E3M ~ 4.5" O motor project

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mannyskid

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Last time you guys saw me, I had CATO'd my last big motor at Aeronaut:

Musket Chops Thread

In the mean time, I played a small role in helping my friend Steve Heller get his optimized 98mm rocket built and off the ground. After an awesome flight at BALLS to 62k', I was motivated to get back on the horse and do another large project. For the past couple weeks, the knowledge of a launch with a 75k' waiver in Las Cruces, NM in early January that some close friends will be attending has been in the back of my mind. Last weekend when I went back to my parents house, while building my mom a new chicken coop, the wreckage of the CATO'd 5" motor was staring me in the face the whole time. It was then that I decided that I had to try another 'O' motor for this New Mexico launch. After some discussion with friends and a little time in the computer lab (while procrastinating for writing my aircraft structures beam code), I decided that this project would be based around a 6' length of 4"sch 40 DOM pipe (4.5"x4.026) or a standard 114mm motor.

The 0.24" wall on this pipe will give me a larger safety margin then the 0.1875" wall used on the CATO'd 5" motor, and will allow me to run higher pressure and a "hotter" formula. Initial simulation on this motor puts it at around a 30k Ns O8000. The following is a list of major problems with the 5" motor that CATO'd that will be addressed in this motor.

-Liner Issue
~The 5" motor used a 4.5" fiberglass tube as a liner. This was a problem as there was roughly 0.0625" of clearance between the liner and case. It is possible that the liner cracked when the motor came up to pressure. This time, I will use a MAC performance 98mm XX phenolic airframe as the liner. This tube has an OD of 4.026, exactly what the ID of the aluminum tube is so I will have to sand the OD to get a dead nuts fit.

-No Set Screws
~The 5" motor used 1/4-20 set screws instead of bolts or pins. The problem with set screws (and bolts) is that the effective loading area is only on the minor diameter of the screw, which is less than 3/16" for a 1/4" bolt. Also, with set screws there is even less loading area due to the divot used for the allen head. This motor will use 3/16" pins in a yet to be determined pattern.

-Sealing Problem
~The 5" motor use 1/8" Orings instead of the normal 3/6" Orings, this was done so that I could get an over all shorter nozzle, however I discovered that with the amount of compression that I had there was not enough of a seal to make me comfortable, this motor will use 3/16" Orings with more compression.

-Airframe Transitions
~The rocket the 5" motor was more rushed than I had hoped it would be. For the transitions I had simply wiped RTV silicone around the lip where the airframe transitioned. For this rocket, the fin can tube will be hand wrapped over a 4.5" OD PVC pipe, then glued directly to the casing (it is designed to be single use) and the lip will transition to the case via a homemade ablative and sanded smooth. The upper airframe will be omitted on this vehicle and the nose cone will be coupled directly to the case via the same method used on Sunday Silent (see link for optimized 98mm rocket above).

RasAero puts this combination at roughly 40-45k', not record breaking but if I can manage to get an O motor to stay together and break my current altitude record (42k' commercial, 24k' EX) in the process I will be very pleased.

Also, the name E3M stands for "Eggs Three Meat", don't ask about the meaning I would prefer to keep it an inside joke. ;)

Manny
 
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Las Cruces? Hmm I have a trip planned there in a couple weeks and never been to NM . May have to research & checkout the launch site!

Good luck with the project, really fun to watch people push the envelopes
 
Have you thought of using an EPDM liner? They work great and are easy to fabricate.

Edward
 
tell me more about this:

"....a launch with a 75k' waiver in Las Cruces, NM in early January...."

I will likely be in New Mexico a good part of January - might be cool to include this launch to my itinerary.

s6
 
Las Cruces? Hmm I have a trip planned there in a couple weeks and never been to NM . May have to research & checkout the launch site!

Good luck with the project, really fun to watch people push the envelopes



tell me more about this:

"....a launch with a 75k' waiver in Las Cruces, NM in early January...."

I will likely be in New Mexico a good part of January - might be cool to include this launch to my itinerary.

s6



Sorry to break the bad news to you guys, but per the agreement with the BLM for this launch site we are limited to the number of attendees and we want only those directly involved with the 6 projects that will be flying.
 
I got the nose cone today:

ImageUploadedByRocketry Forum1447186851.270983.jpg

Also, I will be mixing the propellant for this motor this weekend. 13kg of a formula from Ryan Sebastian (butalane) that was used on the "Honey Badger" line of rockets and has been modified to be a bit slower.

Current estimates put it at a 26kNs O5500.

I will post an update with a picture of the cured grains early next week.
 
Sorry to break the bad news to you guys, but per the agreement with the BLM for this launch site we are limited to the number of attendees and we want only those directly involved with the 6 projects that will be flying.

Yeah, I was invited and then uninvited lol.
 
Sorry to break the bad news to you guys, but per the agreement with the BLM for this launch site we are limited to the number of attendees and we want only those directly involved with the 6 projects that will be flying.


hmmmmm........"directly involved" seems like it is pretty open to interpretation, no?

s6
 
hmmmmm........"directly involved" seems like it is pretty open to interpretation, no?

s6

I am pretty sure the BLM permit is restricted by the number of people, directly involved or not. Manny and others "directly involved" are probably at or very close to that number.
 
hmmmmm........"directly involved" seems like it is pretty open to interpretation, no?

s6

I am pretty sure the BLM permit is restricted by the number of people, directly involved or not. Manny and others "directly involved" are probably at or very close to that number.


Yes, per the BLM permit, we are restricted to 10 people at the launch site. We have 6 people flying rockets, 5 EX motors (3x O's, an N and an M) and one commercial N. The remaining slots are reserved for the waiver holder and other launch support personnel, so we have already reached the 10 person limit.
 
Yes, per the BLM permit, we are restricted to 10 people at the launch site. We have 6 people flying rockets, 5 EX motors (3x O's, an N and an M) and one commercial N. The remaining slots are reserved for the waiver holder and other launch support personnel, so we have already reached the 10 person limit.

Understood.

Of course, BLM land IS public land, and the public IS allowed to pretty much go where they want to, and if a person just happened to know where and when certain things were going to occur, and they just happened to be around at the time - in no way "a part of" the launch itself of course, well then.......
No one would have a reason, or indeed the right, to keep them from just watching stuff that goes on, would they?

How would such a person happen upon the information about where/when? There are plenty of (discreet) ways.

and Woody sings, "this land is your land, this land is my land, from California, to the .........."

s6 (who does have a pm box, if anyone cares to send him one)




a
 
Understood.

Of course, BLM land IS public land, and the public IS allowed to pretty much go where they want to, and if a person just happened to know where and when certain things were going to occur, and they just happened to be around at the time - in no way "a part of" the launch itself of course, well then.......
No one would have a reason, or indeed the right, to keep them from just watching stuff that goes on, would they?

How would such a person happen upon the information about where/when? There are plenty of (discreet) ways.

and Woody sings, "this land is your land, this land is my land, from California, to the .........."

s6 (who does have a pm box, if anyone cares to send him one)




a

Without getting into a jovial review of the constitution, being in a position of having to justify to the BLM how information was disseminated and having to explain who knows who, and how, isn't something I think anyone would want to sign themselves up for. Best case, it'll be an added stressor in an already highly stressful weekend. If there are other people using the land that weekend (which there won't be), we'll ask them to go elsewhere aside from our coordinates, and if for some ridiculous reason they refuse, we'll launch another day. There will be 10 people when we launch. That's what I can control.

We'll take video, promise.
 
I got my 4" XX phenolic airframe and 56" of XX coupler tube from MAC performance today. This will be used as the liner and casting tubes for this motor.

ImageUploadedByRocketry Forum1447435268.491524.jpg

ImageUploadedByRocketry Forum1447435280.711742.jpg

ImageUploadedByRocketry Forum1447435305.749349.jpg

The case stock should come today as well. The casting tubes were the important part as I'm flying MSP-DFW this evening in order for Steve (Prophecy) to intercept me on the way to mix propellant, and I kind of need the casting tubes to cast the propellant.

Now, I need to figure out how I'm going to fit these in my backpack to avoid having to pay a carry-on bag fee since I'm flying the worlds cheapest airline.
 
Bimodal AP blending, aka the dance of my people.

ImageUploadedByRocketry Forum1447602728.644450.jpg

Propellant ready to cast. I didn't take any pictures of the cast propellant since we worked from 9am yesterday to 3am this morning, and we're gearing up to do it all over again today.

ImageUploadedByRocketry Forum1447602938.850233.jpg
 
Bimodal AP blending, aka the dance of my people.

View attachment 276176

Propellant ready to cast. I didn't take any pictures of the cast propellant since we worked from 9am yesterday to 3am this morning, and we're gearing up to do it all over again today.

View attachment 276177

You're an animal, Manny! Keep up the good work!

Interesting that you guys pre-blend the various AP sizes...unless working with a (purchased) mixture, I've never done that. Again, interesting.

-Eric-
 
Following along, best of luck Manny.
 
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Following along, best of luck Manny.



My guess (hopefully) is that they are measured individually into the bucket then premixed before being introduced into the mixture.

Precisely. It's interesting, I'm surprised this has caused conjecture on the forum and elsewhere, with the common misconception being that we mixed a random amount of properly ratioed trimodal oxidizer, shook it, and measured out the amount of total AP from that bucket, with the resultant particle distribution in the propellant being essentially random due to a rudimentary and brief mixing (shaking) process.

When you're using a 31kg x 0.1g resolution scale, it's much easier, less dusty, and frankly more precise to measure each particle size, by calculated amount, into a common container, lightly pre-blend, and then add into the mixture as one as opposed to doing it individually in three containers, leaving residual dust in each container, lengthening the amount of work done under a strong ammonia smell, and leaving more containers to clean.

Using unknown particle ratios would be a horrible idea on even the most basic hobby motor, so I can't fathom why anyone would do it on an aggressive, large motor. Surprised that a few folks seem to have drawn this conclusion from the bucket picture, hopefully this clears it up.
 
Precisely. It's interesting, I'm surprised this has caused conjecture on the forum and elsewhere, with the common misconception being that we mixed a random amount of properly ratioed trimodal oxidizer, shook it, and measured out the amount of total AP from that bucket, with the resultant particle distribution in the propellant being essentially random due to a rudimentary and brief mixing (shaking) process.

When you're using a 31kg x 0.1g resolution scale, it's much easier, less dusty, and frankly more precise to measure each particle size, by calculated amount, into a common container, lightly pre-blend, and then add into the mixture as one as opposed to doing it individually in three containers, leaving residual dust in each container, lengthening the amount of work done under a strong ammonia smell, and leaving more containers to clean.

Using unknown particle ratios would be a horrible idea on even the most basic hobby motor, so I can't fathom why anyone would do it on an aggressive, large motor. Surprised that a few folks seem to have drawn this conclusion from the bucket picture, hopefully this clears it up.

I took Burner's reply as more rhetorical and a bit tongue and cheek rather than a serious question.
 
I took Burner's reply as more rhetorical and a bit tongue and cheek rather than a serious question.

Haha, James is an old friend of mine and taught me everything I know about building high performance projects with hand tools among many other things. Just posing a generic reply as I've gotten a a few inquiries all asking the same thing since that pic was posted.
 
Haha, James is an old friend of mine and taught me everything I know about building high performance projects with hand tools among many other things. Just posing a generic reply as I've gotten a a few inquiries all asking the same thing since that pic was posted.

...and as a follow-up to my post, I literally just never considered measuring out the bi/tri AP sizes and pre-mixing. Based upon scale capacity and the fact that I have them individually separated, I've never done so. Didn't strike me as good or bad, just different and something I'd never thought of. Different cheetahs to skin....or something like that!:)
 
Finally found my way back to TRF after a long hiatus. Glad to see the project is coming along.

The launch site near Las Cruces is no longer a club launch site due to the new restrictions imposed by the BLM. I negotiated personally, not as part of the club, for occasional launches under the "casual use" clause. Any organized group must go through a lengthy and expensive permit process without a guaranteed outcome. The area is now part of the "Organ Mountains - Desert Peaks National Monument", a Presidential declaration covering 1/4 of our county's land area without a vote by Congress or local residents. Everyone is uncertain about future restrictions, including the ranchers who lease the land, hikers, geocachers, horseback riders, etc, that "casually" use the land. My own property is enclosed by the park borders.

Nobody that was invited by me was ever uninvited. Anyone is welcome to make use of the waiver and my arrangements with the BLM. There are no specific dates set aside, just ask a few weeks ahead. The limit is 10 people and 5 cars per gathering. A violation is $100K per person in attendance for an organized event without a permit (this is in the Federal Regulations, not just made up by the local office). Things may change in the future, but this is the best I could do. For now, priority goes to student outreach projects that need the extra area. Other special projects that can't wait for BALLS will be considered as long as there aren't any other conflicts.
 
Using unknown particle ratios would be a horrible idea on even the most basic hobby motor, so I can't fathom why anyone would do it on an aggressive, large motor.

I do it all the time. I don't actually know the exact particle ratio after I dump it out of the ball mill, nor do I screen it. The important thing is that I do it the same every time. Besides, unless you screen it yourself or examine it under a microscope, you are just trusting your supplier.
 
Haha, James is an old friend of mine and taught me everything I know about building high performance projects with hand tools among many other things. Just posing a generic reply as I've gotten a a few inquiries all asking the same thing since that pic was posted.

Yep, I was trying to clear up the confusion...i only edited it my reply shortly after because I thought maybe I misunderstood the question, guess I didn't after all. I do the same thing for my multi-modal mixtures.
 
Feeling a bit unsure whether or not the grains that I made a few weeks ago for this project would be safe to fly, last weekend I decided to make a 75/6000 load of this formula and test fly it this weekend in my Ultimate Darkstar. Here is a video of the flight:

[YOUTUBE]xsJ6TsRZkRc[/YOUTUBE]
 
First time all of the parts for E3M are in one spot, had to do a "dry fit". Liner still has to be cut about 4".

ImageUploadedByRocketry Forum1450555525.815896.jpg
 
I have been slaving away at this project the past couple days, fins will be attached tomorrow. They will be bonded directly to the case via 3M 8115 epoxy.

ImageUploadedByRocketry Forum1450735650.450799.jpgImageUploadedByRocketry Forum1450735719.992927.jpg

My mom's chickens approve...

ImageUploadedByRocketry Forum1450735761.560430.jpg
 
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