High altitude performance, M20J

[Hondo]

Greg1

 

Check out the M20J POH.  http://www.deltaaviationllc.com/Nav%20Page/POH/M20J%20POH3203B.pdf

 

I have the older style POH which uses tables for takeoff performance.  At 8000' with an OAT> 20C, it just shows dashed lines.

The DA at your field can easily exceed 10000.  The J can only produce 70% power at a 10000 DA.

At 20C, gross weight, no wind and pressure altitude of 8000, the POH shows 5077 to clear a 50 foot obstacle with a climb at 71KIAS.

 

If you are used to turbo performance, it will seem marginal, but taking off well below gross on cool/cold days is probably safe.

 

Since you could afford to maintain a Cessna turbo, you might be surprised how much less it costs to maintain a Mooney turbo.  Why not check it out?

[M016576]

Thanks for all the great input. To be a little more specific about my situation, I am looking for an airplane to replace my Cessna P210. As I approach retirement, I'm not going to be able to support the care and feeding of this aircraft. I do enjoy the turbo power, the useful load, the pressurization, and the known ice capability. I don't enjoy the fuel burn, maintenance upkeep on all those systems, and insurance cost. I want to go into an M20J with my eyes wide open. I don't plan to takeoff at noon in the summer at max gross.. What I would like to do is takeoff at 8AM at 200 pounds under gross and climb to 12500 MSL with reasonable authority. Any more thoughts along those lines?

The J is perfect for that mission. You'll get p210 speeds on 9 gph fuel burn.

Source: J ownership for 4 years traveling between KIYK-KSUN about 6-10 times a year. Most trips between 10-12K.

[jlunseth]

Ever noticed that the high altitude airports are generally longer?  KANK, for example, is over 7,000.  Leadville is 6400.  Where our Midwestern "short strips" are 2800-3500, theirs are 5500 and up.  In a turbo all you need to do is what you should already be doing, manage your airspeed and let the plane decide when it is ready to fly, or to quit flying.  The trick is not to get excited because you are at LXV and do something different, like forcing the plane down because you are using more runway than you are used to.  It can be a little more exciting in an NA though.

[M016576]

Ever noticed that the high altitude airports are generally longer? KANK, for example, is over 7,000. Leadville is 6400. Where our Midwestern "short strips" are 2800-3500, theirs are 5500 and up. In a turbo all you need to do is what you should already be doing, manage your airspeed and let the plane decide when it is ready to fly, or to quit flying. The trick is not to get excited because you are at LXV and do something different, like forcing the plane down because you are using more runway than you are used to. It can be a little more exciting in an NA though.

Much of it is just a matter of instruction and experience. You're right, though- the first time a flat-lander finds a high alt airfield, the speed has a tendency to surprise them.

[FoxMike]

Greg

I have lived in Co. for 40 years or so.  Most of the time I have  owned a turboed airplane.  When I have occasion to fly a NA airplane it only takes a little while to want to get back to a turbo.  If you are used to operating a turbo it will not take long to miss it.  I am in an out of ANK a half a dozen times a year.  You could certainly could operate a 201 from there safely but you will probably need to change some of your flying habits.  I think that owning a 231 would be a better choice but I well understand the desire for lower operating cost.  I would venture a guess that your operating cost would drop considerably if you decided to operate unpressurized turbo of any stripe.  Pressurized pistons airplanes were a challenge to properly design (nobody got it right)  thus the excessive cost.  I own a Bravo and am happy with the performance.  Good Luck.

[glenv6]

This is the thread I was looking for...  Not to hijack the topic, but I recently acquired an '82 M20J and was wondering about the usable service ceiling of the airplane.  I transitioned from an old C35 Bonanza that ran out of steam around 10-11K feet.  I recently completed a round trip between Dallas and Santa Monica in the new-to-me Mooney flown at 11K feet and was really very impressed with the perfomance of the airplane.  With only me onboard, bags and full fuel (93 gal) I climbed to 11K feet with no cooling issues and I still seemed to be able to achieve a solid 500ft/min or better climb rate in the Mooney.  I'm not bashing the old C-model Bonanza - I loved that airplane, but on similar trips it struggled to climb without cooking the cylinders and could really only manage about 200ft/min in climb once I got above, oh, 10K feet.

 

It is comforting to know that you guys are flying these things in the 13-16K feet altitude range without thinking twice about it.  Those altitudes would keep me out of the bumps across the Southern Rockies.  An O2 bottle is in my immediate future!

 

Regards,

Glen

[KSMooniac]

Glen, you'll find you can make it up to 17k in the summer, especially with a light load, if you're patient.  If you're running to CA and back regularly you'll appreciate the O2 and higher altitude, especially heading east.  The only caveat is if you're IFR & IMC at those altitudes, you won't have many good options if you run into ice in the clouds since you cannot usually top them.

[aaronk25]

I routinely fly at 15-19k in my J, if the winds are favorable. I'm installing a power flow exhaust that I'll test and give a write up on in about a month.

Powerflow says 7kts and 2000ft additional ceiling.....we will see!

[carusoam]

Welcome aboard Glen.

Bashing another guy's plane is not usually proper ...

But here, you will only partially offend two people that fly the B made plane.

That's less than a 1% offense ratio...

Now, if you were to tell somebody you prefer to fly your new2U Mooney at 50dF ROP... The offense ratio increases significantly...

Best regards,

-a-

[glenv6]

Good point, Scott - I have picked up ice in IMC in the Bonanza and the airplane did quite well getting out of it.  What's the Mooney like with some ice on the leading edges?

[glenv6]

Wow, can't wait to read about the Powerflow!  The OP of this thread may also be interested in this one...

[glenv6]

Thanks Carusoam!  I am with you, man...  LOP vs anything else discussions generally belong in the Politics and Religion section!     

[WardHolbrook]

This scenario is one of the prime reasons why they hang turbochargers on airplane engines. Remember that an aircraft's ability to climb is a function of excess horsepower above that which is required for level flight. When you start limiting weight all you're doing is reducing the amount of horsepower you need to maintain level flight at any given airspeed. With a NA powerplant you loose power at the rate of about 2% to 2.5% per 1000 ft of DENSITY altitude. Climb performance is all about one thing - available power. I'm not sure of the "real" numbers, but let's talk hypothetically - let's say that our hypothetical Mooney requires 100 hp to maintain level flight at cruise flight. If you've got a 180 hp Lyc in the nose you've got 80 "excess" hp to climb with at SL, but at 10,000 feet DA you're down to roughly 35 excess hp. Now let's say you've got a 200 hp E model. That 20 extra hp isn't going to do much when it comes to increasing your cruise speed. (To double your cruise speed you've got to quadruple your hp - every thing else remaining the same.) However it will make a difference in your ability to climb - now instead of just 80 excess hp at SL, you've got 100 and at 10,000 ft instead of 35 you've 50 hp to play with. Turbocharging essentially allows you to develop full-rated power up to its critical "density" altitude. Now instead of having 50 excess hp to play with, your turbocharged (or turbonormalized) 200 hp Mooney will have a full 100 excess up to climb (and cruise with) up to it's critical altitude. Based upon the principle of there's no such thing as a free lunch, there are penalties associated with a turbo - they generate more heat (more power = more heat) and they're not as efficient at lower altitudes. So if you don't spend much time above 10,000 ft (density) altitude they don't make much sense. As far as maintenance costs go, I've flown a few thousand hours behind turbocharged piston engines and they're not that big of a deal to live with. Any additional maintenance costs are easily dealt with by adjusting the hourly budget just a little. The numbers will be different when you start comparing other models, but the principles and concepts remain the same when you compare a J with its turbocharged direct counterpart the Mooney 231. You can add intercoolers to deal with the excess heat and Merlyn wastegates to increase the critical altitude on a 231 (or you can buy a 252). Bottom line is this, with all aspects of aircraft takeoff/climb/cruise performance, it's all about horsepower. More is better and never, ever in the history of general aviation has anyone ever said "I've got too much power". That's also why Powerflow exhausts help a bit - every little bit helps.

[KSMooniac]

Good point, Scott - I have picked up ice in IMC in the Bonanza and the airplane did quite well getting out of it.  What's the Mooney like with some ice on the leading edges?

 

I don't have much icing experience because I'm scared to death of it, but generally Mooneys are far less tolerant of ice than most other airplanes.  The laminar flow wing gives us efficient speed, but as soon as you get some ice on it you'll lose speed quickly.  if you're up very high and at a lower IAS, your safety margin starts to shrink quickly.  If you're up high in a non-turbo Mooney and start picking up ice, you won't be able to climb out of it, so your options are descend to warmer air (if available, and you're above the MEA) or turn around and go somewhere else.  When I found ice in late May over Utah at 15,500', I ended up turning around and spending two unplanned nights in Moab.    

 

TKS and a turbocharger give you a lot more options, but even if I had those I'd still be awfully scared of it in a Mooney.

[carusoam]

Excess cash? Go with the FIKI TN IO550...

And fly often...

Not the once a month kind of often.

So... Will the new Acclaim have the TN 310hp???

Best regards,

-a-

[aaronk25]

It will be interesting to see how much the powerflow will help but after looking at my factory muffler it's obvious that the exhaust from one cylinder adds pressure in the muffler that lasts for some duration of time and makes it harder for the next cylinder firing to evacuate the exhaust. Which is why high performance engines wether it be cars, motorcycles ect design exhaust systems that don't create additional back pressure on other firing cylinders.

My guess is it will make a little difference. I needed a muffler and shroud anyway.....

I wish I could add the electro air ignition system to my plane as my guess is with 35-37 degrees of timing up at 13k-15k I'd run closer to 165-167kts, instead of 156k.

Altitude starts working against our simple engines as high altitude high power operations need max rpms and more timing....something we currently don't have.

I got dual mags on a single shaft which isn't stc'd but maybe I could get a field approval.

[Greg1]

Sorry I've been away from this thread for so long.  Anyway, again, thanks for all the great input.  Ive read all the recommendations and done some research.  Just about the time I've convinced myself that the K model is the way to go, I reread this article http://www.mooneypilots.com/mapalog/M20K231%20Eval%20Files/M20K231_Eval.htm.  When I get to the part that begins with "But there's never a free lunch", I pause and start the whole turbo vs non-turbo debate in my mind again.  My typical trip involves taking off from KANK in the morning with 2 people on board and full fuel.  I then fly about 600 NM easbound to KFYV.  There is some terrain going easbound, but 11,500 MSL will clear it all.  On the return flight I'm usually closer to max gross weight for takeoff, but will have burned off a lot of fuel before arriving back at KANK in the afternoon.  So I think the J will fill the bill for that kind of flight.  KANK is situated just east of Monarch Pass which lies on the continental divide.  So obviously, I'm not going to be able to take off from my home airport and proceed westbound without a lot of climbing first.  But that's been true for the P210 also.

My feeling as I of right now is that I'll probably end up going with a J.  But I could wake up tomorow and not be able to get the K out of my mind.

Any thoughts on the above article's implication that the K's engine will require at least one top overhaul and two turbo overhauls to make it to TBO?

[AndyFromCB]

I don't have much icing experience because I'm scared to death of it, but generally Mooneys are far less tolerant of ice than most other airplanes.  The laminar flow wing gives us efficient speed, but as soon as you get some ice on it you'll lose speed quickly.  if you're up very high and at a lower IAS, your safety margin starts to shrink quickly.  If you're up high in a non-turbo Mooney and start picking up ice, you won't be able to climb out of it, so your options are descend to warmer air (if available, and you're above the MEA) or turn around and go somewhere else.  When I found ice in late May over Utah at 15,500', I ended up turning around and spending two unplanned nights in Moab.  

 

TKS and a turbocharger give you a lot more options, but even if I had those I'd still be awfully scared of it in a Mooney.

 

From my experience, TKS makes you pretty much impervious to light to moderate ice as long as fluid is flowing. You have about an hour to decide what to do and quite frankly I've never seen icing last more than 15 minutes, even crossing fronts, as long as done with some brains, as in at 90 degrees and not along the front. Nothing and I mean nothing sticks to the airframe. It's almost kind of "fun" watching it grow on your landing lights.

 

Mooney's TKS installation is one of the best. The trick is to have the system recently primed because otherwise it's a long 5 to 10 minutes to shed anything on max setting.

 

As to ice without TKS, I've landed with about an inch on my Bravo last spring in Wyoming because I didn't expect it and doing it flap-less at 95knots over the fence didn't pose any major problems. It did touch down at about 65knots instead of the usual 55knots so it does bump up your stall speed quite a bit and it did require carrying about 20inches of manifold pressure to keep the speed up so I'd be worried about doing it in a naturally aspirated bird.

[KSMooniac]

I agree with Jim... we know a LOT more today about engine management and have far better instrumentation to successfully manage an engine to help it make a full TBO run without a top overhaul.  Caveat... it depends on how well the engine (and especially the cylinders) are assembled originally!  

[231LV]

I fly a K and have been flying it now for 10 years...prior to that I flew a C model. I understand the difference between the C and the J and a J is a sweet plane compared to the C. The K outmuscles the J in every way....run LOP as standard operating protocol and get a good engine monitor and your engine will easily make TBO and beyond. Even with a tired GB engine, my major expenses have been around avionics and secondary systems like exhaust and fuel which simply wear out after 35 years of use. The top overhauls were caused by a single probe monitor and running 50 ROP which got CHT's up to 430 degrees and cooked the jugs....keep all jugs at 380 and below and your engine will run great! The K is the most efficient plane out there where 175 KTAS on 10 gph is a reality.

[Bennett]

I've had a K (231 converted to a 261) for about 16 years, and a J for about the last 3. Both are great aircraft, but for truly high altitude flying I would recommend a K, preferably a 252 or any of the 261/262/263 conversions. Just be sure you have an all cylinder engine monitor, and use it to keep temperatures in a reasonable range. Of course a Rocket conversion offers higher speed.