My estimated dimensions (so far) are as follows:

Overall length ~36-2/3 inches
Main airframe length ~25 inches
Main airframe diameter ~ 1.9–2.1 inches
Nose cone length ~ 5.1-5.2 inches
Nose cone widest dimension ~2.5 inches
Exposed section of motor mount tubing ~3-1/4 inches

The main airframe was a mailing tube. I favor the larger tube dimension for the airframe diameter because I had trouble seeing where the edge of the tube was in the ultra-zoomed in, grainy photo of Harry with his rocket. The photo of the Honest Ivan being prepped for launch had some better contrast between the sky and the rocket and from that I estimated the larger diameter. In that other thread, Dave Fitch estimated a main airframe diameter of 2.25-inches (2-inch mailing tube). I am inclined to agree with that estimate. The next common size up and down for mailing tubes (even back in 1958) don’t fit. Note that these estimates put the diameter into BT-70 territory which George Gassaway (in the other thread) estimated as being close to original.

The motor mount tubes were most likely Model Missile Industries (MMI) tubes, which later became Estes BT-40 tubes. There were no BT-20, -30, or -50 tubes back in those days. It looks like they were crammed into the aft end of the airframe because the cluster didn’t quite fit. You can see in closeups how the end of the airframe was slit and flared, and that motor mount tubing projects beyond the outer diameter of the main airframe. Either that, or we are looking at damage from that power-prang. Dave Fitch described the motor cluster to be constructed similarly to the Semroc Hydra 7 (another 7-motor cluster). That seems about right to me. Or... it's just damaged from the second flight.

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-Wolfram v. Kiparski
NAR 28643 - TRA 15520
MTMA Section #606 President