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Post by Pttg on Nov 17, 2018 2:15:50 GMT
So I noticed that a VCS flywheel can easily reach greater than 9km/s rotational velocity at the edge. Using a few dozen wheels at incrementally higher rotational velocities, we could have launchers that are effectively hypersonic pitching machines. The wheels themselves could store energy, meaning that a low-energy system could gradually build up speed which is then reduced when the projectile is accelerated.
Advantages: High speeds despite low power draw. Moderate material demands. Stable. Efficient.
Disadvantages: Mechanical complexity. Large size and high mass.
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Post by airc777 on Nov 17, 2018 2:41:40 GMT
What about the sudden stress of the projectile at rest interfacing with the very edge of the already spun up flywheel to be accelerated to firing velocity? I think you’d probably have to stop and restart the flywheel after each shot to avoid shattering it. You could possibly achieve that with some regenerative braking with a second flywheel and a clutch. I don’t think centerfugal catipults are more accurate or mass efficient then railguns or the US navy would currently be testing them instead of railguns. Plus you’d have to model greater potential inaccuracy in the plain perpendicular to the axis of rotation due to mechanical inaccuracy with projectile release timing to accurately represent current state of the art recreational pumpkin throwing centerfugal catipults.
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Post by Pttg on Nov 17, 2018 3:27:50 GMT
The stress of accellerating the projectile is diminished by using a series of wheels. Think of a pitching machine, not a trebuchet.
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Post by airc777 on Nov 17, 2018 4:20:03 GMT
Oh, I thought you meant these things. m.youtube.com/watch?v=iH-KGJmvxjQA baseball pitching type machine throwing a projectile at 8 km/s would cause colossal acceleration stress to the projectile as the projectile is only being accelerated over the distance where the counter rotating wheels are nearly touching. It would be like having a a 8 km/s railguns with a 2 cm long barrel. Unless your intent is to have a long chain of these flywheels gradually accelerating the projectile? That sounds like it would make the launcher massive. |
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Post by linkxsc on Nov 17, 2018 5:05:45 GMT
>VCS flywheel can easily reach greater than 9km/s rotational velocity at the edge.
That seems a touch high. When I calculated it way back I was getting ~1400m/s for VCS. What... equation are you using to calculate this? And I believe the term you're looking for is tangential velocity or linear velocity, expressed in m/s (rotational velocity, or angular velocity is the number of degrees per second, rads/s, or rpm)
>Disadvantages: Mechanical complexity. Large size and high mass.
Why? Launch velocity in this case is actually independent of the diameter of the wheel being used to launch (assuming the wheel is spinning at yield or ultimate stress limit) A 10mm wheel will do just as well as a 1000mm wheel. Guess the motor would be pretty heavy as they scale poorly with small reaction wheels.
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Post by Pttg on Nov 17, 2018 6:37:15 GMT
I'm going by the flywheels used in turrets. The tangential velocity of those things gets to be insane.I built a 25-cm turret and figured out the diameter of the flywheel from there. I then figured out the circumference and RPS when it was spinning at the highest safe speed.
Wasn't sure if it was a reasonable design but the high max speed suggested it might be possible.
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Post by AtomHeartDragon on Nov 17, 2018 11:24:50 GMT
You could try feeding the projectiles near the hub and have them progress to the rim gradually. It would add a lot of complexity, though, and stress the wheel more.
Also, the launcher will be FUN if it's hit.
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Post by linkxsc on Nov 17, 2018 17:14:03 GMT
I'm going by the flywheels used in turrets. The tangential velocity of those things gets to be insane.I built a 25-cm turret and figured out the diameter of the flywheel from there. I then figured out the circumference and RPS when it was spinning at the highest safe speed. Wasn't sure if it was a reasonable design but the high max speed suggested it might be possible. I'm still coming up short on the math. Mind showing your work? |
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Post by tepidbread on Nov 17, 2018 17:28:12 GMT
Wouldn't the flywheel become unbalanced as soon as the projectile is released? I would assume that this would shake the ship to pieces, break the weapon, or kill the crew.
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Post by treptoplax on Nov 18, 2018 14:52:22 GMT
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