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Fuel Flow Test question...what pitch settings?

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  • Fuel Flow Test question...what pitch settings?

    There is a good discussion going on in another area of the forum on fuel system design that referenced this service bulletin from Glastar. gssb43revb.pdf The service bulletin talks the fuel quantity test and about the degrees of pitch that their aircraft achieves in various realms of flight in order to perform a fuel flow test.

    When the fuel flow test is performed, the pitch attitude of the fuselage must set at the most extreme setting that will be achieved in normal flight to ensure that sufficient fuel flow is available in that configuration and to define amount of unusable fuel that exists in each tank.

    I do not know nor have I ever seen published what pitch setting that is. What is acceptable for us? What pitch setting results in attaining Vx at 100% power while weighing 1400 pounds? In the descent, what pitch setting would result in a power off glide at Vfe with full flaps?
    Brooks Cone
    Southeast Michigan
    Patrol #303, Kit build

  • #2
    Warning, anecdote: I can say that climbing out of Stehekin in Mike Creek's 250hp 4-place with 3 aboard at 65-70 mph was quite steep.

    It seems like in those steeper pitch attitudes, the head pressure would increase as the column of fuel vertically would actually increase in height (at least for the outlet that counts.)
    Last edited by Zzz; 05-08-2018, 03:15 PM.

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    • #3
      Hey I plan to go into Stehekin here for the first time when they open it up!

      But wouldn't the max head pressure, at the fuel valve in this case, be in level flight? Thinking when you pitch up you're rotating the fuel valve about the wings and moving it up in relation to the (rear) tank pickups? If we're talking minimum fuel, which I believe is the scenario to be tested for flow rates.
      Dave B.
      Edmonds, WA
      4 Place Quick Build

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