Messerschmitt at 5000 m

[Mangrove]

These are extracts from a study made by cadet Esa Tervonen on 19th May 1952, two years before the Bf-109s were removed from Finnish service. Finns used the "real" Bf-109 from 1943 to 1954, the last operational aeroplanes were type G-6. Finns didn't use their "Mersus" at full power so the HP readings aren't the same as the German.

MT:n nousu 5000 m:iin tapahtuu nopeesti johtuen koneen suuritehoisesta korkeusahtimella varustetusta moottorista. Nousu nopeudella 270 km/t on nousuaika vain n. 5 min 15 sek.

"The MT (Finnish designation for Bf-109) climbs quickly to 5000 meters due of the powerful supercharger installed to engine. Climbing with speed of 270 km/h it takes only around 5 minutes 15 seconds from 0 to 5000 m."

Maksimiteho koneella on siellä 1355 hv, suurin kestoteho on kuitenkin 1080 hv. Näistä luvuista huomaamme, että MT:llä on 5000 m:ssä parhaimmat lento-ominaisuutensa aina 5700 m:iin saakka. Vasta siitä yläspäin mentäessä teho alkaa laskea.
Käytännässä MT:n lento-ominaisuudet 5000 m:ssä ovat hieman erillaiset kuin matalalennolla lennettäessä. Kone on herkempi, taipuisampi ja helpompi ohjata kaarroissa.

"The maximum power gives out around 1355 HP, the max. continuous power is 1080 HP. From the figures one can figure out that MT has the best flying characteristics from 5000 to 5700 meters. Only higher than that the engine startes loosing power.
In practice the flying characteristics of MT are different in 5000 meters than in surface. The plane is more sensitive, flexible and easier to control in turns."

Nousua jyrkässä kaarrossa on syytä varoa, ettei koneen nopeus pääse liian pieneksi, sillä MT:kin voi joutua syöksykierteeseen nopeuden pienentyessä alle 250 km/t ja jos silloin ohjataan virheellisesti. Syöksykierteessä on huomioitava, että kone putoaa n. 1 km yhden kierteen aikana.

"Climbing in steep turns is to be avoided since if the speed is decreased below 250 km/h and if the aeroplane is not flown correctly the plane could enter in spin. The plane lose altitude around a kilometer per spin."

 

[HoHun]

Hi Mangrove,

Interesting comments, thanks a lot!

>Finns didn't use their "Mersus" at full power so the HP readings aren't the same as the German.

I believe they limited themselves to the German "Climb and Combat" power setting, avoiding the German "Take-off/Emergency" setting. I'm not sure if they used the take-off/emergency rpm at altitudes where the boost had fallen to the climb and combat figures, but as the idea was to preserve engine life, probably not.

(The latter mode of operation was used not only for some Daimler-Benz engines, but shows up in some British Spitfire tests as well, so the Finnish might have considered its use, too.)

Regards,

Henning (HoHun)

 

[Mangrove]

I believe they limited themselves to the German "Climb and Combat" power setting, avoiding the German "Take-off/Emergency" setting. I'm not sure if they used the take-off/emergency rpm at altitudes where the boost had fallen to the climb and combat figures, but as the idea was to preserve engine life, probably not.

Hello!

If my memory servers me corretly they removed the MW50 from the Gustavs and GM-1 from their few G-6/AS'. Indeed, the power setting was "fixed" too. The engine life was doubled or so, but the only thing made the Finns possible to use their Mersus until 1954 was the fact their managed to stole some engines from the Germans in 1944 and didn't hand them over to the Soviets.

 

[HoHun]

Hi Mangrove,

>The engine life was doubled or so, but the only thing made the Finns possible to use their Mersus until 1954 was the fact their managed to stole some engines from the Germans in 1944 and didn't hand them over to the Soviets.

LOL! First time I hear that - smart move!

I think most surviving Finnish Messerschmitts were retired after 200 to 400 flight hours - quite an accomplishment when the original manufacturer has ceased to exist!

Regards,

Henning (HoHun)

 

[Crumpp]

If my memory servers me corretly they removed the MW50 from the Gustavs and GM-1 from their few G-6/AS'. Indeed, the power setting was "fixed" too. The engine life was doubled or so, but the only thing made the Finns possible to use their Mersus until 1954 was the fact their managed to stole some engines from the Germans in 1944 and didn't hand them over to the Soviets.

Any A&P will tell you, if you want to save your engine, pull the throttle back.

 

[Mangrove]

Tulkoon tässä yhteydessä myös mainittua, että MT-koneella on mittarilentotehtävien yhteydessä edullista käyttää nousussa nopeutta 270 km/t., jolloin variometri osoittaa tavallisesti n. 10 m/sek. nousua. Liu'ssa teline sisällä nopeus 270 km/t. ja variometri 8 m/sek. Liuku telineet ulkona ja laskusiivekkeet auki 200 - 210 km/t., ja variometri osoitus 3-4 m/sek.

"It's best to use the speed of 270 km/h in climb when flying IFR. The variometer should show around 10 m/s. Diving with gears in, 270 km/t and 8 m/s. Diving with gears and flaps out, 200 - 210 km/h and 3-4 m/s."

 

[Mangrove]

Quite interesting... found some calculations about how long it takes to a squadron of Messerschmitts to take-off and land. For instance it takes 30-40 seconds to start the Bf-109 with two men, 30-38 seconds to taxi 300-500 meters and so on.