Hybrids 2021

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Dave A

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Hi Dave,

In Centreville VA here - can one get a larger tank filled? Can a stranger get one filled or only somebody they know? Will they do the cleaning for oxidizer service? I'll get a tank if I can get it filled and that price sounds quite nice.

Gerald
Sorry, for the slow reply.
I look at RF once a day or so.
Anyone that comes to the track can get 2-10# bottles filled vendor by the comes to our races.
My 20# was half full and he topped it off for me. In the motorcycle drag racing world, 5# bottles are the largest bikes run. They don't bring enough to fill big bottles.
I do not know where to get the larger ones filled. I think the track management fills them
Will Roberts Oxygen sell/lease NO2 cylinders? I've dealt with them with other gases but not NO2.
 

Dave A

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Darn, haven't looked at my bottle yet to see if the hydro is out of date or not.
We ALWAYS had to have our scuba tanks hydro'd. You dive at the springs in FL, they'll give you what I call is a hot fill at 3200. Trust me I never asked for it.
 

ContrailRockets

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I think the point dhbarr was basically making was the primary reason why pressure vessels are hydrostatically tested (as opposed to pneumatically tested) is safety. Because liquids are practically incompressible (at the pressures we're dealing with) the only energy contained within a fully pressurized cylinder (filled with liquid) would be the elasticity of the cylinder itself as opposed to a pneumatically pressurized cylinder, so if there was a structural failure, the outcome is quite benign as opposed to something extremely & dangerously spectacular.

TP
Hydro testing of 152 mm snap ring test cylinder to failure of +3200psi. Used oil not water as have 10,000 psi oil pump but was cool to see design of 3,000 psi held. NFPA requires only a 2000 psi test of a 3,000 psi design but I like to error on the safe side. Ok the duct tape may not work but?????
7593E9A1-294D-47E5-AFB6-143592641F06.jpeg
 
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Dave A

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Hi Dave,
In Centreville VA here - can one get a larger tank filled? Can a stranger get one filled or only somebody they know? Will they do the cleaning for oxidizer service? I'll get a tank if I can get it filled and that price sounds quite nice.
Gerald
Gerald, will you be at Culpeper this weekend?
Dave
 

G_T

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I hadn't thought about it actually. I haven't set up anything to fly or test. Generally I've been avoiding collections of people.

Gerald
 

Dave A

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I hadn't thought about it actually. I haven't set up anything to fly or test. Generally I've been avoiding collections of people.

Gerald
I've been staying alone in the trailer. I stay masked and now have all my shots. This my last for the year for me.
 

G_T

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I haven't cast a fuel grain or preheater for the EX hybrid yet, nor gained permission for another static test. Or for that matter made arrangements for N2O. I can make a grain and preheater in an evening, but there probably isn't time for the rest. So unless someone is already going to be there with at least 12# of nitrous to waste, I probably won't be there. I'd love to perform another static burn as I didn't get much usable data from the first test due to the delay in going to complete ignition, but I don't have all the ducks lined up at the moment. So if someone is going to be there with nitrous to burn, shout quickly!

So I probably won't be there unless Jerry and I make a static burn there as part of our series of tests towards his current Black Rock project.

Gerald
 

ContrailRockets

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NOS valves are the CGA-326 .125 orfice for small tanks and the CGA-660 .187 orfice for industrial cylinders.
Well some of us want to move NOS Faster
This High Flow NOS cylinder valve can do just that with a .311 seat orfice and a .345 outlet fills can be faster. This valve makes sense if you are using the .375 orfice CFF solenoid valve.
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kramer714

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My NOS supplier for years has told me that I need to be using ONLY CGA-660. About a year ago he told me he could only fill tanks with CGA-660 on them NOT 326 to be legal. Not sure if this is a California thing or because he is ONLY selling for cars, not medical. If you are sourcing / buying / retrofitting, I would call your supplier and find out what they recommend.
 

jderimig

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My current will hook up to 660 or 326. My previous supplier only had 660 fittings so I had to bring my 326 to 660 adapter.
 

ContrailRockets

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typical you find the following
CGA-326 is for medical NOS
CGA-660 is for industrial NOS for safety sulfur dioxide is added.
Some locations have the ability to get medical NOS if they have a Doctor involved.
 

G_T

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What is the percentage SO2? Just enough trace to smell, or higher?
 

rocket_troy

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In some places like Australia, there is no difference ie. no denaturing agent introduced into the engine boosting grade.

TP
 

Bruce

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Newbie question:

Could someone please tell me what CNVA stands for? What exactly this is and what it is used for?

Just getting started and trying to understand the terminology. If there's an appropriate document, please forward a link.

Thanks!
 

dhbarr

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Bruce

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Thanks!

Another question,

Would G hybrid motors be considered within the FAA Class 1 category of using no more than 125 grams of propellant?
 

ContrailRockets

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Thanks!

Another question,

Would G hybrid motors be considered within the FAA Class 1 category of using no more than 125 grams of propellant?
Since this motor exceeds 80 Newton’s it requires a FAA waiver. This creates the requirement that you be 18 years of age. TRA and NAR both have safety codes in place and are the best place to find a waiver and fly hybrids.
 

Bruce

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I thought the 80 Newton Average Thrust limit was a Tripoli or NAR restriction.

Here's a page listing the FAA CFR 101.22,

https://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&node=14:2.0.1.3.15

which says:

Class 1—Model Rocket means an amateur rocket that:
(1) Uses no more than 125 grams (4.4 ounces) of propellant;
(2) Uses a slow-burning propellant;
(3) Is made of paper, wood, or breakable plastic;
(4) Contains no substantial metal parts; and
(5) Weighs no more than 1,500 grams (53 ounces), including the propellant.


Nothing is mentioned about Average Thrust or 80 Newtons.

So do G Hybrids use less than 125 grams of propellant?
 

ContrailRockets

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As the Motor Manufacturer I defer to NFPA 1127 and the Tripoli Safety Code.

High Power Rocket Motor. A rocket motor that has more than 160 newton-seconds of total impulse or an average thrust greater than 80 newton-seconds and that otherwise meets the other requirements set forth in this code.

The FAA standard refers to slow burning which the NFPA 1127 sets at below 80 newton-seconds. The Contrail Rockets G-100 is a High Power Rocket motor not a Model Rocket Motor. This means that as stated in the Contrail Rockets 38mm Hybrid Rocket Motor Reload Instruction Manual, that the Tripoli Safety Code as well as the NFPA Safety Code are to be followed. This includes that the person shall be at least 18 years of age.

In NFPA 1127 Chapter 6 Prohibited Activities. Sub section 6-1 (e) states the following "The operation, discharge, or activation of a high power rocket contrary to the provisions of Federal Aviation Administrations regulations.

In addition in the Tripoli Range Safety Guidelines under Flight Safety Review by the Flight Safety Officer FSO page 15


o Rockets powered by rocket motors not classified as model rocket motors per NFPA 1122, e.g.:
 Average thrust in excess of 80.0 Newtons  Total impulse of 160.01 Newton-seconds or more
 Contains in excess of 2.2 ounces (62.5 grams) of propellant
Hybrids (regardless of impulse)

With this standard in place if a Contrail Rockets motor with less than 160 newton-seconds of thrust were certified with less than 80 newton-seconds of thrust, they would still fall under the safety standards set for High Power Rocketry and be controlled by an RSO and FSO.


I am happy to have TRA and NAR overseeing our hobby to keep it safe.
I am happy to pay dues which helps to cover liability insurance at sanctioned launches.
 

Bruce

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Agreed. All hybrids and motors with greater than 80 Newtons of thrust are considered High Power and will require High Power Certification.

But there are launches where the rules specify that any rocket flown must meet the FAA Class 1 rules, one of which is requiring the use of no more than 125 grams of propellant. High Power G motors are permitted at these launches, IF the flyer has Level 1 or higher certification with Tripoli or NAR.

But probably the weight of the Nitrous Oxide plus the Fuel grain for any hybrid will end up being over 125 grams anyway, so it doesn't really make any difference.

I just thought that smaller rockets could be an area for hybrids to branch into.
 

ContrailRockets

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Agreed. All hybrids and motors with greater than 80 Newtons of thrust are considered High Power and will require High Power Certification.

But there are launches where the rules specify that any rocket flown must meet the FAA Class 1 rules, one of which is requiring the use of no more than 125 grams of propellant. High Power G motors are permitted at these launches, IF the flyer has Level 1 or higher certification with Tripoli or NAR.

But probably the weight of the Nitrous Oxide plus the Fuel grain for any hybrid will end up being over 125 grams anyway, so it doesn't really make any difference.

I just thought that smaller rockets could be an area for hybrids to branch into.
G-100 off top of head is 115 grams NOS and fuel. In the 29 mm line have smaller motors designed and tested but not released.
Your question made me research beyond NFPA 1127 and Tripoli Safety to find the all hybrid restriction. RSO and FSO oversight on hybrids adds another level of safety for flyers and spectators. I may dust off the 29 mm and put them back on the test stand that is if enough flyers are interested in 29 mm hybrid motors. Right now the 54 mm internally vented CNVA injector pleated grain 11.25 long hybrid motor with 250 cc of NOS is a testament that hybrid R&D has not stopped.
I am presently working with the University of Trennessee to turn the 38 mm 16 inch G-100 into an I motor. They have more than doubled the motors performance getting a full H motor out of that case. I am adding several additional modifications including an internal vent which may get us the Newton’s needed for an I motor.

The only limitation is your imagination.
Tom
Contrail Rockets
Hybrid motors and more.....
 

AeroTech

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Just for fun read the AeroTech pre filled Hybrid manual. The Safety section recommends leather gloves filling and purging tank to get cold enough for filling to occur the critical need not to over fill. Weight is critical. Also noted is the potential of accidental ignition if the Pyro seal breaks or if contaminated Grease is introduced. Motors once at 75 degrees are to be assembled at the pad, ensure that you are not in the nozzle flame path or that the rupture valve is pointing away from you while wearing your leather gloves. Install assembled motor into rocket then when vertical and only then install the electric match which has masking tape in a small cup filled with black powder and pinched at the top. Using the supplied guide insert into motor until one inch of guide is exposed instal motor cap which has been cut to the nozzle and tape in place.
In the event the motor fails to fire they recommend that you get your leather gloves and remove and disassemble the motor starting the process over.
Pad filled motors using remote fill do not require fill and purge as they purge thru the vent which in many cases is thru the combustion chamber. More importantly you are never near a motor that could release pressureized NOS or worse ignite during assembly or disassemble.
The remote pad fill system is faster and safer as I can prebuilt motors before a launch. Have them loaded and secured in a rocket install on rail hook up fill and fire connection with no risk.
In a 440 cc hybrid motor I can fill it during the five second count down. Facts not just my opinion.
The safety section of the manual was written in a very conservative fashion, since hybrids were new to the hobby back then and no one had experience with them.

Prefilled N2O tanks are used all the time. Automotive and medical applications for example. Even vented systems use a prefilled tank to fill the flight tank.

I’m approached often at launches by flyers who lament the discontinuing of the AeroTech hybrids, who tell me they were the best ever made.

They are still being flown, and I saw two flights at AirFest last year, one standard and an EFX reload. Both flights were perfect.
 

ContrailRockets

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I believe that the best pre filled hybrid motors were manufactured by AeroTech. I think the limitations that Hypertek had in thier larger motors is consistent with any threaded tank to combustion chamber. The Trojan adapter saw the same limitation NOS flow is restricted in the connection between the flight cylinder and the combustion chamber. Additionally increasing the injector size and or quantity is easier in a motor having a floating bulkhead or bolted injector baffle as in Contrails larger motors.
 

G_T

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IIRC, didn't one drill out the passage to increase the NOS flow? Again, within limitations!
 

crossfire

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I’m getting ready to do a demonstration launch of this new Contrail Rockets 54mm x 20” hybrid motor in my new CF-modified Apogee Peregrine, hopefully at the next Big Sky Rocketry Association launch on April 17th.
Did you get to fly the hybrid?
 
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