Open rocket Tumble event? (not a warning)

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Nytrunner

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I found something in Openrocket I've never seen before.
I'm sending my mammoth up on a G33 and adjusted the parachute opening to reflect the chute release I'll use (no main deploy at half a mile up please)

I imagined I'd have to make a sudo-chute to simulate the airframe tumble so it didn't just sim as coming in ballistic until release. All my previous sims threw the "Depoloyment at high speed" warning as expected, but the G33 gave me a green checkmark. Upon inspection of the flight plot, it's showing this "Tumbling event" which matches actual recovery behavior amazingly well!

What is the deal here? What criteria does OR use too determine "Tumbling"? Some conbimation of length, static margin, and low weight, that I happen to have magically hit upon by throwing a G33 in the mammoth?

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upload_2019-1-5_13-28-27.png

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rharshberger

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I wonder if it could be something like tail sliding, that long rocket with "lower thrust", might bring it to near zero motion at apogee and the rocket start tail sliding on descent (kind of like watching Frank Burke's big foamies, they are really high drag and low mass and tend to just stop at apogee and then fall tail first till the altimeter fires the ejection). Just a WAG on my part.
 

MikeyDSlagle

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My tumble events usually result from instability and happens during boost; but that throws a red exclamation point.
So...don't know.
 

Nytrunner

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Exactly, which is what I'm familiar with.

I have never seen an event flag like this
 

boatgeek

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What does the stability plot look like? Maybe it's close enough to zero stability that something magical happens?

I've seen that "Tumbling" flag before, but only on boosters of two-stage projects after booster separation. That made a lot of sense since there's an event that changes stability.
 

Wallace

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I've managed to make it do this;)
20170526_045310.jpg
 

rharshberger

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I found something in Openrocket I've never seen before.
I'm sending my mammoth up on a G33 and adjusted the parachute opening to reflect the chute release I'll use (no main deploy at half a mile up please)

I imagined I'd have to make a sudo-chute to simulate the airframe tumble so it didn't just sim as coming in ballistic until release. All my previous sims threw the "Depoloyment at high speed" warning as expected, but the G33 gave me a green checkmark. Upon inspection of the flight plot, it's showing this "Tumbling event" which matches actual recovery behavior amazingly well!

What is the deal here? What criteria does OR use too determine "Tumbling"? Some conbimation of length, static margin, and low weight, that I happen to have magically hit upon by throwing a G33 in the mammoth?

View attachment 370687
View attachment 370688
View attachment 370689
Was it your Mammoth on a G33 I saw a onboard video for? Where it basically did a tail slide to landing when the JLCR opened but the chute didn't unfurl? If so what was the apogee event like and did it relate to the OR sim in any way?
 

Nytrunner

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It was! The apogee event looked pretty normal. A little sideways thanks to weathercocking, but normal. And yes I think without the nosecone, T3, and chute bundle flailing around, it may have been interesting to see what would happen
 

rharshberger

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It was! The apogee event looked pretty normal. A little sideways thanks to weathercocking, but normal. And yes I think without the nosecone, T3, and chute bundle flailing around, it may have been interesting to see what would happen
Its pretty common for long thin rockets like the Mammoth and the Mean Machine to do a tail sliding glide. Was the tail just a tad higher than the body as it glided back? Somebody actually wrote a tech paper about the tail sliding glide behavior and how to get it to happen by design.
 

Nytrunner

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Judging by the nice aerial views of Redearch park (camera towards ground), I'm going to say the tail was pointed down and lower than the body.

The culprit......probably my cord arrangement honestly

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