Technical question at swooping

[grega 0]

Can anyone explain me how building speed at swooping works and why.
I know that if you pull both front risers angle of incidence gets steeper - canopies heading is steeper, that why it goes faster.
If you pull only one riser (left or right) only one side of the canopy gets steeper-dives faster and you make a turn. during a turn centrifugal turn is present, because of which, canopy is loaded heavier and is going faster through air and has better lift.
My question is:
Why does the canopy gain speed?

-Is it because of centrifugal force that loads your canopy much heavier than it's already loaded. in that case swooper would probably got more speed if he made sharp turn where centrifugal force is big, and throws canopy pilot even up a little, well at least it looks that way, and while the centrifugal force is big, planes the canopy out.

-or is it because in a turn you can keep canopies angle of incidence very steep. in that case it is probably better to start making turns up high and make several spirals, or at least that many to achieve maximum speed you can, and then plane out your canopy.

-or is it something in between?

I know that this centrifugal force and turning is all mixed together (to have centrifugal force, you have to turn, and vice versa) but which is more important to gain more speed canopies angle of incidence of centrifugal force?

any explanation would be appreciated, 10x

"George just lucky i guess!"

[bobsoutar 0]

Speed for swooping is generated by gravity, the earths pull. The steeper your angle of attack, the faster you will go down - this speed is then converted into speed across the ground when you plane out of the dive.

[Ron 10]

The canopy gains speed due to the angle of attack of the wing. You have to trade potential energy (Altitude) for Kinetic (Speed). Gliders work on the same concept. To speed up they have to dive. The only way to do this with a canopy is to pull both front risers....But this will only increase the angle of attack a little.

When you turn, you place the canopy into a dive. This dive will continue until:

A. The jumper comes out from under the canopy due to the difference between the drag on the canopy and the jumper.
Durring the dive the canopy will continue to speed up.
You can increase the drag on the canopy by pulling the toggles, and this will pull you out faster.

B. You slam into the ground and die.

Have fun!!

Ron

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[Sonic 0]

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But this will only increase the angle of attack a little

does it actually alter the angle of attack of the canopy, or just the angle of incidence?

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It's like something out of that twilighty show about that zone

[quade 4]

In addition to what Ron has said, there are a few other factors as well, but chiefly among them is the concept of drag. A high angle of attack creates more drag than a low angle of attack. As the speed of the canopy increases however, parasite drag will increase as well until it reaches a terminal amount. This is why, all other things being equal, a smaller canopy can go faster than a larger canopy.

quade -
The World's Most Boring Skydiver

[quade 4]

I'm only saying this for clairification and not to correct any one person in particular, however, as referenced in some skydiving texts used by some very well known canopy schools the terms are being used incorrectly and I believe this is where the confusion is coming from.

Angle of Attack (AoA) and Angle of Incidence sometimes get confused when people talk about canopies.

Angle of Incidence is the mechanical angle created by the length of the lines relative to the canopy.

AoA is the angle between the mean chord line of the canopy and the relative wind.

quade -
The World's Most Boring Skydiver

[AggieDave 6]

That is also why the forward speed of a 170 loaded at 1.4 will be a bit slower then a 100 loaded at 1.4.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[franck102 0]

Quote

Quote

But this will only increase the angle of attack a little

does it actually alter the angle of attack of the canopy, or just the angle of incidence?

Both - pulling on the risers directly modifies the angle of incidence, which is just defined by the geometry of the pilot/line/canopy system.
Once this happens the angle of attack (the angle at which the apparent wind hits the canopy) must decrease to return to stable (faster) flight.

Franck

[Samurai136 0]

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My question is:
Why does the canopy gain speed?

The canopy gains speed because your mass is the thrust that drives the canopy. Let's say the full flight angle of attack (wing) is 15 degrees (15*) below the horizontal. It is similar to riding a sled down a 15* slope. If you increase the angle of attack it is like riding the sled down a steeper slope. You will go faster.


In a diving turn the centrifugal force you feel is your body in the harness being pulled to the outside of the turn and the increasing force you must resist to keep the riser pulled down and continue diving.

The practical answer to your question is that you are really looking for the most efficient arc (path) to the ground and level flight that gives you the most forward speed.

Trying to get the get the most centrifugal force by multiple spirals is unnecessary. The more you increase the centrifugal force the more piloting inputs you have to give the canopy to steer your momentum to straight and level flight which inefficiently uses up the momentum you generate by spiraling many times.

You want to get the most forward speed which is ultimately dependant on drag, wingloading, wing shape and trim. The longest swoop was on a velocity over 100 sq ft w/ a single 270* turn to level flight. Having built momentum in the turn, the actual swoop involves managing that momentum w/ the flare or lack there of.

Ken

"Buttons aren't toys." - Trillian
Ken

[quade 4]

Quote

If you increase the angle of attack it is like riding the sled down a steeper slope. You will go faster.

That should read, "If you decrease the angle of attack . . . "

quade -
The World's Most Boring Skydiver

[Ron 10]

Angle of Incidence is usually set by the aircraft design.
They do not change on fixed wing aircraft. It is determined by the difference in angle of the thrust line, vs the center of the wing.

Canopies have a cool feature in that the AoI can be changed.

But by changing the AoI with a canopy....the Angle of Attack which is the center of Airfoil in relation to the relative wind, also changes....

It is changing the AoA that makes the canopy go faster.

As for what Quade said about Drag...he is correct. I hinted at it in my first post, but looking back at it it was not communicated as well as I liked.

Drag increases as a square of the airspeed. As the airspeed increases the drag increases exponentialy.

As you and your best friend "Super Swooper Canopy X" Start to turn you increase the AoA of the canopy. The "Super Swooper Canopy X" and you both start to speed up. As the speed increases, the drag increases on both you and your "Super Swooper Canopy X". This dive will continue until:

A. The drag on the canopy increases to be more than the drag on your body. This will cause your body to continue to speed up at a rate that the "Super Swooper Canopy X" cannot keep up with. Then since you are going faster than the canopy, you will start to swing out from under (relative term here, since the canopy will most likley be beside or below you realtive to the horizon at first) the canopy.

B. You stab your brakes in a last ditch effort to not become one with "Terra Firma" and join the "Femur Club". When you stab your brakes you increase the drag on the canopy and this lets you speed up faster than the canopy, sooner.

C. You hit the ground and Die.

Sorry could not resist "C" again.

Ron...

PS. on a really funny note the Fantasy of Flight swoop meet.
Very high winds. 8 jumpers left, all flying over 2 to 1 wingloadings...
1 landed off with a minor pilot chute problem.
1 landed dry....having never even touched the water.
1 managed to touch the water, and get out of the pond via the side.
5 made REALLY cool splashes....I have photos.
It was then canceled.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334