This rocket was inspired by the fins on an Apogee Skonk Wulf which kind of look like shark fins. That lead me to building a hammerhead nose cone.
I used a couple of techniques on this rocket that were new to me: Papering fins and Through The Wall (TTW) fins.
The fins are 1/8" balsa papered using Elmer's White Glue and 61 lb Staples double sided matte paper.
The nose cone I turned on my wood lathe from a pine 4 x 4. The hammer portion is made from a pine 1 x 3. The hammer is a tenon fit into the nose cone affixed using Gorilla Wood Glue. There's quite a nit of surface area for the glue, so it's quite strong.
This rocket needs a lot of nose weight. I ended up using a 3/4" Machine Screw that threads into the bore of the nose cone.
Power is via a composite 29mm motor, another 1st for me. Parachute is 28" rip stop nylon.
Stability calculated using Open Rocket software and verified via a swing test.
Link to build thread: (1) Lakeroadster's "Hammerhead Shark" | The Rocketry Forum
Flight Date: | 2022-06-30 |
Rocket Name: | (BAR-03) Hammerhead Shark |
Flyer's Name: | John Simmons |
Motors: | F42-8 |
Expected Altitude: | 1,051 Feet |
Wind Speed: | 5.00 mph |
Launch Site: | Local |
Actual Altitude: | 1,051 Feet |
Ignition isn't as quick as black powder motors, but there was no chuffing.
Very minimal time lapse between ignition and lift off.
The composite motor was quite impressive. The rocket accelerated quickly, plenty of speed at launch rod exit (38.4 mph per sim)
Winds were less than 5 mph and from the northeast. There was no weathercocking.
The rocket went nearly straight up. Because of this straight up perspective, we were all able to observe that the rear of the rocket fish tailed from about 30 feet up until apogee. The simulation software estimated apogee @ 1,051 feet, and the launch seemed to reflect that (no altimeter was used).
The chute fully deployed. For wading a rolled up crepe paper streamer was used, but it did not deploy?
The rocket ground hit southeast, at an estimated 600 feet from the launch horse, much farther than one would expect?
Photo's were taken of the rocket at it's ground hit location. Upon further review the rocket was undamaged.
The crepe paper streamer "puck" was still in the rocket and stopped at a knot in the Kevlar shock chord.
The motor was no longer in the rocket.
Chute was undamaged and had one small area of soot from the ejecting charge.
What was learned from this flight?
The home made motor clip hook end should have had tape wrapped or wired around the motor to ensure it didn't become disengaged from the motor at ejection. Evidently "The God's Of Recovery" were on hand to ensure the parachute deployed before the motor was spit out.
Try to get a video of the rocket as it flies upward, to capture the fish tailing. I am told this is known as "coning". But from what I have read, coning occurs due to the rocket spinning. It didn't appear to be spinning.
The chute appeared to be too big due to the distance that the rocket drifted... but keep in mind the motor was kicked out at ejection. Therefore, the rocket was significantly lighter. Next time ensure there are no knots in the Kevlar that can prevent the crepe paper streamer puck from smoothly ejecting the body tube.
Also, make the puck smaller than the inside diameter of the rocket. Then use some crepe paper to form an X-Pattern across the puck and up the sides of the puck to close any gaps around the puck.
Stage | Motor(s) |
---|---|
1 | Aerotech F42T-8 |
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