Too late...I've unstuck! :)
For weeks I thought the same, it didn't seem to work.
I made ideas one after another, for parts of the
crossbow, but they didn't fit together (too big, too long,
too heavy, one part makes the operation of the other
one impossible...I have details, but they are...
Stuck with that. (trigger)
I don't give up!
Basically, it's not so hard to make one, but I want such one which stops
the "limbs", not the string. The reason is to launch light projectiles
at higher speeds. In that case, the string load would only consist of the inertia of
the accelerating...
M-Cameron, your every line is either gloomy, not true, or contains pseudo-science.
Please don't take it as an offense, because it disturbs much more people
who take science seriously.
The good thing is, anybody can alter the fork width while
keeping energy unchanged.
X times less spacing, X times more folds of rubber
band, still no play, smaller draw length, bigger
draw force, same energy.
All right. Your math is not exactly OK, because you fail
to show how exactly that force of yours does work
on (actually non-existing) displacements. No displacement
sideway: no work by sideway force. You just calculate
the side component of the band pull force.
:banghead:
...Joerg's experience,
he and others might get better efficiency accompanied
by a narrower fork. I say it's unclear if there's an another
factor* interfering with efficiency. I doubt your reasoning,
that exactly and only the width is the reason of the efficiency change.
*For example...
Never mind, Joerg, do what you think is right,
given all the circumstances, you must be right
about fork width, but what M-Cameron says...
that's medieval.
P.S. - I'm glad to hear you have a physicist brother.
One physicist is enough, huh?:)
M-Cameron:
Here's the proof.
l= the total loose lenght of the rubber band
K=spring constant of the rubber band
F (not F(s))= maximum rubber load (one band)
No link, no book,
no "my experience".
I think the alleged change in efficiency in
practice is due to that many things
are...
I r o n y.
I guess all the engineers around the world should be
fired, they're useless, because they calculate before build.
Cars, airplanes, guns are just grown on farms,
unless built from LEGO by trial-and-error.
Picatinny all over the cover?
:D
"Groovy, baby!" (Austin Powers)
OK, I googled "excalibur trigger pull".
The trigger is a little stiff (3-3.5lbs), and there's a big pull
before the let-off.
...rubber is 8 times more
than that of spring steel.
(No, I'm not stating that rubber is stronger.)
NERD WARNING
Formula: (Spec. Energy)=0.5*(sigma^2)/Y/Rho
Y: Young's modulus, "rigidity"
sigma: Elasticity limit (almost like "breaking stress")
Rho: density
So, rubber is weak...
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