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Hot!b17 fuel and speed questions

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Rockers79
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2009/01/22 10:23:33 (permalink)
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b17 fuel and speed questions

Hello some question about B17 G
1 How much fuel does the engines consume per hour at cruising speed.
2 And if you have lost one engine. what is the speed the aircraft has with 3 engines?
 
Best regards Mattias Eneqvist Sweden

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    jpeters140
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    Re:b17 fuel and speed questions 2009/01/22 10:46:16 (permalink)
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    Mattias....Each engine consumed approximately 50 gallons per hour. Om missions, it was 100 gals per hour....we used 3/4 of our gas to the target and 1/4 returning to base, as it was all downhill and the bomb load was gone.

    As to your second question, there are too many variables for a fast answer.

    Are you asking about a return from a mission ? 
    Are you asking about a ferry flight...transporting the aircraft to a new location ?

     I think an aircraft with one engine out, could keep up with the formation...I watched  two B-17Gs land with two engines out on one side, and they returned with the formation.

    I don't know the airspeed required to keep up with the formation, and my book, (Pilots Handbook) does not have a chart that shows such an event.

    Jim :-)


    James S. Peters Sr. T/Sgt B-17 Flt Engr, 27 missions 99 BG, 348BS, 5th Wing, 15th AAF Tortorella, (Foggia#2), Italy My Tour was from 12/03/44-06/19/45 M/Sgt USAF (Retired)
    billrunnels
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    Re:b17 fuel and speed questions 2009/01/22 13:30:09 (permalink)
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    jpeters140

    Mattias....Each engine consumed approximately 50 gallons per hour. Om missions, it was 100 gals per hour....we used 3/4 of our gas to the target and 1/4 returning to base, as it was all downhill and the bomb load was gone.

    As to your second question, there are too many variables for a fast answer.

    Are you asking about a return from a mission ? 
    Are you asking about a ferry flight...transporting the aircraft to a new location ?

     I think an aircraft with one engine out, could keep up with the formation...I watched  two B-17Gs land with two engines out on one side, and they returned with the formation.

    I don't know the airspeed required to keep up with the formation, and my book, (Pilots Handbook) does not have a chart that shows such an event.

    Jim :-)


    Hi Jim,
     
    I think you are a little heavy on quoted fuel per engine use (100 gal.) on missions. That would be 400 gal. per hour for the aircraft. Based on 2780 gal. total fuel capacity, you would have less that 7 hours of flight time.  My longest mission was 11 hrs 30 mins.  The quoted 50 gal. per engine per hour is far more accurate even on missions.

    Bill Runnels
    Bombardier(B-17)
    8TH Air Force
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    billrunnels
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    Re:b17 fuel and speed questions 2009/01/22 13:57:04 (permalink)
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    Rockers79

    Hello some question about B17 G
    1 How much fuel does the engines consume per hour at cruising speed.
    2 And if you have lost one engine. what is the speed the aircraft has with 3 engines?
     
    Best regards Mattias Eneqvist Sweden


    As Jim has stated, there are to many variables to figure the speed on three engines. However, if climbing in formation with a full bomb load, You could not keep up with the formation.  We tried on one mission, had to abort and return to base on three engines.

    Bill Runnels
    Bombardier(B-17)
    8TH Air Force
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    jpeters140
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    Re:b17 fuel and speed questions 2009/01/22 14:35:27 (permalink)
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    Bill....Most of my missions were around   6 to 7 hours ...my longest mission was 7 hrs and 50 minutes. ....and I have to note that we had to clear the Alps to and from our targets, in the 15th AAF. In my opinion, there was not the requirement for the 8th AAF  to climb as  rapidly, as your flights were over mostly flat land.  Please correct me,if I am incorrect.
     
    On th elongest mission to Berlin of the 15th AAF to the Daimer Benz tank factory, the B-17s were dropping into fighter fields from Rome southward, although I did hear of one B-17 that returned with 600 gals in it's fuel tanks.

    There are many wrecks on the glaciers in the Alps, of aircraft with problems, that could not climb high enough to make it over the mountains. This was for both  the 12th and 15th AAFs and the 205 RAF aircraft, in the Mediterranean.

    Jim :-)




    James S. Peters Sr. T/Sgt B-17 Flt Engr, 27 missions 99 BG, 348BS, 5th Wing, 15th AAF Tortorella, (Foggia#2), Italy My Tour was from 12/03/44-06/19/45 M/Sgt USAF (Retired)
    billrunnels
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    Re:b17 fuel and speed questions 2009/01/22 16:49:29 (permalink)
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    Jim, you are correct. We did not have mountains to clear etc.  Our rate of climb was calculated to give us 20,000 ft. when crossing the enemy line.  We continued the same rate until reaching bombing altitude.

    Bill Runnels
    Bombardier(B-17)
    8TH Air Force
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    jpeters140
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    Re:b17 fuel and speed questions 2009/01/22 18:43:28 (permalink)
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    Bill...As the flight engineer, one of my duties was to monitor the engine instruments.....our cyl head temps were on the red line (max allowable) constantly during our climb.

    Jim :-)

    James S. Peters Sr. T/Sgt B-17 Flt Engr, 27 missions 99 BG, 348BS, 5th Wing, 15th AAF Tortorella, (Foggia#2), Italy My Tour was from 12/03/44-06/19/45 M/Sgt USAF (Retired)
    Rockers79
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    Re:b17 fuel and speed questions 2009/01/23 03:03:29 (permalink)
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    Thank you.
    At my second question, was if a engine was knockt out by flack,
    did the aircraft lost lot of speed, how much.
    mybe depends on the damages.

    Best regards Mattias Eneqvist
    Nextgen
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    Re:b17 fuel and speed questions 2009/01/23 21:55:37 (permalink)
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    I have a friend whose plane lost two engines (same side) near Berlin and just barely made it to Sweden. They threw out everything they could, including the ball turret. A few of the variables on the range might be whether the dead engines were feathered or windmilling, loss of fuel, aerodynamic damage (extra drag) and the condition of the remaining engines.
    Incidentally my friend took lot of pics while interned at Loka Brune.
    bernies
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    Re:b17 fuel and speed questions 2009/01/24 16:12:21 (permalink)
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    When flying in tight formation at altitude, how did you typically handle the mixture controls?  It would seem to me that with a comparatively high degree of throttle movement to stay in position it would not be possible to do a lot of leaning out of the mixture.   

    Bernie Shearon
    Push the stick forward, the houses get bigger. Pull the stick back, the houses get smaller (unless you keep pulling -- then they get bigger again)
    jpeters140
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    Re:b17 fuel and speed questions 2009/03/01 02:27:31 (permalink)
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    Bill... to answer your reply about fuel consumption...we used 3/4 of our fuel outbound to the target and 1/4 returning...it was all downhill on the return.
    And yes the fuel consumption was 400 gals/hour in climb, with the Cylinder Head Temps red lined.
     
    as previously stated, we had to climb to clear the Alps, which I assume meant that our climb rate was more severe than the 8th AAF, thus the fuel consmption rate was greater,in the15th AAF.
     
    Jim :-)

    James S. Peters Sr. T/Sgt B-17 Flt Engr, 27 missions 99 BG, 348BS, 5th Wing, 15th AAF Tortorella, (Foggia#2), Italy My Tour was from 12/03/44-06/19/45 M/Sgt USAF (Retired)
    Rockers79
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    Re:b17 fuel and speed questions 2014/02/19 02:31:04 (permalink)
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    Thank you all for the answere
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