This is why I upgraded from a "J' to a "K"

[FAST FLIGHT OPTIONS LLC]

...I offer the following pictures as proof of the awsome performance of the older turbo Mooneys. 

205KTS @ 13K on 10 GPH.  I made it from Memphis, TN to Jacksonville, FL in just over 3 hours and it cost me about 100 bucks in fuel. Tons more leg room then in coach and the snacks were free   Delta doesn't even come close to touching that!

 

[kortopates]

No fair bragging about ground speeds - its TAS that matters!

But if you really want to see what that K can do, you really need to get up another mile or more higher and really take advantage of the increased TAS you'll get at about 2 kts/1000' and the typically stronger westerly winds when headed west like that.

Enjoy!

[scottfromiowa]

....or East.

[FAST FLIGHT OPTIONS LLC]

Quote: kortopates

No fair bragging about ground speeds - its TAS that matters!

But if you really want to see what that K can do, you really need to get up another mile or more higher and really take advantage of the increased TAS you'll get at about 2 kts/1000' and the typically stronger westerly winds when headed west like that.

Enjoy!

[kortopates]

Couldn't agree more about preferring the turbo.

You shouldn't see much of an issue with the summer heat, but when it is real hot, just be sure to climb a bit faster than Vy as you climb up to cooler air. Also, don't throttle back ot cruise climb - you should see your engine will climb coolest at full power because its set to run richer at full power. Throttle back and you'll see temps go up significantly. In cruise, temps actually are harder to keep cool up higher because of the thinner air, but don't hestitate to open cowl flaps when you need too. When I flew a 231 before my 252, I hated to open them because of the speed penalty but engine longevity really prefers CHTs below 390-400 so use them as needed. Many 231 owners get their cowl flaps adjusted so that they open more in the "in-trail position" so that they don't have to fully open cruise. In the 252, I can micro adjust electrically with essentially no speed loss. But if you normally cruise at about 65% power (10GPH) you should be fine temperature wise. I've had no problem taking off with DA's well above 11K at max gross wt. The K just takes longer to accelerate to Vy than your 201 did, but once there you'll get the same climb rate to your critical altitude (about 17K in your 231 and 23K in my 252). 

[jlunseth]

I second everything he said except the crit. alt.  I have the Merlyn and Turboplus Intercooler and have been as high as FL220 with throttle left, so I can't say I have found my plane's critical altitude yet.  Because of the intercooler I consider my redline to be about 36-37 rather than 40.

As great as a trip like that is, we have to admit there will also be days where it just works out better because of adverse winds up high, to stay down low.

The top GS I have seen so far is 242 KPH.  Descent from those altitudes can be a real yeehaw.  Coming in from Bismarck I have had to start my let down a hundred nm out, though 75 is more normal.  Don't want to hurt anyone's ears.

Now, I hate to tempt anyone, but I am told by someone who knows that speedbrakes are a must on the slick Acclaims and some Bravos.  Tip the nose down just a little to descend and you will go over Vne without em. 

 

[Earl]

I must have been flying from Orlando to Atlanta the same day.  On my northerly treck my GS was around 150 kts at 65% HP and 11.5 gph at 10,000'.  My crab angle was 35 degrees.  When I turned to the west to RYY my ground speed dropped to 116 kts.  Heck of a head wind even at lower altitudes.  I have an 86 252.

[Hank]

You're all making me feel better about my trip home from the beach at the end of July, when my groundspeed was 104 knots at 10,000 msl. Yes, I fly a  mighty carberueted C-model!

[rbridges]

Quote: ehscott

I must have been flying from Orlando to Atlanta the same day.  On my northerly treck my GS was around 150 kts at 65% HP and 11.5 gph at 10,000'.  My crab angle was 35 degrees.  When I turned to the west to RYY my ground speed dropped to 116 kts.  Heck of a head wind even at lower altitudes.  I have an 86 252.

[FAST FLIGHT OPTIONS LLC]

Quote: jlunseth

I second everything he said except the crit. alt.  I have the Merlyn and Turboplus Intercooler and have been as high as FL220 with throttle left, so I can't say I have found my plane's critical altitude yet.  Because of the intercooler I consider my redline to be about 36-37 rather than 40.

As great as a trip like that is, we have to admit there will also be days where it just works out better because of adverse winds up high, to stay down low.

The top GS I have seen so far is 242 KPH.  Descent from those altitudes can be a real yeehaw.  Coming in from Bismarck I have had to start my let down a hundred nm out, though 75 is more normal.  Don't want to hurt anyone's ears.

Now, I hate to tempt anyone, but I am told by someone who knows that speedbrakes are a must on the slick Acclaims and some Bravos.  Tip the nose down just a little to descend and you will go over Vne without em. 

 

[jlunseth]

Having flown a 231 for awhile, the issue with the aircraft is that the engine is minimally designed.  Probably it was designed as well as they knew how to design one at the time, but it had a reputation for being tempermental and burning cylinders.  It also had a reputation for being difficult to keep cool at the higher altitudes.  I have the LB engine, Merlyn and intercooler.  The later turbo Mooneys were even more robust in the cooling department, with dual turbos and intercoolers, and a better induction design. 

Even with my "improved" engine I can see some of the issues with the old one.  For example, the redline for the Compressor Discharge Temperature (CDT) is 280dF.  The purpose of this redline is to prevent overly hot air from entering the induction system and causing detonation in the cylinders.  I have taken my plane up to the lower FL's, and at about FL200 I started to see a constant rise in CDT which I could not control by the usual means (cowl flaps, richer mixture, etc.).  The primary reason is that the air is so thin up there that the engine does not do a very good job of cooling, even though the OAT is maybe -10C or colder.  The addition of the intercooler helps quite a bit here.  So while I had CDT's in the 295 dF range, the Induction Air Temp. (air going in to the cylinders) was more than 100 dF cooler.  With the old GB non-intercooled engine, I would have been over CDT redline and in big trouble.  However, the CDT redline does not count with the intercooler, the IAT is what counts, and that was cool and safe.  The redline that counts for protecting the turbo is actually the TIT, and that was not materially affected by the higher altitudes.

The intercooler generally helps keep the engine running generally cooler, even at low altitudes, by cooling the induction air.  It probably helps with the crit. alt. a little, but that is not so important to me.  What is important is keeping the engine cool.

There is also a tendency for the part of the cylinders run on the hot side, particularly 1 & 2, which are the two rearmost cylinders.  The intercooler cannot stop them from running hotter than the other cylinders, but it does help by keeping all the cylinders cooler. 

Bottom line, I just do not see the heating problem in the Flight Levels or elsewhere that the nonintercooled GB was prone to produce.

The Merlyn is a big help also.  Here again, I have not flown the 231 engine without a Merlyn, but what I read about it is that managing the throttle on takeoff is a task that takes some practice.  Not so with the Merlyn.  My typical approach is to put in about 60% throttle on takeoff and let the turbo kick in.  Once it does, I ease it in to about 36-37" and it will stay there without any work on my part. 

The other thing the Merlyn does is change your critical altitude, i.e. the altitude at which, at full throttle, the engine is no longer producing 100% HP.  This inhibits your climb rate, and as I understand it the climb rate to the FL's over 200 got quite slow.  The reason for this is that the standard engine has a fixed wastegate.  So once you reach full throttle, the wastegate is still open, allowing exhaust gases to escape that could be used to power the turbo.  The Merlyn wastegate self adjusts, so it varies how much exhaust is vented before the turbo.  This helps the turbo to run a lower speeds where full turbo is not needed, and also means that the wastegate will fully close as altitude increases, allowing you to climb to higher altitudes at full power. 

I would say both are very good additions to a 231.   

[231Pilot]

Thanks for the very thorough explanation jlunseth.  I, like other 201 owners on this board, frequently debate making the switch to a turbo as my flight mission requirements change.  How long did you have to receive additional instruction to develop some measure of proficiency in flying a turbo?  How long before you felt confident in your management of engine temperatures?

If a K model does not have built in oxygen, do you feel that is a deal breaker?  Or do you recommend having a portable oxygen system on board as a backup to the built in?  Is it economically feasible to retrofit a built-in oxygen system to a K?

Just wanted opinions from the well informed.  Thanks.

[FAST FLIGHT OPTIONS LLC]

Quote: 201Pilot

Thanks for the very thorough explanation jlunseth.  I, like other 201 owners on this board, frequently debate making the switch to a turbo as my flight mission requirements change.  How long did you have to receive additional instruction to develop some measure of proficiency in flying a turbo?  How long before you felt confident in your management of engine temperatures?

If a K model does not have built in oxygen, do you feel that is a deal breaker?  Or do you recommend having a portable oxygen system on board as a backup to the built in?  Is it economically feasible to retrofit a built-in oxygen system to a K?

Just wanted opinions from the well informed.  Thanks.

[231Pilot]

Thanks.  So are you going to leave your user name as 201-FLYER, or are you going to upgrade it too?

[FlyDave]

I have an article from Mooney Pilot (2001) that David Trinidad wrote on turbo vs. non-turbo. If anyone wants it PM me and I'll email it to you.

[RJBrown]

Quote: 201Pilot

If a K model does not have built in oxygen, do you feel that is a deal breaker?  Or do you recommend having a portable oxygen system on board as a backup to the built in?  Is it economically feasible to retrofit a built-in oxygen system to a K?

 

 Only the 1979 K models came from the factory without oxygen. It was standard equipment from 1980 on. Some 79s have had it added. Some are OE like and some are not. If you are interested in a 79 find out what it has for O2. When I had my 1980 K I had BOTH on board and portable systems. There will be times when there is no way to refill and you will need the backup. When flying solo in the 20s I always had the backup sitting on the RF seat set up and ready to go.

Even now in my J I ALWAYS carry oxygen.

I miss the turbo more than I expected. If I find a reasonable way to upgrade I will.  

[KSMooniac]

Regarding engine management, the absolute best education you can get is thru the Advanced Pilot Seminar.  (www.advancedpilot.com)  One of the gems I learned there is that the "let the turbo cool down for a few minutes before shutting down" idea is a total myth.  They show you the data that proves the turbo is at it's lowest temp right at touchdown, and every second after touchdown it gets warmer.  

[jlunseth]

Quote: 201Pilot

Thanks for the very thorough explanation jlunseth.  I, like other 201 owners on this board, frequently debate making the switch to a turbo as my flight mission requirements change.  How long did you have to receive additional instruction to develop some measure of proficiency in flying a turbo?  How long before you felt confident in your management of engine temperatures?

If a K model does not have built in oxygen, do you feel that is a deal breaker?  Or do you recommend having a portable oxygen system on board as a backup to the built in?  Is it economically feasible to retrofit a built-in oxygen system to a K?

 

I don't know that I am the "well informed,"  I just fly one.

My answer on the training would be the same as 201's, the insurance carrier required a few hours of training in type M20 (not necessarily K).  I read up and started flying.  I did learn somethings as I went though.  Uh.  Well.  Alot of things about flying in general and about turbos.  On the turbo aspect, I found that generally I am in "rare air," meaning that there are not alot of instructors who can teach how to fly a turbo in reality.  All instructors know the principles, but training is aimed at FAA type things, and you won't find alot of questions on turbos on the FAA test.  For starters, I read the manual and all the articles on the MAPA site.  What reallly helped was to read John Deakin's articles on Pelican Perch, that's avweb.com

I also went to the GAMI Advanced Pilot Seminar.  It was very good, but I was a little disappointed that it focused primarily on normally aspirated.  From a mixture standpoint (and that's what APS focuses on), normally aspirated is actually more complicated to operate than a turbo.  In my turbo, you fly to altitude at full rich and WOT (no leaning during the climb), lean out as desired at altitude, then leave the knobs there for landing. In the turbos, APS also spends most of its time on the big bore turbos, and not so much on the "small bore" TSIO-360 that is in the K. The small bore TSIO360 is more finicky about operating parameters than the big bore turbos. Lots of good general principles though.

Mostly you learn from experience.  And you also learn by watching the gauges and playing with the knobs, while listening to the Sat radio and cruising 190 kts. GS for a few hundred miles, up in the high still air where there is not much else to do except watch gauges, twiddle with knobs, and figure out how to get your bladder to do 4 hours straight.  Its spectacular up there.

We need to have a club or something, so we can help train each other.

[fantom]

Quote: KSMooniac

One of the gems I learned there is that the "let the turbo cool down for a few minutes before shutting down" idea is a total myth.  

[jlunseth]

In my post of earlier this morning I said that I go to altitude and then "lean out as desired."  I was asked does that mean that I stay at WOT and lean the engine, and no, I don't.  I let the plane speed up to cruise, close the cowl flaps (which gets me the last ten knots to cruise), then set the prop to 2450 - 2500 and set the MP a little higher than desired.  I have found that the MP number varies depending on temp. and altitude.  Day before yesterday at 17k, I was getting about 75% HP at 26.7 MP and 2450 RPM.  I was leaned out to 13.7 gph at 125 ROP. 

I don't think the K engine would be happy very long running at WOT.  I understand some people have been running the Acclaim that way (WOT and LOP), and there have been some cylinder problems.  But that's a different engine.  Bigger bore.  The K engine is more finicky.

The JPI 930 has an HP algorithm that seems to be pretty good.  It appears to take Induction Air Temp into consideration (the air entering the induction system is denser if it is cooler), and calculates and HP% that is affected by that.  I say that because the calculated % HP appears to change slightly enroute, if the temp goes up or down a few degrees.

[Skywarrior]

Quote: KSMooniac

Regarding engine management, the absolute best education you can get is thru the Advanced Pilot Seminar.  (www.advancedpilot.com)  One of the gems I learned there is that the "let the turbo cool down for a few minutes before shutting down" idea is a total myth.  They show you the data that proves the turbo is at it's lowest temp right at touchdown, and every second after touchdown it gets warmer.  

[Hank]

I don't have a horse in the turbo cooling race, but isn't TIT [Turbine Inlet Temperature] the engine exhaust? What Scott was alluding to is the actual temperature INSIDE the turbo, not at its inlet. Either way, I'm enjoying the simple life, just me and my carberuetor.

[KSMooniac]

Quote: Skywarrior

I guess my JPI 700 is on the fritz, then. I watch the TIT steadily drop after landing for several minutes, then I shut 'er down when it stabilizes.

 

Chuck M.

'91 TLS Bravo

[fantom]

Quote: KSMooniac

[Jsavage3]

I love my J, but I'll admit, I have found myself ogling the 252/Encore.  So, picture yourself a salesman and convince this happy J driver why a 252 or an Encore would be it for me.

 

In addition, consider things like oxygen wear (how 'happy' will my wife be using O2), cost to refill O2 bottles, payload, etc...

 

A casual observation on my part...my J does 160ktas on 10gph at 10,000 feet and I've read a 252 will do 190ktas on 13gph, but only up high (high teens to low FLs) & on O2...roughly the same fuel burn for any given trip.  If winds drive one low, what's the 252 going to do (ktas & gph) at 10,000 feet?

 

I flew in the military wearing helmet & mask for 1500 hrs, so I've had my fair share of O2 use...I'm just not yet convinced that the cost/hassle/pain of O2 use is worth the reward of an altitude engine.  So, here's your chance to convince me that trading my lovely J in for a 252 is meant to be...