Adjusting the canopy frame on an Arcus M

[[email protected]]

Hello All,

Our Arcus M canopy has always had a problem with proper closure and securement. Despite the passage of three years time, the problem is now better and worse not better. I have read all the advice and comments on a solution to this problem. The glider has been always hangared and cared for lovingly. We have had to abandon some flying days because of not being able to secure the canopy closed. We live in Michigan and have had problems on warm days, not just blistering hot days. The only solution seems to be sanding the canopy combing (frame), reducing the for and aft length of the frame.

Does anyone have any experience with this solution ? I have spoken to David Nadler who was most kind and who has had to do this himself to his Arcus before the "event". Heinz Weissenbuhler has been most kind as well.

All serious advice and recommendations will certainly be most graciously appreciated.

Sincerely,

[Duster[_2_]]

I fly as a guest pilot in a friend's Arcus T which has a similar, and quite severe, issue. Closes fine in the hangar, but once the sun hits it the canopy will not close. What always works is draping wet cloth over it before it gets hot. Seems fine after that, even back on the ground for awhile (caution; remove cloth before flight!). If the frame-sanding option is ruled out, one thing you might seek expert council (Mr. Nadler?) is to increase the bevel of the bayonet locking bars where they engage the receiver pins on the gunwale. Factory bevel is about 45deg and may not provide enough leverage force to mate with the oval pin opening. Not sure if grinding the bayonet is kosher. The factory has not been real helpful, unfortunately.

[Duster[_2_]]

I fly as a guest pilot in a friend's Arcus T which has a similar, and quite severe, issue. Closes fine in the hangar, but once the sun hits it the canopy will not close. What always works is draping wet cloths over it before it gets hot. Seems fine after that, even back on the ground for awhile (caution; remove towels before flight!). If the frame-sanding option is ruled out, one thing you might seek expert council (Mr. Nadler?) on is to increase the bevel of the bayonet locking bars where they engage the receiver pins on the gunwale. Factory bevel is about 45deg and may not provide enough leverage force to mate with the oval pin opening. Not sure if grinding the bayonet is kosher. The ones on the Grob 103 have a long, more shallow taper. The factory has not been real helpful, unfortunately. Hmmm, yet it shares the same fuselage as the Duo Discus.

[Tim Taylor]

Be careful using the locking pins to leverage the canopy closed. I had one of the anchor pins in the fuselage of my Ventus pull out from the extreme stress of closing the canopy in Uvalde.

[[email protected]]

On Monday, January 7, 2019 at 6:10:15 PM UTC-5, Duster wrote:
> I fly as a guest pilot in a friend's Arcus T which has a similar, and quite severe, issue. Closes fine in the hangar, but once the sun hits it the canopy will not close. What always works is draping wet cloths over it before it gets hot. Seems fine after that, even back on the ground for awhile (caution; remove towels before flight!). If the frame-sanding option is ruled out, one thing you might seek expert council (Mr. Nadler?) on is to increase the bevel of the bayonet locking bars where they engage the receiver pins on the gunwale. Factory bevel is about 45deg and may not provide enough leverage force to mate with the oval pin opening. Not sure if grinding the bayonet is kosher. The ones on the Grob 103 have a long, more shallow taper. The factory has not been real helpful, unfortunately. Hmmm, yet it shares the same fuselage as the Duo Discus.

I wouldn't suggest trying to force it closed.
Getting it wrong is about an $8000 mistake.
To find out where the interference is try slipping a narrow(about 1/2 inch wide) strip of paper between the canopy and the frame to find out where the interference is. It may not be where you think. That would provide some sense of where an experienced person might do a little sanding.
Been there- done that
Good luck
UH

[AS]

On Monday, January 7, 2019 at 2:52:30 PM UTC-5, wrote:
> Hello All,
>
> Our Arcus M canopy has always had a problem with proper closure and securement. Despite the passage of three years time, the problem is now better and worse not better. I have read all the advice and comments on a solution to this problem. The glider has been always hangared and cared for lovingly. We have had to abandon some flying days because of not being able to secure the canopy closed. We live in Michigan and have had problems on warm days, not just blistering hot days. The only solution seems to be sanding the canopy combing (frame), reducing the for and aft length of the frame.
>
> Does anyone have any experience with this solution ? I have spoken to David Nadler who was most kind and who has had to do this himself to his Arcus before the "event". Heinz Weissenbuhler has been most kind as well.
>
> All serious advice and recommendations will certainly be most graciously appreciated.
>
> Sincerely,

Had that issue years ago on an older plastic glider in our club. I am not sure if this was the original canopy or already a replacement, that was just poorly fitted. Anyhow, we used strips of carbon copy paper (remember that stuff?) over the ledge and repeatedly closed and opened the canopy. The carbon left nice rubbings indicating where to sand off the interfering material.
I am not familiar with the Arcus design but it may work there as well.

Uli
'AS'

[Hartley Falbaum[_2_]]

On Monday, January 7, 2019 at 2:52:30 PM UTC-5, wrote:
> Hello All,
>
> Our Arcus M canopy has always had a problem with proper closure and securement. Despite the passage of three years time, the problem is now better and worse not better. I have read all the advice and comments on a solution to this problem. The glider has been always hangared and cared for lovingly. We have had to abandon some flying days because of not being able to secure the canopy closed. We live in Michigan and have had problems on warm days, not just blistering hot days. The only solution seems to be sanding the canopy combing (frame), reducing the for and aft length of the frame.
>
> Does anyone have any experience with this solution ? I have spoken to David Nadler who was most kind and who has had to do this himself to his Arcus before the "event". Heinz Weissenbuhler has been most kind as well.
>
> All serious advice and recommendations will certainly be most graciously appreciated.
>
> Sincerely,

I had a similar problem with my DG808C.
I made a bunch of modeling clay 25mm spaghettis (length), about 3mm diameter. I laid them transversely on the canopy opening and closed the canopy and latched it. On opening, I could see right away where the pinch was, and about how tight it was. Sand and repeat till it is uniform. 3 iterations of this did the job.

Hartley Falbaum

[[email protected]]

My 2¢...

Some sanding will be required.

Keeping the canopy open vs “closed and covered“ will help minimise the amount of heat in the canopy. This isn’t practical if you plan to grid early and wait some time before launch, but if you leave the hangar and tow down and then get ready to launch moderately quickly, keeping the canopy safely propped open works better. Think about how quickly the cockpit temperature skyrockets when you close the canopy waiting for the towplane to take up slack vs just sitting with the canopy open. Yes, open canopies can be broken so it’s not a perfect solution.

[Karl Striedieck[_2_]]

A fellow pilot with an Arcus hit on an excellent solution and I'd mention his name but maybe he'd prefer not. He's probably reading this?

Take a stout pry bar along in the back seat and insert it under the left hand grab handle and then over the canopy frame cross bar that lies a couple inches in front of the grab handle. Prying up on the bar will allow the three locking pins to slide home.

Of course keeping the canopy as cool as possible helps. A white canopy cover is better than the common IR absorbing aluminum ones. If you have the latter, throw a white bed sheet over it.

Karl Striedieck

[Tony[_5_]]

$250k for a canopy that won't close. Daaaang.

[Muttley]

I had this posted on the Arcus Google Group ,which by the way you should join as you get some good information there (Schempp-Hirth Arcus) including discussion on Canopy.

I had the same problem with my Duo Discus and a Blue Tinted Canopy .

I got a Canopy Cover made up from a Material similar to Hyperkewl http://www.techniche-intl.com/technologies/hyperkewl/
Powered by HyperKewl - TechNiche Intl.
EVAPORATIVE COOLING HyperKewl™ Evaporative Cooling material is a unique fabric that absorbs and slowly releases water through evaporation. We look at this process as “super-charging” the bodies natural cooling process, thereby protecting the wearer against heat stress.
www.techniche-intl.com
You soak this completely in water for a few minutes, then dry the inside and i used to place it over the normal grey canopy
cover as not to scratch the canopy as the inside was a plastic material. I used to place it on the glider in the morning before
the Sun started to Heat up. Even the outside Fabric Skin dried up very quickly the evaporative cooling worked for quite a few hours
because of the structure of the inside of this material. The closing the canopy before the flight was no longer a problem and the
Cockpit was also at an agreeable Temperature. However you had to be reasonably swift between taking off the cover and
closing the Canopy for Departure. You also needed somebody to take the cover away as you could not store it in the Cockpit.
Mine used to live in a Coolbox. So it worked well during my stays in the South of France (St. Auban) and Spain (Ocana) and Australia (Benalla)
After a few years the Canopy settled down and I gave the cover to Uli Schwenk of Jaxida Covers, as I thought he could be interested in
commercializing the product. No idea why this was not pursued as in my opinion it worked!!

Bruno

[Bob Kuykendall]

On Tuesday, January 8, 2019 at 2:35:19 AM UTC-8, Tony wrote:
> $250k for a canopy that won't close. Daaaang.

The main issues here are design and the immutable properties of materials. The longer an acrylic canopy is, the greater its mismatch with the fuselage opening as it heats up.

Two-seaters with two separate canopies generally don't have these problems. Or at least, not to the degree such that heroics are required to latch the canopy. But apparently they don't look as good as a large single-piece canopy. And, of course, the two-canopy solution has a longer seal perimeter, with more opportunities for leakage and laminar flow disruption.

I think that if the manufacturers really want to make operational gliders with these long one-piece canopies, they should step up to the plate and do what is necessary to accommodate the almost inevitable thermal mismatch. It shouldn't be that hard to create an expansion zone at the aft canopy bow that accommodates up to 10mm of length change, sealed over with a mylar or similar strip that reduces airflow disruption.

--Bob K.

[[email protected]]

Three tips to close a tight canopy in hot weather.

1. When my ASW 24 was new and I went to Hobbs, I had to carefully sand the frame (rear center), as UH described.

2. Last year, the canopy became difficult to close in hot weather (this was both before and after the bullet holes, btw). "Helpful" ground crews were, at one point, slamming their fists into the rear frame until I finally got them to stop and gently *push down on the nose of the fuselage" to lift the tailwheel off the ground. That flexed the forward fuselage enough that the canopy dropped into place easily and I locked it down.

3. Also last year, it got easier to close when I waxed around the perimeter of the fuselage cutout where it touches the canopy frame in the labyrinth seal to reduce sliding friction. Before that, black paint from the underside of the canopy frame was sticking to the white gel coated fuselage cutout.

I don't know how applicable these tips are to a typical high-performance two-seater with a nose wheel, however.

Chip Bearden