Higher-impulse variations of Estes BP motors

[SolarYellow]

Just noodling while I make a snack. Thinking about the difference between a B6 and a C6, where they are essentially the same thrust curve, except the B6 shuts down at 0.8 seconds and the C6 keeps going to about 2.0 seconds.

What if that sustain burn could be extended to the full length of the case for a -0 booster motor? No delay grain, no ejection charge, no cap. Just fill that little tube all the way up with BP. Would be a heck of a neat Dsomething-0. And a 24x70 motor would become an Esomething-0. A 24x95 motor would probably still be an Esomething-0.

Or, make it plugged, but with the plug all the way at the top of the motor. A little less impulse, but compatible with electronic deployment that's becoming more popular as the price comes down.

Of course, Estes will never do these cool things, because their profitability depends on very large numbers - got to keep Mable humming along at the maximum yield. But it would still be cool.

Makes me appreciate AT more and more.

 

[cerving]

Estes used to make a few plugged motors, an A10-PT for the dragsters and I think they had a couple 24mm motors for use in clusters too. It probably wasn't worth their while to keep making the 24mm motors. You can "legally" plug a -0 motor by stuffing some dog barf in the well and taping it closed. You can also plug one by filling the well with epoxy... but the jury is out on whether that is a "legal" thing to do or not (unless you fly it as a Tripoli EX motor).

 

[Pinetree]

I like Estes because I suppose it reminds me of my youth, there's a lot to be said for a company that's been around longer than I have.

Usually when I go to the Hobby store, there's some kid looking at the kits and motors that's probably young enough that his dad had to drive him to the store.. and I think that that's probably the customer they've after.. which is great.

Looking through my box of motors, I definitely have more Estes than other brands, but I will agree there's something about sending a Big Daddy up on an AT E20-7 that you don't get from Estes.

But more important than all of that... what kind of snack, and why aren't there any pictures?

 

[rharshberger]

Estes used to make a few plugged motors, an A10-PT for the dragsters and I think they had a couple 24mm motors for use in clusters too. It probably wasn't worth their while to keep making the 24mm motors. You can "legally" plug a -0 motor by stuffing some dog barf in the well and taping it closed. You can also plug one by filling the well with epoxy... but the jury is out on whether that is a "legal" thing to do or not (unless you fly it as a Tripoli EX motor).

BP motors are not legal for TRA Research just like Sucrose sugar motors.

 

[Alan15578]

Just noodling while I make a snack. Thinking about the difference between a B6 and a C6, where they are essentially the same thrust curve, except the B6 shuts down at 0.8 seconds and the C6 keeps going to about 2.0 seconds.

What if that sustain burn could be extended to the full length of the case for a -0 booster motor? No delay grain, no ejection charge, no cap. Just fill that little tube all the way up with BP. Would be a heck of a neat Dsomething-0. And a 24x70 motor would become an Esomething-0. A 24x95 motor would probably still be an Esomething-0.

Or, make it plugged, but with the plug all the way at the top of the motor. A little less impulse, but compatible with electronic deployment that's becoming more popular as the price comes down.

Of course, Estes will never do these cool things, because their profitability depends on very large numbers - got to keep Mable humming along at the maximum yield. But it would still be cool.

Makes me appreciate AT more and more.

It seems like you want a Cox D8-0.

 

[SolarYellow]

I'm that guy who cleaned out all of Rocketry Works' A10-PT motors when they went 50-off. I like them for clusters because the big initial push helps get a heavy cluster rocket off the rod/rail. Even more importantly, they are very light due to the lack of delay grain and ejection charge, so they diminish the stability problem inherent to clusters where the motor mass is concentrated as far in the back of the rocket as possible.

Snack was a banana/apple/protein smoothie I make every afternoon/evening.

There are no Cox motors on Thrustcurve. I'm not familiar with them, but that sounds kinda like what I'm thinking.

 

[rharshberger]

I'm that guy who cleaned out all of Rocketry Works' A10-PT motors when they went 50-off. I like them for clusters because the big initial push helps get a heavy cluster rocket off the rod/rail. Even more importantly, they are very light due to the lack of delay grain and ejection charge, so they diminish the stability problem inherent to clusters where the motor mass is concentrated as far in the back of the rocket as possible.

Snack was a banana/apple/protein smoothie I make every afternoon/evening.

There are no Cox motors on Thrustcurve. I'm not familiar with them, but that sounds kinda like what I'm thinking.

Cox motors have been out of production since early in my rocketry adventures...thrustcurve what was that in those days.

 

[SolarYellow]

Cox motors have been out of production since early in my rocketry adventures...thrustcurve what was that in those days.

Yeah, I know that. I'm not really personally interested in vintage stuff that can't be cloned, so I haven't geeked out on Cox rockets. Do kinda wish I'd had a few Tee-Dees back in the day and hung onto them. I still think they're cool.

 

[rharshberger]

Yeah, I know that. I'm not really personally interested in vintage stuff that can't be cloned, so I haven't geeked out on Cox rockets. Do kinda wish I'd had a few Tee-Dees back in the day and hung onto them. I still think they're cool.

I had a TD powered free flight saucer back in the day

 

[Alan15578]

Yeah, I know that. I'm not really personally interested in vintage stuff that can't be cloned, so I haven't geeked out on Cox rockets. Do kinda wish I'd had a few Tee-Dees back in the day and hung onto them. I still think they're cool.

The Cox Babe Bee motors had awesome fun power from cheap reed valve motors, but yes, if you wanted marginally more power from $4X rotary valve motors, you could buy that TD.

I was not suggesting that you fly vintage Cox D8-0 motors. I was illustrating the proven capability of producing an 11.5 N-s BP motor in a casing size normally used by a 9 N-s C6 Motor.

Thumbs up for A10-PT, but I am not sure that they are reliable enough for clustering.

 

[prfesser]

A sorbitol or other TRA-approved sugar motor could be made into such a booster motor, *if* the burn rate could be increased significantly. The sustaining thrust is the motor operating as a pure endburner (all Estes motors are "cored endburners"). Propellant burn rate would have to be at least a half-inch per second---twice that would be better---in order for sustaining thrust to be high enough to be useful. There are lots of catalysts for sugar motors but a fair bit of trial and error would be needed.

Downside: as a research motor the flight would have to be 200 feet away.

 

[bad_idea]

You can also plug one by filling the well with epoxy... but the jury is out on whether that is a "legal" thing to do or not

Unfortunately the jury is in. Someone here on TRF made a point of asking both NAR and TRA leadership the question not long ago, and having been asked directly, neither could continue to ignore it as a gray area. Both said no.

 

[cls]

A10-PTs have been super reliable for me. Always light, never CATOed.

I have several packs of old D11-P and E9-P motors. Those always worked reliability (even the E9s). Estes made them for RBRGs like T25 Centurion.

I saved them for a few "someday" projects, as side boosters, etc. although I have one or 2 T25s in boxes, unbuilt. Gotta start clearing out these "someday but actually never " projects.

 

[Scott_650]

I'm that guy who cleaned out all of Rocketry Works' A10-PT motors when they went 50-off.

I had a couple packs in my cart just to have them for some unknown future project then took them out before I clicked the pay button - so you’re welcome!

But now I definitely have non-buyers remorse

 

[cerving]

Unfortunately the jury is in. Someone here on TRF made a point of asking both NAR and TRA leadership the question not long ago, and having been asked directly, neither could continue to ignore it as a gray area. Both said no.

Thanks, I had not seen that. It's too bad... basically, you're not really modifying the motor's performance or function in any way, but it is what it is. Apparently, stuffing dog barf in the cavity and taping it over IS legal... so I guess that's what I'll continue to do.

 

[bad_idea]

Thanks, I had not seen that. It's too bad... basically, you're not really modifying the motor's performance or function in any way, but it is what it is. Apparently, stuffing dog barf in the cavity and taping it over IS legal... so I guess that's what I'll continue to do.

I'm starting to build clusters to vent out the back of the body tube when flying on black powder. Have also tested plugging motors with both wadding and with a dowel and o-ring. Haven't had great success with either method yet, including badly damaging two rockets. Need to do more ground testing before I try either again in flight.

 

[SolarYellow]

Quoting myself to save typing, as it's become relevant here.

SolarYellow said:
I'm sure I recently read some safety code-type content that said something about not permanently gluing anything to the motor, but I did a search and can't find in in NAR, TRA or NFPA 1122. Anyone know what I was reading?

Discussed elsewhere, but I figure I'll land the plane. Pretty sure that what I'd recently read was the text below, which is the rule book for competition, but not specifically part of any safety code. So my post quoted above was clearly confused and/or confusing:

NATIONAL ASSOCIATION OF ROCKETRY
UNITED STATES MODEL ROCKET SPORTING CODE
4 MODEL ROCKET MOTOR STANDARDS
4.4 Alterations
A model rocket motor must not be altered in any manner that changes its dimensions and/or its performance characteristics. No material may be permanently affixed to the motor.

This explains why "flying motor" records are excluded for NAR, but are allowed in Tripoli.

As far as glue vs. tape, although there are tapes that are effectively permanent, most tapes, especially masking or foil tape that is generally used for retaining motors, are reasonably considered temporary, whereas most glues will sufficiently damage a paper motor case when removed that they are reasonably considered permanent. I suppose if someone wanted to push on it, a rubber cement that would peel off without damaging the surface of the paper might squeak by. Or the idea in the OP of this thread could be executed with peelable rubber cement and likely be reasonably defensible.

For non-competition use, it would be subject to interpretation whether permanently affixing something to the motor constituted tampering. There doesn't seem to be a red line there, especially if the performance characteristics are not changed, but a discussion could be had around whether that changed the dimensions, at least if the Sporting Code is held to provide relevant context for interpreting the safety code. Ultimately, because the safety code only includes the language "tamper with," there is flexibility that makes the final call subject to the judgement of a particular RSO. Or jury, if a plaintiff's attorney happens to be included in a discussion much lengthier than anyone would like.

Turning a -0 booster motor into a -P plugged motor would be changing its performance characteristics. The powers that be seem to be OK with doing so in a reversible manner with tape (perhaps that is just the "installation" of the motor in the rocket that is designed around the performance characteristics of the motor), but not OK with doing so in a permanent manner with epoxy or other glue (which alters the design of the motor itself).

Non-permanent plugging to keep -0 motors from spitting fire out the front has been demonstrated to be sufficiently easy and effective as to be completely practical. Having gotten my head around the methods, I see no reason to complain about the status quo today.

Also, I second the suggestion of 1/4-inch wide masking tape making tape thrust rings easier to install, although it ironically costs a little more than the cheap 3/4 inch wide stuff, which can be easily trimmed flush with the end of the motor once applied.

One last thing: Obviously, putting epoxy or CA on/around the clay nozzle to prevent it blowing out and CATOing is not changing overall dimensions or performance characteristics, so I would judge is in compliance with the safety code, but would not expect it to be permitted in NAR competition.

Just to add, I guess epoxying nozzles for reliability might get past an RSO in competition, but I should think would be protestable and the protest should be upheld. Competition isn't always easy, and rolling the dice on motor quality is part of the luck factor that applies to a whole bunch of other aspects of flying. Of course, that's just, like, my opinion, man.

 

[SolarYellow]

Thanks, I had not seen that. It's too bad... basically, you're not really modifying the motor's performance or function in any way, but it is what it is. Apparently, stuffing dog barf in the cavity and taping it over IS legal... so I guess that's what I'll continue to do.

Somewhere, I saw data where someone documented that the thrust of a plugged -0 motor continues longer than the thrust of a non-plugged -0 motor, so it technically is modifying the function for increased impulse.

 

[BEC]

Somewhere, I saw data where someone documented that the thrust of a plugged -0 motor continues longer than the thrust of a non-plugged -0 motor, so it technically is modifying the function for increased impulse.

It makes sense that it would. In a normal booster motor a good bit of hot gas and probably propellant goes out the top when the chamber pressure breaks the forward wall of the combustion chamber. This is clearly visible when flying booster motors in saucer-type models.

 

[bad_idea]

I figure a blocked-off motor with an ejection charge should have the most bonus impulse, but my attempts at shallow, removable plugs for the C5-3 - which I plugged not for bonus impulse but to use in a mixed cluster - resulted in considerable carnage.

 

[SolarYellow]

Yeah, I'd expect the ejection charge to either turn the plug into a projectile or CATO the motor in a case rupture.

 

[bad_idea]

Yeah, I'd expect the ejection charge to either turn the plug into a projectile or CATO the motor in a case rupture.

Some old competition flyers - who were epoxying their motors - swear the ejection charge gave them a nice kick, so I don't think a CATO is likely. At that point the only powder left in the motor is the ejection charge. Might blow out a nozzle, but that's just more impulse.

Epoxy is probably now a no-go however. Testing with plugs squeezed tightly between a motor and a bulkhead, I may or may not have gotten a bit of extra kick, but I did most definitely explode my strap-on test boosters. I'll try again at some point, but on the ground.

 

[ghughes1138]

Just noodling while I make a snack. Thinking about the difference between a B6 and a C6, where they are essentially the same thrust curve, except the B6 shuts down at 0.8 seconds and the C6 keeps going to about 2.0 seconds.

What if that sustain burn could be extended to the full length of the case for a -0 booster motor? No delay grain, no ejection charge, no cap. Just fill that little tube all the way up with BP. Would be a heck of a neat Dsomething-0. And a 24x70 motor would become an Esomething-0. A 24x95 motor would probably still be an Esomething-0.

Or, make it plugged, but with the plug all the way at the top of the motor. A little less impulse, but compatible with electronic deployment that's becoming more popular as the price comes down.

Of course, Estes will never do these cool things, because their profitability depends on very large numbers - got to keep Mable humming along at the maximum yield. But it would still be cool.

Makes me appreciate AT more and more.

Don't forget that since BP is usually compression molded into the case, there will always be an unfllled gap at the top of the case unless you are willing to cut away the excess case after loading.

At the 1980 WSMC, the US team had some engines custom made by Estes, including some as fully loaded as possible by a Mable type machine. The 24x70 engines tested out at 22N-sec IIRC.

gary

 

[MJ D]

There is no problem stuffing a little extra BP in the motor casing for a ghierh total impulse, it's easy to do if you own the Mabel machine and want to experiment. But is it a mass market product worth making in the thousands, or just a neat thing that model rocketeers think about..? And it would require all the certification to go with it. There's the rub. NAR rocketeers are but a wee subset of the market.

 

[Daddyisabar]

Traditional black powder is too explosive to fill up the empty space in a red lable booster motor for extra thrust. BP motors contain three types of "Black Powder." The first is a propellant grain which is a modified whistle mix, a super ancient Chinese secret formula used by a pryrotechinican back in the late 50's named Vern in Denver. The second delay grain is a super corporatized secret smoke bomb mix. The third is Traditional black powder for the ejection charge. All this, along with the super secret formula "poopy clay" nozzle and cap needs to be highly compressed using a super secret load and pressing machine, utilizing paper case compression along with nozzle-ignition point pentals. NOT FOR UNLICENSED NEOPHYTES!

Black powder is an Explosive! Do you have a magazine and explosives permit? Do you have a ball mill and a press with a lexan shield? Are you regularly inspected by the ATF and Sheriff's department? Do you think ricing is only done in Chinese restaurants? Black powder rocket motors are certified for your protection. NO BP MOTOR MODIFICATIONS!

Dark Side users will epoxy D12 and E12 0s closed. At launch they will say "Golly, that red lable motor had a little extra thrust!" They will show you the all the propellant burned clean away from the clear epoxy plug. Like a window you can see the light through the expoy window all the way to the nozzle. STAY AWAY FROM THESE SITHY SCUM! THEY WILL LEAD YOU DOWN THE WRONG PATH! A WRETCHED HIVE OF SCUM AND VILLAINY, YOU MUST BE CAUTIOUS.

Watch out for the pyros too. They blow up things in the air and have no concept of recovery and reusability. Building BP motors on their tailgates...YIKES! Bang bang bang with mallets, my inner rocket RSO is seeking the nearest Bunker.

COMMERCIAL, CERTIFIED BLACK POWDER MOTORS TODAY.

COMMERCIAL, CERTIFIED BLACK POWDER MOTORS TOMMOROW.

COMMERCIAL, CERTIFIED BLACK POWDER MOTORS FOREVER!

 

[MJ D]

Nobody suggested that, please read it again. And thanks for all the non-information. What I said is that the motors can be filled with more propellant when they are made (hence the reference to a Mabel, do you know what that is?), and I speak from direct hands-on experience.

You are totally out to lunch on the black powder comments. The propellant is plain BP, as is the ejection charge. The delay is commercial black powder substitute.

Any other wisdom to share?