Time for a build thread! (Adapted from social media posts; a lot of you know the history stuff.)

The Microsonde 3 was produced by Model Products Corporation (then a subsidiary of General Mills, which wanted to branch out from cereals to toys) from around 1969 - 1972.


GM/MPC made models, motors, parts, and launch gear. The designs and expertise came from Mike Bergenske; whose model rocket company MRI was purchased by MPC. Bill Stine was also brought in; he designed many of the kits, including the Flat Cat glider.

An early version of the Microsonde was listed in the MRI catalog; it didn't have the plastic payload section. So, this is Bergenske's design.

The rockets were made for the mass market and MANY were made.

They ended up losing money on their attempt to get into model rocketry. Rocket motors were still not legal in many states. Retailers who'd stocked kits that couldn't be flown were not happy!

The box refers to some vaporware . . . the C9-0 engine, made in small quantities but never put into production. It would have been perfect for the first stage of this model! I plan on using some left-over C5-0 and B8-0 motors.

MPC didn't produce a lot varieties of motor; the A3-2 was recommended for the third stage. The delay was far too short for that purpose. Well, we have A8-5 motors now. Great for that application.

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NAR #27085 - Oregon Rocketry - SAM

MPC kit parts were fairly high quality. Some models had plastic fins, others you cut from a printed balsa sheet.

The Microsonde 3 is a three-stager, so three sets of fins and three body tubes.

The shoulder of the plastic transition section is far too short. I'm thinking of solutions.

I'm going to use a much longer piece of fresh elastic for the shock cord, and add a barrel swivel.

Also adding a second launch lug (on the first stage).

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NAR #27085 - Oregon Rocketry - SAM

The kit as designed had the motor mount tubes projecting rearward from each stage. I'm going for the Estes method of taping the motors together, and adding a rear centering ring to the booster.

I made a longer 1st stage motor mount & shifted things forward, the motor mounts project forward from the boosters. This moves the mass of the three motors forward, meaning slightly better stability.

Taped-together motors are for test fitting.

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NAR #27085 - Oregon Rocketry - SAM

I've got this one ready to paint or fly, whichever comes first. Same with the Semroc Cyber III.

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Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Centuri Design Contest F-150 Hurricane Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark, Groonie Der V 1/2

I bought and built my first MPC kit in late 1970. Large blocks of the instructions were copied from kit to kit, so the layout and art on the instruction sheet are so familiar! The instruction sheet has pretty good advice, but approaching them as a technical writer, I see gaps. Such as, it doesn't mention sealing the fins (but does recommend sealing the cardboard tubes).

The Countdown Card has the safety code on the back.

A "research report" going into more details on mounting motors in a multi-stage kit was included. Putting tape on the outside of the boosters is a strange technique that I can see leading to trouble.

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NAR #27085 - Oregon Rocketry - SAM

Starting the build!

First photo shows 1st and 3rd stage motor mounts, with engine blocks in place.

I cut a piece of BT-20 for the longer first stage motor mount tube. It is a bit larger than the MPC motor mount tube, but not problematically so.

The 1st stage mount has a rear ring to prevent the booster motor from getting knocked out leaving the stage stuck on the 2nd stage, with its thrust burning out the 2st stage. That has happened with many of my multi-stage flights!

I finished yesterday's build session by cutting out and shaping and smoothing the fins.

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NAR #27085 - Oregon Rocketry - SAM

A minor correction. It was G. Harry Stine (Bill's Father) who worked on kit design with MPC.

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Bob
S.A.M. # 0014

Argh, 100% correct. Just a brain fart.

The local (Glen Cove, NY) hobby shop that carried MPC (and Cox!) items had a copy of Stine's "Model Rocketry Manual," which was a cut-down version of "The Handbook of Model Rocketry." Many of the same illustrations, for example. That edition -- black cover-- was very MPC-centric, in that it had photos of MPC rockets, mentioned the kit names in the text, and used MPC motors in thrust curve comparisons.

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NAR #27085 - Oregon Rocketry - SAM

My local library had the Model Rocketry Manual along with a 3rd edition of Stine's Handbook. You are quite correct about the focus on MPC products.

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Bob
S.A.M. # 0014

I did this Microsonde 3 a few years ago. I remade the fins in basswood. It took a lot of cutting but it was worth the effort and the blood loss.

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Never trust an atom. They make up everything.

4 out of 3 people struggle with math.

Chemically, alcohol IS a solution.

NAR# 94042
SAM# 0078