Motor Recommendation for a Balsa USA 1/4 Scale Cub

[Vulture]

Hold on before you tell me I'm posting in the wrong group. After you read the whole question, then you can tell me I'm posting to the wrong group. ;)

I have a Balsa USA 1/4 scale Cub sitting on the shelf. I would like to power it with an electric motor, and have enough power for AEROTOW. Well that's why I'm posting here. I was reading through the thread about an all electric aerotow. http://www.rcgroups.com/forums/showthread.php?t=710785 Which really sounds cool. And not wanting to hi-jack their thread thought I would start a new one.

So if those of you who have experience with electric aerotow have any recommendations I would like to know what they are. I was looking at an Astroflight Astro Cobalt 90 Motor with Super Box and 204D ESC. http://www.rcgroups.com/forums/showthread.php?t=705294 Is this too much, or maybe just right. :D Then there is also an Astro 60, Gearbox, Belt Drive, Speed Control http://www.rcgroups.com/forums/showthread.php?t=710315 which looks very interesting. Or would you recommend going brushless.

Thank you in advance for your recommendations.

Vulture

[GordonTarling]

These days, brushless is the way to go, for the better efficiency and lower weight, if no other reason. I'm just embarking on a 1/4 scale Piper Pawnee which will also be doing tow duty now and then. I reckon this model is going to come out around 20 pounds and will need around 4000 Watts in order to be able to tow a reasonable size glider. A power system like that can't be done on the cheap, but it can certainly be done at reasonable cost these days.

[jooNorway]

If I read the specs correct they say max 35A continuous on the Cobalt 90? Way too little IMHO... But of course you get tons of thrust with gear and that big propeller.
I would have concidered an Actro-motor for the project. Their web: http://www.actro.de/de/allg/index.html I don`t have anyone in the 60-size, only 40. But I think the 60-160 at 12S LiPo would be a great setup. Propably a 28x8 carbon-propeller suits...

A friend of mine converted his 1/4-scale Cub to electric. He used a Cyclon 160-motor on 10S. It was only partial success. Well, he towed my small 3,2 meter plane, but he didn`t have the right propeller! He used glowpropellers, and I know there is 20-40% more to get from a dedicated electro-propeller or a carbon. Later he put the Cyclon in the plane where it was meant to be (F3A) and converts to gas...

I hope you keep us informed on your choices and the results. Myself I starts to rebuild an old 1/4-scale Bellanca converting to gas :o It will be a Moki 45ccm with muffler inside the fuselage. The TUG-park grows, and we are a lot of people who will focus on 1/4-scale oldtimers for aerotowing. No glassfiber-originals allowed :p
Have Ka3, T-31, SG-38 and Moswey 3 in different stages of complete myself. Next year I think the sky will be covered with old beautiful gliders!

[cooper998]

Vulture,
I have seen a similar size plane the Sig Rascal 110 tow with a 5330 series AXI motor, most likely the 5330/18 and get a 4meter+ Ventus to a good release altitude. The BalsUSA Cub should be just as good or better with more wing area. I would stay away from the brushed motors unless of course you already have them and want to experiment. Old technology works and works well when everything is setup properly but is a bear when its not.

cooper998

[Vulture]

I have seen a similar size plane the Sig Rascal 110 tow with a 5330 series AXI motor, most likely the 5330/18 and get a 4meter+ Ventus to a good release altitude.
cooper998

Cooper I was just checking that out last night on Hobby Lobby's web site. I found they have an "Glow To Electric Conversions" page. http://www.hobby-lobby.com/glowtoelec.htm And they used a AXI 5330/24 in a Graupner Taxi 2400 with a 94 1/4" wing span. And they claim it's "suitable for large sailplane aerotow!"

They also show the AXI 5330/24 in a 12 foot wing span Telemaster. Now that should make a good aerotow plane I would think! :D

Vulture

[cooper998]

Vulture,
One of the planes we are currently using is a Taxi 2400 and it weights just over 24lbs ready to fly. It is built very strong. The 12 foot telemaster would probably be ok at 23lbs since the larger wing will give more lift.
When checking the HL web site you need to remember they are trying to sell you what they have not necessarily what you need. The 5330/24 while it draws half the amperage of the /18, it also provides half the thrust which is whats needed to get the plane and glider into the air. The /24 would need to go to ten cells to get close to the /18 motors thrust and rate of climb specs and its only rated for 8 cells. Remember you are not just flying one plane the added weight of a glider needs to be taken into account. From what I have seen most of the torque is needed getting both planes moving, once the glider is airborne its slippery shape and airfoil reduces the drag on the tow plane which translates to quicker ascent. These are just my observations, I am in no way an expert in aerotowing but I did stay at a Holiday Inn once.

Cooper998