed for the Simple Cub (If it works, why redesign it?). Other than paint and water sealing, I'm ready for electronics. My question is; should I go with a single or double motor? Let me know what you think and maybe even the pros and cons of each set up?

 

[Sheriff]

Very elegant design.

I never built a skimmer but I suppose using 2 engines would allow you to steer using differential thrust.
But the single engine would be simpler and cheaper, and I think that is the whole point of the skimmer; simple and cheap.

au revoir
Guillaume

 

[mayan]

I have never build one as well but would think like @Sheriff that two motors and differential thrust would make stiring easier. I know FT has a video in which they built one, you should try looking for it, I am sure it might help you get some ideas .

 

[kilroy07]

Counter rotating props on two motors might help with torque rolls/ground looping as well.

 

[James Powell]

I have never build one as well but would think like @Sheriff that two motors and differential thrust would make stiring easier. I know FT has a video in which they built one, you should try looking for it, I am sure it might help you get some ideas .

I did see their video, it's what inspired this build. One thing I noticed is that they were using relatively small vehicles. This made me think that they were able to use one motor so well with a lighter weight vehicle. The one I'm building is significantly larger. This is the reason I was considering dual motors with differential thrust.

 

[FoamyDM]

I have/had an air boat build, and I didn't notice any torque rolling issues when we tooled it around the yard.

 

[James Powell]

I have/had an air boat build, and I didn't notice any torque rolling issues when we tooled it around the yard.

Have any pictures?

 

[FoamyDM]

I can get one tonight... it's a bit... busted. It met it's demise launching off a woodpile were it remained airborne for a few precious moment before landing on its top, to which the 10" blade chewed the cowling to small bits!

 

[Hai-Lee]

Just to be a little different, (mind you I have not built an airboat/skimmer for many decades), my biggest concern would be the weight of the battery and motor installation.

For buoyancy reasons I would have made the rear float much larger to house the battery and the electrics. Then I would mount the SINGLE motor on a pylon mounted on the front of the rear float to push the air over the fin/rudder for control. As a heavier rear float could cause the forward floats to bounce high and risk a rearwards somersault at speed I would angle the motor thrust down by around 5 degrees as a starting point. This should help lift the rear float and push/hold the nose floats down slightly on a high speed run!

Finally I would look to use a suitable 4 blade Quad-copter type propeller as it can provide significant thrust at low speeds where the resistance to acceleration is going to be greatest.

Just a few thoughts!

Have fun!

 

[James Powell]

Just to be a little different, (mind you I have not built an airboat/skimmer for many decades), my biggest concern would be the weight of the battery and motor installation.

For buoyancy reasons I would have made the rear float much larger to house the battery and the electrics. Then I would mount the SINGLE motor on a pylon mounted on the front of the rear float to push the air over the fin/rudder for control. As a heavier rear float could cause the forward floats to bounce high and risk a rearwards somersault at speed I would angle the motor thrust down by around 5 degrees as a starting point. This should help lift the rear float and push/hold the nose floats down slightly on a high speed run!

Finally I would look to use a suitable 4 blade Quad-copter type propeller as it can provide significant thrust at low speeds where the resistance to acceleration is going to be greatest.

Just a few thoughts!

Have fun!

My original thought to distribute the weight a little was to run two batteries for extended run time, and store one in each of the front floats. What are your thoughts on this type of weight distribution?

 

[Hai-Lee]

My original thought to distribute the weight a little was to run two batteries for extended run time, and store one in each of the front floats. What are your thoughts on this type of weight distribution?

It will definitely work but be careful that you do not bury the forward floats or the end will be spectacular. I lost one of my airboats when it turned submarine! The motor mount screws came lose and some fell out whilst doing a high speed run, (it was a gaser), The motor pointed skywards and the whole rear of the airboat lifted at the same time as the nose dipped below the waves. It disintegrated in a cloud of spray and the motor is still at the bottom of a lake some 1600Klm from where I currently live! I had fitted the Rx and batteries forward to try to keep the nose down which is exactly what I achieved.

The main issue you face is to keep the nose down and yet not bury it! Best suggestion I can offer is to make it as light as is possible even if it means reduced run times, (at least initially).

Have fun!

 

[James Powell]

It will definitely work but be careful that you do not bury the forward floats or the end will be spectacular. I lost one of my airboats when it turned submarine! The motor mount screws came lose and some fell out whilst doing a high speed run, (it was a gaser), The motor pointed skywards and the whole rear of the airboat lifted at the same time as the nose dipped below the waves. It disintegrated in a cloud of spray and the motor is still at the bottom of a lake some 1600Klm from where I currently live! I had fitted the Rx and batteries forward to try to keep the nose down which is exactly what I achieved.

The main issue you face is to keep the nose down and yet not bury it! Best suggestion I can offer is to make it as light as is possible even if it means reduced run times, (at least initially).

Have fun!

Hate to hear that happened to you, but that must have been a heck of a final showing! Any idea how fast you were able to get yours going?

 

[Hai-Lee]

Hate to hear that happened to you, but that must have been a heck of a final showing! Any idea how fast you were able to get yours going?

It wasn't measured as I was still playing with the setup but around 20 knots I suspect. The motor must have reached around 30 knots before it disappeared at the end of its ballistic flight curve! I got one thing from it - a very loud cheer from the spectator gallery!

Have fun!

 

[FoamyDM]

Here are the photos promised:
It was built with little to no planning the pop sticks were post failure reinforcement to keep it going.

 

[James Powell]

Here it is with a single motor set up.

 

[Sheriff]

Whoa, I was not expecting that; it looks very cool !! Just like the pod-racers in Star-Wars.

Well done sir!
Guillaume

 

[PsyBorg]

Needs fpv!