CReW trim tab construction

[andyhughes 0]

I'm interested in hearing about the various designs used to construct CReW trim tabs. I.e. what hardware combinations etc...

Would be cool to see some photos of different designs too.

[relyon 0]

The trim tab is a cam-lock type of device that shortens the [front] riser slightly and changes the overall canopy trim. It has the advantage that it doesn’t require any input (pull) once it’s set and is easily popped out to release; the disadvantage is that it can't easily be adjusted ad hoc and might (be) release(d) when that isn’t desired. It’s use has been superceded by adding one or more links to adjust trim where and when that’s needed.

I’ve tried just about everything that attached to risers at one time or another but haven’t seen a trim tab used in years (ca 1997). What are often used for CF are:

Blocks

Loops

2:1s (or 3:1s)

Line attachments (notably outside B-lines)

Also, if it has a loop it will often be a fairly large one kept open by a piece of wire (often cutaway cable) or surgical tubing. The loop is double layered and the expansion material is between the two layers. Except for blocks wrapped with Vetrap, I don’t have any pictures but can point you to these threads (read all the posts and there may be other threads):

2:1 Debate

2 to 1 vs B line attachments

Loops on rear risers?

dive loop modification

Hope this helps,

Bob

[pchapman 261]

Here's a pic from an MT-1 military rig I saw.

I don't know these things well, but I figure the routing of the webbing through the grommets is the 'standard' way it was done. The trim tabs I have on a canopy are sheathed in cordura so you don't see the inner workings.

[faulknerwn 36]

Why do you want them? I've been doing CRW since 1996 and have only seen them once - that was on a New Zealand CRW canopy. They're not very useful in modern CRW....

Or are you thinking of 2-1's?

[andyhughes 0]

Thanks for the replies so far - but keep the info coming if there are any other designs out there that were/are being used. The reason for the the info request is more for historical reasons - being a rigger and missing out on the earlier years of the sport. I've never seen trim tabs in the flesh, and very seldom come across 2-1s...

Actually, i'd also be interested in pics/designs of 2-1s too - if anyone has anything...

pchapman - that is a good photo, thanks - I can't work out how it locks though (is it just the two grommets that make a friction lock?)

[yoink 321]

Andy, some of the speedflying wings from paragliding manufacturers such as Gin and BioAir still use trim tabs on their risers.
There are pics on their sites.

I've already seen them cause one accident when they were miss-set.

[pchapman 261]

Quote

I can't work out how it locks though (is it just the two grommets that make a friction lock?)

Yeah just a friction lock. I haven't thought about it in detail. One would have to get the geometry right. But fundamentally I don't think the friction concept is really any different than for a chest strap adapter or especially a Parachutes de France style leg strap adapter.

[zoobrothertom 5]

That's the same setup I had on my Fury-220 for years. It was intalled by Skip Summers (of Prism) and Moon Mullins after I wrapped docking 10th with no arm strength left.

Just pull down on the tabs to set. You could even set it into a slow turn if you wanted. Just pull the red loops and it released. It lasted over 10 years and 800 jumps before one side snapped! Not bad.

It's reliable and I loved it when flying into a strong head wind. It made for a great landing when I forgot to release it.

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