Wyvern Help

[SkippyBing]

Although I've got a plethora of information on the above beast, the one area I'm coming short is the gunsight. All the pictures I have of the cockpit seem to have had it taken out, save the one in the FAA museum, which being a TF.1 and not an S.4 doesn't have the same fit anyway! The sight is a Mk 4 E and according to the pilot's notes retracts, however although I've got some good images of a Mk 4 it's on a work bench not in an aircraft so I've got no idea how or to where it would retract.
Any help would be greatly appreciated.

[SkippyBing]

Shot of the cockpit, at the moment my main problem is the mount for the gun sight. I have pictures of both separately but not assembled and at the moment there's a bit of a gap between the vertical parts either side of the sight and the sight itself.
I'm 99% sure everything is to scale having spent several days staring at pictures of cockpits and comparing a shot of the sight in a Venom (same model) to the instruments to match things up.
I can probably finish it satisfactorily in the combat position, but I'd like to know how it retracted so I can animate that and have a fighting chance of seeing the runway on finals!

[petermcleland]

Skippy,

You need to look at the one on the Meteor 8 or the Hunter FGA 9...The Venom GGS did not retract. If you look at the Meteor 8 sight then that will be the same as the one on the Wyvern with manual ranging only from the throttle twist grip. The Hunter one has the same retraction system but has radar ranging and some extra indicator lights. The retraction system sends it down forward steep sloping ramps...one ramp on each side and slung under the two centre windshield side bars. The slope of the ramps is identical to the slope of the windshield. On the top of the left ramp and on its upper end about three fingers left of the side of the GGS, is mounted a dipole switch (Up to raise the GGS up the ramps to the top and Down to send the GGS down the ramps to the bottom).

To the right of the GGS, a finger width clear of the bottom right corner of the sight is a Red Knob to thump for "Emergency Retraction" if the electric system fails...I've never used that but you would use it to get the sight out of the way for ejection or crash landing.

The range drum on the left side of the sight rotates when you rotate the throttle twist grip...The ranges are marked on it from 200 yards to about 1200 yards.

The large rotating switch on the face of the sight is the "Wingspan Knob" and its scale is from about 30 feet to something a bit less than the wingspan of a Lincoln bomber.

Both the range drum AND the wingspan knob move the circle of diamonds around the central "Pipper" in and out (increasing or decreasing the diameter of the circle)...The pipper and circle of diamonds are projected out to infinity and they are what you see when you look out through the sloping glass of the GGS.

They are arranged so that if you set the correct wingspan of the target and then by twisting the throttle grip you make the circle just fit around the target and touching its wingtips, then the range drum will show the targets correct range, but more importantly the electrical current will be adjusted within the GGS mechanism to allow the pipper and circle of diamonds Graticule to LAG behind the fixed cross by exactly the right amount for the guns to be pointed ahead of the target to provide the correct deflection...Bullets will leave guns moving towards a point out in front of the target, so the target and bullets will meet at the point

I hope this has been helpful...I do have the Meteor 8 Pilots Notes and the Cockpit - Foreward View does show the retraction ramps and switches reasonably well. I can scan it for you if you wish

[SkippyBing]

Peter,

That was most helpful, and clears up which switches the Wyvern's pilots notes were referring to! If you could scan the Meteor 8's notes that would be most helpful. Of course the big question is if I can try and animate the sight diamonds in FS without going mad!

Skippy

[petermcleland]

Skippy,

It is too wide to display properly on here so I have uploaded a Zip file for you, of the "Looking Forward" picture in the Meteor 8 Get it here:-

http://www.petermcleland.com/dl/ForSkippyBing.zip

BTW...That black box on top of the GGS is the GGS Recorder Camera and I would leave that out of the model if I were you, as it gets in the way...We only had it fitted for Air to Air training sorties and we just had to put up with it. Operationally there was an external camera that would be used (G45 Camera in those days).

[petermcleland]

Skippy the second photo down on this post :-

http://www.cbfsim.org/cbfsim/cbfsBB/vie ... ift+Valley

shows the Graticule as seen through a Venom FB4 GGS

[petermcleland]

Just another quick explanation about how that graticule of light is produced...There are two circular super imposed metal discs...They each have a central hole (that makes the Pipper). One disc has six STRAIGHT radial slots cut in it. The other disc has six CURVED radial slots cut in it. The Wingspan knob rotates one of the discs (straight slots) and the other (curved slots) is rotated by the range drum. The result of rotating these two discs against each other cause six diamond shaped dots in a circle to move in and out, decreasing or increasing the diameter of the circle. The central Pipper is not moved by this rotation.

I hope this is not too complex to understand. I have tried to simplify the explanation as much as possible :flying:

[SkippyBing]

Peter,

Many thanks for the scan from the Meteor Pilot's Notes I should be able to sort the Wyvern out fully now. And thanks for the explanation of how the graticule was produced, a rather elegant solution to the problem in the pre video display age.

Skippy

[petermcleland]

You are welcome Skippy and good luck with the project

Edit...You may wish to know about the "RP" setting on the Wingspan scale...It means Rocket Projectiles and refers to the rather old fashioned ones from WWII.

You may have noticed that the circle of diamonds will rotate as they move in and out by using the WingSpan Knob, whereas they will just move directly in and out as you twist the throttle twist-grip and thus the Range Drum. The RP position on the WingSpan scale sets one of the diamonds exactly at six o'clock and this diamond is what you place on the target for the Rocket. There is a special range setting as well to adjust the distance of this diamond from the central Pipper. Thus the large Gravity Drop of those old rockets is allowed for. Another snag with using the Gyro Gun Sight for firing Rockets is its Low Launch Velocity and its Long Time of Flight compared to a Cannon Shell...This is dealt with by the RP Master switch which feeds a special very low current to the sight which will allow the graticule to LAG a long, long way behind the fixed cross compared to when firing cannons. This is all very well and will correctly give the proper allowance for the crosswind carrying the aircraft sideways down the dive...It will be necessary to bank to hold the circle of diamonds touching the target and this turn from the banking combined with the very low GGS electrical current and thus large LAG from the sloppy gyro will provide the proper deflection to allow for the crosswind. The problem is that with such a sloppy gyro, it would be impossible to get the bottom diamond on the target in the first place, as you come out of the manoeuvring "wingover" to commence the dive. The solution to this problem is that the "Camera Button" on the stick is brought into play when the RP Master Switch is set to ON...The current to the GGS is initially set to a very high figure, effectively "CAGING" the sight graticule...This makes it easy to manoeuvre the aircraft with some verve in order to get the bottom diamond on the target...Then when it is ON, you press the Camera Button on the stick and it UNCAGES the gyro Graticule which is now only controlled by the aforementioned very low current, and you can start smoothly counteracting drift by banking to hold the now sloppy graticule in place over the target. The GGS will now allow sufficient lag to allow for the long time of flight of the rocket.

[steve p]

Skippy,

Have you tried emailing Augusta Westland for info? Their archivist (Fred Ballam) is probably the most helpful guy in the industry and should be able to help. If you send an email to Augusta=Westland via their website it will get to him.

Best wishes
Steve P