Forums: Skydiving: Gear and Rigging:
My little project

 

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RiggerLee

Jul 25, 2012, 8:12 AM
Post #26 of 272 (4854 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

I'm not sure exactly how you're going about this. Are you a para glider pilot? Ever done any towing? It's actually a bit more complicated then it seems and it can all go fine and you think that every things cool til it's not. You don't hard point some one to the vehical. There's a wench or more like a spool. It's not just that they're trying to feed out more line so that they can get hight it's a safty thing. The canopy wants to fly at a certin glide angle. But it's just as happy 90 deg to the side as it is above. You can get into some thing called "Lock Out" Basicly it happens when you get too far to the side for what ever reason. Cross wind, collapsed cell, inatension doesn't matter. The rope beguins to pull you out from under the canopy and it can excead the athorith of your control input. At that point it bitch slaps you into the ground. Bad scene. The only way to recover is to lower the tension on the rope. Let the pilots body swing back under the canopy so that he can turn in and get more back on to center. That's what the wench, or more accerately the spool with the break is for. The driver can not react fast enough. Don't be stupid. Have you noticed that I am not one of the naysayer that shit's on crazy ideas? When I tell you you shouldn't do some thing... translation: imanent death. Yah you're getting away with it. Only a mater of time. Use a better set up.

Did I miss some thing? It was low res so maybe I'm not seeing it. WHERE'S YOU FUCKING HELMIT? For that mater I'd recamend knee and elbow pads and any other armer you have. Whrist braces is you have some clean enough. Ever seen a lock out? Don't know you but you seem a little too cool to be added to my, rather long, list of friends that have died.

I'm almost done with a spread sheet for you. It seems to be working fine but you and others here will have to go though and play with it looking for bugs. Busy now.

Lee


RiggerLee

Jul 25, 2012, 8:42 AM
Post #27 of 272 (4846 views)
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Re: [RiggerLee] My little project [In reply to] Can't Post

 
http://www.youtube.com/watch?v=eSxkmDOsdw0

http://www.youtube.com/watch?v=eSxkmDOsdw0

http://www.youtube.com/watch?v=GdE5DyqfUCg&feature=related

http://www.youtube.com/watch?v=zfHF0lRvm0M

This one's a staight up stall
http://www.youtube.com/watch?v=zfHF0lRvm0M

http://www.youtube.com/watch?v=-SzsItkSeRw&feature=related

An example of recovery
http://www.youtube.com/watch?v=NeqcH0YUDIw


Damn it. Couldn't find any really good carnidge videos. I guess people are squemish about publishing fatalities. But you get the idea.

Lee


Quagmirian  (A 110392)

Jul 25, 2012, 10:54 AM
Post #28 of 272 (4817 views)
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Re: [RiggerLee] My little project [In reply to] Can't Post

I value your opinion, but I can't help but be amused by being told by an American to wear a helmet. To address the whole tension issue, I am aware of it, and that's why I looped the tow rope round my chest strap; it'll break easily. I am aware of the inherent dangers of static line towing but it doesn't stop me doing it. Why not try to convince everybody out there who's on too small a canopy that what they're doing is dangerous. How about jumping without AAD's and helmets for that matter?


RiggerLee

Jul 25, 2012, 11:07 AM
Post #29 of 272 (4811 views)
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Re: [RiggerLee] My little project [In reply to] Can't Post

 
Ok, here's at least some thing you can play with. It's not perfect. In fact it's a little awkward to work with like all my stuff. I'm not a computer guy so there's some anoying little things in it that I don't know how to fix. Like how to make the graphs stay in proportion. But I think it's working right. Play with it and see if you can find any bugs. It should produice rib and panel shapes for retangular and eliptical canopies.

this took me longer then I'd planed but I wanted you to have some functionality. It's got a clark y in it right now but you can put other airfoils in. It lets you mush the airfoil around a bit. Opening up the nose by moveing the leading edge points up and down for top and bottom and forward and back for the bottom. You can change the thickness and the location of the thickness. Between all of that you should be able to smear it around to come close to other airfoils used on canopies. The cord line is the bottom axis along your bottom skin. It's set at 0 AOA right now. That gives you about 6 deg of AoA from your 0 lift line. Play with that you might want a bit more. You can set the estimated glide angle and it will rotate it around the free stream line going through the top of your riser keeping a constant AoA along the canopy span wise. As a place to beguin. Take your best guess. Monkey with it till it looks more or less like an existing canopy. Line the thing and then take it out and peg it down and kite it. play with the trim and get a feel for it's real glide angle, lift curve, and dynamics. Once you think it's workable go back to the computer and work the revised trim and AoA into the model and then start over. At least that's how I would approach it.

This is what it is. Two nights of fucking around. It's straight out of my ass so take it for what it's worth, every penny your paying for it. but it might give you a starting point to beguin playing with. And to all thoes who know better feel free to laugh at it.

I'd strongly advise saveing it as is and then playing with another copy. You can bugger it up easily.

Lee
Attachments: canopyb.xlsx (144 KB)


freekflyguy  (D 11658)

Jul 25, 2012, 3:03 PM
Post #30 of 272 (4775 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

Hey Phill, where are you jumping now?

I wondered why I hadn't seen you at Tily for ages, I guess the three riggers we have here weren't able to give you enough advice?


sundevil777  (D License)

Jul 25, 2012, 3:20 PM
Post #31 of 272 (4769 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

In reply to:
To address the whole tension issue, I am aware of it, and that's why I looped the tow rope round my chest strap; it'll break easily.

That's your solution?

Will someone else you know be willing to post on this thread to let us know what happened when you can't?


Premier Remster  (C License)

Jul 25, 2012, 3:34 PM
Post #32 of 272 (4763 views)
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Re: [sundevil777] My little project [In reply to] Can't Post

In reply to:
In reply to:
To address the whole tension issue, I am aware of it, and that's why I looped the tow rope round my chest strap; it'll break easily.

That's your solution?

Will someone else you know be willing to post on this thread to let us know what happened when you can't?

Didn't I raise this at the very start of this thread.. Oh, wait, yes I did...


Quagmirian  (A 110392)

Jul 25, 2012, 4:09 PM
Post #33 of 272 (4755 views)
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Re: [freekflyguy] My little project [In reply to] Can't Post

In reply to:
Hey Phill, where are you jumping now?

I wondered why I hadn't seen you at Tily for ages, I guess the three riggers we have here weren't able to give you enough advice?
Alright Buzz! Of course I know I could have asked you stuff, but you know once I start asking questions I don't stop! What does this do? What's the breaking strength of this? What are the advantages of this type of tape over type 3? Why have they used that seam? What's the importance of this angle? How do they do this... There aren't enough hours in the day.


sundevil777  (D License)

Jul 25, 2012, 4:15 PM
Post #34 of 272 (4750 views)
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Re: [Remster] My little project [In reply to] Can't Post

In reply to:
In reply to:
In reply to:
To address the whole tension issue, I am aware of it, and that's why I looped the tow rope round my chest strap; it'll break easily.

That's your solution?

Will someone else you know be willing to post on this thread to let us know what happened when you can't?

Didn't I raise this at the very start of this thread.. Oh, wait, yes I did...

Quite right!

I had heard of how towing can result in being slammed to the ground, and accepted as fact that it was a bad idea, but didn't understand it so well and had never seen it. After reading about it and seeing the youtube videos posted a few posts ago, of course it is easy to conclude that to rely on the chest strap breaking to prevent a lockout is not a good plan.

Anyway, if the OP is going to take such a risk, and it goes bad, having the result posted here might prevent others from a repeat.


Monko760  (B 38424)

Jul 25, 2012, 5:46 PM
Post #35 of 272 (4726 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

Success or failure =) Im looking forward to how this thread develops.


riggerrob  (D 14840)

Jul 28, 2012, 11:25 AM
Post #36 of 272 (4634 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

Hee!
Hee!
You sewed your stabilizers on back-to-front.
Remember that the primary function of modern stabilizers is to hold the slider horizontal, during early stages of opening.
When you sew the deep part of the stabilizer to the front of the canopy, the extra area holds the nose opening closed at low air speeds (see Service Bulletin on Para-Flite Cruisair circa 1981).

Oh!
And take a piece of advice from para-gliders to inflate both end cells before lift off.

Finally, take some advice from some one who has suffered head injuries (concusion, cut forehead, broken nose, etc.) during a crash, and wear a helmet. Brain injuries heal verrrrrrrry slowly.


Quagmirian  (A 110392)

Jul 28, 2012, 12:20 PM
Post #37 of 272 (4628 views)
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Re: [riggerrob] My little project [In reply to] Can't Post

In reply to:
Hee!
Hee!
You sewed your stabilizers on back-to-front.
Yes I know, I am so stupid for doing that. I actually designed the stabiliser like that on the computer just so I'd know where to put the line attachments, and I can't believe I didn't think it through. Now when the canopy sits in the deployment bag, a bloody great piece of fabric hangs out with the lines. Not good.

In reply to:
Oh!
And take a piece of advice from para-gliders to inflate both end cells before lift off.
It was open before I turned around, it obviously closed again due to my shitty stabilisers.


Blamey  (A 56669)

Jul 28, 2012, 12:44 PM
Post #38 of 272 (4622 views)
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Re: [Monko760] My little project [In reply to] Can't Post

In reply to:
Success or failure =) Im looking forward to how this thread develops.

I am on the edge of my seat. This just screams bad idea.


RiggerLee

Jul 28, 2012, 1:46 PM
Post #39 of 272 (4615 views)
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Re: [Blamey] My little project [In reply to] Can't Post

 
What do you mean? Bad idea? How do you think every body else got started? Ya think PD just sprouted out of the ground fully formed. No Thouse guys started out sewing building canopies in their spare bed room.

The guy is curious. He wants to learn. Not saying he wont die during the learning curve, especaly if he keeps up doing silly shit, but he's allready learned more about canopy flight, construction, and design then most will ever know. And if he's half way smart about how he goes about this there is no reason why he should have any problems.

I'm proud to chear him on. I wasn't much better off whet I built my first base rig. Now I'm building supersonic drogues for sub orbital recovery systems.

Lee


sundevil777  (D License)

Jul 28, 2012, 6:17 PM
Post #40 of 272 (4583 views)
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Re: [RiggerLee] My little project [In reply to] Can't Post

In reply to:
What do you mean? Bad idea?

Being towed up, thinking that the chest strap will break if he gets into a lock up situation. It seems like it would be much safer to launch from a slope, but of course not so convenient if a suitable hill is not available.


Quagmirian  (A 110392)

Jul 28, 2012, 6:31 PM
Post #41 of 272 (4568 views)
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Re: [RiggerLee] My little project [In reply to] Can't Post

Drew up a new stabiliser for this build which keeps all the slider stops the same linear distance from the risers, I hope that'll keep the slider in the right position.
Attachments: 9cell_lines_stab_new.png (34.4 KB)


RiggerLee

Jul 28, 2012, 8:30 PM
Post #42 of 272 (4557 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

 
Air foil looks reasonable if a little thick. What's the thickness ratio? Has the panel spreadsheet worked for you? I think you could reduice the lengths of your cascades, ie I think the point could be higher. Just for convenence of construction I'd make the B and D lines the same length. Now haveing said all that I'd lose the cascades entirely for now. It's easier to monkey with the trim with out them. And you don't even have to sew the tops. Just do like a sheet shank and the fingure trap it.


Lee


riggerrob  (D 14840)

Jul 29, 2012, 3:27 AM
Post #43 of 272 (4521 views)
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Re: [RiggerLee] My little project [In reply to] Can't Post

Yeah!
Whatever Riggerlee said, plus you might want to extend the stabilizers all the way to the trailing edge. Longer stabilizers will help (structurally) stabilize the rear corners (ala. Triathlon and Diablo).


Quagmirian  (A 110392)

Jul 29, 2012, 6:27 AM
Post #44 of 272 (4504 views)
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Re: [RiggerLee] My little project [In reply to] Can't Post

@RiggerLee That's not actually the precise airfoil I'm using, it's just representing the direction of the wing, in case you thought I was putting the lines and stabilisers on backwards. Wink The airfoil I'm using has a thickness of 15%. I'm not using the spreadsheet you gave me on this build, but I am keeping it for next time, definitely. I'll be using nylon cord tied with knots for the lines, initially, like on my white 7 cell. That will allow me to play with the trims before I commit to cutting and sewing a line set.

@RiggerRob I wanted a bit of stability in brakes, and I thought that chopping the stabiliser back halfway to the D line would do that, silly me.


Blamey  (A 56669)

Jul 29, 2012, 9:20 AM
Post #45 of 272 (4481 views)
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Re: [sundevil777] My little project [In reply to] Can't Post

In reply to:
In reply to:
What do you mean? Bad idea?

Being towed up, thinking that the chest strap will break if he gets into a lock up situation. It seems like it would be much safer to launch from a slope, but of course not so convenient if a suitable hill is not available.

Exactly this. It's not the building of the canopy that that worries me, I too am fairly impressed by the progress he has made. but the testing methods. Doing things that are known to be unsafe and not taking enough time to make sure you are being as safe as possible.


Quagmirian  (A 110392)

Jul 29, 2012, 9:56 AM
Post #46 of 272 (4471 views)
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Re: [Blamey] My little project [In reply to] Can't Post

If it makes everybody on this site feel better, I said I would never be towed at the airfield again. There are some hills near where I live, though.


mark  (D 6108)

Jul 29, 2012, 10:35 AM
Post #47 of 272 (4461 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

In reply to:
If it makes everybody on this site feel better, I said I would never be towed at the airfield again. There are some hills near where I live, though.

I see you have left yourself the option to be towed somewhere else, and you didn't say you would be using those hills near where you live.

Mark


AND1  (C License)

Jul 29, 2012, 12:42 PM
Post #48 of 272 (4440 views)
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My little project [In reply to] Can't Post

Phil do yourself a big favorer and stop your silly antics you have already been BANNED from one dz that i jump at because you was a danger to yourself and you can not call it a canopy its a very big kite and what happened to the orange kite you built nobody in there right mind will ever let you jump out of a plane with it and even a rigger tried giving you advise which you went mad at them because they was not telling you what you wanted to here,please stop before you really hurt yourself or others around you and from what i remember of you you dont no how to say no, its not you and if you carry on doing this project which you will you are going to hurt yourself really bad or others around you and for god sake WEAR A BLOODY LID and phil im not having a moan or a dig I'm only looking out for your safety and your life and fair play you have built somthing not many others will ever have a clue to do including myself


riggerrob  (D 14840)

Jul 29, 2012, 1:14 PM
Post #49 of 272 (4433 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

"
In reply to:
... @RiggerRob I wanted a bit of stability in brakes, and I thought that chopping the stabiliser back halfway to the D line would do that, silly me.
"

.................................................................

Stability in deep brakes is a complex subject. Hard-core accuracy competitors depend upon vented stabilizers, flares, keels, etc. to channel airflow in a predictable direction when the stalled airflow is trying to wander about at random.
To better understand stability in deep brakes, inspect an Eiff "Classic," NAA Jalbert "Para-Foil" of Performance Designs "Zero" canopy.


riggerrob  (D 14840)

Jul 29, 2012, 1:14 PM
Post #50 of 272 (4437 views)
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Re: [Quagmirian] My little project [In reply to] Can't Post

"
In reply to:
... @RiggerRob I wanted a bit of stability in brakes, and I thought that chopping the stabiliser back halfway to the D line would do that, silly me.
"

......................................................................

Stability in deep brakes is a complex subject invovling vented stabilizers, etc.
Hitn: look over an Eiff Classic, Jalbert "Para-Foil" or Performance Designs "Zero" to get a feel for how sophisticated their stabilizers are.


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