Sublime Posted November 17, 2019 Posted November 17, 2019 Apparently you cant have both. (Disclainer I love convos and will shameleas start debate if allowed) What do youse do and why? I wont lie. I havent even flown the 150 spit yet! I will now though. Dies the merlin 70 matter anymore or was it good for the time until 150 octane was aroubd?
ShamrockOneFive Posted November 17, 2019 Posted November 17, 2019 The Spitfire IX series had a number of different engines across it's lifespan. For the purposes of simplifying things, in the late war period of 1944 and 1945 there were two engines most typically used. The Merlin 66 was the "low altitude" engine and the Merlin 70 was the "high altitude" engine. Spitfire's equipped with the Merlin 66 were officially marked as Spitfire LF.IX and those with the Merlin 70 were HF.IX. The LF and HF designation in some books are confused with the types of wing fitted but that is incorrect and pertains strictly to the engine. The Merlin 70 and the Merlin 66 are essentially the same engine but with different gearing on the supercharger and that means that the second stage supercharger (kind of like gearing on your car) kicks in at a higher altitude. It means that the Merlin 70 generates more power at higher altitudes and gets it's best speed at over 1650 meters higher and almost 13km/h faster. A medium and lower altitudes the Merlin 66 equipped Spitfire is faster. The 150 octane fuel is only available on the Merlin 66 because it is at low altitude where the added octane will make the biggest difference. 4 2 2
G_Schwarz Posted November 17, 2019 Posted November 17, 2019 28 minutes ago, ShamrockOneFive said: The Spitfire IX series had a number of different engines across it's lifespan. For the purposes of simplifying things, in the late war period of 1944 and 1945 there were two engines most typically used. The Merlin 66 was the "low altitude" engine and the Merlin 70 was the "high altitude" engine. Spitfire's equipped with the Merlin 66 were officially marked as Spitfire LF.IX and those with the Merlin 70 were HF.IX. The LF and HF designation in some books are confused with the types of wing fitted but that is incorrect and pertains strictly to the engine. The Merlin 70 and the Merlin 66 are essentially the same engine but with different gearing on the supercharger and that means that the second stage supercharger (kind of like gearing on your car) kicks in at a higher altitude. It means that the Merlin 70 generates more power at higher altitudes and gets it's best speed at over 1650 meters higher and almost 13km/h faster. A medium and lower altitudes the Merlin 66 equipped Spitfire is faster. The 150 octane fuel is only available on the Merlin 66 because it is at low altitude where the added octane will make the biggest difference. just want to add that if you use the 150oct you would have to switch the supercharger gears buy your self the auto switch is not there
Sublime Posted November 17, 2019 Author Posted November 17, 2019 59 minutes ago, ShamrockOneFive said: The Spitfire IX series had a number of different engines across it's lifespan. For the purposes of simplifying things, in the late war period of 1944 and 1945 there were two engines most typically used. The Merlin 66 was the "low altitude" engine and the Merlin 70 was the "high altitude" engine. Spitfire's equipped with the Merlin 66 were officially marked as Spitfire LF.IX and those with the Merlin 70 were HF.IX. The LF and HF designation in some books are confused with the types of wing fitted but that is incorrect and pertains strictly to the engine. The Merlin 70 and the Merlin 66 are essentially the same engine but with different gearing on the supercharger and that means that the second stage supercharger (kind of like gearing on your car) kicks in at a higher altitude. It means that the Merlin 70 generates more power at higher altitudes and gets it's best speed at over 1650 meters higher and almost 13km/h faster. A medium and lower altitudes the Merlin 66 equipped Spitfire is faster. The 150 octane fuel is only available on the Merlin 66 because it is at low altitude where the added octane will make the biggest difference. Thank you. I had no idea but i figured somehow the fuel must ve even better low or somethkng because most il2 happens low so I always tried ditching tbe merlin 70 1 hour ago, ShamrockOneFive said: The Spitfire IX series had a number of different engines across it's lifespan. For the purposes of simplifying things, in the late war period of 1944 and 1945 there were two engines most typically used. The Merlin 66 was the "low altitude" engine and the Merlin 70 was the "high altitude" engine. Spitfire's equipped with the Merlin 66 were officially marked as Spitfire LF.IX and those with the Merlin 70 were HF.IX. The LF and HF designation in some books are confused with the types of wing fitted but that is incorrect and pertains strictly to the engine. The Merlin 70 and the Merlin 66 are essentially the same engine but with different gearing on the supercharger and that means that the second stage supercharger (kind of like gearing on your car) kicks in at a higher altitude. It means that the Merlin 70 generates more power at higher altitudes and gets it's best speed at over 1650 meters higher and almost 13km/h faster. A medium and lower altitudes the Merlin 66 equipped Spitfire is faster. The 150 octane fuel is only available on the Merlin 66 because it is at low altitude where the added octane will make the biggest difference. And thank you as well
FeuerFliegen Posted November 21, 2019 Posted November 21, 2019 Any idea what 150oct vs Merlin 70 performance is at high altitudes?
Talon_ Posted November 21, 2019 Posted November 21, 2019 On 11/17/2019 at 6:50 PM, ShamrockOneFive said: The 150 octane fuel is only available on the Merlin 66 because it is at low altitude where the added octane will make the biggest difference. The Merlin 70 was also rated for 150 octane fuel +25lbs boost however there's not enough data to model it in-game. 1
JtD Posted November 21, 2019 Posted November 21, 2019 What data is missing? I find it hard to believe that this would actually be the main reason to not model it. Even if no data at all existed things can be extrapolated and/or taken over from the very similar Merlin66. I know clearance existed, but I have no clue if and if so to what degree it actually was used in service? Wasn't it mostly the 2nd TAF which was mostly equipped with LF models? Maybe the 8th with their 51's with -3 Packard Merlins?
CountZero Posted November 21, 2019 Posted November 21, 2019 6 hours ago, FeuerFliegen said: Any idea what 150oct vs Merlin 70 performance is at high altitudes? Red is m70 max speed, blue is m66 with +25lbs mod max speed 1
Kurfurst Posted November 21, 2019 Posted November 21, 2019 1 hour ago, JtD said: I know clearance existed, but I have no clue if and if so to what degree it actually was used in service? Wasn't it mostly the 2nd TAF which was mostly equipped with LF models? Maybe the 8th with their 51's with -3 Packard Merlins? IIRC the clearance was +21 lbs for the Merlin 70, but its highly theoretical as it is rather doubtful if it ever used it, even for operational trials. No known records of it. For the entire duration of 1944, there were but two 150 grade Merlin 66 IX LF Squadrons (Nos. 1 and 165) doing operational trials, posted far from the action and generally just gathering experience and live testing if the fuel is feasible for operational use at all. All of those were Merlin 66 and none of the planes had Merlin 70 and there is no known use for increased boosts in the Merlin 70 at all, even for trials, though I suppose RR itself may have tried it on the bench. Add to that that there were just 2 or maybe 3 Squadrons operating with Merlin 70 IXs during the whole war, and all based in Britain. These were special high altitude Squadrons, and had no use for boosts feasible for lower altitudes to start with. No Merlin 70 Spit squadron with the 2nd TAF at all. All of them Merlin engined ones were Merlin 66/266 L.F.s. So the real question regarding the M70 engine mod is not why doesn't have a 150 grade option, but rather - why is the M70 is in the game at all. No 2nd TAF Squadron ever had them, even of those that stayed in Britain were very few in numbers. I suppose they are in because it was an easy way around not having a XIV. 4
BlitzPig_EL Posted November 21, 2019 Posted November 21, 2019 By the same logic you could argue why we have the Bf109K4 1.98 at all, as their numbers were so few as to be inconsequential. 1 1
Kurfurst Posted November 21, 2019 Posted November 21, 2019 15 minutes ago, BlitzPig_EL said: By the same logic you could argue why we have the Bf109K4 1.98 at all, as their numbers were so few as to be inconsequential. That has been argued many times, and was shown incorrect IMO with nada evidence presented to support theory. And why reiterate the same arguments in the wrong thread. 3
Talon_ Posted November 21, 2019 Posted November 21, 2019 42 minutes ago, VO101Kurfurst said: IIRC the clearance was +21 lbs for the Merlin 70, but its highly theoretical as it is rather doubtful if it ever used it, even for operational trials. No known records of it. You don't RC at all
Kurfurst Posted November 21, 2019 Posted November 21, 2019 Actually you are half right, service approval for +25 was not given for the Merlin 70 until 31st January 1945, and amendments has yet to be made. From which it follows that prior to the approval in 1945, it wasn't +25. It was +21, see the RR operational warning card design from 24 May 1944. At least theoretically, since both No. 1 and No. 165 Squadrons which tested 150 grade for suitability only had Merlin 66 Spits... And as for the 'evidence' for it's performance is a home drawn estimate on a chart in which Mike Williams himselfs 'extrapolates' performance from +18 lbs trial results on HF IX protos tested in 1943... there are not even factory estimates, even less actual tests.
JtD Posted November 21, 2019 Posted November 21, 2019 (edited) 17 minutes ago, Talon_ said: Spitfire IX HF level speed performance See, wwiiaircraftperformance can extrapolate Merlin 70 data, why can't the devs do the same? "No data" is no reason to not include it, so the reason is something else. 1 minute ago, VO101Kurfurst said: It was +21, see the RR operational warning card design from 24 May 1944. That's a Merlin 72/73, which weren't cleared for anything above 21lb. Wrong card perhaps? Edited November 21, 2019 by JtD
Recommended Posts