I wasn't able to attend Saturday's launch. The day was busy finishing up with a night launch.
Here's some highlight's of the Sunday activities.
Gary (the Dolphin) Dahlke flew the two stage DIRTY HARRY'S MAGNUM FORCE with a K454 in the booster and an I180 in the sustainer.
When Gary flys these big two stagers, all activity stops with everyone focused on the flight. Both sections landed close to the pads.
Here's my FRANKEN GOBLIN with a C6-5.
Stable, reliable and recovery under a garbage bag parachute with a big spill hole.
Carl Campbell flew two Delta Heavys and the Sherry's Hot Rockets MERCURY REDSTONE with a G71 white Lightning.
Two parachutes brought it back without damage.
After 42 years of launches, here's my first three engine cluster!The Semroc DEFENDER was fast off the pad with a trio of B6-6 engines. Two were newer Estes B6-6s and the third was a 35 year old Centuri B6-6. All performed up to specs using Quest Q2G2 igniters.
I would guess the altitude was 1,000 feet, the delays were longer than the recommended B6-4s.
Check out the charring between the engines after flight.
Roger Smith (jonrocket.com, rocketreviews.com) flew the upscaled Odd'l Rocket Breakaway - the U-BEE with a K550 White Lighting.Boost was slow and beautiful. Apogee was 1,528 feet.
At ejection, one tethered section separated. The upper section came down on parachute, the lower sections (still tied together) tumbled in.
There was no damage, just a loose fin.
My Centuri FINLESS was again unstable with an Estes B6-4.After the unstable C6-5 flight at last months NEFAR launch, I was determined to see it fly stable again using a lighter engine.
No so, it did a little skywriting and will be retired.
It has flown stable with a B6-4 before.
Below the nose there is .40 oz. of clay. It'll fly well with an A8-3, but not high enough to justify wasting engines.
Too bad, I like the design. No wonder it was never produced as a kit.
Also flown:
The new Odd'l Rockets kit, the CORKSCREW with an A3-4t. It lived up to it's name, spiraling to an estimated 500' altitude. Streamer recovery.
PIGASUS again proved the adage, "When pig's fly!" Stable with an Estes C6-5 to 750'. Parachute recovery and no damage on landing.
For future ref it sure would be nice to no where the finless is stable. If you added another 1/4 oz of nose weight would it move the CG appreciablely?
ReplyDeleteI smiled when I read this blog. I've been flying since 1967, and have never had a successful cluster flight, so congrats on that Defender launch! Two Sunday's ago, I attempted to launch an Estes Metalizer, that I modified to use a 4 A-10-T cluster. I used the same Q2G2 igniters. rs you did, but only two motors lit, and the model got hung up on the launch rod. Oh well.guess we'll have to wait for spring in RI to work the kinks out. As always. your blog is enjoyable reading.
ReplyDeleteHi Jeff,
ReplyDeleteI wish the original plans had the CG position shown, but back then no published plans from Estes or Centuri did! Swing testing never really worked for me.
Centuri only recommended the A8-3, A5-2 and B4-2. The B4-2 is just a little lighter than the B6-4. I had two stable B6-4 flights before the unstable flight on Saturday. The C6-5 wasn't good!
It surprises me, I've flown the Hot Rod Rockets Bell Bottom (pretty much a downscale of the Centuri Finless) and it's stable with all "T" engines.
If I added more weight (in addtion to the .40 oz. of clay already in the nose) it would probably cancel out any extra altitude gained with a bigger engine.
Oh well, live and learn!
Hi RIJoe,
ReplyDeleteThanks, I'm glad you enjoy the blog.
I was really nervous about this 3 engine cluster. It probably goes back to when I tried to launch an Estes Gemini Titan with two engines. Only one lit and the off center thrust drove it into the dirt.
Nowadays, the Quest Q2G2 igniters are still the best way to go.
Hard to believe anybody was able to get a four engine ignition using bare nichrome on a Estes Saturn 1B in the late 1960s!
(You've been doing this two years longer than me and would understand the last sentence.)
I guess I was just curious if another 1/4 oz moved the CG appreciably. I wish I was close by. I'd be willing to test until its stable. Not for the C6 but to ensure the B6 is stable. It must be very close.
ReplyDeleteBest wishe
Jeff
Hi Jeff, I would think the B6-4 would be stable everytime, two out of three B6-4 flights were stable. The one C6-5 flight was unstable. Looking at the Estes catalog, A B4-2 weighs .70 oz. A B6-4 weighs .71 oz. The B4-2 was a recommended engine for this rocket, from the Centuri plan sheet. They're both so close in weight, it shouldn't matter!
ReplyDeleteOne thing to know about flare stabilized rockets, it is all about the angle of the flare. The Bell Bottom design has more flare angle, which gives it more stability. If you shortened the flare length on your Centuri Finless by about an inch, I think it would work much better.
ReplyDeleteHi Eero,
DeleteThat might be true!
Also the extra weight of the C engine might have pushed it over the stability "edge".