So Brian Germain got me thinking...

[millertime24 8]

I was reading the book "the Canopy And Its Pilot" and in it Brian explains that the reason humans under canopy cant land at the wl'ing aircraft do is because a/c have wheeles for landing gear. I was wondering, would it be possible to land a canopy w/l at about 5-1 if one were wearing rollerblades or something? Is this possible?

Muff #5048

[Calvin19 0]

I don't think landing gear is the thing. I think the reason we can't jump smaller canopies effectively is because we have a fixed amount of parasite drag cross section.

-SPACE-

[shveddy 0]

4.74 lbs/sqft

clicky

Anyone know what luigi loaded his 37 at?

[Skydivesg 6]

I'm not sure what his wing loading was but I onced watched Robin Heid land with roller blades.

Didn't work out so well for him.

Be the canopy pilot you want that other guy to be.

[davelepka 4]

Yes, you could. The problem with higher wl is that the stall speed increases as the wl goes up. Once the stall speed is above running speed, you have a problem.

If you watch Luigi on the 37, you'll notice he does quite a bit of 'flintstone' braking, where he slides his feet along as he surfs. What's he's doing is transfering his weight from the canopy to his feet. As he applies more weight to his feet, the wl on the canopy goes down and in turn the stall speed goes down, and the canopy keeps flying (and supporting the rest of his weight) a little longer. Even then, you'll notice that toward the end of the swoop, the canopy will buffet and stall as he begins to take his first (very large) steps.

So yes, if you could run (or roll) fast enough, you could jump at higher wl. How high is another story. At some point, the stall speed will be so high that the canopy won't be able to maintain level flight for very long. As soon as you pitch the nose up to level off, you immediately being to lose airpspeed. If the stall speed is just slightly under full flight, your 'window' for planing out and getting your 'wheels' on the ground is very slim.

Let's also remember that most airplanes have flaps, which alter the goemetry of the wings to allow them to fly slower (both the top speed and stall speed are reduced) and these flaps are usually used on landing. Smaller planes liek jump planes and other prop aircraft can be landed without flaps, but most of the time some degree of flaps are used to slow down the touchdown speed.

Airplanes with higher wl, like jets, will sometimes have flaps that extend back from the trailing edge and slats that extend forward from the leading edge to really slow the wing down. These types of planes rely heavily on the flaps to control the landing speeds, and almost never land without them.

So even though planes do land at higher wl, even then there are special considerations made.

[NWPoul 1]

We have them (flaps) too :)

Why drink and drive, if you can smoke and fly?

[davelepka 4]

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We have them (flaps) too :)

Kind of, sort of, and not really.

Flaps on an airplane effectively increase the wing area, and accordingly decrease the wing loading which, as we know, also decreases the stall speed. I think the technical name for them is Fowler flaps, and they actaully extend to the rear as well as deflecting downward, and it's this rearward extension that provides the increase in wing area.

When you pull down the toggles on your canopy, there is no rearward extension, only downward deflection so there is no increase in wing area.

Also, when you deploy the flaps on an airplane, you retain control of the pitch attitude via the elevator. The flaps only control the airspeed aspect of the aircraft, and while they do have an effect on the pitch attitude, the pilot can counter that. As such, the pilot retains the ability to flare the aircraft seperate from the flap deployment.

With a canopy, the tail deflection provided by the brakes is more similar to the elevator of an airplane. Unlike with flaps, you do not have continued control of the pitch attitude after you have employed the flaps. Pulling the brakes causes the canopy to slow down due to the drag of introducing the tail into the airstream and from the increase in drag due to the increased angle of attack as the nose pitches up.

With an aircraft, the flaps are deployed well before the flare (ideally), allowing the airspeed and pitch attitude to stabilize well up the final approach. Now the airplane is a different flying machine, with a slower top speed and a slower stall speed, just what you want when you're landing.

I have thought long and hard (as I'm sure may others have) of a way to incporporate an actual flap system into a canopy. I ran into several problems, with the majority of them being related to swooping.

Non-swoopers have no use for flaps. Indeed it would allow them to fly at higher airpseeds up high and then slow it down for the landing approach, but you could get the almost the same result by just developing the skills to fly a faster canopy and then downsizing.

So now we're left with the swoopers. The only way a flap system would work is if it could be deployed at some point during the swoop itself. You would want the canopy to fly in the high speed configuration during the approach, the actual turn itself, and the early part of the swoop. Once you approached the stall speed of the high speed configuration, you would deploy the flaps, and switch the canopy to a low speed configuration. Now you have a canopy with a lower stall speed (which would fly further and longer before reaching that speed) but you would retain control over the canopy with your risers/toggles.

The idea is very similar to using the rear risers to land. You begin your swoop with the rear risers, whcih provide less drag but have a higer stall speed. Once you apporach that speed, you transfer to toggles which may introduce more drag but with a lower stall speed. So where the rears were getting ready to stop flying, the toggles have another chunk of airspeed to go before the canopy is ready to stall.

The only way to do 'flaps' on a canopy would be some sort of trim tabs, probably on the front risers. The trim would be steep as hell for the high speed configuration. It would allow the canopy to dive longer and build more speed. Once you build that speed, and get the canopy down on the deck, you would release the trim tabs, and allow the front risers to extend. Now the canopy would be trimmed flatter, which would allow you to fly further with less input. The distance you went before adding input would be the benefit of the system.

The major problems, and they are major, are twofold. One, is how to activate the system itself at the right time. It would be at a busy time during the swoop when the pilot is already busy and has both hands occupied. The other is that if the release wasn't symetrical in any way, now you're on the deck going fast as hell with a canopy with a built in turn of some degree. This is why the flaps on an airplane are deployed well up the final approach - the pilot has the time to do the work, and if there is a problem, they have the altitude to do a go around or otherwise deal with the problem.

[Couloirman 0]

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I was reading the book "the Canopy And Its Pilot" and in it Brian explains that the reason humans under canopy cant land at the wl'ing aircraft do is because a/c have wheeles for landing gear. I was wondering, would it be possible to land a canopy w/l at about 5-1 if one were wearing rollerblades or something? Is this possible?

Ive done a rollerblade groundlaunch before and I think its definitely possible to land a much smaller canopy than you could land on your feet.

That being said, I wont be doing it again because I have no business being on rollerblades going that fast and I almost ate it onto the pavement. Ski's on the other hand...

[matt002 0]

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The only way to do 'flaps' on a canopy would be some sort of trim tabs, probably on the front risers. The trim would be steep as hell for the high speed configuration. It would allow the canopy to dive longer and build more speed. Once you build that speed, and get the canopy down on the deck, you would release the trim tabs, and allow the front risers to extend. Now the canopy would be trimmed flatter, which would allow you to fly further with less input.

Sounds like you're describing turns using both front risers

[davelepka 4]

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The only way to do 'flaps' on a canopy would be some sort of trim tabs, probably on the front risers. The trim would be steep as hell for the high speed configuration. It would allow the canopy to dive longer and build more speed. Once you build that speed, and get the canopy down on the deck, you would release the trim tabs, and allow the front risers to extend. Now the canopy would be trimmed flatter, which would allow you to fly further with less input.

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Sounds like you're describing turns using both front risers

No. When you use both fronts, you do re-trim the canopy for higher airpseed and a longer dive, which is good, but as soon as you release the risers you return the standard trim of the canopy, which in terms of utilizing speed is bad.

To really equate to a 'flap system' you would need to be able to take advatage of the high speed configuration into the swoop (plane out) itself, and then switch to the low speed configuration.

Any inputs you apply to a standard trim canopy during the apporach/turn itslef is just a regular swoop on a regualr canopy. You can achieve greater speed/range by simply becoming a better pilot and flying a better approach/turn.

The idea of a 'flap system' and building a canopy with a high speed config and a low speed config is taking it to the next step. If the pilot is already performing at 100%, the 'flap system' would serve to offer a canopy with a greater speed range.

Even then, it would be up to the pilot to perform at a level high enough to take advantage of the new capability of the canopy, which in itself might actaully be another 'problem' to add to the others I outlined in the other post.

All in all this is really just theoretical, as the idea itself goes against the grain of so many basic rules of safety. The old 'keep it simple, stupid' principal is one that always seems to come out on top in skydiving, and any sort of in-flight canopy retrimming system would be anything but simple. Beyond that, the idea that it would need to be operated (and counted on) at a very critcal phase of flight (low altitude, high speed) makes it a bad idea in general.

I would be VERY interested to see anything close to this anyone has built or tested (even at high altitudes) and even more interested to see the guy with the giant nutsack who would actaully swoop with it.

[Calvin19 0]

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To really equate to a 'flap system' you would need to be able to take advatage of the high speed configuration into the swoop (plane out) itself, and then switch to the low speed configuration.

I would be VERY interested to see anything close to this anyone has built or tested (even at high altitudes) and even more interested to see the guy with the giant nutsack who would actaully swoop with it.

It has existed for years in paragliding. only WAY better. and in speed flying.

it is complicated in a PG rig, but on a simple 4-riser Ozone Bullet paraglider there is 'trim tabs' on the front risers, when pulled in they create an airfoil with a lower angle of attack, making the lift vector of the glider angled farther away from the gravity/weight vector. this allows for much higher speeds in maneuvering and longer dive recovery.

in PG as well as PPG (paragliding, powered paragliding) nearly all gliders have a acceleration system, and it is a very refined AOA control system, instead of the extremely crude and inneficient "front riser input" of a skydive canopy, it contours the entire airfoil of a glider for less AOA. here is a good example of the accelerator system:
http://en.wikipedia.org/wiki/Paragliding#Control

On most PPG gliders, there are trim tabs in the aft section of risers, and function in reverse of trimmers on a speed glider by increasing the AOA uniformly across the glider and allowing slower launches and landings with a heavy motor.

Someone was trying compare aircraft flaps earlier, it does not work like that. we are flying kites on strings, the aerodynamics are very different from conventional aircraft. there is much less "positive control" of the airfoil.

-SPACE-

[millertime24 8]

Thanks for all the input and very in detail canopy and aircraft flight characteristics. I was more thinking that if one were to completely not use the brakes at all how well would the stunt work if you used the rear risers to increase the AOA of the canopy, but not deflect the tail? Would that not enable you to retain a much higher airspeed hence giving you greater lift?

Muff #5048

[davelepka 4]

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It has existed for years in paragliding. only WAY better. and in speed flying.

Yes, it has, but it's not really used in the manner I was discussing. I've flown speed flying wings with the trim tabs on the riser, but my impression is that they are not intended for use during flight, or if they are, it's only for adjustment at non-critical phases of flight (as-in not close to the ground at high speeds).

Although I'm not familiar with the details, I know that paragliders take it even further, but again, these systems are more complex, and not designed for adjustment mid-landing.

There are all sorts of things you could do with a canopy up high. CREW guys have used trim tabs on front risers for years, and I know a couple of CREW camera guys who use toggles on their feet attached to the front riser to allow them to stay with formation without bruning out their arm muscles.

What I'm talking about is an adjustment that could be made to shift from a high speed config to a low speed config mid-swoop, to allow the swooper to take advatage of that speed range and convert it to distance.

Everything you can do at altitude doesn't really interest me. If I want to go faster, I'll jump smaller canopy. If I want to go slower, I'll jump a bigger one. In either case, I'll be making a comprimise when it comes to my swoop, but that's life.

Now if there was a way to extend my swoop, now you're talking. Better yet, what if you could deploy and fly back to the DZ in a low speed config, shift into the high speed config for the dive and first part of the swoop, then switch back to the low speed config for the extended swoop and shut down, that would be the best. I could get out last with a tandem video, make it back to the DZ, and lay down 500 footers all day long. It's fun to dream.

[davelepka 4]

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I was more thinking that if one were to completely not use the brakes at all how well would the stunt work if you used the rear risers to increase the AOA of the canopy, but not deflect the tail? Would that not enable you to retain a much higher airspeed hence giving you greater lift?

I'm not sure what you're getting at, but increasing the AOA of the canopy will increase drag, regardless of what input you use. Rear risers may induce less drag, but there is a drag pentaly none the less.

Also, keep in mind that increasing the AOA on a canopy also has the affect of reducing thrust. Canopies use gravity to create thrust, and they do it by virtue of their trimmed glide angle, whatever that may be. It's essentailly the hill the canopy is flying down. When you increase the AOA (nose up) the grade of the hill is reduced, and so it the speed (thrust) the canopy will have in going down that hill.

To a degree what you are saying is the reason swoopers start off on the rear risers. They do operate in a higher speed range than the toggles, and at the outset, will provide a greater lift at a smaller drag penalty. Eventaully, you are pulling so much of the rear half of the canopy into the airstream, that the drag level increases very rapidly, and you apporach the stall.

Keep in mind that when you pull in the rears, it's not the entire wing pitching up the AOA. The canopy from the A lines back to the B line does not move, it's the canopy from the B lines back that is introduced into the airstream. So in addition to creating drag, you're deforming the wing along the chord line.

In theory, if you didn't have B lines, or if the B lines were attached to the rear risers, you could apply rear riser input, the AOA would pivot around the A line attachment point, leaving the wing more intact during the input. Of course, this would create all sorts of other problems, but it would eliminate the chord-wise distortion you get with rear riser input.

The basic idea is that with an unpowered craft with only one flight mode, there is no free lunch. If you want to build a faster canopy, it will be fast in both high speed flight and low speed flight (as in a high stall speed). If you build a slow canopy, it will be slow across the board, especailly when setting it down in the middle of the peas.

This is why airplanes have flaps, slats, and in some cases moveable wings (think F-14 or B-1 bomber). In order to make these planes do everyting the mission required, the size, shape and position of the wing needed to change mid-flight to achieve those requirements. To get a plane the size and weight of an F-14 on and off of a carrier, and then have it break the sound barrier in between is quite an accomplishment, especially 40 years ago when it was designed.

[Calvin19 0]

I figured you knew about that.

in old PG design, there was ideas for full-flying risers, meaning the riser was infinitely adjustable. (meaning that the AOA of the glider was infinitely adjustable).

the only control in paragliders and parachutes is camber, and a small amount of indirect AOA control.

for the most part, brakes are very inefficient as swoopers have figured out long ago and started using front and rear riser input as much as possible.

If you want the MOST efficient control, you will have to abandon the illusion of simplicity.

the secret to better swooping is 1-even span and cordwise camber control, 2-less line, and in my opinion, a 3- smaller cross section harness.

The only problem with swooping is you have to involve a parachute.

[Calvin19 0]

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This is why airplanes have flaps, slats, and in some cases moveable wings (think F-14 or B-1 bomber). In order to make these planes do everyting the mission required, the size, shape and position of the wing needed to change mid-flight to achieve those requirements. To get a plane the size and weight of an F-14 on and off of a carrier, and then have it break the sound barrier in between is quite an accomplishment, especially 40 years ago when it was designed.

yeah, but like I said, the problem here is your dealing with parachutes.

I have worked on a variable geometry ram air canopy before, it is very difficult. and it was not even used for freefall.


here is a very old version of something I was working on. there is other stuff in here that might be of use.http://www.expandingknowledge.com/Jerome/PG/History/Strange/Image/WING_SurfaceReduction_Center_PG_1998_09_p45.jpg




Paragliders, while the goal is much more efficient flight than getting a ton of speed and skidding across the ground for the longest distance, aerodynamics of ram air gliders cross over to both sports.

http://www.expandingknowledge.com/Jerome/PG/History/Strange/Album.htm


I think the way swooping should go is get away from the sport of skydiving.

[davelepka 4]

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yeah, but like I said, the problem here is your dealing with parachutes.

Of course. All of the aircraft info was just for reference, in reality ram air canopies are very limited in their capabilities. If you look at early ram air wings, and the JVX, they are more alike than they are different. Same concept, just different shape and materials.

The real problem is the deployment. In creating a wing that can withstand the deployment, and be reliable in the deployment, you really put up a lot of barriers in other areas. It's a life-saving device first, and fun-creating device after that.

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I think the way swooping should go is get away from the sport of skydiving.

While it would open up some possibilities, the general idea in swooping is to go as fast as possible close to the ground. Because of this, you have certain limitations in terms of safety and reliablilty that you would be wise to heed. Keep in mind that the state of swooping today is a 20 year long progression from toggle whipping a Sabre or PD 9-cell to where we are today. If you want to rewrite the rules by making a major change to the game, those can be dangerous waters.

I'm not exactly sure what you mean by getting away from skydiving, but if you're suggesting that swooping should be based on some ground launched basis, I have to disagree. This is based mainly on the fact that I live in Ohio, where the land is as flat as can be. Without a plane, there's no where in the state you could get enough altitude for me to 450 my Velo, and I'm not ready to accept that.

[Calvin19 0]

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If you want to rewrite the rules by making a major change to the game, those can be dangerous waters.

I'm not exactly sure what you mean by getting away from skydiving, but if you're suggesting that swooping should be based on some ground launched basis, I have to disagree. This is based mainly on the fact that I live in Ohio, where the land is as flat as can be. Without a plane, there's no where in the state you could get enough altitude for me to 450 my Velo, and I'm not ready to accept that.

Very dangerous waters, but I have no interest in swooping.

It's the aerodynamics that appeal to me. innovative engineering.

I like relative motion, (not playing chicken with the ground on a swoop)

-SPACE-

[millertimeunc 0]

Interesting discussion, and if I may be allowed to throw my 2 cents in...

Dave, you're right on the money. In my jet, we use both trailing and leading edge flaps to get the final approach and landing speed as low as possible. The reason for this is that, as heavy gross weights (analogous to high wing loadings on a canopy) we are concerned with tire placard speeds and the ability to land without damaging the gear and other aircraft components, as well as controllability issues (higher approach speeds = twitchier and higher probability of over controlling and ballooning in the flare).

The same laws of physics apply for canopies. Sure, you could have a greater wing loading, but the question is what will your ground speed be in the flare when your wing runs out of flying airspeed? If it's faster than you can run, you're in trouble. Roller skates *might* work, but would you want to try it? I'd think that the drag from the stalled canopy would drop you on your ass as soon as you touched down, so no thanks!

The best things in life are dangerous.

[piisfish 135]

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It's the aerodynamics that appeal to me. innovative engineering.

do you think the carbon inserts and the minimalist lineset like in the Ozone BBHPP would be an option (if they could survive a packjob and an opening) ?

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[rhys 0]

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in old PG design, there was ideas for full-flying risers, meaning the riser was infinitely adjustable. (meaning that the AOA of the glider was infinitely adjustable).

the only control in paragliders and parachutes is camber, and a small amount of indirect AOA control.

for the most part, brakes are very inefficient as swoopers have figured out long ago and started using front and rear riser input as much as possible.

If you want the MOST efficient control, you will have to abandon the illusion of simplicity.

I really don't understand what you're saying there, from my research (not too extensive, that is why I am discussing), paragliding speed flying canopies (nano, bullet etc) and paragliders will be more inclined to 'frontal' collapse with a substancial amount of front riser input?

They have speed bars and trim tabs etc. but those are calculated to remain within a stable position and not exceed? any more input than that would be potentially fatal?

That is why you see 'speed fliers' using toggles and 'ground launchers' using risers?

Please correct me if I am wrong, but that is how I see it and being a swooper I will be inclined to fly with risers, until a point where parachutes are proven to fly faster without!

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[davelepka 4]

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I'd think that the drag from the stalled canopy would drop you on your ass as soon as you touched down, so no thanks!

If you allowed the canopy to actually stall, that would just be pilot error. If you touched down (even on roller skates) before it stalled, it wouldn't stall because the WL would drop off dramaticly once your weight was on your skates. You would have to shift your focus from piloting the canopy to kiting the canopy.

If you watch the videos of guys landing on the back of a truck or boat, any situation where the pilot stops moving but the canopy still has airspeed, you'll see that they imediately put the toggles all the way up and some times even apply just a touch of double front risers to keep the canopy flying and overhead.

[davelepka 4]

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paragliding speed flying canopies (nano, bullet etc) and paragliders will be more inclined to 'frontal' collapse with a substancial amount of front riser input?

Best guess on paragliders would be the flat trim with less weight hanging on the front risers. Also, I would have to think that the high aspect ratio isn't helping either. If you think about the difference between the span and the chord, pulling a riser will have that massive span being pulled down against the short chord. If sort of makes sense that you could overpower the chord and fold the leading edge under.

As far as speed wings go, I'm not sure. I know they have trim tabs, but what I don't remember is if the canopy is trimmed flat and the tabs make it steeper, or the other way around. Either way, when in the flat trim config, it would be the same as the PG canopy, with light front risers and rearward weight bias.

In terms of the aspect ratio, they're similar to skydiving canopies, so that shouldn't be a factor. It's possible that the manufacturers are used to that condition (they do build the PG canopies) and never sought to address it. If they're building these as an offshoot of PG, they're probably doing it using PG type techniques in mind.

[millertimeunc 0]

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I'd think that the drag from the stalled canopy would drop you on your ass as soon as you touched down, so no thanks!

If you allowed the canopy to actually stall, that would just be pilot error. If you touched down (even on roller skates) before it stalled, it wouldn't stall because the WL would drop off dramaticly once your weight was on your skates. You would have to shift your focus from piloting the canopy to kiting the canopy.

If you watch the videos of guys landing on the back of a truck or boat, any situation where the pilot stops moving but the canopy still has airspeed, you'll see that they imediately put the toggles all the way up and some times even apply just a touch of double front risers to keep the canopy flying and overhead.

Ah, that makes sense. You learn something new every day!

The best things in life are dangerous.

[davelepka 4]

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Ah, that makes sense. You learn something new every day!

You already knew that, you just didn't apply it to parachutes.

In your jet, you don't corss your arms and put your feet flat on the floor once the wheels touch down, you keep flying (driving?) the plane. I'm sure you're on top of it until you set the parking brake, but you especially pay attention until you're slow enough to get on the brakes and stop the thing in less than 50 ft.

Same thing with a parachute. If you're moving fast enough (or there is enough wind) that the canopy can still lift all (or most) of your weight, you need to keep 'flying' the canopy.

It's not just for swoopers either, after you land on a windy day, you need to fly the canopy into the ground and make sure it's contained before you take your attention away from it.