Spitfire 400MPH or 480MPH ASI

No Graham,

Coastal Command used them too, the better to co-ordinate with the Royal Navy, etc.

Indeed, the Mossie swapped to Knots later in the war too! I went through my Pilots Notes and found a ton of guff on it and have lost my notes….my wot an exciting life I lead!!!

Knots is a far more sensible way to go anyway.

Regarding pilots notes being preproduction aircraft…not always true. Aircraft were initially issued with Provisional Pilots Notes which had no shots and then RAF Handling Squadron would complete the proper pilots notes after they had their hands on a ‘real’ service aircraft.

Given that the Halifax depicted has fluorescent gauges (note the later style r.p.m.s), there’s a very high probability that it was photographed in 1945, or postwar.

But aren’t we straying off the subject of 1939 480 m.p.h. ASIs?

And another thread to be open “When was first used fluorescent instruments”:rolleyes:

Cheers,

Olivier

We can always argue that this was taken in 1945

Given that the Halifax depicted has fluorescent gauges (note the later style r.p.m.s), there’s a very high probability that it was photographed in 1945, or postwar.

But aren’t we straying off the subject of 1939 480 m.p.h. ASIs?

It could also have been a Coastal Command Halifax…!

(It appears to be Merlin engined, if I read the boost gauge ranges correctly).

http://www.ovomalley.com/462_squadron_photo_album.php

Yes it could be … as well as Mr COOMBS could be wrong…

Olivier

It could also have been a Coastal Command Halifax…!

(It appears to be Merlin engined, if I read the boost gauge ranges correctly).

We can always argue that this was taken in 1945, but this Halifax used Knot gauge as well as many bomber command A/C.

Photo from:
http://www.ovomalley.com/462_squadron_photo_album.php

The text is from L.F.E. COOMBS book The Aircraft Cockpit (PSL)

Cheers,

Olivier

No Graham,

Coastal Command used them too, the better to co-ordinate with the Royal Navy, etc.

Thankyou that’s useful info:)

No Graham,

Coastal Command used them too, the better to co-ordinate with the Royal Navy, etc.

The Warwick was fitted 420 Knots gauge (if watching carefully the pilot’s notes), I strongly believe that there’s is no evidence of 480 m.p.h. A.S.I. on this plane. All the datas & limitations in the pilot’s notes are in knots to, needless to say that is duty asked for knots & wasn’t compatible with M.P.H.

Cheers,

Olivier

As far as I know knot gauges were only fitted to FAA aircraft during the war. Post war all aircraft were converted to Knots ASI’s.

Olivier,

We must have different Pilot’s Notes?

My copy, for the ASR 1, clearly shows an ASI calibrated in m.p.h. The text quotes m.p.h. with corresponding knots shown in brackets.

I have Provisional Notes for the GR 5. This does not have any photos, but the text refers to knots exclusively.

So I think you have a situation where the bomber versions would have had ASIs in m.p.h., but those later adapted for use with Coastal Command would have had ASIs reading in knots (same happened to the Whitley, Hampden, Beaufighter, etc).

My reason for mentioning the Warwick was to remind us that this aircraft was under development in the same time period as Graham’s 1939 ASI was manufactured. At this point, the aircraft was a heavy bomber. The prototype was flying in 1939.

Hence, another candidate to explain Graham’s early dated 480 m.p.h. ASI.

Yes indeed,;) I have a Warwick II & V Pilot’s notes copy, and I’m pretty sure that if once ever fitted (?) operationnally the 480MPH gauge didn’t last long.(first production Warwick to fly, May 1942 / 1st delivered ASR.I August 1943)
Coastal command ( but also some Bomber Command long range A/C used Knots even if they started with MPH ) for obvious navigational purpose.
I totally agree with you about the Whitley, Hampden, Beaufighter and the MPH gauge and as I previouly wrote the 480 MPH fits Beaufighter.

Cheers

Olivier

P.S.
Now, I think we really don’t have anything else to do to discuss endlessly about such subject (I’m part of it:D ) but in 1940 the USAAC had simple answer to simple ptoblem (question). The scan are from a 1940 technical manual, in the US to they owned high airspeed indicator, those indicators recorded 20MPH higher than the highest A.M. indicator (480MPH) at that time… and from 1942 (at least) they started to built 0-700 MPH gauges and that was only 61 miles from the barrier :dev2:

Olivier,

We must have different Pilot’s Notes?

My copy, for the ASR 1, clearly shows an ASI calibrated in m.p.h. The text quotes m.p.h. with corresponding knots shown in brackets.

I have Provisional Notes for the GR 5. This does not have any photos, but the text refers to knots exclusively.

So I think you have a situation where the bomber versions would have had ASIs in m.p.h., but those later adapted for use with Coastal Command would have had ASIs reading in knots (same happened to the Whitley, Hampden, Beaufighter, etc).

My reason for mentioning the Warwick was to remind us that this aircraft was under development in the same time period as Graham’s 1939 ASI was manufactured. At this point, the aircraft was a heavy bomber. The prototype was flying in 1939.

Hence, another candidate to explain Graham’s early dated 480 m.p.h. ASI.

For reasons best understood by Vickers-Armstrong and the Air Ministry, the Warwick also featured a 480 m.p.h. A.S.I.

The Warwick was fitted 420 Knots gauge (if watching carefully the pilot’s notes), I strongly believe that there’s is no evidence of 480 m.p.h. A.S.I. on this plane. All the datas & limitations in the pilot’s notes are in knots to, needless to say that is duty asked for knots & wasn’t compatible with M.P.H.

Cheers,

Olivier

What a fast fighter the Warwick was 😀

For reasons best understood by Vickers-Armstrong and the Air Ministry, the Warwick also featured a 480 m.p.h. A.S.I.

I have a piccie of the Whirlwind prototype, she had a 400 mph ASI.
As someone stated earlier, the pilots notes have 480 mph ASIs.

Might not be in that case but as example the pilot notes of the Spitfires are quite misleading. Because they show pre-production cockpits. So the picture of the pilot notes of the Mk IX shows clearly a modified Mk V panel, of the Mk XIV a modified Mk VII panel.
Regards,
Herbert

According to the Spitfire IX pilot’s notes, the maximum dive speed between Sea Level and 20,000 ft is 450mph IAS. So yes, it would read well into the range of this gauge!

I thought it would be something like that (he said, lying in his teeth 🙂 ), well I guessed pressure/altitude must have something to do with it.

My point is, a late Spitfire was capable of around 450 mph. Would the ASI ever read anything near that?

Just to throw a potential spanner in the works…

I’m not a pilot so have no accurate idea of the actual variation, but there appears to be a huge difference between IAS, Indicated Air Speed, and TAS, True Air Speed.

After glancing at the Mosquito tome earlier today, I think most of the IAS figures were only in the high two hundreds.

It appears to me that gauges reading to 480mph were only of use to see if the wings were about to be ripped off, not for general stooging, or even hurtling, around in level flight, except possibly at sea level. 🙂

Now you’ve gone and done it!! I have had to put my work head back on!!

Right….Indicated Air speed is what the pilot sees…IAS, add instrument error and you get calibrated Air Speed (CAS), add Pressure Error Correction gives Equivalent Airspeed, divide by square root of relative density and you get True Airspeed (TAS)……simple eh!? These are all airspeeds, never to be confused with ground speed…..

since the pilot of a WW2 aircraft only has indicated, flight planning would only be based on that, wind…etc….so what I am saying is that for our purposes we need not worry about CAS, TAS etc. Herring rouge.

Prototype aircraft would not have needed a special instrument in those days. Occasionally they have been known to have paper faces!! A 480 mph ASI was just a natural progression. I have Pilots Notes for most UK types so will have a looksee for a pre 1942 aircraft for Graham.

Olivier,

Sorry, I should have been clearer. VNE is the maximum speed in a dive (Velocity Not to Exceed)

Having had a quick browse, the Mosquito could achive 350+ mph in level flight with the single stage engines, and so it is reasonablt to assume that VNE would have been somewhere over 400 mph.

Bruce

To be pedantic VNE is indeed never exceed, but often there is a VD which is mad speed in a dive (design dive speed)

I have a piccie of the Whirlwind prototype, she had a 400 mph ASI.
As someone stated earlier, the pilots notes have 480 mph ASIs.

The fact is that often aircraft have had ASIs that go up to speeds the aircraft could only dream of. Just like your car does. Nowadays, it is known as ‘future proofing’ yuk.

Like aircraft, all gauges are built to specs….DefStans and Mil Stds nowadays.