Issus
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- Aug 27, 2012
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I got kinda bored on Friday night, so I drew this up - it actually ended up taking me about 1.5 days to do.
If Arnold Schwarzenegger played Frisbee, this is what I imagine he'd play it with. It's a 800mm diameter, carries 12x D or E black powder motors to spin it up, and can take up to 6x 38mm main boosters.
I've designed the whole thing to be milled out of 70mm thick polystyrene sheet. I broke it up into chunks so it will be less effort to make jigs to hold the parts for double sided work, I've also designed it to be fully millable using a 10mm ball nose end mill, because I'm lazy and cant be bothered switching tools. The plywood parts are millable with a 3mm endmill, and the plastic is 3d printed (I'll likely actually print 1 at super high res then make a silicone mould for making the rest out of urethane).
I ended up with 6 motor mounts, because I couldnt decide between two or 3. They are also 38mm because I couldnt decide between 24 and 29mm motors. This may seem illogical, but when you think about it, "the more the merrier" and "bigger is better" riiiiiggght? Actually, with 6 places, I can launch with 2, 3, 4 or 6 motors mounted and retain symmetry. Likewise, with a 38mm grain, it doesnt really cost very much more than a 29mm load however is shorter. The motor mount tubes in this are 200mm long, a 4 or 5 grain CTI 29mm isnt much longer than a 2 grain 38mm and has similar amounts of propellant, sooo why not go the larger motor mount and allow it to be adapted down. At this point, i'm thinking I'll try to fly this exclusively on sparky motors, and only on CTI - the black powder/pyrodex grain in them gets them going so much more reliably than the aerotechs do. This is my first clustered rocket btw, with 18 motors!
I'm using black powder for the rotational motors, as they will come up faster than the central composites which will begin spin stabilisation before the rocket starts moving upwards. I mounted them on top because I think it looks cooler. This frisbee has been designed for aesthetics as I see them, rather than for performance... this style of rocket wont really have much performance but will look cool! I have a feeling that there are too many rotational motors, without any drag consideration i'm looking at about 15,000rpm - so I guess i'll get more like 2000-5000rpm with all motors firing - this is likely to be too high.
I'm planning to use a 1" pvc pipe as the launch rail/rod, with the bushing for it being made out of fibreglass using the pipe as a mandrel. I have 3 pockets on the hub which have doors on them so I can hold batteries for lighting, or avionics for staging. This would allow me to stage the rim motors and/or the main motors. I'm tempted to make the second set of rim motors fire at apogee to spin it up faster.
For a launch system, I'll likely need to use a large relay and a decent sized LiPo battery at the pad, as our launch system uses power cords and a car battery at the LCO's desk to provide power. The power requirements of this will be considerable.
The vanes on the fan are NACA N6409 9% airfoils, simply because I thought it looked good for a fan blade *shrug*.
I'm not planning to start work on this yet, I have a few too many other projects going on which I'd like to get finished, however I would like to launch this on June 1 so I don't have too long before I need to start milling test pieces to check the feasibility.
Thoughts, ideas and questions are always welcome
If Arnold Schwarzenegger played Frisbee, this is what I imagine he'd play it with. It's a 800mm diameter, carries 12x D or E black powder motors to spin it up, and can take up to 6x 38mm main boosters.
I've designed the whole thing to be milled out of 70mm thick polystyrene sheet. I broke it up into chunks so it will be less effort to make jigs to hold the parts for double sided work, I've also designed it to be fully millable using a 10mm ball nose end mill, because I'm lazy and cant be bothered switching tools. The plywood parts are millable with a 3mm endmill, and the plastic is 3d printed (I'll likely actually print 1 at super high res then make a silicone mould for making the rest out of urethane).
I ended up with 6 motor mounts, because I couldnt decide between two or 3. They are also 38mm because I couldnt decide between 24 and 29mm motors. This may seem illogical, but when you think about it, "the more the merrier" and "bigger is better" riiiiiggght? Actually, with 6 places, I can launch with 2, 3, 4 or 6 motors mounted and retain symmetry. Likewise, with a 38mm grain, it doesnt really cost very much more than a 29mm load however is shorter. The motor mount tubes in this are 200mm long, a 4 or 5 grain CTI 29mm isnt much longer than a 2 grain 38mm and has similar amounts of propellant, sooo why not go the larger motor mount and allow it to be adapted down. At this point, i'm thinking I'll try to fly this exclusively on sparky motors, and only on CTI - the black powder/pyrodex grain in them gets them going so much more reliably than the aerotechs do. This is my first clustered rocket btw, with 18 motors!
I'm using black powder for the rotational motors, as they will come up faster than the central composites which will begin spin stabilisation before the rocket starts moving upwards. I mounted them on top because I think it looks cooler. This frisbee has been designed for aesthetics as I see them, rather than for performance... this style of rocket wont really have much performance but will look cool! I have a feeling that there are too many rotational motors, without any drag consideration i'm looking at about 15,000rpm - so I guess i'll get more like 2000-5000rpm with all motors firing - this is likely to be too high.
I'm planning to use a 1" pvc pipe as the launch rail/rod, with the bushing for it being made out of fibreglass using the pipe as a mandrel. I have 3 pockets on the hub which have doors on them so I can hold batteries for lighting, or avionics for staging. This would allow me to stage the rim motors and/or the main motors. I'm tempted to make the second set of rim motors fire at apogee to spin it up faster.
For a launch system, I'll likely need to use a large relay and a decent sized LiPo battery at the pad, as our launch system uses power cords and a car battery at the LCO's desk to provide power. The power requirements of this will be considerable.
The vanes on the fan are NACA N6409 9% airfoils, simply because I thought it looked good for a fan blade *shrug*.
I'm not planning to start work on this yet, I have a few too many other projects going on which I'd like to get finished, however I would like to launch this on June 1 so I don't have too long before I need to start milling test pieces to check the feasibility.
Thoughts, ideas and questions are always welcome