Distance covered vs. Vertical speed

[Tonto 1]

I need some input here.

It seems to me, out here in Africa with few people to learn from, that the dives I cover the most distance on have relatively high vertical speeds.

Is there a "Fastest airspeed" vs a "Maximum time" mode of flight? Seems when I'm covering the most distance on my Classic, I'm doing around 70mph.

Is this about right?

t

It's the year of the Pig.

[nicknitro71 0]

Tonto,

I'm still a rookie on my S3 so take it with a grain of salt but thus far that is my impression. If I go for distance, i.e. legs straigth, slight de-arch, slightly bent elbows, shoulders rotated, hands on the winglets, my speed is in the mid sixties. Again on a S3 and I'm about 170 out the door.

If I try to float more I have to cup my shoulders even more and slightly bend my knees; by doing so the speed goes down to the lower fourties but it seems I cover less ground. I'm planning to jump with my GPS, a Rhino 120 but I don't know how good it is for such a task.

Memento Audere Semper

903

[Tonto 1]

Thanks for the reply.

I'm 187 out the door, and my distance body position sounds very similar to yours.

What I don't understand is how bending your knees slightly (and so decreasing surface area) gets you to float more... Ahh, the little mystries of flight...

t

It's the year of the Pig.

[TomAiello 26]

I think you're right. I'm generally of the opinion that forward speed generates lift, which means that a faster flight (in both forward and downward directions) will achieve better glide ratio.

Robibird posted a long discussion about this, either here or over on the BLiNC wingsuit forum a while back. You might have a look and see if you can find it.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[nicknitro71 0]

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What I don't understand is how bending your knees slightly (and so decreasing surface area) gets you to float more... Ahh, the little mystries of flight...

I don't think that slightly bending the knees reduces the surface area. Completely kicking your butt with your feet will do so but a slight bent is almost equal to pulling the stick back hence elevating the elevator on the horizontal stabilizer. That's how I picture it anyhow. Same thing when you cup your shoulders making your wings more gulled hence increasing slow flight charateristics, I think.

Memento Audere Semper

903

[The111 1]

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What I don't understand is how bending your knees slightly (and so decreasing surface area) gets you to float more... Ahh, the little mystries of flight...

Perhaps since it is decreasing surface area behing your CG, it allows your pitch angle to become less "head low" and that pitching adds more to your surface area projection than was taken away by the leg bend. Just a wild guess...

www.WingsuitPhotos.com

[The111 1]

Check out this link about glider performance... I think Quade posted it before in another forum.

www.WingsuitPhotos.com

[LouDiamond 1]

There have been a few discussions on this but the short answer is faster horizontally you are flying, the more lift you can generate hence longer time. Horizontal Speed and time aloft go hand in hand,they are not seperate from one another. Straight legs are ALWAYS better than bent legs when attempting a max flight. Robibirds comments on it are HERE

"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

[nicknitro71 0]

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There have been a few discussions on this but the short answer is faster horizontally you are flying, the more lift you can generate

sort of

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hence longer time

I don't agree. The longer time equals the minimum sink rate that does not equal better glide ratio.

Memento Audere Semper

903

[outrager 6]

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hence longer time

I don't agree. The longer time equals the minimum sink rate that does not equal better glide ratio.

This is true. However for many wings (including our wingsuits) these two dots on a polar will not be too far apart. To complicate things a bit, we don't have a single polar here because most people would change the shape of their wing(suit) trying to achive either a minimum sink or a max glide.

What that means in practical terms: your mileage will vary (so it doesn't mean much eh? ;-) Most of the time i go for max glide i seem to fly at/near my minimum sink rate. Others with a similar wing loading achieve their highest glide at significantly higher vertical/horizontal speeds. Since the laws of aerodynamics don't bend, we do by shaping our bodies (the wing) differently according to personal preferences. For example bending the knees, while bad in theory, gave me the best possible glide flying Classic. Even in Skyflyer 3 i push my knees down and keep a slight bend to balance the suit. Other people keep them straight and get good results. A stronger stomach would allow one to dearch more while keeping straight legs, but extra muscle bulk and mass can bring their own disadvantages. IMHO flying a suit is an art of balance, and everybody finds it at a slightly different point of the curve.

bsbd!

Yuri.

[ManBird 0]

You can't achieve your fastest (potential) forward speed and slowest (potential) fall rate at the same time. When it comes to distance, you look for a compromise to achieve the highest glide ratio. You also have to take wind into consideration, but one thing at a time.

Generally (aka, with an average build), achieving your fastest forward speed (and therefore overall velocity) will involve falling faster by about 20% of your slowest sustained fall rate. Your slowest sustained fall rate will usually peel off about 20% of your fastest forward speed. Your best glide ratio will usually warrant a fall rate that is about 10% faster than your slowest fall rate, and a forward speed that is 10% slower than your fastest. This is all relative, and only translates to to true glide ratio in no wind.

If you have a head wind, you will get a better glide ratio as you increase your forward beyond that of your best no-wind glide ratio (which results in a faster fall rate). If you have a forward speed of 85MPH and a fall rate of 44MPH in your "best glide" body position, but are flying into a 50MPH headwind, your actual glide ratio will only be 0.8:1, not 1.93:1. If you increase your forward speed to 102MPH, which may result in a 53MPH fall rate, your glide goes from 0.8:1 to 0.98:1, even though it would be a slightly lower glide ratio in no wind. This means you'll cover an extra 2 inches for each foot you drop... over 800' of extra distance over 5,000' of freefall (though it does shave off some freefall time). When you open 800 feet ahead of your buddy at the same altitude, you'll really notice the difference.

The opposite is true for a tailwind. So your best glide is still 1.93:1, going 85MPH forwards and 44MPH down. If you have a 50MPH tailwind, this results in a 3.07:1 glide ratio. Now if you can "float" down to 40 MPH, which may reduce your forward speed to 78 MPH, you now have a 3.2:1 glide ratio, even though you've reduced your no-wind glide. You actually gain 1.56" in distance per foot dropped (plus you get a longer freefall), resulting in an extra 650' traveled.

Wind only affects your forward speed, not your fall rate. It can drastically alter your glide ratio, and should not be ignored when going for distance.

"¯"`-._.-¯) ManBird (¯-._.-´"¯"

Click

[ManBird 0]

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Seems when I'm covering the most distance on my Classic, I'm doing around 70mph.

Assuming your build is average (in terms of the length of your limbs) and at your body weight, 70 seems high for even going fast forwards in a Classic. Best glide on a Classic tends to be 1.4:1. Exceptionally tall and skinny guys get like 1.6:1. If your forward speed is up to 70 or 80, then your fall rate should be 50 - 60.

"¯"`-._.-¯) ManBird (¯-._.-´"¯"

Click

[LouDiamond 1]

Again, I think individual body shape plays some role and unquestionably, the wingsuit pilots abilities but the bottom line is you need speed. Another descriptor HERE

"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

[pbla4024 0]

And it's something like 2.5:1 for S3. And for GTI?

Fido

[nicknitro71 0]

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And it's something like 2.5:1 for S3

Probably only Jari, Robi, or few others get 2.5!

Memento Audere Semper

903

[Tonto 1]

I meant 70 vertical. I wasn't wearing my GPS, so I have no idea of ground speed or uppers.

t

It's the year of the Pig.

[pbla4024 0]

Actually, I calculated it from Yuri's Eiger flight.

Fido

[TomAiello 26]

Yuri did those flights with Robert. He told me that Robert and he had about the same glide angle, but Robert was moving faster in both the forward and downward directions.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[ManBird 0]

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And it's something like 2.5:1 for S3

Probably only Jari, Robi, or few others get 2.5!

Naw, quite a few get that, actually. GPSing on a no-wind day dispels a lot about what forward speeds we once thought that we had.

"¯"`-._.-¯) ManBird (¯-._.-´"¯"

Click

[flyinfishman 0]

Up to 1.71 G/R in my Gti.
I'm going to keep trying to improve, but is there anymore room for improvement?

Winds aloft were L+V, forward speed 83 MPH average. (fall rate at 48 avg)
3.6 miles.
I used GPS and Steve's G/R calculator.

http://www.deepart.org/code/counttracula/

I've started to learn to use the forward speed correctly and it's increased my G/R quite a bit.

Sucking in the gut, feeling the low pressure/burble on the stomach, sweeping the hands back to slice through the air, it all helps.
Forward speed is definitely your friend!

Anyone know what G/R the PF is expected to get?
(compared to say, the S3?)
JIM

[ManBird 0]

Sweet! It's time for the S3. That's about the best anyone is going to get in a GTi. No -- there is no room for improvement. Hurry up and get your next suit! Nice job!

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Anyone know what G/R the PF is expected to get?

Reportedly as high as 3:1. Watching videos of some of Robi's flights, I believe it.

"¯"`-._.-¯) ManBird (¯-._.-´"¯"

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[KrisFlyZ 0]

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Reportedly as high as 3:1. Watching videos of some of Robi's flights, I believe it.

Where did you find these videos??

Kris.

[ManBird 0]

skydivingmovies.com has some. Check out yotbm.wmv and Robi's low pull video. Watch for the white prototype. It's not the PF suit as we'll see it this fall, but it's freaking amazing nonetheless (the final one will probably be better).

"¯"`-._.-¯) ManBird (¯-._.-´"¯"

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