'40' Sized Tugs / Tow Planes

[sneasle]

Hi All,

Long time lurker, signed up a little while back, before the site went down. Glad to see it back up, hopefully I can help contribute.

I've long been a fan of gliders, but in the past I've always been good friends with my Hi-start. Since moving here to Huntsville (waves at the few guys that I know are on the board here) I've learned that all the local clubs outlaw hi-starts in their bylaws, so I need a new way to get my birds in the air.

I recently picked up the PZ Ka8 (Like many others when it was on clearance) and have thoroughly enjoying putting time on it. This has made me look more toward putting tow releases in my other birds and along with outfitting one of my '40' sized planes as a Tug.

Now, I understand a '40' is considered small for a tug, but my largest plane (currently) is my 3M BoT. I'm 99% positive that a '40' should have enough mass to get it in the air.

That said, I need some help figuring out which bird(s) to do the 'upgrade' on. I currently have three options available to me, none of which are currently flying, some need more work than others.


H9 Arrow
Wing Span: 63"
Wing Area: 710sq"
Length: 52.5"
Weight: 5.7 lbs

GP Avistar (last gen)
Wing Span: 62.5"
Wing Area: 672sq"
Length: 55"
Weight: 6.5-7 lbs

Sig Rascal Forty
Wing Span:72.5"
Wing Area: 728sq"
Length: 51.75"
Weight: 5-5.5 lbs



I'm leaning toward the Arrow or the Rascal. I may actually do both...

My thought is to go with something like a Tacon60 or MonsterPower60 (400kv) spinning a 15x8 on 6S. eCalc tells me that this gives me something like 50A @ WoT @ ~1000W. Should be plenty, right?

Thoughts? Am I in the ballpark, or should I rethink this entirely? Obviously I have no idea exactly how much power is needed aside from 'more'...

[JimD]

First...are you committed to electric or would you consider a glow engine? Electric power in this size range works very well but has limited flight time. 2-stroke glow is the least desirable, but 4- stroke glow works very well and has a much longer flight time than electric.

I am very familiar with the Avistar (semi-symmetrical wing), nice flying airplane, but may be a little too fast.

Are either of the other two, Rascal or Arrow, flat-bottom wings?

Although any of them can be made to work, deciding which would work the best is a good idea.

[sneasle]

Hi Jim, I appreciate the response.

No, I'm not committed to going electric on this, I just don't have a lot of glow equipment. I've got a .91FS sitting in a bag somewhere, but it needs some repair work (cracked case) before it could go back into an airframe. I actually already have a MonsterPower60 laying around. What I originally bought it for, I have no idea. Might have been the Rascal actually.

Yes, the Avistar is fast as a trainer. It was my 'first' plane. It served me well. The Arrow is also a semi-symmetrical wing, but it is a bit flatter than the Avistar's. It was definitely a slower plane.The Rascal has a relatively flat wing. It's possible it has some curve to it, but if it does it is minimal. The wing on the Rascal is elliptical though. Not sure if that has any bearing on this discussion.

[JimD]

The Rascal 110 has been used as a tow plane with great success, so I think my vote is for the Rascal. The power system should give about a dozen Easy Glider tows between charges, not bad as this translates to about 25 minutes of flight time. Coasting back to land and waiting for the next plane to hook up does not consume power.

[sneasle]

Yup, I'm kind of leaning in that direction. That said, even if I only get 5 tows up on a charge, that should be enough for me. My main reason for wanting to build this is for those days when I'm the only glider guy that shows up to the field. It would be nice to have some way to get them up, otherwise I'm stuck staring at them while they sit in the grass.

I figure if I can talk someone into flying the plane back to the ground for me 5 times in a day, it was a good day.

[sneasle]

I would also be interested in an landing gear recommendations you guys might have. I figure I'm going to need to get something a bit taller...

[JimD]

This one should work well:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXNM65&P=0

[sneasle]

Thanks Jim, I will take a look.

[Alexis Scott]

I have towed a few light weight 1/4 scale models with a low wing sportster of the size your talking about, you don't need massive power but a low powered tug requires a little more communication between both pilots to make it a simple process, Ive towed my fathers Ka8 with his 50 four stroke powered hangar 9 Cub and thats a super simple blast of fun to do. As for the question between electric and glo, thats a tough one for me as Id assume you wont be towing lots of gliders and having a quiet and simple electric tug certainly has appeal.

[sneasle]

Thanks Alexis,

Ya, clean and quiet is why I am leaning more toward electric. That said, if I run this off of 6S, I can build a 'flight pack' from 3s2200mah batteries, of which I have plenty.....

[sneasle]

Any thoughts on a good Tug side tow release? I'm torn between making something and buying something.

[JimD]

Take a look at this article:

http://www.rcaerotowing.com/1540-fabricating-a-simple-and-inexpensive-tow-plane-release-mechanism.html

[JimD]

Here is how we did the inside servo hookup:

[sneasle]

Thanks Jim, much appreciated. Looks easy enough to install, might have to ask someone nicely to bend one up for me though.