Dear Decision-Makers in Penrose: More Plugged Rocket Engines, Please!

[AtlPhilip]

The answer to that question is self-evident, given the presumed (and likely) requirements and advice from the insurance companies and attorneys, ie "do it my way if you want legal and insurance protection."

If we're just making up "facts" to support an unsubstantiated opinion, I submit that it is self-evident that the insurance company actually begged them to allow it and the NAR denied their request based on a letter from mh9162013.

And since this thread has devolved into circular reasoning and outright fiction, I'm going to go do something actually useful and pour some epoxy in the top of a 6 grain L motor.

 

[jmasterj]

TRA doesn't allow BP motors, modified or unmodified. But they do support modification of all motors they allow.

Might want to check out the unified safety code - that's not accurate.

 

[AtlPhilip]

Might want to check out the unified safety code - that's not accurate.

What is inaccurate?

 

[BABAR]

Thank you for clarifying that we are discussing your opinion and not actually "what's ok and what's not ok from a legal/insurance coverage perspective." Now that we have dispensed with that facade...

It is my opinion that such a limitation is pointless from an practical or engineering perspective. It is also my opinion that NAR should modify it's safety code to permit such activity, and that doing so would keep such activities covered by insurance.


TRA doesn't allow BP motors, modified or unmodified. But they do support modification of all motors they allow.

And what is the basis for your belief? The MSRC. Which brings us back to "who wrote the MRSC?" A: The NAR

Hmm, I'm confused. Someone corrected me earlier (when I mistakenly PRESUMED they looked at low power with some level of condescension) and said Tripoli encourages all levels of rocketry, including low power, and had a signficant proportion of low power flights at SOME of their launches. Would be hard to do that if Black Powder motors were not allowed.

I think the original questions was the title of the post, asking Estes to make more plugged motors. Regarding whether NAR should change the rule or not, my suspicion is that the only people NAR is going to listen to is their attorneys and insurance provider. But doesn't hurt to ask?

 

[Art Upton]

Tripoli allows Certified BP motors, not modified or research BP motors.

 

[jmasterj]

What is inaccurate?

Both sentences. Certified BP motors are allowed. Modification of certified motors is allowed per manufacturer guidelines if the motor is to remain certified. Anything else would fall into EX, where there are limits on what fuels and oxidizers can be used. As I said, you should read the safety code and the EX rules.

 

[AtlPhilip]

As has been hit above, I would bet my motor stash that that deference is to satisfy insurers.

TRA manages to obtain insurance for research/Ex. They even call their flagship launch "Large and Dangerous". If they can insure a large homemade motor, NAR can surely find coverage for a C6-0 with a dribble of epoxy added as a fwd closure.

 

[4regt4]

Actually it is pretty strong.

There is a fellow who used to come to WAC launches at Sixty Acres who insisted on flying a Mean Machine on a D12-0. It never failed to get the 'chute out, even though it was REALLY early.

If you want to see how strong it is, fly a -0 motor (like E12-0) in a Rocketarium Vortico. It makes a very loud "pow" and forcibly pushes the rocket downward.

Hans.

 

[BABAR]

If you want to see how strong it is, fly a -0 motor (like E12-0) in a Rocketarium Vortico. It makes a very loud "pow" and forcibly pushes the rocket downward.

Hans.

Soooooooo , basically the same as the old Quest black powder motors?

 

[mh9162013]

If they can insure a large homemade motor, NAR can surely find coverage for a C6-0 with a dribble of epoxy added as a fwd closure.

You're comparing experimental motors to off-the-shelf motors, so the insurable risk will be different. One reason being the type of individual using an experiment motor (legally) will likely have far more experience and skill in rocketry than some random individual buying a pack of engines off the store shelf at their local Hobby Lobby.

As for finding coverage for plugged BP engines, I'm sure that any additional coverage will cost the NAR (and in turn, its members) more money due to higher premiums. And this is assuming there's an insurance company even willing to underwrite the added risk.

 

[BEC]

If you want to see how strong it is, fly a -0 motor (like E12-0) in a Rocketarium Vortico. It makes a very loud "pow" and forcibly pushes the rocket downward.

Hans.

Oh yes. We have a couple of club regulars who love their Vorticos (mine is still in the bag) in both the 24 and 29mm versions. They are great illustrations of just how forceful that burn-through of the propellant is. Or even a Snitch or the upper stage of a Frick-N-Frack — all show this very clearly, and fairly near the ground where you can see it.

That said it still surprises me that one can get the 'chute out of a Mean Machine that way.

 

[Art Upton]

Oh yes. We have a couple of club regulars who love their Vorticos (mine is still in the bag) in both the 24 and 29mm versions. They are great illustrations of just how forceful that burn-through of the propellant is. Or even a Snitch or the upper stage of a Frick-N-Frack — all show this very clearly, and fairly near the ground where you can see it.

That said it still surprises me that one can get the 'chute out of a Mean Machine that way.

A10-0s were used in a SuperRoc Competition at a Naram; and someone complained even though they were deploying the chutes better then the delayed motors that were deploying too low to the ground or on the ground.

In a 13mm Superoc that tail on the A10 would actually be the delay.

You would have to ask Bob K for more info on that.

 

[cls]

I'm really not in favor of allowing just anyone to modify Estes BP motors!!! By definition they don't know what they are doing. If they knew what they were doing, they'd be TRA L2 at least.

So no, don't ask NAR and Estes to change NFPA 1122. It's that way for reasons.

 

[BEC]

You would have to ask Bob K for more info on that.

I'm sure he would tell me more than I'd ever want to know if I asked him...

 

[jmasterj]

TRA manages to obtain insurance for research/Ex. They even call their flagship launch "Large and Dangerous". If they can insure a large homemade motor, NAR can surely find coverage for a C6-0 with a dribble of epoxy added as a fwd closure.

TRA won't insure that epoxied BP motor either, sadly.

 

[Alan15578]

A10-0s were used in a SuperRoc Competition at a Naram; and someone complained even though they were deploying the chutes better then the delayed motors that were deploying too low to the ground or on the ground.

I flew the 4 Oz. 21 foot "Trusswerk I" at NARAM-22 with an unaltered Estes A10-0t. I used an external streamer and the A10 was just to release the end. It was DQ'd for a list of invalid and dubious reasons. Essentially it was a technological surprise that the contest jury reacted poorly to. Stupidroc rules were quickly changed to impose a length limit. There was also high wind at NARAM-12 that contributed to many deployments too low to the ground.

In a 13mm Superoc that tail on the A10 would actually be the delay.

Exactly, but not just 13mm Superocs.

You would have to ask Bob K for more info on that.

Bob saw a technology demonstrator ,externally flown streamer, that I successfully flew in a regional, and he flew a long 5 Oz. tuber at NARAM-22 (that I call Noodle Roc) with an A10-0, which then had a manufactures max recommended lift of weight of 5 Oz. Bob could tell you more, but he does not participate on TRF.

Many dead horses, brutally whipped.

 

[BEC]

Today's A10s certainly won't lift 5 ounces. The are notably less energetic, especially on the long low-thrust tail of the burn, than old examples that would have been extant 30-odd years ago. I am actually a little worried about flying a two-stage B Pay Alt model at NARAM-65 for that reason. Hopefully pistoning the thing will work. It seemed to be OK at NARAM-61, which is the last time I flew B Pay Alt.

I have flown both old and new motors in the little Checkmate and have altitude and acceleration data to show the difference. But it would take a little time to locate a specific comparative example.

This is a tangent to Ken's original intent for this thread, however..... surprise, surprise.

 

[brockrwood]

The answer to that question is self-evident, given the presumed (and likely) requirements and advice from the insurance companies and attorneys, ie "do it my way if you want legal and insurance protection."

If there is this much discussion about why it should be permissible to put epoxy into -0 motors to “plug” them, I think one of my initial questions is answered. There IS a market for plugged motors other than the A10-PT. Estes, the faithful have spoken. They want A8-P’s, B4-P’s, B6-P’s, C5-P’s, C6-P’s, D12-P’s and whatever other -P motors you wish to make!

 

[Cape Byron]

Good points.

I guess the best options would be, in order, the dog barf hack, a plug built into the motor mount assembly, and a Safety Check person who doesn’t really care about this particular issue when nobody’s looking (the last one being a distant third).

A plug in a purpose built motor mount seems like an excellent, and simple, idea.

 

[dhbarr]

If I was going to fly plugged -0's, I'd probably:
- put in a plywood bulkhead directly above the MMT, with another smaller disc that goes just inside the MMT
- reinforce the outside of the MMT from below the bulkhead about a motor diameter or so.
- insert a tight-fitting removable plug that fills the empty casing volume
- be certain of my motor retention

I'm not entirely certain it wouldn't work for short delays as well. I would consider the plugs to be a consumable after a couple of uses.

 

[bad_idea]

There IS a market for plugged motors other than the A10-PT. Estes, the faithful have spoken. They want A8-P’s, B4-P’s, B6-P’s, C5-P’s, C6-P’s, D12-P’s and whatever other -P motors you wish to make!

There was a D11-P. slightly milder thrust curve than the D12, burns slightly longer, and has slightly higher impulse. AMW still has them for $20/pack of three. Edit to add: Performance Hobbies lists them for $17.50 for 3-pack.

Interestingly, as of a decade ago, Estes were willing to do a run of them for a 1,500 motor order. It was already certified by that point of course.

 

[Dugway]

- insert a tight-fitting removable plug that fills the empty casing volume

I've been thinking about this as well. Something 3D printed that would tightly thread into the top of a C6-0 motor casing to "plug" it. It could be completely single use. How would this be any different from the approved dog barf + tape?

 

[jmasterj]

I've been thinking about this as well. Something 3D printed that would tightly thread into the top of a C6-0 motor casing to "plug" it. It could be completely single use. How would this be any different from the approved dog barf + tape?

It probably wouldn't, since it's not gluing anything to the motor.

 

[Art Upton]

There was a D11-P. slightly milder thrust curve than the D12, burns slightly longer, and has slightly higher impulse. AMW still has them for $20/pack of three. Edit to add: Performance Hobbies lists them for $17.50 for 3-pack.

Interestingly, as of a decade ago, Estes were willing to do a run of them for a 1,500 motor order. It was already certified by that point of course.

Those where used in their R/C Rocket Gliders, they had two models. I have one built and never flown on my garage wall.

 

[Back_at_it]

I'm not here to tell you to break any rules and certainly don't encourage you to do this at a club or a anywhere around people but I have plugged my own motors. Back in the day I had a Estes Deep Space Transport, It only flew a couple of hundred feet on the available C5-3's and the C6-3 was barely fast enough to be stable off the rod.

I added a pair of motor mounts to the outer tubes so I could add a couple of booster motors. I first tried A8-0 and they worked but they blew the motor out the rear regardless of how much tape I used. On the next flight I soaked some wadding in wood glue and stuffed that in the end of the A8-0's and it worked perfectly. I figured plugging the motor was safer than hot motors fall on the grass.

That rocket flew a bunch of times with home made plugged A8's and B6's. Each time it had a C6-5 in the main tube. I'd love to build another one of those knowing what I do today.

If I had to do it again, I think I'd just mix up some epoxy and pour it into the end of the motor.

Again. If you try this, do so away from people and property.

 

[Daddyisabar]

I would surmise the D11 P just didn't have a big enough market to be profitable. At a higher cost and lower production runs they would just sit on store shelves. Too easy for the modifying cheapskates and scumbags to simply expoxy or dog barf plug (or other plugging methods of red lables,) not even mentioning the highly uncouth scrape out mods of green lables.

The good ole black lable D11 P had a nice, thick, poopy clay plug on top. Maybe harder to manufacture and requiring a good deal of space on top of propellant section. Just look at all the BP motor manufacturing- Quality Control issues these days. Pop, there goes another E9 nozzel. Bang, there goes another 24mm CATO. Splat, there goes another lack of ejection with a fully in tact clay cap on a green lable. Buy up all those remaining D11 Ps!

Maybe.too much of a PITA to clay plug a 18mm B6 0 or not enough space in a C6 0. Lest we dare to question what goes on behind the secure doors of Certified motor production. Black powder motor production/modification is very dangerous explosives work and not for the meddling of the general public.

So we are left with teaming masses of flyers needing easily clusterable and plugged motors for lord knows what kind of flying abominations. Just a little dab of 5 min epoxy on top of that C6 0, give it a couple of good twirls, clean up any exterior spillage and place vertically to cure. Oh the horror, insurance issues and dark arts purveyance. Whoosh! There goes another three cluster, modified Estes SR 71 with widely spaced pods. YIKES!

 

[dpower]

I'd certainly go for a C6-P, it'd be easier than the epoxy plug I use. Sometimes I'll kick a motor, but I prefer to plug them when possible. I once tried friction fitting 1/2" lengths of dowel into B6-0 motors, for a non-glue method, but they shot out the top and did a little damage to the plugged motor mounts - and there isn't enough room in a C6-0 to do that anyhow. I occasionally plug B6-0, never anything smaller, since the A10-PT is available. FWIW, up until 1971, Estes sold a plugged B motor, referred to as B4-0(P).

 

[brockrwood]

I'd certainly go for a C6-P, it'd be easier than the epoxy plug I use. Sometimes I'll kick a motor, but I prefer to plug them when possible. I once tried friction fitting 1/2" lengths of dowel into B6-0 motors, for a non-glue method, but they shot out the top and did a little damage to the plugged motor mounts - and there isn't enough room in a C6-0 to do that anyhow. I occasionally plug B6-0, never anything smaller, since the A10-PT is available. FWIW, up until 1971, Estes sold a plugged B motor, referred to as B4-0(P).

A B4-0P? Time for Estes to go through the old filing cabinets and dig out the specs and production steps!

 

[brockrwood]

I would surmise the D11 P just didn't have a big enough market to be profitable. At a higher cost and lower production runs they would just sit on store shelves. Too easy for the modifying cheapskates and scumbags to simply expoxy or dog barf plug (or other plugging methods of red lables,) not even mentioning the highly uncouth scrape out mods of green lables.

The good ole black lable D11 P had a nice, thick, poopy clay plug on top. Maybe harder to manufacture and requiring a good deal of space on top of propellant section. Just look at all the BP motor manufacturing- Quality Control issues these days. Pop, there goes another E9 nozzel. Bang, there goes another 24mm CATO. Splat, there goes another lack of ejection with a fully in tact clay cap on a green lable. Buy up all those remaining D11 Ps!

Maybe.too much of a PITA to clay plug a 18mm B6 0 or not enough space in a C6 0. Lest we dare to question what goes on behind the secure doors of Certified motor production. Black powder motor production/modification is very dangerous explosives work and not for the meddling of the general public.

So we are left with teaming masses of flyers needing easily clusterable and plugged motors for lord knows what kind of flying abominations. Just a little dab of 5 min epoxy on top of that C6 0, give it a couple of good twirls, clean up any exterior spillage and place vertically to cure. Oh the horror, insurance issues and dark arts purveyance. Whoosh! There goes another three cluster, modified Estes SR 71 with widely spaced pods. YIKES!

No widely spaced pods. Only pods close to the centerline. That’s what my scratch builds look like. Kind of like boosters on the Delta IV Heavy (all 18mm tubes) or the Atlas V with booster pods (13 mm booster pods). Gotta’ keep it safe here!

 

[Daddyisabar]

No widely spaced pods. Only pods close to the centerline. That’s what my scratch builds look like. Kind of like boosters on the Delta IV Heavy (all 18mm tubes) or the Atlas V with booster pods (13 mm booster pods). Gotta’ keep it safe here!

But widely spaced pods are so cool and work well with epoxy plugged booster motors! Give into the Dark Side.