Estes motors

[kramrocket]

Hi all, just wondering if anyone has some recent data they've recorded from static tests of the D12 or C6 Estes motors they can share.

I need to check what's going on. My static tests back in the nineties showed similar results to the data the NAR and Estes own tests, but recent tests show otherwise .... longer duration (2.4 secs, but should have been about 1.7 secs) and less maximum thrust (20N but should have been about 30N), though a reasonable total impulse overall (about 17 Newton secs, but should have been 20Ns) has been recorded here.

 

Thanks for any help.

 

Mark K

[DavidF]

[kramrocket]

Thanks David, your graph aligns well with the data that both Estes and the NAR claim by their tests and also my tests back in the nineties.

 

The new D12's i've tested here in Australia burn for about 2.4 secs and peak at no more than 4.6 pounds ( 2.1 Kilograms) something is very wrong with

that.

 

I'm running a small class in model rocketry here and the students are getting confused with their results.

 

May I ask when your test motor was purchased? (batch number?)

 

We may have a counterfeit batch of motors (chinese) maybe?

 

Thanks for any advice.

 

Mark K

[DavidF]

Edited September 8, 2017 by DavidF

[DavidF]

[DavidF]

Sorry, my patience is wearing thin at my ability to stick pictures in a post, with text. This text is about the above posts. So, I was unable to determine the age of the motor used in Run 34. It was likely from 1997 or so.

 

The next two results above are from an opened package, manufactured in 2002? I assume this, because the numbers on the motor read A 07 02 07. I could be wrong. I tested them today. The impulse is less for both, compared to run 34, but not by a huge amount. Admittedly, they are both more similar to each other than to the original test result posted. That's to be expected, I think? I haven't looked into this a lot, but performance variations from batch to batch of black powder products does seem to be considerable, sometimes. I hope this helps in some way.

Edited September 8, 2017 by DavidF

[kramrocket]

Thanks for your work David,

 

I'ts great that you took the time and expense to test your motors for my benefit, it's very much appreciated !!!.

 

It seems my latest motors are different than yours, your year 2002 motors comply reasonably well with the Estes and NAR data but my 2017 ones don't.

 

Mark

 

 

[stix]

Thanks for your work David,

 

I'ts great that you took the time and expense to test your motors for my benefit . . .

 

 

Not just for your benefit kram, but also for the benefit of everyone else.

 

Yep, also appreciate David's work and costs.

 

I guess the next question to be asked is: "Has anyone in the US or anywhere else, done some static tests using CURRENT Estes D12 motors".

 

As kram suggests, perhaps us Aussies are given the sh*t ones. It's not like it hasn't happened before.

[DavidF]

Hey, glad to share if I can. Plenty of folks share with me. I had no newer motors to test, I checked. I will pick up a pack of D-12s and check them out next time I go to the city. BTW, David Sleeter's first book "Building your own rocket motors" was written in 1983. He tested Estes D-12s as having about 2 pounds of steady thrust, and a 1.6 second burn time. He also said that every motor of theirs that he tested was described as having a peak thrust of 50% higher than what he found empirically. Of course, peak thrust on an end burner is really not a very useful number. It just seemed interesting to note.

[stix]

Hi David,

 

Thanks again for doing those tests.

 

Just a query. I've noticed that you have used the D12-3 which is all good, as it does/should show the same thrust profile as the D12-0.

 

Run No. 34 shows the fuel consumed as 1.34 ounces (approx. 28 grams) which makes sense because the standard fuel weight is around 25 grams - plus the delay charge would seem about right.

 

However, Runs no. 174 & 175 show the fuel consumed as 0.04 ounces - a little over 1 gram??

[justvisiting]

OK, it took a while for me to get this done! In the meantime, I have a new username, and I can't use my old one (DavidF) now, if I want to post something. Nobody's fault but mine.

Kramrocket, you are right about Estes D-12s being weak now, compared to before. I ordered these engines last year. They have now switched to only putting 2 engines in a package, and the retailer's pricing is now as if there were 4 or 5 in the package! The code on the motors is A072613.

Stix, maybe Aussie's AND Canadians get the sh*t ones. Or maybe they are all sh*t now. At least they are consistently weak

The guy to ask is Ian von Maltitz. I'm pretty sure he still runs the place. He can be contacted through American Fireworks News, since he writes articles for them.

I don't bother about the fuel consumed, according to the Acme. At such low weights, the accuracy is just not there. With the Estes motors, the number shown would also include the delay and the clay pressed in on top of it. Even if I weighed the motors before and after, the weight lost wouldn't be indicative of the propellant consumed.

I bought these just to test BTW. I can make 1lb endburners that beat the old (gooder) Estes motors

EDIT: There, I think I fixed it so the graphs can be seen properly. I don't know why Acme sensed the total burn time as much longer (5.25 sec.) on Run 177. As can be seen, it gives an unrealistic number for the mean thrust, when looking at all the other information. I've never seen that happen before, but I don't test a whole lot of end burners.

Edited April 23, 2018 by justvisiting

[stix]

Thanks David.

 

I can't click on the images - says I don't have permission? - possibly something to to do with your new account?

 

In any case, Thanks for doing those tests. What you've said and tested seems to confirm our results here in Aus. It's a shame because me and kramrocket (my brother) always used the Estes motors as a "gauge" to test the performance of our latest thrust meter contraption. I can't see the total impulse on those graphs so I hope that can be sorted.

 

And Yep, I have a standard sugar rocket motor that beats the pants off the D12, but it's nice to have another standard to compare with - but not any more.

[shockie]

Over the past 60 years the type and potency of the BP used by Estes for their model rocket engines has changed several times. In addition, during that time, they may have also modified the nozzle, both of these would result in different Thrust-Time curves.