Why not hybrids?
- Thread starter karlbaum
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There are any number of ways to make the grain, as ABS rod is available in many sizes... you just need the lathe and bits.
Where milling capabilities end, the 3D print takes advantage of... and that is that grain geometries can be manipolated.
kramer714
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Hybrid fun this weekend at ROCstock, Lucerne Dry Lakebed
Perfect weather, zero wind, yup, like not any wind, 35 at night 80 in the afternoon.
In addition to a solid, I launched, RATT I-90, RATT K240, Contrail M1492
Ratt I90 quick to setup, as easy as an Aerotech solid. On a 48inch long graphite rocket, this one tapers from 29mm at the base to 60mm at the top, ideal for a long skinny hybrid.
RATT K240, this is my new FAVORITE motor, it is the loudest motor I have ever heard, 6,800 feet on a 4" diameter rocket. Almost no flame but plenty of noise
Contrail M1492, nice long very stable rocket, actually did a tail slide at apogee, Contrail is the fasted to ignite hybrid, push the button and it goes.
That's why hybrids! Oh, and 'the boy' is now the official photographer in addition to being the ground crew.
Mike K
Perfect weather, zero wind, yup, like not any wind, 35 at night 80 in the afternoon.
In addition to a solid, I launched, RATT I-90, RATT K240, Contrail M1492
Ratt I90 quick to setup, as easy as an Aerotech solid. On a 48inch long graphite rocket, this one tapers from 29mm at the base to 60mm at the top, ideal for a long skinny hybrid.
RATT K240, this is my new FAVORITE motor, it is the loudest motor I have ever heard, 6,800 feet on a 4" diameter rocket. Almost no flame but plenty of noise
Contrail M1492, nice long very stable rocket, actually did a tail slide at apogee, Contrail is the fasted to ignite hybrid, push the button and it goes.
That's why hybrids! Oh, and 'the boy' is now the official photographer in addition to being the ground crew.
Mike K
legranddudu
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Great!
Congrats for the perfect hybrid flights!
Denis
Gesendet von meinem iPad mit Rocketry Forum
Congrats for the perfect hybrid flights!
Denis
Gesendet von meinem iPad mit Rocketry Forum
Nice pics, would love to have a flying weekend like that. You are right about the RATT K240 being loud... she screams!
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Well, I took the first small "official" step back into hybrids. I'm seeing about ordering the combustion chamber and nozzle portion of a little EX 76mm 25%M989 with three injectors for a little MD project I'm calling THRP-1 (Tiny Hybrid Rocket Project - 1). The motor is close to 5' long in the full configuration though it can use smaller tanks. The fins are BinderDesign MaxQ fincan that clamps to the combustion chamber. Recovery and electronics will bolt to the top of the motor. everything below is bare metal. It's a bit minimalist. Overall length is in the ballpark of 7', final length TBD as I've got multiple configurations in mind and I'd like to squeeze in a video camera. Altitude expected around 21Kft (design target), speed around Mach 1.55. I'll be ordering the squared tank tube in the next few weeks most likely. I plan to machine the forward bulkhead and the injector assembly myself.
Design work was done using the Hybrid Design Spreadsheet by Todd Moore of Sky Ripper Systems, which produced simulation that I copied into a motor file and used in RasAero for the flight simulation. For non-hybrid rockets, using other methods of generating thrust curves, into RasAero, I'm generally less than 3% error at the worst. Hybrids though are a fairly new realm for me and the uncertainty is much greater when working with N2O. To deal with that, the nitrous is intended to be at a controlled temperature of 40F. I think I know of two or three ways to achieve this, but for initial testing I'll likely not bother. Heck, the weather around here is likely to make that about right for a static test.
I'll provide more info about the project later on, as it gets under way. I've played with this sort of design for a few years now. I'd originally intended to do my L3 cert on a similar rocket but in the end went with a different approach. I've wanted to go back and do the rocket - well, this is it, with updates of course. It might make an appearance at LDRS next year. We'll see.
Gerald
Design work was done using the Hybrid Design Spreadsheet by Todd Moore of Sky Ripper Systems, which produced simulation that I copied into a motor file and used in RasAero for the flight simulation. For non-hybrid rockets, using other methods of generating thrust curves, into RasAero, I'm generally less than 3% error at the worst. Hybrids though are a fairly new realm for me and the uncertainty is much greater when working with N2O. To deal with that, the nitrous is intended to be at a controlled temperature of 40F. I think I know of two or three ways to achieve this, but for initial testing I'll likely not bother. Heck, the weather around here is likely to make that about right for a static test.
I'll provide more info about the project later on, as it gets under way. I've played with this sort of design for a few years now. I'd originally intended to do my L3 cert on a similar rocket but in the end went with a different approach. I've wanted to go back and do the rocket - well, this is it, with updates of course. It might make an appearance at LDRS next year. We'll see.
Gerald
Cool thread! I have some old SRS 38 and 54 motors and I think I have reloads for them still. I was saving at least one of each for exactly this use, EX Hybrid. I wish I could just buy them, they weren't very expensive. I even have the GSE, though some of it needs repairs. Guess I need to renew my Trippoli membership.
Dragon64: I'm very interested in hearing about how your 3D-printed grains do!
Dragon64: I'm very interested in hearing about how your 3D-printed grains do!
I have not heard back from anyone that I passed files to. My work place gave me reservations about why I am not allowed to use their makerbot to print a few grains, so I will not be able to print my own. However, I am looking at rapid proto-typing using silicone molds.
One of the worries I have with some 3D printers, is how porous a product might turn out to be.
I'm a long way off from flying... I have a few kits to build and a rocket or two to modify to take on the hybrid motors, and I am lacking severely in the GSE department... with Christmas nearly here, it is getting tougher to save coin for anything further just yet. I'm hopeful for a nice start to the Spring flying season in 2015.
