Show us your hybrid

Discussions on hybrid rocketry including rockets, motors and technologies.

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hybridhighflyer
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Re: Show us your hybrid

Postby hybridhighflyer » Thu Oct 06, 2011 9:06 am

Contrail M 2200 is 20 inches shorter lol and only 75mm.

Impressive though for a ratworks

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Re: Show us your hybrid

Postby strud » Thu Oct 06, 2011 9:56 am

Wayne

What isp and total impulse does the M2200 achieve ?

CS

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Re: Show us your hybrid

Postby hybridhighflyer » Thu Oct 06, 2011 10:27 am

You have 3 choices

M2281 - TI-5482 PT-6040 AT-2252 BT-2.14s
M1673 - TI-5675 PT-5075 AT-1693 BT-3.35s (another 4 inches smaller)
M762 - TI-5507 PT-1872 AT-762.44 BT-7.33s

I believe they are cheaper too.

For me this is all from 1 peice of hardware and it can run 18 different motors. So huge value for money.

Again this is all preference would gladly lend you the hardware as long as you dont break it :P

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Re: Show us your hybrid

Postby cha05cat » Thu Oct 06, 2011 1:58 pm

The issue there is that the Contrail M2281 and the RATT M900 are very different motors. In that the M900 is a significantly longer burn at 12.1 seconds vs 2.1 seconds. Plus the M900 has a higher total impulse of 6463Ns vs 5482Ns. The extra length containing the additional 500cc on Nitrous is what gives it a higher total impulse. Sorry, I thought that as a "hybrid expert" you would have already understood this though...

Strud: I must say that L600 was an awesome launch!
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Re: Show us your hybrid

Postby hybridhighflyer » Thu Oct 06, 2011 3:04 pm

F=M*A

Bigger motors and higher force dont mean higher launch....

I thought you were a rocketry expert......

the mass from 20-24 inches of motor as well as heavier take off weight and the body tube and frame and other matirials would also be added weight. I havent done the math but this takes a lot from the motor's benifits.

To be dead honest if you were worried about height you would never use a hybrid motor they are heavy in most cases. So the increased thust of 1000N's and the cost of the motor having to be purchased every time and building a kit just for it whats the real benifit....

Yes Contrail is a faster burn but its slimmer, lighter as mass is reduced faster, its faster speed for cheaper cost and in my opinion a better system. You dont have to build a rocket kit just to fit it as well.

So when you make the assumption I havent thought about it well.... I have, maybe its you that hasnt got your mind past the 1000N's insted of thinking of what makes a rocket and what rocket costs are. I am not saying there is no height benifit to be gained from the motor what I am saying is ....is it worth it. My answser is Contrail is more worth it in many ways.

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Re: Show us your hybrid

Postby cha05cat » Thu Oct 06, 2011 3:25 pm

Ummmm.... Yeah.... right.....

Anyhoo, yes costs are a big thing to me.

When the RATT system for both the L600 and M900 costs $375 and the case for the M2281 is $825 - I think that almost speaks for itself...
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hybridhighflyer
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Re: Show us your hybrid

Postby hybridhighflyer » Thu Oct 06, 2011 3:35 pm

The hardware.... Harware lasts forever pretty much and the contrail quallity cant be matched.

I mean launching... how much extra nitrus is 24 inches of tube's?

How much for 64mm tubing as its non standard and how much for the extra matirials and then getting the CP and CG right.

With this system you make the rocket for the system, Not make the rocket and use that motor.

Again this is difference of opinion. Its what you want.. simply no use arguing but I am just posting the differences.

The best I got from my real kits that have flown in rocksim is a extra 3000 ft on this motor. Thats with no room for parachutte or anything else. Add the extra length needed and you most likely would reduce that to 1000-2000 ft.

I like fast burning motors and with hybrids height is never the goal in my opinion. I can get mach 2.4 on this motor,

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Re: Show us your hybrid

Postby rocket_troy » Thu Oct 06, 2011 4:04 pm

hybridhighflyer wrote:F=M*A

Bigger motors and higher force dont mean higher launch....

I thought you were a rocketry expert......

the mass from 20-24 inches of motor as well as heavier take off weight and the body tube and frame and other matirials would also be added weight. I havent done the math but this takes a lot from the motor's benifits.



Maybe if your propellant's Isp was extremely low... and that "maybe" being attached with a myriad of caveats, disclaimers, provisos and lotto jackpot likelihoods.

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hybridhighflyer
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Re: Show us your hybrid

Postby hybridhighflyer » Thu Oct 06, 2011 4:21 pm

Rocksim may not be accurate but my sims havent lied to what I am trying to say.

I don't see the huge benifits of this motor. 3000ft on a already 15000ft launch is a 1/5th boost to something which I see has a lot of costs.

AGAIN - Its what you want out of it... I dont like slow burning motors.

Then again few reading this would take our chat compared to a real dragrace between the 2 ;) Which should be arranged!!

Even though I cringe when I say this both motors and motor systems are good. They both have the benifits however for me its what I see or how fast it dissapears that matters. I get more thrill out of going fast, going mach and seeing a good flame. 15000-18000 ft wont do much for me.

If you want pure height and a slow motion lift off get the M900 if you want to see how fast a 10kg rocket can dissapear with sparks and be told it either disintagrated or went mach 2 get mine.

To be honest I would try the other rocket motor myself and maybe buy it. Being a contrail distributor I may be bias ;)

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Re: Show us your hybrid

Postby Lamp » Thu Oct 06, 2011 4:52 pm

Everyone has different goals and enjoys different aspects of rocketry and that is why there is a range of average impulse motors. I don't fly hybrids but I enjoy the nice slow liftoff and boost that some rocket/motor combinations give just as much as the high speed launches that other combinations give. :wink:
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Re: Show us your hybrid

Postby OverTheTop » Thu Oct 06, 2011 6:30 pm

Sounds a bit like some "skiers" vs "snowboarders" arguments that some people get into. In my opinion whatever way they want to get down the hill is fine!

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Re: Show us your hybrid

Postby PK » Thu Oct 06, 2011 10:40 pm

Sigh.... Just to confirm what everyone suspects, not much of what Wayne has posted here stands up to inspection. (let alone a spell check)...
Troy (a die hard solids guy) has flown as many hybrid flights as just about anyone. If you consider that his average hybrid launch is an L or M then you could do worse than to pay attention to what he says.
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Re: Show us your hybrid

Postby strud » Fri Oct 07, 2011 1:31 pm

What happened here ?

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Re: Show us your hybrid

Postby strud » Fri Oct 07, 2011 3:57 pm

Some things to consider
- adding 'mass' whilst maintaining diameter & drag will often increase altitude (unless you are already over optimum)
- A vented hybrid motor will never perform the same twice
- Published N2O hybrid motor performance numbers are usually rather generous or at least best case
- A self pressurising N2O hybrid will perform dramatically differently as ambient temperature changes. I motor rocket combination of mine has flown to 10500ft in one instance (cold day) and about 3500ft on another instance when the N2O got up to near 30degC. Even though the vapour pressure was up near 900psi, the density had dropped off dramatically giving incredibly poor performance.

CS

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Re: Show us your hybrid

Postby cryoscum » Fri Oct 07, 2011 4:41 pm

I remember "Misery in a can"! Love the noise the hybrids make. Nice flight, Strud!
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Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns


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