Forums: Skydiving Disciplines: Swooping and Canopy Control:
Riser length advantages/disadvantages Longer vs shorter

 

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trigger  (D 101390)

Oct 29, 2011, 11:31 AM
Post #1 of 34 (7933 views)
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Riser length advantages/disadvantages Longer vs shorter Can't Post

Hi guys, curiosity thing.
2 years ago ordered 23" stock upt risers with a new container.(which work well for me)
I'm curious to what mechanical advantages/effects on canopy flight/performance there are with an increase in riser length, disregarding the limitations of physical reach.
i.e moving your C of G further away from the canopy abiet only 2-3"


DaVinciflies

Oct 29, 2011, 12:53 PM
Post #2 of 34 (7878 views)
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Re: [trigger] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

It will lengthen the recovery arc by allowing the suspended mass to take more time to swing back under the wing.

Anything else?


DrewEckhardt  (D 28461)

Oct 29, 2011, 2:15 PM
Post #3 of 34 (7861 views)
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Re: [DaVinciflies] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

In reply to:
It will lengthen the recovery arc by allowing the suspended mass to take more time to swing back under the wing.

Anything else?

Even a short line set like on a Stiletto is about 10' long and 2" out of 120" isn't even 2%.


stayhigh  (F 111)

Oct 29, 2011, 8:03 PM
Post #4 of 34 (7806 views)
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Re: [DrewEckhardt] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

but going from 23 to 26 it will make the same canopy fly whole lot different tho.


trigger  (D 101390)

Oct 30, 2011, 1:43 AM
Post #5 of 34 (7778 views)
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Re: [stayhigh] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

Thanks for the replies.
Davinci, you're right as mentioned in my initial post increasing riser length does move your C of G (center of gravity/Mass) further away from the canopy thus takes more time to swing back under the wing.
But as Drew mentioned pretty neglible as were only talking about 2 to 3 inches.
Stayhigh, what are the major flight differences you experienced when increasing your riser length from 23's to 26 inch risers. Cheers T.


trigger  (D 101390)

Oct 30, 2011, 2:16 AM
Post #6 of 34 (7777 views)
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Re: [DaVinciflies] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

I think the recovery arc will stay the same as were not changing the trim of the canopy.
But do longer risers give the pilot a mechanical advantage allowing the pilot make the canopy dive for longer and increasing the initiation height, build up more speed in the dive = swoop faster/further


captain_stan

Oct 30, 2011, 9:45 AM
Post #7 of 34 (7718 views)
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Re: [stayhigh] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

Quote:
but going from 23 to 26 it will make the same canopy fly whole lot different tho.

From the pilot's perspective, it will feel different because you have raised the operational range of the toggle-stroke a few inches higher.


jjudd  (D 31065)

Oct 30, 2011, 4:12 PM
Post #8 of 34 (7650 views)
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Re: [captain_stan] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

I have noticed the openings become much twitchier. With the c of g lower smaller movements seem to influence the harness input on opening and in flight more greatly. just my experience, not fact proven by any professional research


RichLees

Oct 31, 2011, 1:55 PM
Post #9 of 34 (7523 views)
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Re: [trigger] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

for me, its a mix of muscle memory and mechanical advantage - I have got used to where the dive loops end up when I pull them down (26" risers). when I go back to 24", I have to pull 2" closer to my chest and, for me, that's harder to hold as long.

on the other hand, I can only just reach my slider to remove it so don't go too long!


Calvin19  (D 29712)

Nov 1, 2011, 8:13 AM
Post #10 of 34 (7400 views)
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Re: [trigger] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

https://www.facebook.com/...o.php?v=533573125051


RichLees

Nov 1, 2011, 11:10 AM
Post #11 of 34 (7360 views)
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Re: [Calvin19] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

I dig the video! glad you got to the slider in the end - way better than landing with the slider banging around like on a student canopy. I also wonder what it might do to your swoop - my slider popped open in the middle of a 450 on a Katana 135 and it was pretty distracting.


EppyNephrine  (F 111)

Nov 1, 2011, 11:31 AM
Post #12 of 34 (7353 views)
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Re: [RichLees] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

In reply to:
I have noticed the openings become much twitchier. With the c of g lower smaller movements seem to influence the harness input on opening and in flight more greatly. just my experience, not fact proven by any professional research

This is awesome. I, too, am pretty interested in the same question that the OP posted. So I would love to hear results from anybody that has first hand experience playing around with this; not speculation (we can all speculate).


In reply to:
I also wonder what it might do to your swoop - my slider popped open in the middle of a 450 on a Katana 135 and it was pretty distracting.

It can be more than just distracting... I was once rolling out of my turn as my rubberband that held my slider down broke. The slider shot up to just under my toggles and restricted my risers from their full range of movement. When I went to grab my rears, the input felt completely different.


RichLees

Nov 1, 2011, 2:05 PM
Post #13 of 34 (7317 views)
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Re: [EppyNephrine] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

oh, and a word about super-short risers ... WHACK! the slider slapped me on the head with 17" risers. I had to pull them down past my nipples so I only did a few jumps with them.


hparrish  (D 25090)

Nov 1, 2011, 10:26 PM
Post #14 of 34 (7263 views)
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Re: [trigger] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

All I noticed by adding length to my risers was more range on rears and toggles. With an easier chance of stalling on rears.

I noticed nothing with regard to my dive or recovery arc or flight characteristics of my canopy.


trigger  (D 101390)

Nov 3, 2011, 7:07 AM
Post #15 of 34 (7096 views)
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Re: [hparrish] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

Hi guys,
reading through the replies to this thread here's a list of my thoughts on the subject so far.

1. Increasing /decreasing riser length has no effect on the recovery arc of a given canopy as the planform and trim will remain unchanged.

2. Negliable increase in pendulum effect as the jumpers c of g has moved further away from the canopy.

3. Canopy feels different in flight due to increased toggle range (longer risers) possibly could be rectified by lengthening the brake lines accordingly.

4.Canopy feels twitchier on opening as the canopy is more sensitive to harness input (longer risers + something i have observed also).

5. Increases range when flying with rears, but also increases risk of stall/high speed stall on landing.

6. Obvious but worth a mention. Going too long decreases chance of collapsing/stowing the sliderLaugh.

Please feel free to correct me on any of my thoughts/discuss and add anything the may have been missed/not mentioned as yet T.


DaVinciflies

Nov 3, 2011, 9:49 AM
Post #16 of 34 (7062 views)
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Re: [trigger] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

In reply to:
1. Increasing /decreasing riser length has no effect on the recovery arc of a given canopy as the planform and trim will remain unchanged.

I still disagree with this, as line length is used by canopy designers to affect the recovery arc of a canopy.

Check out post #21 in this thread:http://www.dropzone.com/...covery%20arc;#612543

Quote:
The principles in the following examples are true regardless of canopy size and pilot size. They just may not be as noticable with certain combinations of wingloading.

The LONGER the distance between that imaginary point in your body where the risers would meet if they continued down from the attachment points to the bottom of the canopy, the longer the recovery arc (the amount of altitude required to swing the pilot back under the canopy after a dive).

Take it to an extreme: Imagine having 50 ft. lines on your canopy. It will take much longer for you to swing back under your canopy from a dive with the ludicrous-long lines. On the other end of the spectrum, imagine having 3 foot lines: You would swing back under your canopy very quickly with ridiculously short lines.

Brian Germain lengthened the lines on the Sensei to allow a longer recovery arc specifically for swooping. The Samurai has shorter than normal lines (compared to other canopies in its class) to make it more peppy and agile in turns (more fun).


trigger  (D 101390)

Nov 3, 2011, 10:03 AM
Post #17 of 34 (7055 views)
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Re: [DaVinciflies] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

Were not increasing line length just riser length by maybe 2"
as i said imo this would increase the amount of time it takes to swing back under the canopy i.e pendulum effect but its negliable.
Quote:
Brian Germain lengthened the lines on the Sensei to allow a longer recovery arc specifically for swooping. The Samurai has shorter than normal lines (compared to other canopies in its class) to make it more peppy and agile in turns (more fun).


captain_stan

Nov 3, 2011, 11:16 AM
Post #18 of 34 (7045 views)
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Re: [trigger] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

Quote:
3. Canopy feels different in flight due to increased toggle range (longer risers) possibly could be rectified by lengthening the brake lines accordingly. [my emphasis]

If I may clarify my previous post, this is not something that necessarily begs to be "rectified." If you lengthen the brake lines you negate some of the benefit you might have wanted.

While the toggle stroke is indeed lengthened with longer risers, at some point this can exceed its usable control range. At my W/L with standard 21" risers, the primary range that I use doesn't go any lower than my chest, and I only pull them to the bottom to be sure I've milked all the lift (and drag) out of my canopy as I touch my feet down. I'm guessing that the bottom .5' or 1' of toggle stroke does nothing for me because it's below the stall-point of my canopy. But a person with longer arms might want to feel the usable range in a higher, more-comfortable arm position by lengthening the risers to raise the toggles (and dive loops). Although you can vertically lower the control range by lengthening the lines, you are limited by the riser length in how much you can raise it by shortening the lines. When you reach that limit, longer risers come into play.

OTOH, the total length of stroke might be an issue with a heavy jumper under a big, docile canopy. When we put chubby, short-armed students under big 300-sq-ft F111 canopies, we used some 26" risers so that they would get full-arm extension (up and down) for the control range required to fly and land these monsters. They might not have been able to reach the slider, but all they needed was the toggles anyway. Flare, flare, flare!!!


(This post was edited by captain_stan on Nov 3, 2011, 12:00 PM)


stayhigh  (F 111)

Nov 4, 2011, 8:07 PM
Post #19 of 34 (6892 views)
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Re: [trigger] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

so there is no effect on recovery by changing riser length??
complete bs.
If one can have 50 inch riser does that not change its recovery arc???

and every canopy pilot i know who uses longer riser lengthens their break line accordingly to their own taste so range on toggle theory goes out the door. In fact I like it when I have no input with toggle until toggle is about shoulder level.

it is just matter of feel.
short riser makes me feel like I'm trapped inside the riser and harness vs longer riser with longer chest strap I can freely move my upper body and I can grab risers with full arm extension.


Premier ianmdrennan  (D 25821)
Moderator
Nov 4, 2011, 8:26 PM
Post #20 of 34 (6890 views)
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Re: [stayhigh] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

I feel no difference in recovery arc when going from 21 to 24 inch risers, other than having to re-adjust my brake lines.

Whatever flight change there is, is minimal at best.

I DO like the extra leverage I get, which is why I like the longer risers.

Ian


(This post was edited by ianmdrennan on Nov 4, 2011, 8:26 PM)


craigbey  (C 31991)

Nov 5, 2011, 9:44 AM
Post #21 of 34 (6835 views)
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Re: [ianmdrennan] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

Quote:
21 to 24 inch risers

Just trying to take this a little further...

With the added 3", you're pulling down on the risers 3" more. If you start a HP turn using a double-front technique, you are therefore affecting the trim of the canopy by 3" more.

That should translate into more speed as you start the turn / dive. The steeper trim should affect the speed that you can generate in the turn / dive.

This is meant mostly as a question to those with experience with this technique on longer risers.

Maybe I'm behind the curve, but I just prefer to start with one riser and add the 2nd riser and harness input as needed during the turn. But I could see where the longer risers could provide more potential speed due to the pilot's ability to affect the trim.


Premier ianmdrennan  (D 25821)
Moderator
Nov 5, 2011, 9:49 AM
Post #22 of 34 (6832 views)
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Re: [craigbey] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

Quote:
With the added 3", you're pulling down on the risers 3" more. If you start a HP turn using a double-front technique, you are therefore affecting the trim of the canopy by 3" more.

That should translate into more speed as you start the turn / dive. The steeper trim should affect the speed that you can generate in the turn / dive.


Yes, but what you're describing is the effect of extra leverage (and the reason I like longer risers). Once I let them up though, I find little to no difference.

Basically, I don't (consciously) fly my canopy any differently based on riser lengths.

Blues,
Ian


Pendragon  (D 104102)

Nov 6, 2011, 2:55 PM
Post #23 of 34 (6718 views)
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Re: [craigbey] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

In reply to:
Quote:
21 to 24 inch risers

Just trying to take this a little further...

With the added 3", you're pulling down on the risers 3" more. If you start a HP turn using a double-front technique, you are therefore affecting the trim of the canopy by 3" more.

That should translate into more speed as you start the turn / dive. The steeper trim should affect the speed that you can generate in the turn / dive.

This is meant mostly as a question to those with experience with this technique on longer risers.

Maybe I'm behind the curve, but I just prefer to start with one riser and add the 2nd riser and harness input as needed during the turn. But I could see where the longer risers could provide more potential speed due to the pilot's ability to affect the trim.

The reason for starting on double fronts and letting one up slowly is to achieve the equivalent of a flat turn on toggles; that is a controlled slow turn to start. In essence the ideal is to accelerate the rate of turn as you turn to provide constant force, and not allow the canopy to recover prematurely. I (like many) find this easier to achieve using this technique.

It's harder to start a slow controlled turn using just one riser as it's easy to put too much input in too early.

Given the above, I don't think this has anything to do with trim; rather longer risers just provide the pilot the ability to put more force into the turn, which generates more speed.


P-dro

Nov 7, 2011, 3:31 AM
Post #24 of 34 (6653 views)
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Re: [DaVinciflies] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

In reply to:
In reply to:
1. Increasing /decreasing riser length has no effect on the recovery arc of a given canopy as the planform and trim will remain unchanged.

I still disagree with this, as line length is used by canopy designers to affect the recovery arc of a canopy.
I completely disagree too, I recently changed from 19" to 22", and the difference is recovery arc is clear. I suppose the impact must be different on different canopy, though... I guess the transition between short to long risers must be more noticeable than long to very long too....


(This post was edited by P-dro on Nov 7, 2011, 3:35 AM)


hparrish  (D 25090)

Nov 7, 2011, 9:04 PM
Post #25 of 34 (6537 views)
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Re: [ianmdrennan] Riser length advantages/disadvantages Longer vs shorter [In reply to] Can't Post

+1


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