Sparrow starting to look like something

Well, after a while of getting parts and pieces and supplies, my TLP Sparrow is starting to look like something resembling a rocket.

This is my first attempt at a mid powered rocket and with Mark's help, I changed the motor to use 29mm instead of 24mm, made custom centering rings and used an LOC 2.5" nosecone rather than messing with the paper cap that The Launch Pad provides with the kit.

Also, I've changed the tail cone from the paper thing to using PML's Expanding foam. After the motor mount was secured to the body tube, we used masking tape to create a mold to keep the foam in a cylinder shape. It worked beautifully, so now, I'll use sandpaper to taper the tail cone from 2.5" to 2".

When it's all shaped, I'll be glassing the BT, fins and tail cone. It's coming together nicely!

Very cool, the tailcone foam came out really nice...

That sounds like it will work out well. More pics please!


I recently added a paper cone over the tip of a plastic one and used 2-part foam. I used the printout from VCP, CAed it on, soaked it in CA, drilled a small hole, and poured in the foam. I should redo the cone on my TLP Rapier that way. Maybe someday.

The one problem was getting the foam into a small hole since it tended to clog it up. I ended up wasting a couple of small batches while I figured it out.

Oooh, just looked at the TLP Sparrow pic from his site. Cool rocket! Add lotsa nose weight....

Sorry, rstaff. The pics I made for Mark and Jase were mostly of Mark's Hermes. Here is the pick of the sparrow getting assembled:

https://www.cybergatetech.com/phpgraphy/?display=Rocketry/misc/img_2063.jpg

BTW Jase, I showed my wife the pic of you and your better half working on the Sparrow. She smiled real big and called us all geeks. What did she do that for? I was offended and kicked her real hard in the shins. Then she cried, "I was only kidding." So, I got up from sitting on her.

So he added some wooden spars, then wrapped tape around them to make the mold? A bit more detail please. Thanks!

Ok. for the motor mount/tail cone:

The upgraded motor mount started out as just a tube, 2 centering rings and a smaller CR for the very end.

ftp://ftp.fastsigns.com/s250/outgoing/Rockets/29mm_top.jpg
ftp://ftp.fastsigns.com/s250/outgoing/Rockets/29mm_side.jpg
ftp://ftp.fastsigns.com/s250/outgoing/Rockets/29mm_sidetop.jpg

This morning before adding the foam, I added 4 spars for shape and to make it stronger. See https://www.cybergatetech.com/phpgra...%2Fimg_2063.jpg (that's the only picture of the spars unfortunately).

Once the MM was secured, we used masking tape to create a form for the foam to expand into and I'll be sanding it down after securing the lower centering ring to it. The spars will help me guage depth and angle. (I'll post more pics when they are available). Here's the ones of the squared off foam:

ftp://ftp.fastsigns.com/s250/outgoing/Rockets/foam_noring.jpg
ftp://ftp.fastsigns.com/s250/outgoing/Rockets/foamside.jpg
ftp://ftp.fastsigns.com/s250/outgoing/Rockets/foamsidetop.jpg
ftp://ftp.fastsigns.com/s250/outgoing/Rockets/foamwithcr.jpg

and finally, the pic that sold me on buying this rocket from The Launch Pad:
ftp://ftp.fastsigns.com/s250/outgoing/Rockets/rp_lp_sparrow.jpg

Jason

Thanks for the details. I'll have to try a tail cone this way.

Originally posted by rstaff3
I'll have to try a tail cone this way.

Click to expand...

With the help of a finishing sander with 220 grit paper, the tail cone looks excellent!!

There's a few voids between the bottom centering ring and the foam, but nothing some CyA (after further testing to make sure it doesn't melt the foam) or Epoxy won't fix.

I'll borrow the camera from work tomorrow and post some more pics.

If the CyA works out, I'm highly considering painting it over the foam for extra strength. It's between that and coating with Epoxy. I'd rather do the CyA since it won't weigh as much. Any opinions?

Here's the pics:
Finished tail cone
Finished Tail Cone 2
And another one

Jason

I'd consider using Elmer's Fill-n-Finish for filling the gaps and voids. It's worked great for me.

FnF works great, easy to get and easy to work with. I also love Polyfiber SuperFil (available from Shadow Composites). It's my favorite filler - which reminds me - I'm out of it! ACK!

Jase,

My favorite filler by far is Evercoat Formula 27 General Purpose Filler. It is the only filler I have ever used that leaves an almost "plastic" finish and sands into a "powder" finer than flour. Also, it doesn't load up the sandpaper as bad when sanding.

I have used it for years on R/C Airplanes and Jets and now it's my favorite filler for rockets. A bit pricey, around $6 for a small can, but it will last years. I recently ran out and found more, actually a larger can, at a Marine Shop for $9. It never goes bad either, because it comes with a seperate hardener in a small tube.

Cya,

Carl

btw...great job on the Sparrow!

Carl,

Is the Evercoat thin like a thick primer or more like a thick paste(or some other consistency)? Good for fillets? Could it be used to form a tail cone/transition?

Dick,

Evercoat is like a putty consistancy, thicker and it does have some weight to it. What I like is that it fills pinholes like a dream, yet sets pretty quick. I usually have about 5 mins working time, so I spoon out small amounts with a mixing stick, add the hardener, mix it and start spreading, usually with an old credit card or business card. I would not use it for something like a transition, but fillets are a thought, although they would be a bit heavy.

My favorite part of it is sandability; I have used alot of fillers in my days, but have never seen any one of them sand to a powder like this does! A "pop" of the sanding block on my leg or a towel and the paper is clear to continue again.

Carl

Thanks, I may try some if I run across it. The SuperFil, if you're not familiar with it, is also a paste. Its 2-part with a 2:1 mix. It fills well and sands easily, but not quite to a fine powder. It is light and works well for fillets and is ok for structures such as tail cones. For the latter, Jase's method seems better tho. I have only used a few epoxy fillers, and its the best I've tried.