Mixing Altimeters

[John A. WilkeParticipant]

What size powder charge you using. I will give you a dollar if you do the ground test. 😉 I thought I would use 3 pins.

Scott, I used four polystyrene shear pins, each 1/16″ diameter on the original KestreL (BTW, I flew this rocket under the name “benchmarK” before I renamed it “KestreL” for the 3DR kit). The drogue charge was 1.125g of bp in piece of surgical tubing. I used 0.625g for the fwd section, which had a piston.

Everyone packs things differently… we all prep charges differently, too – but you can start with that. Note that I also reefed the shock cord by taping every few loops with electrical tape. I only reefed the booster, not the upper section.

I’m also a big fan of using only ONE altimeter. I have had 3 rockets destroyed by one of 2 altimeters firing early – but I’ve never lost a rocket because an altimeter didn’t fire. I really believe one is better than two… but you gotta do what you are comfy with.

Your actual mileage may vary. 8)

[SCOTT EVANS]

What size powder charge you using. I will give you a dollar if you do the ground test. 😉 I thought I would use 3 pins.

Scott, I used four polystyrene shear pins, each 1/16″ diameter on the original KestreL (BTW, I flew this rocket under the name “benchmarK” before I renamed it “KestreL” for the 3DR kit). The drogue charge was 1.125g of bp in piece of surgical tubing. I used 0.625g for the fwd section, which had a piston.

Everyone packs things differently… we all prep charges differently, too – but you can start with that. Note that I also reefed the shock cord by taping every few loops with electrical tape. I only reefed the booster, not the upper section.

I’m also a big fan of using only ONE altimeter. I have had 3 rockets destroyed by one of 2 altimeters firing early – but I’ve never lost a rocket because an altimeter didn’t fire. I really believe one is better than two… but you gotta do what you are comfy with.

Your actual mileage may vary. 8)

OH REALLY !! 😯 One altimeter ? I didnt know. 😕
Just last night I figured out how to get 2 perfect flights in there. 😉

In the 2 flights I have had with single altimeter I have lost.
And I swear 2 of the flights with duels, the main poped with the second charge. I could be wrong, but it seamed the chute came out low.
Besides it is kinda cool to see that puff of smoke from the backup charge when you already safely under chute.

[John A. WilkeParticipant]

This is truly a topic that people have strong feelings about. I really prefer to fly a single altimeter, but everyone must do what they are most comfy with. There are sure times I have flown with 2, but it is pretty rare. I’m running low on ematches so I’m being a bit more selective…

BTW, I saw someplace where the current Tripoli altitude rules state that if you DO use two altimeters on an altitude attempt, you are bound by the lower reading. That is an interesting twist!

Is it true that the altitude from a DC20 is actually stored / downloaded from the handheld? For the first time, you can get a pretty good idea on how high your core-sampler flew 😀

[Chris LaPanse]

This is truly a topic that people have strong feelings about. I really prefer to fly a single altimeter, but everyone must do what they are most comfy with. There are sure times I have flown with 2, but it is pretty rare. I’m running low on ematches so I’m being a bit more selective…

BTW, I saw someplace where the current Tripoli altitude rules state that if you DO use two altimeters on an altitude attempt, you are bound by the lower reading. That is an interesting twist!

Is it true that the altitude from a DC20 is actually stored / downloaded from the handheld? For the first time, you can get a pretty good idea on how high your core-sampler flew 😀

Yes it is – here’s the track from my AMRAAM on its Oktoberfest flight for example:

[edwardModerator]

The DC-20 does record altitude. You do have to subtract out ground elevation as it reads ASL. I looked at my L3 shot and was amazed when it was reading in the 32’s and 33’s. Then I remembered I had to take out how high we were above the ground 🙂 Brought me back to reality.

I like John prefer a single altimeter (though someone said I had to have 2 for my L3 🙂 ). Less things to screw up. In all my flights with electronics it has never been the failure of the electronics to fire the charges at the proper times. It has always been my adeptness at learning new ways to make the recovery harness tangle, twist, wad up or otherwise not deploy when the charge fires.

As I’ve progressed recovery is the hardest part of a rocket…the up part is easy, but designing a simple, elegant functioning recovery system within the material and volumetric constraints is difficult.

Edward

[SCOTT EVANS]

This is truly a topic that people have strong feelings about. I really prefer to fly a single altimeter, but everyone must do what they are most comfy with. There are sure times I have flown with 2, but it is pretty rare. I’m running low on ematches so I’m being a bit more selective…

BTW, I saw someplace where the current Tripoli altitude rules state that if you DO use two altimeters on an altitude attempt, you are bound by the lower reading. That is an interesting twist! 😀

If you used only one, thats probably the one you would have had in there any way! 😆

[SCOTT EVANS]

😆

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