Eyelash was flown three times on July 17 at the OROC Summer Skies launch. We had a gorgeous low wind day, perfect for main at apogee.
The first flight went to 14551'. It had a little kick into the wind coming out of the tower and landed, 401.5 seconds later about 900 feet from the pad.
I was a little disappointed because simulations had my expectations closer to 16k'.
Inspection of the tailcone, left one, showed that it had been mostly burnt away leaving only about 1/4". JB Weld didn't hold up. Maybe firebrick or metal next time. If 1/4" of tailcone is all that survives, I decided to trim off the rest. There is no point in sending it up if it burns off, consuming energy and adding friction at the same time.
The possibility of reducing the tailcone at the launch was a planned contingency. Calculations of the center of pressure with and without the tailcone were made prior to the launch. Because the tailcone will shift the Cp, both Cp marks were on the rocket to ensure safety in either configuration.
Flight #2 did better: 15220 feet with 431.6 seconds in the air. It came down about 2.4 miles away. Thank you GPS.
For flight #3 I made two changes:
I decided that there might be more drag on the rocket than was used in simulation, so I opened up RASAero II and degraded the paint finish until simulated results roughly matched the flight. Then I predicted the optimal mass and discovered that an extra 50 grams of mass would probably help counteract the extra friction. I tied about 56 grams of tungsten onto the ebay tab with kevlar.
On the tailcone I not only trimmed it, but I ripped out the styrofoam and the remaining short JB weld tube. These burned up on flight #2. All that remained was the ~1/4" long outer shell. It more or less survived flight #3. It's not clear that such a short tailcone adds benefit.
Flight #3 went to 15515 feet and stayed up 402.2 seconds, landing a little over a mile away. The maximum speed was between Mach 1.5 and 1.6. The peak acceleration was about 25 gs. The statistics below incorrectly list it at double that value due to a fleeting noise spike at takeoff.
Eyelash had a pretty good day for altitude and flight time: 45286' and 1235 seconds aloft, nearly 21 minutes.
I have an application pending for the Tripoli I class record.
I think that Eyelash may go higher if the fins are trimmed a little. The rocket was actually over stable at launch.
So that's how I made Eyelash: an altitude seeking minimum diameter I class scratch build.