wallboy Posted February 3, 2014 Share Posted February 3, 2014 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 Quote Link to comment Share on other sites More sharing options...
Guest Posted February 4, 2014 Share Posted February 4, 2014 Yes SW Quote Link to comment Share on other sites More sharing options...
Christoffel Posted February 5, 2014 Share Posted February 5, 2014 is "more fuel" means per hour or per km? if per hour than after convert to per km will be about the same because it has more speed ... Quote Link to comment Share on other sites More sharing options...
morgy Posted February 5, 2014 Share Posted February 5, 2014 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 Hope that makes sense. Quote Link to comment Share on other sites More sharing options...
Christoffel Posted February 6, 2014 Share Posted February 6, 2014 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 ... Quote Link to comment Share on other sites More sharing options...
nigel_d. Posted February 6, 2014 Share Posted February 6, 2014 I wonder what you are getting currently. with me being 85 kg (wet) under my 29 nuke and V5 I have a range of about 165 miles. Nige Quote Link to comment Share on other sites More sharing options...
morgy Posted February 10, 2014 Share Posted February 10, 2014 165km's ??? is that a rough est with no wind 165m or 265km is a huge range Nigel... do you have the 15 ltr tank fitted?? I currently run 3.1LPH on full fast trim on my 24m speedster low 2's for slow trim... Quote Link to comment Share on other sites More sharing options...
nigel_d. Posted February 11, 2014 Share Posted February 11, 2014 Miles! (assuming nil wind but even more with a tail wind) I have a 15 litre tank and burn about 2.4 litres an hour when trimmed at about 26-27 mph. Nige Quote Link to comment Share on other sites More sharing options...
morgy Posted February 11, 2014 Share Posted February 11, 2014 Arrgg the 15ltr tank!!! Don't do mph when flying... I only refer to trims in/out or on bar to people 23mph means nothing depending on your wing and wing loading... Don't think i can fly that slow on my 16m Quote Link to comment Share on other sites More sharing options...
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