| Grain # | Tube Length | Recess Length | Propellant Length | Gross Weight | Tube Weight | Propellant Weight | Density |
| 1 | 4.55/4.55 | .14 | 4.41 | 1.6239 | .06825 | 1.55565 | 0.06083 |
| 2 | 4.99/9.54 | .15 | 4.84 | 1.81 | .07485 | 1.73515/ | 0.06182 |
| 3 | 6.04/15.58 | .14 | 5.9 | 2.2141 | .0906 | 2.1235/ | 0.06471 |
| 4 | 5.43/21.01 | .15 | 5.28 | 1.9866 | .08145 | 1.90515/7.31945 | 0.06222 |
| 5 | 5.29/26.3 | .15 | 5.14 | 1.9449 | .07935 | 1.86545/9.1849 | 0.06259 |
| 6 | 5.29/31.59 | .15 | 5.14 | 1.9412 | .07935 | 1.86185/11.04675 | 0.06247 |
| 31.59 | 30.71/5.1183 | 11.5207 | .47385 | 11.04675 | 0.06203 |
Propellant Weight: 11.04675 pounds
Propellant Diameter: 3.0"
Core Diameter: 1.27"
Throat Diameter: .86"
Kn: 331, 367, 343
Assembled Motor Weight: 19.2 pounds
Assembled Rocket Weight: 14.0 pounds
Lift Off Weight: 33.2 pounds
This will be the second launch of the Prelude rocket, this time sporting a new digital video camera. I went through several changes in the plans with the motor for this rocket. I was going to use an APCP load in it, but I was a little short on AP and with new rule making in place I couldn't transport the propellant off my property. So I decided to use KNER propellant again, but then I discovered I had bored out the nozzle throat for use on another 3.5" motor. So I decided to make a new graphite nozzle, and shorten up the propellant stack some. But, I was out of 3.5" graphite... So I went to plan B, or is it C? Anyway, the plan now is to use the bored out nozzle on the original motor, but to add 1% Fe2O3 to speed up the burn rate. Hoping the added iron oxide speeds up the burn to compensate for the low Kn.
Now there is some risk trying this, as I haven't tested KNER with iron oxide extensively. The one good test I have, showed twice the burn rate at normal KNER Kn levels, although not in a motor this size. I still think I'm pretty safe though, as this casing is rated at 3214 psi, even with a normal Kn of 450 the motor shouldn't go much over 1,000 psi.
The propellant casting went well for the motor, density was good at .06203 pounds per cubic inch. The full load of just over 11 pounds will make this a larger propellant load than the Prelude's first flight. But the rocket will have more drag due to the video camera shroud, and several screws to hold the camera mounting bulkhead in place. While casting these grains seems rather mundane and common place compared to the Defiance 5" grains, I need to remind myself this is still an "M" class motor and must be taken seriously.
Flight Electronics:
Translove P6K: 15 second mach delay, main deploy 800'.
Timer: Magnetic switch start, 27 second delay.
Apogee Charge: 7.2 grams
PIRM2 Charge: .65 grams
Expected Apogee: 10,126', Time to apogee 23.6 seconds
Burn Out Weight: 22.15 pounds
Drogue Descent Rate: 60.5 fps
Time Under Drogue: 2:35
Main Descent Rate: 27 fps
Time Under Main: :30
Total Descent Time: 3:05
Launch Day:
This flight actually preceded the Defiance launch (Launch Test 134) so details of setup can be seen on that page. I had forgotten how narrow the clearance was between the Prelude fins and the launch rail. So we spent an extra few minutes making sure the rails were positioned to allow the fins to clear. Once the rail was upright and in position, I turned on the video camera power, then tried to push the video record button to start the recording. For some reason the record indicator light wasn't coming on. The unit was powering up, but after pushing the record button it wasn't indicating it was recording. After several minutes of playing with it, I decided to just make sure the power was on, then push the record button and fly the rocket, even if it wasn't indicating it was recording. The Defiance was waiting to fly and I wasn't going to fuss with this rocket any longer! So after hoping the camera was recording, I sent everyone else back to the spectator line and armed the electronics. The P6K beeped out good continuity, and the timer start magnet was properly positioned to start the timer. I unshorted the igniter leads and hooked up the connections to the ignition cable.
All clear... Joel had the countdown, my mom was at the launch control button.
5,4,3,2,1 and ignition!
Click Here for the video.
The motor lit instantly and the Prelude came off the rail. Right after leaving the rail the Prelude made a turn
to our left, then picked up speed, straightened out somewhat and continued in a nice, straight flight.
Here you can see the Prelude coming off the tower and making a rather disconcerting turn.
Now the rocket picks up some speed and the flight straightens out.
The Prelude now continues in a nice flight to apogee.
We watched as the rocket climbed out of sight. Shortly after a distant thud was heard, the deployment charge smoke was seen, then we sighted the rocket coming down under the drogue chute. We watched the rocket descend under the drogue for almost two minutes, until we lost sight of the rocket to the Southeast of our position. I had the RDF receiver on and tracked it somewhat longer than we did visually until I lost the signal. With the Prelude safely landing, we set about launching the Defiance. I was hoping to recover both rockets at the same time after the two launches. Unfortunately, that wasn't the case. As the Prelude has yet to be located. I've spent considerable time looking for the rocket, made numerous calculations on the probable landing location and still can't find the rocket. At this point I'd have to say either the transmitter quit working, someone picked up the rocket or it landed in a deep ditch that's attenuating the radio signal. I've literally walked and driven into every conceivable location within a 1/4 mile of the possible landing area, and never picked up a beep from the transmitter.
As it turns out the 1% Fe2O3 wasn't enough to make up for the low Kn the enlarged nozzle throat had created. It's quite obvious the rocket didn't have enough thrust off the pad to make it into stable flight. It's a good thing it picked up enough speed when it did, or it could have gone into a cruise missile mode! It looks to me like a Kn of about 390 to 400 would be about right with the 1% iron oxide added.
I'll update this page in the future if the Prelude is located. I've already made several trips to the area and I don't plan any more. I have contacted a number of people in the area, so hopefully if it is found they will contact me.
Update:
The Prelude was recovered almost one year year later! While searching for the Aestus rocket the following fall, Steve M. was stopping by neighbors homes and asking. At one of his stops, the guy says no, haven't seen a blue rocket but I found and red and yellow rocket this past spring. Steve knew right away it was the Prelude. The farmer had it leaned up against a wall in a shed for 7 months. So Steve managed to not only find the Aestus that day, but also the Prelude. The altimeter I used doesn't store flight data once the power is off, so we don't have that. But, both chutes were deployed and the rocket was undamaged, even after sitting out for 5 months in the elements. Even the video camera still worked, but, as I expected, there was no video on the camera since I wasn't able to get it started prior to the flight. The steel nozzle and rest of the motor are fine, it's unlikely I'll ever fly the Prelude again, but it's nice to have it back home anyway.