Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: AKSWulfe on October 31, 2001, 01:18:00 PM
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First of all, why do both the 109 and 190 have the gunsight offset to the right?
I never could figure it out.
Secondly, didn't the 190A8 have the ability to carry twin 20mm cannon gondolas underneath it's wings? (2 20mm cannons for each pod)
I imagine it would add a lot of weight, but man that would be a helluva gunship right there.
-SW
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Hmm maybe 109's cockpit was so narrow that with throttle in your left side seat had to be installed right from centerline ?
Also right eye is usually dominating so that might be also one reason why sights were right from center ?
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The gunsight is offset to the right of centerline so that you can view the projected gunsight image without moving your head to one side. This applies to the use of a real gunsight mounted in a real airplane and is especially needed in the cramped confines of an Me 109. Your head would nearly rest against the left pane of the canopy if you were to attempt viewing the image projected by a centerline mounted site. Only one eye at a time can see the projected image, but that image appears to be straight out in front of the aircraft. You don't perceive it as being offset since the brain is combining the sight input coming into each eye.
You'll notice that the K-14 sights mounted on later P-51's, P-47's, etc, actually have two lenses and is twice as wide as other gunsights of the time. That type of sight projects two images (which are independantly switchable on and off), one for each eye. (The image seen by the right eye is the floating pipper w/diamonds and the left eye sees a fixed 70 mil ring/center cross).
A modern and sophisticated sight can be seen mounted on the helmets of AH-64 Apache pilots and gunners. The monocle only projects an image to the right eye but the pilot sees the image as though both eyes were perceiving it.
Try it live! Drop by a K-Mart (or any store with gun scopes), and ask to look through a Bushnell HoloSight, Tasco Optima2000, or similar projected dot sight. Hold it close to your eye and the image hovers 50 feet out in front of you. It doesn't appear to be "off to the side" because you are looking at the projected image and not the base/frame assembly that makes up the gunsight mechanism. Place it on the counter directly in front of you and try to look through it without moving your head. You can't see the image unless you move to one side! (unless you are a cyclops <G> )
MiG
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Or maybe reason was you couldn't see anything else than sights if they were front of you...
(http://people.freenet.de/tpics/M109Rebuilt-02.JPG)
Pic is from this topic (http://www.simhq.com/simhq3/sims/boards/bbs/Forum35/HTML/003275.html).
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Interesting, thanks for the info guys!
-SW
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(http://www.accu-flight.com/109site3.jpg)
(http://www.accu-flight.com/109site.jpg)
http://www.accu-flight.com/flightsim_photos.html (http://www.accu-flight.com/flightsim_photos.html)
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Some interesting photos regarding site placement in the Fw190 from this site:
http://planeta.terra.com.br/educacao/luftwaffe3945/fw190.htm (http://planeta.terra.com.br/educacao/luftwaffe3945/fw190.htm)
(http://planeta.terra.com.br/educacao/luftwaffe3945/fw190-1.jpg)
(http://planeta.terra.com.br/educacao/luftwaffe3945/fw190_painel.jpg)
F.
[ 10-31-2001: Message edited by: Furious ]
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a little off topic but heres a link to an agw thread about reflector gunsites
Reflector Gunsites (http://agw.dogfighter.com/agw//Forum3/HTML/024308.html)
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because they were too stupid to just draw a dot on the windshield? ;)
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Here's a note regarding the K-14 gunsight.
It did have two sight displays. One, a fixed reticle and cross, and the other, the reticle of diamonds.
The fixed reticle was intended as a back-up sight for A2A and as the primary A2G sight. The reticle of diamonds was a rudimentary A2A LCOS.
Both were intended to be viewed the same way...with both eyes open!
Depending ob which aircraft manual is read, the primary A2A operating mode was either with both displays in view (the "Fixed and Gyro position), or only the reticle of diamonds (Gyro Only).
Andy
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Great post! That makes so much more sense now. I thought the offset gunsight was in order to let them maybe lead better for certian attacks against bombers. The "one eye" thing makes much more sense.
CJ
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The K14 sight has a dial in which you clicked on what type of aircraft you were attacking. This may not have been a feature on all K14 sights.
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Minor correction needed!
The K-14 sight was not adjusted for target type. Instead, the sight controls were set for the wingspan of the target.
The diameter of the circle of diamonds was controlled by a rotating sleeve on the throttle. By "twisting" this, the pilot could make the diamond circle diameter increase or decrease.
Once behind the target, the pilot twisted the throttle to superimpose the diamond circle diameter over the wingtips of the target. This adjustment setting was used by the sight ballistics computer to compute range. This process is known as "stadiametric ranging" and involves the comparison of a known reticle diameter to a known target size. The result is range.
Stadiametric ranging is based on the idea that an angle of arc will span a certain amount of feet at a given range. Gunsight reticle diameters are made to be a specific size...the unit of "size" is called "mils" which is a unit of angular measurement (there are about 18 mils in one degree).
The basic idea is that one mil will equal one foot at 1000 feet range. If a gunsight reticle diameter is 35 mils wide, then a target with a wingspan of 35 feet will just fit inside the reticle at a range of 1000 feet.
In the K-14 gunsight, the reticle diameter size was sent to the computer by the throttle twist setting. The pilot had already told the computer what size target he is after. So the computer takes this wingspan value and compares it to the throttle input and computes range. For example, the target size is set at 35 feet. The pilot twists the throttle to match the reticle to the target wingspan. The computer then reads this value. Let's say the pilot had increased the size of the reticle to 70 mils. The computer would say, "target span = 35', reticle setting = 70 mils, therefore target range = 500'". This range value was used to calculate a bullet time of flight that was used in the overall lead angle calculation.
Besides range, the other major variable in the lead angle problem is target crossing angle. The pilot solved for this variable by keeping the sight pipper (center dot) on the target. He had to "track" with the pipper on the target for a minimum of one second before firing. This one second was known as "sight settling time" and was the time needed for the sight computer to reach a valid solution.
Pilots were taught a technique known as "track - shoot - track". This was intended to place emphasis on the need to keep the pipper steady on the target to allow the sight to compute lead accurately.
We still teach the same technique today.
Andy
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thanks andy........
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Hi Andy,
Here's some additional information from USAAF Manual 51-127-5:
"The P-51D carries a K-14 or K-14A gunsight, mounted on the instrument hood centerline. This sight contains both fixed and gyro-actuated optical systems, and computes the correct lead angle for targets at ranges of from 200 to 800 yards.
[...}
The K-14 differs from the K-14A only in that the latter has range lines on the fixed reticle; these lines are used for aiming rockets.
Earlier aiplanes of the P-51D series are equipped with the N-9 gunsight. The rheostat for this conventional optical sight is on the front switch panel."
Regards,
Henning (HoHun)
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Hi Henning
Yep...that's good info. Here's a picture of the sight. I cannot find out what the range dial on the lower left is used for. None of my aircraft manuals mention it. You have any ideas?
(http://members.home.net/alfakilo/K14.gif)
I sent you an e-mail with a forum post attached. Did you get it?
Andy
[ 11-03-2001: Message edited by: Andy Bush ]
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The A8 could carry underwing 20mm gondollas aswell as 30mm underwing gondolas, imgaine an A8 with 20mm and 30mm in wings + underwing gondollas.
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Hi Andy,
>Yep...that's good info. Here's a picture of the sight. I cannot find out what the range dial on the lower left is used for. None of my aircraft manuals mention it. You have any ideas?
The picture is right from the same manual page I quoted, but the range dial is not explained there either!
I'd speculate the range dial was mechanically connected with the throttle grip and could serve as a backup for the throttle twist.
However, it's primary function probably was to display the range to the pilot: If you look closely, you see a white arrow pointing at the near side of the range dial, and I guess there was a scale on the dial's circumference. That would be the means of indicating the selected range to the pilot.
>I sent you an e-mail with a forum post attached. Did you get it?
Now that I looked for it, I got it! Request confirmed :-)
Regards,
Henning (HoHun)
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HoHun
Thanks again for posting that for me.
Regards the range dial, here's my guess. I think it may be a way that the pilot can tell the sight what range he wants to see, taking into account the wingspan that he has also entered. The pilot then uses the reticle diameter as a measuring stick to estimate range.
Why would he want to do this? Perhaps he wants to shoot at his harmonization range. He then sets this range using that dial. Now when the target wingspan matches the reticle diameter, he is at his harmo range and has his maximum bullet density working for him.
Just my guess, as ill-educated as that may be!!
Andy
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Hi Andy,
>Why would he want to do this? Perhaps he wants to shoot at his harmonization range. He then sets this range using that dial. Now when the target wingspan matches the reticle diameter, he is at his harmo range and has his maximum bullet density working for him.
I agree, that's just the kind of tactic that requires the range readout. Whether the pilot actually turns the throttle grip or the range dial itself, the idea is to set the sight to a known distance.
Interesting that the range information is not displayed on the reflector itself - obviously, the HUD concept still needed to be invented :-)
Regards,
Henning (HoHun)