Do Not Exceed speed later Bf109s

Discussion in 'Aviation' started by kettbo, Mar 21, 2015.

  1. kettbo

    kettbo Member

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    Someone posted on an internet site the Do Not Exceed speed of the Bf109 was almost always 750km/hr /466mph
    He also wrote the Bf109 was one of the slower-diving planes of WW2

    With Bf109G-10 speed of 428mph or there about Bf109K-4 a tad faster, then some crazy stuff in anti-Mosquito units you're knocking on the door of this 750km/hr supposed limit.

    I have a book, test diving Bf109 is covered...not able to remember which book it is in.

    750 km/hr limit, Fact or Fiction?
     
  2. Koopernic

    Koopernic Active Member

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    #2 Koopernic, Mar 22, 2015
    Last edited: Mar 22, 2015
    I think there are two aspects to 'slow diving'
    1 Acceleration into the Dive
    2 Peak Speeds from which the aircraft can recover.

    The Me 109 was generally one of the faster diving aircraft of WW2, faster than say the P-38 and P-47 until those aircraft received dive recovery flaps to slow the aircraft down and pitch up the nose to overcome Mach Tuck. The Me 109 out accelerated the Spitfire in a dive though in terms of maximum speed the Spitfire eventually caught up. I think the achievements of modified post war photo reconnaissance spitfires can be ignored as far as combat evaluation in WW2 goes.

    The USAAF pilots even reported Me 109G out diving P-51D (bubble top) Mustangs.

    Late Me 109G6, G14 and as standard G10 and K4 received a new taller vertical tail. Instead of a rudder having a 'horn balance' it had 'balance tabs' and this raised the Mach limit from about 0.75 to 0.8+.

    Note old style tail, rudder and horn balance on this G6
    Bf109G_6.jpg
    Note new style tall tail, rudder and rudder balance tabs replacing the horn balance on this G10. Also note the absence of the gun blisters. A K4 would have had a retractable tail. The extended tail yoke also eliminated much of the Me 109's reputed ground looping problem. You can also not the clear view ERLA hood that improved vision and the bullet proof glass headrest that replaced steal armour also improving rear view.
    Bf109G_10.jpg
     
  3. Jaivan

    Jaivan New Member

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    Actually, the limits were increased. The requisites (laid off in TAGGT 151/152) were:
    - tall tail
    - limited horizontal stabilizer upwards movement to +1º10'
    - enlarged elevator fixed tab (350 mm)
    - reinforced ailerons (8 mm Ø bolts)

    The dive limits were (new/old):
    · For standard airspeed indicator (Fl. 22234):
    11 km 400/400 km/h
    9 km 500/500 km/h
    7 km 600/600 km/h
    5 km 700/700 km/h
    3 km 800/750 km/h
    1 km 850/750 km/h

    · with altitude-corrected indicator (Fl. 22245):
    11 km 800/800 km/h
    9 km 800/800 km/h
    7 km 800/800 km/h
    5 km 850/800 km/h
    3 km 850/800 km/h
    1 km 850/800 km/h

    The proof-test flights were carried out by Mtt AG in June-July 44 (results given in VB 109 06 E 44 850 km/h - Nachweisflüge mit Me 109 G v. 8.7.44 and VB 109 10 E 44 850 km/h - Nachweisflüge mit erleichtertem Holzleitwerk BBBC v. 17.7.44).

    HTH
     
  4. kettbo

    kettbo Member

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    Nice info! Welcome to the site Jaivan!
     
  5. GregP

    GregP Well-Known Member

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    Won't be pulling out very hard at an elevator movement of 1° 10'!

    Better avoid the crap out of that unless you start the pullout at 15,000 feet!

    Let's recall how many Bf 109s went in from a steep dive and take this with a large grain of salt, not from what was stated (I believe it), but from a combat standpoint. Best not start pullout from 2,500 feet!
     
  6. Juha

    Juha Well-Known Member

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    #6 Juha, Mar 24, 2015
    Last edited: Mar 24, 2015
    Hello Greg
    it wasn't elevator movement but horizontal stabilizer upwards movement
    Hello Koopernic
    Spit PR XI wasn't a post war photo reconnaissance spitfires, it wasn't even the last war-time PR Spit version in WW2, simply the last Merlin Spit PR version. But it wasn't totally comparable with fighter versions lacking the gun barrels and rear-view mirror. In combat trim Spit IX's max would probably be more like 0.83-0.85, more or less same than that of P-51B. And max allowed speed of Spit IX was lower than that of 109G.

    On 109, from my old answer
    the highest Mach number achieved in tests flights by 109 I'm aware was Mach 0.805.

    It was achieved when in order to find the explanation of accidents in the front-line units the flight test unit of Messerschmitt made series of dive tests during spring 1943. The plane used was Bf109 F W.Nr. 9228. To reduce the risk of pilot over-compensation, the control movement was limited to 50% of the reference movement of the ailerons. For the first test flights the plane was in the standard condition of a 109F with G-wings, except for the movement limitation of the ailerons and the ejection seat. At this form the plane lost stability (at median centre of gravity) at speeds over Va=650 km/h ie IAS. Movements, starting at the vertical stabilizer;appeared around the yaw and longitudinal axes.
    After this the stabilizer was changed to a larger one. Meaning the late production higher one. The elevator trim tab is enlarged in surface area by 100% compared to the original lower version. The horizontal stabilizer trim is limited in its upwards range of motion to +1°15 by a stop unit. With this new tail following speeds were achieved.
    Maximum IAS Vamax = 737 km/h at 4.5 km, Maximum TAS Vwmax = 906 km/h at 5.8 km Maximum mach number = 0,805 at 7.0 km. This is the highest Mach number flown by 109 I’m aware. Bf 109K might well be capable to a bit higher max Mach number but was it ever tested flown in order to achieve that, I don’t know.

    and extra info given by Ratsel in that ld thread http://www.ww2aircraft.net/forum/aviation/eric-browns-duels-sky-30566-3-print.html

    Hello Juha, Thanks for this information. Very informative. The fastest speed I found was with Bf 109G-10 US serial number "T-2-122" [ex FE-122]which achieved transsonic speed of Mach .82 or about 966kph.
     
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