Which is the longest range GA aircraft?

[AN2 Driver]

I've seen some pretty interesting flights done with Twin Commanches with the standard tip tanks, I'd rate that one as a pretty LH aircraft.

Also the Robin HR100 Series has pretty long legs with up to 10 hrs endurance at 130-140 kts, that is 1300 NM.

Mooneys are of course very efficient but with additional tanks is where it gets interesting. My "C" will do about 650 NM with standard tanks, were I to add Monroy tanks (36 USG additional fuel) I'd think 1200 NM should be possible (including 45 mins reserve). However, this comes at a price. With full standard tanks (52 USG) I can still fit roughly 270 kgs, with the Monroys I'd be flying alone with 170 kgs maximum payload left. That is why I have so far not installed the Monroys.

The newer Mooneys can of course do a lot more, the Ovation as has been advertized with a 1800 NM regular and 2400 NM long range tank range. Guess that would make it top of the class. Rough calcs on payload however sais, this plane will lift around 150-180 kgs out at the full 128 USG long range tanks, with the standard 100 USG tanks it would be 220 kgs. So even with standard tanks, which give 1800 NM according to Mooney but probably rather something in the line of 1500 NM with reserves, you'll be at the limit with 2 grown ups and their bags.

I've been discussing these issues with some of the newer manufacturers on different airshows. Looking at some designs which are currently certified in the LSA class but which could do a lot more were it not for certification issues, might provide pretty interesting figures. Long haul travel in small planes are mostly done with one or two people on board plus baggage. Those engines use a lot less fuel then even an O360 let alone an O550. Quite a few of them have "artificial" MTOW's in order to put them in the LSA/VLA e.t.c. cathegory but could structurally or wifh modifications do a lot better. So I reckon, some pretty interesting designs might be possible if those planes were certified in the normal catheogry.

Say, a 2 seater which currently is certified to 600 kgs MTOW with a 75 hp Rotax and which has been "doctored" to not go over the 120 kts these planes can do. Fit a 125 or 140 hp engine in front, up the MTOW to 999 kgs and see what happens?

These things weigh about 300 kgs empty as LSA's, so allow 150 kgs on top for the larger engine and structural inprovement. 450 kgs empty. Add 2 "normal built" adults with 220 kgs and their bags with 60 kgs gives a ZFW of 730 kgs. With a projected MTOW of 999 kgs, that leaves space for 370 liters of fuel. Now, if we get even bolder and say we bolt a 150 hp O320 in front which will use around 30 liters per hour, that is 11 hours endurance plus reserve, @ speeds of maybe 140/150 kts? 1600 NM still air range with 330 liters of Mogas? Or, as some designers claim, their planes would do 180 kts with this kind of power and the same fuel flow? 2000 NM.

One test pilot of one of those designs told me they did try their prototype with a 125 HP engine out of a C152 and up to 750 kgs of weight for which the kit was originally designed. Sais, pity I can't show it to you,you'll want one. 130 kts @ 24 lph. Even with the standard tanks they use for the Rotax, that is a solid 4 hour endurance or 500 NM, but there is 150 kgs to spare which could translate into more fuel, without breaching any legal limits. Now get a more modern engine which may do the same for 20 lph?

Somehow I hope someone comes up with a design like that....

Best regards
AN2 driver