Question FX3 vs XCub cowling and advice

[Neal]

I had wondered as well about VG's under the horizontal stab and if any CubCrafters owners tried it?

 

[Cactus Charlie]

NXCub, which definitely loses elevator authority unless you're carrying a little power.

At what CG position? With what allowed CG range?

 

[Cubonaut875]

I had wondered as well about VG's under the horizontal stab and if any CubCrafters owners tried it?

I know in the Supercub community there are two ways that are used to create more elevator authority: One are the Micro VG's that are exactly what we have, but are also on the underside of the stab far aft near the hinge line. The other is a strake just under the leading edge of the stabilizer. This system was used on the Top Cub by Cubcrafters. My Pa18 also had an issue getting into a full three point until I added the VG's and the gap seals. Good question for Pete at Cubcrafters - why no VG's on the stab. I think I asked that question but I think it was a nebulous answer.

 

[Cactus Charlie]

Most of my PA-18 time was in PA-18-180 restricted category glider tugs. They had a block of lead on the tail spring attach bolts. No issue with elevator authority and easy to land 3 point.

I suppose it's worth mentioning that 3 point landing a PA-18, or any other tail wheel aircraft, may require a very different pitch attitude depending on the tires fitted. I doubt Piper ever imagined the PA-18 would be flown on 35 inch tires.

I got a few hours in an early Husky of 8.50 tires. That airplane much preferred tail low wheel landings and seemed to be hard to 3 point. I was only borrowing it for a few weeks and didn't explore how handling changed with CG. I'm sure it would have been nicer with some weight in the back.

It's not just tailwheel aircraft that benefit from some aft ballast. I got a few hundred hours flying jumpers in a C-182. When the jumpmaster rode down after putting the students out he was always told to sit against the rear cabin wall for landing.

It's a lot easier, and probably safer, to move the CG than it is to try authorized aerodynamic mods.

 

[Neal]

I have a BRS which helps as well as a TacNet in the aft cargo with 15 lbs of stuff. The FX-3 is clearly nose heavy and I prefer the tail weight. I dare say the 65 lb limit in the aft cargo is underrated.

 

[Cactus Charlie]

I dare say the 65 lb limit in the aft cargo is underrated.

It's a 60 lb limit on my 2020 FX-3. Was it revised?

 

[Cubonaut875]

Agree with that also, that's why I keep 20 lbs of lead in the aft baggage when I'm solo. I would really like a compartment in the back tail where you could easily add a 5 lb lead bar to the tailwheel area whenever you wanted. Attached is a picture of Steve Johnson's (Supercub.org) PA 18 with the strake.

 

[Neal]

It's a 60 lb limit on my 2020 FX-3. Was it revised?

My memory does its own revising. It was what I could remember without looking it up. The point is it's lower than I'd expect.

 

[Neal]

I would really like a compartment in the back tail where you could easily add a 5 lb lead bar to the tailwheel area whenever you wanted

Next time at your plane remove the left aft inspection plate under the stab. You could put something in there I suppose. It's where the main bolt is for your tailwheel connection.

 

[Cactus Charlie]

The point is it's lower than I'd expect.

It's a rather vague limitation which I suspect is based on the cargo compartment skin thickness rather than any fuselage structural limitation.

I should be obvious that 60 lb of lead against the aft compartment rear wall is a very different loading than 60 lb of lead near the forward cross brace tubes, and that both are very different from 60 lb of something that fills the compartment.

I have been tempted to mark "stations" on the walls of the forward and aft compartments as is done in cargo transport aircraft. It's low down the list of things I'm never going to do.

How many FX-3 owners adjust pilot moment for seat position? I do. The AFM does not.