Considering doing an Estes Astron Sprint Upscale to 54mm Min Dia

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bchaltraw

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I loved this rocket as a kid and was lucky enough to have huge open fields to fly them in and did not lose this rocket the 1st time I flew it. I had started getting parts together to do a fiberglass min dia rocket and I am thinking of going with the classic Estes Astron Sprint. But I am pretty uneasy with the fin length and RocSim shows it stable but will over Mach. Those fins are really long and flutter is a big concern. So tossing this out there for thoughts. What say you?
 

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IMHO, it's not a Sprint, without the boatttttt tail. :)

Just looks like a tube with Spitfire wing shape fins.

Roy
I agreed, I was thinking of using a boattail retainer. :) Then I will not have the joy of trying to make the cardboard one of the original the right shape by dragging it over the edge of the desk as I did back in the 80s!
 
I did one with a 29mm. I maybe should of gone 38mm with electronics. A 54mm would be awesome. My boat tail is a little longer than it should be but that's how it turned out.
That looks awesome! I have a GPS, and all of the dual deployment items, the Min Dia AeroTech mount, thinking G10 Fins or Carbon, and a Fiberglass body. Nose Cone to be right I may have to use foam and build myself or I have club members with 3D printers.
 
That looks awesome! I have a GPS, and all of the dual deployment items, the Min Dia AeroTech mount, thinking G10 Fins or Carbon, and a Fiberglass body. Nose Cone to be right I may have to use foam and build myself or I have club members with 3D printers.

If you're going that far, maybe think about foam core glass/carbon skinned fins that taper in thickness from root to tip.
 
Can’t wait to see it. Sprint was my fave as a teenager. I want to to an upscale but maybe not that big
 
Making progress on this, decided to not go Min Dia and go 4" instead. That makes it so every engine other then a massive one does not push it over Mach. This will make it so I can do dual deployment with my already built e-bay and not have to worry so much about fin flutter. With a J140 should go around 8500 ft, which is plenty far. Only engine that would push over Mach is a K570 so I should be good to go. Next up ordering parts!
 

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Finally doing a 38mm upscale. It has 3.1" bt, boat tail retainer (aluminum), 3d printed elliptical nose cone. I made the fins out of 1/4" birch plywood. Rocket is 48 1/4" tall.
Still in progress.
 

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Two scratch-built XXXXL Astro Sprints for a drag race on J295s. Custom 3d printed nosecones, GPS's, 1/4 plywood fins, LOC tubes fiberglassed. If you want this fin set, contact Dave at alwaysreadyrocketry.com. He worked with me to perfect the fins and cut them for me, and get some Blue Tubes for your next build while you are there!

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My boat tail will not be scale. But hopefully it will still produce good results. I am a bit worried now that I have read about boat tails needing to be at more than 0.5 caliber. Mine is likely right at 0.5. :(
 
Two scratch-built XXXXL Astro Sprints for a drag race on J295s. Custom 3d printed nosecones, GPS's, 1/4 plywood fins, LOC tubes fiberglassed. If you want this fin set, contact Dave at alwaysreadyrocketry.com. He worked with me to perfect the fins and cut them for me, and get some Blue Tubes for your next build while you are there!

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Sweet! Growing up, the Astron Sprint was my favorite Estes rocket.
I'm currently designing a 7.5" Sprint for a Level 3 attempt (after I recertify L1 and L2, first 😉). The big challenge I see is getting an upscale version of that lovely ellipsoid nosecone. How did you do your 4" NC?
 
If you're going that far, maybe think about foam core glass/carbon skinned fins that taper in thickness from root to tip.
Good idea. And also taper from the 50% middle of the chord to the LE and to the TE, like a diamond shaped airfoil. Those are good for Mach.
 
Sweet! Growing up, the Astron Sprint was my favorite Estes rocket.
I'm currently designing a 7.5" Sprint for a Level 3 attempt (after I recertify L1 and L2, first 😉). The big challenge I see is getting an upscale version of that lovely ellipsoid nosecone. How did you do your 4" NC?
Do you have access to a 3D printer? If so I can ask for the file so you can upscale it even bigger.
 
Do you have access to a 3D printer? If so I can ask for the file so you can upscale it even bigger.
I do not have access to a 3d printer... Yet.

What price level of 3D printer would be adequate for a project like this? $250, or $2500?

I see the consumer-level printers all seem to be able to do 8"x8"x8". That would be good enough to print a scale, 26" nosecone in 4 separate pieces that could be epoxied together.
 
I do not have access to a 3d printer... Yet.

What price level of 3D printer would be adequate for a project like this? $250, or $2500?

I see the consumer-level printers all seem to be able to do 8"x8"x8". That would be good enough to print a scale, 26" nosecone in 4 separate pieces that could be epoxied together.
There is a thread on here all about 3D printers. I am just lucky enough to know people with them so I do not have to own one myself.
 
The big challenge I see is getting an upscale version of that lovely ellipsoid nosecone.
I've wondered how close it would be if you took a normal ogive nosecone and rounded the end.
I built a Sprint clone upscaled to BT-55 size with the intent of borrowing the nose cone from my Goblin for it.
 
I've wondered how close it would be if you took a normal ogive nosecone and rounded the end.
I built a Sprint clone upscaled to BT-55 size with the intent of borrowing the nose cone from my Goblin for it.
Thought about that. But I think the fineness (aspect) ratios of the commercially available ogives are too low to get a good result. The ogive profile is really just two circle arcs intersecting. To be able to get the profile I want, I'd have to start with a really high aspect ratio NC.
 
The word "boat" is short for, 'BOut Another Thousand.

Does that sentiment apply to 3D printers, too?
Nothing is better than owning a boat! I still smile, just thinking about mashing the throttle. Blown 468 BBC, 8-71 Supercharger, two speed Powerglide, 90 mph with four people, and a cooler of adult beverages! Bring on the summer.
 

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Nothing is better than owning a boat! I still smile, just thinking about mashing the throttle. Blown 468 BBC, 8-71 Supercharger, two speed Powerglide, 90 mph with four people, and a cooler of adult beverages! Bring on the summer.

With Open Headers pointed to the sky would not four adults need ear plugs PLUS Ear Muffs to not go deaf ?

I've been around them at the Drag Tracks and would not go near them without both. But I already have Tinnitus from my younger days when I didn't think like that.
 
With Open Headers pointed to the sky would not four adults need ear plugs PLUS Ear Muffs to not go deaf ?

I've been around them at the Drag Tracks and would not go near them without both. But I already have Tinnitus from my younger days when I didn't think like that.
I have baffles in the boat's exhaust; It's not bad; the supercharger whin is way louder than the exhaust. I also crew on an A/Fuel car that tends to be much louder.
 

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