6mm Reload composites?;dream or a possibility? [Archive]

ScrapDaddy

3rd March 2010, 03:36 AM

I know this sound totally 50 years from now but while I was posting on another thread here I got into a short discusion with someone about the possiblitys of 6mm realoads I have caught news that ***** ***** ********* is develeoping them (it's not displayable since I don't know it firsthand but if you do want to know the manufacturer just pm me; but if you are even viewing this thread there is an exclent chance that you already know) so I was wondering if anyone has gotten any news on the possiblity that some crazy manufacturer has any plans for 6mm reload composites?
Pros:we can finally lift payloads in micromaxxes with FYI is now an offical NAR challange
We can finnally break some clouds with these tiny birds.....
Cons: High loss possiblity, all of you micromaxxers know the feeling, OMG where did my micromaxx go?
Manufacturing them; how on earth would you make somthing like a reload casing in a 6mm size
Assebling them; you have all had the feeling "Whoops I got grease
on the o-rings!!"
Igniting them; don't quote me on this but the fattest q2 iv seen was about 3mm across; although I don't se why I couldn't just use nicrome wire.

Ok so people is this possible or fantsy? Please vote and post :D

ben_ullman

3rd March 2010, 04:10 AM

Green Monkey Aerospaces name can be displayed on TRF, not sure why people have issues with that.

6mm reloads are not that hard. reloads would be a pain to assemble but not that bad.

Ben

powderburner

3rd March 2010, 04:27 AM

6mm reloads might not be too bad if you are really into experimenting, and designing/building your own motors, but I just cannot see how something like this could ever be successful on a retail level

People who really like to do it can build their own kit cars, but the percentage of people who do so does not even register on national automobile sales

A good indicator for this motor category might be the 10mm "contest" motors that used to be available a few years back. Go into the NAR records and find out how many were ever used in competition. Go ahead and triple or quadruple that number, to allow for some testing and development of competitive designs. Yes, this approach to calculating the number of motors used cuts out the people who bought a few for fun, or just to say they did, or to stash 'em in a collection. I'll bet the number of 10mm motors actually flown for competition isn't even recognizeable against 300 million BP motors made by our Penrose friends.

And our hobby has probably shrunk since then---probably half as many serious low-power rocketry nuts who would even be interested? (You ain't gonna sell any $5 MMX motors at W-Mart, if you could even make them that cheap)

A 6mm composite reloadable would definitely be fun as a learning experience, as a technology push, or for just plain showing off, but I just don't believe there is any kind of retail market that would make it worth while

kullas

3rd March 2010, 05:21 AM

Hmm i have some extra sugar made up i may have to heat it up and stick some in a spent case to see what it does.

The EGE

3rd March 2010, 05:29 AM

As powderburner pointed out, there's just not a commercial market for them; I doubt GMA would bother.

There's also some practical problems.

1) APCP (composite propellant) burns at roughly 1/2" per second if I recall correctly. A motor with 4mm wide grains (and that's probably larger than it would actually be) and a 2mm core would thus have a burn time of under 1/10 second; that would be practically useless. With an endburner, even with Warp-9, cross-sectional area is so small that you're looking at thrust of about 0.8 N maximum, and since such a motor would be at very low pressure (with an inferior nozzle), the thrust would be even lower; perhaps 0.2N - not even able to lift itself.

2) You won't be able to fit much of an igniter in. Bare nichrome won't ignite APCP, and pretty much any other igniter won't fit inside even with a minimum of pyrogen.

3) Hardware would be really really expensive to machine in such a tiny size at low production volumes. And it'd be so thin that it'd be easy to break.

4) Micromaxx rockets are hard to spot at the altitude they currently achieve. At 2 or 4 times that, they'd be impossible to find.

5) APCP would be very difficult to cast at that grain size. The grains themselves would be too fragile to ship. You would have to pour them yourself and immediately load the motor.

6) In order to fit any pyrogen-based igniter, the nozzle would have to be very wide, and that would prevent it from being very efficient.

7) You're talking absolutely miniature components - the delay grain would be about the size of a pencil lead. No one wants a reload they have to load with tweezers...

8) Cost... APCP is more expensive than BP, and the internal components would add a lot of cost. No one wants cost-per-flight several times higher than comparable-impulse motors, not to mention the casing cost.

9) There's not much point. There's not gonna be much substantial weight savings, and these rockets are so tiny that drag doesn't come much into play.

10) The delays used in composite motors tend to be pretty long... The forward closure would be as long as the case.

So, dimes to dollars says you're never gonna see a commercial 6mm reload. If you can make one (safely... that means waiting till you're a bit older), then I'll be pretty impressed.

Rocketjunkie

3rd March 2010, 05:57 AM

I've looked into Micro-Maxx size composites, single use. The propellant would be cast directly into the phenolic case. They would be full 1/4A in power. Core burner would be about a 1/4A3-3 and the end burner would be about a 1/4A.3-3. (1/4 sec burn on the core burner and 2 sec on the end burner. Getting an igniter into the .017" diameter nozzle of the end burner has stumped me so far...

MarkII

3rd March 2010, 07:37 AM

The concept of a 6mm reloadable motor is absurd. Enormous technical challenges would have to be overcome to create something that would do very little. No rational person would make the significant financial investment that would be needed for such a project. And even if one were to be developed, would anyone seriously pay $20-$30 for just the case and closures? The entire reason for developing a reloadable motor is to lower the costs of composite propellant motors by making the most expensive parts of the motor reusable. There would be no cost advantage to producing a tiny reloadable motor, since the cases for single use versions of them would be very inexpensive. It would make no economic sense to try to save a few cents by reusing the case. And without any economic advantage, the entire rationale for purchasing a reloadable system disappears. If any 6mm composite motor were ever developed, it would be in the single use format. It would still be very tough to create one, but from a technical standpoint, it wouldn't be completely outside the realm of possibility, I suppose. As various people have said, igniting it would perhaps be the biggest challenge, though. But I'm not so sure even that would be impossible, just extremely difficult. As for fitting enough propellant into the case to yield significant impulse, nothing says that you would have to be limited the Micromaxx's length of 1"; you could certainly make it longer. There would be absolutely no demand for such a motor, though. What niche would it fill?

A much more relevant project would be to develop a black powder Micromaxx motor with a longer delay, and possibly with a longer burn time. The current really short delay (< 1 second) was appropriate for the first generation LPBs, but for the current generation of lightweight paper and balsa micros, the very abbreviated coast time really limits their performance. As for visibility, yes, some micro rockets made with minimum diameter tubing can disappear from view in as little as 150 feet, but many lightweight, high performance models are being produced with BT-3 and even BT-4 tubing, which is much easier to track. (But one should note that the current 1/8A altitude record is something like 90 meters, or close to 300 feet. At least a couple of observers were able to track a competition model to that height, so it tracking micros beyond 200 feet can be done.)

13mm single use composite motors (again, not reloadables) would be less of a technical challenge, but even then, where would the market be? Would anyone really want to spend something like $5-$6 for a 13mm C? And, returning to the first topic above, who would pay $4 for a 6mm A? Is there such a demand for the Aerotech RMS 18/20 motor that people are clamoring for something smaller? You can purchase 13mm hardware from GMA or else make your own, but how many people are actually doing that? Especially since you need to be a member of Tripoli with at least Level 2 certification in order to have sanction to cook up your own propellants and cast your own motors.

MarkII

Micromeister

3rd March 2010, 02:11 PM

Could not agree more or put it better then Marks last post! Great post Mark! Absurd is the optimal word.

Micros are just fine with the output power we have now. not to mention they are in keeping with my main goal of lowest possible price per launch.

Their is absolutely nothing that is done in model rocketry that hasn't or can't currently be done with micros with the possible exception of mile high flights... but Altitude is NOT the only reason for flying in the first place.
RC, on board electronics, Staging, clusters and yes ScrapDaddy we already have a Payload designed for our micors that boost just fine on our current BP motors.
I neither need or want AP involved with my Micro models. It's simple not a concern.
By the way, There have already been several successful 6mm AP and Sugar propellant motors experimented with over the past 4 years. But as many have already mentioned the overwelming tech glitches and Igniter Placement limitations have more or less directed those of us looking at them to conclude it's just not worth the hastle.

I'm in favor of looking at longer delay times for our current MMX-II motors i've personally had models tracked and closed over 300feet on the OLD MMX-I motors. While they had a posted 1 sec delay their actual average delay was over 1.07s allowing considerably more coast time then our current .857s delay motors. I've been experimenting with 3 and 4 sec delay upper stage times but they still require added mass or supercaps to power and ignite the upper stage or ejection.
Prehaps a bit longer motor could be designed that would help up the burn time along with extending the delays.
There are TONS of WAY more productive project available in the micro model range then trying to make a reloadable Micro.

green dragon

3rd March 2010, 02:36 PM

13mm single use composite motors (again, not reloadables) would be less of a technical challenge, but even then, where would the market be? Would anyone really want to spend something like $5-$6 for a 13mm C? And, returning to the first topic above, who would pay $4 for a 6mm A? Is there such a demand for the Aerotech RMS 18/20 motor that people are clamoring for something smaller? You can purchase 13mm hardware from GMA or else make your own, but how many people are actually doing that? Especially since you need to be a member of Tripoli with at least Level 2 certification in order to have sanction to cook up your own propellants and cast your own motors.

MarkII

Well, I htink there is a small market for 13mm composites, moeso then 6mm market - I fondly recall the Apogee B7 composite motors, and although pricey at 5-7.00 , they were nice for the ' had to try a few' factor :)

personally, I would LOVE to see the AT RMS18 reloads in B-C sizes return, especially the C12 and C4 reloads. but again, most persons flying would rather have single use BP at lower cost.

I do have the Green MOnkey 13 and 18mm hardware, yet to burn any - maybe this summer at a PYRO launch, come on out to one :)

~ AL

Micromeister

3rd March 2010, 02:58 PM

We also fondly remember the Apogee 10.5mm BP, B2-7 and -9 motors as well.

the Problems with AP...is COST pre flight. At least when it comes to Model rocketry!

ScrapDaddy

3rd March 2010, 08:12 PM

Acctually it wouldnt make sence to make a C4 or A C12 as Estes makes quite a few close alternatives, the c6 and the c11 (although that is a 24mm); although it would add a verity to the limited choises we have in the 18mm reloads. But Isnt really cool to think about the miniscule chance that there could be a 6mm reload?

MarkII

4th March 2010, 01:57 AM

We could have more reload options for the RMS 18/20 motor if we would actually buy them. Aerotech did try to offer a broader range; at one time, they produced reloads ranging from B to E for it. But as Bob said, very low sales killed all except the Ds. "Very low sales" means that customers just didn't want those other reloads. The 18mm D motors, in contrast, fill an actual need, which is why they sell in enough quantities to warrant their continued production. Ask yourself: would you actually buy many 18mm composite C6s? And how many people do you suppose would build rockets to fly on 18mm composite E27s? I mean, there is a reason why you don't see many 14" long by 1" diameter MPRs. Think about it.

I'm sure that there have been people who have experimented with creating 6mm composite motors, but I doubt that their creations were capable of doing anything that black powder Micromaxx motors don't already do or couldn't be manufactured to do. When you get down to that scale, I don't think that composite propellant possesses any meaningful advantage over black powder. Current Micromaxx motors already put out a pretty impressive amount of thrust and have decent power for their size and mass. You have to pick one up and hold it in your hand to appreciate how tiny those motors really are. That they can be manufactured at all, with the same set of features and the same (or better) reliability as conventionally-sized black powder motors is truly a miracle itself, one that isn't always fully appreciated. APCP has a much higher specific impulse compared to black powder, but you have to make motors that are a bit bigger than micro-sized before it actually begins to matter.

MarkII

ScrapDaddy

5th March 2010, 03:58 AM

Well I can see where you are going with the B and C reloads but what was the problem with the E27 reload? It really doesn't have a compeditor in the 18mm range.

Back to the 6mm reloads; what's wrong with making a 10 Inch long reload?; it would give a nice long thrust (with a debatible amount of force) and why couldn't use an end burner to solve the ignition problems?

MarkII

5th March 2010, 04:35 AM

Well I can see where you are going with the B and C reloads but what was the problem with the E27 reload? It really doesn't have a compeditor in the 18mm range. Duplication would be my guess. Anything that was big enough to fly on an E motor was big enough to launch on a 24mm E. Therefore an E reload for the RMS 18/20 would fill exactly the same niche as the E reloads for the RMS 24/40. If the rocket required an 18mm mount because it was too small for 24mm, then it was also too small for an E motor. I'm sure that there were exceptions, but probably far too few to justify the expense of producing 18mm E reloads.

Are you unable to understand the fact that a company will do nothing but lose money on a product like that if it only sells a half dozen of them over the course of a year? It costs a company significant money to produce such an item; the company has to be able to sell enough of that product to make that money back, along with a little bit of profit. If it can't sell enough of them, it will stop producing them. People didn't buy the 18mm E reload; that's why Aerotech stopped making it.

Back to the 6mm reloads; what's wrong with making a 10 Inch long reload?; it would give a nice long thrust (with a debatible amount of force) and why couldn't use an end burner to solve the ignition problems?I can guess why no motor manufacturers have made them; any EXers who might be reading this could also give you their reasons for not having done so, too.

MarkII

ScrapDaddy

5th March 2010, 11:46 PM

Sooo 6mm reloads are not coming soon :eyepop:

MarkII

6th March 2010, 12:07 AM

Sooo 6mm reloads are not coming soon :eyepop:I think that it is far more likely that we will continue to see further development in the larger diameters, especially 24mm and 29mm. This is where the advantages of APCP really begin to shine, and where one can really start to see savings from using reloadable motors.

MarkII

ScrapDaddy

6th March 2010, 12:16 AM

I guess areotech cant do Everything:dark:

MarkII

6th March 2010, 01:03 AM

I guess areotech cant do Everything:dark:Creating a 6mm diameter reloadable motor isn't an unmet need; it's just a stupid idea. :bangpan:

MarkII

ScrapDaddy

6th March 2010, 01:20 AM

toche:blush:

dwinings

6th March 2010, 04:24 PM

I still have one or two 10mm composites (A's) that were made for the US Team at one time, but they're not commercially practical, neither would 6mm ones.

Dan

The EGE

6th March 2010, 05:43 PM

I still have one or two 10mm composites (A's) that were made for the US Team at one time, but they're not commercially practical, neither would 6mm ones.

Dan

Many FAI folks in Europe use the Czech Delta motors; they're 10.2mm x 34mm A2-7 motors: http://www.cyber-heritage.co.uk/redglare/lili.jpg

Lots of information on all sorts of wild and weird European motors on that page:

http://www.cyber-heritage.co.uk/redglare/

ScrapDaddy

7th March 2010, 05:29 PM

wait till you use some motors that were made in china.......:dark:

MarkII

7th March 2010, 06:01 PM

wait till you use some motors that were made in china.......:dark:Which ones? :confused: And what should we expect to see when we use them? :confused2:

MarkII

Shade

7th March 2010, 06:55 PM

3) Hardware would be really really expensive to machine in such a tiny size at low production volumes. And it'd be so thin that it'd be easy to break.

First I will not or cannot discuss any of your other points, however,
machining reusable casings would not be a barrier. The majority of
the cost of the current reloadable casing is more attributed to the
anodizing and not the machining. 6mm casings are anything but tiny
by machining standards. There are common CNC machine tools
(Swiss style machines) that 6mm diameters would be considered large.

The EGE

7th March 2010, 10:53 PM

First I will not or cannot discuss any of your other points, however,
machining reusable casings would not be a barrier. The majority of
the cost of the current reloadable casing is more attributed to the
anodizing and not the machining. 6mm casings are anything but tiny
by machining standards. There are common CNC machine tools
(Swiss style machines) that 6mm diameters would be considered large.

Huh... Things I never knew...

jj94

8th March 2010, 02:35 AM

You could do reloadable 6mm motors just for fun, but I highly doubt seeing it in retail markets. I've seen a website that had a page dedicated to 6mm reloadables. I forgot the website though, because it's been such a long time since I looked at it. I remember the URL having "scott" in it (I think...). I know the website had some stuff with high altitude balloons too.

kullas

8th March 2010, 03:21 AM

Was it Scott Fintel at http://www.thefintels.com/aer/rocketindex.htm

dwinings

12th March 2010, 07:14 PM

Many FAI folks in Europe use the Czech Delta motors; they're 10.2mm x 34mm A2-7 motors: http://www.cyber-heritage.co.uk/redglare/lili.jpg

Lots of information on all sorts of wild and weird European motors on that page:

http://www.cyber-heritage.co.uk/redglare/

I have some of those Czech motors too, but I'm talking about 10mm composites with Aerotech grains and of American manufacture, made the same way as Aerotech composites of the time, with graphite nozzles. One of them included a 13mm composite C I flew in a 13mm Sandhawk for Scale Altitude.

Dan

ScrapDaddy

12th March 2010, 09:47 PM

well thats pretty intesting

jj94

20th March 2010, 07:27 PM

Was it Scott Fintel at http://www.thefintels.com/aer/rocketindex.htm

YES that was the website. I guess they removed the 6mm reloadable page.

ScrapDaddy

21st March 2010, 04:08 AM

Darn I sure wouldve love to see some pics on how they worked

ScrapDaddy

27th March 2010, 12:16 AM

Couldn't you solve the ignition problem by using a D slot configuration? that way you can use a mini copperhead?

The EGE

27th March 2010, 02:12 AM

First reaction.... NUUUUUUUUUOOOOOOOO!!!!!! Not more Copperheads!!!!

Second reaction: still not gonna work. You're talking about a really tiny Copperhead - almost thread-thin - and it's gonna be well-nigh impossible to get that into a teeny tiny nozzle without snapping it.

Let's face it - there is almost no way to get a 2-wire igniter or Copperhead, of any sort, with any pyrogen at all, into a 1.2 mm hole. It's not gonna be easy, and no way anyone is gonna make a commercial system out of it.

If you want one, then you are going to have to wait at least 6 years, until when you are 18, L2 certified, and possibly possessing a LEUP. And please, get some experience making larger motors first, because starting with a non-commercial case and tiny motor parts does not sound like a good idea...

ScrapDaddy

27th March 2010, 02:27 AM

I still deem this on my rocketry bucket list :D

Chrisn

27th March 2010, 04:40 AM

Why dont you put 6 foot (diameter) reload composites on your bucket list, sounds more exciting to me.

ScrapDaddy

27th March 2010, 04:44 AM

How much do you think it would take to pay aerotech to start making 6mm propelent kits and produce them under my name? $10k? I bet I could get rouse tech to make the hardware, problem solved

MarkII

27th March 2010, 04:52 AM

How much do you think it would take to pay areotech to start making 6mm propelent kits and produce them under my name? $10k? I bet I could get rouse tech to make the hardware, problem solvedNever heard of that company - "areotech." :confused2: And what is "propelent?" :confused: Has anyone besides Scrappy ever heard of them?

Mark K.

JAL3

27th March 2010, 04:54 AM

How much do you think it would take to pay areotech to start making 6mm propelent kits and produce them under my name? $10k? I bet I could get rouse tech to make the hardware, problem solved

I bet that wouldn't even pay the liability insurance!

jsdemar

27th March 2010, 02:45 PM

For some reason, I missed this thread earlier in the month.

About 8 years ago, I made some 11mm composite motors with carbon-fiber casings. The casing material was made from larger-diameter arrow shafts. The nozzles were molded from furnace cement (some with a ceramic washer throat), and I also made some tiny graphite nozzles.

http://thrustgear.com/micro/

I've made up to 6" diameter P motors, but these tiny composites were by far the most challenging to make of any size!

To get a reasonable long burn, it has to be an end-burner. To get reasonable thrust from an endburner, it has to be a very fast propellant. This means handling additives and particle sizes that are riskier than normal. For example, the same propellant as a core-burner in a 38mm casing burned in 0.4 secs with 100 pounds of thrust!

Next problem is getting an igniter in the nozzle and getting it to light. I'd pre-coat the end of the grain with pyrogen and insert a very fine gauge nichrome igniter. Nothing else would fit through the nozzle. I'd get about 1 out of three to ignite.

The biggest problem with a long endburner is heat soaking into the casing and burning through. To get enough volume of propellant and keep the diameter small, the liner and casing can't be very thick. An aluminum casing (or ceramic) would be better, but too expensive and time-consuming to produce.

-John

kullas

28th March 2010, 03:18 PM

instid of carbon fiber why not use aluminum arrow shafts.

I took some rcandy and stuffed into a used mmx case after i cleaned it out even reused the nozzle. i took a drill bit and drilled out the core about 3/4 the way through so i would have a delay put some power on top of the rcandy for ejection charge. took a standard igniter for mmx and lit it. It worked and about as well as the mmx motor even had almost a 2 sec delay. but i want do it again its just to much work for what ya get

Micromeister

30th March 2010, 01:56 PM

kullas

2nd April 2010, 02:50 AM

i was using KNO3 and sugar with a little RIO. by the time ya rolled it into that small of a ball to stuff it in there it was hard :( just to much work for such a small motor

Blakkzakk

25th October 2010, 06:01 PM

Green Monkey Aerospaces name can be displayed on TRF, not sure why people have issues with that.

6mm reloads are not that hard. reloads would be a pain to assemble but not that bad.

Ben

I checked out the Green Monkey website. Where do you get reloads?

JAL3

25th October 2010, 06:35 PM

I checked out the Green Monkey website. Where do you get reloads?
Green Monkey is strictly hardware.

You have to brew your own.

stickershock23

25th October 2010, 06:52 PM

This is all great, as long as you don't live in Cali.. if you do you would need a cal pyro 3 and a Level 1 cert to fly a 1/2 "A" motor :roll:

mwtoelle

25th October 2010, 11:27 PM

The E27 reloads were only about 22 N-s, and were available with a four second delay. The propellant grain and delay element filled the available space in the casing. You could only use this reload in rockets that weighed between 10 - 14 ounces. The E27 was discontinued probably for the same reason that the E25 single use motors were discontinued. They were barely an E and didn't offer enough value over the D21, D13, and D24 motors that are currently manufactured.

Well I can see where you are going with the B and C reloads but what was the problem with the E27 reload? It really doesn't have a compeditor in the 18mm range.

DaveHein

25th October 2010, 11:56 PM

A 6 mm reload? We're talking about 6 millimeters, correct? Isn't that less than a quarter inch? I don't get it! (http://www.youtube.com/watch?v=U1_ZEL0ehkE) :confused2:

MarkII

26th October 2010, 12:37 AM

A 6 mm reload? We're talking about 6 millimeters, correct? Isn't that less than a quarter inch? I don't get it! (http://www.youtube.com/watch?v=U1_ZEL0ehkE) :confused2:Neither do I, and I think that SD realizes now how unrealistic it would be. When I showed him a MicroMaxx motor this summer, he was shocked at how tiny it was.

Gnomad

26th October 2010, 12:41 AM

A 6 mm reload? We're talking about 6 millimeters, correct? Isn't that less than a quarter inch? I don't get it! (http://www.youtube.com/watch?v=U1_ZEL0ehkE) :confused2:

It is the challenge to make it work! As others have mentioned, manufacturing gets progressively more difficult below a certain size. And if you are into research/experimental motors, the ability to launch in your back yard is a big plus.

eugenefl

26th October 2010, 01:09 AM

You could always bring this guy (http://www.willard-wigan.com/video.aspx) on as a design consultant. :cyclops:

kramer714

26th October 2010, 07:26 PM

making life too hard....

Thinking outside the box, the goal is cheep not reuseable,

1) why not make a nozzle AND case by swaging a piece of thin steel tube, when you swage the nozzle the material gets thicker, not a lot of erosion on something this small, is it optimized, nope is it good enough, maybe, is it cheep and strong, heck yes. Can do by hand, swiss screw machine would pop them out.

2) casting grains, cast a sheet and stamp them out, stack them like a roll of 'Smarties' (end burner) or Lifesavers (core Burner). put the igniter in from the top side and feed the wires out before pressing in the forward closure, could even have a black powder 'Smartie' on top of the stack.

3) forward closure, press fit /swage. Simple tool again cheep and good enough would not be hard to seal.

4) Ignition,
A) put the igniter in from above (see item 1 and 2)
B) treat one of the 'smarties' with conductive pyrogen, short the case for one wire of the ignition system and have a needle touch the pyrogen on the 'Smartie' on the inside. You will need to have some insulation where it passes through the nozzle but that can be as simple as magnet wire insulation (varnish).

make patent royalty payments to...

MarkII

26th October 2010, 07:59 PM

making life too hard....

Thinking outside the box, the goal is cheep not reuseable,...

make patent royalty payments to...Once again, where is the market for this?

kramer714

26th October 2010, 08:06 PM

Once again, where is the market for this

Not really a market at all, I thought that was a given at this point,

But, if you wanted to do it I just threw out one way to go...

the patent payment comment was a joke...

My latest patent cost around $10k by the time the dust settles. I don't think that the ROI is very promising for 6mm reloads.

Gnomad

26th October 2010, 08:16 PM

Thinking outside the box, the goal is cheep not reuseable,

That's not thinking outside the box, that's exactly how the Estes motors have been made for nearly 60 years now, as well as the chinese rockets 1000 years before that.

make patent royalty payments to...

If ever there was a case for "prior art"... ;-)

brianc

27th October 2010, 01:59 AM

It can (has) be done- Jimmy Yawn posted this to the SugPro list
in December 2008 -

...interesting gentleman in
Switzerland, Mr. Torbjörn Winther, who is active in sugar rocketry, and
has made some small motors.

Very small motors.

I've placed photos of a few of his works on the web at:
http://www.jamesyawn.net/winther/

Blakkzakk

27th October 2010, 09:47 PM

Green Monkey is strictly hardware.

You have to brew your own.

OK. Sounds like I'd have to do just that. I've been meaning to get into home-brewing propellants, anyway.

MarkII

28th October 2010, 01:52 AM

Not really a market at all, I thought that was a given at this point,

But, if you wanted to do it I just threw out one way to go...

the patent payment comment was a joke...

My latest patent cost around $10k by the time the dust settles. I don't think that the ROI is very promising for 6mm reloads.OK then. Way back when the thread started it was to ask why Company A or Company C didn't make 6mm diameter reloadable motors (or Company G or Company L). but it was so long ago I forgot how that particular question was resolved. But sure, I get what you are saying. Someone might want to build such a motor just for the coolness factor. I have been tempted to buy an RMS 18/20 motor just to have a miniature reloadable motor. It's pretty small, after all. A 6mm reloadable would be one third the size of it! As I mentioned earlier, when I met the OP at a club launch this summer and showed him an actual MicroMaxx motor, he was astonished. He told me that he had not realized how small 6 millimeters actually was. Now Quest can just barely fit 0.218 Newton-seconds of impulse (plus a vanishingly brief delay grain and a tiny but surprisingly capable ejection charge) into the existing MMX motor length (6mm x 25mm, roughly 1/4" by 1"). It's packed like an 18mm C6-7 - completely full end to end with not a hair's breadth of space left over. Granted, this is with black powder. And the opening in the clay nozzle is barely visible without magnification. In order to improve on the 1/8A impulse (increasing it to, say, 1/4A) would require a much longer case. So setting aside for now the issues of whether you can reliably cast propellant grains that small that can be handled and loaded and all of the issues with using truly tiny parts, has anyone ever successfully burned 2" or 3" long composite fuel grains that were loaded inside a 5.25mm to 5.5mm ID metal tube that was sealed at one end? Is a burn even stable and sustainable over that length within such a narrow space? I don't know what the answer is; does anyone?