I usually use different altimeters. Perfectflight MAWD or HiAlt45 plus a Missileworks RRC2X or mini-RRC - I've even flown Adrian's 1st generation altimeter - the Parrot along with 2 others. Never a problem with that.

On the other hand, altimeters in close proximity to transmitters are definitely problematic. Typically I put flight avionics in the coupler and tracking beacons or GPS telemetry in the nose.

Warren

I don't think that electrical interference will be a problem. I haven't found a case yet in which there is any discernible effect on the Raven from a transmitter or other electronics. Having a beeline transmitter in close proximity to to a Raven does not affect the baro data like it did for the Parrot altimeter.

Some people are concerned about making sure that 2 charges don't go off at the same time in the same tube. If you want to avoid that, you can put a delay on the Raven's deployment charge for apogee, and use a different altitude setting for the two altimeters for the main deployment.

That has kept me from using two Perfectflites!

The Raven is more adjustable. I expect you could use two Ravens in tandem.

Being able to adjust the apogee charge is a really cool benefit to the Raven.

Thanks. You can also use a single Raven, with its four default output settings, to do both primary deployments and both backups with one altimeter. The default apogee output is accelerometer-based, and the default 3rd output is set up to use a baro-based backup with a delay. The 4th output is set up to deploy at altitude, with a delay. This setup makes a setup single-fault-tolerant to most (but not all) faults. You would be covered for a bad ematch, dud charge, output wiring failure, or a sensor failure. You still need the battery that powers the logic, and the microcontroller, to work.

Some people are concerned about making sure that 2 charges don't go off at the same time in the same tube.

I often use one charge if I'm using two altimeters. If your systems fail (batteries or altimeters or ematches or whatever), that is one thing. If you got your powder from the same source, it is either good or it is bad. If it is GOOD, the 2nd altimeter will light it. If it is bad, neither will light it.

If you did wire two separate charges from 2 different altimeters, the odds of them detected the agogee to the millisecond are pretty remote anyway. There have been a lot of articles written on that. You'd probably be fine...

I have used 2 RRC Minis. I set the back up with a delay of 2 or 3 seconds at apogee and the back up on main chute at 3 to 500 feet lower than the primary atimeter. 2 switches 2 Batteries 2 altimeters 2 pairs of charges. Total redundancy. I wondering about the room in the ebay in that Kestrel. 🙄

I have used 2 RRC Minis. I set the back up with a delay of 2 or 3 seconds at apogee and the back up on main chute at 3 to 500 feet lower than the primary atimeter. 2 switches 2 Batteries 2 altimeters 2 pairs of charges. Total redundancy. I wondering about the room in the ebay in that Kestrel. 🙄

Plenty of room!! gosh, I'm not used to having so much room. I feel like I could stuff a loaf of bread in there! I think you could probably squeeze between 75 and 100 Ravens in there 😀

If you need more room, I'll get you a longer coupler and a longer fwd section. Try it out first, I think you will be fine.

The ebays for those 24mm, 29mm, and 38mm rockets can be tough. I felt like I was trying to jam a sparrow's nest into the last 24mm that I did.

I have used 2 RRC Minis. I set the back up with a delay of 2 or 3 seconds at apogee and the back up on main chute at 3 to 500 feet lower than the primary atimeter. 2 switches 2 Batteries 2 altimeters 2 pairs of charges. Total redundancy. I wondering about the room in the ebay in that Kestrel. 🙄

Plenty of room!! gosh, I'm not used to having so much room. I feel like I could stuff a loaf of bread in there! I think you could probably squeeze between 75 and 100 Ravens in there 😀

If you need more room, I'll get you a longer coupler and a longer fwd section. Try it out first, I think you will be fine.

The ebays for those 24mm, 29mm, and 38mm rockets can be tough. I felt like I was trying to jam a sparrow's nest into the last 24mm that I did.

For 2 ??
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.

For 2 ??
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.

When you use small altimeters and batteries, you might be surprised how much you can pack into a small space. This 38mm av-bay has 2 Parrot altimeters, 2 batteries, 4 screw switches, and a transmitter:

http://www.rocketryplanet.com/forums/showthread.php?t=2409

It's about 3" long.

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)

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.

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 😀

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:

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