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  #11  
Old 06-15-2020, 02:44 PM
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Quote:
Originally Posted by BEC
Well, serious or not, this experimenter doesn't have a test stand (though I have thought about rigging something a few times).

Certainly agree with your last point. We need a TARDIS or some other way to time travel to even attempt to answer THAT question.

I'm satisfied that there is no clear "the old stuff is obviously better" indication from this, which is really what I set out to find out.


I agree, and you did a great job of that and I appreciate it. I tried to do a bunch of two stage tests with my daughter for a science fair projects and we got only a fraction done compared to what you accomplished.

I donít want to discourage you from posting more, itís neat to see what the old stuff does. I recently flew three Bs from 1996 which performed great. I am just happy if an old motor doesnít cato.
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  #12  
Old 06-15-2020, 02:51 PM
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Originally Posted by 5x7
I am just happy if an old motor doesnít cato.

Funny you should mention that. I was out yesterday trying out the mini rail and the new C5-3s and had an A10-0T from 1996 CATO in the first stage of my current Checkmate. This is the second CATO this poor model has experienced in only seven flights. The other A10-0T that CATO'd in this model was made in 2019(!!). But I have had another of these old ones let go like that.

That said, in general I've had no issues with Estes motors all the way back to the early 1970s.
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  #13  
Old 06-15-2020, 02:55 PM
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We do know that the black powder itself was once more potent. Our esteemed Estes folks have talked about the formulation and volume needed back then vs volume needed now to attain the same total impulse. As long as they stayed on top of the changes in BP and tweaked the volume (I doubt they fooled with nozzle tweaks), they would stay in the ballpark in performance over the decades.

If a weaker formulation was compensated with greater volume thrown into the casings and no nozzle changes were made, we could end up with a weaker max thrust but total impulse very similar. That would probably give us minimal altitude variation on light rockets. It would explain decades of seat-of-the-pants performance testing where we noticed C6-5's of the distant past doing better with heavier rockets than today, while your tests proved that total impulse is likely very close to motors of decades gone by.

Speculation, of course.
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  #14  
Old 06-15-2020, 03:06 PM
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Yes, that came straight from folks at Estes, and one of the reason they said that longer delays available in the past canít be done anymore. ( I think specially the A3-6T).

Many questions could be answered by test stand data. There is TON of test stand data. Hundreds if not thousands of tests over many years. I want to do an R&D report on delays, so I asked for it and NAR S&T refuses to publish it or provide it.
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  #15  
Old 06-15-2020, 03:12 PM
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Quote:
Originally Posted by BEC
Funny you should mention that. I was out yesterday trying out the mini rail and the new C5-3s and had an A10-0T from 1996 CATO in the first stage of my current Checkmate. This is the second CATO this poor model has experienced in only seven flights. The other A10-0T that CATO'd in this model was made in 2019(!!). But I have had another of these old ones let go like that.

That said, in general I've had no issues with Estes motors all the way back to the early 1970s.

To the best of my knowledge, I've only had 2 C5-3's from the bad batch (I got smart and didn't fly the 3rd one), some D12's and a couple A10's CATO. That doesn't count the old Estes E15 because I think i only ever had one flight that didn't cato! The A10's were roman candles. The C5's were immediate rocket dissassembers without moving off the pad at all. The D12's and E15's disassembled about 20 ft off the pad to the best of my recollection. One of my D12's was an immediate disassembly on the pad.
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  #16  
Old 06-15-2020, 03:23 PM
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Roman candle is a pretty good description of an A10-0T CATO. In every case I've had they've managed to light the sustainer in the process, so the rest of the flight actually proceeded pretty normally. In yesterday's case, the difference in apogee was only ~20% from a normal A10-0T to A3-4T flight and the one that had a CATO in the first stage.
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  #17  
Old 06-15-2020, 03:52 PM
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Quote:
Originally Posted by BEC
Roman candle is a pretty good description of an A10-0T CATO. In every case I've had they've managed to light the sustainer in the process, so the rest of the flight actually proceeded pretty normally. In yesterday's case, the difference in apogee was only ~20% from a normal A10-0T to A3-4T flight and the one that had a CATO in the first stage.

I've got a good photo of an A10 spinning in the air and burning from both ends after it chucked itself out of my Super Big Bertha. I parallel staged the D12 with a pair of A10's to help burn up a bunch of them I got on a Walmart clearance years ago. The other A10 is still burning straight and true along side the D12 in the pic.
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  #18  
Old 06-15-2020, 06:41 PM
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I dropped Bernard's data into JMP, and wanted to share some One-way plots. This is treating age in years as a categorical variable. The Anova diamond pool the error across groups. If they overlap, they aren't significantly (to a statistician) different. If you're not familiar with a Tukey-Kramer plot, if the circles don't intersect by a certain angle, they aren't sig different - circle size is determined by error and replicates, more reps, smaller circle. I added the std dev bars to the delay plot.
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  #19  
Old 06-15-2020, 07:12 PM
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Quote:
Originally Posted by tbzep
We do know that the black powder itself was once more potent. Our esteemed Estes folks have talked about the formulation and volume needed back then vs volume needed now to attain the same total impulse. As long as they stayed on top of the changes in BP and tweaked the volume (I doubt they fooled with nozzle tweaks), they would stay in the ballpark in performance over the decades.

If a weaker formulation was compensated with greater volume thrown into the casings and no nozzle changes were made, we could end up with a weaker max thrust but total impulse very similar. That would probably give us minimal altitude variation on light rockets. It would explain decades of seat-of-the-pants performance testing where we noticed C6-5's of the distant past doing better with heavier rockets than today, while your tests proved that total impulse is likely very close to motors of decades gone by.

Speculation, of course.

I seem to recall what changed was the quality of the charcoal.
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  #20  
Old 06-15-2020, 07:16 PM
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Scott,
I recall the same; quality and type of charcoal have been going downhill.
Takes more volume of BP now to get the same total impulse due to this.
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