Twin Engine Corvair powered JAG-2

Discussion in 'Corvair' started by Daleandee, Sep 1, 2018.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Sep 5, 2019 #41

    blane.c

    blane.c

    blane.c

    Well-Known Member HBA Supporter

    Joined:
    Jun 27, 2015
    Messages:
    3,270
    Likes Received:
    560
    Location:
    capital district NY
    Some would get flight plans in the C-130 from Anchorage through Canada and USA across the Atlantic to London. Some would take-off head directly over the north pole shut down 2 engines to save gas and use the time saved to stop off at Nuremburg to play with motorcycles at "the track" and arrive in London on schedule.
     
  2. Sep 5, 2019 #42

    FritzW

    FritzW

    FritzW

    Well-Known Member

    Joined:
    Jan 31, 2011
    Messages:
    3,672
    Likes Received:
    3,292
    Location:
    Las Cruces, NM
    ...errrrr, you might want to check the range charts before you try that.

    Shutting down an engine or two might gain you some low altitude, low speed loiter time but your range would be greatly reduced.
     
    BoKu likes this.
  3. Sep 5, 2019 #43

    blane.c

    blane.c

    blane.c

    Well-Known Member HBA Supporter

    Joined:
    Jun 27, 2015
    Messages:
    3,270
    Likes Received:
    560
    Location:
    capital district NY
    Go to thirty thousand feet. Drag is less of a penalty. Speed is reduced but so is distance over the pole and no additional fuel stop.
     
  4. Sep 5, 2019 #44

    FritzW

    FritzW

    FritzW

    Well-Known Member

    Joined:
    Jan 31, 2011
    Messages:
    3,672
    Likes Received:
    3,292
    Location:
    Las Cruces, NM
    With 4 good engines, no cago and low on gas you might get to 30,000'.

    On 2 engines you'd be scooching in the seat to get over a three wire fence. Especially on the beloved old 'E' model.

    Edit: and shutting down two engines would be a real systems challenge. ...you'd loose generators, 1/2 your bleed air, possibly the synchrophaser, etc...
     
    Last edited: Sep 5, 2019
  5. Sep 6, 2019 #45

    AdrianS

    AdrianS

    AdrianS

    Well-Known Member

    Joined:
    Jul 5, 2014
    Messages:
    384
    Likes Received:
    234
    Location:
    Australia
    Synchrophaser.

    What a lovely word. Nearly as good as turbo-encabulator (which is really 2 words anyway), although nothing beats "hypersonic retropropulsion".
     
  6. Sep 6, 2019 #46

    Turd Ferguson

    Turd Ferguson

    Turd Ferguson

    Well-Known Member

    Joined:
    Mar 14, 2008
    Messages:
    4,803
    Likes Received:
    1,727
    Location:
    Upper midwest in a house
    Obviously he has never flown a Champion Lancer.
     
    FritzW and BJC like this.
  7. Sep 6, 2019 #47

    Mike Stewart

    Mike Stewart

    Mike Stewart

    Member

    Joined:
    Oct 11, 2010
    Messages:
    19
    Likes Received:
    6
    Location:
    San Diego, CA
    In the twins that I'm familiar with, shutting down one and feathering the prop will gain range. I've no idea re three or four-engined aircraft although the same principle would apply I think, presuming the three or four-engined aircraft could maintain their altitude.
     
  8. Sep 6, 2019 #48

    FritzW

    FritzW

    FritzW

    Well-Known Member

    Joined:
    Jan 31, 2011
    Messages:
    3,672
    Likes Received:
    3,292
    Location:
    Las Cruces, NM
    On the multi's I'm familiar with, shutting down an engine might increase loiter time but it decreases range.

    When you loose 25% of your power the other three engines have to make up the difference. Add to that the increased drag from the lower altitude, the drag of the dead engine and prop and increased trim drag and the three remaining engines have to make up more than just one engines power and that takes more than just one engines fuel. And if you throttle back to match your 4 engine fuel flow you're going much slower for the same gas and that reduces range.

    If your light and your just circling the airport at low altitude waiting to land (loitering) ...maybe. But if you're heavy and/or your trying to get somewhere, you've already passed the point of diminishing returns.

    ...if shutting down an engine(s) in flight made the airplane more efficient then it would be a published procedure.
     
  9. Sep 6, 2019 #49

    proppastie

    proppastie

    proppastie

    Well-Known Member

    Joined:
    Feb 19, 2012
    Messages:
    3,811
    Likes Received:
    1,105
    Location:
    NJ
    seems to me in my Mooney if I pull the lever back I go slower, burn less fuel but have longer range....I am not sure where the best range is, but I think it is at best glide speed which is really slow, and really low fuel burn. Maybe that is what blane is thinking about. But I am not at turbine altitudes....
     
  10. Sep 6, 2019 #50

    FritzW

    FritzW

    FritzW

    Well-Known Member

    Joined:
    Jan 31, 2011
    Messages:
    3,672
    Likes Received:
    3,292
    Location:
    Las Cruces, NM
    Same thing in a C-130. you have a max range configuration. But working against a dead engine is a whole different can of Pringles.
     
    proppastie likes this.
  11. Sep 7, 2019 #51

    Vigilant1

    Vigilant1

    Vigilant1

    Well-Known Member Lifetime Supporter

    Joined:
    Jan 24, 2011
    Messages:
    4,071
    Likes Received:
    1,813
    Location:
    US
    I have heard that it is/was SOP for USCG C-130s to shut down the outboard engines when on patrol. I don't know if it was to lengthen time on station or to get more flight hours between engine overhauls. Note specifics:. An airplane with lots of power, thrust was symmetric, etc.
     
  12. Sep 7, 2019 #52

    Turd Ferguson

    Turd Ferguson

    Turd Ferguson

    Well-Known Member

    Joined:
    Mar 14, 2008
    Messages:
    4,803
    Likes Received:
    1,727
    Location:
    Upper midwest in a house
    On light twins feathering the prop is the only way to keep it airborne.
     
  13. Sep 7, 2019 #53

    FritzW

    FritzW

    FritzW

    Well-Known Member

    Joined:
    Jan 31, 2011
    Messages:
    3,672
    Likes Received:
    3,292
    Location:
    Las Cruces, NM
    It's to increase loiter time, P3's do it also. They're very light (lot's of gas but no cargo) and they just have to drone around in a patrol area, they don't have to get anywhere. They're hours per gallon might go up but they're miles per gallon goes way down.

    Just to be clear, I have absolutely no doubt blane.c has heard stories about C-130's shutting down engines and flying over the North pole. I'm just saying those stories might have been embellished a little. ...which is sad because it'd be the first time in history that an aircrew ever embellished a story <roll eyes>
     
  14. Sep 7, 2019 #54

    Heliano

    Heliano

    Heliano

    Well-Known Member

    Joined:
    Dec 24, 2015
    Messages:
    57
    Likes Received:
    30
    Location:
    Campinas, SP, Brazil
    I am a newcomer here, I just want to make a quick remark: There is a logic in shutting down one (or more) engine to increase range: engines tend to have a better SFC (specific fuel consumption) at higher power settings. And this better SFC can in fact compensate for asymmetric thrust, lower altitude, etc.
     
  15. Sep 7, 2019 #55

    TFF

    TFF

    TFF

    Well-Known Member

    Joined:
    Apr 28, 2010
    Messages:
    11,649
    Likes Received:
    3,281
    Location:
    Memphis, TN
    Gaining range is subject to a couple of things. One, being able to use the fuel in the dead engine tank. Certified planes have cross feeds, the Aircam I have access to does not. There are probably a few others out there for some reason that don’t. Another would be trim drag. The Voyager was supposed to shut down the front engine once at altitude. With the ripped up wing tips, the math decided they needed the thrust more than the extra fuel savings. Go fly an Apache on one engine, your not worried about range.

    The difference in full power speed and 80% power is usually not very much. Maybe 10 mph on a Mooney. Fuel burn is about 5 gal an hour difference. Probably 15 gal at full and 10 at cruise if I remember. Every hour you save 5 gal you get to go about 75 miles further for the 10 mph speed penalty. So going somewhere at 150 instead of 160 gains a lot of range. Less waisted time at fuel stops and less waisted money. Different if you race at Reno. If you can’t cross flow the fuel for some reason you are not going very far in a twin because it’s going to be at full power just to stay in the air on the one.
     
  16. Sep 7, 2019 #56

    blane.c

    blane.c

    blane.c

    Well-Known Member HBA Supporter

    Joined:
    Jun 27, 2015
    Messages:
    3,270
    Likes Received:
    560
    Location:
    capital district NY
    I don't know all the science, I do know people who used to do it. They were more concerned with playing with motorcycles for a day than worrying about minutia, like flying over the pole on two engines.

    There boss loaded a jeep onto the plane one time and they were routed over the pacific and several stops in Asia and a couple in Africa before ending up in Libya. That's when they found out that the plane had been sold to Gaddafi. Then they found out at the point of machine guns that the Libyan's were pissed because the good engines had been removed from the plane and run out engines had been replaced. Nice guy to work for that one.
     
  17. Sep 7, 2019 #57

    blane.c

    blane.c

    blane.c

    Well-Known Member HBA Supporter

    Joined:
    Jun 27, 2015
    Messages:
    3,270
    Likes Received:
    560
    Location:
    capital district NY
    Civilian model What was it … I think like a L-382? Quite a bit stretched over the standard military version, I think the engines were different too.
     
  18. Sep 7, 2019 #58

    blane.c

    blane.c

    blane.c

    Well-Known Member HBA Supporter

    Joined:
    Jun 27, 2015
    Messages:
    3,270
    Likes Received:
    560
    Location:
    capital district NY
    I would like to see you tell David and Jerry they couldn't fly over the pole on two, they would laugh so hard. After they were successful once they did it so many other times, it was the fun at the track in Nuremburg, that was a lure they couldn't resist. It was a different era late 70's early 80's and you could get away with it.
     
  19. Sep 7, 2019 #59

    blane.c

    blane.c

    blane.c

    Well-Known Member HBA Supporter

    Joined:
    Jun 27, 2015
    Messages:
    3,270
    Likes Received:
    560
    Location:
    capital district NY

Share This Page



arrow_white