accuracy

[The111 0]

I'm trying to learn how to be more accurate on my landings, it's always been my weakest point. The past few weekends I've been within a 20m circle or so which is better than I've done in the past, but I want to learn how to land ON A DIME. Or at least in the 4m circle I need to do 25 times for my C license, and at this rate I won't have that level of accuracy at 200 jumps.

I've taken Scott Miller's courses, and I understand the importance of flying a pattern, and that is what has helped me get down to the 20m circle I'm in now. However, and I could be wrong here, I don't think I will ever get in a 4m circle by flying the pattern alone, consistently at least. I start my pattern at 1000ft and that means if I misjudge my altitude by even 30ft and assume a 2:1 glide ratio on final approach, that's 60ft away from my target I will land. Obviously glide ratio varies with wind, but my point is that a 50ft error at 1000ft will cause considerable miss of the target. I think that no matter how good someone is at eyeballing, it's damn near impossible to tell the difference between 950ft and 1000ft (could be wrong again), a "dial" type altimeter is no more accurate, and I am considering buying a Neptune but feel it should not be the deciding factor in me landing where I want to.

So, obviously no matter how good your pattern is, there are going to have to be some small corrections on final. Which brings me to the real point of this post.

On a windy day, I can get damn close to my target since I just setup for a small overshoot and use brakes to bring my landing point back slightly. On my Spectre it doesn't take much wind to allow this to work.

However, on a no wind day, I obviously can't use this trick, and up until now I thought I was confined to landing wherever my pattern puts me (this is what I did yesterday and landed at least 10m away every time). But today I had an idea which makes sense to me, I'm wondering if it's commonly used. On a no wind day, would it make sense to set up for a small undershoot, and then use brakes a bit on final to extend that leg and hit the target more accurately?

Any and all advice is appreciated... I realize with <150 jumps the main thing I need is time/practice/experience, but thinking about it when I'm bored can't hurt either. Another thing that makes it hard to get right on the target - even on a straight in full-glide approach, on a no wind day, my flare causes me to surf a lot (seems like 20-30ft to me, but maybe I'm exaggerating it), so the point I'm actually aiming for on final isn't where I actually touch down... obviously the solution to this is to adjust the point I aim for accordingly.

www.WingsuitPhotos.com

[SkymonkeyONE 3]

You are thinking backwards, Matt. On your final leg, you first do "the accuracy trick" to see where you are going to end up. This assuming you are not sawing your lines and are flying at a certain degree of brake. On "real" accuracy jumps, you turn into final and assume half brakes. From there, you do the accuracy trick. If you, at half brakes, are not going to make it to the target, then you can let up on the brakes to get more glide. If you are still going to overshoot, you can apply a bit more brakes and increase your rate of sink. At 100 feet (under a sport canopy), you let up on the brakes and get full speed back up for your flare. Under larger parachutes you can simply fly in at half brakes and flare the rest of the way to land on target.

[The111 0]

Ah, so at half brakes you have the mobility to change the length of your final leg in *either* direction, i.e. shorten or lengthen. Makes sense, thanks.

www.WingsuitPhotos.com

[DrewEckhardt 0]

The tools you have available under large (I have 244 and 245 seven cells) and small (105 and 120 ellipticals and a 135 square) parachutes are different, although good accuracy is not too difficult under either.

With a smaller parachute, you can try to be a little long on your swoop and either kill your speed + lift by sinking and poping up at the end (fly it all the way into the ground if you're not going to over-shoot and expect to land a bit faster) or curve your swoop if you're going to be really long.

Bigger (this depends on wing loading) parachutes land well even when you start your flare with a lot of brakes applied.

Either way, you can still steepen your glide path on final and return to full flight before landing.

[The111 0]

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Either way, you can still steepen your glide path on final and return to full flight before landing.

This doesn't work on a no-wind day though, right? Which is why I suggested setting up for a small undershoot on a no-wind day and using brakes to flatten your glide path a bit on final, also returning to full flight before landing.

EDIT: Well, I guess you can go steeper than full glide on no wind days, but that would require front riser input as opposed to toggle. Right?

www.WingsuitPhotos.com

[DrewEckhardt 0]

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Either way, you can still steepen your glide path on final and return to full flight before landing.

This doesn't work on a no-wind day though, right? Which is why I suggested setting up for a small undershoot on a no-wind day and using brakes to flatten your glide path a bit on final, also returning to full flight before landing.

EDIT: Well, I guess you can go steeper than full glide on no wind days, but that would require front riser input as opposed to toggle. Right?

Wrong.

Brakes work fine with no wind or even a slight tail wind, although you only experience the canopy's change in glide ratio while wind makes your approach path change with any difference in the forward component of your velocity.

Without too much of a tail wind, pulling the brakes down to just short of stalling will give you the steepest glide you can have without increased airspeed.

Decreasing the brake application will make this less pronounced until you're matching your full-flight glide ratio. Try flying anything other than a square seven cell next to people at various wing loadings and you'll find that there's a huge range where you match.

Go farther up and the glide will be flatter than full flight. With many canopies (At least the PD Sabre, Stiletto, and Spectre), the flattest glide is obtained with a little brakes (flatter than you can get with rear risers).

[The111 0]

I realize it's a bad habit to simply quote someone else's word as gospel, but in Scott Miller's canopy course, he said in a no wind day, 1/4 brakes is flatter glide than full flight, 1/2 brakes is flatter than 1/4, and 3/4 is flatter than 1/2. I am aware that there is a point where your brakes actually do cause you to sink in no wind conditions, but if this point is really past 3/4 brakes, wouldn't it be very close to the stall point? I know that on final approach I don't feel comfortable in any deeper than 1/2 brakes. I don't want to risk a stall at 100 feet.

But you know, I kind of wonder about this, since several weeks ago I had a bad spot on a no wind day, and rather than use the accuracy trick and watch what the brakes did, I simply applied half brakes and aimed at the DZ. I wasn't too worried since I was over a clear field, but I really felt like I sunk straight down. I guess what I need to do is use the accuracy trick to figure out exactly how my own canopy responds to inputs.
The bottom line is I don't like going past moderate brakes on final, and if it takes deep brakes to sink you in no wind, I'd rather shoot for an undershoot, then use light brakes to glide all the way to the target. Make sense?

www.WingsuitPhotos.com

[quade 3]

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I realize it's a bad habit to simply quote someone else's word as gospel, but in Scott Miller's canopy course, he said in a no wind day, 1/4 brakes is flatter glide than full flight, 1/2 brakes is flatter than 1/4, and 3/4 is flatter than 1/2.

Without ever reading Scott Miller's text or hearing his words to you I believe it's possible that one of several things may have given you the wrong impression: his wording, your understanding, the use of inexact terms or your understanding of them . . .

For every canopy, configuration and wing loading there is one and only one Angle of Attack which will give the highest lift/drag ratio and therefore the best glide ratio (longest glide in no wind) and settling into static stability of the best glide airspeed (Vg).

Your canopy actually has two basic different configurations: using front and rear risers alone or using toggles. In an airplane, this would be roughly analogous to flying with and without flaps.

The "flattest" glide (highest lift/drag) might be with rear risers alone or might be a bit of toggles. It would depend on the exact canopy and wingloading.

There is yet another AoA and airspeed to consider which is known as Minimum Sink Airspeed. This would be the AoA / airspeed you'd want to glide if your purpose was to stay aloft for the longest period of time. In still air, you wouldn't fly as -far-, but you would stay aloft longer.

It's possible that there has been a bit of confusion over the definitions and usage of the two.

When gliding -with- the wind you might get considerably further over the surface of the ground by using the Minimum Sink Airspeed.

When gliding -into- the wind you might do slightly better over the surface of the earth by increasing your airspeed above Vg. Since most canopies are already trimmed a bit faster than Vg, you'd need to experiment a bit at the time to see if you were in fact helping or hurting things. Increasing your airspeed by anything more than 1/2 the wind speed will probably not be productive. In a 20 knot wind, you'd probably have to hold your front risers to increase that airspeed by 10 knots. To do that for a couple of minutes is probably going to be very tiring.

quade -
The World's Most Boring Skydiver

[The111 0]

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For every canopy, configuration and wing loading there is one and only one Angle of Attack which will give the highest lift/drag ratio and therefore the best glide ratio (longest glide in no wind) and settling into static stability of the best glide airspeed (Vg).

I understand that. What Scott taught in the class, and I haven't got a chance to thoroughly verify experimentally, is from "full glide" (toggles up all the way), your glide angle gets progressively flatter as you apply more and more brakes, even as far as 3/4 brakes. If this is true, and and the ideal glide angle (from toggle input alone) is close to 3/4 brakes, that means to steepen your glide angle below "full glide" on a no wind day, using only toggles, you'd have to go past 3/4 brakes and dangerously close to the stall point. Right?

www.WingsuitPhotos.com

[quade 3]

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What Scott taught in the class, and I haven't got a chance to thoroughly verify experimentally, is from "full glide" (toggles up all the way), your glide angle gets progressively flatter as you apply more and more brakes, even as far as 3/4 brakes.

Without doing any experiments on your canopy and wingloading I'm going to go out on a limb and state that it's probably -not- true. Again, it's possible that either he is in error in his teaching, or that you are in error of your understanding of what he actually said.

My -guess- is that your best glide ratio using your toggles (your profile lists a Spectre loaded at about 1.1:1 and I'm almost certain you'll find this to be the case.) is going to be about 1/8 to 1/4 of the toggle stroke also dependant on your riser and arm length.

quade -
The World's Most Boring Skydiver

[The111 0]

Thanks for the replies, Quade.

I am positive I didn't misunderstand Scott, but I am inclined to think your answer applies to my situation more... the one time I had a long spot in no wind, I simply applied 1/2 to 3/4 brakes and flew toward the target. I neglected to try different control inputs and see which worked better, but I am almost sure that my canopy would have made it much, much further with no brake input at all; with the amount of brakes I had on I barely seemed to make any forward progress.

Another quick hypothetical... I do plan on testing all this stuff out but sometimes I'm not so good at the accuracy trick and never seem to have as long to do it as I want to, so I like to think about this stuff ahead of time. I notice you're on a Spectre loaded slightly higher than me, so your experience is probably at least somewhat close to mine. If we designate "full glide" (toggles up) as 0, and stall point 1, then you are saying max flattest glide angle in no wind, toggles only, is at about 0.125 to 0.25. Here is my question: how far do you have to go to get a glide which is steeper than full glide (0)? I'm guessing it's around 0.5 (half brakes)... the thing is, as I've said earlier, I don't like to really go past half brakes on final approach, which brings me back to my original question: can you safely steepen your glide angle on final approach, on a no wind day, using toggles, without getting too close to the stall point? Or is it better to set up for a small undershoot and use slight brake input to extend your trajectory to get you right on target?

www.WingsuitPhotos.com

[quade 3]

Again, we're already confusing the terms "full glide" with "best glide".

-ANY- other toggle position other than "best glide" (for the sake of this discussion and this discussion ONLY let's call it 1/4 brakes) is steeper than "best glide".

With the toggles all the way up, you will be moving faster.
With the toggles further than 1/4 brakes you will be moving slower.

In -both- cases you'll be flying a shorter distance and therefore a steeper angle than if you had the toggles at 1/4 brakes.

Without doing a whole lot of testing I can't make a perfect chart of what would happen with your canopy, but I can draw you a sort of generic chart of a mythical "Ghost 170" canopy.

If you look at the chart, called a polar curve, you'll see how this canopy behaves during glides. This particular polar curve I've provided is ONLY for illustration pursposes and does NOT reflect the actual performance of any particular canopy. It's just to give you an idea of how things work.

Notice that with the toggle full UP, it's flying faster than best glide. In order for it to fly even faster, you need to pull down on the front risers. Doing so will make the canopy fly faster and decend quicker.

Adding more toggle input slows the canopy down to best glide airspeed. Adding even more toggle slows it down further to minimum sink speed and if you continue to add toggle input, you'll eventually slow down to stall speed. Below stall speed the canopy is no longer "flying" -- it's only a drag device.

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which brings me back to my original question: can you safely steepen your glide angle on final approach, on a no wind day, using toggles, without getting too close to the stall point? Or is it better to set up for a small undershoot and use slight brake input to extend your trajectory to get you right on target?

Try to fly your pattern and final so that you make as few adjustments as possible.

In a no wind situation, I find that setting up my aim point slightly short of my actual target and then using light brakes to extend the glide slightly for the round out and flair works better and causes fewer injuries than trying to sink in with deep brakes.

Until you're fairly experienced, I would not recommend trying to stretch the glide using rear risers. This can give you slightly greater range, but close to the ground can cause a lot more problems.

quade -
The World's Most Boring Skydiver

[johnny1488 1]

Just to defend Matt's ears, Scott does teach that deep brakes will provide the best glide on a canopy. He spoke from experience on PD canopies and said most others should be the same. I told him I was going against the grain with my xfire and he agreed as he has heard many an Icarus jumper say they find rear risers to produce best glide. Scotts analogy IIRC has only pertaining to no and tailwind conditions, but he said minimizing the rate of descent would always (his words) produce the best glide.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[The111 0]

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Again, we're already confusing the terms "full glide" with "best glide".

Actually, I understood what you meant entirely, which is why every time I used the phrase "full glide", I added the parenthetical (toggles up). I realize that's not "best glide", but "full glide" is a commonly used phrase to describe no toggle input.

I think maybe the worst descriptor I used is "max glide" at one point in my previous post, so I went back and edited that to say flattest glide. Any time I am describing the angle of glide I used descriptors flat or steep. The only time I use the phrase "full glide" is to describe no toggle input as it's commonly used.

I understand that flattest glide is at a certain small input and that "full glide" is a bit steeper, and that there is a slow speed past the flattest glide which creates the same glide angle as "full glide". I am curious how close you have to get to a stall to go even steeper.

Would you say, on a no wind day, using toggle input only, you have to get dangerously close to your stall point to make a steeper glide angle than "full glide" (toggles up)?

www.WingsuitPhotos.com

[The111 0]

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Scotts analogy IIRC has only pertaining to no and tailwind conditions, but he said minimizing the rate of descent would always (his words) produce the best glide.

That's exactly how he explained it, and I definitely agree that with a strong tailwind that is true. But when jumping in no winds it did seem to me like half to deep brakes didn't help my glide as I expected.

Pertaining to no wind, he did admit there was a point of diminishing return, where you decreased your vertical speed so much that your glide angle would start steepening again, but he said it should be past 3/4 brakes on most canopies. He seemed very certain that 1/2 and even 3/4 brakes would make you glide flatter in no wind conditions.

www.WingsuitPhotos.com

[The111 0]

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Try to fly your pattern and final so that you make as few adjustments as possible.

Agreed. But as I pointed out originally I am always a little off so I like to bias that little bit in a direction which is able to fine-tuned on final.

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In a no wind situation, I find that setting up my aim point slightly short of my actual target and then using light brakes to extend the glide slightly for the round out and flair works better and causes fewer injuries than trying to sink in with deep brakes.

That's kind of what I was thinking. And I wouldn't try using rear risers at this point anyway.

www.WingsuitPhotos.com

[quade 3]

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Would you say, on a no wind day, using toggle input only, you have to get dangerously close to your stall point to make a steeper glide angle than "full glide" (toggles up)?

Again, this will depend on a number of factors: canopy, wingloading, riser and arm length and gust conditions among them.

Generally speaking, I don't think you have to get "dangerously close" to a stall in order to take advantage of a lot of sink in some canopies. In particular, the Spectre has excellent performance and stability in very, very deep brakes and on my set up that would be from say, waist deep to -almost- full arm extention.

On other canopies, that would be a -serious- mistake.

quade -
The World's Most Boring Skydiver

[kallend 1,625]

I think this is VERY canopy specific. In still air (ha ha) my Stiletto seems to get a flatter and flatter glide as I go to 3/4 brakes. It only seems to steepen when on the verge of stalling, and I certainly wouldn't want to try sinking it in that close to the stall point. I don't recall Sabres doing this (long time since I jumped one). I recall sinking a Sabre in without much trouble.

I got a nice little booklet from the Soaring Society of America (SSA) that has excellent explanations of best glide, minimum sink, effect of winds etc.

Now, if we just had some real L/D data for canopies, we could settle these debates once and for all.

...

The only sure way to survive a canopy collision is not to have one.

[The111 0]

Yes, this is how Scott said all the popular PD "S" canopies are (Spec/Sab/Stil). On the next no wind day I find where I actually have enough time under canopy to apply each brake condition and observe what it does to my trajectory, I will try to find out for sure how my Spectre performs...

Obviously, even two of the "same" canopies could perform differently due to a variety of conditions...

www.WingsuitPhotos.com

[quade 3]

I was going to do a series of flights last season to generate polar curves for my Spectre, but never got around to it (4-way training, et al). Right now it's way too freekin' cold at altitude to even contemplate it and I'll have to wait until at least next spring.

quade -
The World's Most Boring Skydiver

[The111 0]

How do you plan on actually gathering the data? Just by eyeballing and using the accuracy trick? Or using GPS or something? (I am really not familiar with GPS at all...)

www.WingsuitPhotos.com

[skygod7777 0]

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Right now it's way too freekin' cold at altitude to even contemplate it and I'll have to wait until at least next spring.

now i know this is way off topic, but you live in cali right? and it's too cold for you to jump, dude i don't even want to hear it. it's like 20 degrees right now, and the high is a heat wave now 28

lata

[DrewEckhardt 0]

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I am aware that there is a point where your brakes actually do cause you to sink in no wind conditions, but if this point is really past 3/4 brakes, wouldn't it be very close to the stall point? I know that on final approach I don't feel comfortable in any deeper than 1/2 brakes. I don't want to risk a stall at 100 feet.

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I've yet to fly a canopy which stalls unpredictably when given gentle control inputs. Flown that way in no wind conditions, before a parachute stalls completely it'll rock back a bit, you'll slow down perceptably, and have plenty of time before anything nasty happens to lift the toggles a little.

Obviously you want to do this high enough that you're in front of the canopy on landing and have time to be flying fast enough to get a comfortable flare, although "high enough" includes a significant portion of final approach.

I've gotten a bit too deep on an accuracy approach with both my big seven cells and Samurai 105 - both weren't big deals.

Obviously, this is something to play with up high and before you need it. It probably isn't a good idea in gusty wind conditions either, although there more moderate brake applications will bring you down steeper.

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[quade 3]

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now i know this is way off topic, but you live in cali right? and it's too cold for you to jump, dude i don't even want to hear it. it's like 20 degrees right now, and the high is a heat wave now 28

I didn't say it was too cold to jump, I said it was too cold to do testing.

Last weekend we had ice on the ground, at least during the early morning. I suspect we may have similar temps this weekend.

Testing of this kind would require multiple deployments at CRW type altitudes. Currently it's butt cold up there and while I'm willing to hang out for a moment or two on exit, there just ain't no way you're getting me to to do a deployment and float around gathering data.

The data would be gathered using a a Kestral 4000.

quade -
The World's Most Boring Skydiver

[rigging65 0]

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now i know this is way off topic, but you live in cali right? and it's too cold for you to jump, dude i don't even want to hear it. it's like 20 degrees right now, and the high is a heat wave now 28

Yeah, 'cause you know, everywhere in California is always 70 degrees and sunny...oh, and we all surf to work...and hang out with movie stars at coffee houses, too...sheesh...

"...and once you had tasted flight, you will walk the earth with your eyes turned skyward.
For there you have been, and there you long to return..."