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Thunder Tiger 40 Rebuild Project

earthsciteach

Moderator
Moderator
#1
I've decided to dedicate my RC efforts to the rebuild of the Thunder Tiger 40 that was generously donated to our middle school RC club by Pilot-294. The airplane is complete, with all parts and appurtenances included! The damage is pretty much isolated to the nose of the airplane, but she will get a thorough once over to be sure everything is flight worthy.

At this point, my questions are mainly materials and methods. Construction is standard wood and monokote stuff. The fuselage sides are balsa strips and sheets. The bulkheads are ply. What is the preferred glue to use? Would I be better off replacing the damaged sections (mostly on the bottom of the fuse) with ply from the rear landing gear forward?

I am REALLY excited about digging into this because it is a new area of RC flight for me! Here's a pic:
 

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Pilot-294

Senior Member
#2
Here's my 2 cents on it, do not worry about weight foreword of the cg because it's always been really tail heavy for me, try to keep it light behind it. With glue and such, I always used epoxy on the firewall, and either wood or CA on anything else besides maybe the wing spar or gear mount. Building up the front with ply may be a really good idea, as if it hits nice and hard, you may salvage it easier than balsa bits all over. Do try to glue the fuel tank even or above the carb and wrap the receiver and battery in foam to save vibration damage. All the servos should already have rubber mounts. That engine only has the idle needle and air less screw but NO low idle needle. If you get it ready before I or another pilot could help tune it up, this is basically what the manual said, I remember cus I lived by it trying to prep it every single wreck lol

Start by setting your linkage so that no trim is no throttle so you can cut the engine in an emergency or for convenience. Set your idle stop needle (stops the carb from closing all the way its the needle on top the carb) so that it closes but just barely. Then I ususally I turn the idle needle (long needle on the side) clock ways all the way in. This is as lean as it goes, then give it 2 or three turns out, richer, and attempt to start it. Cover the carb hole (without the glow plug starter) and spin it till the fuel line is full of fuel and no air. Then put the glow starter on and spin it up with the electric starter. If it won't start turn the needle out a little (remember to do this all with the idle at half trim and no throttle and priming the fuel lined is done at full throttle) once it starts Set the idle needle first by starting the motor, run it up to full throttle and find where the motor runs at peak rpm, you can tell by the engine noise, the louder the faster. DO NOT run the motor at this setting. Turn the needle out to make the fuel richer until you notice a slight drop in rpm. This is optimal running mixture.

Then the fun part (this took me hours to get right the first time or two it does get easier tho I promise!) set the air bleed screw (small screw at the front of the carb on the right side looking at the front) you want to be able to have the engine idle so it sits still on the ground, but idling really low is not necessary and if you dead stick it because of the idle it's no fun. Set the air bleed so that it idles as smoothe as possible. Then pick it up, at idle you should be able to pitch the nose 45 degrees up and down, your engine should remain smoothe the whole time. Tweak the air bleed, and If you run out of air bleed you may need to use the idle needle and then turn the air bleed back to where it was. And repeat the air bleed headache till it works.

Once it idles happy at 45degrees up and down you can fly. Fuel it up and go, I flew 5 minutes at 1/3 stick and used just under 1/4 tank. And then wrecked it landing hahaha :)

I do not know if that motor was ever broke in right looking back at it. I always took it for granted.

Try breaking it in before you fly even tho I did fly it.

To break it it simply secure the plane, start it, set it at full throttle and run it really rich, so it blows smoke from the exhaust. Run a full tank thru it at full throttle. Then do it again but this time every 2~ minutes return the stick to idle then full throttle 5-6 times. And repeat until you kill a tank of gas. It might tune easier for you that way and be an overall better experience!

If you want help I can walk you thru it whenever you want till I leave. Hope that all helped you out!!!
 

earthsciteach

Moderator
Moderator
#3
Thanks, Jesse. I'm hoping to get the nose back together this weekend. So, if things go according to plan, she should be ready to fly sometime next week.
 

Ak Flyer

Fly the wings off
Mentor
#12
I finished the wood work on my first balsa reconstruction. It's an interesting experience. I haven't had time to cover it yet buy my experience patching my cub gives me hope.

Went from this:
IMAG0853.jpg

To this:
2011-07-19_03-45-20_606 (1024x577).jpg


I think yours will turn out fine. Like he said, Good 5 minute epoxy for the firewall, CA for everything else. Nothing else is even worth bothering with.
 

pgerts

Old age member
Mentor
#15
A lot of good comments.
A agree of some but not all.
Making holes in the aft of the fuse like the last picture - yellow star on the fin - is a good start to get down the total weight.
If the plane is tail heavy then try to get a heavy spinner.
Tanks are normally not glued but packed in foam to prevent more bubbles than necessary in the fuel.
Ply is HEAVY - a good mix is the best. And making holes in the ply. If the plane is to strong in the nose it will break further back and the nose is normally easier to fix with some epoxy on the field.
 

earthsciteach

Moderator
Moderator
#17
Thanks for the advice, guys. Pgerts, great point! I'll stick with balsa for the fuselage as per the design of the airplane. Once I get it back together and determine the AUW and CG location, I'll know if I have to lighten the plane.
 

earthsciteach

Moderator
Moderator
#18
Progress as of 6:50 pm, EST: I've glued 3 bulkheads that were intact, but separated from the sides of the fuselage. I've also cut a new bulkhead from 1/8" birch ply and installed. I'm ready to cut out a new firewall for the motor mount. This will be 2 pieces of 1/8" birch ply laminated together. I really could use a scroll saw!
 

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