AeroTech Open Thread

[Neutronium95]

I was wondering, on the M685W-PS, is it possible to replace the medusa nozzle with a normal single-throat nozzle like what was done for the M650?

It probably uses a single throat nozzle. A good number of the cutaway drawings of Aerotech motors are out of date, with many motors rhat uses to use Medusa nozzles changed to single throat nozzles, and some 98mm motors that have changed to the large nozzle still shown as using the smaller one.

 

[Wayco]

I was wondering, on the M685W-PS, is it possible to replace the medusa nozzle with a normal single-throat nozzle like what was done for the M650?

I think I've built them with both nozzles. The one I have built now has the medusa nozzle on it. That might help with the thrust vectoring problem I've had with a single nozzle though...
Offset cores seem to have that problem.

 

[Tom Flint]

I just bought a pack of D13 reloads with a 2019 date code. The package is marked D13-7, however the delay grains do not have a spacer and take up all the remaining space above the propellant grain inside the liner with the proper amount of propellant protruding from the aft end of the liner. From previous experience assembling these reloads, D13-7s have included a small spacer and a shorter delay grain, with D13-4s having a longer spacer and an even shorter delay grain. The only delay without a spacer is the 10 second delay which takes up the full remaining length of the liner. Would I be correct in saying that these reloads are actually D13-10s even though they are marked D13-7?

 

[Zertyme]

I think I've built them with both nozzles. The one I have built now has the medusa nozzle on it. That might help with the thrust vectoring problem I've had with a single nozzle though...
Offset cores seem to have that problem.

Thank you for your answer, can you elaborate on the "thrust vectoring problem"?

 

[Wayco]

@rfjustin made this comment on another thread:

Theoretically, that is true, but I have seen many a moon burner motors take "left hand turns" in minimum diameter vehicles, YMMV. May yours fly straight and true in KS calm...

I have also experienced several moonburners that lay over early in the flight.

You might want to read some comments here:
https://www.rocketryforum.com/threads/build-thread-for-this-years-airfest.172206/#post-2275070
I copied that quote from Justin's post #14, but several other fliers responded later in the thread.

 

[mikec]

Whether moonburners do that because of thrust vectoring or mass asymmetry is a topic of some debate, but it is certainly a common phenomenon.

But I've also seen it happen with the low-thrust AT endburners, which have no cores and no mass asymmetry, so it could also be mostly aerodynamic.

 

[firemanup]

Thank you for your answer, can you elaborate on the "thrust vectoring problem"?

1:10 into this video is my Extreme Wildman, 4” diameter bird with a 75mm motor mount on an M685, you will see the left turn people are talking about.

It’s never kicked like that with any other motor to include the M650 which is another moon burner. Have no idea why they do this or why mine did.

 

[3stoogesrocketry]

1:10 into this video is my Extreme Wildman, 4” diameter bird with a 75mm motor mount on an M685, you will see the left turn people are talking about.

It’s never kicked like that with any other motor to include the M650 which is another moon burner. Have no idea why they do this or why mine did.

This effect happens mainly on three fin rockets over four fin rockets . I would also like to mention the 12 to 15 mph gusts at ignition from the "right" of the rocket tipping it to the left and the resulting wobble up to a few hundred feet. But yes , overall , moon burners do tend to arch a lot more on flight then Bates style motors.

 

[firemanup]

This effect happens mainly on three fin rockets over four fin rockets . I would also like to mention the 12 to 15 mph gusts at ignition from the "right" of the rocket tipping it to the left and the resulting wobble up to a few hundred feet. But yes , overall , moon burners do tend to arch a lot more on flight then Bates style motors.

There was no 12-15 mph wind when it launched so I’m not sure where you get that, 3_FNC I understand vs 4_FNC rockets.

Winds were calm to 5 mph at launch as I remember also as recorded after flight. Launched after lunch.

 

[3stoogesrocketry]

There was no 12-15 mph wind when it launched so I’m not sure where you get that, 3_FNC I understand vs 4_FNC rockets.

Winds were calm to 5 mph at launch as I remember also as recorded after flight. Launched after lunch.

Just by looking at the corn dance , and the wind in the camera , I was guessing 12 to 15. The graph you shared shows the winds were above 5 mph all flying day pretty much, with average speeds up to 10 mph . I do apologize by my saying there was a 2 to 7 mph error in wind speed above the documented speeds you shared , it's been 10 years since I have flown at Argonia. But by your Video alone, also by your additional mention of the M650 didn't kick like that, the wind must have been a factor. I know the additional weight in front of the CP wouldn't do that.

 

[SolarYellow]

3_FNC I understand vs 4_FNC rockets.

Not to derail this thread, but that's new to me. I've been reading a lot of stuff and haven't come across it. Can you point me to a discussion?

 

[Rocketjunkie]

From my experience with moon and D grain motors. 3 caliber low speed stability flies straight. 1-1/2 caliber usually tips off toward the heavy side of the motor. (Can tell when installing the starter where the port is.)

 

[David_Stack]

Not to derail this thread, but that's new to me. I've been reading a lot of stuff and haven't come across it. Can you point me to a discussion?

How 'bout this one...

https://www.rocketryforum.com/threads/3-vs-4-fins-why-do-space-programs-prefer-4.62055/

 

[Rocket86]

Whether moonburners do that because of thrust vectoring or mass asymmetry is a topic of some debate, but it is certainly a common phenomenon.

But I've also seen it happen with the low-thrust AT endburners, which have no cores and no mass asymmetry, so it could also be mostly aerodynamic.

I'd love to know more about this, as I have plans for several M650 flights this year.

 

[firemanup]

Just by looking at the corn dance , and the wind in the camera , I was guessing 12 to 15. The graph you shared shows the winds were above 5 mph all flying day pretty much, with average speeds up to 10 mph . I do apologize by my saying there was a 2 to 7 mph error in wind speed above the documented speeds you shared , it's been 10 years since I have flown at Argonia. But by your Video alone, also by your additional mention of the M650 didn't kick like that, the wind must have been a factor. I know the additional weight in front of the CP wouldn't do that.

There is no corn in the video, watch the loading of the rocket as well where it’s dead calm, the graph shows winds were 5-7 mph all afternoon with much more time at 5 mph or less… not sure where you are still getting 10 mph.

Anyway, it was fairly calm and it was the only time I’ve experienced this, however I d have seen it happen multiple times.

 

[AeroTech]

I was wondering, on the M685W-PS, is it possible to replace the medusa nozzle with a normal single-throat nozzle like what was done for the M650?

It currently ships with a single-throat nozzle.

 

[AeroTech]

I just bought a pack of D13 reloads with a 2019 date code. The package is marked D13-7, however the delay grains do not have a spacer and take up all the remaining space above the propellant grain inside the liner with the proper amount of propellant protruding from the aft end of the liner. From previous experience assembling these reloads, D13-7s have included a small spacer and a shorter delay grain, with D13-4s having a longer spacer and an even shorter delay grain. The only delay without a spacer is the 10 second delay which takes up the full remaining length of the liner. Would I be correct in saying that these reloads are actually D13-10s even though they are marked D13-7?

The D13-7 and the D13-10 use the same length delay element, but different formulations (one slow, one regular).

 

[AeroTech]

New AeroTech/Quest ad running in the latest issues of Sport Rocketry and Hobby Merchandiser magazines.

 

[StreuB1]

Just by looking at the corn dance , and the wind in the camera , I was guessing 12 to 15. The graph you shared shows the winds were above 5 mph all flying day pretty much, with average speeds up to 10 mph . I do apologize by my saying there was a 2 to 7 mph error in wind speed above the documented speeds you shared , it's been 10 years since I have flown at Argonia. But by your Video alone, also by your additional mention of the M650 didn't kick like that, the wind must have been a factor. I know the additional weight in front of the CP wouldn't do that.

I flew off the pad next to Jason on that day. Flew my Ex Wildman to 14k on an M1297 and it flew dead straight, maybe a little to the south. Recovery was 1.3 miles to the south south east. Jason's went the opposite direction. There was little wind as well. The fields are milo.

 

[JeffBigg]

The D13-7 and the D13-10 use the same length delay element, but different formulations (one slow, one regular).

Is it possible to purchase the slower delay grains from RCS?

 

[A-ron]

New AeroTech/Quest ad running in the latest issues of Sport Rocketry and Hobby Merchandiser magazines.

Is that an upcoming kit model in the background? Can't wait to see that in the catalog...

SATURN V No. SA-506
SKILL LEVEL 11
LENGTH: 4,356" / 11,064 cm
DIA: 396" / 10,068 mm
RECOVERY: Tumble / Triple Nylon Parachutes
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AD6672300W-P (5)

MSRP $1,499,999,999.99

 

[Antares JS]

New AeroTech/Quest ad running in the latest issues of Sport Rocketry and Hobby Merchandiser magazines.
View attachment 567012

I printed this out and hung it in my cubicle at work.

 

[AeroTech]

Is it possible to purchase the slower delay grains from RCS?

We'll look into it.

 

[cragbot]

Are there any 98mm motors that are now shipping with the new large nozzle and therefore will no longer cross-load into CTI cases?

 

[tjsnakez]

Are there any 98mm motors that are now shipping with the new large nozzle and therefore will no longer cross-load into CTI cases?

Super Thunder loads, M2500T, and the 15360 loads all have the big nozzle. I think that’s it, but someone else can correct me if I’m wrong.

 

[AeroTech]

Super Thunder loads, M2500T, and the 15360 loads all have the big nozzle. I think that’s it, but someone else can correct me if I’m wrong.

Anything with a 1" throat or larger uses the big nozzle.

 

[Rocketjunkie]

Anything with a 1" throat or larger uses the big nozzle.

You will need a large hole closure previously used for Medusa nozzle reloads like the M750.

 

[JohnCoker]

Does anyone have the cert. doc. for the M1315W?

 

[jsdemar]

Does anyone have the cert. doc. for the M1315W?

 

[JohnCoker]

That's the manufacturer's insert. I meant the TMT certification letter.