REAR RISER FLARES

[SHARKY 0]

I've just being watching Swoop, awesome video! Awsome landings (well most anyway)
I was trying to see if the top guys were using rear risers for coming out of the dive and you can clearly see that some of them are. I am seriously considering giving this a go on my Xaos 83(at altitude first) but am not sure at which point to start the flare and where to transition to toggles.
On the video some seem to go on toggles whilst still in the dive where as one swooper seems half way accross the lake before he releases the risers.
This must make a difference to performance or you guys would not be doing it.
May your swoops be long!

[SkymonkeyONE 3]

Actually, that transition point varies from jumper to jumper and even from jump to jump by individuals. What you mainly use the rear risers for is to get you "around the corner." Some people will transition to toggles as soon as they are planed out in ground effect, others will milk their rear risers out to as close to the stall point as possible. You have to be very careful if you choose to do the latter because your canopy will abruptly stall at a quite-high airspeed on rear risers. Pull or push them a half inch too far when near that velocity and you will end up flat on your back in a very violent fashion. I have seen the great majority of my fellow competitors eat it badly on rear risers while perfecting their technique. On the other hand, some of them are VERY adept at rear riser flight and have no problem flying right through curving courses with them, only transitioning to toggles once they fly out the back; very nice.
Chuck
My webpage HERE

[SwoopMenace 0]

Hey Sharky,
I noticed from another posting that you jump in the U.K. Well, I run a canopy flight school at Hinton. I'm flying a VX 79 and I use rear-risers on landings. The most important thing to remember when wanting to use rear-risers is UNDERSTAND wing aerodynamics fully! I say this because the concept of rear-riser landings is pretty simple when you understand how a wing works. By that I mean when you use your toggles to pull out the dive you are creating MORE lift over the wing BUT also more drag. When you use rear-risers you are changing the wing's angle of attack (same affect - coming out the dive) BUT you don't add the extra drag. This means a more efficient swoop. Believe me, my swoop distance has improved monumentally since i have been landing on risers.
The next thing i know you are asking is, at what point do you try this near the ground? Well, as i said before, rear-risers (RR) don't add lift. This means that should you turn in lower than normal and need to 'dig' out, using RR is a death-trap! With no extra lift and your increased weight in the harness due to pulling out the dive (pulling more Gs) your canopies stall speed will increase. This is the case regardless of whether you use toggles or RR. BUT with toggles the extra lift means there is less chance of the canopy stalling out on you. With RR it will be hard and fast. Stalling out your canopy on the horizontal on RR is one thing but trying to 'dig' out with RR will get you a toe-tag!!
The next difficult part is knowing when to come off the RR and onto the toggles. You can't do the whole landing on RR. The benefit you gained from coming out the arc with no drag will be more than lost by you stalling at a high speed (no extra lift remember?) So you need to know when the optimum time in the swoop is, to transfer over to toggles to increase lift for the slow-speed portion of the swoop. It's dependent on the canopy but I'm doing around 75-80% of my swoop on RR. This then brings in the last complication. Moving from RR to toggles without getting dumped into the ground. Yet again this is where your high altitude testing area comes back in.
I would say, practise up high simulating a dive/swoop and going onto your RR without having to look for them. Then try the whole swoop on RR and see the effect when it stalls - not pretty! Get used to the change over from RR to toggles. Only when this is second-nature should you try it near the ground - particularly as i know you have no pond.... ;o)
If you want to talk in depth about this, please contact me, Tim Carter, at Hinton skydiving centre.

[RichM 0]

Sounds like a trip to Hinton is in order this summer. Tim, what format does your schooling take and what are the costs? Also, what are the costs at Hinton come to think of it :)
My email is [email protected], regular dz is Headcorn and sometimes to be found Sibson.
Rich M

[prost 0]

How much of a difference in distance do you think landing on rear risers makes?
William

[freeflyguy 0]

Nice post Tim

[rogue108 0]

Excellent post Tim

[SwoopMenace 0]

Basically, RR landings will ONLY benefit you if your recovery arc placement is bang on the money. By that i mean, NOT low! This may sound obvious but RR are VERY sensitive and have a VERY narrow control range. If you've put yourself in a position where you think you will have to use your RR outside that control range then the swoop will suffer severely or worse.
An example of a catalogue of small errors would be you have initiated your dive and you are a fraction on the low side. Here's 2 scenarios : -
a) the jumper using toggles will give more input coming out the dive to get round the corner.
b) the jumper learning RR will start on his RR and as he is pulling out the dive, as there is no drag, it feels like you are accelerating towards the ground because basically, you may not know it, but when you flatten off with toggles you are slowing yourself a little. Suddenly, the jumper realises he won't be able to pull out this corner on RR and has to get on toggles by which point he is now probably too low for toggles to save him.
This all points to being proficient on your altitude judgement and being able to judge even better than normal if you are gonna use RR coz you need to get off real quick if you think your low.
I have 2 good bits of advice (from experience!)
1) If you are in ANY doubt whatsoever as you are in or coming out your dive as to your altitude get off the RR and get on toggles. (better to be safe)
2) when using RR don't spread the RR outwards as the canopy will get very unstable. I recommend pulling them straight down BUT with a twist in the wrist. By that i mean, the last thing you want is a riser to slip out your grip!! With a twist it locks the riser in the hand better.
Finally, In answer to your question, I have video from my team mate of me clocking a 370ft swoop on a measured course at Lake Wales Florida! (12mph downwind)
You can expect average 30% increase to your swoops

[SkymonkeyONE 3]

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2) when using RR don't spread the RR outwards as the canopy will get very unstable. I recommend pulling them straight down BUT with a twist in the wrist.

While the "pulling" and "twisting" methods are both fine, you cannot arbitrarily dismiss the "pushing" method. Hell, some people end up doing something that resembles both; Jay Moledski for example. Bottom line is that it all comes down to what works for the individual. On the PPPB tour, it's split pretty evenly among the two types. Personally, I loop my thumbs over the riser and push. This allows me to just "pop" off at the transition velocity and keep on trucking; it's very smooth. Yes, symmetry is important, but that goes for whatever method you use. In a straight course, whether Speed or Distance, hooking thumbs and rolling forward in your harness will keep you straight. In a curved Speed course, rolling your wrists and pulling might work best for most. Watch video of Heath Richardson, Jim Slaton, and J.C. for good examples of carving on rear risers.
Some people have problems dropping their toggles on transition when using the pull method; I have seen MANY a competitor eat it badly due to pulling one inch too far on one side. Going along with that: if you are going to start rear-risering and you currently have trips, then you probably want to ditch them for standard risers. Standard risers maintain RR deflection even upon transition to toggles, assuming you flare to the outside like I do.

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I have video from my team mate of me clocking a 370ft swoop on a measured course at Lake Wales Florida!

Through five foot gates? That is the official PPPB measurement standard. World record through a real course is 340 feet by Clint Clawson at the first PPPB Perris meet last year. If you are throwing 370 feet you need to be over here competing. The more the merrier in my opinion!Chuck
My webpage HERE

[SwoopMenace 0]

Yeah Chuck, I know that! :o) Unfortunately mine was on 10ft entry gates. More of an example of how learning to use RR really put me up a 'performance category' so to speak!
I am hoping to come out to the meets next year. Look forward to seeing you guys there.
By the way, did Clint get the 340ft under 5ft gates? I heard 'rumours' that it was under higher gates and THEN they changed the entry gate size. Maybe so no-one can touch their records? But it could be just rumour.... ;o)

[SkymonkeyONE 3]

That was the first meet in which we used the short five-foot gates, and yes, he flew 40 feet out the back of the 300 foot measured course. They had to get a tape measure to record the rest of the swoop! Nobody believed that anyone would fly out the back with five foot blades, so that is as long as the course was set up. All the blades after the four five-foot entry blades were either 14 or 12 footers and you were penalized if you touched them.
The previous record, 328 I think, was set the previous year by J.C. Colclasure through 14 foot entry gates.
Current PPPB distance courses go out WELL beyond 300 feet now (just in case) and the five-foot entrance standard has been in place since June last year at the first Perris meet.
My webpage HERE

[SHARKY 0]

Thanks for the well explained info Tim. You say you run courses at Hinton, are these on a regular basis? I was trying to get to the one that Chris Lynch is running at Headcorn but that bitch called work has prevented me from getting there.
If you have any planned could you let me know the dates (my e-mail is [email protected]), i could fancy a weekend at Hinton. I think with all the coaching roadshows the BPA are running and with more jumpers in the UK now getting higher performance canopies there should be more info and coaching available.
Until then i guess its a case of taking it gradually and practicing up high.
One other point, is it because of the additional speed created with a riser turn that the canopy is easier to stall on RR, my point being that if you are coming back from a long spot you can hang off the RR without any danger of stalling the canopy.

[SwoopMenace 0]

Ok Sharky,
Important rule no.1 : Speed equals Lift.

- The faster you (your wing) is going through the air the more lift you have to 'play' with and the more 'control' you should have. (Compare landing straight in on full-glide and landing on half-brakes and trying to get a decent flare)
2) When flying straight (from a deep-spot) using RR you are hanging at 1G in the harness. 1G of your weight in the harness on your canopy size using RR will have a stall speed of x. When pulling hard out of a dive on RR you are hanging (for arguments sake) 3Gs in the harness therefore your RR stall speed will be 3x - basically MUCH higher (this is NOT accurate physics but indicates the fundamental theory...)
There is one other factor that skydivers have to contend with which solid wings don't have and that is when we (skydivers) pull a very hard negative angle of attack (as in over doing the RR) we deal with wing deflation. A solid wing will stall but will become 'operational' before a parachute.
That aside, if you treat your parachute like a wing and understand and respect the laws of aerodynamics you 'shouldn't' have to worry too much about the last bit.
Remedie : 1) fly straight (up high) on RR and keep changing AoA until it stalls.
2) bust a hard front riser dive and pull out hard on RR until stall, observe the difference. At what speed did the wing stall in straight flight compared to a dive (increased speed AND harness weight)? was one more abrupt than the other?
Take care everybody,
Remember, knowledge is power...

[hookit 0]

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Important rule no.1 : Speed equals Lift.

Oh shit. Here we go again! Quick, everyone run for cover before Quade sees this!

[Kris 0]

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Important rule no.1 : Speed equals Lift.

Awwwww, dammit! Somebody hide Quade's pocket protector so he'll be late and hopefully miss this thread!Kris

[RichM 0]

Hehe, I'm still a newbie here, and I'm looking forward to Quades response :) I have lots to learn and these sorts of points keep that education flowing. "Let's get it on!"
Rich M

[PhreeZone 14]

just do a search of airspeed equals lift.... that one is a tired argument. Basically there is more then just speed in lift.
If once you start down the dark path, forever will it dominate your destiny, consume you it will....

[billvon 2,380]

> The most important thing to remember when wanting to use rear-risers is
>UNDERSTAND wing aerodynamics fully! I say this because the concept of rear-
>riser landings is pretty simple when you understand how a wing works. By that I
> mean when you use your toggles to pull out the dive you are creating MORE lift
> over the wing BUT also more drag. When you use rear-risers you are changing
>the wing's angle of attack (same affect - coming out the dive) BUT you don't add
> the extra drag.
You add drag when you increase AOA to increase lift. Toggles change AOA and increase both drag and lift; rear risers do the same thing. Since they both impart different shapes to the wing, they both increase AOA in slightly different ways. In many canopies, rear risers are a more efficient way to trade airspeed for lift.
>The next thing i know you are asking is, at what point do you try this near the
> ground? Well, as i said before, rear-risers (RR) don't add lift.
Pulling down on your rear risers increases your AOA, and thus increases your lift. That's why it is possible to momentarily reduce a canopy's descent by using rear risers.
>This means that should you turn in lower than normal and need to 'dig' out,
>using RR is a death-trap!
Agreed.
>With no extra lift and your increased weight in the harness due to pulling out the
> dive (pulling more Gs) your canopies stall speed will increase.
You cannot pull more G's without increasing lift. Lift is the only thing keeping you in the sky. To pull two G's you need twice the lift.
>This is the case regardless of whether you use toggles or RR. BUT with toggles
> the extra lift means there is less chance of the canopy stalling out on you.
Well, canopies are designed to give you the best possible slow-flight lift (i.e. stall as late as possible) when using toggles. You could easily design them to do that with rear risers instead; in fact, paragliders use a very efficient method of pulling on _all_ the linesets to smoothly change the AOA. This system, applied to a skydiving canopy, would give you an awesome swoop, but would be complex.
I agree with your descriptions of how to land a canopy, but I would be leery of drawing new conclusions based on the above aerodynamics.
-bill von

[freeflyguy 0]

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Speed equals lift.

Funny. All along I thought the heat generated from my parachute going faster is what caused the extra lift. Learn something new every day. :)
Bill, I have to diagree, Toggles do change the shape.
Rear risers only change the angle of incidence, they don't change the shape of the wing. Angle of incidence cant be changed on a fixed wing aircraft, unless you are willing to get out the air chisel, but we don't fly a fixed wing.
You are right in saying that the rears do cause an increase in drag, because of the increase of A of A, but not near as dramatically as the toggles do.

[polarbear 1]

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There is one other factor that skydivers have to contend with which solid wings don't have and that is when we (skydivers) pull a very
hard negative angle of attack (as in over doing the RR) we deal with wing deflation. A solid wing will stall but will become 'operational'
before a parachute.

Right. Parachutes are designed with the stagnation point in front of the cell mouth. When the AOA is changed, the stagnation point migrates...if it migrates off the cell mouth (to the upper or lower surface) air will flow across the mouth instead of into it. This will effectively suck the air out of the cell and collapse it.
This translates to piloting parachutes as if you change the AOA too much, you invite a collapse. I haven't managed to do it with front risers on any canopy I've flown, but there are A LOT of canopies I haven't flown. You can collapse a canopy with toggles, but I think this is because the forward speed gets reduced to zero/negative, not because the stagnation point has migrated off the cell mouth. I haven't ever tried it with rear risers.

[flyhi 24]

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Right. Parachutes are designed with the stagnation point in front of the cell mouth. When the AOA is changed, the stagnation point migrates...if it migrates off the cell mouth (to the upper or lower surface) air will flow across the mouth instead of into it. This will effectively suck the air out of the cell and collapse it.

Excellent point which I hadn't even thought of until you mentioned it.
What is the affect on airlocked canopies?
flyhi

[billvon 2,380]

>Bill, I have to diagree, Toggles do change the shape.
Agreed, they increase a wing's camber in one area. I don't think I ever disagreed with that.
>Rear risers only change the angle of incidence, they don't change the shape of
>the wing.
Well, no. Take a look at a canopy being flown in rear (or front) risers. The A/B lines move independently of the C/D lines, so you get a stepwise change in the center of the canopy. There is an effective change in AOI but there is also a change in the shape of the airfoil. Again, if you used the "speedbar" system that a paraglider uses you could get a perfect change in trim angle, but no one (as far as I know) uses one of those.
-bill von

[billvon 2,380]

>What is the affect on airlocked canopies?
Same. The canopy will deflate. The plus is that it will take slightly longer for it to deflate, so you have a better chance of flying through the turbulence and/or correcting the AOA.
-bill von

[freeflyguy 0]

Cool. I agree with you too.
My point is the toggles are intended to change shape and camber. When you pull rears, or fronts, it does change the shape, some, because of the step, but that is only a by product, not the intent. If someone where to pull just an inch or too, the canopy's flight would alter dramatically, but the top of the canopy would change very little, or not at all. In that situation, you are not really altering the wing to make it increase it's lift, you would be mostly changeing AOI and AOA.
Splittin hairs, but a nice thread.