Sunday, September 23, 2007

Launch Log 2007.09.22

We had 7 launches on this awesome late-summer afternoon. We pulled out the Renegade which hasn't flown in a while, melted the Stingray, and broke the fin on the Purple Rhino - again. Spencer wanted to fly the Firestreak SST but it has a broken fin from little boys playing with rockets so we'll have to wait for a replacement part.

  • Firehawk | 1/2 A3 | straight flight, higher than usual on 1/2 A3, drifted in recovery to land 100 yards from pad

  • Renegade | C6 | Isaac did most of the prep, some weather cocking, drifted in recovery to land 120 yards from pad

  • Army Man | B6 | impressive flight on a B6; no weather cocking but drifted a lot in recovery; landed about 200 yards from pad - bounced in a parking lot

  • Stingray | 1/2 A3 | Spencer thought about prep'ing the rocket, weather cocked just enough to land close to pad on streamer recovery

  • Purple Rhino | 4 x A10 | beautiful flight - love this rocket; no weather cocking; light wind so landed pretty close to pad

  • Firehawk | 1/2 A3 | neighborhood kid joined us and did the prep; chute got stuff in ejection so motor ejected; no damage to rocket (other than lost motor retainer

  • Stingray | 1/2 A3 | the ejection charge blew the nose-cone off the rocket and melted / deformed the top 60% of the fuselage; fuselage and nose-cone both recovered but rocket is damaged beyond repair because of the deforming of the fuselage

Before the final Stingray flight, we attempted to launch Mighty Mouse 2. I didn't have anything to use for flash-in-the-pan ignition, so we tried using solar igniters. After 3 attempts of getting rocket to pad, count-down, fail, check connection and for shorts, we gave up. We're thinking we need to build or buy a bigger launcher (one that uses a bigger battery anyway).

Spencer can't hold down the launch key, so Isaac holds the key and Spencer pushes the button.

Team work - and the rocket lifts off. Note that it is the person pushing the launch button that does the count-down.

Spencer finishes off his launch by doing his own retrieval. Well done, Spencer.

Bullet Ground-Testing

I've been reading a lot lately that you need to always ground-test to make sure that the charge can separate the loaded rocket. I had actually planned to fly the Bullet without ground-testing but I'm ready to fly the Bullet and the next available date isn't until November so ground-testing sounded kinda fun.

I prep'd the rocket (without an engine) and fed the wire for the Main ejection canister through the static port hole. Some people, so I'm told, do their ground-testing using a tube taped to the static port hole and they suck on the tube and then when they release, the AV bay represurrized and the computer fires the charges. I manually tested the computer separately a few days ago using it's built-
in test sequences and am just testing the separation in my ground-testing here.

Isaac thought that the test failed; he knew that the rocket wasn't going to launch but he thought that the chute was supposed to open. I used the canisters that I built a couple weeks ago and calculated that I needed about 2.5 g of FFFFg black powder for the ejection charge. A failure would have either been the whole upper section shredding from too big a charge or the nose code not popping out with force from too small a charge. Looks to me like the 2.5 g was just right.

Launch Log 2007.09.20

We met up with some friends at the park at 6p to play and launch some rockets. We had 5 launches and ended the evening by losing Mighty Mouse - yes, the original. Very sad.

By the time we all ate, it was after 6:30p - that means the sun was about to go down. The field had been in use by a bunch of soccer teams, so we weren't just waiting to finish eating. We performed a rapid setup and prep on the Firestreak SST and launched it for a nearly perfect flight on a 1/2 A3.

The second flight was the Firehawk on an A3, but we had intended to use a 1/2 A3. With dusking coming and a bit of a break, we needed to keep landings close to the pad and that meant lower flights. The Firehawk is a great flyer and it went out of sight on the A3. There was almost no weather cocking so a long walk crossed my mind; fortunately, the chute only opened about 70% so decent was quick but not destructive.

Third flight was the Firestreak SST again but this time with Sam pushing the button. Another great flight on a 1/2 A3 - Spencer loves his rocket and set it asside with the intention of us launching it again right after launching the Stingray. The Stingray was unexciting on a 1/2 A3 - just too small to see in the near dusk conditions.

The Firestreak SST wasn't ready for a flight yet, so I loaded up Mighty Mouse for a flight on a C6. What was I thinking? Bad choice - so long Mighty Mouse. After spending some time looking for Mighty Mouse, we cleaned up and went home.

Sunday, September 16, 2007

Recovery Canisters

When I built the Bullet, I went with a common canister for storing the recovery charges: a PVC cap attached to the AV bay. Now that I've watched many people prep for flights, I've decided to switch to these Polyethylene tubing-based canisters. I'm hoping to do ground tests tomorrow for separation for main chute deployment so I made some canisters today.

In the pictures above, you can see the first couple steps I use. Since the glue takes a moment to set and the ROL article is light on details on technique, I decided to record my steps for future reference. I found it easiest to put a partial ring of glue around the bottom before involving the e-match. There would be just a little gap open to get the e-match in. After the partial ring set, I put the e-match in and put just a small drop of glue in to hold the match and then let that set. Finally, I'd put in the final bit of glue and fill it out at the bottom.

The reason for the multiple steps was that putting too much glue in at once made it too difficult to manage the e-match. For the separation tests tomorrow, I'll need to add 3g of black powder to the canister and cap it with masking tape but the hard part is done now.

Monday, September 10, 2007

Launch Log 2007.09.09

Mom and I briefly attended the Tripoli Colorado commercial launch on Saturday (2007.09.08) but we didn't launch anything. We got to see an impressive flight on a SkyRipper K motor - that was the first flight I'd seen on a hybrid (other than a couple Alpha Hybrid test flights that blew up the rockets). I attended the Tripoli Colorado research launch on Sunday (2007.09.09) for about 5 hours and got to see some static tests, more Alpha Hybrid tests (yes, again, they destroyed the rocket), and some big launches on home-built motors.

When we got home from our trip in the mountains, we all went over to the field by our house and launched a few rockets of our own. The first flight was Spencers new purple rocket: the Firestreak SST. The Firestreak SST was purchased to replace Spencer's previous favorite: the 'silver nose' Outlaw which finally broke a fin and is no longer flyable. The Firestreak SST used a A3-4T for its first flight and flew great but recovery was not ideal: it uses a streamer for recovery but the streamer didn't appear to slow the rocket much.

Our second flight was Isaac's new Firehawk. Isaac built and put the decals on the Firehawk himself but I assisted with the glueing. Isaac even tied the shock cord on. We flew the Firehawk on an A3-4T but recovery here was also a bit of a problem: chute didn't open right and got tangled up. We'll have to watch it closely on the next flight - perhaps we didn't pack the chute good enough on this first flight.

Isaac preparing Firehawk for first flight.Isaac posing with Firehawk ready for flight.

It was a bit windy: we had to tilt the launch rod quite a bit to keep the rockets coming down within walking distance.

We flew Mighty Mouse on a B4-2 and Army Man also on a B4-2. Might Mouse landed in a pine tree but was recovered and had no damage. Great straight flight and drifted a bit in recovery. Army Man landed behind the school; Shanelle was hoping it was on the school but the boys recovered it without trouble. It flew great on the B4 with very little weather cocking (which is why it landed so far away :) ).

Sunday, September 02, 2007

Launch Log 2007.09.01

We launched at the NCR North Site which is in the Pawnee Grasslands. The launch ceiling was around 20,000 or 25,000 feet but none of our rockets were sent to even 1/10th that altitude today. We launched the Purple Rhino, Migthy Mouse, Army Man, and then Mighty Mouse 2.
Mighty Mouse 2 sitting the pad waiting for launch.Mighty Mouse 2 lifting off the pad.

Our first flight was a flash-in-the-pan ignition of the Rhino. It flew 4 A10-3T's which carried it high and straight even though only 3 of the 4 motors lit. The second flight was the Mighty Mouse on a C6-7. The 7 second delay was nice because that kept the Mighty Mouse pretty close to the pad even though it was a nice, high boost. The third flight was Army Man with the split set for the center of the rocket. Past flights of Army Man suggested that it was heavy or not aerodynamic so we used a C6-3; I'm pretty sure it hadn't hit apogee when the chute opened. We had to walk quite a ways to recover Army Man but we did find it. Finally, we launched Might Mouse 2 for the first time. We used 3 A3-4T's with a flash in the pan (but the pan in this case was a Cherry Coke can rather than our usual ceramic dish). I was worried that the flash wouldn't light all motors because the can wasn't as close as I usually like but all motors did light and it was high and straight.

We saw a couple dozen other flights. There were quite a few problems - more than I've seen at a public launch. One rocket got tangled on the rod, caught fire, and then knocked the launch pad over. Two rockets went unstable immediately and landed in the viewing area. Quite a few recovery failures; this one in particular was interesting:
The pin / ball rocket on the pad preparing for launch.Beautify flame on the pin / ball rocket.Quite a crowd went out to examine the remains and mourn for the pin / ball.

This bowling pin and ball was pretty and flew nicely, but recovery failed completely. It went ballistic and fortunately landed quite a ways away from the launch line because was a big, fast impact.