I have attached three pics. I think I'm tail heavy and was looking to get some opinions. A friend built this plane and I had to fix up some stuff. I took it to the field tonight and realized that I forgot to check the CoG. I picked it up and put my fingers about 12 inches each side of the fuselage and on the support beam that goes across the wing (I forget the proper name for it). Anyway, it seems to hang down at the back (tank empty).

I through a bar of lead weights on the front where the engine is (pic shown) and it seemed to level out a bit.

Can someone please give me their opinion?

i just helped someone at my field with that very plane, it balanced on the back edge of the main spar, . i didnt fly it but watching it fly i wouldnt go back much farther for training purposes. it needed some down elevator trim to make it fly strait and level.
that was with a magnum .40 gpa engine, similer to your os .40 fp (i think thats a 40 fp))

Yup, I think you're right, it looks a little tail-heavy to me. Before you add weight to the nose, see if you can get a better balance by moving the battery pack forward inside the plane. If that's not enough you might be able to add a 'heavy hub' to the propeller shaft. If you do add those weights, make sure and coat them with epoxy or CA after you stick them on, so that the fuel doesn't get to the adhesive and make them fall off in flight.

Jim you have surmised correctly that the airplane will only be in balance at the point you select if it sits level. The 'support beam' is the main spar. Most airplanes especially trainers will have the spar at the quarter chord (aka 25% mac, mean aerodynamic chord) and this is the ideal position to balance your airplane.

The lead is OK but as others have said sometimes other shifting of components is helpfull. Such as if you do not already have the battery all the way forward behind the firewall and under the fuel tank then I would suggest doing so rather than the lead.

Enjoy your maiden.

John

the 40 la and fp are some of the lightest 40s around....im sure when your kit was designed they did it around the heavier engines at the time. Mount the engine as far forward as possible, and mount the battery pack as far forward as you can, and use a heavy prop hub , i think Harry Higley makes them

that plane isnt mine, i do agree that it is tail heavy, all i was stateing was that i wouldnt go farther back then the main/support spar.
so if you are farther back than that dont fly it. (i set up my planes where i read is a good spot on rcu, then add weight for the maiden and remove it as i feel comfortable)
if you really need that much weight, you could buy a ax46/magnum.46/gms.47/ect and you wouldnt need the weight

Thanks for the help guys... I do appreciate it.

The battery pack is already ALL the way to the front it can go. It is under the fuel tank and right behind the firewall. I even changed batteries which I assume is heavier now (2700mah vs. 500mah).

I was concerned with the weight of the plane after attaching the lead. I didn't know if my .40 OS was going to be enough to get it in the air after that. But, it seems the concensus is that I should add them, so I will.

Note: It was the main spar that I was on, I just couldn't think of the name of it.

Question: Attaching the lead - Should I remove the adhesive and attach it with CA? If I use Epoxy, I'd probably never be able to remove it if I get a new engine or something, right?

jimmyjames213 my reply was to the OP jim.thornton and for whats its worth was not in any disagreement with you.

jim.thornton by the way did I mention your airplane looks great and I applaud you for your care in preparation. Yes when attaching weights do not depend the sticky to hold them they will come loose sooner if not later. Epoxy or a good ca job. Its simple in that airplane to just install them around the tank somewhere.

For what its worth with some problamatical airplanes which yours is not, is to even mount weights forward in the engine area. Have even mounted batteries forward under or to the side of engines in boxes fabricated to do the job.

John

You can still get epoxy off with a knife. But whatever adhesive you use, coat the lead and the area near it with a light wash of epoxy to fuel proof it. If it's possible, put the lead someplace where it will stay without glue, then use the glue to hold it there.

For what its worth if one chooses to use lead there is an easy alternative source which is automobile tire weights and usually can be had for the asking. The advantage over the commercial stick ons is the chunks can be hammered on a vice or anvil in seconds to a paper thin consistancy then if you want to trim weight its easy to just use scissors.

In this condition the lead can be wrapped around stabilizer struts and a bit of thin CA bingo it disappears or moulded, shaped or applied just about anywhere such as a cheek cowl, here is a photo of a 50 cal musket ball shaped in this way.

since its on the main spar, add the weight at first but keep it on the outside of the fuse. then as time progresses take the weight off a little at a time.

Thanks for all your help guys... I have split that bar of lead in two and have mounted it under the engine on each side to keep it even.

I have glued it with Medium CA glue and have put a bead going around it too.

Should I also give it a light coating of epoxy?

I would

jim add a spinner and see how it goes....then add little weight if is necessary.

Regards,

If you use a heat gun on the epoxy, it will soffen it enough to get the wt back off.

You want to ad usefull weight? Install a Super Tigre 45 with the adjustable muffler. Plenty of power too! Also if you ad lead try mixing BB shot with epoxy and lay it in the nose out of the way of the engine and mount.

just go to lhs and get a harry hingley 2 1/2 oz heavy spinner nut and most of your problem will be gone and then later if you want it to be more tail heavy just replace with a lighter one or remove completely.

BIGACO

Hey man I would say to try and move as much stuff forward as possible.. such as your battery pack first.. then your reciever see if that helps out at all

Okay... I'm back, and happy to say that the maiden flight was a success. I was quite nervous and my heart was pumping through my chest because it's been about 5 years since I last flew. On top of that, it was my first ever time taking a plane up that has never flown before so I had no idea what to expect.

My first flight I did about 5 or 6 take off landings along with some circuits and procedure turns.

MAN, I CAN'T BELIEVE I STOPPED FLYING FOR SO LONG IT'S SO EXCITING!

My second tank was a little different. I did a few more take off/landings and I started getting much more comfortable again so I through in a roll. The plane seemed to really struggle rolling, in fact, I had to put it into a slight climb. I don't remember my old Eagle 2 being that sluggish but I also had a .46 OS on that so maybe that was the difference.

Well after the roll, I did another couple landings and they were getting a lot smoother (I was just floating onto the ground). I got up enough nerver to go for a loop. I maid it to about a 45 degree angle and I realized there wasn't enough power to do it, so I bailed out. I climbed up quite high and I turned down wind and decended (fast) to gain speed to try another loop. I got to a verticle position and boom, the engine quit and was forced to dead stick it. It came in nicely, I fired it up again and richened the mixture, this time on the ground I put it into a full verticle (not just a 45 degree) to make sure that it wasn't going to quit on me again. I took off, did half a circuit and boom, the engine quit again. I was forced to do another dead stick I figured I ran out of gas this time. It survived and I decided to call it a night. After I took off the wings I noticed that there was still about 5/8 of a tank of fuel. Huh?

I go through all this because I have taken another picture and I was wondering what you guys think. Do you think the problem of the engine quitting could be caused because the fuel feed is looping too high (above the top of the cylinder head)?

And... I'm thinking I might need to change the prop? I have a 10x6 on it now but I have an 11x5 in my kit. That should give it more "pulling" power right? Should I change it?

Mike31: Thanks for the suggestion, but I will never buy another Super Tiger. I bought a .45 about 6 years ago and I spent about 15 hours trying to tune that thing. I had the *pros* at the field trying to tune it for me (VERY experience precision flyers) and the thing would never run for a full tank. EVERY single time up, it would dead stick on my.

As for the spinner, I'm looking to spend as little as possible at this moment and I already had the weights so I figured I would just do that.

Good heavens shorten that fuel line it should go right along side the cylinder. The fuel nipple should point almost straight back close to horizontal.

Absolutely. Also check the clunk and line to make sure it's not bound up in the front of the tank.

ditto

That's what I thought. The nipplie is straight up right now, so I will turn it too.

The clunk is fine, I've taken the whole tank out to make sure that he had everything right in there.

Appreciate the help!

It probably doesn't matter for you since you've sworn off ST's, but in case you run across someone else with the same problem maybe you can help them out. I have three ST 2 strokes (2x40's and 1x61) and they all did the same thing to me at first. The trick to making them run nice is only run them on 5% nitro - they really don't like or need more than that - and replace the stock plug with an OS #3 plug. Then it's just a standard tune up procedure (low and high speed needles) and they'll idle all day and transition like a dream.

Buy a new engine to set the CG????