Nozzle vs Nozzleless

[dagabu]

@SekondAmendment,

 

Honestly, I have an ego too and you stepped pretty heavily on it in a patronizingly way by using what I wrote and applied it to hi-tech items and ignoring the spirit of my reply, "it is mostly irrelevant for pyrotechnical use". The remainder stands correct in that context. Also, one cannot call another childish without themselves looking childish as it is childish to do so (see the problem here?) and therefore I have become childish in responding to your rebuttal.

 

A good friend of mine once told me to shut up after getting into an argument with another friend. He said something profound, "Any man that has to resort to attacking another's character has already lost the argument." You need to take a hard look at that as well my friend.

 

I think that a good hard look at the data provided will show that the simple use of my examples will stand in pyrotechnic rockets just fine with no inaccuracies. If my reply is used to defend the missile systems and other Hi-Tech systems then it is very wrong and thus should be called to question just as you did.

 

Now, if we can move on to rudimentary clay nozzles and paper tubes used to loft a paper shell up around 600', I would appreciate it.

Edited May 15, 2013 by dagabu

[Bobosan]

nater, are your result charts in OP taken with Peret's thrust stand and is that going to be the standard measurement tool? Edited May 15, 2013 by Bobosan

[dagabu]

There aren't a lot of other test stands out there but they should all record the same information. Our test stand has software that can interpret the data of the other test stands too making their curves viewable in the same way data the ACME rigs display the data.

 

Let myself or Peret know if a data dump needs to be translated.

[nater]

Yes those curves are from the Acme Test Stand and software. Like Dag said, any stand should give the same information.

[Bobosan]

While I can not participate since no device for testing thrust, I submit the suggestion that 3 individuals with the same ACME stand run these comparisons. I don't know what kind of pre-use calibration is involved with the ACME stands, but they should all be calibrated identical pre-testing. I'm thinking using identical measurement tools would eliminate the need for data interpolation and possible errors. You've already fixed the rocket tooling and motor size.

 

The tubes to be used for testing - will they be from same vendor?

 

Other things that should be considered as identical fixed items;

 

Nozzle material used.

Press pressure.

Method of tube support during pressing.

 

There are more that could be added to the list but it becomes a bit anal to go deeper for the question you want to answer.

 

I'm very interested in the results you guys find but would like to see as many basic controllable constants applied across the board while knowing there will be uncontrolled variables such as fuel.

Edited May 15, 2013 by Bobosan

[Mia]

Wow guys this is turning in to some sort of rocket science? Well I thought for what is worth let me say this I buy in a lot of pigeon motors from China now there 19mm id and 120mm long if you’re lucky, the tube looks like it came off a roll of some form of water pipe it’s clear to a point some of the motors still have a slight bend to them! It’s just a tube filled with BP highly compressed on top of a clay plug with no divergence or convergence the core depth is around 78% and no taper on the core my question is how come I can lift 150gram shells with that set up with ease to around 180 feet? Don’t add up dose it when you think about it, I would say the Chinese must be on some hybrid fuel or running on basics! Edited May 15, 2013 by Mia

[dagabu]

While I can not participate since no device for testing thrust, I submit the suggestion that 3 individuals with the same ACME stand run these comparisons. I don't know what kind of pre-use calibration is involved with the ACME stands, but they should all be calibrated identical pre-testing. I'm thinking using identical measurement tools would eliminate the need for data interpolation and possible errors. You've already fixed the rocket tooling and motor size.

 

The tubes to be used for testing - will they be from same vendor?

 

Other things that should be considered as identical fixed items;

 

Nozzle material used.

Press pressure.

Method of tube support during pressing.

 

There are more that could be added to the list but it becomes a bit anal to go deeper for the question you want to answer.

 

I'm very interested in the results you guys find but would like to see as many basic controllable constants applied across the board while knowing there will be uncontrolled variables such as fuel.

 

As far as the ACME test stand goes, why don't you get together with another Indiana pyro that has a test stand and do a bunch of tests? I am willing to rent out my personal (ACME Rocket Test Rig #2) test stand if a deposit accompanies it.

 

Yes, the load-cell and test stand are calibrated and tested against known weights before shipping. A test rig calibration can be performed by the owner at anytime (PC must be attached). The load cell is also calibrated before it leaves the factory, it cannot be changed.

 

The tube and nozzle, tube support who manufactures what are not issues for me as long as we can agree on how much erosion is allowed in throat portion of the nozzle. The clay again is not an issue for as long as it can withstand the erosion enough to stay within the parameters we all decide.

 

As far as loading pressure, I will be pressing my motors to the same LPI as Nate, I trust him with my life... literally.

[dagabu]

Wow guys this is turning in to some sort of rocket science? Well I thought for what is worth let me say this I buy in a lot of pigeon motors from China now there 19mm id and 120mm long if you’re lucky, the tube looks like it came off a roll of some form of water pipe it’s clear to a point some of the motors still have a slight bend to them! It’s just a tube filled with BP highly compressed on top of a clay plug with no divergence or convergence the core depth is around 78% and no taper on the core my question is how come I can lift 150gram shells with that set up with ease to around 180 feet? Don’t add up dose it when you think about it, I would say the Chinese must be on some hybrid fuel or running on basics!

 

I'll take a couple cases of those please!!! I have had a few over the years and I agree, they lift very well but I have NO idea what the fuel is.

[Bobosan]

As far as the ACME test stand goes, why don't you get together with another Indiana pyro that has a test stand and do a bunch of tests? I am willing to rent out my personal (ACME Rocket Test Rig #2) test stand if a deposit accompanies it.

 

Yes, the load-cell and test stand are calibrated and tested against known weights before shipping. A test rig calibration can be performed by the owner at anytime (PC must be attached). The load cell is also calibrated before it leaves the factory, it cannot be changed.

 

The tube and nozzle, tube support who manufactures what are not issues for me as long as we can agree on how much erosion is allowed in throat portion of the nozzle. The clay again is not an issue for as long as it can withstand the erosion enough to stay within the parameters we all decide.

 

As far as loading pressure, I will be pressing my motors to the same LPI as Nate, I trust him with my life... literally.

 

If you rent out your ACME, what are you going use Dag? Seriously, I'd like to take a close look at one sometime and wish I could afford it or even the deposit on one! Only contact I casually know in Indiana (through APC) with an ACME is nater unless one of the other BPG members might have one.

 

Besides that, the largest motor I have rammed is 4oz. Don't have a press yet.

 

Was thinking in terms of tube support method rather than who made it...or where the tubes were made, etc. Nozzle material? One persons mix may be better than another with erosion. Shouldn't all testers use the same nozzle mix to eliminate a variable that might result in CATO with Tester A's fuel vs. Tester B's fuel with a successful curve? Same with the tubes and method of support.

 

I realize this may go beyond what you are after (nozzled vs. nozzless thrust) but lends itself to further analysis and comparison of the fuel variable. Call it a subcategory if you will.

Edited May 16, 2013 by Bobosan

[psyco_1322]

Using the same nozzle mix might be a good idea. It would be quite easy considering you don't use much and a decent sized batch would be easy and cheap to mix up.

 

I don't see the tube or tube support changing the thrust variable at all. NEPTs are pretty standard anyways, hardly no one uses a weaker tube unless making masses of lower output rockets.

[nater]

We all have slightly different materials for making nozzles. I use typically a mixture of Hawthorn Bond clay and powdered graphite. I think if we agree on a nozzle that is 1 ID tall, our results will be close enough to be acceptable.

[Bobosan]

I don't see the tube or tube support changing the thrust variable at all. NEPTs are pretty standard anyways, hardly no one uses a weaker tube unless making masses of lower output rockets.

 

What method of tube support is used most often with 3/4"? I've seen pics of split PVC with hose clamps, split steel pipe with hose clamps and solid blocks of split steel or aluminum with built in screw clamps, etc. PVC does not seem to be a good choice under the pressure hydraulics would exert.

 

The tube support and tube are just a couple of variable data points that could be fixed and added into the database that has been proposed. I agree that they are not a huge factor in the nozzle vs. nozzleless thrust tests.

[nater]

I use NEPT from Hobby Horse and a split piece of PVC with hose clamps for support. Like I said earlier, I press all my motors to 7500 psi on the comp. For a 3/4" motor, that means I am pressing to 3300 lbs. I haven't had any problems with that kind of pressure. Just judging from different build events, PVC supports seem to be the most popular choice as well.

[Bobosan]

Interesting. Thanks nater.

[Mumbles]

If a collection of data ever materializes, it should be apparent pretty quickly what effect the nozzle has if there is no universally agreed upon standard. I suspect the biggest difference, if any, would be in the tail end of the thrust curve where erosion would become a factor.

[psyco_1322]

I sometimes use a PVC support with hose clamps, and it's fine with the 4000+lbs I press my whistle rockets at. Most people are using PVC supports or Aluminum clam/split supports that are commonly available from the suppliers.

 

I'm just saying that regardless of the support, regardless of the tube, the thrust should not be altered by those variables.

Edited May 16, 2013 by psyco_1322

[ddewees]

Sorry to bring this old thread back, but was this ever done? Curious to see the results.

[Beraq]

If this is considered kicking up a dead thread unnecessarily, my apologies.

 

i've tried a few different rockets (core burner, end burner, nozzleless), and found the nozzleless rocket to be the most reliable.

My core- and end burner rockets all blew up at ignition, probably because my meal powder is very fast.

Now I use nozzleless rockets with a 15 mm. ID and a 5 cm core.

These rockets are very reliable, and are able to lift a 200 gram payload to a respectable height.

Here's a video:

 

 

The rockets contain 18 grams of 75-15-10 meal powder made with birch wood, milled for 3 hours.

 

Excuse any spelling errors, i'm a Dutchman.

 

[ddewees]

Looks good

 

I've pretty much gone nozzleless too, other than a few that will only fly with a nozzle.

[leedrill]

id like to now comment on this old thread and try to add my 2 cents

ive now moved to nozzle-less motors for bp coreburners {i only run 3lb motors }. When i started making motors i noticed how many of the pros used no nozzle for their work horse motors and to be honest my naivety got the better of me. I was thinking ha, idiots as if a motor with out a nozzle would have more power but with factors in what we do such as tube strength and fuel now have shed a new way of thinking for me after trying no nozzle and experimenting with redline on a 3lb coreburner with a nozzle

i will honestly in my opinion say id be able to lift more weight with one single nozzle-less 3lb motor than what i would be able to on one with a nozzle

now to say to people who are about to jump at me for saying that

the fuel i can run in a nozzle-less motor can be crazy hot like i could probably run toned down whistle fuel for my 19cm spindle with out a cato

and with a nozzle i can run 1/3 of that spindle with 75/15/10 and the rest at 65/25/10 with out a cato and any more hot bp will be a cato

now this raises the point of of course a nozzle-less motor has less power with the same fuel as is optimal for a nozzled motor and a nozzled motor is more efficent having a slower fuel it will have a longer thrust phase

but there is no way to get more power out of them once optimised with bp

as for the hottest bp i can make will not cato a motor with no nozzle and my spindle is not little i can add a lot more power to the fuel and there fore get a lot more lifting capability but the maximum lifting capability might be higher in weight but the height achieved will not be a significant difference

 

but in my last statement id like to say hotter fuel and less work means i dont need to make any 60/30/10 or anything like that for my coreburners so i can use the same meal for everything and not have to weigh out clay for a nozzle each time its a win win for me

[Col]

To get more lifting capacity from an optimised motor, just stack 2,3 or 4 on the same stick

[Juiceh]

My .... end burner rockets all blew up at ignition, probably because my meal powder is very fast.

.

 

Doubtful. If your BP endburner blew up it was far more likely from a crack in the fuel grain, insufficient consolidation of the fuel grain or nozzle, fractured tubes, or some other fault. In a properly constructed end burner motor you can use some whistle fuels or whistle-BP blends behind a nozzle and they are much hotter mixes than the hottest BP you will ever be able to make.

What were your loading pressures? I use 10k psi on the fuel grain.

[dagabu]

Sorry to bring this old thread back, but was this ever done? Curious to see the results.

 

DD, two days after that rant, I was admitted to Regions Hospital in St Paul for 6 weeks, almost all of that time I spent in a Coma. I may come back to this thread some day but my ego is substantially smaller now and I think I need to spend some time combing through the rubbish to make a valuable reply. I dont think I can do that today, not yet.

 

The bottom line for me is that I have all but abandoned nozzled rockets, the little bit of extra fuel needed to make a nozzleless rocket motor v.s. the greater likelihood of a CATO for a nozzled rocket motor is just not worth the little extra thrust phase length.

 

I burned two motors yesterday and even with ridiculously hot fuel (one was a hybrid), they burned well with no CATO in cheap pulpy tubes.

[dangerousamateur]

 

I burned two motors yesterday and even with ridiculously hot fuel (one was a hybrid), they burned well with no CATO in cheap pulpy tubes.

 

Did you play some expert tricks with you tubes, like waxing or using of strong supports?

 

 

 

I agree, nozzleless is superior. Every time I try nozzled rockets, I get catos. Not always, most work fine, but not more than 80%.

With nozzleless and 1lb standard bp tool I get almost 100%. With more power.

[dagabu]

Neither one, I used Davids Brass Shim Stock support and dry tubes. I don't overdo the pressure either, about 4000 LPI on riced BP.