M20F w/201 mods

[Tx_Aggie]

Earlier this year I posted questions on flying a C model offered to me by a local pilot who wanted his C model running. He has the problem owning Both TBM and a 1967 M20C and wanted me to keep the C flying for a season only paying for gas. It was great while it lasted! He's selling the C, but I've since found another opportunity with a similar deal structure on a 1970 M20F with the 201 windshield and a certain kind of cowling closure. Not the one I had in the C that covers the bottom engine inlet, but one that looks like a modified version of the 201 style cowl but slightly different... if that makes sense. This airplane doesn't have up to date IFR equipment but has a wing leveler and a newish Garmin panel mounted VFR gps- I'd have to check again to see what kind. My question is what to flight plan TAS for. He says the only thing different from his plane and a normal 201 is the one piece belly, so in my opinion, knocking 1-2 knots off, can I expect to plan on 152-153 KTAS? Or should I plan closer to 145-150? When I asked the question in the C, then flew the airplane on the cardinal heading test I found that 138 KTAS was better to use than the 142-144 KTAS others were telling me.
 
 
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[mike_elliott]

If the F is a fast 1970 F, you can figure on 145, if it is draggy or out of rig, 140

The cowl closure is probably an ARI closure.

[MyNameIsNobody]

Let the tails of speed begin.  What fuel flow did you fly in C?

[TTaylor]

With a 201 windshield it is likely about 145 kts at about 9 gph.   You can start conservative and use higher numbers if it is doing better.   Our 75 will do about 140 at 9 gph with almost no mods.

Let us know what you find.

[kpaul]

15 minutes ago, TTaylor said:

With a 201 windshield it is likely about 145 kts at about 9 gph

I average 143 ktas in my 75 F at 9 gph.  The only speed mod it has is the lower cowl closure.

[Tx_Aggie]

Let the tails of speed begin.  What fuel flow did you fly in C?

I could get 138 KTAS at 9000', just over 9 gph, usually cowl flaps wide open,

 

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[Tx_Aggie]

It's not letting me edit my post. But 9 gph, cowl flaps open, less than 380 CHTs at 8-9000'. Above 9000' I could partially close the cowl flaps depending on the fuel burn, my #2 cylinder was always hottest - far above the others.


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[Shadrach]

Stock F is a 150kt bird a good one will do a bit better. Without pictures, no one can say much...other than it ought to do about 150kts

[Tx_Aggie]

This was posted on flight aware from the previous owner I believe. Maybe he's here who knows. But this is the type of cowling I'm talking about.


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[Marauder]

This was posted on flight aware from the previous owner I believe. Maybe he's here who knows. But this is the type of cowling I'm talking about.


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That’s an ARI cowl. TTaylor, kpaul and I all have 75F models. I have the 201 windshield, gap seals and the lower cowl enclosure. At normal cruise, I flight plan 150 but will typically see 152. You should be in this area for speed.

If you push it, you can get closer to 155 but your fuel burns will be higher. And if you really push it...




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[mike_elliott]

8 hours ago, Shadrach said:

Stock F is a 150kt bird a good one will do a bit better. Without pictures, no one can say much...other than it ought to do about 150kts

depends greatly on year, twisted wing, etc...not all F"s are the same. A stock 1970 F would dream about 150, but not do it.

[wcb]

I actually think that was the older SWTA cowl mod.  I think the ARI mod looks more like the J.  Like the SWTA windshield mod the cowl mod is no longer available, but a nice mod.  I am in Houston with a 76 F and would love to add those mods to mine.  3 Blade prop, 201 Spinner, Cowl Mod and Windshield mod will hopefully be in the budget next year.  This year is on the panel for me.  Would love to see it sometime to compare.  Are you buying it from him or just getting some time in it?

[TTaylor]

At 9000 feet you should not be having issues with CHT.  I would check the baffling to see if something is missing or obstructed.   The cowl flaps open will slow you down a few knots.  Also some claim that the three blade is slightly slower.  I have the same prop, I like the smoothness and climb.   Altitude and fuel burn will affect your TAS.  I fly LOP and at about 9 GPH at 8500 to 11500 most of the time.  I could go faster by a few knots but at 2 to 3 GPH more fuel flow.  Read the MAPA review series on the C through J models.  It gives very honest numbers on each models performance at 50 degree ROP.  I would love 150 knots at 9 GPH, but I need a 201 windshield, new cowling closure, inner gear doors, and maybe remove or fair the step to get there.  All in time.

[Marauder]

It is definitely an ARI cowl mod. The now defunct SWTA cowl mod is much more than just an add-on and more closely resembles the OEM 201 cowling, in my opinion. 

Hopefully Bob Belville will chime in. He has the ARI cowl.


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[wcb]

@bluehighwayflyer you are 100% right.  I had the two mods backwards in my head.  That is the ARI.  Infact I think ARI might have even used that plane in one for the pictures they sent me as examples they did.  It was the exact same colors, but prior to 3 blade prop and windshield.  I have spoken with SWTA and they are supposedly trying to resurrect their mods.  However,  I sure would like the LoPresti (Crazy Price Tag) or SabreMechs Mod (still waiting on cost and performance numbers from them).

[Browncbr1]

Aside from the TopProp, my 67F (twisted wing) is stock and generally trues out between 147-143kts @ 65% power between peak and 25LOP  near gross weight on ~8.5GPH ,,... depending on weather conditions...I can see clearly that my wing and tail are out of rigging though... 

Straight wing with windshield and cowl should be able to go 150ktas no problem I would imagine.

[Shadrach]

6 hours ago, mike_elliott said:

depends greatly on year, twisted wing, etc...not all F"s are the same. A stock 1970 F would dream about 150, but not do it.

I have a box stock 67 "twist wing" (sopposedly slightly slower than the rest) and it will do 150kts all day long below 8K.

[Tx_Aggie]

I have a box stock 67 "twist wing" (sopposedly slightly slower than the rest) and it will do 150kts all day long below 8K.

What do you mean by twisted wing and rigging??


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[N6758N]

1 minute ago, Tx_Aggie said:

What do you mean by twisted wing and rigging??


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Model year 1967 F models had the outboard 1/4 of the wing twisted (wash in) for supposed aerodynamic and slow speed improvements. They only made them for one year.

[podair]

another twisted M20F owner, completely stock apart from 3 blade Hartzell. I routinely get 143-145 kt tas 9000ft at 8.5 gph leaned peak/slightly lop, usually 2500rpm 22in or so wot. Slower than the exaggerated 1967 poh but not bad. I m looking to do the lower cowl closure and 201windshield at some point, mostly for cosmetics but hope to pck up a few kt too!

[Hank]

3 hours ago, podair said:

another twisted M20F owner, completely stock apart from 3 blade Hartzell. I routinely get 143-145 kt tas 9000ft at 8.5 gph leaned peak/slightly lop, usually 2500rpm 22in or so wot. Slower than the exaggerated 1967 poh but not bad. I m looking to do the lower cowl closure and 201windshield at some point, mostly for cosmetics but hope to pck up a few kt too!

I hope you pick up speed! My C has these two speed mods only, plus a Hartzell 3 blade, and I generally true out at 146-148 knots.

[Guest]

3 hours ago, N6758N said:

Model year 1967 F models had the outboard 1/4 of the wing twisted (wash in) for supposed aerodynamic and slow speed improvements. They only made them for one year.

Isn’t the 67 F Mooney wing given “wash out” reducing the angle of incidence allowing the outer portion of the wing to stall later than the root.   “wash in” increases the angle of incidence causing the tip to stall first.

Clarence

[Browncbr1]

5 minutes ago, M20Doc said:

Isn’t the 67 F Mooney wing given “wash out” reducing the angle of incidence allowing the outer portion of the wing to stall later than the root.   “wash in” increases the angle of incidence causing the tip to stall first.

Clarence

Correct, washout is lower incidence at the tips (angled down compared to root)

[N6758N]

13 hours ago, M20Doc said:

Isn’t the 67 F Mooney wing given “wash out” reducing the angle of incidence allowing the outer portion of the wing to stall later than the root.   “wash in” increases the angle of incidence causing the tip to stall first.

Clarence

You are correct, I always get them mixed up. 

[Bob_Belville]

21 hours ago, Marauder said:

 

Hopefully Bob Belville will chime in. He has the ARI cowl.


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Mine is the ARI done in 1997. (1966 M20E) Judge for yourself but it looks to be the same to me.