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Question about coming back from a long spot

 

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dthames  (B 37674)

Dec 7, 2012, 10:30 AM
Post #26 of 72 (1969 views)
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Re: [Deimian] Question about coming back from a long spot [In reply to] Can't Post

The USPA Canopy Control Proficiency Card has a jump where you return from a long spot. I was instructed to take the spot about 1 mile beyond what was normal, to open at normal altitude (inflated about 3,000), and then work with the brakes and the risers to figure out the best way to make it back.

I tried hanging on the brakes for a while and determined how much good that did me. Then I got on the rear risers and tried to see how they would work. I stayed with the rear risers until I got back to the edge of the field, just under 1000 feet. I learned a lot and it was a great challenge.

I got a chuckle out of it because I was told that some of the jumpers that didnt know what I was up to saw me low and far away. Someone remarked about the bad spotand then I made it back thanks to my poofy Pilot and a bit of a tail wind.


DocPop  (C License)

Dec 7, 2012, 10:43 AM
Post #27 of 72 (1959 views)
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Re: [klippetop] Question about coming back from a long spot [In reply to] Can't Post

In reply to:

Hypothetically, if windspeed is faster than canopy speed (so youre feeling the relative wind on your back). Wouldnt you want to make yourself big? I know that this is more rare than you going faster than the wind.

This won't happen. To feel the relative wind on your back, you would have to be flying backwards. Forget about windspeed (which is measured relative to the ground) - your canopy is designed to fly with forward airspeed which is how it stays inflated and creates lift.

ETA: I saw that you subsequently worked this out yourself. Good stuff! This is important knowledge to have - and not everyone does!


(This post was edited by DocPop on Dec 7, 2012, 10:46 AM)


wolfriverjoe  (A 50013)

Dec 7, 2012, 10:50 AM
Post #28 of 72 (1948 views)
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Re: [airtwardo] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
THAT being said, nothing wrong with heading for a road when you see you won't make it back...it makes it easrier for someone at the DZ to snag you when you land, it keeps you off farmer Mcnastys crops, cows & meth lab...and though as you said there may be power-lines etc to be wary of 'other than that' - the area next to most roads are relative free of obstacles.

Wow. It's pretty rare that I disagree with you, but I certainly do here.

Roads usually have powerlines, ditches, fences, mailboxes, culverts (driveways that go over the ditch), not to mention cars. They are a bad place to try and land anywhere near (the cars and especially big trucks push a lot of air when they go past, nasty turbulence).

I was taught to avoid any straight lines. Field edges, road sides, even boundaries between two fields. They often have the above mentioned obstacles.

The ideal off landing area is a hayfield or empty pasture. Right in the middle.
Uncultivated fields are also good, but beware the furrows, I've known ankles to be broken landing in a plowed field.

Cultivated fields aren't the best. The farmers tend to get annoyed when their livelyhood gets damaged (we used to have a "field fund" - out landers tossed a buck in each time, the money was given to the farmer at the end of the year). And landing in crops has it's hazards. Beans grab ankles, wheat can make height judgement difficult and corn...

Hurts.

Occupied pastures are bad news too. Aside from "landmines", you don't know the temperament of the "occupants." Horses tend to spook, cows tend to be curious, and if it's a big open field with only one occupant, don't land there (think about why he's alone and that it might be because he doesn't get along with others well).

It's not that hard to pick good "out landing" areas. In a 182 there's plenty of time to look around and see what's open, and what's in it. Spotting the different types of fields from the air takes a bit of practice, but anyone who's jumped for a while can help pick stuff out. Or you can try to guess what's in each field near a road, and then go see if you were right.


airtwardo  (D License)

Dec 7, 2012, 11:18 AM
Post #29 of 72 (1936 views)
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Re: [wolfriverjoe] Question about coming back from a long spot [In reply to] Can't Post

The ideal off landing area is a hayfield or empty pasture. Right in the middle.
Uncultivated fields are also good, but beware the furrows, I've known ankles to be broken landing in a plowed field.

In reply to:

Indeed it is, I guess I should have made that point clearer instead of just saying a 'clean' area...

As far as roads & straight lines...sure there is some logic to that, one needs to be aware of what to look for and hopefully you're facing into the wind on landing and can select an open spot that may be 'along those lines' so to speak.

Keep in mind the 'avoid straight lines' doctrine is a hold-over from the round parachute days which of course had a lot less control & accuracy...yes it still has some validity but not as much as in days gone by. Again that 'circle of safety' needed was a LOT bigger then.

Going full bore downwind with the idea of hooking a 180 into the wind at the last possible second in order to save some steps walkin' back is a really poor approach.

Understand you're in a bad 'unusual' situation and plan a normal pattern accordingly...if you are at say 500' facing into the wind and can't see & avoid power-lines or fence-lines ~ Darwin kinda wins!

It's a judgement call I guess, one needs to be realistic about their canopy control abilities and accuracy skills.

You're not landing a fighter at 200 kts, your circle of safety regarding the place & amount of clear area you need should be well established in your mind while on downwind...if you 'need' a football field to feel comfortable, by all means head to the planted field...if you know you can land standing up between parked cars in a Waly-mart parking lot (cough cough) it opens up the possible safe zone quite a bit.

High trees & water scare me more than power lines...the lines usually are 'avoidable' with steering input on base & final...not always the case with trees & water if they cover a big enough area.

It's situational specific obviously, another reason to try to be aware of your surroundings...a highway vs. a farmers field access road have significant differences regarding possible obstacles.

If you can't see & avoid a mailbox or light pole, a with a square parachute from 200'...ummm, ya should really get to working on either that or how to pick up a 7-10 split for a spare!
Sly


(This post was edited by airtwardo on Dec 7, 2012, 11:49 AM)


klippetop  (C 2629)

Dec 7, 2012, 11:45 AM
Post #30 of 72 (1915 views)
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Re: [wolfriverjoe] Question about coming back from a long spot [In reply to] Can't Post

Thx for the feedback. I'm pretty sure, i'm not the only rookie who could learn something from this thread. But I like learning the mechanichs of canopy flight..


pchapman  (D 1014)

Dec 7, 2012, 12:12 PM
Post #31 of 72 (1903 views)
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Re: [wolfriverjoe] Question about coming back from a long spot [In reply to] Can't Post

[EDIT: Looks like Twardo has made the point already but anyway:]

There is actually a happy medium in the debate on "go for a road" vs. "go for a field":

I say, go for near a road, but not right next to it, and only to the limitation of your own skill.

Some people make a beeline back towards the DZ and when they can't make it, end up in the middle of some muddy or crop filled field. Better to make the decision early and head for someplace safe but easier to get home from on the ground, like near an access road.

If you don't want to deal with gravel or pavement on roads, telephone and power wires, ditches, fences, etc, then land a short ways into the neighbouring field -- 50 m, 100m, whatever is in your comfort zone based on the conditions.

Personally I've swooped under a wire stretched across a road and then run the landing off into a ditch at dusk, so as not to spook an oncoming car too much -- but that doesn't mean that's the normal smart thing to do...

So "go for a road" should be interpreted as "near a road but a safe distance away from related obstacles".

(And wolfriver, thanks for countering the "wind at one's back" misconception!)


(This post was edited by pchapman on Dec 7, 2012, 12:14 PM)


linebckr83  (D 30571)

Dec 7, 2012, 12:12 PM
Post #32 of 72 (1902 views)
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Re: [klippetop] Question about coming back from a long spot [In reply to] Can't Post

This is the way it was described to me:

Imagine that you are in a giant blimp. So giant that you can fly a parachute inside of it. Say this blimp is moving forward at 100mph. Inside of it, you are flying your parachute around with a forward speed of 20mph.

If you are flying your canopy in the same direction as the blimp is flying, does your canopy "see" 120mph of air or only 20? If you turn around and fly the opposite direction, will you feel 80mph of wind on your back? The answer of course is no.

The blimp represents an air mass. Wind is simply a measure of the motion of this air mass in relation to the ground. So if you are flying your canopy in wind, you are flying around inside of this moving air mass just like the blimp example. The only affect it will have is in relation to the ground. Your parachute will "see" the same speed of air moving over it regardless of how the air mass is moving.

So if you are upwind on a long spot, you are in an air mass moving towards your target, and you want to stay off the ground until you get to this target. Like others said, generally your best bet is to ride in deep brakes and essentially "float" and let the air mass carry you to your target.

If you are downwind on a long spot, you are in an air mass moving away from your target. Obviously in this case you do not want to simply "float" as the air mass will just carry you further away. You need as much forward speed as possible to overcome the air mass's opposite motion and get to your target. Your best bet is to get in full flight and possibly use front risers, but people tend to debate on that part.

In either case, you want to move forward in the air mass as much as possible. How do you go forward more? You speed up. How do you speed up? You get rid of what is slowing you down (reduce drag). The best way to do this is get small. Pull legs up, tuck arms in. Your drag is reduced and your forward speed increases. This helps in either case, whether you're floating in the air mass or fighting it.

Many people think if they are upwind they can "get big" and use the wind to push them back. But refer back to the blimp example. If the same blimp is flying 100mph forward, and you are inside it flying 20mph normally, you have 120mph speed in relation to the ground. Say you get as big as possible. What changed? You just increased your drag, and your canopy speed reduces to 18mph. Now you are traveling at 118mph. You are hurting your chance at getting back. If you get small and begin flying at 22mph, your speed over the ground is now 122mph.

So remember...the wind is what it is. It's a moving air mass and you have no control over that. What you can control is your own speed while in this air mass, and amount of time inside it.

For the future in case you don't know the difference between groundspeed and airspeed. In the blimp example, your airspeed is 20mph. It is the physical flow over and around your airfoil. Your ground speed would be 120mph, and it is your speed in relation to the ground. So basically a sum of all things affecting your speed over the ground. Very different things and its an important concept to understand in regards to flying canopies.


Premier billvon  (D 16479)
Moderator
Dec 7, 2012, 12:51 PM
Post #33 of 72 (1887 views)
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Re: [Deimian] Question about coming back from a long spot [In reply to] Can't Post

Some tricks:

1) Get your drag as low as possible. Take off booties or keep them oriented into the wind. Unzip wingsuits as much as possible. Take off swoop cords if so equipped. Kill slider and bring it down if possible.

2) Let the canopy spread out. Loosen your chest strap if safe to do so and get the slider down as low as possible.

3) Try spreading your rear risers to improve your glide ratio a bit. It flattens your canopy a little and pulls the center of the tail down a little.

4) Flying into the wind the above tricks work pretty well. Flying downwind going to brakes works well. The trick is to stay in the air as long as possible so the wind helps you for as long as possible. Keeping brakes stowed might be an option. NOTE - if you do this make sure you unstow them before you get to your decision altitude, so if you discover a stuck/broken brake line you can deal with it.

5) In no wind you can experiment with brakes. For most canopies, a little bit of brake gives you a better glide than using rear risers.


Quagmirian  (A 110392)

Dec 7, 2012, 1:02 PM
Post #34 of 72 (1876 views)
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Re: [billvon] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
For most canopies, a little bit of brake gives you a better glide than using rear risers.
Does this actually improve absolute glide ratio, ie would you cover more ground in still air?


airtwardo  (D License)

Dec 7, 2012, 1:36 PM
Post #35 of 72 (1862 views)
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Re: [Quagmirian] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
In reply to:
For most canopies, a little bit of brake gives you a better glide than using rear risers.
Does this actually improve absolute glide ratio, ie would you cover more ground in still air?

It's hard to say it absolutely will with all canopies, it's dependent on the wing and the loading etc. It usually does...when ya find the sweet spot & you are in the air longer with a minimal loss of forward speed you go father.

It's that you're trading more time under canopy for forward speed...with a tailwind you tend to cover a lot more ground that way, not always necessarily so in 'still' air depending on the trim etc.


(This post was edited by airtwardo on Dec 7, 2012, 1:55 PM)


DocPop  (C License)

Dec 7, 2012, 1:57 PM
Post #36 of 72 (1858 views)
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Re: [Quagmirian] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
In reply to:
For most canopies, a little bit of brake gives you a better glide than using rear risers.
Does this actually improve absolute glide ratio, ie would you cover more ground in still air?

I am not so sure about that. Brakes add drag, using a touch of rears will improve the glide path without adding to the drag.

Of course this may be offset by the fact that holding rears for a long time is hard work.


labrys  (D 29848)

Dec 7, 2012, 2:02 PM
Post #37 of 72 (1855 views)
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Re: [DocPop] Question about coming back from a long spot [In reply to] Can't Post

Quote:
This is not realistic. The relative wind under canopy is always from the front (unless your feet are on the ground).

I can't tell if you're joking or not Crazy


airtwardo  (D License)

Dec 7, 2012, 2:13 PM
Post #38 of 72 (1847 views)
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Re: [labrys] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
Quote:
This is not realistic. The relative wind under canopy is always from the front (unless your feet are on the ground).

I can't tell if you're joking or not Crazy


In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil.

It is opposite to the direction of movement of the aircraft or airfoil relative to the atmosphere.


Premier billvon  (D 16479)
Moderator
Dec 7, 2012, 2:15 PM
Post #39 of 72 (1846 views)
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Re: [Quagmirian] Question about coming back from a long spot [In reply to] Can't Post

>Does this actually improve absolute glide ratio, ie would you cover more ground in still air?

In general, yes. Per Brian Germain, brakes are almost always a better option than rear risers, since rear risers deform the canopy and cause a lot of drag.


Premier billvon  (D 16479)
Moderator
Dec 7, 2012, 2:18 PM
Post #40 of 72 (1843 views)
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Re: [DocPop] Question about coming back from a long spot [In reply to] Can't Post

>I am not so sure about that. Brakes add drag, using a touch of rears will improve
>the glide path without adding to the drag.

Pulling down part of the tail does indeed add some drag. Distorting the entire canopy with rear risers adds more drag.


labrys  (D 29848)

Dec 7, 2012, 2:33 PM
Post #41 of 72 (1841 views)
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Re: [airtwardo] Question about coming back from a long spot [In reply to] Can't Post

Quote:
In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil.

I do get that... but there's a difference between the direction of movement of the atmosphere relative to an airfoil and the influence that the actual direction of the wind have on the ground speed of that airfoil.


airtwardo  (D License)

Dec 7, 2012, 2:48 PM
Post #42 of 72 (1834 views)
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Re: [labrys] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
Quote:
In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil.

I do get that... but there's a difference between the direction of movement of the atmosphere relative to an airfoil and the influence that the actual direction of the wind have on the ground speed of that airfoil.

Of course, but in the context DocPop was using it I think he's accurate. IIRC a poster he was answering asked about relative wind at his back...strictly speaking if that happens, you've put the canopy on the harness wrong.
Wink


DocPop  (C License)

Dec 7, 2012, 4:42 PM
Post #43 of 72 (1803 views)
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Re: [labrys] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
Quote:
In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil.

I do get that... but there's a difference between the direction of movement of the atmosphere relative to an airfoil and the influence that the actual direction of the wind have on the ground speed of that airfoil.

Relative wind and groundspeed are totally independent concepts.

In an uncoordinated turn when the canopy is "skidding" sideways the relative wind may be coming slightly from one side but otherwise it is from the front and slightly down (as evidenced by the fact that the pilot chute trails directly behind the wing).


DocPop  (C License)

Dec 7, 2012, 4:44 PM
Post #44 of 72 (1800 views)
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Re: [billvon] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
>I am not so sure about that. Brakes add drag, using a touch of rears will improve
>the glide path without adding to the drag.

Pulling down part of the tail does indeed add some drag. Distorting the entire canopy with rear risers adds more drag.

Now that I must take issue with.

If that were the case then why would swoopers use rears to maximize their glide ("swoop") and only switch to toggles when the airspeed drops to a point where extra lift (with its attendant drag increase) is needed?

To be clear, in the long spot scenario, I am talking about a "touch" of rears, not a full plane-out.


(This post was edited by DocPop on Dec 7, 2012, 4:47 PM)


Tuna-Salad  (C 38765)

Dec 7, 2012, 6:48 PM
Post #45 of 72 (1778 views)
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Re: [Deimian] Question about coming back from a long spot [In reply to] Can't Post

My $0.02 if you are on a long spot immediately start looking for and select an alternate landing area. People get hurt when they "think" they can make it back but are not sure then end up being unprepared.


davelepka  (D 21448)

Dec 7, 2012, 7:01 PM
Post #46 of 72 (1775 views)
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Re: [StreetScooby] Question about coming back from a long spot [In reply to] Can't Post

Quote:
Keep in mind when picking a off-DZ spot to land - there are power lines next to most roads, and you might not see them until you're low. Also, when landing in fields, keep an eye out for barbed wire fences. They're very difficult to see until you're right on them,

This is the reason to use a landing pattern when landing off. It provides two major functions for off-field landings, the first one is that the downwind leg gives a great chance to 'sweep' the field at a low-ish altitude for obstacles.

As you fly the downwind leg, you're going right past your intended touchdown point at something less than 1000ft. This gives you an excellent vatage point to spot some obstacles which may have not been obvious from higher up. Gopher holes, fences, logs, etc, whatever it is, you stand the best chance of spotting it when down low.

The second advantage comes into play if you do spot an obstacle. You can use your accuracy skills to alter your turn points for your base and final legs to make sure that you end up clear of said obstacle.

The other obvious advantage of using a pattern is that it will reduce the possibility of making a low turn. If you use a pattern when landing at the DZ, and don't make low turns there, repeat that skill when landing off and it will increase your chances for success.

The thing about landing patterns and accuracy is that they seem fairly mundane and 'common-place' after so many jumps at the DZ. When everything is going well, it starts to feel like driving through an empty parking lot but still staying in between the lines. Pointless and time-consuming.

However, there is a point to those skills and developing them to a sharp point. Landing off is one of them, sudden changes in wind speed or direction is another, and traffic or other incursions would be a thrid. All fairly rare events, but when they do happen, you're going to be gald you have the skills to remain in control of the situation and make the right moves.


kallend  (D 23151)

Dec 7, 2012, 7:54 PM
Post #47 of 72 (1766 views)
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Re: [klippetop] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
I've been taught, that in my big ass student canopy, when I give myself a bad spot and risk going backwards because of headwind, it's better to be at a 45 degree angle to the wind. The theory should be, that I present less canopy to the wind and by zigzagging with flat turns, I can cover more ground.

I havent done it enough times to know if it's actually working yet. Any comments from the canopy gurus? Do i burn too much altitude on the turns?

.

Bad advice. The guy probably believes in the "45 degree rule" too.


kallend  (D 23151)

Dec 7, 2012, 8:00 PM
Post #48 of 72 (1763 views)
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Re: [DocPop] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
In reply to:
In reply to:
For most canopies, a little bit of brake gives you a better glide than using rear risers.
Does this actually improve absolute glide ratio, ie would you cover more ground in still air?

I am not so sure about that. Brakes add drag, using a touch of rears will improve the glide path without adding to the drag.

Of course this may be offset by the fact that holding rears for a long time is hard work.

According to John LeBlanc of PD (but what does he know???) it is very canopy dependent whether brakes or rear risers has the better result.


wolfriverjoe  (A 50013)

Dec 7, 2012, 8:02 PM
Post #49 of 72 (1762 views)
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Re: [pchapman & 'Twardo] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
...There is actually a happy medium in the debate on "go for a road" vs. "go for a field":

I say, go for near a road, but not right next to it, and only to the limitation of your own skill...

That's true. I tend to be extra conservative under unusual circumstances. If the situation is not normal, I like an extra margin for error, because I know errors are more likely.

And I learned "emergency landing" concepts in a plane a long time (longer than I care to admit) before I ever even saw a sport parachute.
The power lines and fences tend to be harder to see in time from an airplane than under canopy, and last second changes in plan are a lot easier under canopy.

So maybe the "middle of a huge field" is an over-reaction, or continuing on from what I was taught in my FJC. Or maybe a little lack of confidence in my accuracy under odd circumstaces.


DocPop  (C License)

Dec 7, 2012, 8:36 PM
Post #50 of 72 (1753 views)
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Re: [kallend] Question about coming back from a long spot [In reply to] Can't Post

In reply to:
In reply to:
In reply to:
In reply to:
For most canopies, a little bit of brake gives you a better glide than using rear risers.
Does this actually improve absolute glide ratio, ie would you cover more ground in still air?

I am not so sure about that. Brakes add drag, using a touch of rears will improve the glide path without adding to the drag.

Of course this may be offset by the fact that holding rears for a long time is hard work.

According to John LeBlanc of PD (but what does he know???) it is very canopy dependent whether brakes or rear risers has the better result.

Did he say that in still air?

What exactly was the context?


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