You guys think my F is too slow.

[David Mazer]

In another thread several other F drivers noted they felt my F was too slow.  I'm trying to figure out why.  I've attached a few pictures of things I feel might be creating more drag than other F's out there and would appreciate comments on the likelihood these may actually be the culprit.  Sorry about some of them being sideways.  Thanks.

 

Two of these antennas:

 

The overhead vent closed and opened:

 

Various belly protrusions:

[Hank]

How smoothly do your gear doors close? Does a main hang down a couple of inches? Mine did in winter and would cost me 10-15 mph until it popped up. Hasn't recurred since replacing my 1969- vintage pucks (I misread it upside down as 1996!). Are your nose gear doors original, or the improved overlapping doors?

Check operation of cowl flaps. How far are they open in trail? Do they close completely?

What are your power settings? How do you lean?

[Shadrach]

I'll see all of those protrusions and raise you a cloths line starched from tail to cockpit attached to my (soon to be removed) ADF.

Seriously though, a stock F should be 150kt airplane (+/- 5kts depending on weather and aircraft condition).

[Ragsf15e]

Ross has a fast F, don't listen to him.  Mine is a 1968 with a 700 SMOH engine (15 years ago) and minimal antennas.  I can get 144 KTAS at about 5,000' if I fly WOT, 2500 RPM, and 100 ROP.  Generally I fly higher and at peak or LOP.  I'll see around 135 KTAS.

 

You've got to do a GPS based 3 or 4 leg test to figure out your speeds - don't use your airspeed indicator, temp, etc to figure that stuff out - too many errors and unknowns.  Go run a 3 or 4 leg test.  I'll post a link to a previous thread with lots of speed numbers for F models below.

 

Rags

[Ragsf15e]

Heck, I can't make it post a link right now... search for "M20F speed checks" and you should find it... someone help me out with a link!

[Marauder]

In another thread several other F drivers noted they felt my F was too slow. I'm trying to figure out why. I've attached a few pictures of things I feel might be creating more drag than other F's out there and would appreciate comments on the likelihood these may actually be the culprit. Sorry about some of them being sideways. Thanks.

Two of these antennas:

2015-03-24 16.43.09.jpg

The overhead vent closed and opened:

2015-03-24 16.44.25.jpg

2015-03-24 16.44.42.jpg

Various belly protrusions:

2015-03-24 16.45.50.jpg

2015-03-24 16.46.02.jpg

Like Ross, my F is a solid 150 KTAS airplane. As for your pictures, yep, got/had all those. The antenna you have are called the 600 knot antenna and I had 2 before my avionics upgrade. I have the little gap on the vent and the breather/drain tubes for the battery that you show.

If you haven't had the plane checked for rigging. At one point I was 5 knots slower and found I had a gear door slightly opened and stupid mechanic who fixed the flight turning tendency but adjusting the aileron rigging to compensate. A little flap drag will also cause issues. Without any speed mods, you should be closer to 145k ROP.

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[TTaylor]

I flight plan for 139 knots LOP at about 8.5 gph at 10,000 feet. I might get 144 knots if I pushed up to 10.5 gph, but why waste the fuel? Stock 1975 F with flap seals and three blade prop. See the Mooney evaluations on-line for similar numbers. I would love to see 150 knots at 9.0, but I will need a 201 window mod, remove the step, and other mods to get there.

[David Mazer]

I'll start looking into these suggestions next week as I'm actually working (I hate the thought) too much this week and won't have time.  This F is a 3 blade and I usually run WOT, 2400 RPM, 50 degree ROP at 6,000 to 8,000.  My JPI 900 shows high 60s for %HP.

[1964-M20E]

Mine maybe slow too but I plan for 145kts usually 2450 @ 8.5GPH 22 to 23"MP and when I do flight planning the times come up really close.  I have never done a test to find my TAS.  My F has many of the mods, flaps seal, aileron seal, 201 windshield cowl closure etc everything but the 201 cowl, newer nose doors and inner main doors.  The rigging is all within specs.

[FloridaMan]

Have you inspected your camshaft for wear? Read the caption for the top-right picture here: http://cujet.com/html/engine.html

[M20F]

Have you inspected your camshaft for wear? Read the caption for the top-right picture here: http://cujet.com/html/engine.html

Second this a lot of speed variances are caused by the engine just not making the right power versus drag. We always tend to focus solely on drag items. Have to look at both.

[MyNameIsNobody]

Get a cowl closure and a speed slope windshield. Try flying at higher RPM and Peak EGT. Clean your belly. Only fly when you have a tailwind...

[M20F-1968]

Mine is with many mods and turbo-normalized.

At 9,000ft it is a solid 158-160 kt airplane.

At 17,000 a 170 kt airplane, better at 18,000 ft, but it took lots of work to get it there.

 

John Breda

[Danb]

john..that's pretty quick..

[Shadrach]

Ross has a fast F, don't listen to him.  Mine is a 1968 with a 700 SMOH engine (15 years ago) and minimal antennas.  I can get 144 KTAS at about 5,000' if I fly WOT, 2500 RPM, and 100 ROP.  Generally I fly higher and at peak or LOP.  I'll see around 135 KTAS.

 

You've got to do a GPS based 3 or 4 leg test to figure out your speeds - don't use your airspeed indicator, temp, etc to figure that stuff out - too many errors and unknowns.  Go run a 3 or 4 leg test.  I'll post a link to a previous thread with lots of speed numbers for F models below.

 

Rags

 

 

Maybe, I'm all wet. I'm certainly not flying the best instrumented F.  I pass my pitot static tests.  Below 2000ft on a cool day WOTRAO @2500 RPM and 25LOP  the IAS runs in the yellow (starts at 152Kts) hottest CHT is hard pressed to get above 325.  I know what the forecast winds at alt are and I'm typically right where I should be in terms of ground speed often better.

 

I've made several GPS speed runs at 4500ft over the years and they have varied from 148 to 153.6kts (IIRC) depending on weather. I also did a speed run at 13,500 that yielded 143kts (we were light).  I do better than book sometimes, but the book does not allow for leaning below 75%.  While my airframe does not have a lot of fancy glass, my engine is fully instrumented and I promise that I will never run full rich at 7500 ft and 23" as the book suggests. My book actually says to run full rich at 10,000ft at 21" and 2700rpm.  I think that's poor SOP.

 

A few years ago on a return trip from N68 to KHGR (only 16NM as the crow flies) I informally raced a Comanche-180. He departed before me and was on his downwind when I strated my take-off roll (one must back taxi at N68). I could here the disappointment in his voice when after we both called tower at about 8 miles out, she told him that I was "overtaking".  

 

My hangar neighbor flies a Comanche 250. He's an old school 25 squared kind of a guy.  On a few of the short runs we've made down low, I run as near to him as makes no difference.  It's been said in several articles that Air Facts magazine lined up an M20E againts a PA24-250 back in 1964 and ran them head to head on the deck above the Chesapeake Bay (as I recall).  The 200HP plane walked away from the 250Hp airplane. I have looked for the issue, but have yet to find it.

 

Anyway, age, ownership and multiple mechanics can have a weird effect on an airplane.  Ours is pretty much unmolested as it's been in the family since it was purchased in 68 from Henry Weber Aircraft (it was the dealer's demonstrator and had a few hundred ours on the tach). It's light at 1689lbs empty, it's totally stock including the 47 yr old paint (always hangared when not traveling).  I take great care to ensure everything closes as it should. I personally hung the engine and all that went with it (under supervision).  I took special care with rigging the cowl flaps.  I keep an eye on the rod ends on the gear doors, if any one of them seizes, it will cause any number of problems with the gear doors that you cannot feel from the cockpit.

 

My father used to file for 145Kts back when he flew it regularly.  He has not flown it in 3 or 4 years, but he noted right after the most recent engine install (2009) that it runs smoother and stronger than it ever has.

 

I contend that 140kts is on the slow side for an F. 130kts would have me looking at the gear doors and the rigging. 130KIAS is nice, gentle, cruise climb up to about 5000ft..

[Marauder]

john..that's pretty quick..

Take a look at his gallery. That ain't no F... That is a J disguised as an F.

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[MyNameIsNobody]

Mine maybe slow too but I plan for 145kts usually 2450 @ 8.5GPH 22 to 23"MP and when I do flight planning the times come up really close.  I have never done a test to find my TAS.  My F has many of the mods, flaps seal, aileron seal, 201 windshield cowl closure etc everything but the 201 cowl, newer nose doors and inner main doors.  The rigging is all within specs.

They are all "slow" if you are burning 8.5gph...

I see all this "planning"....

Do you SEE 145kts at those settings? If Yes, your plane is NOT SLOW. You are flying it SLOW. Which is A.O.K.

[Lood]

My '67F is stock, except for the Lasar cowl closure - which did nothing to increase the speed of my airplane, btw. I scored 4kts with my new engine and overhauled prop and at 6500', WOT, 80 deg ROP, 2500rpm, I see 142kts TAS. I plan all flights at 135kts and I usually beat that by about 4kts.

 

I went through many years' results from our annual Presidents Trophy Air Race, where everybody's single goal is to fly their airplanes as fast as possible. All the pilots take every possible step to polish, loose weight, I mean everything to get the airplanes as smooth as possible and to gain every possible knot. From these results, the flat out speeds of M20F Mooney's, according to the loggers they carry, is 140kts - 148kts. I must add though that I don't know of any local F's that have any speed mods. Most local F models seem to have an average maximum cruise speed of around 144kts.

[MyNameIsNobody]

Are these indicated (ASI) numbers or Ground Speed?

[Shadrach]

I indicate more than 150KTS below ~3500.  However, I believe my ASI is likely a bit optimistic. 

[Shadrach]

Are you guys seeing lousy climb performance as well?  I was messing with my new GoPro last weekend. It was not until I went back and looked at the footage and the timer that I realised that I crossed 1000ft almost exactly 1 minute after opening the throttle. It was pretty close to ISA, maybe a tad cooler with me (190lbs) and my wife (125lbs) and 230lbs of fuel.  Considering that I was not shooting for Vy (it was bumpy as hell). I think that's pretty extraordinary for a 200hp aircraft.  I plan on doing more with the GoPro this weekend.

[David Mazer]

I think climb is pretty anemic but I was used to the climb in a Rocket.  You know, point the nose up, sit back, and look at the sky until you reach your desired altitude.

[Marauder]

Are you guys seeing lousy climb performance as well? I was messing with my new GoPro last weekend. It was not until I went back and looked at the footage and the timer that I realised that I crossed 1000ft almost exactly 1 minute after opening the throttle. It was pretty close to ISA, maybe a tad cooler with me (190lbs) and my wife (125lbs) and 230lbs of fuel. Considering that I was not shooting for Vy (it was bumpy as hell). I think that's pretty extraordinary for a 200hp aircraft. I plan on doing more with the GoPro this weekend.

You might be onto something. Mine climbs around 1200 FPM in the winter and around 800 FPM in the summer at Vy+10.

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[Lood]

Are these indicated (ASI) numbers or Ground Speed?

 

Sorry, these numbers are ground speed, measured by the GPS loggers. My F normally indicates between 120kt - 125kt or around 135mph - 140mph.

 

I could definitely feel the take off and climb performance increase after my prop was overhauled. My home field is at 4000' ASL and when I'm alone, I see around 800ft/min, climbing at around 110mph IAS, WOT, 2700rpm, target EGT. Fully loaded, I see 300 - 400ft/min.

[Shadrach]

You might be onto something. Mine climbs around 1200 FPM in the winter and around 800 FPM in the summer at Vy+10.

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I'm beginning to think that I just have an engine that's on the upper end of the spectrum. We're in the same neighborhood in terms of climate and climb rate. I shoot for 105kts on initial climb. If I'm leveling off under 4K I'll climb at around 120kts.