Going wacky over Wacos, a question about the CG-4A assault glider.

I have a puzzling question about the CG-4A Waco assault glider that I'd like the well informed minds here to ponder.

The CG-4A Waco had the ability to raise the front section containing the cockpit up out of the way for quick unloading. As soon as the glider came to a stop if it wasn't damaged and still sitting up right the crew could raise the front section immediately.

What I don't understand is how they managed the control cabling tension when lifting the front. I've spent a fair amount of time online reading pilot manuals and other writings pertaining to the CG-4A and I find no mention of what they did with the controls cables. It has become one of those minor puzzles that can be bothersome :) .

The thing about aircraft control cables is that they must be fairly taut to avoid control surface flutter and the control cables also have almost no stretch in them. If you look at pictures of the Waco glider with it's nose section raised you can see that any connected control cables would have to stretch at least half a foot or more and that is just not possible.

There maybe was some kind of quick disconnect but the speed at which they raised the front section would seem to indicate no as even quick disconnects for 3 of the 6 control cables wasn't the method. Maybe some kind of torsion pulleys that maintained the proper tension then shifted when the front was raised? There is no description of any of these devices in the online documents I have been able to find nor is the matter mentioned at all. There is also the question of the wheel brakes and the spoilers.

Perhaps the answer is staring me in the face and I'm just not seeing it. So if anyone knows the answer to this question or would like to offer up any ideas I would be happy to hear them.
 

Driftless

Donor
One photo of the cockpit shows the cables running up along the top. Maybe, when the cockpit was locked in flight configuration, there was sufficient tension for control, but then when the nose opened, everything was overhead?
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It doesn't appear to be rocket science. The nose opens and the cables bend. The cables, slightly above the hinge line, lose marginal tension but there doesn't seem to be any attempt to prevent kinking, so I assume it's not a problem. They were largely to be considered disposable. The easiest way to visualize it is to visit one and visualize it. Wheel brakes weren't a problem.
 
It doesn't appear to be rocket science. The nose opens and the cables bend. The cables, slightly above the hinge line, lose marginal tension but there doesn't seem to be any attempt to prevent kinking, so I assume it's not a problem. They were largely to be considered disposable. The easiest way to visualize it is to visit one and visualize it. Wheel brakes weren't a problem.

Good point Just Leo. I had considered that as the most likely solution but the thing is I couldn't be sure that the cables were above the hinge line. The available photos didn't provide a good enough look at the hinge area. Also it seem to me that if the control cables were above the hinge line they would be on the exterior of the glider. Which doesn't seem like a good idea. Now if the cables passed over the hinge line area and were exposed only for a very short length that could work. I think I'll study some of those old photos again looking for any indication that they were rigged that way.
 
I think Leo's got it - the gliders were never intended to take off again after landing, and it's fairly straightforward to re-tension the cables after loading.
Alternatively take a look at how bicycle brake and gear cables work in folding bikes - exactly the same problem, which has clearly been solved (albeit at lower tensions).
 
I believe the method of raising the nose was ingenious. Since the reason for raising the nose was to allow vehicles (mainly jeeps) to be loaded they simply ran a cable from the nose to the rear of the glider on pullies and hooked it to the pintle hook on the jeep. Then when the jeep moved forward the nose was raised!

and as far as running the control cables outside - Why not? It was fairly common in the days of wire-braced biplanes so the concerns were known and acceptable solutions had been developed. The main reason to put cables inside was to improve aerodynamics which wasn't a major concern on the Wacos
 
IIRC the control cable of the Waco passed through pulleys at the pivot point and hence the cables retained tension as the nose lifted turning about the centre of rotation. that is why the controls were led upwards to the top of the glider than along the floors as was normally the case. In the Horsa glider with the pivoting nose I believe all the cables either had quick disconnects or we similarly routed to the pivot point this time being on the starboard side of the aircraft.
 
The cable for the nose was mounted to a triangular frame atop the nose, which also served as the mount for the pitot tube.

There were no pulleys or guides at the pivot point for the cables, merely a transverse strap.
 
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Thanks to everybody who offered up their solutions to this little puzzle.

From further study of somewhat unclear online photos and consideration of the ideas mentioned here I believe that all control cables were strung over the top of the topmost rear main cross tubing of the front section. This would place the cables above the pivot point so when the front section was raised it would just introduce a few inches of slack into the cables and would not require any quick disconnect devices or such.

This didn't place any cabling on the outside of the CG-4A as there appears to be a space of an inch or so between the top of the cross tube and the underside of the plexiglas roof due to the plexiglas' frame mounts. The control cables continued on into the cargo section of the glider passing over the cargo section's top cross tubing and under the fabric roof where there was also a small gap between the fabric and steel tubing due to the framing that the fabric was attached to.

If the glider was capable of being flown again then after closing the front section just checking that no cables were kinked or off their pulleys should have been all that was required after closing the front section. And many gliders were in fact reused often by the snatch pick-up system where a C-47 would swoop down and snag a line strung between two poles to which the glider's tow line would be attached. It must have been quite a ride!

In the course of my reading I read many accounts of the crew training and operational use of assault gliders during WW2. It was a highly dangerous activity that required skilled and determined aircrew. As just one example picture making a night assault landing in one of these gliders in the days before night vision goggles. Even though the CG-4A was built sturdily from steel tubing in the cockpit and cargo sections if they ran into something while landing like a stone farm house or a full grown tree then it was likely to destroy the glider and prove fatal for some of or even all of the crew and passengers. Landing flares would help but also would expose the gliders to enemy fire.
The men who were willing to fly these missions had a lot of courage.
 
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