0
Quagmirian

My little project

Recommended Posts

:)
You would think that there is some kind of computor program that would enable you to understand the effects of subtle changes in canopy configurations?

There isn't.

Therefore, keeping safety foremost in mind, everyone's comments early on in your postings, the good, the bad, the rude,...all apply.

You might just stumble upon something new and for that:

once again I applaud your efforts!;)
But what do I know, "I only have one tandem jump."

Share this post


Link to post
Share on other sites
Hi Quag,

Something that occured to me: Why not spread the rib/support tapes where they top out on the rib? This might spread the load(s) somewhat for a smoother topskin. As they are, they are point loading where they intersect.

Just something to consider,

JerryBaumchen

Share this post


Link to post
Share on other sites
JerryBaumchen

Why not spread the rib/support tapes where they top out on the rib? This might spread the load(s) somewhat for a smoother topskin.

From what I can gather, it seems to be a bit of a trade off. If I spread the tapes out too much, I think I will end with something like this:

[inline pd_reserve_small.jpg]

Taking it to the extreme, if the tapes were infintely close together, ie one tape going straight up, it would look like this:

[inline 300652_small.jpg]

I have moved just the c1 and d1 v tapes back a few inches, so I should end up with something like this:

[inline trango_small.jpg]

From my not very extensive studies, I have decided that I am more afraid of tapes being too far away from each other than too close. I'm sure you'll agree that all this isn't going to make too much of a performance change anyway, since I am working on relatively large, conservative 7 cells. Feel free to overrule me on this if you feel I've missed something.

Share this post


Link to post
Share on other sites
Here's something I forgot to post a while back. While it is beyond the scope of this project to manufacture live risers, I have been making some for ground handling and launching. Here's my latest effort (it's actually quite old) compared to a bought, and I suspect rigger made, riser. My thoughts so far? Accurate three ring riser construction is difficult and best left to manufacturers. I will not be jumping home made risers, as I consider them part of the H/C system.

[inline 3_rings.jpg]

Recently, I have been doing a lot of 'thinking'. While I am very happy with the performance of the brown thing, I think I can do better, particularly in the flare department. I have redesigned my ribs with smaller nose inlets and smoother profiles, in an effort for better glide and flare power.

One other thing, from now on I will be building canopies with fixed aspect ratios and at recognised sizes. While in the past I have made wings with areas of 'about 160-170 square feet', I will now stick as accurately as possible to known sizes, as in 135, 150, 170, 190 etc.

Here are the redesigned ribs, both seven and nine cell versions, in this case for a 150 square foot canopy.

[inline 139-2362_small.gif]

[inline 150-2571_small.gif]

Share this post


Link to post
Share on other sites
Quagmirian


Recently, I have been doing a lot of 'thinking'. While I am very happy with the performance of the brown thing, I think I can do better, particularly in the flare department. I have redesigned my ribs with smaller nose inlets and smoother profiles, in an effort for better glide and flare power.



Have you seen Ozone's patent for SharkNose? It would be interesting to see how that concept would work on a parachute:
http://downloads.flyozone.com/pdf/PG/ozone_shark_nose_en.pdf

Share this post


Link to post
Share on other sites
bofh

Have you seen Ozone's patent for SharkNose? It would be interesting to see how that concept would work on a parachute:
http://downloads.flyozone.com/pdf/PG/ozone_shark_nose_en.pdf

Thanks for that. I think that sort of thing is out of my skill level at the moment. Maybe when I'm building a high end swooping canopy, I'll come back to it.

I have been doing some more thinking, and I have decided that I want to put a single fold on the loaded bottom seams, not because it's any stronger, but because it looks a bit more professional. I've also changed my trim, rib and stabilser panels again.

[inline 2742_rib_flat_small.png]

[inline 2742_rib_stab_flat_small.png ]

I decided to use my scraps of old dacron to replace and extend my upper steering lines. It wasn't too difficult and they're all the same length +/- 0.25 inches. Good practice and now I have nice looking control lines. :)
[inline AK1.JPG]

[inline AK2.JPG]

[inline AK3.JPG]

Share this post


Link to post
Share on other sites
I have done quite a few flights on this thing now, including a glide down a 500 ft high slope, which was great fun. I have come to some general conclusions about the canopy in its current configuration.

Glide ratio is nice and flat, around 2.5:1.
Front riser pressure is very high.
Rear riser pressure is low, with a small control range before the stall (about 4 inches).
Flare power on the toggles is very good for a canopy of this size and type.
Control range on the brakes seems to be decent, although I haven't stalled it on the toggles yet.

Share this post


Link to post
Share on other sites
I've been doing a lot more ground launching. I went flying yesterday and it was very windy on the hill, so I got a decent bit of air time riding the rising air. I even got so bold as to try and stall the canopy. It didn't fold back on me, but it didn't look very happy either.

I took the canopy flying today with a couple of cameras. Here are some frames from the foot mounted camera.

[inline frame1.png]

[inline frame2.png]

[inline frame3.png]

This frame was captured just before landing, with the canopy in deep brakes.
[inline frame4.png]

Moving on the the future, here's a comparison of the rib sections and planforms of my old design, current canopy, and new design.

[inline ribs_compare_small.png]

[inline planforms_small.png]

Comments and criticism are always welcome.

Share this post


Link to post
Share on other sites
I've been going backwards and forwards on a few little things, but I think I finally have a design to replace the brown thing. The main design difference is the rib section, which is slightly thinner and smoother, with a smaller nose cut. There are construction differences too, addressing structural and quality issues.

General canopy info
Cells: 7
Aspect ratio: 2.10
Area: 170 sq ft
Chord: 2.740 m (8.99 ft)
Span: 5.754m (18.88 ft)
Colour: Not yet known, orange perhaps
Lines: 600 lb Dacron

Rib section
Max thickness: 15.0%
Position of max thickness: 19.4% (same as brown thing)
Nose cut size: 8.54%
Nose cut angle: 142°

Slider, standard
Chord: 0.44m (17.3 inches)
Span: 0.78m (30.7 inches)
Grommets: Brass, type 8

Line trims (mm)
A line 3108
A-B 66
A-C 216
A-D 458
UST 1200
LST 2716 Roughly
BK-TOG Don't know yet

Panel shapes (less seam allowance) and slider diagram

[inline parts.png]

Share this post


Link to post
Share on other sites
The "Orange Thing"? I'm sencing a trend here. Your doing well on your design and Ok on your construction, but you need to work on your marketing. Take my word for it. Cool names and half necked woman, you can sell any thing that way.

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

Share this post


Link to post
Share on other sites
mr2mk1g

Just so you know, whilst you might not be getting many replies recently, we are still reading and interested in your projects. It's great to read of someone 'mucking about' like this.



Very true..... Keep going OP

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

Share this post


Link to post
Share on other sites
skyturtle

Just out of interest, how did you work out the dimensions for your slider or is it just a temporary design?

The measurements are based on the slider from a PD 7 Cell. When I get round to jumping this thing we can work out if the dimensions need to be changed. It's just a starting point.

Share this post


Link to post
Share on other sites
I'm happy with all the seams on the brown thing, except the loaded bottom seams. Even if I hot cut everything, stuff still sticks out and I don't like the look of the raw edges. Also, the flat seam looks a bit thin in places. I would fold or roll the seam but all the bulk at the leading edge makes it very hard for my puny machine to sew properly, so I've come up with a solution. When I apply the leading edge tapes to the bottom skin and rib, I pre-fold the edges so that the tape only has one layer of thickness. It's difficult to explain so I hope this diagram helps.

[inline seams.png]

I've made an image of what the new canopy should look like based on the brown thing in flight.
[inline new_7_cell.png]

I've also decided on a warning label design and stabilser logo panel.

[inline canopy_logo_9a_small.png]

[inline warning_label1_small.png]

Share this post


Link to post
Share on other sites
There are a few things I don't like about the brown thing. Firstly, the control range is a bit short on the toggles (it's a flat trimmed canopy), and secondly, the turns are a bit snappy after about half brakes. There's plenty of flare power and toggle pressure though, so I thought I'd try and solve these problems by moving the most inboard control line half a cell outboard, like this:

[inline new_ust_config.png]

Any thoughts?

Share this post


Link to post
Share on other sites
Quagmirian

There are a few things I don't like about the brown thing. Firstly, the control range is a bit short on the toggles (it's a flat trimmed canopy), and secondly, the turns are a bit snappy after about half brakes. There's plenty of flare power and toggle pressure though, so I thought I'd try and solve these problems by moving the most inboard control line half a cell outboard, like this:



Any thoughts?



If I recall correctly, that's the exact opposite of the Triathalon mod (it goes from the "After" to the "Before" IIRC)
"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

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