Safe Endurance M20B 180 HP?

[bruceyung]

Hello friends,

Coming back once again to hear from you all.This time regarding B models endurance. For B model owners what would be a safe endurance at 9,500-10,500 ft with correct leaning? Iv never flown more than 2 hours in my B model.Would like to know whats safe to fly, can a B fly 380 NM on its MTOW , top off and considering a 10kt headwind?

 

thankyou my friends

Fly Safe.

[cliffy]

Have you ever done a fuel burn check on your airplane?

Fly one hour on one tank, switch to the other for one hour, land and refill to check fuel burns. Go 2 hrs on the first tank the next time and an hour on the other and refill. Do that for 25 hrs of flying and you'll have a pretty good idea of what you can do. 

On my D with the 180 HP engine I know from much experience and testing that I can ball park the burn and be pretty accurate at  10 gallons the first hour, 9 the second and 8 every hour there after, at the power setting that I use all the time.  So that gives me 5 hrs flying (10+9+8+8+8=43 burned with 8 for reserve) ON MY AIRPLANE! I don't do 5 hour legs anymore either. 

As a quick check for your airplane look at your Owner's manual for fuel burn and then be very conservative until you have hard numbers from experience. 

[rbridges]

I wouldn't go by distance, I'd go by time.  I'm ashamed to ask, but isn't the B model a 180 HP, 48 gallon plane?  Just a rough guess, but I'd think you'd have 4+ hrs of endurance, but I would definitely do like cliffy recommends and find out a more exact number.

[Hank]

Fly by time, not by distance. Fill up after every flight until you learn how your plane performs. My C has 52 gallons, and I've flown over 4-1/2 hours twice, landing with 10-12 gallons each time. But what are YOUR power settings? How do YOU lean? What is the demonstrated burn rate in YOUR plane? Thats all that matters . . . What someone else's plane will do doesn't matter, just like with speed.

[astravierso]

As has been stated you should work out the numbers that are actual for your AC. With that said in MY "B" (48 gal ) I plan for 10 gal/hr as a rule of thumb @ 65-75% power between 7.5K and 11.5K (Mountain West Flying in the US) which give me 4 hrs with me a 48min reserve. I usually do better than that (8.5-9 gal/hr). Besides I have no interest in flying for any longer with out a break.

Cheers

[Alan Fox]

My B burned about 12 gallons per hour at 23 24 (sea level) , and the stock B holds 48 gals probably 46 usable.... it would settle in at just about 160 MPH indicated ... Had speed mods   I would guess  3 hrs to 3.5 hrs depending on alt and power setting...

[Hector]

I have a C with 180hp and JPI with fuel flow. At my typical cruise setting of 22/2400 I can comfortably fly for 4 hours and still have a little over one hour of fuel on reserve. I work the tanks such that most of the one hour reserve is on one of the tanks


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[TTaylor]

My early C with 48 gallon tanks was a good four hour plane in the west at 9 to 12 K.  Use the standard O-360 leaning technique of lean till rough and then enrich just to smooth.  I would average 9.5 gph or 38 gallons for 4 hours.  This leaves 8 useful or 10 total as reserve. With no wind this should give you nearly 520 nm range. 

 

[carusoam]

A few ideas have been shared...

1) you can determine the fuel burn for your plane.  Fill, fly, refill, take notes... repeat a few times...

2) FF is dependent on power setting and mixture.

3) M20B tanks are a few gallons less than the M20C.  The C got nicer, low volume wasting, fuel cap systems.

4) It is important to know the fuel burn for...

  - taxi and take-off

  - limb

  - cruise

  - descent and landing

5) Leave an extra hour in the tank beyond the usual safety volumes required for VFR and IFR flights, until you have comfortable numbers.

6) Strive for accuracy.  Because you can determine it yourself.

7) know how accurate your fuel level indicators aren't.

8) learn how to stick the tank.   Build your own stick for this.

9) know that there are tools to improve the situation you have.  (Budget dependent, worth it!)

  - engine monitors. 4CHTs, EGTs and carb heat

  - digital fuel level floats

  - my favorite, a FF indicator.  Get one! 

10) Rough cruise FF is about 10gph,  Climb FF is about 15gph.  Leaning using the EGT to determine °ROP.

11) Consider getting a copy of the latest version of the C's POH.  It is full of useful data that wasn't available when the C's older brother (B) was built.  It was written around 1977 or so...

Running out of fuel over a tropical forest would make it incredibly hard to be found.

PP Ideas I collected on MS, here...  I have visited Sao Paolo a few times...

Best regards,

-a-

[TTaylor]

I agree with Carusoam that a fuel flow system is one of the best investments for peace of mind for long flights. I would not want to fly without one now.  I have checked mine extensively so that I can trust it for long flights.  Nice to know how long you can fly. My F with 54 gallons can travel over five hours with reserve when leaned to 8.6 gph at about 139 knots. 

I never trust the fuel gauges and would use the one hour tank switch method for getting a good idea of fuel available.  Start on one tank and fly for one hour, switch to the other tank for one hour.  Switch back to the original tank until it runs dry.  That time is a good estimate (slightly conservative because you climbed on the first tank) of the time you have left if you don't change cruise settings.  I flew 528 nm with comfortable reserve in my C. 

[BJM61]

I have a 61' B and always used to wonder the same thing. So after doing lots of testing over the years we had the fuel burn down prettty well. Climb/Takeoff would burn about 11 to 14 gph. Then anywhere from 7.5 to 12 gph depending on loading, power setting, and cruise level. Once that was confirmed we needed to confirm that all 48 gals were useable as stated in the poh. Using the the fuel pressure gauge and our timing we were able to empty 1 tank and switch before any engine shutters. Long story short all 48 gals are useable and at 8 gph you can go 5(+) hrs or 700(+)nm with an hour reserve. We can go from our place in Colorado to just outside of Houston(728nm) nonstop, with the vfr reserves. Can't get there from Houston nonstop because of the climb. Since then we have added a JPI with FF and it confirms everything, including how far off our fule gages are. Best upgrade we have done, really helps finding peak for leaning purposes.