0
Tuiske

DIY canopy project

Recommended Posts

I'm not seeing any thing there that wont work, it's just not real pretty.

A few thoughts. Be careful with the velcro on the belly band. Try not to let it chew on your cutaway harness there by the ring. The cutaway handle is a little convoluted with the way the housings run. I realize you're working with what you've got and a single point is nice. You might convert the left side to be a little more like the right. Both housings tacked to a central pad on the chest strap. It has it's own awkwardness but it might be a more direct pull with shorter cables and housings. I use a double sided cutaway. The handles are on the back of the riser. In some ways it's cleaner and the action is totally away from the main cutaway. However the handles are on the back side of the risers. In a line twist getting a hold of them can be much harder. There are trade offs with every answer. A little bit of a pin cover would be nice. You could just do some thing with velcro on the bottom flap or build a top flap with a velcro closed cover on it. It's ugle but the bag is contained just fine. It would be nice if the pin were less exposed. You don't want to be loseing this thing on climb out and have a horse shoe.

You could make some jumps with that as it is but with a little work it could be cleaner. You really want this to be a safe workable system. If you don't like jumping it you will avoid using it when you should.

Lee
Lee
lee@velocitysportswear.com
www.velocitysportswear.com

Share this post


Link to post
Share on other sites
jumpsalot-2

What is the deployment sequence on this set up ? Static line ? Pilot chute ?

. Looks like a boc. On the belly container.
i have on occasion been accused of pulling low . My response. Naw I wasn't low I'm just such a big guy I look closer than I really am .


Share this post


Link to post
Share on other sites
Using the backpad mounted closing loop as a replacement for the top flap is simplistic but workable and clever. Saves building a flap.

But that lack of pin protection is a bit sketchy as RiggerLee said. It might be ok in a half full Twin Otter but scarier in a C-182. One would also need to be on good terms with the DZO to not get into trouble! (The more one has the trust of the DZO the sketchier the stuff they'll let you take on their expensive airplanes...)

The sharp turn of the cutaway cable when attaching the handle to the chest strap:
Easy to improve if you want - If the cutaway housings are tacked at their end, untack them there from the webbing, slide them out of the webbing loop they are in, and tack them higher up. Then one has a few inches one can bend gradually instead of making the cutaway cable do a sudden 90 degree turn.

Attached: extract from a selfie some years back, showing that feature along with the big cutaway handle I built.

Share this post


Link to post
Share on other sites
pchapman

Using the backpad mounted closing loop as a replacement for the top flap is simplistic but workable and clever. Saves building a flap.

But that lack of pin protection is a bit sketchy as RiggerLee said. It might be ok in a half full Twin Otter but scarier in a C-182. One would also need to be on good terms with the DZO to not get into trouble! (The more one has the trust of the DZO the sketchier the stuff they'll let you take on their expensive airplanes...)

The sharp turn of the cutaway cable when attaching the handle to the chest strap:
Easy to improve if you want - If the cutaway housings are tacked at their end, untack them there from the webbing, slide them out of the webbing loop they are in, and tack them higher up. Then one has a few inches one can bend gradually instead of making the cutaway cable do a sudden 90 degree turn.

Attached: extract from a selfie some years back, showing that feature along with the big cutaway handle I built.



Thanks a lot for the comments pchapman! I'm normally jump from C206 and if I'm sitting next to the door (first jumper) I think it's ok to not have pin protection flap. But I will think about that later.. could it be possible to built one to that kind of three flap desing?

For the DZO problem: my home DZ is not commercial and we don't have DZO. B| ..but I understand your point.

Cutaway housings are not tacked at the moment but they will be tacked. That loop handle looks nice on your photo but it looks also a bit scary to me. I feel it could be easy to make unintentional cutaway with that loop but it is sure easy to pull when you need it.
IG @skydive_tuke

Share this post


Link to post
Share on other sites
Like Quag I too would like to know the program you used to design the canopy. I have been around way to long to let you kids be that far ahead of me in things I have always wanted to do. Plus no jumping for me this year as I am laid up with a broken pelvis again. 6 weeks until I am weight bearing means i should be starting now. Hopefully I can do ss well as you two have done.

Thanks for the inspiration.

Share this post


Link to post
Share on other sites
I used SolidWorks 2015 for making 3d model. It was great tool to make surface model and it also has tool to make 2D patterns from 3d curved surfaces. It could be a pain to learn to use it if you don't have 3d modeling experience already. Canopy shape is not the easiest model to start that learning process. But good thing is that you can find heaps of tutorial videos from youtube to SolidWorks. I've been working as a 3d modeling engineer last 8 years so it was piece of cake for me to model this kind of thing ;)
IG @skydive_tuke

Share this post


Link to post
Share on other sites
d.dumanskiy

***Fuck yeah! Finally did the first jump.



Very cool! What are your plans? What are you going to do next?

I'm going to jump more with the canopy. It's now in my rig. I also started to design new canopy as well. We will see some day is that new design going to be something real.. B|
IG @skydive_tuke

Share this post


Link to post
Share on other sites
I have now jumped 10 jumps with this canopy. Openings have been ok, but maybe a bit too fast for being perfect. I'm going to make bigger slider when I have time for that. Current slider is from Odyssey 100.

There's lot of power on brakes and it is possible to pull brakes all the way down before stalling point. Front risers feels nice! Recovery arc seems to be a bit longer than on my 107 Stiletto, hoho.

But I also find out some weird behaving. Front corners of the nose make small "wobbling" when giving small brake input (maybe on half brakes) but when adding more brake it will be gone. Also on full flight canopy flies well.

I'm thinking maybe I should move "dividing point" of the A-lines little forward. On the attached picture there is current line setup on black, and my proposal for fixing this problem on blue.

What do you think?
IG @skydive_tuke

Share this post


Link to post
Share on other sites
Hmmm. I haven't jumped it, seen it, or really know any thing about how you generated the design. And I really don't know what the hell I'm talking about so keep that in mind when you solicit advice over the internet. It's worth every penny you pay for it.

Changes or flutter in the nose as you change angle of attack. The fact that it at the corners suggest to me that it relates to the, some people would call it twist of the canopy. You can really only optimize it for one aoa. Because it's curved AoA does not change constantly across the span when it pitches. And that assumes that it's not distorting. When you pull on the breaks and as the angle changes there will be distortion in the canopy relative to it's full flight which is distorted relative to it's sewn plane form.

So my guesses, coming straight out of my ass, are that as you start to pull down on your breaks you start to squeeze the tail on ether side flat. This elongates the trailing edge of those cells, they had shrunk when the think part of the back of the cell inflated. This makes the out side ribs tow inwards at the front. Depending on how you generated your plane form, the angle of attack probable varies across the span to begin with. Best guess is that you have a higher AoA in the center then at the ends. When the canopy starts to pitch back to a higher angle of attack the center increases more then the ends. Think of a canopy with 180 deg of bow. Think half a cylinder. The center is at Alpha but the ends are at 0 angle of attack. In fact they are at an Alpha angle of side slip. And if there is a trim angle to the canopy the end cells could actually be at a negative angle of attack. That's a really extreme example but it's helpful in thinking about how it changes.

So I'm not sure this is a trim issue. You might be able to address it that way but I don't think that is where the problem lies. Ultimately I think it might be in the plane form and how you generated your panels. It might help to think about the line that you rotated the airfoil around when you generated your panel shapes. Rather then it being horizontal maybe you should angle it along the glide angle for instance. Keep in mind I have no idea how you generated it to begin with. This would make the nose wider. More in line with the airflow so the changes when you pitch the canopy would be less of an issue. You can also build that inflation into the back of the panel so there is a bulge in the edge of the back half of the side of the panel. The trailing edge is narrower right before the tail. It lets the cell inflate with out shrinking the tail and changing the angles of the ribs. And when you pull on the breaks you don't get the trailing edge expanding as much. If you just sew it flat it acts like a spring. This locks it in more. It'a a paraglider thing.

So I think what you are seeing is from the elongation of the trailing edge as you start to apply breaks. As you get deeper into the flare the AoA becomes so high that it doesn't matter. It's all sully inflated at that point. I think the problem is in the panel set. I'm not sure it's a big deal but it may make your end cells more vulnerable to rolling under in turbulence like when you are on approach preticually if you make small break inputs like on final.

The trim change you are suggesting would basically make the nose a bit steeper. You don't really shift the location of the cascade point. It finds that balance on it's own. In doing so it distorts your line set at the cascade. You compensate for that in the trim. What your doing is trimming the A, B steeper reducing the angle of attack on the front half of the canopy. Don't see why this would help. If any thing I think you may find the out side cell to flutter more. Which would be an interesting test, but I think that if you were going to try to address this in the trim that the answer would be found in the other direction.

Keep in mind that all of this is straight out of my ass. Go tinker with it. Come back and tell us what you find. Sorry if this is incoherent. It's hard to verbalize and I've been interrupted a couple of times.

Lee
Lee
lee@velocitysportswear.com
www.velocitysportswear.com

Share this post


Link to post
Share on other sites
From the looks of the images in your very first post, it looks as though you might have rotated your rib about the horizon rather than a line parallel to the bottom skin or angle of attack. This is what I or Lee would call a negative 'twist' where the panels are narrower at the front, and it's a bad idea.

The end cells of any canopy naturally have a lower angle of attack anyway, so if you twist the canopy, it makes sense to make it zero (like I have done) or positive.

I hope that makes sense

Share this post


Link to post
Share on other sites
RiggerLee

.....So I'm not sure this is a trim issue. You might be able to address it that way but I don't think that is where the problem lies. Ultimately I think it might be in the plane form and how you generated your panels.



At first, thank you Lee for such a good analysis for my problem. Today I watched really carefully all the photos and videos I have, and I think you could be right on that thing. Maybe this problem is not a trim issue. I guess it could be brake like and/or stabilizer problem. Outer line of the cascaded brake lines could be couple of inches too short? It pulls the trailing corner quite a lot even on shallow brakes. And when that happend, stabilizer starts to make weird wobbling.

When making harness turns, canopy flies really well without any issues.

Harness turns: https://youtu.be/8XFHtFNQFbc

Opening the brakes: https://youtu.be/_Jieg4EvjBk

Also photo: outer-brakelines.jpg



RiggerLee


It might help to think about the line that you rotated the airfoil around when you generated your panel shapes. Rather then it being horizontal maybe you should angle it along the glide angle for instance.



This line is align with bottom surface of the airfoil. These pictures are from final design of the canopy and these shows a lot of how I designed it.

side.jpg <---this is maybe most important
top.jpg
front.jpg
center-rib.jpg
ribs_1-2,5.jpg
top_surface_1-2.jpg


RiggerLee


.....I think the problem is in the panel set. I'm not sure it's a big deal but it may make your end cells more vulnerable to rolling under in turbulence like when you are on approach preticually if you make small break inputs like on final.



...could be true...

RiggerLee


The trim change you are suggesting would basically make the nose a bit steeper. You don't really shift the location of the cascade point. It finds that balance on it's own.



That is true, but I think when moving cascade point more forward, could give more tension to line which goes to nose. Because there is only 3 lines on outer edge, cascaded line from front riser to outer edge cascades more "widely" than lines to other cells. But I also find out that the cascade point on outer lines is already little bit more forward from "middle point". I didn't remember that I designed it like that already :) ..so is is good on bad to be like that? Hmmm..

photo: outer-lines-cascade-point.JPG


And here is some testing on brakes and random pulling from all lines. I wanted to feel how much there's a tension in every line.

https://www.youtube.com/watch?v=zo_9iuVjfsU

Thanks to Teemu Hietakari for taking awesome photos!

outside_cam_canopy.jpg

-Tuukka
IG @skydive_tuke

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account. It's free!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
0