Sunday, October 5, 2008

Sun Returns to Greenfield, NH on the weekend of October 4 & 5, 2008

Sun was back shining on Yankee Siege this weekend. Temperatures were in the mid 60's, winds were calm and we seemed to have overcome some of our engineering problems of the previous weekend.

We tried out some new items this weekend. First, we tried out a new 10 inch steel trough. We fabbed it by cutting a 10 inch diameter steel pipe into equal halves with a metal-cutting "skill saw". This saw looks and cuts exactly like a wood cutting saw. It leaves a very smooth cut with very little cleanup.

Next we tried to cure our problem of the pumpkin falling out of the pouch. Apparently, what is happening, is that the throwing arm is elastically recoiling when the trigger is released. This is followed by a rebound in the opposite direction, causing a momentary slacking of the sling and a subsequent rolling of the pumpkin out of the sling. We have solved the problem by putting about six inches of slack into the sling and allowing the recoil of the throwing arm to occur before the pumpkin moves down the trough. (Our high speed camera shows the sling actually becoming slack as the throwing arm rebounds).

We threw fourteen pumpkins this weekend with the following results:

Saturday 10/4/08 10,300 pounds counterweight.

Throw One - 1550 feet - slightly low trajectory
Throw Two - 1400 feet - low trajectory
Throw Three - rolled out of sling - didn't put any slack in the sling
Throw Four - 1700 feet - broke 3/16 inch cable stay
Throw Five - 1600 feet
Throw Six - 1500 feet
Throw Seven - 1800 feet - good height
Throw Eight - 1700 feet

Sunday 10/5/08 Added 700 pounds of rail road track to counterweight. Counterweight now 11,000 pounds.

Throw One - 1800 feet - good height, broke cable, bend aluminum extension.
Throw Two - 1900 feet - changed to carbon fiber extension and 1/4 inch cable.
Throw Three - 2000 + feet - good height
Throw Four - 1700 feet - slightly low
Throw Five - 1200 feet - pied into two pieces - cable stay strut slightly bent.
Throw Six - 1750 feet - good height.

Next week we will try adding more weight and trying different pin angles and sling length.

PS All throws were done with orange pumpkins no Lumina pumpkins.

Steve Seigars YS

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