The used trainer I bought is waaay tail-heavy.

Because of the space needed, and it's location, I would have to add a pound of lead to the thing to balance it. The previous owner had a bunch of steel bars zip-tied to the thing. I have ordered one of those heavy prop nuts, like 2.5 oz. I know it's just simple physics, but is this a better solution than adding lead to the already cramped firewall?


I thought of adding lead to the inside of the spinner.....and then quickly remembered the basic F=M*A and abandoned the idea entirely. That would be like using scotch tape to hold a quarter to the edge of a circular saw blade.

By the looks of things, I will need both the heavy prop nut and some lead on the firewall.

This is a right flyer MKII 40 T. Why is is so darned tail-heavy???

Any Ideas?

I am not sure why it is so tail heavy, but one thing you could do is to extend the firewall. That would move the motor front and since its the heaviest part on the plane, you would not neet to move it too much

Assuming you have moved all that can be as far forward as possible.
In my very limited experience, increasing the wing loading by adding that much lead to a trainer would not be good.
How old is it, what I mean is, it may be worth remaking the verticle and horizontal stabelizer, using lighter materials and techniques.
Check control rods and linkages, if they are heavy, change them.
Whats the landing gear, Trike, or taildragger. If it is Trike, You can get a heavy nose wheel.
If it is Taildragger, you could convert it to trike. Change the engine mount for one that accepts a nose wheel. The nose gear will help with the balance. When you do this, you could even get a longer engine mount and move the engine as far forward as you can

Just a few ideas, hope it helps.

Dave.

I'd move the engine forward. A piece of 1/4" ply laminated to the firewall, then a long mount.

Good luck,
Dennis-

And maybe go with a 4 stroke engine?

I hesitate to suggest this -- but -- can you shift the wings aft by a bit?

Has there been repairs made in the tail area with maybe too much epoxy or other material used?

I'm with bruce. That long tail moment can make seemingly modest weight additions (plywood and epoxy for example) really work against you.

Mark

Heavy nuts on the crank can affect the responsiveness of the motor. The best way is to move existing mass around. If you already have your battery pack as far forward as possible, consider moving you motor forward. Usin a longer mount or making up a ply "donut" ring to move the existing mount forward might do the trick. I know it will look a bit strange, but less weight is always better. Low wing load = longer glides.

Safe Flying!

The one I have was not. If a recall the balance point is 3 1/2 from the leading edge. Are you sure everything is in the correct location??

Can you post pictures of the radio and engine installations?

agexpert,

I have exactly the same ARF trainer that you are dealing with. I only bought it because I had just crashed my kit built Goldberg Eagle II and wanted to get back flying quickly. (also because it was on the hobby store wall and was CHEAP lol). I have an OS 40LA in mine and I had to use pretty much exaclty a pound of weight, some of that was a weight on the end of the prop shaft and the rest was the stick on weights attached to the cheeks of the fuselage as far forward as I could get it.

Hi!
Never ever add lead to a an airplane if at all possible!
Why? Because heavy airplanes fly so bad compared to light ones.
Show us some pictures of your airplane please!
I would move the servos and battery forward as much as possible before I added any lead.

Regards!
Jan K
Sweden

Many trainers that come with lighter engines, like the OS, LA's tend to have this problem. The first thing to do is to put the battery pack under or over the fuel tank, as far forward as possible. Wrapped well in foam and rubber band the foam in place. You can also do new servo trays and move all of the servos as far forward as possible. Depending on what type of elevator and rudder controls you have, you can go to pull/pull on the rudder with very light weight metal cable and use Sullivan golden rod push rods (all light plastic). For every ounce you get out of the tail you need about three or four ounces less on the nose. Moving the engine forward some will also help, so take the easiest things to do first and keep checking as you go. I just took over two pounds out of my 33% Extra (from 25 pounds down to 23 pounds) what a difference. The absolute last thing you want to do is to add weight. The lighter the wing loading, the better it flies and responds.

Hope this helps, any questions you can email me at [email protected]

If you need that much weight to make it balance, maybe the best thing to do is lift the engine up 3 inches.....................then drive another plane under it!!!!

You all have to understand how badly/cheaply this ARF is put together. I mean, I only paid like $60 for mine and that was from the LHS. It has foam sheeted wings, and heavy ply for the fuselage. It is sturdy however as I found out. I was flying inverted and was distracted by my grandaughter and it hit the strip at nearly full throttle. The only damage was the wing snapped in half at the joint and the motor ripped out of the mounting rails. Other than that it was undamaged. I retired mine some time ago, but it's still hanging from the ceiling until the wife is ready to learn to fly...probably this summer.

WOW,

Thank you all for the advice.

I already have the battery under the tank, I will consider moving the servo tray forward. The previous owner used heavy nuts and bolts to hold the servo horns on the rear control surfaces I will replace those with lighter ones. AND...there is quite a bit of epoxy in the tail; I will, very carefully, attempt to sand it off

This one has a balsa wing and seems to be of fair quality for an ARF. I will do what I can to keep from adding any weight.


Crashem....if you are sure about the 3 1/2 inches, that may be more than 1/2 the problem. I have no manual and was assuming 2 3/4 inches. I was guessing based on where I think the wing spar is. (Its balsa sheeted, so I can't tell for sure).


Thanks again!!

Agexpert,

I have my construction manual here in front of me and here is what is says about the CG:

"The center of gravity is located 3-1/4" back from the leading edge of the wing, at the duselage sides. This location is recommended for initial test flying and trimming. There is a 3/8" margin forward and a 1/4" margin aft. It is not recommended that the center of gravity be located any farther back than 3-1/2"."

Also, here is the information on control throws:

"Test Flying and Training"
Ailerons: 3/16" up 3/16" down
Elevator: 5/16" up 5/16" down
Rudder: 5/8" right 5/8" left

"Advanced Training"
Ailerons: 3/8" up 3/8" down
Elevator: 1/2" up 1/2" down
Rudder: 7/8" right 7/8" left

Here's a pic of mine taking off on it's maiden flight

That's her!! er umm....IT!!

Cool, thanks for the info!! I may have a smaller problem than I first thought. My assumed 2 3/4" is waay forward of even 3 1/4 or 3 1/2".

Thanks for that information, I spent hours looking for it and never found it.

Now I will see how much adjusting is needed after I move the CG machine back a few clicks.


Thanks Connery for taking the time to look that up.

NO problem That's why we are all here.

I don't see that you ever said what motor you have installed in it, but I have a OS 40LA in mine and it flys like a brick. Hopefully you have something a little more powerful than that to fly it with.

Agexpert, Wait Connery mentions that his has foam core wings and Heavy plywood for the Fuse. The Right flyer 40T I have is constructed exactly like other built up models the wing is not foam its balsa and the fuse is lite plywood if I had to guess and I amm I'd say it weighs around 5lbs. We might not be talking about tthe same plane I beileve global made it and hobby people sold it you could check there web site for a manual. Mine is setup too fly I'll balance it this weekend and post the numbers.

Crashem,

You might have the MK I instead of the MK II. The MK II that I have is definately a sheeted foam wing. The way I found out for sure is when I joined the two wing halves, I drilled a few small holes in the end caps for each side for the epoxy to key into and found that on the other side of that thin plywood was foam.

Well,

Let me wipe the egg off my face. My plane has a balsa sheeted wing which is likely foam. It is the same plane as connery has. I have not checked the balance yet, but I suspect it will be much better than originally thought. I will fly and trim it within 2 wks or so, (schedule permitting).

I am learning...but when you have a pre-built plane, it actually makes things harder, not easier.

agexpert,

NO egg on your face, RCU is here to help avoid that.

I am a newbie, so I know how you feel.

If you had not asked the question, then it might have been different, but only you would have known.

Dave

Don't do any grinding or modifying until you know if it is needed.