Why not hybrids?

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Hey, that is a good idea. There was one thread about a year back on a "research" grain build for standard hardware. Since this does not involve any flammable chems, I wonder if we could cross post and/or make it sticky in this group?

You mean like making a hybrid for an otherwise normal case like a Loki 54/4400? Or making a research grain for Contrail hardware?
 
You mean like making a hybrid for an otherwise normal case like a Loki 54/4400? Or making a research grain for Contrail hardware?

No, it is the fuel grain for a hybrid system like Contrail, Skyripper, etc. Nicely done thread that included ISP calculations, grain sizing, etc. I just can't remember who authored it and thus have had a hard time finding it.
 
You don't really need permission... Do you? Look at KBA animal compatible, or CTI in Aerotech hardware.
However they do require certification.......to be sold to the general public.

Bob
 
US sizes are 20#, 35# and then you can get a K cylinder from AirGas, Praxair etc. K's are not THAT bad provided of course you have a wheeled dolly or a pickup truck to haul it to the pad, no worse than a big L3 rocket. You have to make a mount so you put it upside down because there is no DIP tube. You can rent the tank by the month.

With a dip tube tank you do not get all the capacity of the tank because the tube may not get all the way to the bottom. On my Catalina 20# alumimum I can only get about 17 of the 20#. On my next fill I will ask my gas shop if he can fit a longer tube.

I took apart my 20 lb. tank and extended the dip tube so that it was less than half an inch off the bottom. I still can't get that last 3 lbs. out of it. I suspect that when it gets that low the gas just bubbles through the liquid.
A full 20 pound cylinder of N2O contains both liquid and gaseous N2O with a DOT mandated ullage (headspace) volume of ~30% IIRC. I believe that getting ~85% of the N2O out as a liquid is about what you can expect, as some fraction of the nitrous must turn into gas to pressurize the non-liquid volume of the cylinder.

Bob
 
You don't really need permission... Do you? Look at KBA animal compatible, or CTI in Aerotech hardware.


The KBA reloads are with permission of Frank Kosdon who held the patent to those motors. Not only that but they are certified for commercial use. I think that certification is the real cost involved. If Todd were interested he could probably contract out the fuel grain manufacture. The key is "if Todd were interested".

A while ago when Alpha quit making motors Contrail inquired about making the motors but no deal was made.
 
The KBA reloads are with permission of Frank Kosdon who held the patent to those motors. Not only that but they are certified for commercial use. I think that certification is the real cost involved. If Todd were interested he could probably contract out the fuel grain manufacture. The key is "if Todd were interested".

A while ago when Alpha quit making motors Contrail inquired about making the motors but no deal was made.

The KBA Animal compatible reloads are for AMW bulkheads and nozzles, not the Kosdon ones. No permission from AMW was arranged.
 
A full 20 pound cylinder of N2O contains both liquid and gaseous N2O with a DOT mandated ullage (headspace) volume of ~30% IIRC. I believe that getting ~85% of the N2O out as a liquid is about what you can expect, as some fraction of the nitrous must turn into gas to pressurize the non-liquid volume of the cylinder.

Bob

But the liquid density is much higher than the vapor density. So when you have 20# of nitrous in the bottle most of that 20# is liquid. If you do not use a dip tube and instead invert the bottle to fill wont you get almost the entire 20# of the N2O in liquid phase before the tank "blows down" the rest with vapor?
 
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The KBA Animal compatible reloads are for AMW bulkheads and nozzles, not the Kosdon ones. No permission from AMW was arranged.

You are probably correct. CTI has also certified some of their reloads for use in Aerotech style hardware which I am sure was without permission from Aerotech. So certification is the real hurdle.
 
Very nice... Thanks...

What is your ignitor and ignition sequence??

It looks like you have an AP preheater and a pneumatically driven ball valve releasing the Nitrous. Do you have a valve in-mind for flight hardware??

--MCS

.

Yes that round of tests we used some AP/ignitor +O2 for the ignition, (Not ideal)
We have been using Spark+O2, but the spark generator was being intermittent on the day, so we bypassed it.

Not sure with the flight motor at this stage, it will depend on what size we go with.
 
Hybrid Starts of the weekend... first the KRAMER X4, flying a 48" Contrail K-Something (no TMT reference available!) with Sparky II and XFast nozzle to leave the 18kg beast from the ground..easily obviously. I rate the sparky more powerfull than the Black Gold, rated K555 (1700Ns total, 1200 peak)

IMG_3019_k.jpg

Start at 0:42", here the full flight from filling to landing in front of the ESA Radiotelescope....

[video=youtube_share;8u9yH55uYn4]https://youtu.be/8u9yH55uYn4?list=UUetxVh1q3FgTZgrVGTMykkw[/video]
 
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...And the next one....this morning, same place in bella Italia....a beautifull beast: my Wildman Eagle Claw 4" with a CONTRAIL K555 Black Gold Reload (Medium speed, 1/4 injector)...

eagle claw bologna start 2014.png

Do not forget the HD settings in youtube...here the full flight from filling to landing, start at 0:26"

[video=youtube_share;501sUHZqX1M]https://youtu.be/501sUHZqX1M[/video]
 
is there a lower resolution video you can upload? A 4K 2160p only option is consumes too much bandwidth here for me.
 
John I am not sure why you can't get other resolutions on your side. Here I get multiple choices from low to very high...Maybe we shall wait few minutes? Sometimes Youtube isn't that quick to release videos.
Denis
 
You're right. Lower resolution choices available now.
 
Very nice flights Denis, thanks for sharing... too bad about your igniter trouble on the cluster project, hopefully everything will work at your club launch in 4-weeks..
 
But the liquid density is much higher than the vapor density. So when you have 20# of nitrous in the bottle most of that 20# is liquid. If you do not use a dip tube and instead invert the bottle to fill wont you get almost the entire 20# of the N2O in liquid phase before the tank "blows down" the rest with vapor?
A couple of your assumptions are incorrect.


1. The liquid density decreases with temperature up to the critical temperature and then drops to 0 since liquid nitrous oxide not longer is possible above the critical temperature.

2. The nitrous oxide vapor pressure and therefore density increases with temperature up to the critical temperature.

3. At the critical temperature the liquid and gas densities are equal.

4. At 25C (room temperature) the density ratio is 3.75.

4. DOT 3AL tank specifications for rated tank capacity requires that the rated weight capacity include a 30% gas (ullage or headspace) volume. If you ignore the law, you can put significantly more nitrous by weight into the tank at the risk of a sudden tank rupture should the liquid flash over to gas.

See attachment for densities.

Bob

View attachment nitrous chinese document.pdf
 
Ok, here is how all the welding shops and speed shops that I have been dealing with for 10 years fill by bottle.

They put the bottle on a scale. Then they pump N2O into the bottle until the total weight = tare weight + 20#.

So I have 20# of liquid and vapor in the bottle. Taking the density chart, at 20C gas is about 18% by mass and liquid is 82% by mass. So I can expect to get 0.82*20 = ~16# of liquid N2O out of the bottle. In the motor tank I can then expect this to separate into vapor and liquid by the same ratio in the bottle.

Correct?
 
this fits exactly to my painfull experience of the past years. Take content in kg / 1.2 x 0,8 and you have really usable liter content for our hobby, as a simple rule of thumb.
When the sum of the volume of the motors fired with said same bottle achives the usable volume calculated above, change the bottle, do not even think more, especially for motors at J and more impulse. No way you can get the tank full next time. this means too you shall track what happens with the bottle, what motors you filled and what you plan next meeting if the bottle is not empty. just avoiding surprises.

one thing i would like to know: do we know a safe method to fill from a large tank into a small tank, using common plumbing and hardware? and how? typically I prefer to carry small bottles on the field but only pay one big, where content is half priced. my vendor is not really hot on telling me for commercial reasons of course....




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one thing i would like to know: do we know a safe method to fill from a large tank into a small tank, using common plumbing and hardware? and how? typically I prefer to carry small bottles on the field

At NYPOWER a few years back we did tank transfers from K cylinders to chilled small 20# cylinders. We used a stainless steel braided line rated for the pressure to connect the tanks. This method got us about 75-80% of the small bottle filled 15# in a 20# tank. To get anymore than that requires a pump.
 
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I used to fill bottles by either putting them outside in the winter or in the freezer and then having the parent bottle nice and toasty. You could get it full by doing it a couple three times. Had to keep the pressure differential to make it work. It sucked! Finally found a used pump for a reasonable price and now I don't freeze my fingers any more. :)

First thing new hybrid fliers need to understand is that fact that a 20lb bottle has only 15 pounds usable at most! The top half of a bottle always works better. :)

Jason


At NYPOWER a few years back we did tank transfers from K cylinders to chilled small 20# cylinders. We used a stainless steel braided line rated for the pressure to connect the tanks. This method got us about 75-80% of the small bottle filled 15# in a 20# tank. To get anymore than that requires a pump.
 
Ok, here is how all the welding shops and speed shops that I have been dealing with for 10 years fill by bottle.

They put the bottle on a scale. Then they pump N2O into the bottle until the total weight = tare weight + 20#.

So I have 20# of liquid and vapor in the bottle. Taking the density chart, at 20C gas is about 18% by mass and liquid is 82% by mass. So I can expect to get 0.82*20 = ~16# of liquid N2O out of the bottle. In the motor tank I can then expect this to separate into vapor and liquid by the same ratio in the bottle.

Correct?
Everything is correct except for the last sentence as will be discussed below.

this fits exactly to my painfull experience of the past years. Take content in kg / 1.2 x 0,8 and you have really usable liter content for our hobby, as a simple rule of thumb.
When the sum of the volume of the motors fired with said same bottle achives the usable volume calculated above, change the bottle, do not even think more, especially for motors at J and more impulse. No way you can get the tank full next time. this means too you shall track what happens with the bottle, what motors you filled and what you plan next meeting if the bottle is not empty. just avoiding surprises.

one thing i would like to know: do we know a safe method to fill from a large tank into a small tank, using common plumbing and hardware? and how? typically I prefer to carry small bottles on the field but only pay one big, where content is half priced. my vendor is not really hot on telling me for commercial reasons of course....




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The pros use a high pressure liquid pump., but you don't need it for filling smaller bottles. Read below.

At NYPOWER a few years back we did tank transfers from K cylinders to chilled small 20# cylinders. We used a stainless steel braided line rated for the pressure to connect the tanks. This method got us about 75-80% of the small bottle filled 15# in a 20# tank. To get anymore than that requires a pump.
You do not need a pump, but you must fill with liquid.

1.) You must feed nitrous from a source tank with an educator tube or from an inverted cylinder to insure you are feeding liquid nitrous to the smaller transfer tank.

2.) If you do not have a liquid pump you should chill the smaller tank a few degrees below the source tank to insure a >10 PSI pressure differential between the source tank and the smaller tank.

3.) When you open the valve between the 2 tanks, the liquid will flow from the high pressure source tank to the lower pressure transfer tank. Since the transfer tank is colder than the source tank, any gas will be condensed into a liquid by higher pressure and lower temperature in the transfer tank. If the transfer tank is completely chilled (including the valving) there will be no gas within the tank, only liquid, and you could put 23 to 24 pounds of liquid nitrous into a tank rated for 20 pounds but you shouldn't. If you weigh the tank after filing and have more than the rate weight, you should vent the excess until the content is reduced to the rated weight to insure having sufficient ullage volume in the smaller tank.

One should never transport a liquefied gas in a tank without ullage (headspace) volume. If the liquid flashes to gas over the critical temperature, the tank could fracture.... Not good.

When you fill a vented tank with nitrous, you can also get 100% liquid into the vented tank. This is because some of the liquid evaporates as the tank is filled, reducing the temperature of the liquid. As you fill the vented tank, the gaseous nitrous is vented and the liquid gets cooler, until you eventually fill the tank completely with liquid. The tank will completely fill and the excess liquid will vaporize as it leave the vent, resulting in the atmospheric moisture created white plume you see from a filled vented hybrid tank.

Bob
 
I made some inquiries over the last week and a half, and have managed to draw out some old SkyRipper hardware and reloads. I will be receiving 29mm; 38mm and 54mm hardware and reloads over the couse of a week. Today the first loads showed up; I had been talking with Doug Pratt of Pratt-Hobbies about getting his GSE, and thought I would ask if he had any old stock of SkyRipper relaods... he did, and they arrived today (1) package ea of the polypro and PVC 38mm reloads and (3) packs of the 54mm reloads:

IMG_8142_zpsc37a0726.jpg


IMG_8141_zpsfbd1e61e.jpg


I have more 54mm, 38mm and a few 29mm reloads coming as well, plus the 3-complete systems that Todd developed over the years... I should be set for flights for a while.

My plan is to start silicone molding the reloads that are injected molded, so I can make my own reloads over time. More on that as I research more on the molding process and the plastics available, like polyurethane etc.
 
You lucky you :)
Now put them on eBay, you shall be a rich man *lol*

By the way, best regards to Doug ...I am still waiting for his GSE offer he promised me months ago *lol*...Maybe he reads this ;-)
 
Dennis, I have a question for you. On your 3 motor cluster flights, how to you tell if all three motors are full? Do you bring your vent tubes to one side of the rocket so you can see them all at one view?
 
You lucky you :)
Now put them on eBay, you shall be a rich man *lol*

By the way, best regards to Doug ...I am still waiting for his GSE offer he promised me months ago *lol*...Maybe he reads this ;-)

He is working on upgrading his GSE to add additional funtionality like a timing circuit etc. This requires the use of Cat5e cable, which I am glad he is going away from phone cable.
 
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