Optimizing a C (D conversion)

[MooneyNoob]

Hi all,

I'm thinking of getting a C... Really a converted D, and I'm wondering what optimizations can you do for speed and comfort.  I know F models can be brought up almost to J level but I heard the C wing is a different shape (so that's something you just live with), and J cowling mods don't fit a C...is that true?   Also, for some reason I've never seen a C with recessed armrests... Are the walls by the front seats different from as J so that mod is impossible?  Also, the earlier models had a smaller rudder... Does that mean they have poor spin recovery?

Thanks for any words of wisdom.

[ShuRugal]

None of our Mooneys have great spin recovery, but they all passed the certification requirements of 3 turns or less.... Just expect to use all three turns if you do find yourself in a spin (better to learn what DMMS means and not get near spin threshold)

The J cowl can be fitted to the C, but it's a lot of work (multiple weeks worth according to the IA I bought my C from, he was planning to do that conversion but never got around to it), not a drop in replacement.

The J windscreen can be installed with a parts kit from LASAR, they also have lots of aerodynamic add-ons... About 10-15 AMU worth last time I looked.

Sent from my Pixel 3a using Tapatalk

[0TreeLemur]

Our '67C has recessed arm rests.

If speed is your mission, then you'll start coveting J's as soon as you realize your C will never go as fast as a J even after you put a bunch of money into it for mods.  It has 20 fewer HP.  Those 20 horses add speed that no mod short of an STC'd upgrade to an IO-360 will get you.  That's a lot of money.  Now you have an E with mods.

If you want a J, buy a J.

Optimize a C for speed and you gain a few knots.  Then go fly against 20 knot headwinds.  You won't notice.

[Hank]

1 hour ago, 0TreeLemur said:

Optimize a C for speed and you gain a few knots.  Then go fly against 20 knot headwinds.  You won't notice.

The straight-and-level-cruise speed envelope for my C, with the same power settings (Key Number = 46) and 7500-10K is 68-183 knots over the ground. I'm generally indicating ~145 mph, and when I check, 145-148 KTAS.

Yes, the 68 knot groundspeed was disappointing while indicating 140 mph, 20"/2500 at 10,000 msl, but when my wife pointed at it and said "good thing we aren't in a Cessna, we'd be going backwards," I could still laugh!   That flight, cruising 4:45 at 4000 -- 10,000 into killer headwinds and going high from GSP -- TYS then back down, only used 42 gallons. Not too bad . . . . But it sure was nice to stand up afterwards!

[A64Pilot]

You will be money ahead of you buy a modified aircraft as opposed to modifying one, lots of money ahead.

‘The modification of course do increase resale, but not nearly as much as they cost.

Edited August 7, 2021 by A64Pilot

[carusoam]

Noob,

Great question!

There are Many M20Cs flying around here that have become forever-planes…

When you have a plane for the long haul… it gets lots of modifications…

None of this is economically sensible…. But neither is a giant one step upgrade to an M20R… 

Vist the Lasar site for M20C mods… 

• Cowl
• windshiled
• engine
• wingtips
• Seals
• interior
• paint

You can get pretty close to M20J performance, or even exceed…  but at what cost?

Go Forever-plane!

Best regards,

-a-

[Mooney Dog]

There's always any number of mods you can do to an airplane. It always comes down to two things though. Time and money spent. 

 

If you are going to get a C/D, get it because you enjoy the plane as it is. Otherwise go for a base model plane that does what you want it to do already and you'll come out much cheaper in the end. This is not including avionics. If you try and make a C/D as fast as possible, you're going to spend quite a bit to do it and might as well bought an E or J model. 

[A64Pilot]

Some of us do run our J’s way leaned out and lower power, I often run mine at 22 squared and 7 GPH. that gives me roughly 135 kts true. The same speed as a C-182, but half it’s fuel burn. I enjoy the almost 20 NM per Gl, which by the time you convert to SM and figure in a highway isn’t in a straight line means if I were driving I’m gettin close to 30 MPG, so I actually burn less fuel than our Miata does.

‘It’s a Mooney’s efficiency that I like, in a NM per Gl perspective it actually burns less fuel than my C-140, which is actually a pretty efficient little airplane compared to its contemporaries, but it’s slow and only carries half as much as Mooney

[hammdo]

My C already had the virtually all the speed mods - and I'm glad it did. The cost to add them now (if you could get them all) would be very expensive. Best to find a good plane with good avionics ( or search for a good J with good avionics).

-Don

 

[Prior owner]

I say love the plane for what it is….if you’re feeling slow, then go race a Piper and feel better about your plane. My D/C is faster than my buddy’s fuel injected Piper Arrow.

 A C (or a D/C) is a sporty little plane. Save the thousands upon thousands of dollars you will spend going 4-5 knots faster and use it on hotels and avgas for some really cool, long journeys in your Mooney. Or hold the money back for the unexpected engine overhaul….which happens. Or take the path of ob$e$$ion for $peed- either way, it’ll be rewarding. Just a different way of spending your money.  Also, a good autopilot will get you there a few minutes faster, just like a speed mod.

 

[DXB]

On 8/7/2021 at 10:36 AM, MooneyNoob said:

Hi all,

I'm thinking of getting a C... Really a converted D, and I'm wondering what optimizations can you do for speed and comfort.  I know F models can be brought up almost to J level but I heard the C wing is a different shape (so that's something you just live with), and J cowling mods don't fit a C...is that true?   Also, for some reason I've never seen a C with recessed armrests... Are the walls by the front seats different from as J so that mod is impossible?  Also, the earlier models had a smaller rudder... Does that mean they have poor spin recovery?

Thanks for any words of wisdom.

C wing is the same, F had a slightly different wing in '67 only.  Hard to find a J mod for the cowl; @Sabremech has an ongoing cowl mod project that includes the C. What is this armrest thing you speak of  ?   The pre-'69 Cs and Es have a shorter rudder, but they are not notably deficient in rudder authority during landing - don't spin any Mooney!!

[0TreeLemur]

 

On 8/7/2021 at 3:48 PM, A64Pilot said:

Some of us do run our J’s way leaned out and lower power, I often run mine at 22 squared and 7 GPH. that gives me roughly 135 kts true. The same speed as a C-182, but half it’s fuel burn. I enjoy the almost 20 NM per Gl, which by the time you convert to SM and figure in a highway isn’t in a straight line means if I were driving I’m gettin close to 30 MPG, so I actually burn less fuel than our Miata does.

Since we got our JPI 900 synced up with the GPS in our C, it outputs MPG.  Fun to watch.  I cruise at 24 sq. down low (TAS 140), and WOT 2500 above 5000 ft (TAS 143).  MPG varies from 13 to 20 all depending on the winds.

[Utah20Gflyer]

Here are the speed mods I recommend for a C model.

1.  Strip out all unnecessary weight, remove all inop or unnecessary equipment.

2.  Clean and wax the plane. 

3. Verify correct rigging of all control surfaces.

4. Verify gear doors properly adjusted. 

5. Dynamically balance the prop.

Pretty much anything else is a waste of money.   If you want a plane faster than a C then buy a E or J, K etc. 

 

[steingar]

The absolute best speed mod is adding more fuel.  Not having to stop makes trips lots shorter.  All the other speed mods pale in comparison. Most you won't even notice except on the longest trips.  Not having to do a half hour fuel stop is a biggie.

[hammdo]

While I have many speed mod's already, this would be the only one I'd do (besides the 201 windshield) if  I had to choose. I would probably only use 20 of the 36 gallons (max weight limit with 2 people) but sure would be nice to fly without a stop (just not sure my bladder could wait ;o)...

-Don

 

[Skates97]

Armrests can be "added" if you replace the interior trim panels. This is our 1965 C/D interior, the panel has changed significantly since we purchased it but you can see the armrests in the picture.

[Bolter]

9 hours ago, Utah20Gflyer said:

Here are the speed mods I recommend for a C model.

1.  Strip out all unnecessary weight, remove all inop or unnecessary equipment.

2.  Clean and wax the plane. 

3. Verify correct rigging of all control surfaces.

4. Verify gear doors properly adjusted. 

5. Dynamically balance the prop.

Pretty much anything else is a waste of money.   If you want a plane faster than a C then buy a E or J, K etc. 

 

What are your thoughts on the cowl mouth enclosure and brake flipping?  Relatively low cost speed mods that can be done by any A&P without a lot of time.  

[Hank]

27 minutes ago, Bolter said:

What are your thoughts on the cowl mouth enclosure and brake flipping?  Relatively low cost speed mods that can be done by any A&P without a lot of time.  

The guppy mouth closure is less a speed mod than a cooling improvement for the engine. Seems the huge front opening is too large, and in cruise air actually comes out the front instead of going down between the cylinders and out the cowl flaps. If this has not been done, I'd make it a priority. 

[Utah20Gflyer]

2 hours ago, Bolter said:

What are your thoughts on the cowl mouth enclosure and brake flipping?  Relatively low cost speed mods that can be done by any A&P without a lot of time.  

I'd agree with Hank that the cowl enclosure mod is more of a cooling mod which may be worth it if you have issues keeping your cylinders cool.   Flipping the brakes is unlikely to make much of difference, likely less of a difference than waxing the plane.   The issue is it takes a lot of money and effort to make even a small speed difference and there are already so many little things you will have to do to get your Mooney into excellent condition and set up the way you like it.

  I think the low hanging fruit is doing what you can to make your plane a fast C rather than a slow C.   I'd focus on making sure everything is rigged correct and running smooth. 

Owning a plane is A LOT of work,   a year and a half in I still have a sizable list of little tweaks I want to make the plane just the way I like it.  Currently I'm working on upholstering the glare shield, improving panel lighting and headset cord management.    

In the end it's your plane and your money so you get to choose what is important and as long as you are happy with your choices no one can tell you it was the wrong choice.  

 

 

[steingar]

Someone posted on this here site that the dude who designed that cowl mod did it to make the airplanes look better, and that it has naught to do with speed or engine cooling.

[cliffy]

Buy what you ultimately want and NOT build what you think you want!

You will be big money ahead and not always in the shop

It will cost you  WAY more than you plan and the expected outcome in speed increase will not happen.

Just calculate a few of your normal trips between 135 kts  and 145 kts to see how many minutes you actually SAVE FOR YOUR MONEY

Its been said here many times -  It costs about 1 AMU per knot increase in speed (1 AMU = $1,000 USDs) AND all the mods are NOT 

going to add up to all the expected increases for each one   Its not a linear progression.  

The AMU cost may be higher today!  A lot of money and down time for a small gain

Think about the plan long and hard before you go down that path.

[Guest]

The AMU hasn’t been adjusted for inflation in all the years I’ve been here.  It’s got to be around $1250.00 by now.

[FlyingDude]

On 8/10/2022 at 1:54 PM, steingar said:

The absolute best speed mod is adding more fuel.

I do agree that intermediate stops cost 1hr on average, but when I look at my logs, there are a handful flights exceeding 3.5 hr legs. But I did notice that TAS decreases 5-7kts at MTOW from 300lb payload. So unless I'm going to find dirt cheap fuel (i.e. slightly less outrageous than the rest) along my path, I opt for fueling at my destination and carrying enough+1.5 hr reserve...

[FlyingDude]

On 8/10/2022 at 1:18 PM, Utah20Gflyer said:

Here are the speed mods I recommend for a C model.

1.  Strip out all unnecessary weight, remove all inop or unnecessary equipment.

2.  Clean and wax the plane. 

3. Verify correct rigging of all control surfaces.

4. Verify gear doors properly adjusted. 

5. Dynamically balance the prop.

Pretty much anything else is a waste of money.   If you want a plane faster than a C then buy a E or J, K etc. 

 

Agreed. I'd adapt this last to my "progress" of gaining 8kt as:

1. Rig the plane well. 

2. Check that the ball in TC is perfectly aligned (panels can sag). Then Rig it better until it flys straight and level hands off with the ball centered. 

3. Remove unused wires. I found 15+ lb of wires, clamps and relays leading nowhere. Prev mechanics just removed old avionics and left their wires hanging. Yes I weighed the lot. I'm keeping them in my stash.

4. Clean the gunk off. It really weighs and adds drag on the underbelly (rough surface).

5. I honestly didn't notice any difference in waxing the plane over just keeping it clean. YMMV.

6. Prop balancing increased our comfort A LOT but with no noticeable difference in speed.

I already paid for the brake caliper forward swap STC. I might do it in the future. I'm not counting on any increase in speed but quicker access to the brake caliper bolts and easier safetying will shorten service time ...

But like the others said, I have an E and it'll always be an E. If I won the lottery, I'd go with Piper Malibu, not modify my E... The 10kt difference here and there between different pre-J Mooney models amount to 15 min in a 600nm leg. I'm sure you've wasted more time than that taxiing on a busy airport...

[EricJ]

On 8/10/2022 at 10:54 AM, steingar said:

The absolute best speed mod is adding more fuel.  Not having to stop makes trips lots shorter.  All the other speed mods pale in comparison. Most you won't even notice except on the longest trips.  Not having to do a half hour fuel stop is a biggie.

The personal bladder stretch mod is the tough one.    Jose should have included his relief tube mod as part of the extended tank STC.