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Have searched, haven't found anything on-point, so another new-guy post this afternoon.
I've been playing a little in OpenRocket with a 24mm minimum diameter build while I wait for parts to arrive for my 18mm. Looking at the AeroTech F32-8T. I was liking the numbers with an E9-8, but the F32 numbers are interesting. A whole 'nother level, obviously. But there are some issues, mostly with recovery.
First off, assume launching on a dry lake so the thing will be findable. The mirage dries up when you get close. And I don't mind wandering around in the desert, for some reason. Dirt bikes are fun.
I'm getting a 21-22 m/sec velocity at deployment on the F32-8T. OpenRocket throws a warning flag on the sim when you exceed 20 m/sec, or about 45 mph. The range of Estes C/D/E motors I've simmed on this one give 1-12 m/s, so pretty reasonable.
I'm thinking that a streamer will roll out progressively and more gently ramp up the drag force, rather than popping out and snapping from zero to max drag all at once like a chute. I suppose I could toss a streamer out the window of my car on a shock cord at 50 mph and see what happens. Don't want to zipper the tube, obviously, and really don't want to end up with a lawn dart, partial streamer, etc.
I can obviously tweak the model this way and that to slow it down, but then that carves away at the performance and lighting $20 bills on fire just isn't as exciting.
The sim is also showing 18.6 m/sec descent speed on a streamer. Fins are G10 glassed to the tube and reasonably protected by the stickout of the engine for a nozzle-first landing. The AeroTech engine has a thrust collar built in, and with both that and an engine block glued into the tube, I reckon it should be OK. The calculator at rocketreviews targets 17 m/sec, so that's at least livable. I can always make the streamer a little bigger to cut down the descent speed, but that also increases the risk of problems due to premature ejectuation.
I guess I'm looking for experienced feedback on how bad 22 m/s streamer ejection speed is with a streamer. I'd be forgetting about this and moving on if I was only thinking parachute. Is the speed with a streamer just something to be cautious about and engineer around with a longish Kevlar shock cord and zippering protection measures, or is the 20 m/s a wall that shouldn't be passed?
I'm aware of things like controlled ejection independent of the motor, and obviously this illustrates why they are valuable, but that takes things into a level of complexity and expense that I'm not really interested in getting into any time soon.
I've been playing a little in OpenRocket with a 24mm minimum diameter build while I wait for parts to arrive for my 18mm. Looking at the AeroTech F32-8T. I was liking the numbers with an E9-8, but the F32 numbers are interesting. A whole 'nother level, obviously. But there are some issues, mostly with recovery.
First off, assume launching on a dry lake so the thing will be findable. The mirage dries up when you get close. And I don't mind wandering around in the desert, for some reason. Dirt bikes are fun.
I'm getting a 21-22 m/sec velocity at deployment on the F32-8T. OpenRocket throws a warning flag on the sim when you exceed 20 m/sec, or about 45 mph. The range of Estes C/D/E motors I've simmed on this one give 1-12 m/s, so pretty reasonable.
I'm thinking that a streamer will roll out progressively and more gently ramp up the drag force, rather than popping out and snapping from zero to max drag all at once like a chute. I suppose I could toss a streamer out the window of my car on a shock cord at 50 mph and see what happens. Don't want to zipper the tube, obviously, and really don't want to end up with a lawn dart, partial streamer, etc.
I can obviously tweak the model this way and that to slow it down, but then that carves away at the performance and lighting $20 bills on fire just isn't as exciting.
The sim is also showing 18.6 m/sec descent speed on a streamer. Fins are G10 glassed to the tube and reasonably protected by the stickout of the engine for a nozzle-first landing. The AeroTech engine has a thrust collar built in, and with both that and an engine block glued into the tube, I reckon it should be OK. The calculator at rocketreviews targets 17 m/sec, so that's at least livable. I can always make the streamer a little bigger to cut down the descent speed, but that also increases the risk of problems due to premature ejectuation.
I guess I'm looking for experienced feedback on how bad 22 m/s streamer ejection speed is with a streamer. I'd be forgetting about this and moving on if I was only thinking parachute. Is the speed with a streamer just something to be cautious about and engineer around with a longish Kevlar shock cord and zippering protection measures, or is the 20 m/s a wall that shouldn't be passed?
I'm aware of things like controlled ejection independent of the motor, and obviously this illustrates why they are valuable, but that takes things into a level of complexity and expense that I'm not really interested in getting into any time soon.