Construction - Tad's primary release

[deltaman]

Hi,
I have got a tandem WW Falcon 3 and I am building a Tad's primary release on it with a smaller tube (better ratio). The one used for the tad 1 point barrel.

here some questions:

1- I need a trim anchor more forward than the one you show on your pics (trike speed>dragonfly).
Which length is better to increase ?:

or


2- Which length I need to decrease at the keel fore end ? tensioner or tensioner anchor ?..

3- no basebar setting for yet..
I want a pulley at the low end of the left downtube to pull at a 90° angle. No matter with Aeros wheels:

need an idea to protect the lanyard through the downtube hole (tube-eyelet ? guide on the basebar ?).. (see below, pic 5)
here, the bottom of WW tandem downtube:


4- Conduit Assemblies: Rather than a nylon tubing as a base I use a vinyl that I glue with the "stop" vinyl sleeve. And I don't see any matter..

5- Downtube pulley anchor: in the Falcon 3 tandem, screw is fore to aft on the top of the downtube.. How you would anchor the pulley like that ?


6- Release assembly mounting - aft anchoring:
don't really understand where to anchor the keel extensions
"The Harness is anchored on the cross spar sweep wire restraining bolt (or, better yet, the ball lock pin replacing it) inboard of the wires."

7- Basetube actuation system.
How much is the tension in your stretched bungees ?


Let's have a look on my pics for comments..
(I use a thread as the lanyard just for pics)
pic 1
pic 2
pic 3
pic 4
pic 5

[Tad Eareckson]

1. I'd strongly recommend leaving the Linkage the specified length and increasing the Lanyard length as required.

- Extending the Linkage limits your ability to trim aft/slower. That's not going to be much of an issue on this particular glider but if you ever wanted to use it on a solo with a bit of performance...

- The Lanyard is easily constructed/adjusted/replaced. The Linkage isn't.

2. I'd leave the Tensioner Anchor a short fixed length and adjust or replace the Tensioner line as required. That's easier and leaves you with less crap in the airflow.

3. The basetube bungee system is rather nice but DO make sure that's something you really want to do. Installation is a big and critical operation.

I want a pulley at the low end of the left downtube to pull at a 90° angle.

I don't understand this. That would have the lanyard exiting the downtube to a mostly horizontal path and you want it coming out straight down.

http://www.flickr.com/photos/aerotowrelease/8306300488/


If that were on the glider instead of on the model the downtube would be angled in as it rises to the apex and the lanyard would be vertical / coming straight down into the basetube.

Having the lanyard exit horizontally is what you'd want if you were going to pull the lanyard yourself instead of having the bungee do it. Then you'd be engineering as you would for a VG cord (which isn't a bad idea).

need an idea to protect the lanyard through the downtube hole...

If the lanyard is exiting the downtube vertically - as is the case in my configuration - just duplicate what I have done for my downtube.

If it's exiting horizontally after being rerouted around an internal pulley just mostly duplicate the basetube configuration:

http://www.flickr.com/photos/aerotowrelease/8306095455/


There's nothing protecting the Leader as it runs through the basetube because when it's under tension it's centered in the hole and isn't in contact with anything. (The drilling to achieve this condition is, of course, critical. Calculate is best you can, start out with a small diameter drill bit, and bias the opening if/as necessary as you enlarge.)

Rather than a nylon tubing as a base I use a vinyl...

The nylon tubing I use is hard and has a slippery feel to it. I would think you'd get better performance out of it.

screw is fore to aft on the top of the downtube..

Ooh... Hadn't considered that problem. It would always be lateral on gliders with faired downtubes.

I'm afraid the best idea I have is to drill for a small diameter lateral screw just below the extent of the plug.

don't really understand where to anchor the keel extensions

My glider - the HPAT - had a design which was very conducive to anchoring the release assembly.

In your fourth photo there's a cylindrical aluminum spacer through which the control frame apex bolt passes. I would anchor to that spacer and use spacers of some kind on the ends to keep the harness centered.

Your apex doesn't seem to match what's in the Falcon 3 owner's manual but it's what I have on my HPAT and I first anchored to that cylinder when I started developing my AT releases. Of course back then I was using a 130 pound Greenspot weak link so my chances of deforming anything were way less than zero. But you shouldn't be loading that release to more than 375 pounds and I can't imagine a problem with that kind of stress either.

How much is the tension in your stretched bungees ?

Bungee tension - like damn near everything else in aircraft design - involves a tradeoff. The greater the tension the more kick you can deliver to your release mechanism but the harder it becomes to pull the pin. I think at eighteen pounds bungee tension it was starting to require a little effort.

A max loaded Falcon 3 Tandem is 571 pounds.

With the Keel Release loaded to 375 pounds your towline tension is 652 which is 1.14 Gs.

My test results for my release gave a load to actuation ratio of 16.41. And you get a two to one boost from the pulley so 32.82. So at 1.14 Gs the bungee tension needs to be 11.4 pounds plus some more for safety margin.

And bear in mind that the bungee needs to take the slack out of the system first and as it contracts it starts losing power fast. So I'd want it stretched to be pulling eighteen pounds on the pin.

Let's have a look on my pics for comments..

1. It looks like you may be using perlon/nylon line for your Tensioner. The orange Tensioner line in some of my earlier photos is perlon. Not one that I noticed in the air but that was a mistake. Everything in the system should be minimal stretch. You don't want the release to be slapping back into the keel upon release any harder than necessary.

2. The drilling for your Basetube Pulley Screw appears to be high / off center.

It's difficult to keep things properly aligned when you're drilling tubing and here's what I do...

- Run one end of a long pin just through the factory holes for the tubing and tension the short end with a rubber band stretched along the tubing such that the pin will be set perfectly aligned with the holes.

- Clamp the tubing to something stable and use a plumb line to sight the pin and adjust to align the pin/holes perfectly vertically.

- In the vicinity of the points at which you wish to drill use a pencil to densely scribble marks across the top of the tubing.

- Place one end of a long construction level on the tubing and, while keeping the bubble centered, slide the end across the pencil marks to create a line across the top colinear with the top factory holes.

- Wrap a short strip of paper around the tubing and mark it where it starts to overlap to show the circumference of the tubing.

- Remove the paper, align the beginning end with your mark, fold, and mark the crease (so as to determine the opposite / half way point in the circumference).

- Measure from the end of the tubing to the point at which you wish to drill and mark on your scored line.

- Center punch this mark.

- Align the end/corner of your paper strip with the centerpunched mark.

- Wrap the strip back around the tubing and use the half way mark to determine the opposite/bottom point and center punch.

- If you need to drill perpendicularly to the factory holes fold and mark your strip to determine quarter/horizontal points.

I hope that made sense.

3. Make sure the inside of your tubing is cleaned out after drilling. Aluminum particles won't do pulleys or lanyards any good.

Really happy to see you doing this. Too bad the US is so dedicated to putting a thousand times as much effort into defending and institutionalizing the shit it put into the air decades ago as it is in doing the job right. I so do hope France kicks its ass and starts showing up at competitions with equipment that humiliates the Yanks and Aussies.

P.S. It really pisses me off that Wills Wing is selling tandem gliders they know goddam well are gonna be used almost exclusively for aerotow rides and training and are - for all intents and purposes - telling everybody to slap on a Wallaby release and use a piece of rope to tie it to the kingpost. What a shoddy crappy way to run an airline for decade after decade with no glimmer of a hope of anything ever getting any better.

[deltaman]

Thanks for all answers that I understood.
and happy new year.

I want a pulley at the low end of the left downtube to pull at a 90° angle.

I don't understand this.

yes you understood, not 90°, just horizontal.

screw is fore to aft on the top of the downtube..

I'm afraid the best idea I have is to drill for a small diameter lateral screw just below the extent of the plug.

I did anchoring between pulley and the screw head at the aft of the downtube. Pulley stands up on the end of the screw and the split ring (fore). Seems not so bad

Let's have a look on my pics for comments..

2. The drilling for your Basetube Pulley Screw appears to be high / off center.

bottom of the downtube you mean.. I don't think so

- Wrap a short strip of paper around the tubing and mark it where it starts to overlap to show the circumference of the tubing.

That's what I do


> Is there any risk of conflict between the lanyard below the keel and the main straps of the pilot and the passenger harnesses when they are moving their body weight laterally. I would think not as you can't move further than the downtube, and pulley is on the downtube and release anchor far forward..
I will try.. What do you think ?..

> As a lanyard I ordered some dyneema 1.1mm but I'm concern with spaces between the plastic ring of the pulley and its metal frame.. risk of jam ?..

> To avoid any slack in the lanyard and any twist, I will connect the leader to the lanyard just at its exit of the downtube whit the system pre-streched. A leader with an OD larger than the hole.

Thanks

[Tad Eareckson]

yes you understood, not 90°, just horizontal.

I still don't understand but I figure you know what you're doing.

I did anchoring between pulley and the screw head at the aft of the downtube.

Yeah, that would probably work - but it's best to keep the pulley as close to the tubing as possible.

That's what I do

Good. (Oh well, maybe someone else can benefit from the description.)

Is there any risk of conflict between the lanyard below the keel and the main straps...

Damn - I hadn't thought about that.

Yeah, that's something to worry about a little.

It's probably something more to worry about with respect to the release mounting harness as I had suggested it. Maybe a better suggestion...

Replace the bolts which secure the Control Bar Elbows to the Plugs with eye bolts and tie the harness ends to those.

Also... Wills Wing recommends a release trim position:

On keel, just behind the rear of the front keel pocket

But I wonder if you could get away with going just in front of the pocket. The farther forward you go the less of an interference problem you're going to have.

I found on my glider that I could go pretty far forward without noticing much difference. But, of course, the farther forward you go the more dangerous it becomes to lose the bottom end of the bridle.

risk of jam ?..

I don't know. I use one sixteenth inch Dacron leechline. That's a tiny bit less than 1.6 millimeters and there was no possibility of a jam.

To avoid any slack in the lanyard...

You need some slack in the lanyard because as the glider tracks away from the tug the harness rotates on the keel. When the tow tension pull is to the left slack increases and to the right it decreases.

...I will connect the leader to the lanyard just at its exit of the downtube...

You also want to do that to give you the ability to pull as much line into the basetube as possible.

Another comment I intended to make but forgot...

Where you're exiting tubing without benefit of an internal pulley - as at the top of the downtube - the shallower you can angle the drilled hole the better. I start with a one sixteenth inch bit and angle as parallel as possible with each increasing diameter up to a snug fit for the Conduit.

Happy New Year. Two more minutes left of 2012 in this time zone.

[Tad Eareckson]

P.S. Upon a review of your photos...

Pulley stands up on the end of the screw and the split ring (fore).

I realize you're talking about a clevis pin rather than a screw (or bolt). Yeah, that's a pretty negligible protrusion.

Also...

In my first post I was envisioning the trim point far out in front of the control frame apex. Should've checked the available material before writing. As I found in doing my homework for the previous post, you actually have very little room to work with between the apex and aft edge of the keel pocket.

[deltaman]

I want a pulley at the low end of the left downtube to pull at a 90° angle.

I don't understand this.

yes you understood, not 90°, just horizontal.

I still don't understand

I mean as a VG cord as we can see in my pic - a thread exit at the bottom of the (false) downtube:

Where you're exiting tubing without benefit of an internal pulley - as at the top of the downtube - ..

Why not puting the top downtube pulley inside the downtube too ?.. and tie the primary lanyard with eye bolts which would replace the ones that secure the Control Bar Elbows to the Plugs..

Is there any risk of conflict between the lanyard below the keel and the main straps...

Damn - I hadn't thought about that.
Yeah, that's something to worry about a little.

possibly more than "a little".. I will test that on the ground ASAP

Maybe a better suggestion...
Replace the bolts which secure the Control Bar Elbows to the Plugs with eye bolts and tie the harness ends to those.

don' t understand what that would change ?..

I use one sixteenth inch Dacron leechline. That's a tiny bit less than 1.6 millimeters and there was no possibility of a jam.

A 03/64 x 2005 millimeter leechline length serves as the Primary Lanyard.

??

I found on my glider that I could go pretty far forward without noticing much difference.

Yes I noticed that too.. can't correct the trim as I wanted on an old tandem with high pitch. How do you explain that ?..

P.S. It really pisses me off that Wills Wing is selling tandem gliders they know goddam well are gonna be used almost exclusively for aerotow rides and training and are - for all intents and purposes - telling everybody to slap on a Wallaby release and use a piece of rope to tie it to the kingpost.

The T2 (tandem from NORTH WING) is for me the best one (pitch and handling). I didn't try the new Freedom 220. Did you try to approach Kamron Blevins from NW ?

[Tad Eareckson]

I mean as a VG cord as we can see in my pic...

Yeah, I understand that. But I don't understand why you're coming out of the downtube horizontally if you're then immediately going down into the basetube.

Why not puting the top downtube pulley inside the downtube...

That primary release does a lot of moving. It:
- rotates around when the glider's tracking away from the tug.
- angles up and down with tension and pitch changes.
- gets moved fore and aft on the keel if/when the trim is adjusted.

A pulley harnessed to the outside of the downtube is a more fixed target.

I'm also thinking that it would be a little more of a pain to replace a lanyard or downtube with an internal pulley.

But an internal pulley approach may work fine so give it a try if you really want to. The worst that could happen is a little performance loss and lanyard wear.

don' t understand what that would change ?..

That would separate the ends of the harness and allow the suspension to pivot between the port and starboard halves with no or reduced interference.

A 03/64 x 2005 millimeter leechline length serves as the Primary Lanyard.

I need to check more and rely on my memory less.

So make that 1.2 millimeters. You should be fine with 1.1.

How do you explain that ?..

My best shot...

- Of course the tow tension is split so just half the bridle tension goes to the top.

- The bridle's coming into the keel at an angle so there's a downward vector component to the tension which helps trim and a forward vector which doesn't.

- As the glider trims faster the tow ring slides up the bridle so there's more forward vector and less downward vector.

Thus you're going to feel an inch of trim forward on the keel a lot less than you are an inch of trim aft on the keel.

Did you try to approach Kamron Blevins from NW ?

Have you ever seen him participate in any discussion about releases or weak links?

Have you ever seen ANY manufacturer participate in any discussion about releases or weak links?

It's been almost three decades since Gerard Thevenot came out with the Cosmos tug and aerotowing started to become mainstream.

Name ONE manufacturer from anywhere in the world - US, Australia, Europe - who has EVER shown the least interest in a built in release system or specified a weak link rating for a glider model.

ALL sailplanes have ALWAYS had good to excellent built in release systems and model specific weak link ratings. NO hang gliders EVER have.

Do you think that's just a coincidence? Do you think that's EVER going to change?

Hang gliding leadership is HEAVILY invested in keeping its population, students, customers stupid, confused, and poorly equipped. National organizations, local chapters, manufacturers, dealers, flight parks, schools, and instructors aren't going to tolerate anybody doing things right because that will open them up to lawsuits stemming from the decades worth of death and destruction they've caused by doing things wrong.

Keep up the good work but don't expect anything positive to come from the higher ups - ESPECIALLY from the higher ups in the US, the UK, and Australia.

[deltaman]

Thanks again..
I will soon finish it and will send you pics +/- vids on the ground/in the air after testing..
(actually bad winter weather)

I mean as a VG cord as we can see in my pic...

Yeah, I understand that. But..

Ok, I understood the misunderstanding.. I just want a VG system without going inside the basetube.. maybe later, but don't think that become necessary..

That would separate the ends of the harness and allow the suspension to pivot between the port and starboard halves with no or reduced interference.

but I thought about an interference between hanging straps and the primary lanyard below the keel not the harness of the release.

Where you're exiting tubing without benefit of an internal pulley - as at the top of the downtube - the shallower you can angle the drilled hole the better. I start with a one sixteenth inch bit and angle as parallel as possible with each increasing diameter up to a snug fit for the Conduit.

I made several tests on a piece of tube. But when you do angle as parallel as possible you open a long hole and then conduits fits worst..

- As the glider trims faster the tow ring slides up the bridle so there's more forward vector and less downward vector.

good.

Have you ever seen ANY manufacturer participate in any discussion about releases or weak links?

In France Hanggliding/Paragliding/Kitesurfing/Kite ..and soon boomerang, belong the same federation, the FFVL.
Manufacturers and the FFVL did some tests with the Kitesurfing releases, giving some datas for each tested devices as minimum tension, L/A ratio and break limit.. Some have got an AFNOR certification..
For yet the tow comittee (paragliding++) fears a certification for this kind of device and an official told me no official measures as it could push it..
Public datas seems to me good but I'm not so confident with certification organism, as I saw the defect of the DHV for example.. giving the certification to the SPACE (SEEDWINGS EUROPE) while that is a dangerous glider for unexperimented pilots which don't turn correctly ! and in the other hand refusing the certification for the first attempt of the RX2 tandem (ICARO) which was good but hadn't the right pitch for them..

For weaklink/release concept, Raymond CAUX read my AT manual inspired from yours and agrees with this way of understanding the activity. He has got the chair at the CIVL Safety Subcommittee..

[Tad Eareckson]

I just want a VG system without going inside the basetube..

I think that's the better idea - especially for a tandem for which you're going to be using a really heavy weak link.

Configure it just like a VG system is at that end. Run the Lanyard out horizontally and through a jam cleat to the button like I use for my Secondary Lanyard. After release just pull the Lanyard tight and cleat it to keep the upper components tight and clean in the airflow.

Damn near all of your separations - including emergency ones - will only require a light pull. And in a worst case high tension scenario you're still going to be able to easily deliver overkill pull to the lanyard/release.

but I thought about an interference between hanging straps and the primary lanyard below the keel not the harness of the release.

I first thought about interference with the Harness and forgot about the Lanyard.

And now it occurs to me that if there is an interference issue with the Lanyard that's another argument against the Basetube Bungee system. If you have a bit of slack in the system the interference issue isn't much of an issue. And a hand pulled system tolerates slack a lot better than a bungee pulled system.

But when you do angle as parallel as possible you open a long hole and then conduits fits worst..

I ended up with a long slanted hole and a nice snug fit with the Conduit. I'm very happy with the results.

In France Hanggliding/Paragliding/Kitesurfing/Kite ..and soon boomerang...

Boomerangs! I was heavily into boomerangs before and for a while after I got into hang gliding. I was a pretty solid competitor at the time it started getting organized and before it started getting specialized. (And for the last 35 years (this month) I've had a permanently dilated right pupil as a consequence of getting hit by somebody else's toy. If I had been wearing sunglasses I'd have been OK.)

For weaklink/release concept, Raymond CAUX read my AT manual inspired from yours and agrees with this way of understanding the activity.

You mean the way it's been understood with conventional gliders for the past century or so?

He has got the chair at the CIVL Safety Subcommittee..

I DO hope that that will count for something. But I also foolishly hoped that when Gregg Ludwig, the Chair of the US Towing Committee realized I knew what I was talking about and asked me to address the committee and help him rewrite the SOPs something positive would happen. But instead things almost immediately got much worse - with the SOPs being watered down even further and the Towing Committee launching a disinformation campaign (along with the issue of my ostracism and blacklisting).

Raymond knew Robin Strid and followed and was upset by all the crap written in the aftermath of his fatal aerotow launch - which pretty much boiled down to:

Whoa!!! The dude was killed by a shit release! Let's keep on using the shit release but force everyone to use insanely light weak links - which will solve all of our problems by breaking at the drop of a hat - and polypro towlines - to keep the insanely light weak links from breaking at the drop of a hat.

We've been mangling and killing people for decades because of shit releases, shit weak links, and the combination of the two without the FAI, CIVL, the FAA, USHGA, or any national regulatory body organization doing a goddam thing about it. But now things are going to change because somebody's read a document that makes sense?

Granted, the stuff we've written is comprehensive and solid but there's nothing in it that other individuals haven't been screaming about for as long as hang gliders have been towed.

I don't know what Dennis Pagen's current relation to CIVL is or how much influence he has but I can one hundred percent guarantee you that he'll use every ounce of it to protect the establishment and his reputation and extensive works of fiction and derail any move towards positive change.

Also note that:

- light weak links are fifty times as deadly to paragliders as stuff at the same G ratings is to hang gliders
- the UK forces all paraglider flights up on insanely light weak links

and CIVL has done NOTHING to address that issue.

I think our best hope for seeing any change is for people like you and Joe Street to get things into the air at their own operations, promote them, and educate people within their spheres of influence. And that education needs to include a section on identification of enemies.

[Tad Eareckson]

Oops. I see how I got confused about exiting at the bottom of the downtube.

In your first post you DID say:

3- no basebar setting for yet..
I want a pulley at the low end of the left downtube to pull at a 90° angle.

but I looked at your "pic 5" and that registered as a basetube.

Wasn't reading carefully and thinking clearly enough. Sorry about that.