How light can we build..?

[GL-P]

The real problem is it's going to be round 4-5lbs fully loaded. At least the fins will never come off!

Overbuilding doesn't always include composites. My dad's CAR lvl 3 is 5.5 inches and 20 lbs with a 4 lb solid nosecone! The thing is it's so short that it needs a lot of trim. Only hit about 900 ft on a J360

 

[rstaff3]

Originally posted by DynaSoar
....

Glassing a Fat Boy and putting on G10 fins through the body to the MMT, that'd be overbuilding.

This d'pends of course. For a 38mm Fatboy this might be OK

 

[DPatell]

Yea, whats wrong with G10 fins and fiberglassing a Fat Boy?


Mine is going to get the longest possible motor next time

 

[GL-P]

All you're doing is adding excess weight to an already low and slow flyer. If you are going to put an I in one, just some 1/8 inch plywood and a layer of 2oz glass should do the trick. The fin tabs on a fatboy are pretty big anyways.

 

[rocwizard]

Gonna stick an I435 in there Dan? Plan ahead and buy a neck brace:kill:

If a fatboy is gonna go Mach, its going to need more than 1/8" ply and some 2oz. glass. I wouldn't do it anyways...

 

[GL-P]

Proper use of through the wall fins (like how PML suggests doing interior fillets) and an good outside fillets and fibreglassing should be plenty. The major concern is the transonic region. I did a sim and the rocket would really push through this region. That's much better than cruising at high speeds. Beyond this region it should be okay.

Big fillets are key. Composites aren't very good at sharp angles.

Add a reverse teardrop airfoil. It's the best for high speeds.

I should change that. It should be 6oz cloth.