Foam Core Board for larger rockets

Since I'm slowly mutating into a cloner and upscaler, I've got a few biggies planned. One is a 1.68x Estes Blackhawk (the old Centuri Buck Rogers Starfighter) and another is a 1.68x Estes Pegasus. Since both of these models require "airframe" structures originally built out of cardstock (B'hawk) and Balsa (Pegasus) I was wondering about the suitability of foam-core board used in signmaking. I'm thinking 3/16" with a basswood stringer around the edges where required.

I'm not planning on sticking a 29mm mount in 'em but a milder 24mm (E) so they don't necessarily need to be glassed if they're designed and built well enough (also I've never glassed anything before and don't really want to try just yet).

Anyone have any success/horror stories or any other experience using foam-core as a building material?

Jeff K

It should work in theory.

Do be aware that a lot of glues will dissolve the foam sheeting. Super glue and epoxy will for sure. White and yellow glues should be ok, but you'll want to test them first.

I have used foam core extensively on low, mid and even one high power rocket. I have made numerous centering rings out of it, and several sets of fins.

This one was built with foamcore and a posterboard shell. The original only had a long 29mm tube. However, it died from lack of ejection, hence the "son of" which follows. The new version had a 4" stuffer tube throughout.

In other fin applications in mid and high power, I used dowels on the leading edges as the fins were quite large. I have no pics, but to get an idea of the sizes you can pick out the Rsims for the Beer 'n Pretzels, Beer 'n Pretzels II, and Carrot Top rockets [here]

I mostly used carpenter's glue on these rockets, but also have used epoxy and polyurethane glue successfully.

I'm not real familiar with the designs you are talking about, but hopefully this helps you make a decision on the foamboard.

Oh I forgot myFireball XL5 The fins are foamboard with some internal reinforcement.

I have successfully used foam core board as centering rings and thrust rings in a 31 oz 29mm rocket. I used epoxy and polyurethane glues without a problem. The paper surfacing pretty much keeps the foam away from the glue. I am currently building a six inch diameter 29 oz stubby rocket with foam core rings and a reinforced bulkhead. Actually, the ejection charge will be contained inside half a Pepsi can epoxied to the underside of the foam core. Holes are placed around the outside edge of the bulkhead, and a piece of dowel is epoxied across the top to brace it. It will be ready to fly by the end of the month.

Excellent. I figured the material could be useful and it's much less of a pain when finishing than balsa. I also like that you can use it more efficiently as it is essentially grainless and you have that much more flexibility in laying out the parts.

I think the first use of the board I will make will be in the Pegasus as it seems a bit simpler than the Blackhawk. Also, I just finished redrawing the decals (another part of this hobby I've been strangely drawn to).

Pics will come as it's built and any additional tips or hints are most welcome!

Jeff K

Oh, I forgot to add, Dick... your Fireball XL5 is gorgeous. I'm truly inspired by it!

I've used foam board for CR's many times, its works really good, I haven't made them for anything larger then 24mm.

Check out my 3x upscale of the Centuri "Buck Rogers Starfighter". The larger fins are foam board laminated with 3/32" plywood. I used basswood strips for the fin edges. The vertical fins are fiberglassed basswood. The cockpit is formed from foam board and is removable to gain access to the altimeter. This bird is 44" long and weighs 5.5 lbs. w/o chutes and motor.

I still need an additional 48" PML chute and the courage for the maiden flight on an H-180.

I'll post pics of either the carnage or me smiling from ear to ear after the maiden flight.

3x Starfighter 1
Aft End Pic
3x Starfigher Pic 2
Another one

Truely outstanding....er...well....at least if it flies Can't wait to hear the results! Foamboard rules!

BTW welcome to the group. If this is any indication, you will be a great asset here!

I've used foam core for centering rings and fins for years, for rockets up to 12 inch diameter(granted, the fins were framed with 1/2x1/2 balsa symmetrical leading edge material and covered with two layers of 12 oz f'glass on the biggest ones), and I've always found it satisfactory. Attach your recovery harness on the outside of the body to lower the airframe nose first to avoid fin damage on landing, though. It also works really well for big double delta boost gliders.
-Braz

Jeff, that is the exact same board my frined used locally for his 6 foot tall Level 3 Pyramid...it withstood the power of an Aerotech M2400 Blue Thunder and flew well!!!

He did glass it but it is cheap and good stuff...let us know how you do on your project