It was time to stop playing around with those little motors and sent the Vector up on a composite D-motor. Because of the expected altitude of this rocket, in addition to the altimeter / accelerometer in the top payload, I installed an audible beeper in the lower payload section to be able to find this model in the tall grass. The additional 14 gram weight shouldn't affect the flight too much, since it already has 7 grams of altimeter and 22 grams of additional nose weight.

The engine chugged three or four times before a solid ignition, and then the rocket tore off the pad with a longer flame and denser smoke than any Estes black-powder engine I've ever used. It accelerated at a peak of 12 Gs, and averaged 5.4 Gs for the 1.4 second burn time. That acceleration was twice what I could expect from a B6 or C6 motor, but it is achieved at 3-times the cost. With that acceleration in light winds I expected very little weather-cocking, but this model turned and flew upwards at about a 30-degree angle from straight.

It reached a speed of 168 mph, and coasted for 5.2 seconds before reaching an apogee of 742 feet. Ejection was late at 7.9 seconds, allowing the model to descend for 2.7 seconds to an altitude one hundred feet lower (641 feet). During this coast time it traveled very far upwind. The parachute ejected and it descended at 19 mph - a bit fast but safe enough (normally).

Considering the distance it traveled upwind, it was good that it came down fast or it easily could have been lost. After a flight time of 32.2 seconds, it landed hard in the dirt of a baseball diamond instead of the typical grass field. This caused a minor separation crack in one fin where the two balsa pieces were glued together to form one fin. As a test flight, this proved that the new ejection baffle and Kevlar shock cord are strong enough for the D10 motor.

Inspection of the heavy-duty nylon parachute revealed the cause of the abnormally high descent rate. The shrouds were formed in the usual way: double the length from the chute to the attachment point and back to the parachute. At the attachment point, I used a small loop of Kevlar so that the smaller Kevlar thread would fit into the small wire loop of a fishing swivel.

Since I didn't think to glue the individual shroud lines to the Kevlar loop, one shroud loop pulled through about 2 or three inches, making the opposite shroud line too short. With one shroud too short and another too long, the parachute opened lopsided. Lesson learned: Glue the shroud lines together to prevent slipping.