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This is my prototype fiffer trebuchet modeled after the First in Fright machine that can
be found here on youtube they took second place at the pumpkin chuck last year with
a throw of 1920 feet I liked their design so I built a small one just for some testing
some basics of the design up front this is where the counterweight would be attached
as the counterweight falls it falls in a nearly vertical track guided by this long beam which
pivots back here as the counterweight falls it causes these two linkages to scissors apart
making this pin here move down and forward as that pin moves down and forward it pulls
on this web strap which transfers the power up to the arm through these cams the First
in Fright machine uses a linkage instead of web strap and cams I thought this was easier
to construct I didn't have to have a linkage the correct length maybe a little more light
weight in the future larger designs maybe i'll have trouble finding materials strong
enough to pull the arm around but for now I think i'm good one disadvantage of using
a web strap and a cam is now I have to catch the arm which is what these ropes are for
up front here compared to an onager this is a pretty easy catch there's no tension from
the wrappings the counterweight is off and with a properly tuned throw the arm should
be moving fairly slow at the end of the launch anyway i'm hoping in the future that I can
modify these cams instead of being semi-circles to be more oblong to provide more efficiency
and a faster throw some items I like about the fiffer design first as I said before the
counterweight falls nearly vertically which is the goal of all FAT floating arm trebuchets
and F2K's ... like I said this falls nearly vertically has a little bit of arch but is
pretty minimal I like that instead of having the friction of a linear track the only friction
for the counterweight is from this pivot back here which is much less than a vertical track
also the linkages here provide a much great leverage when the weight is up and moving
slow ... for your arm creates a lot of tension here as the counterweight falls it picks up
speed and your arm is picking up speed it's losing leverage but gaining velocity causing
your arm to move faster I like that another thing I like is the counterweight can be caught
when this falls it lands on the ground or without my counterweights on it lands on these
two beams down here theoretically you could catch a floating arm counterweight or an F2K
but your arm would at the vertical position when it is caught which is not ideal here
I can let the arm get just past the vertical position when my weight is caught reduces
the jolt on my machine but I still get the full power of the throw this design also seemed
fairly stable this guides it well I don't have to worry about wheels staying on tracks
I don't have to worry about swing through that you get with a suspended counterweight
trebuchet up front here is my trigger I will post a link for the design of this trigger
on the side I have added a safety to it you can see through that hole that is connected
to the inner piece keeps it from accidentally firing talking about accidental firings one
thing I like about the web strap that you don't get with the linkages I can unhook the
arm from the counterweight so that the sling can be set and if there is an accidental triggering
you don't have to worry about getting caught in the sling I also like that it is almost
a remote drop the counterweight falls over here and the arm is over here so they can
be separate these arm the same height this arm could have been higher the counterweight
could have been higher I also can have my arm in the vertical position here which gives
it a fill 180 degrees swing a lot of time to put power into your projectile I will now
give the machine a launch so you can see its general motion as you can see the arm comes around fairly
easily even without any counterweight I had about 180 pounds on this machine at the Shiocton
Cabbage Chuck this past weekend and we were throwing pears over 300 feet I hope you enjoyed
this video and good luck chuckin