Graham Boak
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Posts posted by Graham Boak
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I entirely agree with that: I was perhaps too (not) impressed by an earlier posting claiming the C.201 and 202 wings were the same. I still see more of the C.200 in the C.201's fuselage profile than a pre-C.202. but the text is too vague. I would like to have seen a chronological bar chart of the C.200/201/202/204 showing design starts, roll-out etc.
You will love the book. Within this thread we are discussing what is a very minor aspect of a major work. There is at least a hint that it will be followed by similar books on the other fighter families.
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True for the manual examples, but "on the step" has two (or the same one at two different times) aircraft at the same speed and altitude but different flight characteristics. It's clear that the B-24 was not a properly stable flyer, but we are drifting away from the differences between the Mk.I and the Mk.II. I believe the explanations are linked, but not relevant to modelling either. We are in danger of having this thread closed. I suggest that if we want to go further into the aerodynamics/fight characteristics we need a new thread devoted to it.
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I'd just point out that reangling the thrust line would have major effects on the trim. Maybe that was desired? I do feel that either raising it or re-angling it would have been mentioned somewhere in Supermarine documentation, and probably in Boscombe reports.
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One comment I remember from reading about Libs in the Pacific, was the importance of what was called "getting it up on the step". Reaching the desired altitude by just climbing up to it was compared to climbing beyond the desired height, then settling down. The latter placed the bomber "on the step" resulting in superior range. As a simple-minded aerodynamicist I can't explain/understand this, unless it has something to do with different trim settings.
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I'm still working my way through the book, but it is clear that the differences go beyond the fuselage profiles. He states that only the empennage was common to the C.200 and C.202. I'm not sure whether he was considering the undercarriage or just the airframe structure. The two may have the same number of fuselage frames, in the same position, but they are different - thinner and less high. The wings are not the same either. The original leading edge was very sharp - it looks very much like a wedge and gave the kind of vicious stall/spin characteristic as might be expected. This was fairly rapidly modified to a drooped version, still looking very "wedgy" which was adopted for production. The general appearance should be fairly obvious on a decent kit - I only have the old Revell one and haven't looked. Yet: I suspect that when/if I make it it will require some work in this area. The C.202 had a revised section, much blunter and taller over the early chord. Fortunately the design allowed for replacement leading edges (back to the main spar, it seems.) If the rest of the wing differs, I haven't found direct reference
When he comes to discussing the C.204 project, he states this had a C,202 rear fuselage. I do find that he isn't clear on the precise timescales of the C.201/202/204 design process. They seem to be much more in parallel than in sequence. Is the slimmer fuselage of the C.201 a version of the eventual C.202 or only an interim approach? It clearly differs in the cockpit area.
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That was the entire point of the big tail: the Spitfire had outgrown its rear, with the growth entirely at the front. The later marks are a story of somewhat desperately fine-tuning what they could as long as Joe Smith had to put production first. I must admit being a little surprised that more isn't made of the lowered rear fuselage for the all-round vision canopy: the loss of side area aft cannot have helped.
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All the P-51s were treated that way.
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TS530 was an H-20,-FO suggesting that you may need to add the extra window behind the bomb-aimer's nose, but do have to have the bulged window above it.. There is also a different side-gunner's window with a raised sill. No-one has yet said just exactly what you get in the kit, in this area.
These may well be the kind of detail that can inspire some enterprising modeller to produce aftermarket bits. They would apply to quite a lot of Js too. Airfix have chosen a nose arrangement that fits (give or take only a bit) quite a lot of Liberators.
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I think that they all need a gearbox between the low crankshaft at the bottom of the V and the higher propshaft/thrust line, but I'm not sure of the details. The contra-props would certainly need a more involved gearbox, but I don't think that's relevant to this discussion. The 20series Spitfires all had a taller undercarriage to cope with the bigger prop than the Mk.XIV: raising the thrustline as well would seem an extra. Maybe it was needed?
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I'm reserving judgement until it is explained just how this was done, in view of the requisite possible changes. I can see two methods.
Firstly, a gearbox at the front of the engine to raise the propeller shaft. This might i n itself mean a modification of the nose shape, but probably not. It would require a different mark of Griffon. The foremost nose section would also be raised, changing the lines of upper and lower cowlings. This does assume, as seems most likely, retention of the Spitfire fuselage frames and engine mountings. I'm not sure that these necessary differences in the nose are visible in the photos.
Secondly, the entire engine could be raised. This would still require changes to top and bottom cowlings, quite considerable in the upper region, with higher fairings over the cylinder heads (surely resulting in pilot comment?) and raised exhaust exhaust pipes. This last should be visible. Plus major changes to the engine mounting structure. Plus what is happening beneath the engine? I would rule this option out, unless the changed position of the exhausts is confirmed?
So do the respective Griffons differ in the frontal gearbox, which raises the prop shaft relative to the crankshaft? If so, the stars align. If not, the LIDAR scans are cast in doubt. (Heresy!)
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Less drag than that chin thing. As demonstrated when RR was pushing their "power egg" approach, and they tried it on a Mosquito. I believe it was the fear of combat damage that led to the leading edge radiators to be abandoned (but see Fury) and I suspect the weight of protective armouring over such a span.
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Thanks, this is the tailplane to body incidence, which is what can be measured on the ground, statically. In flight, the wing will be producing considerable downwash so that the actual angle with the local airflow will result in a negative angle of attack, and downward lift.
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I think I said rather more than that. namely that the entire fuselage is too deep with the tail carried too high. What you have if a P-51B from the rear of the engine, not an Allison Mustang which would have a much smaller radiator bulge because the rear fuselage is lower. It is a familiar mistake on several kits were the makers have not looked at the aircraft.
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Late in the H-15 run, I believe. But often fitted in the depots or field, so like all types, check the photos of the one you are doing if you can
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It rather depends upon the period. The "Black box" kits were as good as anyone if not better. However that does include the P.23.
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2 hours ago, tempestfan said:
Pat Lloyd has drawn the tailplane with an essentially symmetrical cross section, and the elevators with the alternating "flush/step" arrangement, similar to the rudders. I have no idea if this has any meaning in the context.
Yes, increasing the area will increase the tail power. Methinks the contradictions go away.
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Have you ever considered actually considering at the points raised and seeing if you agree or not? Or is that below your standards?
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Orange? The Boscombe high-altitude calibration Javelin was red and white, as the photo shows. There is another thread where the red/orange discrimination is discussed, but there seems to be no way of coming to any conclusion. My understanding is that the Cougars were Red too. It quite likely the US colour International Orange, which is red in other languages.
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Changing the angle of incidence would alter the trim, and may well be part of the answer, but unless we have rigging diagrams I'm not sure how to find that out. I'd be surprised to find it had a lifting tail because I was told that such things were intrinsically unstable. A gust would not result in an automatic return but a divergence. But I was just a performance man so what would I know? Maybe @Zephyr91 might comment?
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Oughton states 21 a/c were transferred, listing the RAF serials, codes where known (usually) and ex-USAF serials and histories where known. Most are H-15s, with a few Js at at least one H-20.
The key matter still seems to be just what nose the Airfix kit provides, and how this might differ between the relevant production batches. Hidden in this is the question that if Airfix have based their kit on an L, does it match any of the BC Liberators? There were however a lot of White ex-Ls in SEAC, so going back to the original requests, examples are present. The details of the noses are in Consolidated Mess, which I went looking for last night but couldn't find.
So I slid my chair back a minute ago and guess what was filed under the computer desk? A quick look suggests that the actual differences are few, mainly a change from the rectangular window to a bulged one behind the nose turret (often modified in field to this fit) and similarly an extra window behind the bomb-aimer's transparency. However the L has a distinct kink in the forward fuselage to accommodate larger bomb-aimer's transparencies. Looking at the Airfix kit box art, this appears to have the nose of an H-5/10/early -15/FO. Phew.
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Consistent with having moved the tail forward, leaving the question "Why?" There must have been some reason.
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The difficulty as I see it is that extending the nose is destabilising in pitch and yaw, whereas adding a tail turret moves the cg aft and so is destabilising too (as is the top turret, aft of the wing, to a lesser extent). Both these features would require more tail, either a greater area or moving aft (or some other design alteration such as larger areas of tailplane and fin/rudder). Moving the tail unit forward would be counter-productive, making the aircraft less stable.
Therefore there is some other feature not discussed so far. Were the short-nosed Liberators excessively stable?
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Thank you Giampero. As an aside, I saw the Macchi on my Android phone, but the G,50V on Windows - though the Macchi has since appeared as I type.
I do have a double apology. I now find that Signor Caliaro does describe the C.201, twice. Once in passing in his section on the C.204. The description is followed immediately by "This aircraft would remain only as a paper project..." which is actually referring to the failure of the Isotta-Fraschini engine of the C.204. I feel this has possibly been the result of some confusion in the editing, Elsewhere, in an early chapter dealing with the competition between the C.200 and its rivals. he includes the photo you posted with a small amount of text. I'm afraid I was reacting to a couple of quick looks through the book rather than waiting to have read it fully - which to be fair would take some time to absorb.
But I do think he should have included the C.201 in a small section of its own. The book has an index but only for people.
This doesn't explain the drawing of the C-200/DB601 hybrid. Perhaps someone's idea of a joke? I'm glad I didn't attempt the conversion - although bearing in mind some of the things I did when I was much younger. it would have been quite sensible.
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As I understand it, the problem with the Falcon was the long time taken to cool it down compared with the short time it could stay there. Something likely to be much more suitable for a bomber intercept than the rapidly-changing conditions of fighter-fighter combat.
Vol 2 All the Spitfire questions here
in Aircraft WWII
Posted
Well, if it is confirmed, then they certainly intended it. However, they have just put a new and much larger tail on.. And now they run out of tail power?
This would also depend upon the precise relationship between the thrust line and the cg.