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JtD

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  1. Yeah, gear down is pretty sh*tty aerodynamicwise, and while it might be possible to score a 20mm hit that has a similar effect, as a standard it shouldn't (on aluminium skinned aircraft). Ballpark: If you were to assume a speed drop from 600 to 474 km/h CAS and a 1200kW engine (at prop), you'd have created about 4000N of extra drag. Dynamic pressure at 474 means that you'd need about half a square meter cross section minimum to create that kind of drag (you'd need to stop the air dead over that cross section). A wing with a thickness of say 0.3 meters would thus need a about 1.5 m damage spanwise in order to achieve this, which is about 5-10 times of what you typically get from 20mm HE.
  2. For instance on the site you quoted from. http://www.wwiiaircraftperformance.org/tempest/tempest-V.html Near the bottom of the page are Tempest V data sheets, both of which state 150rpg.
  3. The Germans classified their noze fuzes as instantaneous, but the description include a delay mechanism to "make sure the shells goes off inside". This is how they manage the half meter. Real instantaneous fuzes will be a somewhat faster. But since the all are based on mechanical and/or chemical reactions, they don't work at the speed of light. I don't think your 170 micro seconds is far off.
  4. Well, they say that one trigger fires all guns, but actually you could still fire the guns separately or together by manipulating the switches and fuses in the electrical equipment. I think the wording in the English translation of the Russian report of the test of the German aircraft is somewhat misleading, but in a literal sense it is true. Is there a reason to not fire them all together? In particular in that stage of the war? FWIW, in the Fw190 series it always was fuselage guns + wing root guns in one group and wing guns, if installed, in a separate group. So they just kept the design they had been using for years already.
  5. How do you know the anecdotes are not related to the D-9? The author of the statement used "KG" and has since made clear he doesn't distinguish between different engine management units. I'm fairly certain he knows what he meant to say and unless you're a powerful psychic, you don't. Why do you keep telling him what he knows and meant to say? OTOH I'd appreciate some more actual information, so if you have some to share, that's the road to go down.
  6. WRT to the responsiveness of the Jumo213, the prop needed about 8 seconds to go from operating rpm to fully feathered, when the engine was dead and an auxiliary hydraulic pump with a much lower capacity was used. In game, we have about the same figure, but in normal operation. Unfortunately I don't know the exact capacity of the auxiliary pump, so I can't estimate how much faster the ptich adjustment should be with the main pump doing the hydraulics.
  7. Yep, I'm sure the British tested guns and ammo they didn't use in combat and instead of a controlled environment at a shooting range they'd field test it using entire aircraft installations and when they said from directly behind they mean something else. Makes sense. Just as a reminder - Nazgul was of the opinion that no aircraft skin or WW2 pilot armour would stop a .50 AP. I merely provided an example where this is possible, as some food for thought. Consider it or ignore it, your choice. I don't really care.
  8. Ballistic tests. And you don't need to defeat an armour plate, you need to defeat the entire pilot protection which starts, as I stated already, with the aircraft skin.
  9. Yet, the pilot protection of the Fw190 from dead 6 attacks was sufficient against 0.50 rounds. Main point, besides internal components, is the shallow angle of impact on the alumnium aircraft skin prior to hitting the armour plates, having a bad effect on the ballistics. Tests condcuted showed that the pilot would be safe in that kind of attack (at least from direct hits by AP rounds). Fw190 armour was hardly top of the line, other aircraft carried better protection.
  10. No, it is not. All true air speeds (TAS) are being calculated from indicated air speeds and other properties. The calculation is just different (more complex) if you want to correct for compressibility. You can see both formulas on the sheet Karaya linked. The basic procedure was to calibrate the speed indicator at low altitude over a test course marked and measured over ground. You measure time on the ground (or/and in the air) between start and end point, you'd record indicated speed, temperature and pressure (and maybe other quantities if you needed to be more accurate). Knowing true air speed from the ground measurements and indicated air speed as well as atmospheric conditions, you'd use that to calculate position error of the speed indicator, giving you a chance to arrive at calibrated air speeds for the indicator used. You could then go on to measure indicated speeds at different altitudes and test scenarios, while still recording pressure and temperature, so you could calculate your true air speeds at altitude from converting the IAS to CAS using the position error determined earlier and from that you would calculate TAS using the recorded atmospheric properties. Either with correction for compressibility, or not. But you'd always calculate. You'd then would also calculate additional corrections to arrive at a defined standard condition of the aircraft, say full take off weight, which you don't actually have in the flight test. Weight, for instance, is constantly changing. Outside of this, performance figures marked as "berechnet" (calculated) often refer to figures not (yet) backed up (sufficiently) by flight testing. They did calculate a lot back then, even without computers. It would look like this (part of a climb calculation for the A-9). You could arrive at best climb speeds and certain climb performances, but until they were tested and confirmed, they'd be marked as "berechnet", in particular when compared to flight test confimred data (of say previous models). Yes, they certainly did. Otherwise they wouldn't know what difference it makes and would never arrive at the conclusion to use the more accurate calculation. Interestingly enough, the 656 from the A-5 in this calculation also found their way into some official performance figures, even though it was stated that figures for A-8 and earlier all come without correction. OTOH, the A-5 aircraft data sheet for instance gives 680 km/h, without correction. Even there it's not as binary as I remembered it to be.
  11. Because it came up - several of the historical performance figures are also derived from treating CAS as EAS, meaning they ignore compressibility and give too high speeds at altitude. For instance, all speed performance figures for the Fw190 up to the A-8 are given without taking compressibility into account (thus are too high), while figures for the A-9 and later take compressibility into account (thus are correct). Fw only changed that in 1944. I don't think I have seen a similiarly definitive statement for the Bf109 anywhere, but we can be pretty sure that not everything that Messerschmitt or the Luftwaffe tested is always spot on. Best I know - there's a Messerschmitt test report from September 1942 that mentions the transition, so it shouldn't be an issue with the G-14, we just can't be 100% sure.
  12. Early G models had speed indicators that only went to 750, and in German aircraft you don't get limits that are higher than the range of the instrument. Sounds ridiculous, but it's true - if the pilot doesn't know how fast he's going, he's not permitted to go there, case closed. So for early models this alone would be a limiting factor. Not sure when the indicator was changed (anyone?), but the K definitely had an indicator with a range up to 1000.
  13. All manual figures given for German aircraft are either calculated with a safety factor of 30% (I think that's dynamic pressure, but could be IAS directly) or flight tested to the point where flutter starts. Flutter is Mach-related, not IAS. So if you have a test where flutter starts at 0.77, that's one limit, but not related to IAS, and the other is manual speed down low, times square root 1.3 = 1.14 (or 1.3). So 850 is safe by design (could even be 975). Static load issues of Bf109 in dives were mostly related to pilots trimming nose up during the dive to counter a nose down pitch, only to shed wings when pulling out.
  14. All aircraft are modelled after tests and historical references of dive speeds (safely) obtained, not after the manual figures. In some cases, historically, manual figures may conincide with actual maximum (safe) performance, in most cases, actualy limits are higher than the manual limits.
  15. I don't think pilot physiology is effected by fuel and oil systems.
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