Estes Astron Sprite, The Original Gene Street Design Circa 1966

[lakeroadster]

There was a lengthy discussion about the Astron Sprite over on the Vern's Astron Scout @ 2.13 Scale? thread.

I felt it prudent to start this thread, such a historical rocket design deserves it's own thread.

 

[trialsguy]

That’s one of my favorite rockets, for decades. Maybe I should finally build and fly one this year? ;o)

Also - In the early black and white ad (top) , what colors do you imagine it is? I’m thinking bright blue and yellow.

 

[lakeroadster]

Also - In the early black and white ad (top) , what colors do you imagine it is? I’m thinking bright blue and yellow.

Probably White / Red, or White / Black. Estes pretty much stuck with those colors on the initial entry level rockets.

The 1st color photo of an Astron Sprite appears on page 21 of the 1971 Estes Catalog. See photo's below.

Here's some more interesting reading too... Vern Estes Patent No 3,114,317

 

[bjphoenix]

I remember a time back in the 60s when you could get one of those kits free with an order of a certain size.

 

[Mugs914]

I always liked the Sprite. I built a few back when I was was a kid, but never did fly any of 'em.

Probably should correct that!

 

[Wally Ferrer]

Definitely a favorite...

 

[Grant_Edwards]

Here's my 50+ year old Sprite. I don't remember if I paid for it, or if it came free with an Estes order. I've been meaning to figure out how to launch it again. It's the only one of my 50-year-old fleet that didn't require repair work when I unearthed them a couple years ago. The Astron Sprite required short 18mm engines which are no longer available. I suppose cutting off the top off a 1/2A 18mm engine is against the rules. Maybe I can make an adapter for a 13mm engine?

 

[Tobor]

Here's my 50+ year old Sprite. I don't remember if I paid for it, or if it came free with an Estes order. I've been meaning to figure out how to launch it again. It's the only one of my 50-year-old fleet that didn't require repair work when I unearthed them a couple years ago. The Astron Sprite required short 18mm engines which are no longer available. I suppose cutting off the top off a 1/2A 18mm engine is against the rules. Maybe I can make an adapter for a 13mm engine?

View attachment 508691

You can use an expended 18mm motor casing as a motor adapter. Just clean it out and cut to same length as a 13mm motor. Semroc/eRockets used blank 18mm motor casings in their Sprite Retro Reproduction kit KV-86 (Link).

Recommended Motors: 1/2A3-2T (150'), A10-3T (250'), A3-4T (300’)

You can download a pdf of the KV-86 instruction manual from eRockets (Here).

 

[lakeroadster]

Here's my 50+ year old Sprite. I don't remember if I paid for it, or if it came free with an Estes order. I've been meaning to figure out how to launch it again. It's the only one of my 50-year-old fleet that didn't require repair work when I unearthed them a couple years ago. The Astron Sprite required short 18mm engines which are no longer available. I suppose cutting off the top off a 1/2A 18mm engine is against the rules. Maybe I can make an adapter for a 13mm engine?

View attachment 508691

You might find this site useful.. it has the Estes Sprite S Series to 13mm adapter information. This yields a lighter weight adapter than using an expanded 18mm casing.

All these adapter configurations pull the cg back farther than Gene Streets original design. And the simulations show it is unstable compared to the original.

Adding the base hack trick to the simulation however makes the adapter versions of the Sprite stable.

 

[Grant_Edwards]

All these adapter configurations pull the cg back farther than Gene Streets original design. And the simulations show it is unstable compared to the original.

Adding the base hack trick to the simulation however makes the adapter versions of the Sprite stable.

Is the base drag trick being used to account for actual base drag, or is to account for the ring fin which is missing from the sim?

 

[lakeroadster]

Is the base drag trick being used to account for actual base drag, or is to account for the ring fin which is missing from the sim?

Actual base drag, applicable to rockets with a Length to Dia ratio less than 10:1

But to your point.... here are the simulations. Also note with the motor kicked back the rocket is unstable enabling the "tumbling" recovery.

I had to re-create the adapter in Open Rocket. The sims shown in Post #9 are Rocksim files I pulled into Open Rocket. When I went to re-open the file to do the ring fin hack... the file was corrupted? Not To Self: Stop downloading Rocksim files.​

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[dpower]

Good stuff. For kicks, I weighed an original 1/2A6-4 shorty, and a 1/2A3-4T with Semroc shorty casing (Link), they both weigh 11g. Makes sense, since the shorties have the same I.D. as a 13mm T motor. This is how I fly my Sprite clone.