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Yeah, I agree it's a bit of a niche problem, but my comment is just that I feel like it's a niche problem that doesn't need to exist. There are plenty of unused numbers around any of the designations, and I don't really get why there wouldn't be at least some effort put into avoiding collisions within the same manufacturer. As far as I'm aware, there's no reason the DMS and RMS H550's couldn't be called the H550 and H545 (or H555) - just like how several other DMS/RMS pairs are named slightly differently (I200/I205, H219/H242, J420/J425, K850/K990, L1090/L1000, and M1297/M1350 come to mind)
 
cautery said:
Just finished the RASP .eng files for the N4000W-PS using AeroTech's RAW data file.
One file with all 3676 samples, and one with only 61 samples.... No real reason to use the small one. Just made it to prove the point.

Sending them to Gary FIRST!
If he OKs, I will post here and at ThrustCurve.

I will get a proper XML formatted .rse file completed as soon as I can.

NOTE: These files are NOT from cert data. To my knowledge, the cert process has not been completed.
Click to expand...
The reason for using the file with 61 samples is that there are versions of the RASP algorithm floating around that can only handle a max of 64 data samples. In particular, one that I wrote/converted myself, many years ago. It will throw up with a buffer overflow if there are too many data points - which is very annoying, but I never got around to putting a 'graceful exit' in place for that event.
 
jmasterj said:
I wish all the motor manufacturers would combine the designation styles to include both total impulse and propellant type in the official designation. I prefer the current AT style if I have to pick one (I've never  not wanted to know the propellant), but the total impulse is a valuable piece of info as well, especially when combined with the average.

So we'd have a 61F67W and a 78F55C (I don't prefer the less-accurate designation just to match the old motor designation).
Click to expand...
CTI has the additional info and it can be nice to have without looking up the details in ThrustCurve.

I do see that the new F67C does NOT have 67N average thrust but only 56N.... that is a pretty big difference.
This is BAD and BREAKS the standardization on motor nomenclature.

We use motors Average Thurst destination to determine if the motor/rocket will have better than 3:1 or 5:1 TTW ratio.
The new F67C would be way under this ratio and can result in a BAD Flight (wind-cock)...
 
waltr said:
CTI has the additional info and it can be nice to have without looking up the details in ThrustCurve.
Click to expand...

Right, but they don't have the propellant type in their designations, which is a worse tradeoff for me. I would like to combine the best of both worlds, but as it stands I prefer AT's method.
 
msjohnso said:
The reason for using the file with 61 samples is that there are versions of the RASP algorithm floating around that can only handle a max of 64 data samples. In particular, one that I wrote/converted myself, many years ago. It will throw up with a buffer overflow if there are too many data points - which is very annoying, but I never got around to putting a 'graceful exit' in place for that event.
Click to expand...

Yes sir. I am well aware. :)

But, it is 2023 now. Any application that chokes on a 73 kb data file probably needs to be re-written or wished a fond farewell as it is allowed to drift off into history.

Remember, there is nothing stopping anyone from making their own file with whatever sample size they want. From the full file, the user gets to choose.

I am merely saying that you do not start with a data limit. You use all the available burns and all samples in each burn. Analyze for/eliminate outliers, and then "average" the burns by time.

Then, you can consider reducing the sample number.... but it should be a sample number and spacing that accurately reproduces the combined curve.

That curve tracer program will not work without a lot of work, which led to me the discovery that it takes less work to just make the file with all data.

What apps that are still being used choke? Let's name them. If there are critical apps, perhaps we can update them.

Be well! :)

(Edited for styling... original was from phone and adding styling from a phone ain't no fun! 👍 )
 
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Here's my free program that will take in any thrustcurve data format, and produce an ENG file. No data size limit, but it will allow selected the amount of filtering and the number of data points in the output. It's from 2006, written in Java, so it should still work on all platforms. But don't be too critical. :)

https://thrustgear.com/software.html

What's important when smoothing a thrust curve is to maintain the original total impulse. A thrust curve may vary quite a bit in the shape of the curve and the simulation won't change, but total impulse will affect the altitude. This is why NFPA 1122/5/7 only specifies a tolerance on total impulse and not on average thrust.

For velocity off the rod/rail, one should look at the thrust curve's initial 1/4 sec and not rely on the average thrust marked on the motor designation.

Now back to your regularly scheduled Aerotech thread!
 
jsdemar said:
Here's my free program that will take in any thrustcurve data format, and produce an ENG file. No data size limit, but it will allow selected the amount of filtering and the number of data points in the output. It's from 2006, written in Java, so it should still work on all platforms. But don't be too critical. :)

https://thrustgear.com/software.html

What's important when smoothing a thrust curve is to maintain the original total impulse. A thrust curve may vary quite a bit in the shape of the curve and the simulation won't change, but total impulse will affect the altitude. This is why NFPA 1122/5/7 only specifies a tolerance on total impulse and not on average thrust.

For velocity off the rod/rail, one should look at the thrust curve's initial 1/4 sec and not rely on the average thrust marked on the motor designation.

Now back to your regularly scheduled Aerotech thread!
Click to expand...

Thank you! That is a useful bit of kit! :)

I need to convert the other way right at the moment.... From an .eng file to an XML-based .rse file. Does a reliable tool exist for that?

I'd rather not reinvent the wheel if I can avoid it. I am just about to dive in to creating a reliable/fast process to take an .eng file or a RAW file(s) (with thrust time, weight, and CG channels) and convert it to a fully functional .rse file. If I can come up with a front end that allows the creation of the header with ALL of the file format's fields available, so much the better.

My goal is to be able to SKIP the .eng file altogether if I want.

At some point, I will try to reduce the process of analyzing and "distilling" raw data from multiple burns into a single thrust+ file to an automated/validated file.
 
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cautery said:
Thank you!

I need to convert the other way right at the moment.... From an .eng file to an XML-based .rse file. Does a reliable tool exist for that?

I'd rather not reinvent the wheel if I can avoid it. I am just about to dive in to creating a reliable/fast process to take an .eng file or a RAW file(s) (with thrust time, weight, and CG channels) and convert it to a fully functional .rse file. If I can come up with a front end that allows the creation of the header with ALL of the file format's fields available, so much the better.

My goal is to be able to SKIP the .eng file altogether if I want.

At some point, I will try to reduce the process of analyzing and "distilling" raw data from multiple burns into a single thrust+ file to an automated/validated file.
Click to expand...
I don't know of anything to convert ENG to RSE. Should be easy, even with a spreadsheet. But, we are way off topic for this thread.
 
Static testing a new 29mm x 9” long H14ST-P motor for setting ’H’ altitude records. The first firing was 258.3 N-sec, 46.6N peak thrust, 18.5 second burn time. The second firing produced 271.6 N-sec, 48.6 N peak thrust with an 18.1 second burn time. Because these motors operate at a relatively low average chamber pressure, small changes in chamber pressure can result in significant Isp and total impulse variations.

This is a notable increase in total impulse over the existing H13ST motor. I expect well-designed rockets to exceed 20,000 feet altitude with the H14ST.

IMG_1360.jpeg

IMG_1361.jpeg
IMG_1364.jpg

IMG_1363.jpeg
IMG_1367.jpg
IMG_1366.jpeg
IMG_1368.jpeg

View attachment H14ST-P.mov
 
Just to be sure, will the new motor be available without a thrust ring, like the H13? It makes it a lot easier to do extreme builds with fins bonded onto the case.

Edit: I'm an idiot and didn't look at the pictures in the post.

Edit: It's also really great to see you working on motors specifically designed to break records. Hope to see more in the future, maybe a high impulse long burn K.
 
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AlexBruccoleri said:
T

I agree! It is really fun to read the threads and see Aerotech responding with motors made for records.
Click to expand...
I'm hoping that they cook up something capable of breaking the K record. The 54mm endburners that have been teased so far don't have the impulse to challenge the K300. And with the pretty poor reliability of the K300, and long lead times from CTI on warranty replacements, I doubt many people will be willing to put in the work to build a rocket to break the K record, only to roll the dice on the motor working.
 
Neutronium95 said:
Just to be sure, will the new motor be available without a thrust ring, like the H13? It makes it a lot easier to do extreme builds with fins bonded onto the case.

Edit: I'm an idiot and didn't look at the pictures in the post.

Edit: It's also really great to see you working on motors specifically designed to break records. Hope to see more in the future, maybe a high impulse long burn K.
Click to expand...
The ones we made for cert have thrust rings. But yes, we can make them for sale without.
 
I did a long necked 29mm, snap ringed, Al case graphite nozzled motor years ago. First one was single use as the aft snap ring notch was gouged and wouldn't take a snap ring after first firing. The graphite nozzle was pretty beat up too and was single use. The next one survived a bit better as I used "gentler" propellant in it but I still considered it a single use case. That nozzle was pretty well beat up too but reusable. First fired 29 motor was in the "I" range according to Burnsim and second one was an "H".
The alleged "I" 29mm motor really put the rocket up a long ways and glad I had a tracker in it. The second motor was in the "H" range and I don't recommend anyone go higher than an "H" in the 29mm diameter. At least with long necked motors. Grains need to be stepped. (And Research guys know what I mean by that.)
The Prefect in the group I belonged to had three lathes and could turn whatever snap ring motor one would want. Just give'em the raw material! One lathe he kept for graphite nozzles only. He would move that lathe outside in the backyard as the graphite dust would go "everywhere". His shop was one stall in a 3 car garage. So easy to put small machines outside in the back with extension cords. Especially the graphite nozzle lathe!
I had him do some 29mm casings in 4044 Aluminum which is technically stronger than 2020 Al. Told me it was "witch" hard to cut on the lathe but got it done. Still have a couple of casings in the basement that are technically flyable (Ex or Research only yes). He turned some graphite nozzles for me too with the graphite I supplied him. Best I could find. Left the nozzle closed so I could bore the nozzle throat opening I needed for the propellant I wanted to run. Boy, I miss those old days at the rocket shop after he passed away.
Kurt
 
Neutronium95 said:
I'm hoping that they cook up something capable of breaking the K record. The 54mm endburners that have been teased so far don't have the impulse to challenge the K300. And with the pretty poor reliability of the K300, and long lead times from CTI on warranty replacements, I doubt many people will be willing to put in the work to build a rocket to break the K record, only to roll the dice on the motor working.
Click to expand...

The Aerotech K250 is only 46Ns below the K300 for total impulse
 
3stoogesrocketry said:
The Aerotech K250 is only 46Ns below the K300 for total impulse
Click to expand...
Where are you getting your numbers from? According to Thrustcurve the K250 has almost 200Ns less impulse than the K300. And as far as I know it's not readily available. CS Rocketry has two in stock, but I haven't seen any other vendors with them available recently.
 
That just means that more and more folks will hold off ordering anything that requires hazmat until/unless there's a major sale a la Wildman's BF sale.
 
That's unfortunate, but at least it isn't as painful as the price increases for motors have been. Well, except for the people who order a single hazmat H for a L1 cert. They'll be seeing the biggest price increase because of this.
 
I wonder if anybody has insight as to why. Is it actually that much more expensive for carriers to ship hazmat, or is that fee mainly to discourage sending a lot of hazmat boxes through the mail?
 
Neutronium95 said:
That's unfortunate, but at least it isn't as painful as the price increases for motors have been. Well, except for the people who order a single hazmat H for a L1 cert. They'll be seeing the biggest price increase because of this.
Click to expand...
Some of the H L1 motors, like the H128W, are not Hazmat.

I realize it involves grain size and other stuff that eludes me, but it's kind of crappy that an F for the 29/40-120 is Hazmat, and some of the HPR motors are not.

Hans.
 
4regt4 said:
it's kind of crappy that an F for the 29/40-120 is Hazmat, and some of the HPR motors are not.
Click to expand...
At least some are non-hazmat.... they could easily change the requirements that everything would require it regardless of type or size. I like that the manufacturs keep the current limits in mind, and work as many non-hazmat items into the catalog as they can.
 

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