So I got an email a little while a go from Stancil Johnson
He is writing a book on disc golf, from what I hear its pretty comprehensive and I think he been working on it for quite a few yares now.
Anyway, he asked a few questions in regards to a technical paper I wrote a few years back.
I started to answer the questions he had and just started rambling away and,,,,,, well here it is hope its interesting to someone
Ok where to start, first off I too have spoken with Peter a few times ( Geoff and Johnny are 2 of my best disc golf buddies)
Peter gave me quite a bit of insight on how much the under cavity is effecting the flight, which is a big reason some of our newer discs have a concave inside rim under the flight plate, specifically where the rim depth meets the flight plate. I’ve noticed the c urrent discs we use this on ( Apache, Warrior and Element maintain their launch velocities much longer, which equates to longer flights.
Combine this with dimple ( Diablo DT) and surface technology ( Illusion, assassin, apache) on the discs and I guarantee we have some of the best performing discs on the market.
I really don’t mind the questions and observations and know exactly what your talking about when you say I have some contradicting terms. Most of anything I have written or you have read is probably not finished material. There is a whole lot I am leaving out with what I have released to the public so far. Basically I produced some information for the public to create some interest and it hoped to be able to write more someday. At some point I will spend the time and develop much more elaborate technical papers on all that I have learned through disc making and test flying as well as the polymer development.
One thing I haven’t gone into great detail is about resistance to turn and gyroscopic procession.
theres still a whole lot to learn about disc geometry and how things like weight distribution from flight plate to wing effect the flight. by effect the flight I mean maintaining launch rotation, the resistance to turn, stabilizing flight during the glide portion of the flight and the fade on deceleration.
I'm fairly certain discs that are MORE gyroscopic will fade more than discs that are less given the same speed and rotations. the thing is the more gyroscopic a disc is the longer it will stay spinning.
(a question was asked about what I call the shape under the parting line on the wing)
Under camber would be the term for the shape or distance from the nose ( or leading edge) to the bead ( or part that would touch the table if it were laid flat). Disc with more under camber than dome ( shape above the parting line or nose) will be more over stable and have more resistance to turn as well.
And yes the opposite is true. If there is less under camber than dome the discs will be easier to turn, but discs will a lot more mass at the rim will fade sooner and harder than those with less ( more centrifugal designs like mid-ranges).
I suspect you will see very few long range drivers ever produced again with large concaved under cambers like a whippet or blaze.
Small amounts of concave here or small beads do a much better job of giving a disc resistance to turn ( HSS high speed stabliility). IMO
You should see our latest disc,, the APache
It has just about equal amounts of dome VS under camber, but a small bead to give it the resistance to turn it needs for high velocity high rotation releases. We also have an unpolished under camber ( with grooves from the cutters) as opposed to a polish surface here. This technology does and incredible job of reducing over all drag on the discs.
We also have the larger radius where the rim depth meets the flight plate to further reduce the drag on the disc as opposed to a tight shoulder that does not allow the air flow out of the cavity as easy.
some could say this trapped air gives the disc more lift but I'd rather see a long range driver maintain its speed as opposed to slowing down because of the added drag.
I could go on and on about how these variables can easily change based on mung or nose trajectory, which can allow more or less air to reach the under camber and subsequently the under cavity.
I’ll give you an example: top pros can throw putters at high trajectories ( 40 plus feet in the air) but they can still be somewhat flat,,,even nose down and fly far,, while some lesser skilled players will put an air bounce or nose up release, even when trying to throw a driver 6 feet of the ground. this shot goes nose up and stalls without getting much distance no matter how hard its thrown.
So much is going on with the flight of a discs its dumbfounding.
Let me explain how many variables there can be for just the throw, never mind the disc shape and/or aerodynamics of the surface.
Here are the factors:
Launch speeds = 0-75 mph
Off axis rotation = smooth as silk or wobbling like a tire missing all but one lug nut.
Rotation = from just about Zero to 2500 ( I would love to test this to see how fast a disc can actually be spun upon release.)
Left and right angle of release ( Hyzer) = with 90 degrees being a flat release a disc can be released from 0 to 90 or from 91- 180 ( EVEN MORE IF YOU COUNT THUMBERS AND OVERHANDS)
Mung angle of release = from a dead flat to really nose down or really nose up. ( not sure of the degrees maybe plus or minus 20 degrees is possible depending on trajectory.)
Trajectory = worm buring or straight up in the air and everything in between. typically a disc is thrown between 3 and 30 feet off the ground.
Wind = up wind, down wind, cross winds basicall fro 12 olclock all the way around back to 12,,, 0 mph or 60 mph,,, all effect a discs flight.
Temperature = freezing cold or burning hot.
humidity and barometric pressure = ok maybe I'm reaching here, but I bet its a variable.
Elevation = 200 feet below sea level ( Badwater Basin) or 10,000 feet at sno-bowll in flaggstaff
Combining all these variable will produce just about an infinite amount of combinations of them, basically no 2 discs can be thrown the same.
Lets assume the following throws are with stable flying discs like a Sabre or Tee bird.
Player 1:
55 MPH with lots of off axis rotation and only 800 rotations per minute. If this guy does not have a nose up hyxer release the discs will turn straight to the right.
Player 2:
45 mph release speed that’s smooth as silk and 1200 rpms will produce a flat flying shot when released with a touch of hyzer and slightly nose up.
Player 3:
45 mph release speed that’s smooth as silk but with 1800 rpms will need more hyzer or more nose up or it will turn over and go to the right.
Player 4:
45 mph release with only 800 rotations per second and a smooth release will need to turn the disc over right out of the hand and it wil probably still hyzer out because of lack of spin.
ok I need some sleep!
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