Caveman Rocketry Sonic Plop

Caveman Rocketry - Sonic Plop {Kit}

Contributed by Robert Runnalls

Manufacturer: Caveman Rocketry
Rating
( Contributed - by Robert Runnalls - 06/01/02)

PartsBrief:
Your basic 4 fins and a nose cone rocket designed to go SUPERSONIC.

Construction:
The kit contains:

  • 1 - Resin poured conical nose cone 5" visible, 1" shoulder.
  • C/W center embedded eye screw.
  • 1 - 12" extra thick 29mm phenolic body tube.
  • 1 - 29mm aluminium Baffle system
  • 1 - Steel wool for baffle
  • 1 - 32" Kevlar® string for shock cord
  • 1 - Eye screw baffle shock cord attachment
  • 1 - Heavy duty nylon parachute
  • 1 - Engine block
  • 1 - Chopstick for applying glue in hard to reach places
  • 1 - Instruction sheet.

The instructions were translated from Dutch to English and therefore loose some meaning in the translation, but are still understandable. The format used is logical and easy to follow although any person with a little experience could put this rocket together with little to no problem anyway.

In the 2 kits I received there were no slots in the body tube but Caveman Rocketry said that fin slots would be normal. This is not true through-the-wall construction as the fins just long enough to go through the thickness of the body tube and then are equal (flush) to the inside of the tube's wall. The thickness of the body tube is what allows this slot arrangement to work well in this situation. By using CA glue for the initial tack, and epoxy for the fillets, nothing short of stepping on the fins will break them and then it would be the body tube that succumbed to the damage.

The nose cone needed a little sanding for the proper fit, but nothing out of the ordinary. With the chopstick, the baffle and motor block were easy to glue in place.

I personally don't like Kevlar® string and that is what comes with this kit, so any comment of that would be biased.

The kevlar string is attached to the center of the baffle via an eye screw. If you look at the picture of the parts you can see it attached to the string which is attached to the nose cone. The Baffle is aluminum about 1/4 inch thick with 4 holes drilled in it and a center tap for the eye screw.

All in all, this kit went together well and is very sturdy using a combination of CA and epoxy.

Rocket PicFinishing:
This kit does not come with decals but was easy to paint and accepted the paint well. The only recommendation that Caveman Rocketry gives you is to make it highly visible.

Construction Rating: 4 out of 5

Flight:

Flight 1 D12-5 Good flight
est alt 750 ft.
est speed 150 mph
est speed at ejection 17 mph

Flight 2 E9-6 Good flight
est alt 1700 ft
est speed 250 mph
est speed at ejection 43 mph

Flight 3 E15-7 Good flight, Slight zipper
est alt 2300 ft
est speed 310 mph
est speed at ejection 43 mph

Flight 4 E30-7 Good flight, Zippered
est alt 2380
est speed 380 mph
est speed at ejection 60 mph

Flight 5 F20-5 Good flight, Zippered
est alt 3500
est speed 450 mph
est speed at ejection 65 mph

All flights were well within acceptable limits but it was susceptible to wind cocking in winds above 10mph. Motors were held in with masking tape and in the case of the 24mm motors an adapter was used.

Recovery:
Recovery of this rocket is by a heavy duty 12" nylon parachute that does the job well. Although decent is a little faster than normal, because of the altitudes this rocket can reach, it is considered a good match. With either too short or too long of delay times the thin string shock cord can zipper the body tube. So great care must be taken in choosing the delay time.

Flight Rating: 4 out of 5

Summary:
For what this rocket is meant for, FAST AND HIGH, it does it's job well, and even on Aerotech E motors this rocket is a real neck snapper and yet is still quite recoverable.

Overall Rating: 4 out of 5

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