Attempting the K and L altitude records

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watheyak

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Why not a Raven? It has a proven track record on flight like this. Especially in cases where the static Port is pointed I to the relative wind such as on a nosecone. Not sure if yours is like that, but mine always are.
 

T34zac

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No joke about upper altitude wind speeds. Download the Windy app on your phone. It will give you a much better idea of how much drift you will get. For example, right now my surface winds are 15mph and also 15mph at 35,000' But, 100 miles west the winds at 35,000' are close to 70 mph. You open a main at that altitude and that wind speed and your bird will be 30-40 miles away by the time it lands.

Use a chute release on the main and a small drogue that brings it down at about 40-50 mph. I know it's for an altitude record, but it won't add much weight, especially if you use thin mil chutes, and will make recovery much less challenging. You can always ditch the chute release and drogue on a future flight for more altitude, but I doubt it would make much difference either way. You can sim it to determine the relative difference.
I did use the windy app to help out. Upper level winds on Friday morning were only around 30mph IIRC. But just below that the winds were going in the complete opposite direction. Either way the rocket didn’t fly and dual deploy is going to be added for TRAPHX flights.
 

T34zac

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Why not a Raven? It has a proven track record on flight like this. Especially in cases where the static Port is pointed I to the relative wind such as on a nosecone. Not sure if yours is like that, but mine always are.
I like the Raven for the capabilities they provide in such a small package. But losing them over and over gets expensive. Just this year I’ve toasted four of them in various ways.
 

dvdsnyd

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I’ll definitely be using that in the future, thanks for sharing!
No problem, I'd be really interested to see how well it works for you. Let me know if you have any questions or problems with it.
 

wsume99

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Random thought as I was following the discussion ... how does the descent rate change with altitude? I've never noticed a significant difference in descent rate on my flights but they are all under 5k feet. If you are going up to 30k feet I'm assuming the density reduction will have some effect. Does anyone have data from actual flights to shed some light here? Unless the main opened at apogee I doubt there will be many that do.
 

Mike Haberer

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Random thought as I was following the discussion ... how does the descent rate change with altitude? I've never noticed a significant difference in descent rate on my flights but they are all under 5k feet. If you are going up to 30k feet I'm assuming the density reduction will have some effect. Does anyone have data from actual flights to shed some light here? Unless the main opened at apogee I doubt there will be many that do.
Descent will be faster at higher altitudes but will slow down as you drop. You can sim it in OR or Rocksim by setting your launch altitude to 30,000' and see what your landing speed is for the chute you are using, then compare that rate to the landing speed at your ground level sim.
 

Buckeye

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After you sim it in OR or RS, plot velocity vs. altitude to see the relationship.
 

T34zac

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Revised the Av-bay tonight. Easy Mini and Featherweight GPS now live in the av-bay. Next up is a hot wire cutter for dual deploy.
 

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T34zac

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Hot wire cutter. Nicrome wire wrapped around a beaded cable tie. When the easy mini “fires” the main charge, it heats the nicrome wire long enough to melt the cable tie that’s holding the parachute closed. Basically a cheap, compact, and lightweight version of a cable cutter.
 

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Buckeye

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How long is the current flowing to the nichrome wire? Is this latch time (is that the correct term?) adjustable in the easy mini?

Does the chute get a little burned/melted also?
 

dvdsnyd

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Along the same lines as Buckeye, my question - have you tested your cable cutter configuration?
May also not be a bad idea to test it right in front of a box fan set on high. You'll have some wind potentially impacting the heating of your nichrome wire.
 

T34zac

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How long is the current flowing to the nichrome wire? Is this latch time (is that the correct term?) adjustable in the easy mini?

Does the chute get a little burned/melted also?
Along the same lines as Buckeye, my question - have you tested your cable cutter configuration?
May also not be a bad idea to test it right in front of a box fan set on high. You'll have some wind potentially impacting the heating of your nichrome wire.
I still need to test it with the easy mini just to be sure, but previous testing has shown me that it tends to work within a half second.

I’ll have something in between the parachute and nicrome for the actual flight, maybe a piece of tape on the parachute, stuck there before folding and adjusted so it’s against the nicrome.

The box fan test idea isn’t terrible, I’ll see if I can get something like that together, but this is a proven method of deployment I’ve used before.
 

dvdsnyd

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I still need to test it with the easy mini just to be sure, but previous testing has shown me that it tends to work within a half second.

I’ll have something in between the parachute and nicrome for the actual flight, maybe a piece of tape on the parachute, stuck there before folding and adjusted so it’s against the nicrome.

The box fan test idea isn’t terrible, I’ll see if I can get something like that together, but this is a proven method of deployment I’ve used before.
Good to hear!
I thought too afterwards, that it looks like you wrap your nomex around the parachute after the zip tie/nichrome cutter. If that's the case, the nichrome won't be as exposed to the wind.

In my experience with cable cutters. Commercially available by Prairie Twister and my own 3d printed variants. I burrito wrap the heck out of the chute and attach the zip tie/cutter combo over that.

Either way, looks like you are well on your way! :) Hoping for your success!
 

JackC

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And here’s the finished rocket put together for its final assembly before heading to Black Rock in a couple days.
View attachment 481784

Future plans include:
- L265 at Tripoli Phoenix to attempt the L record (pending success of the K300 attempt)
- K1440 at Tripoli Phoenix, trying to break Mach 3.5 (going to build a new fin can for that)
- K2045 at LDRS 40. I’ve got a friend who has one, and wants to see it on something that’s a “full send”
That is a sexy beast!
 
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