Second Try, High Power Two Stage Success Video

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AndrewW

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So after a booster motor failure last fall I rebuilt my RW Double Shot called "DOUBLE TROUBLE" and flew it successfully a few weeks ago at a MDRA launch on Higgs Farm in Maryland. I flew it on a CTI J760 to a I125 and had 3 Eggtimer Quantums, an Eggfinder TRS, an Eggfinder Mini and a JLCR on board. I also wanted to say thank you to the folks at MDRA for a great launch and especially Tom C. for retrieving the booster for me and giving us a couple of Mini Higgs rocket kits. So here is a quick video:

[YOUTUBE]Fwve0UHJ-BY[/YOUTUBE]


And a link to a post and video from the last less than successful flight:

https://www.rocketryforum.com/showthread.php?142725-2-Stage-Failure-Video&highlight=stage+failure
 
Nice flight! I like the way you did this video HUD as well. I'm toying with options for my Madcow Nike Apache and really like seeing how others have gone about it.
 
I am building a Nike Apache as well. I plan on using the same Quantum sled and all that I used in the booster for the Nike which was set up for apogee deployment along with a JLCR and a stage separation charge. For the sustainer I will be using a newly acquired Raven 3 for primary deployment and sustainer ignition along with either a Quantum or something a bit smaller for backup deployment. I will also have a Eggfinder Mini in the nose cone for tracking.
 
Very nice flight. Great shot on the primary apogee failure and subsequent backup success.

Having said that, I think the rocket gods have it out for you. After everyone else, those power lines were awfully close.

Looking forward to seeing this one fly, are you going to URRF 5?
 
Thanks. I definitely learned a few lessons with this one. Although everything ground tested fine last summer I think the cold weather may have affected the primary separation fit. I usually use the same amount of BP in each charge but on this one I decided to increase the BU by 30% or so and I am glad I did. Also if you look closely it did not drag separate the way I expected which had a very loose fit so the separation charge which I considered a back up came in handy as well.

I cannot believe it cleared those lines. It actually crossed over them and then back again before just missing them.

I am definitely planning on attending URRF5. My primary focus will be on flying my L3 project but I will also be bringing this along and hope to fly it on a K to J combo. I also hope to fly my new Nike Apache 2 stage there as well.
 
Congrats you've made it work. I've only designed and flown two multistage L-1's for UTC USRC SEDS 2017, and all these old Farts were right it's not twice as hard. You've done something very few people achieve due to the effort involved.
 
Great video. Probably the best video with a data overlay that I’ve seen.


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Amazing... That was a great capture of the failed primary apogee charge. Without the video we would have never known. That confirms that I'll keep building my backup charges 20% bigger then primary. Thanks for the great video (attempt 1 as well).

What was your booster electronics/recovery? Any idea on booster altitude?
 
The booster was equipped with a Eggtimer Quantum with one channel set for deployment at Apogee which released the main chute which was held with a JLCR set for 400’. The second channel was set for stage separation at 1.5 seconds after booster burnout. I also left the motor ejection charge intact as a backup. There was also a Eggfinder Mini in there just Incase. What really surprised me was that even though the stages separated around 1200’ the booster continued on to ~2700’. I really didn’t think that an open ended tube would still fly so well.
IMG_5371.jpg
 
The overlay was done in Dashware. It was a lot of work though as most of the gauges where new or customized and it require a lot of tinkering with file formats, .csv files and data source profiles.
 
The booster was equipped with a Eggtimer Quantum with one channel set for deployment at Apogee which released the main chute which was held with a JLCR set for 400’. The second channel was set for stage separation at 1.5 seconds after booster burnout. I also left the motor ejection charge intact as a backup. There was also a Eggfinder Mini in there just Incase. What really surprised me was that even though the stages separated around 1200’ the booster continued on to ~2700’. I really didn’t think that an open ended tube would still fly so well.
View attachment 341076

I recommend placing the battery on the other side of the sled from the electronics. That way, if it comes loose it won’t destroy your electronics. I usually use multiple cable ties. I usually use two going the direction you have yours and one lengthwise, but it depends on what size and shape of the battery. And I leave the battery leads long enough that if a battery comes loose it cannot get to the end of its cable. Just some suggestions. You might not ever have a problem.


Steve Shannon
 
I really didn’t think that an open ended tube would still fly so well.
View attachment 341076

Nice flight and video!

I have a two-stager that is motor deploy on the booster. I typically do a simulation with the stages remaining attached and the sustainer not lighting. Then, I take two-thirds of the coast time to set the motor delay. It usually comes out close. So, they fly better than you might expect.

On the drag separation, you can calculate whether it will want to separate or not. A while back, I looked at the tendency to drag separate for a 4x4 and a 4x3 rocket. To my surprise, the 4x3 had less of a tendency to drag separate than the 4x4.

Jim
 
I recommend placing the battery on the other side of the sled from the electronics. That way, if it comes loose it won’t destroy your electronics. I usually use multiple cable ties. I usually use two going the direction you have yours and one lengthwise, but it depends on what size and shape of the battery. And I leave the battery leads long enough that if a battery comes loose it cannot get to the end of its cable. Just some suggestions. You might not ever have a problem.


Steve Shannon

A couple of great ideas. In this case there is a 1/4” threaded rod on the other side of the sled that holds the whole bay together and I have some industrial hook and loop tape holding the battery down.
 
Great flight and amazing video skills - that’s a big honking battery.


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Nice flight and video!

I have a two-stager that is motor deploy on the booster. I typically do a simulation with the stages remaining attached and the sustainer not lighting. Then, I take two-thirds of the coast time to set the motor delay. It usually comes out close. So, they fly better than you might expect.

On the drag separation, you can calculate whether it will want to separate or not. A while back, I looked at the tendency to drag separate for a 4x4 and a 4x3 rocket. To my surprise, the 4x3 had less of a tendency to drag separate than the 4x4.

Jim

Jim,

That is very surprising and definitely not what I would have expected. What did you use to calculate whether it would separate or not

Andrew
 
How much BP did you use for your charges? By the way great video!

I am not exactly sure how much BP was each as I have been using centrifuge vials for sometime now and using the graduated markings on them to keep track of how much to use. If I remember correctly it was about 1.2g for the primary and 1.5g for the backup in the sustainer.

As for the massive battery i originally had a 2S 450mah but accidentally left it on after ground testing until it drained completely. I wound up using one of my spares for the Eggfinder TRS which is a bit oversized as I tend to use it all day when flying.
 
Nice flight and video, glad to see you put it back together after the first attempt.
 
Jim,

That is very surprising and definitely not what I would have expected. What did you use to calculate whether it would separate or not

Andrew

An easy way to look at this is to do a simulation where you separate the stages and allow a little coast time before lighting the sustainer. Then, you look at the change in the acceleration of the rocket before and after stage separation. If the acceleration become less negative after separation (i.e., the sustainer doesn't want to slow down as fast as when the parts were together), then the parts will want to drag separate.

One flaw in this approach is that the sustainer does not have base drag at the moment of separation but does have it after separation. Therefore, it is possible that the parts might want to drag separate even if the acceleration of the sustainer is slightly more negative after separation. It might be possible to look at the base drag of the sustainer as a percentage of the total drag and estimate what the acceleration of the sustainer would be without base drag, and then do the comparison. It's interesting to look at varying the weights of the booster and sustainer, or the sustainer motor, and see where the crossover occurs.

Jim
 
An easy way to look at this is to do a simulation where you separate the stages and allow a little coast time before lighting the sustainer. Then, you look at the change in the acceleration of the rocket before and after stage separation. If the acceleration become less negative after separation (i.e., the sustainer doesn't want to slow down as fast as when the parts were together), then the parts will want to drag separate.

One flaw in this approach is that the sustainer does not have base drag at the moment of separation but does have it after separation. Therefore, it is possible that the parts might want to drag separate even if the acceleration of the sustainer is slightly more negative after separation. It might be possible to look at the base drag of the sustainer as a percentage of the total drag and estimate what the acceleration of the sustainer would be without base drag, and then do the comparison. It's interesting to look at varying the weights of the booster and sustainer, or the sustainer motor, and see where the crossover occurs.

Jim

That is an interesting approach and I will definitely try it out and play with the sim a bit. The one thing that I think would be difficult to simulate would be the force required to separate the stages especially dynamically inflight. I am thinking airframe spin, temperature, wind and angle of attack may all play a factor in the force required to separate the stages.
 
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