Just so everybody doesn't think this was some wild wild west launch. The club who hosted this launch has learned from this and has made new carved in stone rules about 2 stage flights. No timers allowed....PERIOD.
Just so everybody doesn't think this was some wild wild west launch. The club who hosted this launch has learned from this and has made new carved in stone rules about 2 stage flights. No timers allowed....PERIOD.
Underpowered? I don't think so. Velocity looks good leaving the rail. The slowdown and flip--clearly unstable.
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.
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
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!
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.
And this is why:
[video=youtube;1VAkWgbCtA4]https://www.youtube.com/watch?v=1VAkWgbCtA4[/video]
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.
Damn. Good thing it pointed away from the flight line.
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.
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.
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,
This is where your mistaken. The total N are 8087.6 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
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.
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
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.
Man went to the Moon with the mentality of leap without looking.
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.
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.
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.
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.
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
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????
Yea I have been playing around with the sims. What is your good rule of thumb Jim?
Enter your email address to join: