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Rollerons?

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Rex R

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idle questions. toying w/ the idea of rollerons...given that they might spin at ludicris speed, what would hold together, fiberboard soaked in ca? thoughts, comments
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dhbarr

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Fidget spinners. Pre-spin with compressed air, tower launch.
 

markkoelsch

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Rex, how large a rocket and what size motor? What top velocity?


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Rex R

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hmm, hadn't gotten that far in my musing...2 - 2.6" diameter, say 30 -39" long...24mm motor should suffice to lift it, around 200 mph sounds about right for mind sim.
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OverTheTop

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Remember they need to have enough mass to generate enough force from the precession to actuate the control surfaces. Fiberboard might not have enough mass.
 

K'Tesh

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Aluminum? Titanium?
 

snrkl

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Remember they need to have enough mass to generate enough force from the precession to actuate the control surfaces. Fiberboard might not have enough mass.
Are rolleron's active or passive stabilisation? I always figured they were gyroscopic, so they were stabilising as the gyroscopic force resisted direction changes...
 

FredA

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They do indeed work on Gyroscopic action.
Hence you need MASS and SPEED to store any energy in the flywheel.
READ up on flywheel design .... fiberboard is not a common choice for flywheels.....
 

Rex R

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rollerons are used to keep the missile from rolling. I was thinking more along the line having them for apperance rather than for stabilization. if I had used 'air driven whatsit' instead of rolleron...folks might not have known what I was trying to describe :).
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FredA

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Rollerons as I've usually seen them implemented, are indeed "air driven whatsits" in that the usual practice is to use jets of compressed air to spin them up to speed on the pad just prior to launch.

Note - flywheel construction can get tricky fast. Forces add up quick and you don't want to be nearby if one lets go - understand (design) your solution and be very careful testing and deploying.
 
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OverTheTop

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The rollerons are spun up to speed before launch using compressed air I think. During flight any roll will cause precession of the flywheels, which are attached to control surfaces on the rear of the fins. The movement of these control surfaces counter the roll of the missile. With the missile rolling less the targeting system has a lot less to think about and accuracy improves.

Roll introduces a phase shift between the orientation of the control surface and the direction is is trying to control. The faster the roll, the more phase shift. Think something like the elevators on a plane being moved, but the yaw (left/right) direction being controlled by that movement (but in a rotating frame of reference too!). Phase shift can get quite high.
 

Rex R

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the only missiles I saw that used them were air launched at a min speed of around 200kts, they used 'burn strings' to cage the rollerons prior to ignition & launch, a 'P' class motor does tend to remove strings rapidly :). thus endeth my 1st hand knowledge of the aim-9 (or at least what I can say).
Rex
 

OverTheTop

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I might have been getting confused with a HPR rocket version with the compressed air. Thanks for the first-hand knowledge.
 

Rex R

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no problem. according to the wiki there are some versions that are ground launched, and some Navy versions that used a rail based cooling system. Raytheon came up with a elegantly simple solution to a complex problem, way to go Raytheon!
Rex
 

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