Estes Spirit interesting flight...

[caheaton]

In honor of the holiday, I launched the Estes Spirit from the neighborhood park yesterday. First launch was with a B4-4, which I knew would be a low flight but is on the list of approved engines for this rocket. Upon launch, the rocket rose slowly and looked like it was literally struggling to get into the air. After apogee and what I'm guessing was 60 feet, it arced over and ejected the chute at perhaps 20 feet. Safe flight that grew a laugh from a couple of spectators and myself...had to admit it looked rather cool. BUT, according to openrocket it should have climbed to about 100' or so. Winds were light and the only mod to the rocket is the addition of some kevlar cord at the base of the shock cord.

Next launch was with a B6-4. It was a better, more classic flight to about 80 ~ 100'. Perhaps the B4 engine was defective in some way? It was an old motor (didn't check the date code, but over 20 years I'm sure....the B6 motor is only a couple years old). If it was the motor, I've never seen a failure where it just had weak thrust....usually it's a cato or nozzle blow out.

 

[neil_w]

1) I'm confused why 100' would be the expected altitude for that rocket. I just threw the numbers into thruscurve.org and it estimated about 175' - 225' on a B. 100' for a 3.1 oz rocket makes no sense to me.

2) I have had one instance of a "dud" motor. I flew Diamond Cutter on a D12, expecting something like 600'... and got maybe 50'. At first I thought it stuck on the rod, or something... but then I realized that even after it cleared the rod, it still barely moved. Since subsequent flights were normal as expected, I concluded that it simply was a bad motor.

 

[caheaton]

You're correct. I just ran openrocket again and get about 250'. It 'tis strange why this one flies so low....I'll have to fly it some more and see how it shakes out. Previously, it's first (and only until yesterday) had been with a C6 motor. That flight was exactly as expected....lost sight of it on way up until ejection.

 

[Jeff Curtis]

I had a similar experience with a B4-4 at NARAM 61.

 

[BABAR]

Sticky launch rod?

 

[caheaton]

I wondered that too, but other rockets flown (Alpha 3 with A8 and Fat Jax with A3) were fine and just as expected and calculated....very odd.... On the other hand, if it's consistently flies that way with the B4 it will be entertaining.

 

[SharkWhisperer]

I wondered that too, but other rockets flown (Alpha 3 with A8 and Fat Jax with A3) were fine and just as expected and calculated....very odd.... On the other hand, if it's consistently flies that way with the B4 it will be entertaining.

There's sufficient variation in motor delays that your next flight on a B4-4 might pop the chute at 0 feet AGL. You might be better off testing a B4-2?

 

[BABAR]

Sticky launch rod?

Sticky LAUNCH LUG?

maybe paint inside it, or if more than one lug misalignment!

 

[Back_at_it]

My guess is that it stuck on the rod. The Spirit comes with that one piece molded lug with the two holds in it. More than once I've see excess glue in the holes. I've also had at least one that was crushed and didn't fit the rod. Typically I replace them before flight with standard 1/8 lugs about 4" long.

I'd suggest using a hobby knife or 1/8" drill and cleaning those lugs out. I've flown my Spirit on a B6-4 many times with great success. Also wipe down the rod with some steel wool or a scotch bright pad. There might be just enough crud to effect this rocket but not effect rocks with the larger standard lugs.

 

[caheaton]

Just an update. Finally got a chance to fly the Spirit again tonight a couple times. First flight was with an old MRC B4-4. Flight was okay, maybe 150' ? (Just a guess, not good at judging altitude from nearly beneath the rocket). Much better than the first B4-4 launch that struggled...this one was no speed demon but was exactly as expected (except for the 4 second delay that was more like 6 seconds....chute ejected after rocket landed nose first into thankfully very soft ground...no damage at all to rocket).

Next flight was with a new B6-4. (Estes). Flight was flawless with maybe 200' in altitude and ejection just after apogee. So, it seems the culprit was the engine in that first flight. I also double checked the lug on the launch rod...no binding at all. Rocket is fun to fly, but I think I like it better on C engines .

(I also gave my Savage its maiden flights....that one is a load of fun with a C11-0 / A8-5 pair. Perfect stager for small fields.)

 

[Blast it Tom!]

Not the same rocket, but I'm a small field guy as well, yet I find rockets like the Estes Venus Probe and Mercury-Redstone to be somewhat underpowered on the recommended C6-3 motors. The Quest 18mm D16-4's do just enough better to make it a nice flight. So maybe, in addition to a bum motor, sometimes these kits need more oomph! than called for.

(I like your avatar!)

 

[dpower]

A typical MRC B4-4 has lower total impulse than an Estes B4-4 - maybe the nozzle had bits missing?

I like to fly my Spirit on a C6-5 - makes a nice flight, and it didn't cost enough $ or time to worry about losing it.