Parts ordered

[Jase]

Since the Sparrow construction is finally getting within sight of completion, I decided to start a scratch build rocket.

I ordered parts for a scratch built design today. the body tubes I get from work. they are 3.25" OD, 3" ID and 30" long.

I'm going to use a PML 3" Nose Cone, 29mm MMT, Plywood fins if I can ever get to the hobby shop to get some.

For now, I'm going to keep it simple (although, I'm going to do a 6 fin TTW configuration that should be a challenge).

Attached is the Rock sim file for it. If you see something I'm missing, let me know!

I'll keep everyone posted on the construction.

Jason

 

[PGerringer]

Go man! Go! Don't forget to think H128...

 

[MarkABrown]

Looks very cool Jase. I really like the fin design that you came up with. Check your simulations again though. I think you're going to need a bigger chute. It's landing at about 29 ft/sec. Ideally, you want to get that figure down to around 15-17 ft/sec.

 

[rstaff3]

Ditto on the fin design!

 

[Jase]

Here are some pics of the scratch that I'm doing. I'm still working on a name for this bird.

The fins are my own design. I cut them out of 1/8" 5 ply aircraft plywood.
The nose cone is a PML 3" cone (a lot longer than I expected)

I'm going to use 1/2" kevlar for hte shock cord it's epoxied to the MMT already.

The body tube is a 3" ID, 3.25" OD 30" long core that I got from a roll of vinyl from work.
all parts

Here's the slots that cut from the tube with my dremel tool. if you stack 3 cutting discs, you can get about 1/8" slots easily!
fin can slots

It's a six fin design. I drilled holes in the fin tabs to allow the expanding foam flow through when I get to that point.
fins and tube

Here she is dry fitted together.
dry fit
standing

here's a close up of the fin can
fin can

More to come! I'm hoping to have her finished by Whitakers on the 27th for a first flight!

Jason

 

[MarkABrown]

Jase,
I gotta tell ya again. I love that fin design! That is going to be one cool looking rocket!

 

[Austin]

Absolutely fantastic job there Jason! You sure have come a long way and I can tell you asked the right questions by the high quality of design and construction you have done so far. Keep up the good work and the pics...we LOVE pics here!!!

Carl

 

[PGerringer]

Very very nice, dude. Hey, I hope that is a 29mm motor mount for your H128.

 

[Jase]

Got the fins tacked in this afternoon with CA. will fill the fin can with PML's expanding foam either later tonight or tomorrow.

One question: When filling the fin can with foam, is it better to pour the foam and just let it go over the top and carve it back down or is it better to pour it and then jam the aft centering ring in place to keep it inside?

As far as I can tell, this bird will fly at Whitakers on the 27th. it probly won't have any paint on it, but won't be the first time a bird's flown nekkid.

Jason

 

[rstaff3]

You definately do NOT want to confine the foam! Having it run over a bit has not been a problem for me. Too much can be messy, but it usually tends to go upward rather than spilling over and gunking up the side of the rocket. If it does that, it can be sanded down once dry. The excess can be easily cut off. You generally should mix small batches and go slowly until you get a hang for it. However, the gap you are filling is not terribly large and it shouldn't take much raw foam.