REFLECTOR: Interesting Angles -- Fuel Venting & Prop Strike

[Andrew Judge]

It's pretty tough to smell gas behind there. I had over 2 gallons leak out into the well under the sump and over the fuel pump once at the factory. None of us could smell it - and I aborted takeoff and came back. Then I flew to fort pierce. Only way I found out was to take off my cover at fort pierce.

That'd be one of my 9 lives...

Andy

________________________________
From: reflector-bounces at tvbf.org <reflector-bounces at tvbf.org>
To: 'Velocity Aircraft Owners and Builders list' <reflector at tvbf.org>
Cc: bobj at jaxtechllc.com <bobj at jaxtechllc.com>; Ron Marini (L3 Comm) <Ron.Marini at L-3com.com>
Sent: Sun Nov 27 21:18:40 2011
Subject: REFLECTOR: Interesting Angles -- Fuel Venting & Prop Strike

A little while back we were talking about how fuel is vented from the Velocity in steep climb angles when the fuel in the front part of the strake tank is higher than the vent loop normally routed to the top of the inside of the engine bulkhead  I'm interested in this because we periodically do smell a little fuel in the cockpit, and I think we are smelling wisps of the vented fuel, coming back in the main gear leg holes.

So I made some measurements and computed a few angles (Velocity XL RG with 93 gal strake tanks and vent loop as high to the ceiling as possible, but not routed forward -- which will allow steeper climb angle) that I thought people might be interested in the summary:

            Fuel                  Max Angle of Climb (without venting)
       ------------------    --------------------------------------------------------------------

            FULL                            12 deg
             3/4                               18 deg
             1/2                               36 deg

and if you were to extend the vent loop forward about 12" along the inside top of the fuselage:

            Fuel                  Max Angle of Climb (without venting, extended loop)
       ------------------    ------------------------------------------------------------------------------------------

            FULL                            14 deg
             3/4                               25 deg
             1/2                               63 deg

One other climb and rotation angle of interest is the maximum before your prop strikes the ground -- which could conceivably occur on take-offs, but more likely on a very slow, hard landing involving an over-rotated flare.  The GRT EFIS data from our flights indicates that our normal touchdown fuselage angle is 9 to 10 degrees -- plenty of margin!!

            Prop Strike       =          > 11 degrees pitch attitude

Bob Jackson
N2XF

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