GPH in 182 today - towing gliders

Discussion in 'Technical Corner' started by saddletramp, Oct 9, 2017.

  1. saddletramp

    saddletramp Line Up and Wait

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    I use my 182A steam gauge as a tow plane in our small glider operation. We just started our business in May. This weekend I had 9 visiting sailplanes from a distant soaring club.

    I towed for three hobbs hours today. That ended up being 12 tows.

    When I fueled up at the end of the day I pumped 23.8 gallons of 100LL into the tanks. I filled it yesterday so I know the tanks were filled consistently both times.

    That's around 8 GPH! I really thought towing gliders would burn much more fuel.

    No big issue here i just found it surprising.
     
  2. luvflyin

    luvflyin Final Approach

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    Hmm. Ain't no cruise. Yeah, your lugging a lot of weight up but then after that it's downhill all the way. And your sittin there at idle for a few minutes each cycle, so doing your 'gallons per Hobbs minute' I guess it passes the logic check
     
  3. bnt83

    bnt83 Final Approach

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    A 182 isn't all that thirsty if you don't want to run it that way, plus you still get to enjoy decent load hauling and better climbs to boot. It really is a nice marriage of power & utility.

    Also why I have a hard time buying an "in between model" like the 172XP/177B (amazing airplanes but on the pricy side). If I'm paying for a constant speed prop it might as well be attached to an engine over 200 horse that burns cheap 87 mogas.
     
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  4. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser!

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    Do you think 2 hours (12 tows x 10 mins) was under full power and 1.0 (12 tows x 5mins) was at or near idle?
    The 1 hour 'coast' part might affect the total average burn in this way.
     
  5. bijanmaleki

    bijanmaleki Pre-Flight

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    Sitting and idling waiting to launch helps those numbers a lot. I have seen the pawnee between 12-16gph depending on the type and frequency of tows we were doing.
     
  6. BillTIZ

    BillTIZ Final Approach

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    We run a Pawnee with an O-540 at 250HP. I plan about 12gph in full tow mode. Full power climbs and 2000 rpm slowing to 1500rpm on descent. Lean in the climb for best power.

    Depending on how high the tow we avg 4-5 tows per tach hour.
    We can climb a lot quicker than a C-182 so our tows go faster.
    I’m surprised at the low fuel burn you have.
     
  7. BigBadLou

    BigBadLou Final Approach

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    What was your tach hour difference?
     
  8. BillTIZ

    BillTIZ Final Approach

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    Saturday, 1.3 on the Tach, 5 pattern tows, one 3.7K Tow, 9.6 gallons.

    I always factor 1.3xtach for logbook. I have never really compared the Pawnee tach against a watch because of idle time and reduced power descents.
     
  9. GLMS_NC

    GLMS_NC Line Up and Wait

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    You didn't say what altitude you hit or the climb rate, unless I missed it. Both heavy contributors to fuel burn. But your number doesn't surprise me.
     
  10. saddletramp

    saddletramp Line Up and Wait

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    Most tows were 3000' AGL. Our airport elevation is 750 ft MSL so that means we're towing to 3,750 MSL. Average climb rate is about 400 ft/min depending on air stability & glider weight.
     
  11. BillTIZ

    BillTIZ Final Approach

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    For the Pawnee, climb rate between 500-800fpm, did see 1000fpm for part of it going through a shear line.
    Pattern tows are 1k AGL, had one Tow to 3.7k AGL. Our airport is at 2833MSL.
     
  12. ljsuter

    ljsuter Filing Flight Plan

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    12 tows to 3000' is 36,000'. At 400fpm, that's 90 minutes at full power. Guessing 0.45#fuel/hp-hr, 230hp, that's 155# or about 25 gal. So your fuel consumption would seem to be in the right ballpark.

    Larry