V2 for my L3

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I know this is a touchy subject that is probably the most contentious among the community, but I don't want this thread to be another airing of grievances.

I agree that there needs to be a broadly clarified point, but in the end, regardless of what the letter of the rules may say, I got lucky. Because.my suspicion is that I had not properly sealed.my electronics bay, and that multiple main charges went off at once...I elongated multiple swivels...that was bad, and l'm luck the NC didn't come free with the main, and dropped the fin can, motor, and bdy tube on a 36" chute. Bad times, and definitely my bad. I will not be able to.confirm this until I pull the data from the altimeters when I get home.

I actually thing I deserved to fail because the rocket spun like a top because of the Mobius shroud. My gut said leave it off, but I wanted the video, and ignored my best prudence. Had it spun much faster it would have surely failed.

Regardless of if you agree with me or not, please don't debate the decision here. I'm trying to lay out the whole story of my L3 project...good, bad, spinning, failing, and to be analyzing, remediating, and succeeding.
 
I do appreciate the support offered though. If it had granted a pass I would have taken it...I ain't proud. In the end I do this as a hobby for the same reason I told my wife 5 years ago "because no one is counting on the outcome." It's fun, and not something I'm going to worry about, because then it won't be fun.

Also,my messages are full of typos because I've been using my phone only since arriving for Airfest...thumbs too fat to type.
 
Cl(VII) said:
Regardless of if you agree with me or not, please don't debate the decision here. I'm trying to lay out the whole story of my L3 project...good, bad, spinning, failing, and to be analyzing, remediating, and succeeding.
Click to expand...

This totally wasn't my intent when I asked the question. Pure curiosity. I hope that discourse from others stays civil.
 
I for one have no ill will, and the question is legit, and contentiously debated...I just don't want the debate on my carefully cultivated lawn (this thread, my real lawn is a mess).

Also, no one need feel they should go back and edit their comments, I'm just trying to avoid the further decent on this topic.
 
CI(VII): I, for one, sir, applaud your civility... :)
 
Back to the rocket :eek:

So the Mobius shroud/camera caused a spin about the Rocket's axis? I find that very interesting. If anything, I'd have predicted that it would impart a slight deviation to the Rocket's course.

Where was it placed?
 
Now you can justify another M motor and a trip to a high waiver launch to your wife. This isn't failure; it's a win!
 
Nytrunner said:
Back to the rocket :eek:

So the Mobius shroud/camera caused a spin about the Rocket's axis? I find that very interesting. If anything, I'd have predicted that it would impart a slight deviation to the Rocket's course.

Where was it placed?
Click to expand...

Yea I was thinking the same thing. I have a 4" V2 and it spins like crazy from the time it leaves and I don't have a camera mounted.
 
Your rocket is a great build and the M650 was fun to watch. The down part was not what you planned and I could tell by your reaction that at the end of the day you would've wanted your L3 flight to go as planned.

Nice to meet you at see the V2 in person. You will get it all figured out.
 
Nytrunner said:
Back to the rocket :eek:

So the Mobius shroud/camera caused a spin about the Rocket's axis? I find that very interesting. If anything, I'd have predicted that it would impart a slight deviation to the Rocket's course.

Where was it placed?
Click to expand...

I have flown my Mobius cameras using the 3D shroud on a half dozen rockets on dozens of flights and have not experienced what I would consider to be excessive spin induced by the camera. I do have an Intimidator 3 that I flew yesterday with the shrouded camera attached, and it did not have any more spin than when I flew it using a fully recessed lens pointed through a large hole in the switchband.
 
Best guess on the spin is the camera shroud. I was 1.05 call stable and the shroud was smack on the CP. I think I put it in the exact wrong spot. The really long burn gave it lots of time to spin up too.
 
Cl(VII) said:
Best guess on the spin is the camera shroud. I was 1.05 call stable and the shroud was smack on the CP. I think I put it in the exact wrong spot. The really long burn gave it lots of time to spin up too.
Click to expand...

Well, the conundrum is this. Without a camera attached to the rocket you will not know whether or not the camera induced the spin or not, without mounting the camera internally with the lens pointed through an observation portal. Anyway, the best of luck on your next attempt.
 
dshmel said:
Well, the conundrum is this. Without a camera attached to the rocket you will not know whether or not the camera induced the spin or not, without mounting the camera internally with the lens pointed through an observation portal. Anyway, the best of luck on your next attempt.
Click to expand...

Yep. Just going to leave it off next time, and see how it goes. The smoke trail will tell the spin tale.
 
It wasn't an electronics bay leak. The alts fired exactly when they should have. It must have been the spinning. DOH!
 
Chris,

My Madcow Black Brandt II also had a Mobius camera shroud and did 7 rotations on its way up. The rotational speed was definitely proportional to the forward velocity.

The fincan spun like mad on the way down under drogue, but that is a different story. Sky, dirt, sky, dirt, sky, dirt, sky, dirt, sky, dirt, sky, dirt, sky, dirt, sky, dirt, for about a minute and a half until the main came out. The swivel at the top of the fincan got a workout.

David
 
Why would a camera shroud cause the rocket to spin? Drag and arcing, sure, but it would have to generate a local side force (which out at a distance from centerline creates a moment, i.e. rotational torque) to cause rotation of the rocket. The shroud is symmetrical side-to-side, right? And it is aimed straight aft? If yes to both it should cause spin of any kind.

I would look close at your fins for the source of the rotation. Either the bevels are asymmetric, or the fins are mis-aligned.

Though, other than the dizzying video, and maybe some lost altitude, no ill effects. And added stability, like Tonimus said, "It's not a bug, it's a feature."
 
dshmel said:
From the NAR website:

3.6 The actual flight shall meet ALL of the following requirements:

a) The rocket shall use a motor with total impulse greater than 5120 Newton-
seconds b) The flight shall be made while a suitable FAA waiver is in effect

c) The rocket shall make a stable, safe flight. Safety includes compliance with FAA
waiver limits. Models that exceed the FAA waiver altitude are, by definition,
unsafe and cannot be certified.

d) The rocket shall fully deploy its recovery system. An anomalous deployment of
the recovery system is not cause for flight rejection if the model descended in a
safe manner. It is up to the judgement of the Flight Witnesses whether the model
descended in a safe manner.

e) The rocket shall remain intact, with no separation of parts that do not deploy
their own recovery device(s
Click to expand...

Ummmm, So actually NAR could give a pass with a main at apogee. Well, I'd consider it a reasonable design attribute if one planned the rocket could do either scenario but it of course would depend upon the radius of the
waiver. If the waiver radius was 2 miles then technically if the rocket was undamaged and could be flown again it could be passed if it landed at 1.5 miles from the center of the waivered area.

Nonetheless, since it's going to be done again fly it without the camera. That will prove if that was the only factor involved 'cause if you see no spin, it's that derned Mobius shroud. Other things could be subtle fin geometry difference, nozzle or grain asymmetry to name a few.

Spinning on descent? Cripes people have conventional rockets that spin like crazy on the harness during drogue descent. I had a rocket where "everything" was right and it glided tail first under drogue in very wide circles. It would descend in a circle, climb a bit, stall out and descend some more. Since the the rocket could be horizontal when the main blew, it would come out horizontally and the tail would swing lazily down like a pendulum. Darnedest thing to see and no way in Hades could I
"plan" a rocket to do that. I lost it in a hard landing and tried to clone it but the clone doesn't have this behavior. It was a cardboard rocket and those things do wear down over time. I once blew the side out of "tired old" one at apogee. Made a nice onboard video so I knew exactly how the failure occurred and it wasn't "just" a broken drogue harness.

I don't know why two good altimeters would blow a main at apogee if you planned on a drogue/main profile though. That's weird. I wouldn't think the Rf from a 100Mw EggFinder would dork two altimeters at the same time so that theory is defective.

Now if your chute was tangled pretty badly and your rocket survived a good "hit" because you built it strong, I can see walking away and doing a "do over" if it was me. If it was a good main and safe landing within the waiver I'd say it's good and valid.
I don't think "it's sloppy" as some would say. Again, I'd consider it a reasonable design consideration to be successful under either scenario. If one is committed to "high and fast" there is no hope of landing within a waiver dumping a main at apogee and
would have to accept that along with possibly loss of the rocket.

I've witness several people who have successful L3 certs go on to subsequently fly some pretty "sloppy" flights right after their certs. Kurt
 
I'm an experimentalist, so fly it again and let the data tell the tale.

The body tube to NC joints, and body tube to boat tail joints need snugged up too...they were too sloppy, which would only exacerbate any problems provided by off-linear forces.
 
OK, I am really upset about leaving the camera on the rocket now. IT DIDN'T RECORD! It was on because the battery is dead, but there is absolutely no data on the card. I have no on board video to show or analyze. Kinda pissed right now, not gonna lie. This was almost surely user error, but I'm going to do some testing on that camera, and that thing won't get out of it "alive" if it isn't working correctly.

Anyhow, what I did get.

Some lift off pics from the GoPro at the pad, and some from my camera back at the flight line.

From my pics from the flight line I can say that the spinning was very minor through the first 1.5 seconds. I can see the shroud, and it only spins a bit more than 90 degrees in the 1.5 seconds after leaving the rod.

Just in case anyone is tempted to make an accusation of cover up type joke, it is way too soon.



 
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I shouldn't be surprised anymore but those pictures are jaw-dropping. You definitely went for the whole enchilada for L3. SA-LUTE !


sa-lute.jpg
 
Thanks. I cheat on my liftoff pics. There is no minimum standoff distance for a GoPro.
 
Chris I feel for you - I'm n the same boat - my onboard died sitting on the pad too long - so I have a crappy cell video of take off - and my memory and that's it for my big flight arggg. 😖
 

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