FreeflyerNZ Posted March 12, 2011 Share Posted March 12, 2011 After a bit of advice again please, I have been using about 5 ltrs per hour with my coastal flights where fuel consumption is not too much of a concern, a fair amount of assing about really, climbing, climbing hard, swooping, periods of low level flight and general smooth and level flight, but tomorrow we are doing a trip down the coast (70km each way) and return (conditions and body permitting). I have done a search that really didnt answer my question. We will be flying low level (under 200ft) for most of the 70km flight, and although we have a support team carrying extra fuel, ideally I would like to fly without needing to land for more fuel until we get to our turnpoint/destination. Forecast is for light seabreezes (3-6 knots) so if anything we will generally be flying with the breeze at our sides or slight head or tailwind. Obviously flying level and smooth is ideal, but I guess the question comes down to trim settings, provided we are making good speed I would prefer to fly with trimmers on, wing turns much better with less brake input for low level flight. Trimmers fully out, best speed but will need to compensate by using more power to maintain level flight and not as responsive/sporty. Any words of wisdom, compromise between the two or full relfex etc? Flying with Sky 100 with triple blade 122cm prop and medium Ozone Roadster Thanks Rob Quote Link to comment Share on other sites More sharing options...
gordon_dunn Posted March 12, 2011 Share Posted March 12, 2011 I guess the best ways to conserve fuel is to use it wisely. Take off on full power, but when climbing don't use full throttle as it is extremely inefficient on most 2 strokes - approx 20-25% of fuel passes out of the exhaust unburnt at full throttle. Keep climbs gentle as possible and fly at a constant altitude when ever possible on neutral trims. When possible, exploit natural lift, circling if necessary to gain as much height as possible- with engine on idle. After gaining altitude, put fast trims on and dash to the next waypoint. Once you've got to your cruising altitude again, put trims on neutral and go back to cruise engine speed. 5 litres per hour is quite heavy consumption.... my average is 3 GD Quote Link to comment Share on other sites More sharing options...
aquatix Posted March 12, 2011 Share Posted March 12, 2011 Any words of wisdom, compromise between the two or full relfex etc? Probably somewhere around neutral trim will be best in nill / side wind. With trimmers out (fast) you will arrive sooner but burn more fuel. Trimmers in (slow) is more efficient but slower, so you will still burn more fuel over the longer period. Think how 56mph for a motor car is more efficient than 30 or 80 .... McCready curves (for best glide on an XC) suggest it is always best to speed up against a headwind and slow down with a tail wind. As Gordon says, 5l per hour sounds excessive. Its worth checking your carb is correctly tuned, and maybe the thrust angle of your prop ? How come you will be flying so low ? You may find more favourable wind higher up, plus you could fly hands off, and maybe feet forward on a stirrup to reduce drag and improve efficiency. Quote Link to comment Share on other sites More sharing options...
FreeflyerNZ Posted March 12, 2011 Author Share Posted March 12, 2011 Any words of wisdom, compromise between the two or full relfex etc? As Gordon says, 5l per hour sounds excessive. Its worth checking your carb is correctly tuned, and maybe the thrust angle of your prop ? How come you will be flying so low ? You may find more favourable wind higher up, plus you could fly hands off, and maybe feet forward on a stirrup to reduce drag and improve efficiency. 5l per hour, I'm hoping it's because I have been flying experimentally most of the time, getting to know how we fit together and how things work rather than pure sight seeing, experimenting with climb rates, flying the terrain as I would free flying when ridge soaring. But it definately could do with an expert to tune it and check the ratio's. I guess we fly so low right here because our local tower asks us too in the area we fly most often (our front doorstep as such), most of my freeflight experience was ridge soaring, so close terrain flying feels natural, more dynamic and definately hands on eyes open. Good for short bursts when the terrain permits. The seabreeze combined with the right height should help reduce sink rates on some of the larger cliff areas, one part gets up to about 500 feet so should be easily soarable, hadnt really considered that too much, thinking more about the destination instead of the journey. Thanks guys, some really helpful information there. Quote Link to comment Share on other sites More sharing options...
aquatix Posted March 12, 2011 Share Posted March 12, 2011 Your lucky to have such a friendly control tower. Its much more fun flying low with the terrain than just a long cruise A - B at 2000 feet. Look forward to some photo's / video. Quote Link to comment Share on other sites More sharing options...
tj Posted March 13, 2011 Share Posted March 13, 2011 How do you talk to your tower? Quick phone call first or by vhf? Tj. Quote Link to comment Share on other sites More sharing options...
FreeflyerNZ Posted March 13, 2011 Author Share Posted March 13, 2011 Your lucky to have such a friendly control tower. Its much more fun flying low with the terrain than just a long cruise A - B at 2000 feet.Look forward to some photo's / video. Yeah we are lucky, cruised up to 1500ft briefly to clear a peninsula on my way home yesterday, hell of a view. No photo's or video just yet though, concentrating on my flying for a few more hours before I take my DSLR up. How do you talk to your tower? Quick phone call first or by vhf?Tj. Tj, I just give the tower a quick ring beforehand, asking for permission to launch and general flight plan, altered if required. My first decent point to point didnt work out with the other pilot backing out at the last minute, so ended up driving down the coast with a couple of mates (support crew) and I flew a new coastal area that you really cant access when freeflying....freedom! Ended up flying home from there after a fuel top up, 45km as the crow flies into a slight headwind from the moderate seabreeze, awesome flight but used the entire tank (10l) on the almost 2 hour flight so will take into the local expert for an adjustment. With a support crew following I flew for speed rather than economy, trimmers fully off and hands off when high enough, and as the last 10km has excellent access and nice wide beaches to land on should I run out I wasnt worried about running dry, landed at my home LZ with about 10mm of fuel in the bottom of the tank. My new self retracting mirror proving invaluable. Quote Link to comment Share on other sites More sharing options...
bignos Posted March 16, 2011 Share Posted March 16, 2011 just a note, i use 7 litres / hour!!! Quote Link to comment Share on other sites More sharing options...
Guest Posted March 16, 2011 Share Posted March 16, 2011 just a note, i use 7 litres / hour!!! I guess your not the best person to ask about economy then SW Quote Link to comment Share on other sites More sharing options...
notch Posted March 16, 2011 Share Posted March 16, 2011 FreeflyerNZ, where abouts in NZ are you based? Nick Quote Link to comment Share on other sites More sharing options...
bignos Posted March 16, 2011 Share Posted March 16, 2011 just a note, i use 7 litres / hour!!! I guess your not the best person to ask about economy then SW lol, errr nope! Quote Link to comment Share on other sites More sharing options...
FreeflyerNZ Posted March 17, 2011 Author Share Posted March 17, 2011 just a note, i use 7 litres / hour!!! I guess your not the best person to ask about economy then SW lol, errr nope! 7lt per hour, Lexus V8? haha, speaking of poor fuel economy, my boat can use 60lt per hour!!! FreeflyerNZ, where abouts in NZ are you based?Nick Im in the Bay of Plenty area Nick. Quote Link to comment Share on other sites More sharing options...
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