rel4y

The Merlin 66 weighs 748 kg at 27 l displacement, the Griffon 65 weighs 948 kg at 36.7 l displacement, The DB 605 D weighs 745 kg at 35.7 l displacement. I guess thats what they were trying to compare. The DB 605 D really is rather light, but doesnt have a carb nor intercooler for example. Makes perfect sense to me. The engine card of the DB 605 AM says btw it weighs 730 kg.

See for yourself. ;) These are all the P-51D tests I have access to. Edit: DCS currently models the 67" Hg based on the black line.

Well thats interesting. The german G-2 manual (March 43) says 4-6 strokes in cold weather conditions. Does it say something about the temperature for the finnish recommendations?

I read in a real pilot report (DB 605A) of priming 3 times. 20 strokes priming will likely flood the cylinders and is not a good idea in my oppinion. You also need to open the throttle a significant amount (~1/3rd) and as DefaultFace said hold the inertial clutch pressed long enough, then it usually works on the first try for me. The original Bf 109 E manual says 2-3 strokes priming, in cold weather conditions 4-5 strokes. For a warm engine only 1-2 strokes. This is for a DB 601, though from what I have read nothing changed to the later models.

Does happen to me as well since a few updates, but only concerning the MK108. Sometimes I wonder if it is even firing as I am pushing the button, then it suddenly sets in.

The slats are not spring loaded, it is pure aerodynamic forces that control their deployment. In combat turns the K4 drops wings at around 20° AoA, fits pretty well to the data. Maybe people should read about how slats work and how they retain directional stability up to the increased stall AoA. This kinda reminds me of the thread about two months ago where people complained the engine can sustain vertical prop hanging indefinitely. Then it turns out the plane really was doing 210 kph TAS, with both rads fully open and the engine still did overheat eventually... ED is really patient with some people, I wonder for how long.

I usually only prime 3 times. 20 sounds a bit excessive.

Works as intended. It takes some time to drain though. Half a year our longer ago I tested this way if the MW tank content has an effect on the planes cog and it did.

Climb speed was usually measured at 170 mph (~270 kph) up to around FTH. The K4 climb speed figures are usually for 260 -280 kph, while the Finns achieved better climb results at ~300 kph but with closed radiator. I would say there shouldn't be much difference. Higher up the spit should outclimb the 109 due to lower wingloading. This means climb advantage of the 109 diminishes with altitude.

The DCS K4 with MW50 does around 25 m/s at MSL. It looks rather like the following. The Dünnblattschraube only influences level speed, as seen in the high speed tests of the same document. If comparing 18 and 25 lbs boost for the spitfire one should be careful which test he looks at. There were several different test runs done with JL.165. The Hucknall one should not be cited as some sort of 160 octane fuel was used which never saw war service and we dont know the composition nor lean octane rating. The A&AEE test is much more significant as done with standard 150 octane wartime fuel, though also not fully in operational config, but very close. Especially the blanking plate will have significant influence. In relevance to the DCS spit level speed charts may look something like the red line. Mind this may be rather on the optimistic side, but good enough for an impression. See here an original doc for reference http://www.spitfireperformance.com/merlin66_18_25b.jpg. Looking at climb rate the expected change should look something like this, while the absolute values are a bit on the low side. The real values should look something in between this (at 18 lbs) and the BS 543 test, as for BS 543 again some changes were done such as sealed gun ports and using some weirdo prop. Also take a look at how the radiator settings influence climb rate, quite impressive (~2.5 m/s).

That is at least not in my focus. After sleeping a night about it I have to say that the current mod spit is veeeery unlikeley to the point of being implausible. Let me explain why. Since it sports the old style elevator it had to be produced before 13-9-43. That would have been maybe in the MH range of S/Ns, at latest at the end of the MH range all aircraft would be equipped with new type elevators from factory. Now while the DCS variant would have been initially fitted with the old short carburettor intake, the new carburettor intake would be introduced 29-12-43 but wasnt made retrospective - except if the part was damaged. That means sometime in 44 the aircraft must have had some sort of air intake damage so it got replaced with the new large style one. This could not have been done on site, but rather at MU maybe GSU level. The single cannon blister which the DCS variant shows was introduced 7-1-44, so again it must have been retrofit in 44. Also if the spit was to carry bombs, by mid 1944 the wheels would have been exchanged to the tougher 4 spoke wheels. Then there are the tire bulges which were introduced 10-44 and were not a common modification for previously produced aircraft but rather only seen on late produced factory state aircraft. Now to come back to the elevator. I actually today found out something which mad me switch my mind. As said, it was introduced 13-9-43 and there was actually a kit released which allowed for squadron based modification. That means the aircraft would not have had to go to MU or GSU to perform this type of mod. Now the tire bulges make the DCS spit at least October 1944, it had to have been in MU for the intake fit some time in 44, it had to have been for the tire bulges in at MU and it still flies around with the old elevator which was released even as a field based kit over a year earlier is absolutely implausible not to say impossible. So what are the consequences of this? I would say the new elevator is pretty much mandatory for this setup and I would recommend to get rid of the tire bulges. Then it would be a typical mid 44 LF Mk IXc. If keeping the tire bulges and bombs are modelled it would be recommended to model at least the new elevator and switch to the 4 spoke wheels. This would make it a somewhat believable late 44 LF Mk IXc ground support spitbomber. Though most likely it would have had e wing type/ armament. Not the perfect choice in my opinion. OK, that wraps it up for me on this topic. Now its EDs turn to decide.

What?! Real real life data confirms the overwhelming majority of all P-51s in WWII used 67 inches max and still pilots were not crying around. Theres two facts for you. As said innumerous times before you will be getting your 72 inches and I suspect that will change neither the relative performance of the P-51 nor your personal perception of inferiority. And yes the Spit will most likely perform better than the P-51 vs the german planes because it is just like them about a ton lighter than the invincible P-51 while having the same british designed engine.

That was supposed to be a joke, didn't quite work out I think. :D Main point is, it would be rather unlikely to see a c wing type spit with round (non kidney) tire bulges. I have so far only seen e wings with these blisters. But not impossible I guess.

Well not new ailerons but new rudder! ;) These blisters were necessary because by that time three separate stub axles could be fitted to the oleo strut to alter the caster and camber angles. This depended on the surface type from which the aircraft was operated.

Well the blister is in one regard relevant as only very late Mk. IXs had this type of blister. Actually I am fairly sure these blisters were introduced in October 1944. By that time, the elevator would - mark my words here - most probably have been exchanged with the elongated horn style elevator.

Well what has to be mentioned though is that the carburettor intake is not factory anymore, as the larger Vokes Aero Vee was standardized/ retrofit only in 44. Originally MH 434 had the small carburettor intake, so it is at least an overhauled 1944 version of MH 434. Looking at the service time of MH 434 this would probably have happened while being at 84GSU (15-6-44). 222S 13-8-43 shot down Fw190 9-43 84GSU 15-6-44 ros 7-7-44 76MU 27-7-46 Maybe the elevator wasnt changed in that overhaul/repair, I say we simply cant know if its correct or incorrect unless we have pictures with a certain setup for a certain timepoint. ED also may know more than we do in this regard.

I wouldnt say there is a correct or incorrect tbh.

I think you guys are absolutely right. :) Pretty much nothing is stock on MH 434 by now.

I know the discussion part of this topic has aged some time by now, but in the meantime I have discovered a few interesting facts about the tests discussed. I) The long carburettor intake fitted with the "universal" Vokes Aero-Vee filter was first introduced 29-12-43 and became more or less standard in 1944. (also includes retrofit) The filter was later in 44 fitted with the louvred plate. The level speed tests conducted by RAE with the louvred plate fitted (and blanked off) took place in October 44. The conclusions were as followed: The discussed graph can be found here: https://forums.eagle.ru/attachment.php?attachmentid=137453&d=1459196786 II) The SU injection carburettor was never fitted to any Mk. IX/ Merlin 66 engines besides some preliminary tests. Below is a list of which Merlin engine used which carburettor type. The SU injection carb increased FTH by ~1300 ft and gave and increased max level speed by ~5 mph. Merlin 61, 72, 73 used SU float carburettor Merlin 66, 67, 70, 71, 76, 77, 85 used Bendix injector carburettor Merlin 100, 104, 113, 114, 130, 131 used SU Injection carburettor This is only relevant concerning the MA.648 test. (http://www.spitfireperformance.com/ma648.html) The discussed graph can be found here: https://forums.eagle.ru/attachment.php?attachmentid=137094&d=1458838872 Over and out

Extended-horn elevators were introduced 13-9-43, serial nos having no bearing on which a/c had them, and which didn't

Well sure bendable, ground adjustable trim tabs are set before flight. That is kind of obvious from my text isnt it? The thing is, Yo-Yos reasoning for not including them was, why put in a secondary source of trim if there is already the stab. Well then why did the engineers include these trim tabs? Simply to give the pilot and it's ground crew another option to either personalize the aircraft to the pilot or to adjust for damage/ factory variation. I am pretty sure there is a technical reason to not include them, as the argument "you already have one option for pitch trim control" is invalid. As the second pitch trim control would allow to adjust the neutral trim point to the pilot liking within a certain envelope of course.

Hey guys! The graphs Yo-Yo used for balance behavior were from a NII VVS report of a Bf 109 G2/R6 (with gunpods) captured near Stalingrad and there is far as I know no 109 K-4 Ladeplan for exact CoG available at all. The main problems I still have with this approach is that the data is based on a captured and force landed G-2 with gunpods and we know nothing of how the ground adjustable trim tabs were setup for the test. I am still at a loss why no trim tabs for the elevator are added, as we can adjust rudder and aileron trim tabs in the options since many version ago. I find that to be very useful and have my ailerons set to -7 at all times. Even if the trim tabs in the VVS report are "assumed" neutral, then it should be viable for the pilot to trim the aircraft via the trim tabs to reduce the pitch up tendency in flight. I dont have access to my flight PC at the moment, but you guys could certainly check if the elevator response at 1.15° stab setting corresponds to the graph in the high speed dive trials. I have been citing this test for some time, as I find a much lower rudder authority in DCS than described.

Well it was an F with G wings and G rudder. So in terms of control surfaces it was identical to the Gs and Ks. I think there is a problem, because the test pilot describes how he could control the roll moment of the aircraft with the old horned rudder by aileron input. Furthermore the test pilot describes with the new tall rudder aileron input was possible but not necessary, which both contradicts current DCS behavior. Both at TAS way above 800 kph.

Yeah I have posted about this already some time ago in the bugs section. (https://forums.eagle.ru/showthread.php?t=170388) Funny thing is after the latest update all the control surfaces even break off at TAS 900 kph at 4 km altitude (ICAO standard conditions in ME). The document clearly states full controllability at these speeds in roll and in yaw after attachment of the new taller rudder. The K-4 even has a Flettner tab installed in the rudder which will reduce control forces further. Ill just add the graph again even though in the bug report I posted all important passages including the graph attached. Not sure why this behavior isnt being revised yet.

Well 67" was used by some planes over Normandy as well. So are you happy? Probably not. ;)