17.5

Only one engine sucking fuel. You can fly a SETP like you fly any piston plane if you want to avoid winter winds. 85gph is a lot more doable at 290kt, than a KA350 sucking down 170gph at this altitude. In case of the TBM, the range is cut by 25%, in case of the KA350, the range goes down 40%, in case of a jet, well, I have no idea.

Only one engine sucking fuel. You can fly a SETP like you fly any piston plane if you want to avoid winter winds. 85gph is a lot more doable at 290kt, than a KA350 sucking down 170gph at this altitude. In case of the TBM, the range is cut by 25%, in case of the KA350, the range goes down 40%, in case of a jet, well, I have no idea.

Only one engine sucking fuel. You can fly a SETP like you fly any piston plane if you want to avoid winter winds. 85gph is a lot more doable at 290kt, than a KA350 sucking down 170gph at this altitude. In case of the TBM, the range is cut by 25%, in case of the KA350, the range goes down 40%, in case of a jet, well, I have no idea.

The only time I would burn 85 gph in the TBM is at 500 ft, 17.5 is in the 60-65 gph.
I rarely fly there unless on a short flight and locally when I know the airspace, im too lazy to fly vfr. Im IFR all the time at FL270/280.
I take the headwinds like a man, very rarely does it help staying low.







Only one engine sucking fuel. You can fly a SETP like you fly any piston plane if you want to avoid winter winds. 85gph is a lot more doable at 290kt, than a KA350 sucking down 170gph at this altitude. In case of the TBM, the range is cut by 25%, in case of the KA350, the range goes down 40%, in case of a jet, well, I have no idea.

You do know that the SAME basic engine is on the TBM and KA350? PT6A-6x series.

I wonder how the engine knows to burn more fuel if it is mounted on a King Air? Pratt really has some interesting technology, some sort of "twin induced fuel consumption" sensor that burns more fuel if mounted on a twin.

In other words, your statement is bogus. Flying lower will have essentially the same effect on fuel flow and speeds for both aircraft, thus affecting range about the same.

Mike C.

You do know that the SAME basic engine is on the TBM and KA350? PT6A-6x series.

I wonder how the engine knows to burn more fuel if it is mounted on a King Air? Pratt really has some interesting technology, some sort of "twin induced fuel consumption" sensor that burns more fuel if mounted on a twin.

In other words, your statement is bogus. Flying lower will have essentially the same effect on fuel flow and speeds for both aircraft, thus affecting range about the same.

Mike C.

You don't buy a jet, even a $2.5M toy one, to be "stuck low".

One can already tell from the specific range chart that the jet will slow down a lot in thicker air. The speed of maximum range, 210 KTAS at FL280, is only 135 knots indicated, an awfully low airspeed for best range.

Mike C.

Actually, incorrect assumption and I actually gave you wrong numbers. Just pulled up a TBM 850 POH. 5000 feet, max cruise, 80, gph, 252TAS. What's the 421 doing there? 170knots at best? Burning 44gph? The max cruise delta on 850 starting at sea level is 86gph, TAS of 239, at FL180, 70gph, TAS of 289. So if the winds are really howling, you can stay at tree tops, and burn only a tad more fuel. But the wind delta has to be greater than 50knots between sea level and FL180 in order for it to make sense.

In a twin TP, you take a much bigger hit. They don't carry that much more fuel than a single, but you have two engines sucking the fuel, so instead of 22gph difference, you start talking about 44gph difference and that starts eating into available time aloft pretty quickly.

There is a big difference between SETP and TETP.

Now we got special air molecules that know how to impeded a twin more than a single.

In other words, outside of some extremely minor compressibility effects at these speeds, the effect of thicker air on the two aircraft will be the same. You aren't going to see one airplane lose 25% range and the other one lose 40%. That would imply an astounding asymmetric change in drag coefficient with altitude that just isn't plausible.

Mike C.

You do know that the SAME basic engine is on the TBM and KA350? PT6A-6x series.

I wonder how the engine knows to burn more fuel if it is mounted on a King Air? Pratt really has some interesting technology, some sort of "twin induced fuel consumption" sensor that burns more fuel if mounted on a twin.

In other words, your statement is bogus. Flying lower will have essentially the same effect on fuel flow and speeds for both aircraft, thus affecting range about the same.

Mike C.

I'm looking at 850 numbers. 86gph at sea level.

Actually, incorrect assumption and I actually gave you wrong numbers. Just pulled up a TBM 850 POH. 5000 feet, max cruise, 80, gph, 252TAS. What's the 421 doing there? 170knots at best? Burning 44gph? The max cruise delta on 850 starting at sea level is 86gph, TAS of 239, at FL180, 70gph, TAS of 289. So if the winds are really howling, you can stay at tree tops, and burn only a tad more fuel. But the wind delta has to be greater than 50knots between sea level and FL180 in order for it to make sense.

In a twin TP, you take a much bigger hit. They don't carry that much more fuel than a single, but you have two engines sucking the fuel, so instead of 22gph difference, you start talking about 44gph difference and that starts eating into available time aloft pretty quickly.

There is a big difference between SETP and TETP.

You are forgetting about flat rating.

Both the TBM and KA350 have basically the same engine core.

The TBM flat rates it to LESS power than the KA 350.

If you power back the KA350 to the SAME power (per engine) as the TBM is doing, then it has the SAME effect on range being low or high. Each KA 350 engine would be burning the SAME fuel as ONE TBM engine.

You are basically trying to say there is some fundamental lesser efficiency of twins but using the fact that Beech didn't flat rate as much to prove it. No dice. What you are seeing is just an artifact of flat rating the two airplanes differently.

The fact Beech lets you USE more of the engine power lower doesn't mean a twin is suffering some exotic new drag unique to it.

Mike C.

Oh, I don't think they are that far off at sea level, but let's say 180knots at 45gph, so $1.25 per nm at $5.00 a gallon for 100LL, or $1.36 per nm at $3.80 a gallon for Jet A. Actually not that much of a difference now, is it

Add 30knot headwind and a TBM is actually much cheaper.