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#161
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Peter Stickney wrote:
In article , (The Revolution Will Not Be Televised) writes: snip Whatever happened, the tanks were going to be jettisoned before initiating combat, so I don't think the 90 gallon tanks - which should be substantially emptied and consequently lighter before the aircraft got to the prospective combat area anyway - would in those circumstances impose as much of a performance restriction as we might suppose. True - I was thinking in terms of a way to add 90 gallons to a Mk V's fuel capacity (Which would be about 50% of total fuel anyway) withoug the stability and drag penalties that the 90 gallon tanks imposed. (It's not much good being an escort fighter if you cruise slower than the bombers that you're escorting.) To my ming, 29-30 gallons internal, with another 60 or so external would about do it, especially if the 60 gallon tank has no restrictions. Pete, the drag penalty of the 90 gallon tank wasn't all that much. It knocked about 20 mph off the Spit XIV's top and max. cruise speeds, and less than 18 mph (337.5 vice 354) off the top speed of a Mk. VC Trop, AB 320, that A&AEE tested; go here for the full report on level and climb performance with and without the tank: http://www.fourthfightergroup.com/eagles/ab320.html A Mk. VIII/IX would presumably take a speed hit in between the two, given that it's faster than the Mk. V and slower than the Mk. XIV. In short, not significant, and there's absolutely no danger of cruising "slower than the bombers that you're escorting." WITH the tank, the Spit XIV was still faster than the Me-109 or FW-190A. The Mk. IX wouldn't be, but would still be able to cruise at 300TAS or higher at the heights of interest with no problem. Remember, I'm not asserting that any of this was an optimal solution for long-range escorting, or could have competed with aircraft that were better suited to expanding their internal fuel capacity. I'm trying to work along the lines that would be dictated by operational neccessity and addressed with existing equipment and experience in certain circumstances. Well, in htat case, gin up a 60 gallon tank, and add teh 2 13-gallon leadig edge tanks. The 80 gallon tank would give you about 40% of teh total fuel, allowing it to be empty before the target area is reached, and the 13 gallon tanks can be swapped in as a Deport-level job. They fit in the leading edge outboard of the 20mm gun bays. but inboard of the .303s, and slotted in between a pair of ribs. That sort of sheet-metal work would be well within what they could do withoug a need fr a factory-level rebuild. Again, I'll raise a practical objection to installing tanks outboard of the guns (any guns): where are you going to route the tank piping? You can't route it through a gun bay (well, you could, if you didn't mind the constant danger of broken fuel pipes owing to vibration loads when shooting, not to mention the danger of fires -- I can't see even the most clueless RAF type signing off on this), and there's really not a whole lot of room in the wing aft of the cannon bay (but forward of the flaps/ailerons and their actuators) to pass them, even assuming that you're willing to make a couple of 90 degree or so bends in the piping to do so. This is an interim mod until the RAF's Mustangs become available, so it needs to be something that's already been done, and that's the Mk. VIII tank installation, with maybe an aft tank added if the Cg is okay for combat (and the max. gross weight isn't exceeded when also carrying a 90 gal. or larger drop tank). Guy |
#162
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The Revolution Will Not Be Televised wrote:
On Wed, 24 Sep 2003 09:16:49 GMT, Guy Alcala wrote: The Stirling III and Halifax III still seem to have a major differential in terms of operational ceiling, which I can only put down to structure weight and the wing. snip A better operational ceiling comparison would be between the Stirling III and Halifax II, as the latter has the original 98(?) foot wing (some sources claim that early Halifax IIIs had the original wing; I don't have enough info to say). The Halifax II is still better but not much, and I expect the difference is largely due to the lower weight, and maybe the drag of the Stirling's nose turret. [quick driveby] I sure hope not. I had enough experience with those living in East Oakland in the early '80s (per capita murder capital of the U.S. for several years). OTOH, they had generally execrable aim, which made the intended targets relatively safe but put the innocent bystanders at risk. The closest one I was exposed to was at a distance of about 50 feet, but fortunately the shooter was facing away from me and firing into a non-moving car with two guys sitting in it, so there was little chance of me getting hit by the odd round. He and his homeys pulled up in a stolen van, he jumped out the side door and opened fire, but only managed to crease one guy in the arm and IIRR the other got hit by some flying glass from one of the windows. I later counted only nine rounds that hit the car (semi-auto machine pistol of unknown type, fired from the hip), distributed all over it (two just creased the roof), from a distance of about 5 ft. Pathetic aim, especially considering that these guys were likely to return the favor. And all because the shooter's sister had taken offense at something one of the guys in the car had said to her an hour or two earlier. The early Halifax II's (i.e. those produced throughout 1941-42) had the Mk I nose turret, and clocked in at 34,980 lbs with an auw of 60,000lbs with a 98 ft 8in wingspan. The Stirling III seemed to come in at something like 42,000lbs with auw's somewhere over 60,000lbs (figures I have vary between 61,000 and up to 70,000lbs), so there's a couple of tons of weight difference before the operational load gets included. I've often wondered at that 42,000 lb. figure, but I think Geoffrey provided some numbers earlier in the thread. The Stirling Mk III couldn't get above 17,000 feet (a couple of thousand feet below routine operational heights for the Halifax), and had a lower rate of climb than the Halifax. Early Halifax Mk IIIs did have the shorter-span wings before they got the extended 103 ft 8in wingspan. So I'd like to know how high the Halifax IIIs could operate with the short wings. Guy |
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