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Head Position in a Track

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Considering his experience level, it's pointless for him to worry about de-arching his shoulders to generate non-existant lift when he might be having a hard time going in a straight line.



It's one thing to concentrate on what a novice needs to work on right now. It's quite another to state to tell them that [paraphrase]just get flat because anything else is a waste of time.[/paraphrase]. I teach novices to track and just as you suggest I start something simpler and closer to body positions they can already fly (usually a delta) and we incrementally tweak it a bit at a time towards a better tracking position and the tweaks I suggest are based on observed performance, however, I never mislead them as to where the ultimate goal might be.

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However, I don't believe you are significantly decreasing your vertical descent rate



You can believe what you want. I however, have data. Stable belly to earth for me is around 118-120mph vertical. In a good track, I consistently get down to high 80s to low 90s. On a good day, I'll get it as low as 85mph or so, which I've done on several occasions. That's about 20-25% reduction in descent rate, which is significant.

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However, I don't believe you are significantly decreasing your vertical descent rate



You can believe what you want. I however, have data. Stable belly to earth for me is around 118-120mph vertical. In a good track, I consistently get down to high 80s to low 90s. On a good day, I'll get it as low as 85mph or so, which I've done on several occasions. That's about 20-25% reduction in descent rate, which is significant.



Well, you seem to have answered my last "question" in that post. You have provided data, I have no reason to disbelieve it, and my mind is changed about that. Thanks! :)

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Turn away from the center of the formation if you're on a bigger one, or across the jumprun if you're on a smaller one without losing too much altitude. Start your track by stretching your legs, then de-arch your hips and bring your arms back. Roll your shoulders forward. Tucking your chin in somewhat helps, but you should at all times see where you're going, and if you can't do that with your chin tucked in, don't do it. Things happen around you and you should prioritize looking out.

Most of what decides if you go far or not is not the track position itself, it is what you do in the beginning of the track and what angle you get. If you sink through a lot in the turn and then get a steep angle, you won't get far, you'll just get low.

It's not a bad idea to get someone to coach you in the air and with video. They can tell you what's really going on when you track.

:)
Relax, you can die if you mess up, but it will probably not be by bullet.

I'm a BIG, TOUGH BIGWAY FORMATION SKYDIVER! What are you?

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[reply...............I agree that de-arching and cupping your shoulders, straighten legs, arms close to your side, etc. are ingredients for a good track. However, I don't believe you are significantly decreasing your vertical descent rate.... nor are you "generating" a significant amount of "lift" of the Bernoulli persuasion......



It should be an offense to practice physics or engineering without a license.

Lift is DEFINED as the component of force perpendicular to the free-stream vector. If you are tracking, you must be generating lift.



Points I was trying to make:

1) Tracking does not "generate" a significant amount of lift.



Some people can track at better than a 1:1 glide ratio. That requires a significant amount of lift. For someone with a 200 pound exit weight, the lift needed for 1:1 is over 140 pounds.

Also the vertical descent rate of a GOOD tracker can be below 80mph in a flat track (see previous link), which is a SIGNIFICANT decrease from a nominal 120mph freefall.
...

The only sure way to survive a canopy collision is not to have one.

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[reply...............I agree that de-arching and cupping your shoulders, straighten legs, arms close to your side, etc. are ingredients for a good track. However, I don't believe you are significantly decreasing your vertical descent rate.... nor are you "generating" a significant amount of "lift" of the Bernoulli persuasion......



It should be an offense to practice physics or engineering without a license.

Lift is DEFINED as the component of force perpendicular to the free-stream vector. If you are tracking, you must be generating lift.



Points I was trying to make:

1) Tracking does not "generate" a significant amount of lift.



Some people can track at better than a 1:1 glide ratio. That requires a significant amount of lift. For someone with a 200 pound exit weight, the lift needed for 1:1 is over 140 pounds.

Also the vertical descent rate of a GOOD tracker can be below 80mph in a flat track (see previous link), which is a SIGNIFICANT decrease from a nominal 120mph freefall.



Now that is impressive! That tracking dive (in your link) seems to have resulted in a horizontal speed (over the ground) of 93 mph (based on 77.5 mph vertical rate of descent) in a RW suit! It works out to 1.2:1 glide ratio and he had an actual airspeed of about 121 mph.! I stand corrected!

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Damn. Someone post how to do that. ;)



Go get yourself some booties. :)


Well, body position plays a part too.



OK, where have I gone wrong? I know I'm years out of practice with this stuff but I'm having trouble getting some numbers to work. Using the "observed" data for this tracking jump and arbitrarily using an altitude of approx. 6000 ft as an average I'm getting a lift coefficient of ~0.015 resulting in an observed drag coefficient of ~0.013. Exit wt is 180. My problem comes in when I try to calc the induced drag based on a 0.25 aspect ratio wing (6' x 1.5') with 9 ft^2 area. I tried being generous with the wing size and efficiency (e = 0.7 for rectangular wing shape). Here I get an induced drag coefficient of close to 4. What am I missing? Mental block (happens a lot lately:|)? Mis-appliication?

Edit to say Cd,i should have read 4 x 10^-4 (.0004).

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Also the vertical descent rate of a GOOD tracker can be below 80mph in a flat track (see previous link), which is a SIGNIFICANT decrease from a nominal 120mph freefall.



Holy crap! I always thought I was doing well when I see a nice sub 100 mph sas on my Pro-Track. I guess I have a lot of work to do. [:/]

Edited to add: Heading to DZ with tail between legs to get some tracking in.
Blue Skies, Soft Docks and Happy Landings!
CWR #23
(It's called CRW, add an e if you like, but I ain't calling it CFS. FU FAI!)

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