Show us your hybrid

Discussions on hybrid rocketry including rockets, motors and technologies.

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Andrew Burns
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Re: Show us your hybrid

Postby Andrew Burns » Fri Oct 07, 2011 5:25 pm

As has been mentioned, I've made a simple time-variant computer model of a self pressurised nitrous hybrid including (again simple) nitrous boiling and physical properties. After the case Strud mentioned I did several simulations of the same hybrid with initial nitrous temperatures from 15 to 32 degrees C. The model showed an increase of about 10% in average thrust between 15 and 32 but a decrease in total impulse of over 25% with increasing temperature. Liquid phase burn time dropped from 9.47 seconds in the first case to under 5.9 seconds in the final case. Additional the model doesn't account for nitrous density stratification, changes in ullage volume or increase in two-phase flow at the injector between the cases which would make the effects of temperature even more dramatic.

So as Strud said, no self-pressurising nitrous hybrid will perform the same way twice simply because at the pressures we generally want the temperature of the nitrous is so close to its critical point that even slight variations cause dramatic shifts in density. Additionally I've heard some conjecture about the way hybrids are tested for certification (in regards to the state that the nitrous is in before the tests) so I'd take commercial hybrid thrust curves and total impulse values with a grain of salt unless personally verified on a test stand.

jeff jakob
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Re: Show us your hybrid

Postby jeff jakob » Sat Feb 11, 2012 2:40 pm

One of our hybrid rockets getting prepped for flight at Black Rock
http://www.youtube.com/watch?v=mK3JCzMddLU

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Re: Show us your hybrid

Postby rocket_troy » Sun Nov 25, 2012 10:53 pm

Some photos thanks to David Wilkins and Pete Pam of my 90mm postpak rocket hybrid rocket in action this year and from October last year from Serpentine:

Photo from March this year (David Wilkins photo):
Image

Ground shaking November Launch (David Wilkins photo):
Image

October 2011 (David Wilkins photo):
Image

Red Flame fuel this year (David Wilkins photo)
Image

Red Flame fuel this year (Pete Lam photo)
Image

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Re: Show us your hybrid

Postby Passaretti » Mon Nov 26, 2012 2:45 am

Nice shots! Thanks for sharing Troy!
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Re: Show us your hybrid

Postby october sky » Mon Nov 26, 2012 4:03 pm

Very nice indeed ! 8)
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Re: Show us your hybrid

Postby jase » Mon Nov 26, 2012 5:59 pm

I can confirm the seismic event at the November launch - STUNNING!
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Re: Show us your hybrid

Postby rocket_troy » Mon May 19, 2014 1:15 pm

Dave Pratt just sent me a frame grab from a video he took of my 2nd April Hybrid launch.

Image

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Re: Show us your hybrid

Postby strud » Mon May 19, 2014 3:11 pm

Great pics Troy :-)

Here's a couple of mine from some years ago...

Image

Image

Image

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Re: Show us your hybrid

Postby rocket_troy » Mon May 19, 2014 3:28 pm

strud wrote:Great pics Troy :-)

Here's a couple of mine from some years ago...

Nice. Have you dusted off any since the shift?

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Re: Show us your hybrid

Postby strud » Mon May 19, 2014 9:43 pm

Yes got some of it out for a look-see

Will be launching a Rattworks L600 in Williams shortly if all goes well, but have another project we hope to get off the ground later in the year.

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Re: Show us your hybrid

Postby 03flyer » Sat May 12, 2018 8:09 pm

Last post was 2014...
SHOW ME YOUR CURRENT HYBRID.
Pics (if possible) with full details will be appreciated.
Go big or go home

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Re: Show us your hybrid

Postby drew » Mon May 14, 2018 10:58 am

03flyer wrote:Last post was 2014...
SHOW ME YOUR CURRENT HYBRID.
Pics (if possible) with full details will be appreciated.


I think there's a reason for this 03flyer... To my knowledge there are very few out there that are still playing with hybrids.

I own a RATTworks J160 and it does an excellent job of collecting dust.
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Happy Heyoka
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Re: Show us your hybrid

Postby Happy Heyoka » Mon May 14, 2018 5:11 pm

drew wrote:I own a RATTworks J160 and it does an excellent job of collecting dust.


is there something specific that bugs you about them?

the two things that I wonder about are:
(1) it seems somewhat a pain in the bum to lug around gas (& accessories, rental of cylinder etc)
(2) there appears to be a lot more to go wrong with launching them (getting on for 30% or 40% failure rate?)

that said, they're pretty awesome when they work...
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drew
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Re: Show us your hybrid

Postby drew » Mon May 14, 2018 6:04 pm

My problems are more practical.

1) I have no GSE.
2) I have no nitrous oxide.

I did try to do a static test of a MicroHybrid I also own. What a cf. I've never put together an Aerotech 18mm reload but I can't imagine it would be worse or more fiddly than a MicroHybrid.

I picked up the J160 from Aerocon when I attempted to source other RATTworks hybrids. The J160 was the only motor left on the shelf. IIRC I've got 1 grain so at best I'd be able to squeeze 2, maybe 3 flights out of it before needing someone to turn down another fuel grain.
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Re: Show us your hybrid

Postby lorstin » Tue May 15, 2018 8:45 am

drew wrote:........... IIRC ...........


WDTM :?
IAAH


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