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Cross Country Weight Range


wallboy
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I am looking to complete some cross country flights this summer and was wondering where I need to be in the weight range on a wing for completing long distance flights while using little fuel.

Am I correct in thinking:

  • *Being at the bottom end will use less fuel but fly slower
    *Being at the top end will use more fuel and but fly faster

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You have to do a few tests...

Slow trim fuel burn for as long as you can, The longer the better as it will get rid of the full throttle take off and climb out to say 1000ft...

Fast trim fuel burn same as first test for as long as poss. I normally just do an hour for each.

Then you have to test you ave speeds on the slow and fast trim. Then you can work out your KM/per/LTR this will give you your best flying speed verse fuel burn...

Now it can get complicated if your doing a closed circuit, depending on the wing and wind speed...

Best fuel burn is always @max glide.

If you want to do good long XC's there is only one motor to have :wink:

Hope that makes sense.

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Agree with Morgy ..

I thing the fuel consumption curve (vs trimmer position) would be an inverted parabolic, so you should do a few test with your own engine and canopy combination to get the best trimmer position ...

No need to fly hours, just set the desired trim position, adjust the throttle to make it at cruising speed (not climb or sink) and write down the speed vs RPM. repeat for few other trimmer position. Assuming the RPM is linier to fuel consumption (would be better if we already have data for RPM vs fuel burn rate), we can calculate and draw the fuel consumption curve and pick the best trimmer position to apply ...

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