Ground tests of recovery systems

[TWRackers]

So I'm curious... how do you usually test your recovery systems? Pull a vacuum on the e-bay so the altimeters believe the rocket is ascending and descending, or use an altimeter test mode to fire the pyros without simulating a change of altitude?

Admittedly, the first option would not apply to accelerometer-based altimeters.

 

[jadebox]

So I'm curious... how do you usually test your recovery systems? Pull a vacuum on the e-bay so the altimeters believe the rocket is ascending and descending, or use an altimeter test mode to fire the pyros without simulating a change of altitude?

Admittedly, the first option would not apply to accelerometer-based altimeters.

I hook the ematch up to a launch controller and push the button .....

-- Roger

 

[ben_ullman]

I hook the ematch up to a launch controller and push the button .....

-- Roger

I agree. I have never "felt the need" to test my altimeters baro functions. hook up Ematched charges and run wires out the vent hole and I put the wires in a 10 foot extension cord, female end, and touch a 9V to the male end. works great.

Ben

 

[ggoldy]

Hi Tom, Gary (SEARS) here
I drew a vac on mine to sim as close to real conditions as possible on the ground. Made me feel more better. Flew my first duel deploy two weeks ago. A bt80 based test rocket. Cheap and light. Vid on our web page. We always have a good crowd and I don't want to be the one to drop a rocket on some one. Used the away cell and pointed it even farther from the flight line. Now, to finish my upscale Solar Sailer(38mm PML inner tube and 2" quantum tube outer). Duel deploy and my first hybrid.

Gary

 

[WillMarchant]

I feel you need to do both, but not necessarily in the same test.

You need to be convinced that your altimeter(s) will fire the e-match(es) in the configuration that you'll use. That does not necessarily have to include the gas generation charge.

I think you need to verify that you altimeters are functioning through any e-bay internal harness out to connectors on the outside of the e-bay for many different reasons. This can be accomplished with light bulbs. For a barometric only altimeter you can suck air out of the e-bay to test. For an accelerometer based system you're stuck using internal simulation modes to drive your harness. I think this test is particularly important to verify that apogee and main wiring is not confused.

You need to be convinced that the e-match and gas generator of your choice will actually deploy your recovery system. This can be accomplished with a launch system.

You can't get a perfect simulation on the ground. But if you test the sub-systems properly I think you can get close enough.

 

[ben_ullman]

I feel you need to do both, but not necessarily in the same test.

You need to be convinced that your altimeter(s) will fire the e-match(es) in the configuration that you'll use. That does not necessarily have to include the gas generation charge.

I think you need to verify that you altimeters are functioning through any e-bay internal harness out to connectors on the outside of the e-bay for many different reasons. This can be accomplished with light bulbs. For a barometric only altimeter you can suck air out of the e-bay to test. For an accelerometer based system you're stuck using internal simulation modes to drive your harness. I think this test is particularly important to verify that apogee and main wiring is not confused.

You need to be convinced that the e-match and gas generator of your choice will actually deploy your recovery system. This can be accomplished with a launch system.

You can't get a perfect simulation on the ground. But if you test the sub-systems properly I think you can get close enough.

As usual Will is spot on

Ben

 

[MarkM]

I hook the ematch up to a launch controller and push the button .....

-- Roger

I do the same. What you really are testing is if the amount of BP you load can effectively separate the tubes or NC. I always test in a "flight ready" configuration with shock cords and chutes loaded and connected.

Testing the altimeter should be a separate testing to determine if it will fire the ematch,although I rarely have tested my altimeters. I just haven't felt the need except when switching to a different ematch brand.

BTW...I didn't vote in the poll. Neither choice is appropriate to the way I test. You need at least one other choice to reflect the method that I, Ben, Roger and Will apparently use.

 

[TWRackers]

BTW...I didn't vote in the poll. Neither choice is appropriate to the way I test. You need at least one other choice to reflect the method that I, Ben, Roger and Will apparently use.

In that case, is there a way I can edit the poll choices? If so, I can't find it.

 

[Fade_to_Black]

As usual Will is spot on

Ben

I'll second that!

 

[blackjack2564]

I always let a new altimeter ride along with a proven one on it's first flight . Fly at an altitude where events can be seen. Set the new one as the secondary and look for the puffs of smoke indicating all went well for both events. Then check altitudes for consistency upon landing.

 

[WillMarchant]

In that case, is there a way I can edit the poll choices? If so, I can't find it.

Dunno if you can edit it, Tom. But I can. Did you want to add "Both" and "Neither" as possible answers?

 

[WillMarchant]

I'll second that!

Thanks, Guys!

Boy, I hate recovery mistakes. I spend a lot of time obsessing over it. But some days you get the bear and some days the bear gets you!

 

[TWRackers]

Dunno if you can edit it, Tom. But I can. Did you want to add "Both" and "Neither" as possible answers?

Sure, why not.

 

[Diosces]

I voted testing by making a pressure change via tubing to the EBAY. It's how I been testing and works out well.

 

[jadebox]

I tested my Parrot altimeter (which was set for accelerometer-based apogee detection) once by connecting an e-match to it then swinging the ebay around in a circle. I stopped when I got dizzy and almost fell over. I disappointed that when I stopped, the match didn't fire. Then, a second later, pop, it fired!

I really hope my neighbors aren't watching the things I do in my back yard.

-- Roger

 

[ben_ullman]

Thanks, Guys!

Boy, I hate recovery mistakes. I spend a lot of time obsessing over it. But some days you get the bear and some days the bear gets you!

Does it make it easier when you crash something and someone else fixes it? Sat V rebuild #2 under way !!

Ben

 

[Handeman]

Does it make it easier when you crash something and someone else fixes it? Sat V rebuild #2 under way !!

Ben

Not to steal the thread, but Ben, are you going to do a "repair" thread on the Saturn? It might be useful to some to know how to do repairs vs. builds.

You don't have to explain how it crashed, just how it was fixed.

 

[Adrian A]

I tested my Parrot altimeter (which was set for accelerometer-based apogee detection) once by connecting an e-match to it then swinging the ebay around in a circle. I stopped when I got dizzy and almost fell over. I disappointed that when I stopped, the match didn't fire. Then, a second later, pop, it fired!

I really hope my neighbors aren't watching the things I do in my back yard.

-- Roger

I bet all the centripetal acceleration made it think it was going REALLY fast. It took awhile for it to think gravity was slowing it down to apogee.

You can also just give it a quick upward jerk while you hold it, but then you don't get the fun of spinning around in your back yard and falling over.

 

[cjl]

I test my altimeter and charges separately. For the charge test, I just hook an e-match to my launch controller and press the button

 

[ben_ullman]

Not to steal the thread, but Ben, are you going to do a "repair" thread on the Saturn? It might be useful to some to know how to do repairs vs. builds.

You don't have to explain how it crashed, just how it was fixed.

Its coming. I am going to start tonight/tomorrow inventory parts and seeing what I need.

And it crashed due to rushing. The rebuild will make it a 100% better rocket an make it easier to do the cluster config that I oh so like!! And I am hopingto get the nosecone down to 18-20lb.

Ben

 

[TWRackers]

Well, the good news is that I successfully ground-tested the pyros this past Sunday at our launch site. It took 2 grams of BP in a Pratt Hobbies ejection canister (the LWEC size) to cut the four shear pins (2-56 nylon screws) and send the nose/payload section skittering about 12-15 feet across the grass. (Pressurized section is 6" diameter and 24" long between bulkheads.) My blacksky ARRD also worked properly, holding the main chute's d-bag in place until I fired it. I used the USB adapter for my PerfectFlite MAWD to run a long USB cable from the assembled rocket to my laptop, and used the test mode to fire the pyros in sequence.

Now all I have to do is check the operation of the baro sensors with a vacuum jar loaned to me by one of our club members. All the wiring (from alts to external connections) have already been checked out as well.

If I get a chance I may post the video of the ground test onto YouTube. It's pretty grainy, but it's better than nothing.

 

[DexterLB]

I always simulate pressure and test if it's my scratch built altimeter. If it was a commercial one I wouldn't test anything.

 

[TWRackers]

I am rather surprised.

At the time of this post, "Neither" is winning with 11 votes over the other choices with 8, 7, and 2 votes respectively.

Maybe I should've been more specific. A NAR Level 3 certification (and probably a TRA Level 3 too, I haven't checked) requires a test of the recovery system, right? I was just wondering how most people performed this test prior to Level 3 cert attempts. Doesn't really matter now, I've already completed my tests, but still, it's a curious result.

 

[MarkM]

it's a curious result.

Several reasons.

1) Choice two is not available for many altimeters. My favorite Adept altimeter does not have any test mode.

2) Your poll question asks how you test deployment. Testing deployment, based on the comments (including myself), is really a two step process for many: (a) Testing your altimeter (if necessary) separately and then (b) testing to be sure your recovery system deploys with a determined amount of BP often without the altimeter iin the ground test loop. Part B is really what most people are interested in testing, especially when using new size airframe, a heavier one, new use of sheer pins, etc when they ground test. And they use a few different methods to do this.

However, your poll choices ONLY address altimeter testing and not what most people are actually using the ground test for ...proper charge sizes..and how they do it.

Your choices for the poll simply didn't properly address the question. So, people used the "out" choice...neither....since 1 & 2 only addressed one (or even no) part of the question. It certainly didn't for me. I don't test my altimeters since I've tested them before, used them dozens of times and I'm confident in their functioning, but I frequently need to test that my deployment charges are properly sized. Yet, no part of the poll addressed this! Quite honestly, I think your poll question was much better answered by the comments rather than by the results of the poll itself. IMO, this is the type of question that doesn't make itself easily phrased for a poll and the results you did get are very not decipherable and do not accurately reflect what people ACTUALLY do in deployment testing.

 

[TWRackers]

Yes, in retrospect I see your point. I think I was too fixated on what I considered were my two options (end-to-end test vs. simulated recovery) to consider many people don't test (or retest) their altimeters. Both of my altimeters have never been used, so I wanted to verify that they would work as intended in sensing air pressure and responding accordingly. I ended up testing those functions independently from the recovery system itself (BP charge + shear pins). At work we try to do end-to-end tests when at all possible, so that was my mindset when I was planning my tests.

 

[Diosces]

Concur, TWRACKERS End to end tests are usually the best.

And contrary to what some have indicated...once you have a solid system set-up (right size tubing, port adaptor, etc then including the altimeter in a groundtest is a no brainer. .

I do my pressurization test not for the sake of testing the altimeter but rather test the whole recovery deployment system. And it's actually easier that rigging a simulated altimeter wired output to the match for me.

 

[delta22]

I agree, a complete recovery deployment system check is the best way to check that all parts of the system work.

I use a long thin clear tube and draw a vacuum on the ebay. The rocket is assembled for flight, except that I only test one ejection charge at a time, and it is laying flat just above the grass.