Forums: Skydiving Disciplines: Swooping and Canopy Control:

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jephprospect  (Student)

Jul 12, 2010, 11:24 AM
Post #1 of 48 (2181 views)
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Is there a chart anywhere for how many mph you will go on a canapy based on your wingload? I searched the forums as well as google and didn't find much.

jephprospect  (Student)

Jul 12, 2010, 12:18 PM
Post #3 of 48 (2155 views)
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I understand and agree. But is there a ruff estimate anywhere?

Jul 12, 2010, 1:06 PM
Post #4 of 48 (2125 views)
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I understand and agree. But is there a ruff estimate anywhere?
.

Not that I've seen.

The problem is that someone under a 170 loaded 1.5:1 will have a different speed than someone under a 120 loaded at 1.5:1 due to the drag of the longer lines and larger canopy (even if its the exact same model of canopy). Then you can take into account the jumper's jump suit material and design, and a lot of other "little" factors that change the neutral flying speed of the canopy.

The next question is why do you want to know? Is this a beer light argument you got into with a friend or is this just something you're trying to figure out? There is absolutely nothing wrong with asking the question, but there may be a different question to be asked to answer you underlying curiosity.

jephprospect  (Student)

Jul 12, 2010, 1:20 PM
Post #5 of 48 (2114 views)
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 Re: [AggieDave] wingload speed [In reply to] Can't Post
Pure curiosity really. I'm curious to know how fast I am going. I'm flying a safire 2 169 at a 1.1 W/L. Let's say i'm not wearing a jump suit, no winds, and I'm doing a standard approach. Around how fast am I going? It feels like maybe 15 mph at the most.

Jul 12, 2010, 1:26 PM
Post #6 of 48 (2111 views)
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 Re: [jephprospect] wingload speed [In reply to] Can't Post
Pure curiosity really. I'm curious to know how fast I am going. I'm flying a safire 2 169 at a 1.1 W/L. Let's say i'm not wearing a jump suit, no winds, and I'm doing a standard approach. Around how fast am I going? It feels like maybe 15 mph at the most.

Generally speaking you're probably in the 15-20mph range as an educated guess. There are those crazy wingsuit types who have those nice GPS setups that would let you graph out your ground speed. Depending on where you jump, you may be able to talk one of those folks into borrowing their setup!

I've known others to take up a hand held anemometer to get their airspeed. If you do that, please do this by yourself, on a solo hop-n-pop, with no other traffic and do it well above your pattern altitude! Obviously its not the most scientific approach, but hey, you're just wanting a rough number for fun, right?

DrewEckhardt  (D 28461)

Jul 12, 2010, 1:39 PM
Post #7 of 48 (2103 views)
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 Re: [jephprospect] wingload speed [In reply to] Can't Post
Is there a chart anywhere for how many mph you will go on a canapy based on your wingload? I searched the forums as well as google and didn't find much.

EIFF claims 22 mph full-flight forward speed for their accuracy canopy loaded at .65 pounds/square feet. Having jumped F111 seven cells around that wing loading in 20 MPH winds without going backwards that seems right.

Speed increases with the square root of wing loading. Double wing loading and you get a 40% increase in speed.

This ignores what happens following speed inducing maneuvers and that perception isn't linear.

(This post was edited by DrewEckhardt on Jul 12, 2010, 5:38 PM)

mchamp  (D 32129)

Jul 12, 2010, 9:14 PM
Post #8 of 48 (2040 views)
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 Re: [DrewEckhardt] wingload speed [In reply to] Can't Post
Referring to speed under canopy. Why is it that if you are under say for example a velo 75 loaded at 2.5 doing a 270° you have a higher entry speed but with less distance compared to a velo 96 loaded at 2.3? Or am I completely getting this wrong? How would it compare to the same wingloading under same conditions?

Does speed not equate to a further swoop? Can't quite grasp the physics lol. I'm assuming it has something to do with momentum
btw just asking out of pure curiosity.

skydiverkeith

Jul 13, 2010, 6:36 AM
Post #10 of 48 (1972 views)
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 Re: [AggieDave] wingload speed [In reply to] Can't Post
Pure curiosity really. I'm curious to know how fast I am going. I'm flying a safire 2 169 at a 1.1 W/L. Let's say i'm not wearing a jump suit, no winds, and I'm doing a standard approach. Around how fast am I going? It feels like maybe 15 mph at the most.

Generally speaking you're probably in the 15-20mph range as an educated guess. There are those crazy wingsuit types who have those nice GPS setups that would let you graph out your ground speed. Depending on where you jump, you may be able to talk one of those folks into borrowing their setup!

I've known others to take up a hand held anemometer to get their airspeed. If you do that, please do this by yourself, on a solo hop-n-pop, with no other traffic and do it well above your pattern altitude! Obviously its not the most scientific approach, but hey, you're just wanting a rough number for fun, right?

You don't need a nice setup. I just pulled my garmin nuuvi gps out of my truck. No calculations to make. After the canopy opens, just pull it out and look at your speed. Turn and you get downwind, upwind, and crosswind which you can use to easily figure out your speed in no wind (or just jump in no wind)

Mike.d  (C 107643)

Jul 13, 2010, 8:09 AM
Post #12 of 48 (1934 views)
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 Re: [mchamp] wingload speed [In reply to] Can't Post
Referring to speed under canopy. Why is it that if you are under say for example a velo 75 loaded at 2.5 doing a 270° you have a higher entry speed but with less distance compared to a velo 96 loaded at 2.3?

Well firstly to some of the early points people where making, Flying speed of a canopy has nothing to do with wind speed, its all relative.

If my canopy is flying at 30 knts into a head wind of 10 knts my canopy speed is still the same as flying at 10 knts down wind, (30knts) the only thing that changes is our ground speed.

Moving onto swoop distance on the velo 96 and 75 this is due to glide ratio, and the polar curve that the canopy has. E.g the rate it sinks at to the hight lost (what its optimum glide is) this is affected by the wind speed moving the polar curve to the left or right depending on wind strength and direction in relation to the wing.

I believe i have explained that correctly but your best bet is to look it up in the book canopy and its pilot, as i am taking my flight experiences mainly for gliding

Jul 13, 2010, 4:22 PM
Post #13 of 48 (1859 views)
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 Re: [skydiverkeith] wingload speed [In reply to] Can't Post
Quote:
You don't need a nice setup. I just pulled my garmin nuuvi gps out of my truck. No calculations to make. After the canopy opens, just pull it out and look at your speed. Turn and you get downwind, upwind, and crosswind which you can use to easily figure out your speed in no wind (or just jump in no wind)

That's neat, hadn't heard of anyone trying it with that setup before.

kameraflyr  (D 20455)

Jul 13, 2010, 6:54 PM
Post #14 of 48 (1834 views)
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 Re: [Mike.d] wingload speed [In reply to] Can't Post
Mike,
Refering to the speed/distance question, the glide ratio of two identically designed canpoies under the same wingload has much less to do with glide and much more to do with parasitic drag and available lift. Parasitic drag (increases with canopy size and certain shapes)and the canopies available lift or "stall point" is where the canopy bleeds off lift as speed decreases (increases with smaller sized canopies.
Translated:
the 96 given the same entry speed and wingload would "likely" go farther given that it's size advantage enables it to maintain lift at lower speeds.
This of course assumes that the drag of the increased size does not overcome this advantage
(ie. head wind on landing which increases this exponetially)

Mike.d  (C 107643)

Jul 14, 2010, 12:13 PM
Post #15 of 48 (1750 views)
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Kameraflyr
Do you know what a polar curve is?
Have a look at this,
http://www.jdburch.com/polar.htm
The polar curve changes as we also add weight, all explained on there.
Plus you could plot several canopies on one graph and see what happens to them at different speed, etc etc

this is also a good read
http://www.auf.asn.au/...es/aircraft.html#vbg

An last but least

http://en.wikipedia.org/wiki/Parasitic_drag

ach of these forms of drag changes in proportion to the others based on speed. The combined overall drag curve therefore shows a minimum at some airspeed - an aircraft flying at this speed will be at or close to its optimal efficiency. Pilots will use this speed to maximize endurance (minimum fuel consumption). However, to maximize gliding range in the event of an engine failure, the aircraft's speed would have to be at the point of minimum power, which occurs at lower speeds than minimum drag.

Key sections here are maximum endurance (e.g. fuel) and maximizing the gliding range!

(This post was edited by Mike.d on Jul 14, 2010, 12:30 PM)

castrodavidd  (C 33299)

Jul 14, 2010, 12:23 PM
Post #16 of 48 (1746 views)
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Quote:
Do you know what a polar curve is?

I don't and have studied and taught aerodynamics, please explain.

Mike.d  (C 107643)

Jul 14, 2010, 12:38 PM
Post #17 of 48 (1738 views)
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castrodavidd  (C 33299)

Jul 14, 2010, 1:29 PM
Post #18 of 48 (1724 views)
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 Re: [Mike.d] wingload speed [In reply to] Can't Post
OK, I can see how that would be usefull to a glider pilot but I don't think it correlates very well to the question. If we were flying paragliders with high lift to weight ratio, we could worry about rising and decending air.
Because induced drag decreases with airspeed and parasite drag increases with airspeed any airfoil will perform it's best at L/D max "best lift over drag airspeed. That being said wind will have an effect on glide ratio in non still air. As we all know we move farther across the ground when flying with the wind.
When talking about the length of distance across the ground we cover in a flare we are talking about energy and the ablity of our canopy to use that energy. The 96 he is refering to will have a slower approach speed an a higher glide ratio in the flare due to the increased drag and the decreased load factor and the larger surface to transfer the energy of airspeed and altitude into lift. The same reason while the wings on your glider are so damn long. His 76 will fly faster but will not glide as far because it has a higer terminal velocity "less drag" but doesn't have the ability, becuase of its size, to transfer as much energy into lift. The higher performance we make a wing the higher L/D max will be. ie. Your glider might be 35 knots while the jet I fly is 250. As far as the ability to transfer energy a helicopter makes a perfect example. We could make helicopter bades half the size that they are and they would perform better in flight, however durring autorotation becuase the lower enertia they would not be able to transfer enough energy to lift to alow a safe touchdown.
I hope this answers some questions.

kallend  (D 23151)

Jul 14, 2010, 3:21 PM
Post #19 of 48 (1704 views)
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 Re: [Mike.d] wingload speed [In reply to] Can't Post
Kameraflyr
Do you know what a polar curve is?
Have a look at this,
http://www.jdburch.com/polar.htm
The polar curve changes as we also add weight, all explained on there.
Plus you could plot several canopies on one graph and see what happens to them at different speed, etc etc

this is also a good read
http://www.auf.asn.au/...es/aircraft.html#vbg

An last but least

http://en.wikipedia.org/wiki/Parasitic_drag

ach of these forms of drag changes in proportion to the others based on speed. The combined overall drag curve therefore shows a minimum at some airspeed - an aircraft flying at this speed will be at or close to its optimal efficiency. Pilots will use this speed to maximize endurance (minimum fuel consumption). However, to maximize gliding range in the event of an engine failure, the aircraft's speed would have to be at the point of minimum power, which occurs at lower speeds than minimum drag.

Key sections here are maximum endurance (e.g. fuel) and maximizing the gliding range!

Another variable is the canopy trim. The full flight trim speed is generally faster than the best L/D, and the exact position varies according to the canopy design (as well as the age of the lines).

kallend  (D 23151)

Jul 14, 2010, 3:23 PM
Post #20 of 48 (1701 views)
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OK, I can see how that would be usefull to a glider pilot

Not just useful - it's required as part of the written test for the glider rating.

I fail to see why you think it doesn't apply to the question.

castrodavidd  (C 33299)

Jul 14, 2010, 5:01 PM
Post #21 of 48 (1682 views)
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Quote:
Not just useful - it's required as part of the written test for the glider rating.

I fail to see why you think it doesn't apply to the question.

OK I will conceed, If your flying up high back from a long spot, dealing with shifting winds, rising and falling air, and hand an aispeed indicator this would be great. As a pilot are you thinking about this in your landing flare? No. Your goal on landing is to bleed off airspeed for lift to touch down at the slowest possible speed. Its the same for canopy flight.

kallend  (D 23151)

Jul 14, 2010, 8:50 PM
Post #22 of 48 (1661 views)
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Quote:
Not just useful - it's required as part of the written test for the glider rating.

I fail to see why you think it doesn't apply to the question.

OK I will conceed, If your flying up high back from a long spot, dealing with shifting winds, rising and falling air, and hand an aispeed indicator this would be great. As a pilot are you thinking about this in your landing flare? No. Your goal on landing is to bleed off airspeed for lift to touch down at the slowest possible speed. Its the same for canopy flight.

Did you bother to read the OP?

At what level did you teach aerodynamics? I have yet to see a text book on airplane aerodynamics that didn't include polar curves.

(This post was edited by kallend on Jul 14, 2010, 8:53 PM)

castrodavidd  (C 33299)

Jul 14, 2010, 10:16 PM
Post #23 of 48 (1648 views)
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Quote:
At what level did you teach aerodynamics? I have yet to see a text book on airplane aerodynamics that didn't include polar curves.

My experance in aviation is Flying for 12 years professional since 2003. I flew CH-47 in the Army and currently fly corporate jet for a living. I have been a flight instructor since 2005 on both airplanes and helicopters. I hold a Comercial license with an instrument rating for Airplanes multi and single engine land, and helicopters. CFI both airplanes and helicopters and three type ratings. DA-20, IA-Jet, and CH-47. Whats yours.
Also I can't find a polar curve in the "pilots handbook of Aeronautical Knowledge" witch is considered the primary source the FAA request Instructors teach from. Maybee I just missed it.

(This post was edited by castrodavidd on Jul 14, 2010, 10:17 PM)

Mike.d  (C 107643)

Jul 15, 2010, 3:59 AM
Post #24 of 48 (1614 views)
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oh shall we start talking about rears as well, changing our angle of attack. To be honest get a neptune 3 an plug it into a PC it will spert out all the info of decent rates etc etc, and you can draw pie charts and graphs etc etc till they come out your ears.

Kallend
I have to say im very shocked with your experiance you have not heard of a polar curve though this is very basic stuff when coming to flying.

Jul 15, 2010, 6:44 AM
Post #25 of 48 (1594 views)
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Doesn't pulling on rears change your angle of incidence, not angle of attack?

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