Impressive comparison vs. POH

[replica17 0]

Does anyone have performance tables for climb and descent? We only have them for cruise but to make a good fuel calculation I need those as well...

 

Thanks!

[HawkDsl 50]

Looking around i found this... not helpful in that it didn't include a chart... have a look around here... I've seen links posted to POH's for the King Air C90B

 

 

[replica17 0]

Thank you. But I'm more looking for graphs so I can make a good fuel planner..

[fppilot 4,385]

Thank you. But I'm more looking for graphs so I can make a good fuel planner..

 

Fuel consumption is based on loaded weight, altitude, temperature, and speed. Try starting off with the recaps in this replicated text from the AOPA specs for the C90B:

 

"Fastest cruise speeds occur at lighter weights in the 16,000- to 20,000-foot range. With torque set just under redline and props turning at 1,900 rpm, true airspeeds of 249 kt can be realized on fuel burns of 88 gph, or 592 pph.For maximum range, fly higher. C90B performance tables say that at 29,000 feet you can count on 199 KTAS burning 45 gph, or 302 pph. Cruising at 26,000 feet, a pilot and four passengers can fly at 196 KTAS and cover 1,040 nm with NBAA IFR reserves — which include an alternate airport 100 nm from the destination."

 

Then you might want to register at a site like fltplan.com and sort through all that is available there. Be aware that site is real world, not flight sim, so be cautious with your use. You will need to use the IFR (Domestic format) for flight planning and make sure you do not file (real world). I use the site for my FSX flight planning and have several aircraft configured. Go to Edit Aircraft in the left column. You can find a C90 listed there. Set one up with a fictitious tail number. Once you have that done and saved (press here with done), you can then go to Aircraft Performance and that will show you the stored information for that aircraft type. It is listed per 1,000 ft of altitude. i.e. incredible detail. You can start with that, then fly and record your consumption, then come back and edit the performance, which only affects your own stored C90. Note that the C90 listed is not specific to A or B, so you will need to customize. I am so far finding that the Carenado FSX model burns less fuel than the specs on the fltplan.com site, so I am constantly revising my own stored performance.

 

Hope this helps!

[fppilot 4,385]

Here are two screenshots of tables from the web site I mentioned. The first one is my customized table I am working with. The second is the resident table that I started with. I do not know the origins of the resident table. It does not specify which variant of the C90 is was based on. I have done very little to change the climb or descent speeds. Mostly what I have done is taper the cruise burn to more closely match my experience with the Carenado modeling. You may also see that the Cruise TAS speeds in the table are low, or at least lower than what I am flying at but I have not adjusted that column of the table yet. I will then chase the climb and descent speeds and burns.

 

Using my working table I planned and then made a flight from Denver Centennial (KAPA) to Chicago Midway (KMDW) at FL250. Flight Plan trip length was 814 nm. In the actual FSX flight I added a STAR and approach that was not in the calculated flight plan, so it added time and distance. My plan was for 3:36 enroute and 1,764 lbs burn. My actual enroute was 3:44 with 1,636 lbs burned. The burn was 92% of plan (about 130 lbs lower than plan), and I flew at 25.000, IAS of around 170, and likely an OAT of around -20 to -30C, which should have put TAS a bit higher than the 220 knots in the table for that altitude.

 

Given that I was cruising faster I'd say that the Carenado model is clearly burning significantly less fuel than the resident table at the site. Over a 2 1/2 hour period of level cruise at 25,000 I logged a burn that averaged 486 lbs/hr. The resident table uses 422 lbs at 25,000. My experience a day earlier on a flight from Orange County Calif (KSNA) to KAPA was similar in burn performance at around the same altitude.

 

My working table:

 

The resident table I used for the starting point:

[fppilot 4,385]

I'd say that the Carenado model is clearly burning significantly less fuel than the resident table at the site.

 

I mis-stated that in my post above. What I should have said is that the Carenado model is burning less fuel from start to destination than the resident table at the planning site, and also still less than my own edited table. I have no idea how true to the model the resident table is, so I am making no statement whatsoever about the accuracy of the Carenado model. Just working toward a good match for flight planning for the model, which is what replica17 appears to be interested it as well.

 

I have some additional work to do, especially on climbs and descents. I find myself climbing at a somewhat less aggressive rate at lower altitudes, more like 1,500 per min., and at a more aggressive rate from 10,000 up, usually 1,000 per min. My flight from KAPA to KMDW started off fully loaded, which is also a factor.

[replica17 0]

Thank you fppilot, I will use that data as well and see how it works out!

[HawkDsl 50]

I hazard to guess that pilots of new C90's skew the chart a bit. Newer C90's are more fuel efficient then our C90B.

[fppilot 4,385]

I hazard to guess that pilots of new C90's skew the chart a bit. Newer C90's are more fuel efficient then our C90B.

 

Ahhh! But! With this Carenado model I still am burning LESS fuel, not more. So at first glance it would appear to be more efficient than that modeled at the flight planning site.

 

I did two things last night. First I downloaded the C90B POH linked in Benoit's message above in this thread. Then I completed a flight from KESN (Easton, Md.) to KAVL (Asheville, NC) and logged my fuel performance. I stayed faithfully on 1900 RPM and stayed with the torque settings from the POH chart for Maximum Cruise Power @1900 RPM for -30C. I varied my altitude with cruise segments at FL290, FL240 and 16,000. Interestingly my IAT varied from -29C at FL240 to -17C at 16,000. I did not make a note of the IAT at FL290.

 

So then I went back and looked at the resident table for the type on fltplan.com and started comparing it to the tables in the C90B POH. I found a match. The resident fltplan.com table matches the POH table for Maximum Cruise @1900 for 0 degrees C.

 

I still appeared to be burning about 8 to 10% less than fltplan.com projections, so I created my own custom C90B table from that resident table and reduced the burn for each altitude by 8%. I also reduced a burn factor for taxi and run up that appears elsewhere on that performance page but above the tables that you see in my earlier post. I then had the site calculate a new flight plan with the same route and it came out really close. Within 1%.

 

I took my own custom adjusted figures back to the POH charts for comparison. My figures compare closely with the POH chart for Maximum Cruise @1900 at +30C. My flight yesterday was at a "field level" temperature between the 0C and +30C. Now what I don't know is how much if any FSX allows a model, such as this C90B, to adjust burn based on temp, or to what extent fltplan.com's planning algorithms factor in real-world temperature in it's calculations.

 

Here is a view from yesterday's flight in N5590T at FL240 over South Boston, Va. (SBV VOR)