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Basic Rollergun Energy Storage Diagrams

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popgun pete

popgun pete

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Jul 30, 2008
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Another rollergun type is the "Fusion" which is a hybrid of the other rollergun types and is distinguished by having a short set of bands which remain on the gun’s top deck and which are connected to the end of the drive cables that wrap the muzzle rollers. That means the bands do not travel around the muzzle rollers at any time, most of the propulsion being derived from the bands on the bottom deck. If the bands top and bottom are the same rubber type and size then the upper set don’t have to be stretch limited, but if the lower bands are thicker or in multiple sets with a bifurcated connection to the drive cable then the top bands need an inner cord to stop them being over stretched. Being stretch limited they add nothing to cocked gun cable tension until the spear is released at which time the top band set can start to contract. The diagram below compares a standard rollergun (if there is such a thing) to the simplest form of a Fusion rollergun.
Fusion rollergun
 
popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
4,435
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Because the same band rubber connected in series with a load applied to it always undergoes the same proportion of stretch in the various segments I had to slightly modify the diagram accordingly to work out the energy storage diagrams. This is the result and you can see the Fusion rollergun stores less energy for the shot all things being equal than the standard rollergun. Ergonomically it may be easier to load just because you have something more substantial to grab onto i.e. those short top bands, but giving away wishbone travel has its consequences. Using piggy back bands to pile on more rubber can change the situation and that is usually the purpose of composite band guns that link more bands onto a given run of cable by splitting the rear ends to run to separate anchors on the rear underside of the gun. One advantage of the Fusion rollergun is the bands don't get bent around the rollers where some energy must be lost during the shot.
Fusion rollergun energy comparison
 
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