# P-47 D water injection switch on K-14 - equipped planes



## LukeFF (Oct 23, 2018)

I've been trying to find documentation on where the water injection switch ended up on D-series planes fitted with the K-14 gunsight. On "standard" P-47s with the reflector sight, this switch was on top of the throttle. However, when the K-14 sight was installed, a new throttle grip that featured only a microphone pushbutton was installed. So, that water injection switch had to end up somewhere. The only thing I've been able to determine is that the switch was moved to the sidewall on the N-series planes and modified to work in automatic or manual mode. 

Other than that, I've come up empty trying to find anything anywhere in cockpit images, manuals, etc., showing where this switch ended up. Can anyone shed some light on this?

Thanks!


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## whstlngdeath (Oct 30, 2018)

After looking at the engineering drawings, I've come to the conclusion that the reverse is true. If you look at the first pic I've attached, it shows the two throttle handles as a -1, and -2. The -1 handle is the one with only the mic button on top. I highlighted the -2 throttle handle which is the one with the water injection switch, (PN 96F71158-1), on top. Now look at the second pic, which is the title page of the throttle handle drawing, and I've highlighted the area that states which K-14 gunsight-equipped P-47 models use a particular throttle handle. It lists P-47D-35-RE and up use the -2 throttle handle, which is the one with the water injection switch. It's the later -M and -N models that use the -1 throttle handle. So it seems that at least some P-47D's, from the -35-RE on up, have the water injection switch on the throttle grip.

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## LukeFF (Oct 31, 2018)

That is really good info, thank you! That's some really interesting information about what sort of throttle was fitted to the various subtypes.

Now, I see at the bottom of the document that the drawing was originally drafted on 11 August 1944 and "Std" (Standardized?) January 10, 1945. That possibly leaves open the question of what sort of K-14 throttle assembly was used on models earlier than the D-35 (since we have combat reports of P-47s using the K-14 from the fall of 1944). I'm thinking primarily of models like the D-28 and the D-30. Would it have been the same throttle assembly as shown in this drawing? It would seem to be so, but I'm not sure.


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## whstlngdeath (Oct 31, 2018)

Here's another one. This is the drawing for the installation of the K-14 gunsight in P-47s. This one is not as clear, but notice the highlighted area, it denotes the earliest models that had a K-14 installed. It reads: "P-47D-35-RE UP TO P-47D-40-RE". These model P-47s would take a -3 version of the K-14 sight. The info boxes above this one shows various 'N' and 'M' models and their respective versions of the K-14. There is another drawing of the earlier P-47 versions before the -35-RE, and those used the Mark VIII gunsight. So it seems from Republic's own documentation, that the earliest model that Republic installed the K-14 is the -35-RE. I underline Republic, because the K-14 was installed in the field, at the various theaters, on other, possibly earlier models of the P-47, either through factory Mod kits, or maybe even by enterprising young field mechanics if they were so inclined. Now, back to your original question of where the switch might be on various P-47 models, we then have to know which model first received water injection. The earliest document I have seen is a drawing for a data card showing a schematic of the fuel and water injection systems. The drawing references the P-47D-15-RE model. If the K-14 gunsight wasn't installed until the -35-RE model, I wonder where the water switch was on the -15 P-47? I will have to do some more digging...

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## LukeFF (Nov 1, 2018)

This is really good info. Thank you for providing it! It's helping to fill some holes in my knowledge about the P-47.

Now, another big question about the K-14 as fitted in the D series P-47s: what particular model of the K-14 was fitted? I've seen the image of the K-14 as it was fitted in the N model (in the pilot training manual). Was this the same model used in the D series?

It looks like, from the drawings, the throttle was standardized by Republic in planes being produced from January 1945, and in the case of the D series, from D-35 onwards. My guess is that the new throttle grip that was a part of the K-14 targeting system was part of the field upgrade process that took place in the fall of 1944. It doesn't seem likely that, between August 1944 and January 1945, Republic would have used a different throttle grip design.

As for the throttle assembly in earlier models with water injection, I found this info in the pilot's notes in the November 20, 1943 edition. Of course, that does beg the question: when did Republic revert to the switch being on top of the throttle?


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## whstlngdeath (Nov 3, 2018)

A question I have is, what is the correlation between the engine water injection system and the aircraft's gunsight? Are they related just because of the K-14's throttle handle having the water injection switch mounted to it on certain models? Your original question still remains unanswered, which is , where was the water injection switch located in the cockpit before the introduction of the K-14 gunsight?


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