OldFart1

My Hellcat has sat for a few weeks (got a screaming deal on a used Hangar 9 100" Cub, been playing with it). Got the Hellcat down to charge the battery - looks like the horizontal stabilizer (both sides) have twisted (no longer parallel with the wings) along the "long" axis

Played with the heat gun a little - and right now it's sitting in the back of the truck under the tonneau cover (where it's nice and warm here in California) with a bit of "up" pressure on the low side.

Anyone else ever had this happen?

Hot Rod Todd

My Feedback: (1)

Be careful, there is some kind of optical illusion that makes them look twisted when they are not. I have noticed it on mine from the start, but it always flies fine.

OldFart1

I'll measure to be sure - but others have pointed it out. If I get a chance, I'll post a picture.

warks62

My Feedback: (140)

As Hot Rod Todd said be very carefull. It is exactly like he said it will look like it is warped when it is not. I did this on my maiden on the first one I built and ended up with a ton of up in it. Thing was climbing like a Banshee and had to fly it with down stick because trim was not enough. That is what you get when you don't use equipment even though you have it....LOL.

Shubova

My Feedback: (9)

Did you check the incidence and the CG after you maidened it? I'm curious if it was either one or both that caused the plane to climb.
Do you happen to know what the incidence is?
I haven’t started building mine yet but still collecting info.
Shubova
[8D]

warks62

My Feedback: (140)

I don't remember what the incidence is but I didn't have to change it and it flies fine like it is. CG is also fine where it is mine is balanced right on CG with no problem there either. The fault by me was I didn't check the deflection and just eyeballed it. The problem is that when you just eyeball it you need to look at the elevator more at the center of the elevator not at the end. Due to the shape of the elevator not the stab it looks like the elevator is warped down towards the outside. This is just an optical illusion due to the way it is shaped. Hard to describe, there is a compound curve on the end of the elevator that I think gives the illusion but when you put it together you will see what I mean. Nothing to worry about just don't be surprized if it looks like there is something there when it isn't. The plane flies great very stable!

OldFart1

Well, here's a few pictures - it's definately NOT an optical illusion (but I had hoped...)











So...ideas for a solution? I'm thinking heat gun and weighting the "high" side while restraining the fuselage

AirWizard

My Feedback: (3)

Is the stablizer tube level?

foodstick

Man, it did go bad sitting ! Maybe let it sit with the low side of the stab resting on a box and let it HOPEFULLY twist back? It seems like I read somewhere that there was a weakness in the kit in that area of the fuse. Its been so long since I read through this thread. You might need to possibly cut an access door somewhere so you can get in there and add some structure... I hope you can fix it without to much work


After thinking about it awhile It seems like there were some plywood plates just inside the fiberglass fuse where the stab butts up, If I remember correctly mine looked like the glue was poorly applied so I drilled some holes and added some expanding glue (elmers ultimate) My GUESS is that your plywood backers inside the fuse have delaminated from the glass skin, taking all the rigidity out of the area the stab glues up to...

Just a guess late at night on a two year old memory, so could be wrong

OldFart1

David - it was when I put it together

Foodstick - I'm going to try getting some light down to the end of the fuse on the inside - see if I notice anything. From the outside, it still feels rigid - nothing obviously loose (except my marbles maybe)

I'm going to try some heat and pressure - if that doesn't work, I'll cut into the bottom of the fuse and do a bit of exploratory surgery.

rcu_jonb

Have you flown it? I've scratch built planes that turned out like that and they flew fine (assuming I'm seeing just a horizontal stab isn't straight issue).

Course - I'm not the brightest bulb in the tree...

OldFart1

Plane has many flights on it - but that was before the stab moved.

AirWizard

My Feedback: (3)

I think your idea about using the heat gun is what I would try. Normally you don't need much heat to make the fiberglass soft.

warks62

My Feedback: (140)

I would go with the heat and then let cool down on the one low stab see if it will cure straight.

OldFart1

I'll try that tonight.

warks62

My Feedback: (140)

By the looks of the pics the vertical is straight so it has to be warped just where the stab goes through. I think I would try heating it up on both sides right where the stabs meet the fuse top and bottom. Then let it cool down with it is the straight position. You might even have to flex it over past straight then let cool to get the memory in the glass out.

OldFart1

This sounds like at least a two cigar project - I'll plan accordingly

foodstick

Have you had a chance to smoke those two cigars yet? or even work on the plane !! ha ha ha, I had hoped to see that you figured it out.

OldFart1

Smoked the cigars - but didn't get much chance to work on the Hellcat. Was actually going to try putting her up "as is" on Sunday - ran out of time. No build/flying this week - off to Washington DC on Thanksgiving, football on Sunday - then coming back on Tuesday so it will be at least next Thursday before I get a chance.

awatoto

Hi Guys Iv,e had my Hellcat 3 years or more now had hundreds of flights nothings ever gone wrong with it powered with an os160 is an awesome flying machine. That twisted tailplane can be remmedied by putting some black foam tape on the high side wing saddle to lower the wing and line it up with the stabilzer again did that on a sSeafury Iv'e got worked well for my thoughts
Mike down under in New Zealand

blue77

My Feedback: (178)

Hello, Just opened the box and looking at everything...very impressed so far. I am more interested in a winter project involving detailing etc....than flying. My wife is a pretty good artist so we are going to have fun with this........I would love to hear more info etc....WC

warks62

My Feedback: (140)

blue77, best info I can give you is start reading at the beginning of this thread. There is tons of info here which will answer just about every question.

OldFart1

Narrowly avoided disaster on Saturday....

In plugging both batteries in to charge Friday night (Receiver and onboard glow), I managed to knock her off the shelf onto her tail. Minor damage to one elevator half, easily repaired......

Fired her up on Saturday, boy I had forgotten how nice a YS 120 sounds. Gassers are nice - but nothing beats the sound of a large 4 stroke!

Flew around a bit to "reaquaint" myself with the plane, plus see if the horiz stab being out of plumb was going to cause any issues - no handling problems - but trim kept changing.....hmm, bring her in and check things out.

.....I must have managed to crack the spar in the horizontal stab when it fell off the shelf (about 3 feet) - it completely sheared on takeoff......

Oh well - now I KNOW I'll be cutting an access hole in the lower rear fuse. Fix the spar and cure the out of square horizontal stab all at the same time.

LDM

My Feedback: (15)

When Luke Zolner did his build on this plane he addressed the crooked tail area .
He ended up dremiling out that area , makeing it even on ecah side , building new supports ect .
Dont know if you can remove the tail with a dremil tool but it may be worth it

OldFart1

Probably do more damage getting the vertical stab sides off at this point - all 30 minute epoxy.

Will be cutting a hatch tonight in her belly near the tail - we'll see....