A7Bldr

My Feedback: (40)

Does anyone have experience installing fuselage formers in the mold?
I think more and more manufacturers are doing it. Do they use fixtures to position each former in exactly the right spot? If so, what do these fixtures look like?
Thanks,
Jim

Ed Smith

Before considering how to locate the formers I would suggest you consider the joining of the two halves with formers inside the laid up fuselage. Depending how many formers there are in the fuselage it can be a real chore trying to get to the seam to join the two fuselage halves. I have tried this procedure, just once. It was not worth the effort on the size of fuselage I had. On a large fuselage where one can get ones whole hand inside it might be easier.

Ed S

Deadstik

My Feedback: (8)

Jim,

I can picture how it can be done, but as Ed said, if you are going to join the fuselage halves in the mold (as I do) it would be really difficult to get the seam line down and not have any voids in the joint. This is my thoughts for vintage pattern kits but in much bigger kits it might be possible. To cut to the chase, when it comes to the firewall, at least on my kits, you don't finish and install it until after the engine is mounted. Perhaps on a large sailplane or a plane with a box engine mounting system it would be possible.


Dan

Carolina Custom Aircraft

A7Bldr

My Feedback: (40)

Interesting comments, somehow it seems the manufacturers are doing it……

One thing I’ve tried is to apply the seam tape to one fuse half using epoxy and cavosil before setting the other half on it. This mixture holds the tape in place.
Perhaps this could be done first, then the formers slipped in, using some kind of holding fixture then add the other fuse half.

The plane in question is a large jet, we (group project) have a long build thread over in the jets forum: http://www.rcuniverse.com/forum/m_29..._1/key_/tm.htm

Jim

Pitts S1S

My Feedback: (9)

Jim,

I'm not exactly sure you need seam tape. If you join the seam with aeropoxy all the way around. put in your formers and join the two halves. The areopoxy will be strong enough as long as you get contact. Its how BVM joins his F-100 wings.

Jeff

SCALECRAFT

My Feedback: (13)

Fuses can be made in many ways, but how many formers do you need??

For example, the CMP arfs use many formers in thier fuses, due to the fact that they use poor quality polyester resin/composite combination. Pic of inside of fuse

The models my buddy and I make have minimal formers (framing) in the wing and fuse. None of our models ever failed structurally. My composite corsair has survived 5 impacts,still flying.

The formers we put in, we take into consideration loads and torque on the airframe and where we will grab the model to start it. Our airframes have composites to add stiffness
where we think it may need it.

So we normally put in a firewall, servo tray, wing bolt plate, and enpinage post on the tail.

Again there are no rules, just consider strength to weight. And we try to keep in mind that we can't make them crash proof yet.

Good luck

Steve

SCALECRAFT

My Feedback: (13)

Lost my pics on last post.

Ed Smith

Apart from the firewall which may or may not support the engine the function of formers is to support the fuselage structure. Formers will support the fuselage sides and prevent the fuselage sides from "Oil Canning". A much simpler, lighter and stronger solution is to use carbon tow. Wind the carbon into a string and apply it vertically in the fuselage sides where the formers would have been used. The picture shows my application. Because this fuselage is a short one only one vertical stiffener is required just ahead of the tail. On a longer fuselage more could be used. It is truly surprising the resulting stiffness of the fuselage using this type of construction. The weight gain is negligible as there is usually enough resin in the lay up to supply the carbon string. The big advantage of this is that there is no obstruction inside the fuselage when joining the two halves in the mold, as both Dan and I do.

This is an interesting subject, so keep the ideas coming.

Ed S

A7Bldr

My Feedback: (40)

The formers that we can't do without on our project support the gear, tail surfaces, engine and various servos. It would really be neat to pop a fuse out of the mold with at least some of the fomers installed in exactly the right place.
Jim

goony

model planes are meant for flying and thats it so unless your doing combat build it as lite as you can

EG mine has survide 5 crashes(then its over engineered to heavy) thats ok for a trainer so they can stick em back together but for the rest of us its just carrying round dead weight
if your using carbon tow great!! but dont twist it into a length of string as your wasting it and adding weight just lay it flat in the direction that you want the strength thats wot its designed for

goony