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Vintage Build: Microsonde III

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Joshua F Thomas

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Two 13/18 adaptators have been built. Because of the couplers between stages and the way they stack I had to build them special for each stage.

Should be able to launch all three stages at the next club launch, assuming I can find some A10T-0 motors.

7B3880D1-1CEE-453A-8820-8F1AC28D2FCC.jpeg
 

BABAR

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Two 13/18 adaptators have been built. Because of the couplers between stages and the way they stack I had to build them special for each stage.

Should be able to launch all three stages at the next club launch, assuming I can find some A10T-0 motors.

View attachment 429768
They look workable. Is the middle section of each adapter necessary? What do they weigh?

Hope you get a great flight!
 

Joshua F Thomas

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The extra length helps with the friction fit that is needed to keep the adapter in place.
 

Joshua F Thomas

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I finallllly got some A10-0Ts. So this is going up on Saturday,, assuming the winds are reasonable. C6-0 -> A10-0T -> A3-4T.

Every possible thing on this rocket is friction fit, which is nerve wracking, but we'll see if my skills are up to the challenge.
 

kuririn

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Just make sure the staging couplers are not too tight, and you'll be fine.
See post #15 in this thread from some guy named John Boren. ;)
Good luck!
 

rklapp

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Don’t see if this was already verified but from the Microsonde font, I’m guessing 1978.
 

kuririn

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Produced from 1970-1978.
Instructions say if you want to order engines directly from MPC, it's 3 for $1.25.
Catalog price for the kit was $3.
Good times.
EDIT: Of course minimum wage was something like $1.60/hr.
:D
 

Joshua F Thomas

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Just make sure the staging couplers are not too tight, and you'll be fine.
See post #15 in this thread from some guy named John Boren. ;)
Good luck!
The couplers are loose enough that I'm using small pieces of tape on the exterior body to hold the stages together until separation.
 

Woody's Workshop

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I have recently acquired a couple more of these kits.
I now have 6 sealed in their original plastic wrap.
If anyone is interested in building one, get in touch with me.
I don't need 6, just ended up being that way.
 

Joshua F Thomas

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And I *still* haven't launched mine - school been so busy lately I haven't had the chance. Perhaps this weekend.
 

Joshua F Thomas

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Ok, so I finally launched this. It was uh, not that great. The first stage went fine (see launch below), but the 2nd and sustainer stages (the 13mm engines) *both* ejected out the back! The first stage separated and recovered fine. The sustainer was found as a lawn dart (see below) with the middle stage still attached. Despite these foul ups, it still managed an apogee of around 500 ft, measured via my FlightSketch.

Some re-engineering is clearly in order. Or I may just hangar queen this thing.

Here's slow-mo video of the launch on the B6-0 lower stage, which went well:


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kuririn

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Tighter fit for your second and third stage motors.
Looser fit for the second to third stage coupler.
Also make sure the transition is not on too tight.
Sand down the shoulder perimeter if needed.
 

BABAR

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Ouch! Hope it’s repairable.

I hope you can get one good three stage flight with a safe recovery before she retires to the hanger!
 

Fishhead

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Produced from 1970-1978.
Instructions say if you want to order engines directly from MPC, it's 3 for $1.25.
Catalog price for the kit was $3.
Good times.
EDIT: Of course minimum wage was something like $1.60/hr.
:D
That's exactly what it was in 1978. I made $1.60/hr + TIPS! Yeah, I found out that waitresses weren't always arithmeticians when it came to calculating 10%.
 

Joshua F Thomas

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I was doing autopsy on the Microsonde when I realized an obvious design flaw and wondered how I missed it before:

127660024_108362697686709_8579190336508929355_n.jpg


The base for the payload pay (where the shock cord attaches) has a hole in it. The ejection charge gases can vent right into the payload bay, and where they can then pop the nosecone off. Remember this is a minimum diameter kit from the 1980s; the nosecone is entirely friction-fit.

So, yeah, that's a problem. It helps explain why the chute never deployed during my previous launch. I decided to fix this issue using some Fix-It epoxy clay, which I was able to jam inside to make a seal, without reducing the space for hooking the shock cord on.

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