I want to run the engine without the wings so that i can test everthing without having the hassle of fitting the wings which wonn’t go on in the workshop and so 5 mins running will be OK for that. I will almost certainly fit lorry intercoolers in the wing mounted rad cowlings, being a MKVIII it has two. We will circulate water from the tank in the tail through the two rads which ought to keep it cool. The fibre glass cowlings have given me some concern especially being very close the the exhaust stubs which is the major issue. At this moment I havent given it much thought, we have painted the interior with special paint that’s used on race cars but will probably replace them with alloy cowlings in the end.
There is no way of fitting a rad behind the engine there just isnt room,

Graham,

Actually, we concur on the first point. I do believe they were for prototype and early production aircraft – I just believe there would have been sufficient available to service all the manufacturers needs. Ross’ point confirms that they were already in production in January 1939.

As others have said, the aircraft would not need to meet 480 mph in a dive there should be a margin of error, so it never got that high, hence the 700 mph Mustang ones (now I know what they are, I wont sell them so cheaply!!). If you want aircraft that would meet this criteria, then any Spitfire will do. They may not have fitted them at this point, but they were capable!

I dont need a squadron of aircraft for my theory to hold water! They would have built them, and issued them to the factories as required. Yes, they would have stockpiled some, as they would certainly have more than one per aircraft. Heck, we overproduced some items on a massive scale! There would have been sufficient to allocate to the various MU’s, aircraft factories, airfields, squadrons and so on. I suspect they went wrong on a regular basis!

Mosquito aircraft were in squadron service in that timeframe.

These would have been essential equipment very soon after the 1939 date quoted. A year really isnt that long. As we know that many types were ordered from the drawing board, prior to resting of the prototype, there would have to be sufficient stocks available for issue to the factories as soon as the ink on the order was dry!

Oh, and thanks to others for the 420 knot correction – of course they are – it is just that 400 is the last number printed on the dial!

Good debate, and I wish I had a batch of them too!

Bruce

Phew, glad we got that settled, I am happy with this statement

I do believe they were for prototype and early production aircraft – I just believe there would have been sufficient available to service all the manufacturers needs. Ross’ point confirms that they were already in production in January 1939.

That was fun another thing I think we can all agree on “THERE AINT MANY ABOUT THESE DAYS”

Sorry Graham,

My copy of the Instrument Manual (AP1275) was reprinted in January 1939 and incorporates amendments 1-5 up to that date. It has not been corrected beyond Jan 1939.

“26. Mark IX instruments are manufactured in accordance with Specification G.280, and are designated in Air Publication 1086 under the following references :-

…

IXF 6A/587 Luminous 60 to 480 m.p.h.
IXF 6A/588 Non Luminous 60 to 280 m.p.h.
IXF* 6A/589 Luminous 50 to 420 knots
IXF* 6A/590 Non Luminous 50 to 420 knots”

* after the letter as per the dial fascia denotes a knot version.

So in production and given a stores reference prior to Jan 1939.

Regards
Ross

No need for appologies I would expect it to be listed as it was in production, I have one so it must have been. The question is does this prove in what numbers it was made and what its application was for operational or prototypes?

What was the quote from the BoB movie, “We need to either take off or blow up!” Hopefully your check valve will prevent the latter. 😉

Ever thought of an external ground unit radiator with fan unit that could be plugged in on the ground with quick release fittings? Gotta get that heat away somehow or it gets real expensive!

Not to keen on having any attachments, i think the wing intercoolers will do it if all else fails. Remember its a Meteor with 600 BHP rather than I think 1650 BHP Merlin in the MK VIII. It doesnt generate anything like as much heat as a Merlin.

You could put the 40 gal drum between frames 8 & 11,you wont need a seat, and it’ll keep your @rse warm!

Not sure about the effect on cooling however, I know a chap who made a “radiator” for his truck from box section welded together, even in the correct position and with a fan , it was useless (other than to provide amusement for onlookers!!

It’s also worth considering that if it is sealed and full of hot water, it will be deemed a pressure vessel i.e a boiler and these have to be tested by a (you’ve guessed it) Boiler inspector (if you are going anywhere the public).

It is unlikely however that a Boiler inspector will pass a 40 gal drum (walk passed, yes).

Well we could I suppose set up a shower room next to the spit when she’s running I think there would be allot of takers! a hot shower supplied by a Spitfire:)
Seriously though we are having a presure release on the tank. Tempartures will be monitored both in the header tank on the head outlets and in the holding tank. I dont hold out alot of hope for its cooling quality’s but am hoping the ammount of water in there will take 15 to 20 minutes to heat up. If he suffers from serious overheating we will had another system circulate water out to heat exchanges mounted in the wings.:)
Thanks for the info on the fuel tank, its perfect for our needs so i don’t think we will be parted from it.

this is true to a certain extent,but there are quite a few of early and pre war dated instruments about, this ASI so far as i know is unique.

You are right about 480’s not being in demand in 39,they werent required for operational aircraft until 1941 at the earliest.

Ah yes, but the point is it need not have been used in an operational aircraft. As James has said, if it was built for the aircraft that were coming next, then they would have built a batch and just put them on the shelf. The manufacturers could draw from them as required then.

I have a huge number of Mk9 ASI’s, and the dates are all over the place. I have ASI’s reading in knots that are dated as early as 1939 – a time when not many aircraft were using ASI’s measured in knots. My theory is that many were converted postwar when the ‘knot’ measurement became standard. To achieve this, the faces would have been replaced, and the instrument recalibrated, but it would have kept its original serial. That would explain the scarcity of instruments that read in MPH; it would also explain why more of my proposed ‘early batch’ of 480 mph ASI’s havent survived.

Bruce

I have been checking Alan Hulmes Illustrated guide to British aircraft equipment, by the way this is an excellent reference book. The 39 480 ASI is an MK IX F according to his info the MK IX D was introduced into operational aircraft in 1940 therefore logic follows that the MK IX F was introduced after 1940. Therefore this backs up my theory that instruments were not kept in stock for years. Why would instruments be made in advance it doesn’t make sense? Generally engine development i.e. more BHP drove advances in aircraft design the controls and equipment would have been designed as the aircraft took shape. I don’t believe its credible that ASI’s were produced in advance of the aircraft, can we really accept that an ASI couldn’t be produced quickly once testing revealed the aircrafts likely performance, all it requires is a new face and recalibration, a weeks work to set up?. Take the prototype Spitfire the Spade grip used on the protype Spit was a 1930’s biplane grip. If they didn’t have the grip finalised why they would produce instruments in advance for MKs still in the conception stage, let’s not forget that the 480 wasn’t introduced for operational use in Spitfire’s until the MKV. Can we accept that 480 ASI were produced in 1939 and then waited until 1941 to be fitted to operational aircraft?
The knots/MPH issue can be confusing but in fact for each MPH there is an equivalent version calibrated in Knots. The trick is to look at which MK IX it is i.e. A, B , C, D, E, F, or G. If my theory is correct your 1939 dated knots gauges will be MK IX D’s? The type face on the dial is age related rather than manufacturer, this can be seen by comparing other instruments of the period. I have attached a picture of an altimeter dated 1938 you can see this sort of more detailed tighter type face was in general use in mid to late 30’s, also early instruments have deeper cases. Another clue although there is exceptions, instruments pre 1940 have a ring painted around the outside of the dial which seems to have been discontinued after 1940 presumably to save production time.
If instruments were recalibrated to knots post war this would reduce their numbers in equal measure but there are still quite a few of early ASI’s of 240, 320, 340 & 400 around.
I think we have established beyond reasonable doubt that no operational aircraft used a 480 in either 1939/40. If you accept my reasoning that ASI’s were not produced and stored years in advance and that the ASI I have does not match the type face of the instruments introduced later in the war which would also discount the storage theory, then the only conclusion is that it was made for a prototype aircraft. Another quirk if you look closely is that it has 40 added at the bottom of the scale, this looks like it was added as an after thought or modification supporting the prototype theory. 😉 One other note. The 400 knot ASi was fitted to Mosquito NF38s in the early post war period. (ASIs calibrated in Knots, which were used by Coastal Command during the war, were adopted by other commands from the summer of 1945.)

Back to the list 🙂
Westland Whirlwind
Hawker Typhoon (expected, planned perf.)
Speed Spitfire
Heston Napier Racer[/quote]
Mosquito prototype?
Mk III Spitfire
Hawker Tornado

A few ideas, which expand on some already put forward, or may bring new light!

A quick check of my references shows that the early Mosquito was fitted with a 480 mph ASI. I dont have a picture of the prototype, but I do have one of the early PR/Bomber conversion. As they were essentially the same aircraft, it is reasonable to assume that the prototype would also have one. This aircraft was under development in 1939/40, and they would have required the ASI to be ready in that time period. 1939 is therefore perfectly reasonable. The same would be true of a number of other designs.

The instrument is to the same pattern as all the later ones – in other words, it was not designed as a one off, or short batch.

A small batch would probably still be more than 200 items to make it economical to produce.

Could anyone confirm the VNE of any of the aircraft either in service, or under development at the time. I would suggest that many of them would be between 400 and 450 mph, and therefore this would be wholly appropriate!

What you can confirm is that you have an early example of a 480 mph ASI Mk 9. I dont think you can ever determine what it was specifically made for (there is no one answer), though you may come up with a list of possibles!

Bruce

bRUCE

Bruce this all makes sense but it doesn’t explain why there arent more of them around. Although not common there are quite a few 400 ASI’s of that period about, but 480’s? the earliest date I have seen on one of these is 1941 Surely the early mosquito used 400? I think the PRU info is interesting. I believe a PRU mossie would have been faster than a fighter or fighter/bomber variant?The type face is different, the one I have reflects the design of that period used on altimeters ect.
I agree that we can’t ever put this to a single aircraft although a lsit of possibilities would be interesting. I stick to my view it was not used in an operational aircraft in 39/40 unless of coarse it was a PRU. I have attached pics to show the difference between the 39 and later ASI.