Staging Timers for 2 stage rocket
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dixontj93060
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I'll be completely honest, this is not a timer problem. This is a rocket design problem. Again, how do you know that the instability point wouldn't happen at 1000ft and past a minimum velocity--in fact, it could. Then your altimeter would be saying everything is OK and you'd be firing the second stage randomly any direction. Somehow an unstable rocket got past the RSO.
dixontj93060
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BTW, Jason, not saying that your upgrade of QCRS safety and launch process has not been a great thing--it has!! I'm just saying that electronics are only part of an overall issue. People flew timers for decades successfully. Take a look at past issues of Extreme Rocketry. Their airframe and motor designs were solid, which I'd argue is 90% of the issue.
I believe the cg to cp were a little off the norm, guarantee the cg was too far back but and I would have used at least a 550 avg thrust at liftoff.
I like 2 stagers to leap off the pad.
I don't think someone simmed that one.
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OK, I'll throw myself under the bus here. I RSO'd that flight. The flyer had all sorts of flight simulation paperwork that showed everything to be OK. Obviously I missed something. I DID make him mark it a heads up flight. But, I seem to be human, so I also learned from this flight.
Adrian
dixontj93060
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Hey Adrian, let's go toast with Diet Coke!
We all make mistakes (and I have been drinking far less lately)! So I'm with ya!
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Hey Adrian, let's go toast with Diet Coke!
Yeah, we gotta do dinner (or lunch!) at MWP... I also lost (and found again...) your bell nozzle motor retainer to return to you. I put it somewhere where I wouldn't forget it, and proceeded to look right past it for a whole week... I'm getting CRS...
Adrian
I'll pile on with the others who advise caution. 3inch staged rocket with almost 11,000 N-s. You're talking about a 50,000ft Mach 2 flight. I should know, I'm building something similar and I've been simming the dickens out of it.
You'll be spending over $600 just on rocket fuel alone, and you want to save money by skimping on electronics? Electronics that make this extreme flight safer? Pony up the cash and get something that does tilt sensing. Or don't, and fly it at BALLS, which you might have to anyway due to the altitude you'll get.
You can also build electronics that do all this. I just finished an R&D project that won at NARAM this year. It did 2-stage tilt-sensing, collected more data than a Raven, but only needed an Arduino.
You'll be spending over $600 just on rocket fuel alone, and you want to save money by skimping on electronics? Electronics that make this extreme flight safer? Pony up the cash and get something that does tilt sensing. Or don't, and fly it at BALLS, which you might have to anyway due to the altitude you'll get.
You can also build electronics that do all this. I just finished an R&D project that won at NARAM this year. It did 2-stage tilt-sensing, collected more data than a Raven, but only needed an Arduino.
I agree with Tim, this definitely was fraught with design in-stability.
I also do think the booster was a little under powered which compounded the stability issues.
From what I can hear off the video, it seems the booster was an EX motor, that probably wasn't characterized properly and contributed to the inaccurate simulations.
From the little information provided, I can't blame the RSO for this. If the guy had all the sims showing everything was good, and everything else checked out with no glaring errors, I would think the RSO did his job.
I also do think the booster was a little under powered which compounded the stability issues.
From what I can hear off the video, it seems the booster was an EX motor, that probably wasn't characterized properly and contributed to the inaccurate simulations.
From the little information provided, I can't blame the RSO for this. If the guy had all the sims showing everything was good, and everything else checked out with no glaring errors, I would think the RSO did his job.
dixontj93060
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I agree. Tough to argue sims cold. But if EX then yes, may have missed on the characterization. Regarding RSO, Adrian is just too nice. Some of us 6'-2", 250lb lugs should be RSO bouncers to get tough with the marginal flyers. Yeah, that's it--a new volunteer slot RSO Bouncer! BTW, Bob Brown from Kloudbusters is honorary first Hall of Fame inductee
!
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Damn. Good thing it pointed away from the flight line.
CORZERO
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Thanks for being honest, ya big lug! I think you're right. This was not a timer problem but rather an EX motor/stability problem. However, if proper electronics rather that a dumb timer were used the potentially hazardous outcome would have been prevented.
CORZERO
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Yeah no $h1t right?!!! That sustainer SCREAMED!
I keep watching this video and making audio adjustments. Is it just me or is that a supersonic CRACK milliseconds after it flies out of the frame????
This is why I was advising that your first attempt at staging shouldn't be a flight profile of this magnitude.
ColumbiaNX01
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This is where your mistaken. The total N are 10,329 not 11,000. Rasearo is siming anywhere berween 34000 and 39,000. If it where going any higher then 40,000 I would not bother with that motor combo. I want to keep it at 40,000 or less. The total cost of the motors is only $476.23 give your take 20 bucks. Thats for a L1090 and M1850. Not over $600.
Everyone around here likes the numbers to be more exact. So next time you try to dis me, make sure your numbers are accurate. Thanks
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Andrew,
I don't know if you will be flying this project at the Rocket Pasture or in Oklahoma but here are the Kloudbuster rules for staged flights.
https://www.kloudbusters.org/images/stagerules.pdf
Good Luck,
I don't know if you will be flying this project at the Rocket Pasture or in Oklahoma but here are the Kloudbuster rules for staged flights.
https://www.kloudbusters.org/images/stagerules.pdf
Good Luck,
ColumbiaNX01
Red blooded white American male
Thanks yea. I have filled that form out a few times over the years. yea i am leaning towards the Missile Works rrc3. That altimeter is user friendly. yes I would be flying it in argonia. I like that altimeter because you set a velocity and/or altitude so that if rocket does not reach that pre set mark the sustainer does not fire.
Not attempting to be exact here, and depending on where you source the information you can have a variance of 100 NS or so but, there are two different L1090's, the AT is around 2,700ns, the CTI is around 4,800ns. there are also two different M1850's, the AT is around 7,600ns, the AMW is around 5,920ns. I'm making a scary assumption here that you have better motor information than I do, but if you are using the AT loads and that would be a total of around 10,300ns. I would get this information clarified for certain before running any sims that would be considered accurate.
I see you have now edited your post and changed the total Ns from your original 8,087 to 10,329. Guessing you know that the additional 2,241.4 NS and the additional propellant weight will change the sims more than a tad also. Remember accuracy, accuracy, accuracy. This just goes to my original point that a flight profile of this magnitude should NOT be someone's first attempt at a staged flight, regardless of what type of electronics are on board.
ColumbiaNX01
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Yea the sim is still the same. I just looked on the wrong motor in thrust curve. the sims still are the same. I am not for altitude. once the booster burns out then I am gonna light the sustainer with only a 1 second delay. Yes if I waited longer it could go 40K plus.
You're more than welcome to fly whatever the RSO agrees to go to the pad.
A lot of us at MDRA take an approach of testing with a set of smaller motors, depending on your total weight. Maybe start with a L or full K to a J or baby K.
Great place to start testing altimeters, staging device and deployment to tracking, you'll need that at 30k-40k.
Not a sermon, just a thought.
PS-my profile pic is staged with a PML timer and never has failed. But that was a J820 staging to a E50, much smaller than the subject here.
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ColumbiaNX01
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You know what is great is I have all the cases I would need. I could do a L to baby k. But Its all the same really except your putting up more newtons. Same rocket just smaller motors. Something bad can happen with smaller motors to. A M to L could wore flawlessly then if your doing a L to K the L could cato on the pad. Bad things can happen regardless.
I am getting on my soapbox now. Man went to the Moon with the mentality of leap without looking. Something NASA and the USA has lost. Not saying it is a bad thing to be cautious, but if you have a goal and you take all the safety aspect into play then what is truly holding you back?
Just saying- when NASA was "leaping without looking" they killed 3 people while still on the ground. Afterwards, they rethought their approaches, and took small incremental steps to get people to the moon safely.
*Edited*.. and when they decided later on that safety was secondary to getting something in the air, they killed 7 more.
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CzTeacherMan
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ColumbiaNX01
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You have to understand what I meant by that. Man went from launching one astronaut on top of a rocket that was supposed to be used for a nuclear weapon in the early early 1960's and in 1969 landed on the moon. All that in a decade. Thats what I mean leap without looking. Because what after the Apollo program was scrapped aft 1972 we have not done anything. Its what 2016 and we have not visited anywhere else besides earth orbit. Its been 44 years since then. What do we truly have in a manned space program now. Its very sad.
CzTeacherMan
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Might have something to do with a certain political party cutting funding to scientific endeavours because... Etc etc... And I agree, it's very sad.
JimJarvis50
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Careful with that 1 second approach. I've had motors take 6 seconds to come up to pressure. If you get such a delay, you might go much higher than you expect. You can run a simulation so that you know what might happen.
Jim
ColumbiaNX01
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Yea I have been playing around with the sims. What is your good rule of thumb Jim?
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JimJarvis50
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I don't really have any rules of thumb. I'd say at 25 to 40K, 4-6 seconds is typical. I think the motors with pellets (N1100's for example) are a bit faster. I always "enhance" the igniter with pyrogen or pyrodex or whatever, with maybe 3 times the energy that you might use on the ground. It's just sort of an educated guess.
Jim
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