C-47 Glider tow detonator

patelie · **Posted:** Sun Sep 14, 2014 5:09 am

Hello
Circled in red is the switch for the glider tow detonator.
But... which is the marking ??
Is there someone who can help us with that?
Thanks in advance

gliderman1 · **Posted:** Sun Sep 14, 2014 9:51 am

Patrick,
I do not understand your question..

But... which is the marking ??

On glider tow detonator:
The normal tow release on the CG-4A, CG-15A, CG-13A, Horsa was a mechanical (non-electrical) device. There was no need for a device to sever the nylon tow line which could be released mechanically from either cockpit. The only exception to this is the small sliding plexiglas door in upper center of glider windscreen (in some CG-4A gliders). This was purportedly so that a knife could be used to cut the nylon tow line if the release did not open. This little opening also was not purposefull on a CG-4A with the bolt-on Griswold nose protection device installed.

The only electrical actuated severing device I am aware of was on the outside of the C-47 just behind where the 3/8" steel cable exited the guide tube coming out of the C-47 floor. The only control for the explosive I am aware of was in the C-47 cockpit. It was two buttons that had to be pressed simultaneously to detonate the explosive to cut the cable. This existed only on a C-47 with the snatch pickup unit installed because it severed the steel cable and had nothing to do with the nylon line that was hooked on the end of the cable. Having a detonator switch near the rear door in C-47 seems strange because the crew chief or whoever could not see the glider on a snatch/tow and he had NO communication with the glider. His use of a switch to sever the steel cable would have to be only on command of C-47 pilot/co-pilot.

Do you have any more info on which C-47 model, etc this image applies to?

patelie · **Posted:** Sun Sep 14, 2014 11:43 am

Hello Charles.
Thanks for your input.
The image is coming from page 90 Handbook - Flight Operating Instructions - C-47 & C-47A Ref AN 01-40NC-1 dated 20 November 1944 and revised 2 november 1951 but page 90 was never revised
When I speak of the marking.... on the image we can see the plate (in black) which support the switch. top right of the switch is written 'ON', bottom left is written 'OFF'. And it seems that there are two lines on the top of the plate. I am searching the text which is on these two lines.

PS : For me the only control for explosive with two buttons in the cockpit was the BC765 (Detonator switch box) used to destroy the IFF and which is located on the top of the bulkhead behind the pilot

gliderman1 · **Posted:** Sun Sep 14, 2014 5:10 pm

Patrick,

Have photo given me by the man who flew C-47 for snatch tests at CCAAF, et.al. I do not have part number but suspect it was same box as you mention, which was red approximately 4 inches long, 2 inches wide and 2 inches high. As cable cutter, I doubt it would have been in C-47 unless at one time there was a model 80 winch in the plane. Lettering on box, DANGER Glider Pick-up Cable Detonator. On surface near the box is/was a notice: Arm switch at station 429 1/2 (which I assume in just forward of the door at rear of the cargo section) Before Making Pick-up. Safety Switch Before landing.

If me memory fails me, I get out my manuals and photos.....

Table 2, Pickup operator's check list shows number 18, Tell pilot cable cutter switch is ON and ready for pick-up.

Sure enough I look at photo of crew chief near door readying to release first glider to normal tow release, so they can go round and pick up second glider and there is a switch near the pick-up arm control box. I can not make the full text on the plate with the switch because it is behind the grab handle along the door. What I can make is this:
GLIDE _ _ _ _ _ __ K UP
CAB _ _ _ _ _ _ _ __ _
DO _ _ _ _ _ _ _ _ _ KE
PICK _ _ _ _ _ _ _ _ HEN
LIG _ _ _ _ _ _ _ _ _ ON

My imagination tells me something like this, Glider pickup cable cutter. Do not make pick-up when light is on.

So, the winch operator did have a switch to turn ON/OFF the two button detonator switch in the cockpit. However I can not image that all C-47 had this switch or notice --- only had it if at one time a model 80 winch had been installed in that aircraft.

shrike · **Posted:** Sun Sep 14, 2014 8:03 pm

gliderman1 wrote:

Having a detonator switch near the rear door in C-47 seems strange because the crew chief or whoever could not see the glider on a snatch/tow and he had NO communication with the glider. His use of a switch to sever the steel cable would have to be only on command of C-47 pilot/co-pilot.

But whichever crew member was stationed there would have had the care and feeding of the brake, reel, boom and associated hardware. Much better if he had a switch to cut things loose in an emergency than calling up to the pilot with a polite request when the doodie hit the reel , so to speak.

patelie · **Posted:** Mon Sep 15, 2014 3:26 am

Charles

Below is the picture of the control box which was used to destroy the IFF. We have one like that in the cockpit of the SNAFU.

OK. Charles, you are right. I found also the explanation in the pilot training manual for the C-47 :
Note : An explosive cable cutter is installed near the end of the torque tube to enable the pilot to disconnect the glider quickly in an emergency. Operate cutter by a 2-button switch located on ceiling of pilots' compartment above pilot's head. A toggle switch, above the arm retracting hydraulic selector valve, must be in the ON (armed) position before the button detonator operates.

So, this switch will not be installed in The SNAFU Special because she was never equipped with a winch and used for glider pick-up.

Thanks Charles for your help.

gliderman1 · **Posted:** Thu Sep 18, 2014 8:42 am

Patrick,
Switchbox is same except the up side has been painted over and re-stenciled with a warning that it is the cable cutter. When enlarged, the image I have appears to have faint signs of the original warning message as shown on your image including the switch part number as on the first line in your image.

The crew chief/winch operator controlled the circuit from the cargo section. He was supposed to disarm (turn off) his switch while preparing the winch, pick up arm and cable/hook for a pickup. After all was properly set, he was to arm (turn on his switch) his switch and tell the pilot they were ready for a pickup.

The winch crew could not detonate the cutter explosive from the cargo area and the pilots could not detonate if the switch in cargo area was off.

Because there were over 9,000 C-47 built and likely not many more than 300 or so winches, I believe, as you have decided, that winch related equipment was field installed and not installed when the aricraft were built.

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C-47 Glider tow detonator

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