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#1
August 19th 03, 11:22 AM
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Long-range Spitfires and daylight Bomber Command raids (was: #1 Jet of World War II)
On Mon, 18 Aug 2003 20:39:22 GMT, Guy Alcala
wrote: Let's just say my reply has been delayed, but here goes. [snip more gratuitous and unprovoked logical discourse. NB all gallons referred to in this post are Imperial, not the inferior Yanqui oppressor's titchy competitive effort.] [Quill on longitudinal instability on Mk Vs] Ah, now we can compare close readings and interpretations of same. Onward. We agree on all the above, but I posit that the commitment would result in a shift to Mk. VIIIs (or Mk. IXs with similar tankage), accepting the likely temporary decrease in production. Actually I don't see there being a production shortfall, except at Castle Bromwich which would need some retooling to produce Mk VIII airframes instead of IXs as it ended Vc production in July - October 1943. The rear fuselage tanks could be post-production fittings at Maintenance Units, which would only receive as many airframes for fitting as tanks were available. So there'd be two deployment streams (short-range and long-range Mk VIIIs) until Boulton Paul or whoever else could produce sufficient tanks for full production fitting. Much like the behaviour of the actual Mk IX/XVIs with rear-fuselage tanks in 1945. True, but those Mk.IX/XVIs also had extra fuel in the regular fuselage tanks (ca. 94-96 gallons, depending on the source) forward of the datum. 66 or 75 gallons according to the Pilot's Notes and Shacklady & Morgan. And correct me if I'm wrong, but ISTR that only those a/c with cut-down rear fuselages got the aft tanks; Nope: the standard fuselage versions actually got larger internal rear fuselage tankage - 75 vs 66 gallons. At least that's what the Pilot's Notes say. [BTW, the VII/VIII/PR.X Pilot's Notes have some range/climb/cruise graphs which I think might be relevant to this discussion] and if you want to extend the escort range it's the amount of fuel you can carry internally to fight and return on that determines escort radius, no matter how much fuel you hang externally to boost endurance. Agreed. This is why the rear-fuselage tankage issue is critical to this speculation. Not for combat radius/return, unless you can use rear fuselage tankage for that; otherwise you're just extending the endurance and ferry range. This is how Supermarine and the RAF saw it: instability in the early stages of a flight was acceptable, providing that the fuel load had been consumed to the point of stability before the aircraft entered combat. As this is the attitude historically adopted with rear-fuselage tanks in the Mk IX/XVI, it's not such a stretch to invoke it a little earlier. The Mustang could only retain a fraction (ca. 25-50%) of that rear tank fuel to use for combat without being dangerously unstable, with the contemporary Spit possibly (probably?) being unable to retain any of it; Actually, the relevant testing in January 1945 revealed that the acceptable manoevering limit with the 75-gallon rear fuselage tank was 9.9 inches aft of the datum, or after 34 gallons had been used. Clearly the tank didn't need to be emptied for this to be achieved. at best, it could retain the same fraction as the Mustang. The Mustang with rear tank didn't have 269 U.S. gallons to fight and return on; it had somewhere between 205 and 227, depending on what fraction of the aft tank capacity allowed acceptable combat handling. In this case we have a Mk IX with 85 gallons internal forward tanks and about 40 gallons in the rear tank within apparently tolerable limits for combat. To be an acceptable long-range escort, the Spit still needed the extra forward fuselage fuel of the later Mk. IXs and the Mk. VIIIs, plus the leading edge tanks of the latter. The Mk. VIII carried 124 Imperial gallons internally (149 U.S), ALL of which was usable in combat, plus whatever extra fuel usable in combat (if any) a rear tank provided. Ah, here we disagree: as far as I know, most IX/XVIs didn't have enlarged forward tanks (in the traditional position forward of the cabin bulkhead, behind the engine), and most MK VIIIs seem to have been similar. So the best reliable figure for the internal capacity of the Mk VIII would actually be around 110 Imp galls. I suppose Air Commodore Alcala, Director of Fighter Operations in this scenario, will be pressing the Air Member for Research and Development to get them all with the enlarged forward tanks as well.... [increased tankage of 2 Spits IXs from Wright Field, July 1944] In the case of the Spit wing it seems to have been a strength issue, at least according to Quill Yes, but I suggest what Wright Field did was a reliable indicator of what the USAAF would have done if Spitfire production and procurement was within their grasp. A&AEE whinges about instability would get short shrift in this situation. . So I suggest basic experience of rear-fuselage tankage, and measures to combat the worst CoG issues resulting were at hand in plenty of time to have an impact on the postulated fitting of rear-fuselage tanks in the summer of 1943. The difference being that the flights to Gibraltar were ferry flights, and no formation maneuvering or combat flying with the aft tanks full was required. Sure, but how different is this from Vcs emptying them on the climb out of East Anglia and the cruise out to Holland? The short-ranged Spit Vs and IXs could handle combat in those areas, while the LR Spits would be briefed to pick up their escorts further out over the Zuider Zee. Giving them an extra 30-45 minutes of flight on internal fuel, even with the most restricted utility (e.g. only on the way in, no combat endurance to remain after entering combat) is still of use, and reflects the utility of giving them drop-tanks to start with. The final determinant is the distance over enemy territory a Vc could return on forward tanks alone after exhausting the rear tank, dropping the 90-gallon drop-tank and spending 10 minutes at high throttle settings in combat. This is obviously *not* a profile which makes it contender for deep-penetration escort, but it still means they should be able to operate out across Holland beyond Amsterdam and up to the German border. Even a marginal improvement like this would have had a real and clearly-observable benefit in supressing bomber losses. In the end, even the RAF cleared the rear-fuselage tanks for production usage in 1945, and they were happy enough to fit half of the tankage in the FR XIV and the full thing in the XVIII. Again, both a/c with cut-down rear fuselages. Yes, but the cut-down fuselage doesn't seem to be a factor in deciding whether a Spit got rear-fuselage tanks or not: the IX and XVI with conventional fuselage got them, the FR XIV got them and I suspect the XIV would have got them if it hadn't been succeeded on the production lines by the XVIII in 1945, which only came in a cut-down fuselage version. As it was, the example of the FR XIV and the IX/XVI indicates the cut-down fuselage actually had a lower capacity for rear-fuselage tankage (66 vs 75 gallons). Getting to our respective readings and conclusions on Quill, I note that he says in the case of the Mk. 21 that he disagreed with A&AEE on whether the Mk. 21's handling was acceptable at a certain point, and that he felt that such handling deficiencies could be accepted to get an a/c with superior performance into the field (he's also man enough to admit that he may have been overconfident by this point that average squadron pilots wouldn't have had serious difficulties, based on his own skills). I suspect A&AEE were right on that point; but it's instructive to see, yet again, that Quill states a fix for the stability and trimming issues that plagued the F.21 in 1944 was known about (enlarged tail surfaces), but production issues ruled it out until 1945. Take the MAP monkey off Supermarine's back, demanding production at the expense of development all the time, and this and a lot of other relevant problems could have been dealt with earlier. Now, it may just be a question of him not thinking to mention it, or the way he worded it, but he maentions no such disagreement between himself and A&AEE regarding the handling of the rear fuselage tank-equipped a/c; he just says that the handling wasn't acceptable for a long time, and required a lot of development. The origin of the "acceptability" comments over the rear-tank tests appears to be Supermarine's development testing. Aircraft would only go to A&AEE after they had arrived at what they saw as a production standard (e.g. Quill testing the 75 gall RF tank in July 1944, but Boscombe Down not getting it for another six months). Also, note that the A&AEE testing was not a peacetime acceptance test as such - the aircraft and fittings involved were often ordered into production anyway to minimise delays to production totals, and A&AEE testing was often being performed as representative of current or imminent production. F.21's were actually being produced before and after A&AEE first critically reported on them. I'm certainly not going to claim, based on such flimsy evidence, that this is definitive proof that the a/c couldn't have been flown in operations with an aft tank with accceptable handling much earlier given sufficient motivation, especially given your comments re the prevailing attitude of the A&AEE. But I do think it at least suggests that the Cg problems were real and agreed to be so by both the A&AEE _and_ Quill. And that's as far as I'm prepared to gaze into my crystal ball. Your reading may well be different. And it is, I'm afraid. A&AEE seem to get their first rear-tank Spit in January 1945, and quantify it as acceptable once 34 gallons out of the 75 were used. Nobody was going to Boscombe Down and pushing this idea, the whole issue seems to come from Supermarine. Posit a burning interest in the Air Ministry in increasing inernal tankage in 1943 (e.g. ACM Kramer getting upset) and I suspect things would have been remarkably different. I suggest with the equivalent of Eaker, Spaatz and Arnold lighting fires under people's arses to increase range in 1943, this would have happened earlier. Not Eaker or Spaatz; it was Arnold through Giles. From "To Command the Sky": I stand corrected. As to someone lighting fires for the R.A.F., that was what Pete and I were postulating, only for the Spit IX/VIII, with the highest priority to getting increased range British fighters in the U.K. soonest, with all other Spit improvements pushed back. Grabbing available Mk. VIIIs first (the MTO and CBI/PTO will just have to suck it up for a while), at the cost of MK.XII/XIV production, It wouldn't have been at the expense of Mk XII or XIV production if you're specifying a start after Schweinfurt II in October 1943. The XII production run had finished, the XIV was settled month beforehand and was going to start to appear in a dribble in December 1943 as production deliveries of Griffon 65s began. then either expanding Mk. VIII production at the cost of the Mk. IX That would have been possible, but only at the point of converting Castle Bromwich over to the VIII in the summer or autumn of 1943. This needs a demonstration of the effectiveness and need for it somewhat earlier: hence my LR Vs in 12 Group in July. or (if possible) transitioning to Mk. IXs with the extra leading edge tanks of the VIII, with aft fuselage tanks and whatever airframe mods required to pack usable _combat_ fuel in. That would have required prducing the VIII wings & airframe, I believe, rather than stuffing a Merlin 60-series into a Vc airframe as was done to churn out IXs. So I think there would be production infrastructure issues. As it was, the Supermarine production group around Eastleigh delivered about 90 Mk VIIIs to the RAF in July 1943, which should be enough to prove the concept if you grab them all. Sure, and that with an aft tank was next on the agenda after boosting production of the standard Mk. VIII/leading-edge tank Mk. IX. Either of the latter should have given us an escort radius of 250-300 miles. See my note on the actual forward-tank capacity of most VIIIs. Although this may have been changeable. Unfortunately, a similar chart for a Mk. V doesn't seem to be available on the site, but I have my doubts that the Mk. V was carrying around any such ballast in 1943, or if it did, so far aft. Of course, AB197 was a very early Spit IX (the report date seems to be June 10th, 1942), so that ballast was probably reduced as more operational equipment was added, but it at least suggests (combined with the Mk. V's further aft Cg vs.the Mk. IX as reported in various tests on the site) that the Mk. V was pretty much at the limit, while the Mk. IX had considerably more Cg range available. I can't find anything to substantiate this with the V myself, and I understand the validity of your reservations. Nevertheless, the critical issue as I see it is whether any rear tankage could become available given improvements in the CoG by means of the enlarged elevator horn balance and convex Westland elevator. I fully accept this would, in all probability, have been insufficient to allow a 75 gallon rear-fuselage tank to be carried and cleared for combat. The critical issue is whether this would have been enough to permit a rear-fuselage tank to be used in the early stages of flight to extend the pre-combat range. Given that this was done with a 29 gallon rear tank, I think there is a useable margin, albeit a smaller one than a LR-fitted Mk VIII with better weight distrubution and enlarged tail surfaces would have. I'm focusing on using the V not because it had more or even comparitive utility with the Alacal/Stickney LR Mk VIII (something I've argued for in the past myself), but because even with the greater constraints involved, it was a more likely concept-demonstrator in the historical timescale. If you want an overnight conversion to LR Spit IXs at any given point without the example of a LR operational trial in the RAF to start with, you'd have to posit the removal of most of the higher command and their staff involved to eliminate their existing preconceptions and prejudices. So this is why I think LR Vs would be an issue worth consideration even taking into account their inferiority from all aspects of the job when compared to the VIII. I think it's more credible to posit changes in the Vs proving the concept, as this would be more institutionally tolerable. This is important from my point of view, as I think any counter-factual speculation has to be made within the known constraints of the industrial, economic and institutional context to remain credible. [production pressures] I don't underestimate the pressures, I just think (as you mentioned a few paragraphs above) that if the decision had been made to go over to daylight, fighter range extension would have increased in priority and changes would have to have been accepted, whatever the disruption elsewhere. Because otherwise, it wasn't going to work. Indeed, but when the RAF actually faced this dilemma, at the end of 1939 and then again in spring 1941, they abandoned daylight bombing. The two concepts had become divorced, for understandable external reasons, and asserting a sudden and complete reversal of this is stretching the credibiluity of the institutional appreciation involved in the speculation. Now I think the concept is possible, and a valid piece of historical speculation, but I also think it has to work within the context involved, and, frankly, anybody demanding a reduction in Spitfire production in favour of speculative operational development was on a losing wicket. The British strategical position in this respect can't be overstressed too much: the USAAF had a doctine and institutional ambition towards independence which was served by the 8th AF campaign, secured by other forces doing things like protecting their bases and dealing with the existing war against Germany. They had room to stop and rethink tactics and strategy, and change production priorities accordingly. The British did not have this space. They had to maintain existing commitments and fight the war as it existed from a smaller industrial and economic base closer to the enemy threat. Proving strategic concepts, even ones which had great war-winning potential, was a luxury that could not come at the expense of the means for repelling the enemy in the meantime. The RAF could not prejudice production of their main fighter when it was needed for home defence, operations in the MTO and Far East and supply to the Russians. The difference between these commitments and facilitating daylight strategic bombing was the difference between fighting the war and demonstrating an abstract concept. Whatever happened in the skies over Germany, Fighter Command were conceiveably in a position to lose a war for national survival. The 8th AF wasn't. No lack of respect intended. The 8th might prove vital in winning the war, but high Spitfire production was known to be needed meanwhile to avoid defeat and stay in the war, which was an essential prerequisite. The Mk XIV was settled long before production started in October 1943, the number of airframe's you'd be losing in that year (six for development work most of which didn't need massive work for Mk XIV testing and ended up testing contra-props instead, maybe 20 for delivery to operational squadrons) is trivial. Simply cutting out the Mk VIII airframe allocation to the Mk XII production might free twice as many as that. And we'll be happy to take them, and we'll just have to accept the occasional FW-190 Jabo getting through. They weren't much of a threat on the larger scale, but if you're assuming a change of events in autumn 1943, the XII production run is effectively already over and done with. But we'll also take the airframes that became 610 Squadron's Mk. XIVs in January 1944. If you've got CBAF producing VIIIs or LR IXs in January 1944, which is perfectly possible if you start in July or August 1943, there's no shortage of airframes. Also, bear in mind production factor I've pointed out earlier - it's likely you'll have more airframes than rear tanks available by the end of 1943, so you might as well do something to enhance the remaining non-rear-tanked airframes. I really don't see either Griffon Spit (XII and XIV) having a substantive impact on LR Spit VIII supply in late '43 - early '44. I do think that the F.21 and later Seafires would have been delayed if Supermarine were working like demons on rear-tank stability problems in autumn 1943, though. But as I've already said, small loss. If we're talking about an operational need in the summer of 1943, No, the postulated date of the decision (to go over to days) was sometime in the fall of '43, although the exact date was a bit unclear. It seemed to be in the September/October timeframe, but we were unable to get ACM Kramer to be more precise. Well, pending a decision from "Butch" Kramer, let's assume either the first or second Schweinfurts as the PoD for this speculation. The faster the better, as far as the Controller of Research and Development and the MAP production executive are concerned: getting Castle Bromwich to produce Mk VIII wings and getting Boulton Paul to do the pressurised, self-sealing tanks are the major bottlenecks in the short term. Good points, and I don't disagree about the utility of the Mk. V as 'certainly better than nothing,' and better to lose people one at a time rather 7 or 8 at a time Again, my main concern with the V is whether they could in fact have been given the radius (not range). I appreciate the distinction, but I think increasing range was the first, and most easily achieveable step. I don't think the early XVIs actually had the rear-fuselage tankage when they first came off the production lines (September 1944), Right, I should have said the rear fuselage tank (and I think they only came in with the cut-down rear fuselage) about 16-18 months early, as i forget just when those versions came out, but I think it was only in '45. That's right. But while I'm always sceptical about blanket counter-factual claims about the relative ease of any one measure changing things, I have to say I can't see any overpowering practical reasons why they couldn't have arrived sooner, once the institutional prejudices and conflicting strategic alignments have been addressed. And I honestly think they are addressable. Please desist from this moderate rationality or I will complain to your ISP. Did I mention that I have INCONTROVERTIBLE PROOF that the U.K. government has been testing UFOs ( and dissecting ALIEN CORPSES) at their base at Machrihanish, Nah, you're just confusing Alien corpses with the average westie. Understandable mistake. We only retain them to give the midges a round-the-year locally-available food supply until the German tourists appear in the summer. cleverly disguising test flights of same as those by Aurora and, in times past, SR-71s? Wait, I hear the black helicopters coming to get me. I can feel the beams as they try to alter my brain. Excuse me while I done my tinfoil hat. Interesting theory, although it lacks credibility, until we acknowledge the critical role played by the Templars and the Illuminatii in the Ministry of Aircraft Production in 1942 [censored] Gavin Bailey -- Another user rings. "I need more space" he says. "Well, why not move to Texas?", I ask. - The ******* Operator From Hell 
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#2
August 20th 03, 09:20 AM
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#3
August 20th 03, 04:45 PM
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In article , The Revolution Will Not
Be Televised writes They all had facility for 2 pilots, e.g. extra controls could be fitted to the Halifax and Lanc if neccessary, but basically they had ceased to be 2-pilot aircraft by 1943. I'm not sure if they were intended to be operational with two pilots, I've only ever seen references to an extra set of controls if required, presumably mostly for training (although all the sources I have suggest training was done with only one set of controls). Most sources seem to suggest movement to/from the nose was awkward enough without extra controls getting in the way. Even for daylight ops, I'm not sure if a second pilot would have been carried, maybe the flight engineers would have received additional training (as some did unofficially from their pilots). I'm not sure when autopilots became common equipment (1943 perhaps?), they'd take some of the workload off the pilot. -- John
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#5
August 21st 03, 08:11 AM
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In article , Peter Stickney
writes In article , (The Revolution Will Not Be Televised) writes: On Wed, 20 Aug 2003 02:04:33 -0400, (Peter Stickney) wrote: SNIP lots That might be a reason for the Sutton Harness in a Spit- you wouldn't want the pilot leaning forward causing the airplane to nose down! The Sutton harness, because of that lousy pin-and-hole arrangement, was only ever capable of stopping pear-shaped people from moving around. RAF fighter pilots tended to be slightly slimmer... (Actually, I have doen this with light airplaes, to demonstrate the balance of forces to (captive audience) passengers - lean forward, nose down, lean back, nose up.) The refined version of this was carried out by a rugger team on a flight in a small airliner some years ago. While the stewardess was busy in the galley, the team members went to the back of the aircraft one by one (at a rate calculated by a pilot member of the team to make the pilot of the aircraft trim back slowly) and then at a given signal they all ran forwards again...yeeehaaaa! Cheers, Dave -- Dave Eadsforth
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#6
August 21st 03, 10:15 AM
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On Wed, 20 Aug 2003 22:46:44 -0400, Air-Vice Marshal Stickney, Air
Member for Research and Development, wrote: By all means, except I also note a depressing lack of nationalistic abuse in this post. Oh, well then, how's this: The last time a Brit tried to hand my family a line like that we threw his tea in the harbor. Now that was the kind of atrocity that should have featured in "the Patriot".... Still, an innovative approach to evading custioms duties and personal taxation which I'm sure is maintained as a family tradition under the IRS and the enlightened leadership of Lord Dubya of Shrub. Shame about Shay's rebellion, not to mention Sam Adam's interesting post-colonial take on sedition and the level of property ownership required to participate in a representative democracy. Ah, that feels better, now back to the mud-slinging of rational discourse. [rear fuselage tanks in Spit Vcs] That's going to take a lot of fiddly meaduring & figuruing to say for sure, but, looking over the inboard profiles (X-ray views) of both aircraft, one thing does stand out - a Spitfire's cockpit is aft of the wing, and well aft of the CG. And the fuselage ahead of the cockpit is already full of stuff. (Fuel, mostly) The available space behind the cockpit is a long way aft of the CG, which isn't good. A Mustang's cocpit is over the wing. The aft tank location is basically right at the trailing edge. Not only is the airplane more tolerant of how it's loaded, the tank location is in a better place. There's no denying it's a real problem. Agreed, but is this insoluable? The question doesn't appear as easily to definatively answer (either way) as it first appeared to me. Well, for teh Mk VIII and Mk XIV, it indeed was. FOr a Mk V, I'm not sure. See what you think over the sums when you get a chance. Actually, according to the A&AEE's reports on testing Mustang Is, and various Mk Vs, I don't see a whole lot of difference in altitude performance, even without the Mustang II's higher-supercharged engine. At 25,000 feet? There's no doubt the Alison Mustang was very useful below that height, but we need an escort force which performs well in the 20-25,000 or even 30,000 feet band. I'm dubious about the Mustang I in that environment, even more so with the Mustang II which I thought had a lower-altitude supercharger peak. It didn't climb as well as a Spit, adn it didn't quite turn as well, but it did out-speed, out-turn and out-zoom the Fw 190As that the Abbeville boys were flying. (Speaking of which, is Holly Hills still extant? I know he was recovering from his stroke a few years back.) Sorry, I don't know. Precisely. We need to posit a sufficient instiutional change of policy and interest to even begin this, but as nothing would happen without it, we might as well take it as a given. Well, I could begin my somewhat-factually based Nationalistic Rant about how the Brits, and Europeans in general never figured out how to put long range into fighter airplanes becasue their countries are so danged small, and that you can't ever be more than an hour from a National Border or coastline, unlike those of us who need to be able to fly stuff from San Francisco to Honolulu routinely, but I won't. Actually, I don't think that's sufficiently chauvanistic, in that I think there is a cultural dynamic relatesd to geography at work. However, the flip side of that is that the Europeans produced better interceptors in the early war period partly because of their willingness to cut weight (and fuel carried) to the minimum required for an area-defence fighter. Now I actually think the early US fighters (even the P-40 and P-39) were better than their later press made them out to be, but in this instance I think that for all it's shortcomings, the Spitfire in 1942-3 was the best type available in meaningful quantity for altitude combat, which is one reason the USAAF got it to replace the P-39. Getting more fuel into the Spitfire airframe, for all the difficulties, is a better option than trying to make the P-40 or P-39 a competitive high-altitude fighter. [2 pilot regime] The loading on the training infrastructure would increase, and the attritionally-supportable force would shrink, but then again BC took heavy casualties and expanded, and I'm not aware of a critical aircrew shortage: aircrew training slots seem to be over-subscribed since 1941, with pools of aircrew forming everywhere except in Bomber Command. The output of trained pilots is an issue, but then I'm not aware of it being inadequate historically. If anything, the British prioritised aircrew training too much in the period 1941-43 with repercussions elsewhere on the war effort (e.g. infantry replacements in 1944-45). It's a good question, though. If you suddenly start needing twice as many bomber pilots, the repercussions will be far & wide. Agreed, but look how many pilots BC were going through in 1943. 100% losses over 6 months is not insubstantial. If we can keep daylight raid losses within bounds, which I think is possible, we'll be no worse off even if we half the size of 3 Group's initial operational strength. Yes, but even the Wright Field Spits also had 43 gallon tanks behind the pilot, against 33 gallons in the wings (according to the A&AEE report summary on MK210 in S&M). Wing tanks have always been a given with me, as you & Guy have already specified Mk VIII airframes, which had 25 gall leading-edge tanks, but as Quill states, the only available space for major increases in internal fuel was behind the pilot. 43 of _whose_ gallons? I thought Imperial - were the 62.5 gallon Mustang underwing tanks used in that trial US or Imperial? They look bigger than 44/45 gallon RAF tanks. It's worth pointing out that the Wright Field modded aircraft used a somewhat smaller tank behind the cockpit, adn stucl 150 U.S. Gallons of fuel under the wings, where CG wasn't an issue. I'll admit to being a bit puzzled about why the RAF never went for wing rack mounted drops on a Spit, until it occurred to me that there isn't any significant amount of fuel in the wing, and teh plumbing and pumping is going to be a royal pain. I think some of this was dealt with with the Vc, in terms of structure and stressing for under-wing stores. I think 44 gallon ferry tanks should be a possibility. Well, the elevator balance change will add to the stabilizer/elevator combination area, and that's good. It also will reduce the control forces for pitch, possibly to the point whre the controls are over-balanced, and once you start waving the stick around, it wants to amplify the action, and that's bad, leading to overcontrolling at beast, and breaking the airplane at worst, especially with an airplane that's already pretty light on the controls, like a Spit. The bobweight tends to resist this overbalancing, at a cost in stick forces. The thing is, the amount of influence from the bobweight changes, like the elevator balance, with deflection. Absolutely. Over-tightening in turns was an issue, and this could only be evaded, not resolved, in a regime putting more weight behind the CoG datum. It's confusing, adn there's no intuitive answer other than make the tail bigger. The same applies to the rudder, as well. I'm going to give you those in new-production Mk VIIIs and IXs as a priority. I took that as granted for the LR VIII with a 75 gallon rear-fuselage tank. For the LR Vc, we don't need as much in a rear tank, and we only need it for 3 months or so as a proof of concept demonstrator before doing it for real with the LR VIII. Granted. But none of this works without the hierarchy breathing fire from the CAS on down for long-range escorts a la Arnold. Let me know what you think could be done with a range of figures, from 4 inches rearward travel on up, which seems a reasonable conjectural starting point for me. Don't forget to use the Vc airframe as a reference rather than a Vb in regard to landing gear. I'll get round to it, after... Demotion may follow as a consequence of disobeying my petty whims. Now, about those performance figures for Sabre-engined Lancasters.... [beer] After the Great Blaster Worm and Sobig Hydra chases I've had this week, that's top priority. (Work real job, than travel up to the North COuntry to help out some former clients) No beer for bad AMRD's. Just explain the priorities to your clients would you, there's a good chap? Gavin Bailey -- Another user rings. "I need more space" he says. "Well, why not move to Texas?", I ask. - The ******* Operator From Hell
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#7
August 22nd 03, 05:40 AM
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#8
August 20th 03, 09:42 AM
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The Revolution Will Not Be Televised wrote:
On Mon, 18 Aug 2003 20:39:22 GMT, Guy Alcala wrote: Let's just say my reply has been delayed, but here goes. [snip more gratuitous and unprovoked logical discourse. NB all gallons referred to in this post are Imperial, not the inferior Yanqui oppressor's titchy competitive effort.] [Quill on longitudinal instability on Mk Vs] snip Much like the behaviour of the actual Mk IX/XVIs with rear-fuselage tanks in 1945. True, but those Mk.IX/XVIs also had extra fuel in the regular fuselage tanks (ca. 94-96 gallons, depending on the source) forward of the datum. 66 or 75 gallons according to the Pilot's Notes and Shacklady & Morgan. I was referring to the increased tankage forward of the firewall. And correct me if I'm wrong, but ISTR that only those a/c with cut-down rear fuselages got the aft tanks; Nope: the standard fuselage versions actually got larger internal rear fuselage tankage - 75 vs 66 gallons. At least that's what the Pilot's Notes say. [BTW, the VII/VIII/PR.X Pilot's Notes have some range/climb/cruise graphs which I think might be relevant to this discussion] Yes, you're right about the aft tanks. OTOH, those a/c with cut down rear fuselages also had increased forward fuselage fuel and in some cases leading edge tanks (according to several sources which I take to be credible), and I think larger horizontal tails, so clearly they wanted to move the Cg back forward again (more fuel forward, less aft) and improve the stability. For instance, here's a post from a couple of years back on this subject: ------------------------------------------------ The Pilot's notes state the following tankage: The Spitfire 1/II/V had 85 gallons of internal tankage, in two tanks behind the engine and in front of the pilot. Additional fuel was carried in 30, 45 or 90 gallon "slipper" tanks under the fuselage. These were in common use after 1941. Early Spitfire IX's had the same internal tankage, while at the end of 1944 a further 75 gallons of internal capacity in rear fuselage tanks was provided. This caused CoG problems as described, but in reality they seem little worse than those experienced in USAAF Mustangs using a similar rear-tabkage arrangement. In late model Spitfires with tear-drop canopies (late '44 production), the front tankage was increased to 95 gallons while the rear fuselage tankage was reduced to 66 gallons (for roughly the same total tankage). Also, late production Spitfires had the leading-edge wing tanks used in the Mk VII/VIII for an additional 26 gallons of internal capacity. From mid-1944, the existing slipper tanks were augmented with longer "torpedo"-shaped drop tanks with a 50 or 90 gallon capacity. Spitfires operating in 1944 seem to have used the latter tanks very frequently, judging by the photographic evidence. The Spitfire VII & VIII formed the airframe basis for the later production Spitfires, and apart from some early Mk XII Spitfire's converted from Mark V's, all Mark XII and Mark XIV Spitfires had similar tankage arrangements of 96 gallon forward internal tanks and 26 gallons in wing tanks. Later Mark XIV and Mk XVIII Spitfires had rear fuselage tanks, either of 62 gallons capacity. Early Mark XIV's (examples in the RB-serialled series at least) did not have rear tanks, and seem to have had Mark VIII-arrangement (with reduced forward tankage capacity previously mentioned) and I suspect the rear fuselage tanks only arrived with the later production Mk XIVe models, again after mid-1944. Some examples of the Spit V had a smaller rear tank, though I believe this was used for ferry only. That's correct. The CoG issues were regarded as insurmountable until larger tail surfaces arrived with the Mark VIII and later-production Mark IX's. This is a bit suprising as the Mark V rear-fuselage ferry tank carried 29 gallons, while flight testing of a Mark IX with the 75 gallon rear-fuselage tank indicated that the lateral instability associated with the extra tankage eased considerably after 35 gallons had been used, taking the remaining capacity close to the earlier 29 gallon tank level. This of course is a comment made in ignorance of the physical positioning of the tank, which would have the biggest impact on the CoG and consequent stability of any one factor. -------------------------------------------------------- You may recognize the poster's style, although he's since undergone a revolutionary reincarnation ;-) snip The Mustang could only retain a fraction (ca. 25-50%) of that rear tank fuel to use for combat without being dangerously unstable, with the contemporary Spit possibly (probably?) being unable to retain any of it; Actually, the relevant testing in January 1945 revealed that the acceptable manoevering limit with the 75-gallon rear fuselage tank was 9.9 inches aft of the datum, or after 34 gallons had been used. Clearly the tank didn't need to be emptied for this to be achieved. at best, it could retain the same fraction as the Mustang. The Mustang with rear tank didn't have 269 U.S. gallons to fight and return on; it had somewhere between 205 and 227, depending on what fraction of the aft tank capacity allowed acceptable combat handling. In this case we have a Mk IX with 85 gallons internal forward tanks and about 40 gallons in the rear tank within apparently tolerable limits for combat. With which tail, and did the a/c have leading edge tanks? To be an acceptable long-range escort, the Spit still needed the extra forward fuselage fuel of the later Mk. IXs and the Mk. VIIIs, plus the leading edge tanks of the latter. The Mk. VIII carried 124 Imperial gallons internally (149 U.S), ALL of which was usable in combat, plus whatever extra fuel usable in combat (if any) a rear tank provided. Ah, here we disagree: as far as I know, most IX/XVIs didn't have enlarged forward tanks (in the traditional position forward of the cabin bulkhead, behind the engine), and most MK VIIIs seem to have been similar. So the best reliable figure for the internal capacity of the Mk VIII would actually be around 110 Imp galls. I suppose Air Commodore Alcala, Director of Fighter Operations in this scenario, will be pressing the Air Member for Research and Development to get them all with the enlarged forward tanks as well.... Every source I have implies or claims that all Mk. VIIIs had the bigger forward fuselage tanks, but I'm willing to be convinced otherwise. But the tank size increase, according to a different poster from a couple of years ago, was something that could be done on any Mk. VIII or IX -- the space was always there, it just hadn't been used. Oddly enough, http://www.fourthfightergroup.com/ea...9tactical.html which contains the tctical trial data for AB 505 from April 1942, (i.e. prior to the testing of AB 197, which had the usual 85 gal.), states that "25......... The fuel capacity of the Spitfire IX is 92 gallons, 57 in the top tank and 35 in the bottom tank. This is 10 gallons more than the Spitfire VC." [increased tankage of 2 Spits IXs from Wright Field, July 1944] In the case of the Spit wing it seems to have been a strength issue, at least according to Quill Yes, but I suggest what Wright Field did was a reliable indicator of what the USAAF would have done if Spitfire production and procurement was within their grasp. A&AEE whinges about instability would get short shrift in this situation. Oh, I don't know. They found it impossible to increase the tankage of the P-39/P-63 for Cg reasons, and those a/c certainly could have used it in our service (it didn't matter to the Russians, but that was due to local theater conditions). . So I suggest basic experience of rear-fuselage tankage, and measures to combat the worst CoG issues resulting were at hand in plenty of time to have an impact on the postulated fitting of rear-fuselage tanks in the summer of 1943. The difference being that the flights to Gibraltar were ferry flights, and no formation maneuvering or combat flying with the aft tanks full was required. Sure, but how different is this from Vcs emptying them on the climb out of East Anglia and the cruise out to Holland? The short-ranged Spit Vs and IXs could handle combat in those areas, while the LR Spits would be briefed to pick up their escorts further out over the Zuider Zee. Giving them an extra 30-45 minutes of flight on internal fuel, even with the most restricted utility (e.g. only on the way in, no combat endurance to remain after entering combat) is still of use, and reflects the utility of giving them drop-tanks to start with. The final determinant is the distance over enemy territory a Vc could return on forward tanks alone after exhausting the rear tank, dropping the 90-gallon drop-tank and spending 10 minutes at high throttle settings in combat. This is obviously *not* a profile which makes it contender for deep-penetration escort, but it still means they should be able to operate out across Holland beyond Amsterdam and up to the German border. Even a marginal improvement like this would have had a real and clearly-observable benefit in supressing bomber losses. If the fuel in the external drop tank(s) is already roughly equal to the internal capacity needed to return, as it was with the 90 gal. tank, adding extra internal fuel that can't be used in combat does nothing for the combat radius, which is what we're interested in. Zemke makes this point with regard to the carriage of 2 x 108 USG tanks on P-47s prior to the D-25 models. All the earlier versions had 305 USG internal, and the switch from a single CL 150 (nominal) USG tank to a pair of 108s did little or nothing to extend the radius, although it did boost the endurance in the same area. zemek says that average fuel burn on escort missions was around 200 gal./hr., giving them at most about 90 minutes on internal fuel (this is with some combat allowance). Only when the D-25 and subsequent models entered service with the 65 gallon rear fuselage tank did the extra external fuel give an increased radius. Presumably most of this 65 gallons was usuable within Cg limits. Since it took quite a while for them to replace all the earlier models, even in the 56th, the extra radius couldn't be used for a long time. In the end, even the RAF cleared the rear-fuselage tanks for production usage in 1945, and they were happy enough to fit half of the tankage in the FR XIV and the full thing in the XVIII. Again, both a/c with cut-down rear fuselages. Yes, but the cut-down fuselage doesn't seem to be a factor in deciding whether a Spit got rear-fuselage tanks or not: the IX and XVI with conventional fuselage got them, the FR XIV got them and I suspect the XIV would have got them if it hadn't been succeeded on the production lines by the XVIII in 1945, which only came in a cut-down fuselage version. As it was, the example of the FR XIV and the IX/XVI indicates the cut-down fuselage actually had a lower capacity for rear-fuselage tankage (66 vs 75 gallons). See the two-year old post above, which indicates measures to move the fuel and Cg forward on these a/c. Getting to our respective readings and conclusions on Quill, I note that he says in the case of the Mk. 21 that he disagreed with A&AEE on whether the Mk. 21's handling was acceptable at a certain point, and that he felt that such handling deficiencies could be accepted to get an a/c with superior performance into the field (he's also man enough to admit that he may have been overconfident by this point that average squadron pilots wouldn't have had serious difficulties, based on his own skills). I suspect A&AEE were right on that point; but it's instructive to see, yet again, that Quill states a fix for the stability and trimming issues that plagued the F.21 in 1944 was known about (enlarged tail surfaces), but production issues ruled it out until 1945. Take the MAP monkey off Supermarine's back, demanding production at the expense of development all the time, and this and a lot of other relevant problems could have been dealt with earlier. Certainly what we intended to do, with range extension pushed to priority one. Would you happen to know what the production of Mk. VIIIs was in say October through Dec. '43, or maybe Jan. '44, inclusive? I'm thinking that a move like Arnold's (he gave the ETO _all_ P-38 and P-51 production for a three month period in late '43), giving Fighter Command all the Mk. VIII production in that period, would be enough to get us going. The MTO and everyone else will just have to accept Mk. VC Trops and/or Mk. IXs for a while longer (they were already using them in any case). Now, it may just be a question of him not thinking to mention it, or the way he worded it, but he maentions no such disagreement between himself and A&AEE regarding the handling of the rear fuselage tank-equipped a/c; he just says that the handling wasn't acceptable for a long time, and required a lot of development. The origin of the "acceptability" comments over the rear-tank tests appears to be Supermarine's development testing. Aircraft would only go to A&AEE after they had arrived at what they saw as a production standard (e.g. Quill testing the 75 gall RF tank in July 1944, but Boscombe Down not getting it for another six months). Also, note that the A&AEE testing was not a peacetime acceptance test as such - the aircraft and fittings involved were often ordered into production anyway to minimise delays to production totals, and A&AEE testing was often being performed as representative of current or imminent production. F.21's were actually being produced before and after A&AEE first critically reported on them. And Quill mentions that the F.21 a/c which A&AEE finally accepted had its handling much improved over the original version he was trying to get them to accept. I'm certainly not going to claim, based on such flimsy evidence, that this is definitive proof that the a/c couldn't have been flown in operations with an aft tank with accceptable handling much earlier given sufficient motivation, especially given your comments re the prevailing attitude of the A&AEE. But I do think it at least suggests that the Cg problems were real and agreed to be so by both the A&AEE _and_ Quill. And that's as far as I'm prepared to gaze into my crystal ball. Your reading may well be different. And it is, I'm afraid. A&AEE seem to get their first rear-tank Spit in January 1945, and quantify it as acceptable once 34 gallons out of the 75 were used. Nobody was going to Boscombe Down and pushing this idea, the whole issue seems to come from Supermarine. Posit a burning interest in the Air Ministry in increasing inernal tankage in 1943 (e.g. ACM Kramer getting upset) and I suspect things would have been remarkably different. Pete and I certainly hoped that would be the case, although I don't know that the rear tankage was critical. As long as we could get standard Mk. VIIIs (or LE-tank Mk. IXs) for the initial day transition period (France/Low countries/Ruhr/German coastal targets), if the Spit aft tank was taking too long Mustang production would probably cover our needs (as well as those of the U.S.) by the time we were ready to go deep. And then we'd be on the continent, and it would become almost a non-issue. snip then either expanding Mk. VIII production at the cost of the Mk. IX That would have been possible, but only at the point of converting Castle Bromwich over to the VIII in the summer or autumn of 1943. This needs a demonstration of the effectiveness and need for it somewhat earlier: hence my LR Vs in 12 Group in July. See Pete's post Mk. V Cg range. or (if possible) transitioning to Mk. IXs with the extra leading edge tanks of the VIII, with aft fuselage tanks and whatever airframe mods required to pack usable _combat_ fuel in. That would have required prducing the VIII wings & airframe, I believe, rather than stuffing a Merlin 60-series into a Vc airframe as was done to churn out IXs. So I think there would be production infrastructure issues. As it was, the Supermarine production group around Eastleigh delivered about 90 Mk VIIIs to the RAF in July 1943, which should be enough to prove the concept if you grab them all. That's what we want, say 6 squadrons worth of Mk. VIIIs to start with. Sure, and that with an aft tank was next on the agenda after boosting production of the standard Mk. VIII/leading-edge tank Mk. IX. Either of the latter should have given us an escort radius of 250-300 miles. See my note on the actual forward-tank capacity of most VIIIs. Although this may have been changeable. And see my comments. Unfortunately, a similar chart for a Mk. V doesn't seem to be available on the site, but I have my doubts that the Mk. V was carrying around any such ballast in 1943, or if it did, so far aft. Of course, AB197 was a very early Spit IX (the report date seems to be June 10th, 1942), so that ballast was probably reduced as more operational equipment was added, but it at least suggests (combined with the Mk. V's further aft Cg vs.the Mk. IX as reported in various tests on the site) that the Mk. V was pretty much at the limit, while the Mk. IX had considerably more Cg range available. I can't find anything to substantiate this with the V myself, and I understand the validity of your reservations. Nevertheless, the critical issue as I see it is whether any rear tankage could become available given improvements in the CoG by means of the enlarged elevator horn balance and convex Westland elevator. I fully accept this would, in all probability, have been insufficient to allow a 75 gallon rear-fuselage tank to be carried and cleared for combat. The critical issue is whether this would have been enough to permit a rear-fuselage tank to be used in the early stages of flight to extend the pre-combat range. Given that this was done with a 29 gallon rear tank, I think there is a useable margin, albeit a smaller one than a LR-fitted Mk VIII with better weight distrubution and enlarged tail surfaces would have. See Pete's post, which seems to confirm my reservations. I'm focusing on using the V not because it had more or even comparitive utility with the Alacal/Stickney LR Mk VIII (something I've argued for in the past myself), but because even with the greater constraints involved, it was a more likely concept-demonstrator in the historical timescale. If you want an overnight conversion to LR Spit IXs at any given point without the example of a LR operational trial in the RAF to start with, you'd have to posit the removal of most of the higher command and their staff involved to eliminate their existing preconceptions and prejudices. Well, we're already postulating that Winston has tossed most of the CBO out the window and told Butch to knock off most of the area bombing and switch to days, so existing prejudices have already been overturned. There'd still likely be a rearguard action, but it would be difficult to sustain when those 'action this day' prayers start being delivered to Portal on down. So this is why I think LR Vs would be an issue worth consideration even taking into account their inferiority from all aspects of the job when compared to the VIII. I think it's more credible to posit changes in the Vs proving the concept, as this would be more institutionally tolerable. This is important from my point of view, as I think any counter-factual speculation has to be made within the known constraints of the industrial, economic and institutional context to remain credible. I accept the idea, but retain my caveats over Cg, now strengthened by Pete's comments. [production pressures] I don't underestimate the pressures, I just think (as you mentioned a few paragraphs above) that if the decision had been made to go over to daylight, fighter range extension would have increased in priority and changes would have to have been accepted, whatever the disruption elsewhere. Because otherwise, it wasn't going to work. Indeed, but when the RAF actually faced this dilemma, at the end of 1939 and then again in spring 1941, they abandoned daylight bombing. The two concepts had become divorced, for understandable external reasons, and asserting a sudden and complete reversal of this is stretching the credibiluity of the institutional appreciation involved in the speculation. Now I think the concept is possible, and a valid piece of historical speculation, but I also think it has to work within the context involved, and, frankly, anybody demanding a reduction in Spitfire production in favour of speculative operational development was on a losing wicket. The British strategical position in this respect can't be overstressed too much: the USAAF had a doctine and institutional ambition towards independence which was served by the 8th AF campaign, secured by other forces doing things like protecting their bases and dealing with the existing war against Germany. They had room to stop and rethink tactics and strategy, and change production priorities accordingly. The British did not have this space. They had to maintain existing commitments and fight the war as it existed from a smaller industrial and economic base closer to the enemy threat. Proving strategic concepts, even ones which had great war-winning potential, was a luxury that could not come at the expense of the means for repelling the enemy in the meantime. The RAF could not prejudice production of their main fighter when it was needed for home defence, operations in the MTO and Far East and supply to the Russians. The difference between these commitments and facilitating daylight strategic bombing was the difference between fighting the war and demonstrating an abstract concept. Whatever happened in the skies over Germany, Fighter Command were conceiveably in a position to lose a war for national survival. The 8th AF wasn't. No lack of respect intended. The 8th might prove vital in winning the war, but high Spitfire production was known to be needed meanwhile to avoid defeat and stay in the war, which was an essential prerequisite. I don't agree that was the case by mid '43. Under no conceivable set of circumstances could Fighter Command lose air superiority over the UK then. As it was, Fighter Command was over-manned and equipped, and as you have yourself stated, under-utilized. What happened in Burma and in the Italian campaign weren't going to decide the war, and the Russians could have survived quite well without Spitfires. If nothing else, we could have produced more P-39s/P-63s, which in any case were etter suited to conditions on that front. snip areas of agreement or mild disagreement Please desist from this moderate rationality or I will complain to your ISP. Did I mention that I have INCONTROVERTIBLE PROOF that the U.K. government has been testing UFOs ( and dissecting ALIEN CORPSES) at their base at Machrihanish, Nah, you're just confusing Alien corpses with the average westie. Understandable mistake. We only retain them to give the midges a round-the-year locally-available food supply until the German tourists appear in the summer. cleverly disguising test flights of same as those by Aurora and, in times past, SR-71s? Wait, I hear the black helicopters coming to get me. I can feel the beams as they try to alter my brain. Excuse me while I done my tinfoil hat. Interesting theory, although it lacks credibility, until we acknowledge the critical role played by the Templars and the Illuminatii in the Ministry of Aircraft Production in 1942 [censored] That would explain the Templars' intimate knowledge of Spitfire fuel tankage, as reposted well above ;-) Guy
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