29mm Upscale Astron Sprint

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Jan 17, 2009
Reaction score
To begin with I wasn't sure where to put this 'cause this is going to be a 29mm bird and will probably only fly on SU F's or G's at the most but...

It could take a 29mm "H" or "I" and I am Cert L1 but since I don't have a reload case for that motor anyway we will call it a mid power.

Or I coulda put it into "Scratch Built"...

Nevermind...it's here now!

I have made some part sets for two members here for a 29mm upscale Sprint and in the process I kinda messed up a set (nose cone and tail cone). I say "messed up" but really they are good parts just not "commercially acceptable".

In other words NOT good enough for a customer but good enough for me...hey I wouldn't throw them away!:D
The only problem is the nose cone shoulder is a little small and needs some masking tape (no big deal!) and the tail cone 29mm motor tube hole is a little oversized (again nothing a little extra epoxy wont fill).

I have all the parts cut out and as soon as I finish sanding the fins I will post some pics.

Sorry guys but my workbench is a MESS so I gotta clean it up first. As soon as that's done I can take some pictures.

Say anybody know the delays and impuse #'s available for a 29mm reload "H" or an "I" so I can do a SIM...just for fun?
The delays and motor impulses should all be in Rocksim, but usually the delays for most of the HPR motors are 6, 10, and 14.

I got the fins rough sanded last night and this morning early.

I also layed out the parts for my 3x24mm cluster Speint (from a different post.
The fins are made from 3mm plywood I got from a box of liquer filled chocolates (they were my father-in-laws favorite and he always saved me the boxes.)

I then laminated 1/8" balsa an each side then rough sanded the airfoil profile on my bench beltsander.

I'll finish with hand sanding.
Here is the 29mm tailcone and motor mount parts dry fitted.
Finally the 3x24mm cluster tailcone ready for primer...almost.
Slight delay...I have to make a bunch of CRAYON nose cone for somebody!:rolleyes:

Story of my life!:D
...then rough sanded the airfoil profile on my bench beltsander.
Beltsander :confused: :confused: :confused:

Cheating. I think that's probably definitely possibly cheating. :D

Well, I wasn't getting a good finish when I tried my chain saw:D

Unfortunately...I don't have any fingeprints left.:eek:
Well, after a busy work week and finishing a good size custom order. I finally got back to it.

Just worked on the 29mm version. Maybe tomorrow I'll get on the 3x24mm cluster vesion.

Not a lot of time on it tonight but I got the fins on, fillets made and the first coat of filler on the fins.

Now sand sand sand!!
Originally posted by sandman
Now sand sand sand!!

But you're so good at it!!!!!!

Seriously, it is good to see you working on a project for yourself. You do so much work making parts for us, I was beginning to wonder if you actually flew rockets or were just a parts manufacturer.........:D
Well, I started priming the Sprint and ran into a few problems...let me vent.

My local hardware store use to carry Bondo brand spray primer and I just loved the stuff! It drys fast, fill great with lots of "filler" in the paint.

Unfortunately my local hardware went out of business so I went to Murry's Auto Parts and got some Dupli-Color Filler Primer with "High-Build Formula! Sounded perfect, right?

Well, it would be if it only came out of the dumb spray nozzle!:mad:

Every time I cleaned the nozzle it would "spray" for maybe...2 or 3 seconds.

I shook the can for a minimum of 5 minutes to make sure it was mixed (rattle can), kept it in the house all night to make sure it was warm, even ran it under hot water still...frustrating as "H" "E" Double Hockey Sticks!!!

Finally out of shear frustration I did what it always tells you on the can NOT to do...I stuck a pin in the spray nozzle and made the hole bigger.


Don't always believe the dumb can!

Let me put a few coats on do some sanding and then a few more coats before I take more pics.

Man, I just love this design...so aerodynamically clean...and the fins have that nostagic WW II airplane shape!

Although in reality when you Sim it...all the tailcone and airfoiled fins and parabolic nose cone give you is maybe an extra 50' of altitude.:rolleyes:

I guess those nice aerodynamic features only matter when you travel several thousand feet...not 1'100'.

That's OK...it looks pretty!;)
More primer problems!

I finally got the can to spray properly but I still had to cleat the tip every few sprays...a real PIA!

Then near the end of the priming...the friggin' can goes crazy...it wont stop spraying!!!

Honestly...like the spray nozzle was jammed...even pulled the nozzle off and the can keeps sqirting into my makeshift spray booth!

I hope I just got a bad can...well, yes, it WAS a bad can...there is still some left in the can and I do have some "spots" to touch-up after I wetsand but in general it's basically primed.

I do have another can and I hope this next one isn't quite as pathalogically possessed!:rolleyes:

I really like the paint. It covers real whell (when it comes out of the can) and smooths out real nice (when the can stops spraying) and it sands like it should with wet/dry.

Hopefully it will be ready for paint tomorrow!
Originally posted by sandman
Well, I started priming the Sprint and ran into a few problems...let me vent.


Unfortunately my local hardware went out of business so I went to Murry's Auto Parts and got some Dupli-Color Filler Primer with "High-Build Formula! Sounded perfect, right?

Well, it would be if it only came out of the dumb spray nozzle!:mad:

from your picture I see you used the gray primer. I have a can of the Dupli-Color oxide red sandible primer sitting on my paint shelf. Hopefully that was just one bad can and not a common problem.:)

If the rain stops here I'll try to use it tonight and I'll let you know tomorrow.
We had some good weather yesterday, good enough for painting anyway. I got out the Dupli-color and gave some of the unpainted birds a couple of coats each until the can ran out.
No problem. I think you just got a bad batch.
Sandman, that looks truely awesome! Keep up the good work :p You sure know how to fill balsa :D
No problem. I think you just got a bad batch.

I believe so. The second can worked just fine.

I do have some teeny tiny spots to fill yet...been busy but color should go on real soon.
Sandman, This is VERY inspiring!!

I just love the way this rocket dwarfs your mega caliper!!

I cannot wait to see it finished!!

I finally am getting started on mine Gordon....

I went with TTW fins on mine. I notched out a 1/2" long slot in the tail cone shoulder so the fins should be bulletproof. I'm using 1/8" thick lite ply and then a layer of 1/16" balsa on both sides...root thickness will be 1/4"....1/8" at the tips...airfoil sanded into the cross section.

Here are a couple of pics...
The fins are all sanded now. Here's a couple of pics of the dry fit fin can with TTW and notched into the tailcone shoulder.
Hey Gordon...

Have you run a RocSim on the 29mm version yet? I'm wondering what engines/delays will work best. What size parachute are you thinking of using?

This thing is going to SCREAM!

Looks good so far!

I made the same motor mount! I guess we didn't need plans...we made 'em the same anyway!

I've been really busy on...a secret project...so I've let this sit hile the paint cures a bit.

I think it need a little more wet sanding with 600 grit then a final coat then some decals or somthin'.
According to rocsim a 7 sec delay is a about 1/2 sec too long with an F20 econojet.

A G35-7 econojet is only .17 too short. but I think it'll work just fine!