When is tumble recovery legal?

[kruland]

I was wondering if there are specific rules in the pink book which defines when tumble recovery is legal? If I use staging in a model, do the boosters need streamer or chute recovery?

I've heard that ejecting motors is not legal, but what about a motor casing with a streamer attached?

Thanks

Kevin

[kjohnson]

Short Answer: Any time it's not prohibited by the specific event rules. (i.e. you have to use a streamer in streamer duration)

In events that allow staged entries (normally altitude events and craftsmanship events) you can tumble the booster, but if it streamlines in and presents a saftey concern, it could be ruled a DQ. In the real world this means you should have flown the model before and know that the booster would tumble, and if not make modifications as needed (adding a streamer, changing the fins, length, etc to make it tumble).

Yes rule 9.2 prohibits ejecting motors without a recovery device:
9.2 Ejected Motors
No entry in sanctioned competition shall eject its motor or motors in flight in such a manner that the spent motor casing or casings fall freely apart from the model. Ejected motor casings must descend with an attached and fully deployed streamer or parachute. The streamer area must be no less than 10 square centimeters for each gram of jettisoned mass; the parachute area must be no less than 5 square centimeters per gram of jettisoned mass.

[chanstevens]

There has been a tendency the past couple of years to DQ more and more "tumble" recovery flights as unsafe, though, so it's generally a good idea to at least deploy a token recovery device.

[kruland]

Short Answer: Any time it's not prohibited by the specific event rules. (i.e. you have to use a streamer in streamer duration)

In events that allow staged entries (normally altitude events and craftsmanship events) you can tumble the booster, but if it streamlines in and presents a saftey concern, it could be ruled a DQ.

Would this be allowed in duration events too?

There has been a tendency the past couple of years to DQ more and more "tumble" recovery flights as unsafe, though, so it's generally a good idea to at least deploy a token recovery device.

Does the 9.2 rule place a limit on the size of the recovery device for boosters as well? That is, 10 cm^2 streamer per gram of mass in booster?

Thanks for the help.

Kevin

[mwtoelle]

In most duration events, except boost glide and flex wing, entries must be single-staged and must recover in one piece.

[kjohnson]

With two exceptions, the rules for duration events all say something like "open to any single-staged model rocket..." which rules out any staging.

The two exceptions are Boost Glider and Flex Wing Gliders. They can be staged, but the glider has to be part of the uppermost stage.


I copied in the whole rule about ejected engines. I don't think there is anything at all in the Pink Book about the size of a streamer for a booster.

You can check it out here: http://www.nar.org/pinkbook/

[kyntar]

Well Russia just used the tumble technique in a few of their satellites. Those might have needed streamers.

[kruland]

With two exceptions, the rules for duration events all say something like "open to any single-staged model rocket..." which rules out any staging.

The two exceptions are Boost Glider and Flex Wing Gliders. They can be staged, but the glider has to be part of the uppermost stage.


I copied in the whole rule about ejected engines. I don't think there is anything at all in the Pink Book about the size of a streamer for a booster.

You can check it out here: http://www.nar.org/pinkbook/

Thanks so much. Now I understand how to read it. In previous reads of the pinkbook, I just cruised right over the "open to any single-staged model rocket" clause.

Kevin

[Scotty Dog]

This looks legal. Not so sure on the recovery part.