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  #41  
Old 05-19-2013, 12:17 PM
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Earl Earl is offline
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Randy-

Do you recall the motors used in each stage? I assume 18mm BP of some type, but would be interested to know which, if you/she remembers.

I've done clustered five engine AP/BP single stage Saturn V flights and have long wanted to do a 'full up' Saturn V three stage flight......just never got it 'on the books' to try yet.


Thanks,

Earl
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  #42  
Old 05-19-2013, 04:28 PM
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Earl,

After a considerable development and research process was added to her own experiences, on the 100% successful launch she decided to go with:

1st stage 4 C6-0 & 1 D12-0
2nd stage 4 B4-2 & 1 B6-0
3rd stage 1 B4-4

The D12-0 & B6-0's were the core engines.

Her build, with photos and some narrative, is posted to the SEARS 572 website. http://www.sears572.com/supersaturnv.htm

Scroll the pages and follow the links at the bottom to see all 7 pages and the flight report to that date.

Randy
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  #43  
Old 05-20-2013, 03:16 AM
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Randy,

You indicate there was a 100% successful flight, but it is not covered in the flight report. Was Verna really able to gap stage 5 motors at once (1st to 2nd stage) and get all 5 second stage motors to ignite?

Steve
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  #44  
Old 05-20-2013, 09:09 AM
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Quote:
Originally Posted by Gus
I routinely gap stage 10.5 mm motors, both old Apogee motors and European motors. I also routinely gap stage Estes 13 mm motors. I have done a great deal of experimentation and high speed photography and here is what I have learned. (Doug, you and I discussed this in another thread ~4 years ago but I've experimented a lot since then so this info is slightly different)

Contrary to what G. Harry thought, staging, including gap staging has little to do with flying burning particles. In standard, non-gap staging, when motors are taped together booster burn-through results in a jet of flame entering the sustainer nozzle. Ignition depends on the nature of the flame jet and, more importantly, whether the force of the tape holding the motors together is enough to overcome the pressure buildup between the booster and sustainer long enough for the jet of flame to ignite the upper motor. Booster burn-through is an inconsistent process so the jet produced is quite variable.

The top of an Estes booster motor is simply the upper end of the pressed propellant slug. If you view it from above at ultra high speed burn through may occur in the middle, or closer to an edge. It may resemble a cross burning out from the middle of where the bars cross or be more like a widening circle. The variability of this burn through is completely random resulting in very different jets being produced. A booster that burns through closer to the edge will produce a flame jet which may not be centered near the sustainer nozzle opening. As the booster continues its burn-through the flame jet widens. If the tape can hold the motors together long enough for the flame jet to reach and enter the nozzle, then sustainer ignition will occur. In most cases taped together motors do a fine job and ignition occurs.

In gap staging, the tube between the booster and sustainer motors acts like fireworks Quick Match, propgating a ball of flame from booster to the sustainer almost instantaneously. A pressure wave of gas precedes the flame by milliseconds and, if not vented out the upper sides of the tube, will push the sustainer motor off the tube before ignition occurs. But what travels up and ignites the sustainer is not little burning embers, but a ball of flame that envelops the aft end of the sustainer motor causing it to ignite. Part of the flame ball also exits the vent holes. The ball of flame is long (in milliseconds) gone before noticeable flame begins exiting the sustainer nozzle.

This is why it is possible to reliably ignite gap staged European sustainer motors with VERY tiny nozzles, without any wick. Be aware, though, that European competition 10 mm booster motors are slightly different from Estes or old Apogee motors. Euro booster motors have a forward cap with a very tiny hole in the middle. When the booster motor burns through it is only a very tiny spurt of flame that exits the top end of the motor. Euro booster motors are designed to be augmented with a pinch of black powder on top that serves as the flame propgator for sustainer ignition.

The fact that gap staging depends on a moving ball of flame, rather than burning embers, allows you to do interesting things. You can actually gap stage around gentle corners. The sustainer motor does not have to be located in a straight line directly above the booster motor. My daughter's Little Joe 1A which she flew in Slovakia used this technique to have one of the 4 18mm booster motors located at their scale outward locations in the booster to ignite a 13 mm motor in the center of the base of the Mercury capsule (to simulate the escape motor). Photo of the LJ1A internals below. This system used standard Estes motors, no augmentation. Very reliable.

Final note. Wick is useful in a sustainer nozzle when you are trying to delay ignition by a second or so. The wick fills the sustainer nozzle preventing the ball of flame from directly igniting the sustainer. Instead, the wick ignites and then takes a second or so to ignite the sustainer. Useful if you are going for altitude, but it adds a whole extra failure mode and can be tricky.

Hope this info is useful,

Steve


Steve-

Interesting info. Sounds like the basis for a good tech article for Tom Beach to run in Sport Rocketry mag. I'm sure many would find it enlightening.

Earl
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  #45  
Old 05-20-2013, 09:58 AM
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I would tend to believe that top stage needed a B4-6 or B6-6 instead of a B4-4 !
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  #46  
Old 05-20-2013, 11:32 AM
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Gus,

She made 4 flights in all. Look back on this thread for the flights and dates. There were two attempts prior to the successful flight. The report on the SEARS website was about the April 2004 attempt and the build article was posted in May of 2004. The article there has not been updated since the original posting, 9 years ago.

Yes. Her 3rd flight was indeed 100% successful -- and came after the build article on November 17, 2004 - 6 months after the report that goes with the 7 page build was posted by SEARS president Greg Lane. In addition to Verna & I, the flight was witnessed by our club president at that time, Ron Witherspoon and my son.

Because the build article had already been posted to the SEARS 572 website, SR was not interested in an expanded article on her Saturns. There's a rule or something about any part of an article and previous postings but - Verna and her Saturns were featured in a brief article I did on another topic for SR that appeared April 2006 and it featured her and her Saturn V's .

Randy
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  #47  
Old 05-20-2013, 04:18 PM
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Randy,

I fly gap staged rockets more than almost anyone else I know. Simultaneously igniting 5 clustered gap-staged motors is a truly spectacular accomplishment! I've seen lots of multi-staged Saturn V's fly, but they all used electronics. Honestly, it never occurred to me that "going native" was possible.

I remember reading about Verna's Saturn a long time ago, long before I started gap-staging, so I wouldn't have truly understood how amazing it was.

I'm particularly intrigued that she got the D12 and C6's to work in harmony. The C6s actually burn slightly longer than the D12 so I would have thought the central motor in the second stage would have lit before the outboards. I also would have thought the likelihood of 1st and second stage torquing and preventing separation would have been really great.

Can you tell us what the failure modes were on the first two flights?

Again, thanks for sharing this. You just really expanded my envelope of what is possible.

I love this hobby.

Steve
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  #48  
Old 05-20-2013, 07:10 PM
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Steve,

Back up just a bit to post 40 of this thread where I typed up some of her notes; for some detail on all 4 flights.

Obviously you've got some good experience from your flights, as your last post on flight characteristics are very close to what we saw on her flights. The engine burn through times are miliseconds apart for the boosters but there is a small difference. On the first flight they were obvious, not as much so on the 3 that followed. There was mild torquing on all 4 but not enough to spoil the flights.

The thing I found the most interesting was what she took away from each attempt as to why things went the way they did and how she decided to adjust the next attempt. I think it was mainly the difference in how women think and the way men think. We often came to the same conclusions but differed on how to adjust. Her rocket/her choice.

Part of her adjustment was to use engines with the largest nozzles in the 2nd & 3rd stage, hence her selection and visual observations of what she was holding at the time. What we found VERY interesting in our motor selection and research was that there can be a big difference in diameter between nozzles of the same designation. Was it a screw up at the factory? We don't know but when they were used, they performed the same. Most lilkely every old timer here will say "It's not possible" but I'm telling you we saw it and in actual use.

I do not recall the exact engine so just for an example, say you had 5-6 packs of B6-0's. Upon inspection, you see all engines in each pack are the same, but when compared to another pack from another batch, the nozzles of pack #2 are easily larger in diameter, at least on the exterior surface. They look and perform identical in every way but one pack seems to have at least a 50% larger opening. I even took a photo and posted it for comment someplace, maybe RMR when it was still fucntional, I don't remember, definately not YORF or TRF. Almost had to be RMR/ABMR.

Maybe Jerry can shed some light on how to get the same thrust profile on 2 different engine nozzles.

Again, the torque factor was nominal but there was a definate change in angle after staging. The flights that were not successful mainly came down to simply missing a core motor all 3 times.

Verna would tell you the one that worked had the largest nozzles she could use, double the tape where they mate (about 1/2" wide by 1.5" long) 4 places spaced equally around the bt. (Lots of venting going on too) But she also said that when everything is perfectly built and the conditions are optimal there is still one major factor in being successful and that is LUCK!

Once I reminded her of what Bear Bryant and Knute Rockney used to say: "Luck is when preparedness, meets opportunity, so it tales your best effort and then a little help from God, Karma or whatever you happen to believe in. In this case she said she had some help from CHAD. ; )

With all said and done she feels that even in the best case senario it's still a 50/50 shot but when it works, it's truly amazing and satisfying.

Oh, one last thing, perhaps what sets her accomplishment apart from all the others, is that she didn't use electronics. She decided before she broke open the box that she wanted to do it old school.

Randy
www.vernarockets.com
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  #49  
Old 05-20-2013, 08:29 PM
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Looking at thread title "Significant events in clustering" and keep thinking that Gunnery St. Highway might have a different take on the mental image created.
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  #50  
Old 05-21-2013, 10:59 AM
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Gy.Sgt. R. Lee Ermey would most likely be of the same opinion as Gunny Highway and he is a REAL Gy. Sgt.
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, if you have to ask, you probably aren't
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