Wes Huff

I have not built many planes, and no gliders, and therefore the basic question. I have just assembled a 2 meter called the Sonet. Built-up wing and fiberglass fuselage. The kit is convertible to electric, but I did not (which may be the problem). The problem; the plane is very tail heavy. I’ve got 4 oz.s of lead in the nose and a large battery pack and it is still very tail heavy. How much lead should I have to put in this thing and what is the best way to do it?
Thanks in advance to the Master Builders.
Wes

jetranger-RCU

My Feedback: (1)

I saw this done once take split shot the lead they use for fishing put what you need in the nose for blance or any scraps of lead now the tricky part melt the lead put the nose of the glider in ice water only if it is fiberglass now pour small amounts of hot lead in let cool add the rest the same way when finished put some thined out epoxy over the lead so it flows in any gaps between the lead and fuse only a little is needed just be careful you do not want to melt the fiberglass also make sure the water has ice cubes in it not just cold water

probligo

I presume that you are trying to get the CG to the point that is shown on the plans...

DO NOT under any circumstances pour molten lead into fiberglass. The heat from the lead will destroy the inner fibreglass long before the effect of any external coolant is felt. If you want to use lead shot, pour epoxy into the ballast box once the correct amount of lead has been added.

BUT BEFORE ALL THAT -

Ok, if you can, move the battery as far forward as possible.

Next step, use a bigger battery set.

Move Rx and Servos forward.

Still tail heavy?

Rebuild tail feathers with lighter stock and covering

Remove all paint from wing back.

Still tail heavy?

Buy 1/4oz mag wheel balance weights from your local tyre shop. Use these for your ballast. The adhesive tape will stick to anything, just once. They are cheap, compact and WORK. Stack up the raw sticks on the nose while you get the balance somewhere near right. Then strip off the backing tape and lay down in the bottom part of the nose. As the glider gets close to balance, start adding smaller sticks down to individual squares. Leave the glider just a tad nose heavy (one more rather than one less 1/4 oz)

The overall weight of a 2M should be (from a kit anyhoos) somewhere in the vicinity of 30 - 36 oz ready to launch. Good timber selection and building can get that below 30oz without too much difficulty. But if you are looking at getting down to 20oz or below then you will need to look at some fairly sophisticated building techniques and you will certainly not get the materialks with a kit.

Rob Glover

Wes -

Every plane is different, don't worry about how much nose weight it takes. Just make sure that the CG is right before flight. You may be able to sneak the CG aft with some test flights, but don't worry about that until you are sure that it's gonna fly.

As far as pouring molten lead into the nose, I do it pretty regularly and have never had a problem. Lots of folks freak out about it, but it works for me. I am properly equipped to do so. Please don't try it if you aren't set up with a safe place and proper equipment. Molten lead gives off noxious fumes and will burn the devil out of you if it spatters. If you have any moisture in the nose of the fuselage when you pore the lead in the water will flash to steam and splatter lead somewhere. Don't ever say that it won't work, because it will work well if you are careful.

It's easy enough to get a 25 lb bag of lead shot, or some old tire weights. Most planes have enough room to stuff lead. If you want to try something fancy at a lower temperature you can go to McMaster-Carr and get a pound of Cerrobend for around $30, it melts at 158 deg F.

have fun - Rob Glover

Jeremy Sebens

Pouring molten lead into figberglass may work for you, but I wouldn't recommend it to a beginner. Actually, I wouldn'e recommend it to anyone. Maybe with a single layer layup you could get away with it, but the heat transfer through f/g is much slower than through the lead - so I concur with probligo. In a multi-layer layup, you're going to wind up transitioning the epoxy, and the stresses from the thermal gradient will almost certainly delam the nose section. This may not be noticeable since the lead is now a part of the structure, but I still don't like the idea of destroying structure to add weight. There are much better ways to go about it. My favorite way to add weight permanently is to use lead shot and Pro-Bond, which will expand and has some resilience, so the nose ends up very tough.

Wes Huff

Thanks very much for the suggestions. I think I'll go with the lead shot. Sounds easy.
Thanks again.
Wes

drela

Instead of pouring molten lead into a fiberglass fuselage, you can use a casting mold made out of 4-8 layers of aluminum foil. Pack the foil on the ouside of the nose so you have a nose-shaped cup, prop it up in a small metal or glass container, and pour the lead into it. The lead weight can then be glued into the nose. It will be slightly oversize by the thickness of the fuse shell, but this should not cause a major fit problem inside a typical bullet-shaped nose.

For small weights, such as for HLGs, I find that plain solid solder is more convenient and safer than lead. The 1/8" diameter solder used by plumbers is good for this. I first weigh out the right amount of solder, and drip it into the aluminum mold using a soldering iron. Then I dip the iron into the mold until all the solder fully liquifies to get a solid casting.

Ollie

I've poured molten lead into over a dozen fiberglass and epoxy fuselages over the last 15 years. These fuselages were made by the lost foam method using over a dozen layers of 1.4 ounce cloth. the layups were from 1/32 to over 1/6 in thickness. When pouring the molten lead, the nose was in room temperature water. This is an inherently dangerous operation but with care I have never had an accident. Still I do not recommend it to others. It should be done in open air, with heavy gloves and eye protection. I do want to set the recors straight about damage to the fuselage. The fuselages have survived being planted to the wing in crashes and have withstood this abuse. I must conclude that the molten lead only hardens the glass-epoxy layup rather than damaging it. Those people that think otherwise are wrong by my experience.

Gary Retterbush

As Rob and Ollie said, it is possible to pour molten lead into a FG fuselage but it is NOT recommended. It does not damage the fuselage. I have gone to using a "baggie" and sticking it into the nose and adding lead shot until it is right. Put a few drops of CA or epoxy on it and seal it up. An almost perfect fit and easy to remove.