Topflite P39
 

Has anybody out there built a T.F.P39 with retracts using the Robarts nose gear? Seems like a lot of bucks an I am not sure how they will hold up on a grass field.What about just using a 90 degree nose gear?
Thanks
Cope

Re: Topflite P39
 

I have this kit, too. I had read the reviews from Top Flite's website...

http://www.top-flite.com/reviews/index.html

...and one of them mentioned the nose gear ripping out and having to reinforce the mount. It's a long strut with a small wheel, so there is a lot of leverage, and it can be a problem if not very solidly mounted. I would think that an oleo strut like the pricey Robart unit would hold up better than a springy wire strut on grass, though.

My solution? I fly off grass too, so I plan to make it a taildragger. The XFL-1 Airabonita was designed for carrier operation. Only 1 prototype was made, the colour scheme was aluminum with chrome yellow wings - good visibility. I'll be on my own to figure out the landing gear installation, however...

JW

Re: Topflite P39
 

I am a little confused when you say "90 degree nose gear". Are you talking about a 90 degree rotating nose gear or a firewall mounted nose gear?

If you mean "firewall mounted nose gear" I would HIGHLY recommend it, IMHO.

As mentioned in the in your post and the post above, nose gear strength is what you are looking for. The firewall mounted nose gear would be considerably stronger since you can really beef up the firewall (thickness) to accommodate the nose gear. It will be a simpler install as well (again, JMO)

As long as you are using a metal nose gear retract mechanism, you should have no problem with strength.

Re: Topflite P39
 

I had this plane and the problem is the length. If you do not get it long enough you wind up with a negative angle of attack. And no matter what you do it will not rotate. Beef up the rails extend them past the fire wall into the engine area. That way you can move the retract farther forward and get a longer strut in there. A fire wall mount will not work, you will NOT have the length you need. Been there done that and if I only knew before the initial build it would have been much, much easier.

Re: Topflite P39
 

I agree 100% with the incidence issue. You MUST have the plane sitting with a slight nose up attitude or it will not take off. But incidence is a function of NOSE GEAR length and MAIN GEAR length.

Just my 2C, but it would be prudent to make the main gear as short as possible (and yet still retain scale appearance). which would allow you to use a shorter nose gear and yet still have the nose sit with a positive angle to make take-offs easier. At least that is what I would do. Then you can still have the option of doing a firewall mount or a rail mount nose gear. Not having owned a P-39, Canadian Ice might be right tho, there might not be enough room behind the firewall/wing to fit an adequate strut if you went with a firewall mount. The only way to know for sure it to have it in front of you and see what length you need to make the nose-gear after you make the main gear as short as you can and still have it look good. JMO

Re: Topflite P39
 

Thanks for the response guys.J.W. the Airabonita is a good subject to do.I read something about that in one of my old Scale R/C Modeller magazines(1976).Max,when I mentioned 90 degrees for the nose gear I meant the strut is not raked foward like the full size.Anyway I have solved my problem for now.I have decided to build the P-40 and put the Airacobra on the to do list for now.
Cheers
Bob