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Username ProtectedReally Frequent Poster
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07-19-2021, 08:33 AM #1Tankering Fuel - Rules of Thumb
I have a half-dozen flights under my belt in the new-to-me P300. I'm working to refine my flight planning criteria. For example, my operating cost per minute (EEC + ESP) vs. equivalent pound of fuel saved works out to be ~30lb/min (using $4.50/gallon). One planning item that rarely came up in the P100 is tankering fuel. With the P300 and the extra payload available tankering substantial amounts of fuel is now a reality. Obviously, carrying extra fuel and its associated weight comes at a cost.
For example, my next trip has six legs. One of the legs is short, requiring 3000lbs of fuel on board. However, the fuel is $0.72 cheaper than the destination and I'll need full tanks for the following legs. I can tanker 2000lbs of fuel if it makes sense; in this case, I think it probably does.
Has anyone come up with a rule-of-thumb on when tankering make sense? If not, has anyone calculated the extra fuel burn per lb of payload or some other figure I can back into a tankering algorithm? -
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07-19-2021, 01:46 PM #2(Username Protected),
Congrats on the 300! Make sure to update your profile to Phenom 300 Owner & Pilot.
In regards to tankering, I take as much fuel as the conditions call for and the fuel price. Based on my experience the extra weight doesn't materially affect the fuel burn and time.
For example, on a 446nm flight I did recently (PIE to CLT):
Departing with 3000 lbs of fuel
Flight Fuel 1850 lbs
Fuel at Landing 1200 lbs
1:09
Departing with 5310 lbs of fuel
Flight Fuel 1876 lbs
Fuel at Landing 3434 lbs
1:11
+2 min, +26 lbs of fuel
In the beginning I only took enough fuel to land with ~1200 lbs or so, but that was causing me unnecessary stress for unplanned slower climbs, earlier descends, holds etc. Recently I always take more fuel than needed to alleviate fuel as a concern (unless I do a max duration flight like PIE - SLC https://flightaware.com/live/flight/...400Z/KPIE/KSLC) -
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07-20-2021, 10:55 AM #4I operate similar to how (Username Protected) does. I haven't done the comparison like he outlined, but I agree, there isn't a drastic difference in consumption for heavier weights and the economics I think typically favoring the cheaper fuel.
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07-20-2021, 12:53 PM #5https://www.flightdata.com/flights/N329MC/2329716
Max Cruise and about 20 kts on the nose. ForeFlight calculated 4233 lbs (landing 967 lbs), ended up burning 4430 lbs (landing 770 lbs) due to earlier descent etc and SLC was landing south which adds at least 10 min flying time vs joining final right from the arrival. The most I can typically get is 5200 lbs, not the book 5310 lbs.
I target 1200 lbs at landing, but for VFR and multiple runways at destination will go as low as 750 lbs. That is 45 min at 150 kts, which is incidentally also 45 min of fuel at 430 kts at FL450.
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07-20-2021, 08:36 PM #6Thanks (Username Protected). We bought the P300 in order to make the SLC run non-stop from Charleston. My daughter and son-in-law just moved to SLC for her residency so we'll be making quite a few trips over the next three years. Today FLTPLAN says 4325lbs from CHS; which sounds like that may be a bit tight unless VFR. We fly to SLC from Holland MI on Sunday and that is calling for 3750lbs which should be no issue VFR or IFR.
Have you tried filling from the single-port and then putting fuel into the over-the-wing fuel caps to see if you can squeeze in 200lbs? The line guys won't like it but a cash tip makes things OK. Anyone tried this? Does it yield a benefit? -
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07-21-2021, 07:50 AM #7I’d advise against the method of SPR followed by the pulling caps. I’ve seen someone attempt this and there was already enough fuel to push the cap off when they popped the tab and fuel ran out everywhere. Sorta of depends on how level the jet is sitting when it’s filled. If you’re in need of the absolute capacity, then overwing it from the start. Just my opinion, but it’s cutting it too close if you have to try to get that extra 100-200lbs to make it work.
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07-21-2021, 09:01 AM #8Yep that is exactly what happens. I was at LAS early last year and was parked at a slight slant, so the single point fuel system kept closing the valve early for some reason on the higher wing. Thinking I was clever I opened the cap to add more fuel on the high side and fuel just streamed out. The fuel cap is closer to the wing root, instead of the empty compartments further at the tip.
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07-21-2021, 09:53 AM #11I log every flight using the G1000 data logger and upload the data to FlightData.com (a service I created back in 2008 and sold a few years back). I picked a handful of flights of where I know we topped off and compared it to the OAT sensor value (which reads a bit high when on the ground).
Data points on 16 flights. Low of 5159 lbs to a high of 5340 lbs.
Sample data for one flight
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07-21-2021, 10:03 AM #12To get the most fuel into the tanks you need the 50psi of pressure refueling. It helps slightly to have the nose downhill if you can manage that. If you open the caps after topping off it will pour fuel out. Tankering cheap C.A.A. fuel will always out way the extra weight at cruise. Enjoy your 300 and let me know if I can ever help with any flights! I am a full time contract/mentor pilot on both Phenoms with over 12 years of experience on them.
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