1968 M20C TAS

[LevelWing]

I'm looking at purchasing a 1968 M20C and the owner says that he always plans for about 125kts TAS but usually gets higher than that. That seemed a little low to me so I looked up the POH (found this one). At 5,000', 2500 RPM and 22" MP, that's still 156 MPH or about 135kts. What is a realistic speed range I should expect to get (with wind not being a factor)?

[Hank]

My 1970 comes pretty close to book speed. I have pictures indicating 133 mph at 10,000 msl. (133 + 2% per 1000 = 133 +20% = 133 + 27 = 160 mph at ~20"/2500.

But I have the 201windshield, guppy mouth closure and 3-blade prop.

[BigTex]

I'm looking at purchasing a 1968 M20C and the owner says that he always plans for about 125kts TAS but usually gets higher than that. That seemed a little low to me so I looked up the POH (found this one). At 5,000', 2500 RPM and 22" MP, that's still 156 MPH or about 135kts. What is a realistic speed range I should expect to get (with wind not being a factor)?

I cruise all the time at 5500' at 2400 rpm and 21" mp at 150 mph. If I push it at all I would cruise well into the yellow.

[Oscar Avalle]

I cruise 135 mph indicated at around 10000 feet too. But I have the 201 windshield and many other mods.

[Z W]

My 68C with all the speed mods and a 3 blade prop did 140-145kts true at 7k-9k ft. Honest flight planning. Lower or higher altitude and true airspeed would decrease. It would also vary with outside air temperature and gross weight.

Some do a little better, some worse, but 135-150kts true seems to be normal for a C model.

[Hank]

I cruise all the time at 5500' at 2400 rpm and 21" mp at 150 mph. If I push it at all I would cruise well into the yellow.

Last weekend I was indicating 150-153 at 5500, running 21 or 22"/2500 (I don't remember exactly). That's still 11% or 16 mph to add in, putting it at 165 mph or better. Nice tailwinds made for 170 knot ground speed outbound!

[TTaylor]

My 63C would do 135 knots at about 9 to 9.5 gph with no mods at 8 to 12k. . I flight planned for it and was nearly right on all the time. A stock C should do that without any trouble. My 75F will do 138 knots at 9 gph with almost no mods. Looking forward to a 201 windshield some day.

[DanM20C]

My only mod that might affect speed would be a Simitar 2 blade prop.  Otherwise my C is stock.  My true airspeed averages 141kts when I cruise between 9-11k .  If I stay low (5k and below) I will only see 135kts If I maintain 75% power.  If I fly 25/25 down low it will creep up to 147kts but the fuel burn would be closer to that of a Bonanza. 

[kujo806]

So it sounds like M20C's are only slightly faster than the arrow I have been flying.  I was surprised by that, but I don't usually hear of arrows that come close to their book speed either.  I can get 140kts true in the arrow although I don't usually flog it quite that hard.  I can do 135kts at 9.5gph quite easy however.  It has the 2 blade scimitar, and I have heard that makes a big difference.  I guess I will have to look for at least an E if I want to move up in speed.

[N33GG]

Stock 68 C except Scimitar two blade prop.  Consistently get 143 kts tas, plus or minus a knot or two, running 23-24" at 2400 rpm between 5500' and 7500'.  Overall, 143 kts tas seems to be the number.

 

Could never get close to 140 kts with the 3 blade that came with the plane when I bought it.  Scimitar made a lot of difference.  The 3 blade was superior for take off and climb, but the Scimitar is superior for cruise, at least with this aircraft... I chose cruise performance.

 

FWIW and YMMV

[DanM20C]

So it sounds like M20C's are only slightly faster than the arrow I have been flying.  I was surprised by that, but I don't usually hear of arrows that come close to their book speed either.  I can get 140kts true in the arrow although I don't usually flog it quite that hard.  I can do 135kts at 9.5gph quite easy however.  It has the 2 blade scimitar, and I have heard that makes a big difference.  I guess I will have to look for at least an E if I want to move up in speed.

 

Do you own the Arrow?  I love Mooneys, but for me the hassle of selling the Arrow and finding/buying a C or E isn't worth the marginal increase in performance.  Now if you were looking at picking up a J that would be a different story.

[Mooneymite]

I have a '74 C model, no speed mods what-so-ever.  I consistently get 135 TAS and 9 GPH (block to block on trips 1 hour, or more.).  I've had the plane for 15 years and have a lot of performance history to validate this.  Obviously any given flight will vary slightly due to atmospherics, but "on average", 135 TAS and 9GPH.

 

 

I've got time in a 200HP Arrow and never got close to 135 at Mooney fuel flows.

[carusoam]

What are you trying to do???

-a-

[kujo806]

Do you own the Arrow?  I love Mooneys, but for me the hassle of selling the Arrow and finding/buying a C or E isn't worth the marginal increase in performance.  Now if you were looking at picking up a J that would be a different story.

 

I'm in a partnership on it.  I have been lurking on MS since my PPL training and always liked the efficiency of the Mooneys.  That is why I was surprised to see real world M20C cruise speeds that are marginally better than what I am getting now.

What are you trying to do???

-a-

Well right now, the arrow partnership is probably the best fit.  I don't get to fly nearly as much as I'd like to due to work/wife/baby responsibilities.  I would definitely like to move up at some point and get my own plane in the near future.  I have had a few opportunities, but I haven't been able to justify it or things fell through.  At this point, I think I have narrowed down my choices to NA Mooneys or Debonairs...apparently a M20E or better if I want a decent increase in speed.

 

I have a '74 C model, no speed mods what-so-ever.  I consistently get 135 TAS and 9 GPH (block to block on trips 1 hour, or more.).  I've had the plane for 15 years and have a lot of performance history to validate this.  Obviously any given flight will vary slightly due to atmospherics, but "on average", 135 TAS and 9GPH.

 

 

I've got time in a 200HP Arrow and never got close to 135 at Mooney fuel flows.

Like I said, I haven't heard of too many arrows that do get book speeds, but I can attest to the fact that mine can touch 140kts.  At 140, I would not be at 9-9.5gph however.  I do typically cruise at 135kts though, and verify how much fuel I put back into it after the flight.  At 135, it burns about 9.5gph or slightly less.  The other partners have stated that the new scimitar prop added several knots to the cruise speed.  I was not in the group at the time of the prop change.

[Mooneymite]

 At 140, I would not be at 9-9.5gph however.  I do typically cruise at 135kts though, and verify how much fuel I put back into it after the flight.  At 135, it burns about 9.5gph or slightly less.  The other partners have stated that the new scimitar prop added several knots to the cruise speed.  I was not in the group at the time of the prop change.

 

 

Gotta be careful comparing fuel flows.  My 9 GPH is "block to block average", not the fuel flow at 135 kts.  Typicallly, cruising at 135 I'm burning less than 9 depending on atmospherics.  The Arrow burns more in the MPG category than the Mooney in my (very limited) experience.  YMMV.

[N33GG]

Unles you get an E with 201 windshield and cowl, don't expect a vast cruise speed increase over the C.  FYI, FWIW, and YMMV

[Mooneymite]

Unles you get an E with 201 windshield and cowl, don't expect a vast cruise speed increase over the C.  FYI, FWIW, and YMMV

 

 

Actually, unless you step up to a jet, there won't be a vast increase in anything!  

[Hector]

I have a 67C with a few speed mods except the 201 windscreen. I get 142 Kts at 7500 running 22/2450

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