I have a Hanger 9 AT-6 with a Thunder Tiger .91FS. The CG is supposed to be 4 3/4" inches back from the leading edge. It needs 4.5 ozs at the TAIL to balance!.
Anyone else with this combo have similar results?
and, I assume that is means from the yellow part of the LD not the blue center section
Any help appreciated. Don't want to try and fly it with the butt hanging down

Just remember it is always better to be a little nose heavy -

Wow, that's a lot of weight. I'm very interested in this thread as I'm headed down the same path. I'm hopefully about the purchase my H9 AT-6 and will be installing an TT91FS on mine as well.

I'll send ya a PM with some questions if you don't mind.

thanks,

The CG is always measured against the fuselage. If you measure the CG from the yellow part of the wing the result is a plane which is tail heavy.

A nose heavy plane flies poorly, a tail heavy plane flies once.

I would start measuring the CG against the fuse. If it feels nose heavy it is easy to move the CG backwards. If it is tail heavy you are lucky to get it back in once piece.

--kaboomski;

I have the Hangar 9 AT-6 with a saito 100 in it. The balance point is up against the fuselage against the blue center section in front of the wheel wells. Mine balanced perfectly with the battery located back of the trailing edge of the wing. This is a great flying airplane in the air but very difficult on the ground due to the narrow gear and weak wires in the gear. You will scrape the wing tips on almost every take off and landing especially if there is any crosswind at all. I replaced the stock wire landing gear with the 3/16 robart wire that the make for the top-flite AT-6. What a difference that made. I don't have to worry about scraping the wing tips anymore. The airplane is very solid now on the ground. The wire gear from robart cost $12.00 and took only about and hour to replace.

Bumstead! I have the great planes balancer. I have the center section leading edge, the blue part where the wheels retract into up against the stand right against the fuselage sides. You then measure back 4 3/4 inches from that point. As far a changing the gear wires, just unscrew the four retract screws and remove the unit from the wing then drill a 3/16 inch hole in the existing retract unit. The hole that the unit comes with is about 5/32 inch. The existing wire that is in the retract will pull out after you loosen up the allen screw in the retract unit. The robart wire is the correct length, but the coil in the gear is different so you will have to use a dremel tool sanding disc to make a small cutout for coil on the gear to retract into the wing. No bid deal. Just takes a couple minutes to do it. It is well worth the time to make this adjustment. Good luck.

From where did you get the wire?

I purchased the 3/16 inch wire from Robart. You can go to their web site and look for the top-flite AT-6 gear. It will show the gear with the wire in it. They sell the wire for $12.00. Just drill the existing gear hole out to 3/16 inch and push the new wire in. Be sure to file a flat spot where the allen screw sets against the wire so it will not twist. As far as building tips go, I did everything according to the manuel except I left the wing strakes off. I just didn't like how they fit and they looked cheap. I used thirty minute epoxy to strengthen the inside firewall and that is about it. Take your time on the cowl. I spent quite a bit of time to get the dummy engine to fit right. I also installed a tru-turn AT-6 spinner. Good luck and happy flying!

Ok, great, thanks for the help. I'm looking at mine in the box now,,,she looks just lovely. [sm=sunsmiley.gif]

Hellcat,

I can't find them? Can you post the link please.

That tip about the CG against the fuse was the ticket.
Now I have to tear out the battery from the rear fuse and
all the other junk I stuffed in there trying to balance
the thing. H9's manual could have been a little more
explicit concerning where the CG is measured from.
Doing only constant chord wings everything was easy.
Wish I had asked first...Oh well..Thanks again everybody

The website is WWW.Robart.com. Select gear finder and go to the top-flite AT-6. The part # 618 but you only want the 3/16 wire which cost about $12.00

Bumstead,

So how did it balance with the TT91FS? Where did you move the battery to? Are you able to post pics? I should start building mine this evening probably.

Thanks,

I'll take some pix tonight and post. As I had moved the 5-cell pack to the rear section of the fuse to balance at the wrong place, I'll be moving that forward as well.
All this crap-ola would have never happened if H9 would have had a better description of the balance point.
I downloaded the manual for a Modeltech P-47 that I was considering as well and WHAT a DIFFERENCE. The P-47 manual was complete and very informative.
If the info is there "new-bee's" can really see whats-what and old-timer's can skip what they already know.
Mostly we talk about wood, build quality, flying querks etc. I can never get too much information, it helps. IMHO the quality "rating" of a model cannot overlook the quality of the manual.

Thanks, I plan to begin building mine this evening perhaps. Any other building tips? If you're able to post those pics that would be great.

thanks again,

The torque rod for the split elevator halves is probably the trickiest part to get right the first time. What I did was place them hinge line to hinge line and then use a piece of masking tape to hold them. Then use another piece on top where the torque rod enters.
Use a straight edge to draw a line on the masking tape above the entrance hole.
Slit the tape. Now you have a reference to drill the holes.
Also make sure the channel for the wire is parallel to the elevator halves.
Epoxy and tape the rod to the right elevator half before epoxying the stab.
This way you can make sure that the torque rod is parallel to the "driven" side of the split elevator
Once the epoxy has set, slide the torque rod through the fuse, epoxy the fuse/stab mating surfaces,insert the stab etc.

thanks,

How are you going to fuel your plane? Are you using some type of fuel dot or quick filler?

I installed a three line system with one fuel dot. Works great.

ok, great, thanks. That's what I had in mind.

Please be more specific where I measure the cg from. Is it directly against the fuselage, on the yellow or on the blue? First warbird I need some info. I have a 91 FX, I had to put 6 oz on the tail. And it very hard to land and it wants to stall easily. Probably because it is tailheavy.

Thanks ahead of time!!!!!!!!
Brian

The balance point is 4 3/4 inches from the leading edge of the blue fairing up tight against the fuselage

News from the flightline- Took the plunge and tried to fly it today.
1) wing generates huge amount of lift, so much so that it lifted off
after about 40 feet of roll-out.
2) Unprepared for such a quick jump, I tip stalled to the left (torque)
3) Totally pilot error..not inherant plane problem.
4) Here's the fun part.. The firewall separated from the fuselage clean...
like it was tack glued. I *****ed for a minute about hot-glue or something
but then I looked and had a plane that had survived a 10-15 foot tip stall to
asphalt, no fuselage damage other than a smashed up canopy
(it was cracked from the box anyhow) and a easily repaired firewall.
I have epoxyed the firewall back in place and will remount the engine
tomorrow,
When I began repairs I discovered that the firewall is
HOT-GLUED to the fuse. I'm no chemical engineer but is that stuff strong enough
to stand a .91 pulling it's guts out and flying stresses?
p.s. the TT.91RFS is a darn good engine, 9870 with a 14x6 Kseries MAS prop,
that's after less than a gal through it.
Whew
p.s. don't try and take off with the aeilerons in flaperon mode--bad things

Wow, thanks for posting. I'll be sure and try to beef up my firewall. Please keep us posted.

I gotta tell ya...what ever flaws the plane seems to have..that is a really good looking ARF. I have not had an ARF in a while but the T-6 sure does look good.

Everything went back togeather great. Glad that it broke away clean.
Re-epoxyed everything, mounted the engine.
One thing, for you out there thinking of using a TT .91RFS, the tank mount as-is
puts the tank way above the carb, read siphoning.
What I did was make a new base for the tank with some
ply planks, enlarged the hole in the firewall and lowered the tank about
an inch. Can't go too much or you will interfere with the wing top.
Cusioned everything with EPS foam.
I keep meaning to post some pix but still converting files.
New name for the AT-6...Battle Hardened!