Tail Heavy ARF's
 

This is the 2nd tail heavy plane after follwing the user manual. Have a Tiger 2 low wing by Goldberg. It comes with trike gear where the two main wheels are mounted directly at the CG on the wing and a nose wheel. I'm using a OS .46 AX engine that is mounted beyond the 4 1/8 inches as suggested by the manual. Matter of fact, the engine is mounted as far forward as you can get on the mount. You have a roughly 1 inch CG range. After I get all the stuff in there including a 4.8 volt 1600 nimh rx pack up against the fuel tank, the plane balances in the suggested range. However,
the plane will not sit even. When you put it on the ground, it falls toward the tail thus the front wheel isn't contacting the ground. If I put in 5 and a half ounces of weight under the engine, the front wheel will touch. I'm wonderin if the designer and testers were drinkin Ripple when they were testing!!!! [:@] What I have for weight is a metal plate and a big washer.
I'm thinkin of just epoxing the damn things to the wood protrusion that is attached to the firewall and juts out. Of course, they will vibrate loose, hit the prop, break prop while I'm on final approach and that will be the 3rd crash in the cornfield.
My Hangar 9 Twist was the same way. Had to add 6 ounces to it before it would balance right.

Dave...

RE: Tail Heavy ARF's
 

If the landing gear is at or about the CG then that lends itself to being a taildragger. In a trike configuration you would want it slightly behing the CG in order to keep the nose on the ground. Try contacting Goldberg and see what they say about it before you add balast.

RE: Tail Heavy ARF's
 

The answer to your question is that the placement of the main landing gear is in the wrong location. All trike landing gear aircraft
must have there main gear located aft of the CG. You problem is a direct result of having the main landing gear mounted directly on the CG.
My assumption is based upon the aircraf having a constant chord wing with the CG set at 27%.

RE: Tail Heavy ARF's
 

Either the ARF kit was faulty, or you failed to locate the main gear correctly. I have seen lots of Tiger 2's & not a single one exihibited that problem.

RE: Tail Heavy ARF's
 

Don't be offended but, is it possible that you are measuring the C-of-G location incorrectly?

RE: Tail Heavy ARF's
 

Guys, where the main gear gets located, there are two holes you can see thru the ultracote along with the gear channel. I will eventually make a taildragger out of it probably next year. I did measure CG correctly. The center of the 1 inch range falls directly where the
channel for the main gear is located. I shoulda checked all this at home. I found out at the field because I wanted to maiden it this afternoon. Its a nice plane but I changed out some of the hardware such as nuts and lockwashers on the motor mount and front wheel gear. Blind nuts that are supposed to seat themselves never do. I also use nylon lined nuts on the motor to the mount.

Dave...

RE: Tail Heavy ARF's
 

You could just bend the gear back a little, or maybe swap them from one side to the other. Maybe thay are bent differntly.

RE: Tail Heavy ARF's
 

Thanx for the tip Terry! I was thinking that. If I can bend them about 1 inch back. Then I may not have to use any weights up front.
I know with the Arrow I used to have (crashed on friday), the guy who instructed me had me bend the main gear forward a tad. What he checked was moving the tail downward to see how much it would spring back up.
You guys mentioned trike gear, the main gear is always behind the CG. And then if a taildragger, the main gear is forward of CG?

Dave...

RE: Tail Heavy ARF's
 

It is true that some ARFs turn out tail heavy. I think this is due to some of them getting heavier balsa in the tail as opposed to the prototypes.

It is also true that some modelers tend to use too much glue on the tail or change out some of the components for stronger, heavier ones.

No matter which one is correct, you have a tail heavy model that needs fixing.
-First, move the battery as far forward as you can get it. In the tank compartment under or beside the tank is best.
-Second, try a brass heavy hub on your AX.
-Third, use a plastic prop instead of a wood one. they weigh more.
-Fourth, check for anything you may have added extra to the tail and remove it.
-Fifth, if you have heavy pushrods, you might want to change to pull-pull cables on your rudder.
-Finally, add some weight to the nose.

RE: Tail Heavy ARF's
 

The main gear on the Tiger ARF is bent so that the axle is either 1" (approx.) ahead of the mounting slot or 1" behind it depending on which strut you put in which side. Switch the main gear struts side for side and see if that helps.

Jim

RE: Tail Heavy ARF's
 

I don't think you are right Ed. He said it balances on the CG just won't sit on all three wheels. I think it is a placement of the gear problem.

Dave, you are right. On a tail dragger you want the CG to be aft of the gear and on a trike you want it in front of the CG. This will make sure the plane sits on the gear when you want it to. If you put the gear aft of CG on a tail dragger the plane will nose over on take off rolls. If you put the gear forward of CG on a trike it will do what you have now, tail will drop when it sits on the ground.

If you know someone with this plane compare the distance from LE to the gear.

MHO

RE: Tail Heavy ARF's
 

I think I got it now. I took out the main gear. The rods are straight. I put them in a vise and bent them. The plane now will
sit on all 3 wheels. Apparently, maybe someone, a Quality Control guy was sleeping when this plane was designed.

Dave...

RE: Tail Heavy ARF's
 

LuckyArmpit, You've got to get rid of that cornfield. Its inherently evil. Do an exorcism on it, get the help of some Druids, whatever it takes [ short of threatning the farmer] One walk through a wet cornfield is all it takes to convince me not to fly over them. We both know they are sharp. Seeya, MM:D

RE: Tail Heavy ARF's
 

everyone is correct. Bend the main gear slightly back and everything will work out. There was number of threads on here that talked about this. I do highly suggest to convert it to tail dragger. You will never go back to a trike again once you do the change.

RE: Tail Heavy ARF's
 

Okay, I've attached a pic. It sits okay now. BTW, the co-pilot's name there is Brutus. He don't fly too good but will tell you where the plane has landed. He aint chewed one yet!!! (my electric foamies of course)
Thanx to everyone for the suggestions!!! Yep, walkin thru cornfield aint no fun!!!!! Lotsa mud on shoes. The Tiger is gonna wind up a taildragger before too long. I already have a Twist and its a taildragger....

Dave...