The Bravo: One Capable Airplane

[gjkirsch]

I am planning to fly to DTW tomorrow, I will write down the power setting, fuel flow, temps and TAS

[johnggreen]

Scott,

I have experimented with LOP and can get the Bravo to run smoothly, but---------

The but is that I lose a lot of power and speed, more I think than should be a reasonable trade off.  I did my lean peak test relatively low power settings, 2400/27",  so as to not run my TIT's too high.  My peaks spread was 14.6 on first to lean and 14.1 on the last.  The guys at APS said that was close enough, but I think not.

So, at this point, I'm just going to keep on doing what has worked so well for me to date.  I lean to 1650, which the Lyc Operator's Manual and POH say is best power though like another poster said, at low power, peak will come before 1650.

I may adjust my GAMI's once more, to tighten up the low and high cylinders a bit and try again.

But you know, 175-180 knots at 14 gph is nothing to cry about.  The saving of fuel from that point is really irrelevant to me, I just want to preserve my engine.  Like I said in a previous post, my compressions are absolutely like a fresh engine, so I must be doing something right. 

Jgreen

 

[KSMooniac]

I suspect you're right about a 0.5 GPH GAMI spread... that is likely just on the edge of acceptable and you might not be able to run much LOP...maybe 10-20 dF.  Your existing settings and performance sound great, and better than other M20M's apparently, but I suspect they *could* be better.  Since you have the turbo, you *should* be able to to make up all of that lost speed by increasing MP (just like the APS guys preach) so that there is no trade off like I have with a NA M20J.  

I'm not a Bravo owner or operator, but am always curious about any Mooney which is why I'm interested.

One thing I'd like to hear from you on a slightly related note, now that you have taken the APS Class (I assume you did the on-line one only, correct?) what do you think of Lycoming's guidance related to LOP ops, and engine management in general?  

[johnggreen]

Scott,

Yes, I took the online course.  I would like to go to the seminar and may.  I think there is a lot of understanding that would come from the questions and answers that you would be able to listen in on.

As to Lycoming's guidance; I thought APS gave some excellent "observations".  Their conservative approach was indeed likely driven by marketing and the fact that the injectors were not that closely balanced from the factory.  I am assuming, of course, that you have heard all the APS explanations.

As for the Lyc Operator's Manual, I think that if you study it closely, you will get a good understanding of your engine and it's capabilities ROP.  There is no doubt that running LOP requires a good understanding of the operation and handling of your engine and there is also no doubt that I've seen a lot of pilots who could afford an airplane that simply wouldn't have the "skills" to manage an engine LOP.  To be fair to the engine manufacturers, they took the course of reasonable least resistance based upon the cross section of their engine users.

Jgreen

[KSMooniac]

The live seminar was the best money/time I've spent as an owner, and I'm thankful I went just a few months after buying my plane.  I learned more there in 2.5 days than in many semester-long engineering courses, and I encourage every pilot to go.  The Q&A sessions and seeing the test stand in operation are easily worth the effort and expense.  I think they discount the price too if you already took the online course.

I agree that marketing and factory "deficiencies" over many decades have led to the common practices and APS is doing great work to shine the light on the problems.  

I disagree that running LOP requires any more of an understanding than ROP, and in fact the potential for badness is higher while on the ROP side of the curve unless running very ROP (like 150+ dF ROP).  Most pilots are just taught a recipe with little to no understanding of what really happens with the red knob of death, and I bet any novice pilot could be taught LOP just as easily as leaning to ROP settings.  

[johnggreen]

Scott,

The points I remember are that the marketing boys were always touting speed which means "best power" and the customer service department didn't want to deal with complaints about rough running engines.

Over the years, I've seen many a pilot who would go out and buy, for cash, a new airplane who would literally be challenged by "mixture in" to crank and "mixture off" to stop.

I watched a 200 hour student pilot (he soloed at 80 hours) flying a brand new Skylane (that he bought for cash) fly it straight into the runway one bright Saturday morning in 1982.  Ripped off the nose gear, bent the prop backwards, buckled the fuselage and when I got to the airplane asked me if there was a mechanic on the field to fix the airplane because he needed to fly to Memphis that afternoon.  Swear to god.  I wish that was the only story like that I can recall.

No, I think the manufacturer might have made a good marketing decision with KISS.

Jgreen

[jetdriven]

Quite funny, but true.  I knew a commercial pilot for a freight outfit I worked at, I was getting a ride to San Antonio in a 402. After 20 minutes of the props out of sync "wah-wah-wah", I reached up and tweaked the right prop back a smidge. Engines in perfect sync.  His reply?  "what was that?"

[thinwing]

Funny Byron...you should have said "I can fix the wah wah"and than reach over and pull one of the red knobs!!!KPC

[jlunseth]

I took the APS live seminar in Ada about 18 months ago.  It is interesting to see the "test stand," which I put in quotes because it is a monster big thing.  And of course to see an engine run on it, and see the engine parameters such as cylinder pressure, change as mixture and octane rating are changed. 

The one disappointment was that most of the "how to" part of the class - the part about how to run your engine as opposed to the engine theory part - was keyed towards normally aspirated engines, with some time spent on large bore turbo's.  The Bravo would probably fit into that category, but my TSIO-360-LB does not, and is a different animal to run. 

My takeaway from that class is that a turbo needs to be run 60LOP or more, or 125 ROP or more.  60 LOP is just too much in my engine.  A Piper Warrior is faster.

[fantom]

Quote: jlunseth

The one disappointment was that most of the "how to" part of the class - the part about how to run your engine as opposed to the engine theory part - was keyed towards normally aspirated engines....

[jlunseth]

They spent quite a bit of time on Beech engines, and on turbonormalized rather than straight turbocharged.  From what I recall of the discussion of normally aspirated engines, it was applicable to any NA.  Turbo is just a different animal with the pressurized induction system.  Although I could see how an untuned induction manifold could cause problems even in an NA.

[KSMooniac]

Quote: jlunseth

My takeaway from that class is that a turbo needs to be run 60LOP or more, or 125 ROP or more.  60 LOP is just too much in my engine.  A Piper Warrior is faster.

[fantom]

Rumor has it that a MooneySpace member is trying to resurect the Turbo Normalizer for the IO-360....

Wouldn't that be wonderful....Bill Sandman's product that has fallen on hard times since he passed away:

http://www.m-20turbos.com/content/products/turbo_why.php?link=turbo&cat=why

[FBCK]

In have the same issue with my 1981 231, as I lean it to LOP the speed drops off quickly, as does the MP, if you push the MP back up,  the fuel flow goes back up, so you lean again, speed drops off and so on. I maybe running it a little to lean, but its still running smoothly, I've never done the math between fuel flow and the speed drop off.

[Parker_Woodruff]

Quote: FBCK

In have the same issue with my 1981 231, as I lean it to LOP the speed drops off quickly, as does the MP, if you push the MP back up,  the fuel flow goes back up, so you lean again, speed drops off and so on. I maybe running it a little to lean, but its still running smoothly, I've never done the math between fuel flow and the speed drop off.

[jetdriven]

I tried a LOP climb in the 201 and it will do it, but the climb rate is so bad (<500 FPM,  105 KIAS, 10.0 GPH) that I dont think it saves a thing.  Its the same as bringing it back to 25 square.

[Parker_Woodruff]

Quote: jetdriven

I tried a LOP climb in the 201 and it will do it, but the climb rate is so bad (<500 FPM,  105 KIAS, 10.0 GPH) that I dont think it saves a thing.  Its the same as bringing it back to 25 square.

[jetdriven]

If you only climb 2/3rds as fast, there is a tradeoff.  Even the TN Bonanza guys can't agree if it saves more than a galllon for the effort.

[Parker_Woodruff]

Quote: jetdriven

If you only climb 2/3rds as fast, there is a tradeoff.  Even the TN Bonanza guys can't agree if it saves more than a galllon for the effort.

[Parker_Woodruff]

Here's the LOP climb video after doing some GAMI flight testing with fantom...

http://www.youtube.com/watch?v=RkDkkw-tpQI&feature=youtu.be

[KSMooniac]

Quote: jetdriven

If you only climb 2/3rds as fast, there is a tradeoff.  Even the TN Bonanza guys can't agree if it saves more than a galllon for the effort.

[jlunseth]

Quote: KSMooniac

Will your K not run higher cruise power settings (like 75 or 80%, ~12 GPH LOP) at 50-60 LOP?  With the turbo you can always run more MP to restore the power.

[KSMooniac]

Disclaimer:  I have no experience operating a K engine

If it were me, I'd keep trying and start out by running experiments adding back MP at lower power settings (say 60%), go 30 LOP (quite conservative) and then add some MP back and record everything.  Then enrichen to find peak again, and re-lean to 30 LOP and see how it compares to what you originally set.  I think you could establish the behavior at a lower power setting and give you some confidence to do it at a higher power setting.  Also for the record, running the mixture in the "red zone" for enough seconds to find peak and re-lean is not going to make your engine crater, so I wouldn't fear running some experiments and recording data to work out a fuel flow setting to use going forward.

Good luck with the field overhaul too.

[jetdriven]

Why not set the mp 2" above the book power setting then lean past peak?

[donshapansky]

I have gone all through these gyrations with my Rocket. GAMI did tweak mine twice but it refused to run acceptably smooth and the TIT zoomed to 1700 before falling back but staying around 1650 or above so for 600+ hrs I ran ROP +120F to stay out of the never never GAMI band. Finally my Florida 50 hr major started to show higher oil consumption, darkening of the oil quickly after change elevated iron count and nickel count and 2 cylinders with a stepped leakdown on 2 cylinders.

I had Maxwell pull all the cylinders against advice and sent them to PowerMaster who agreed with Maxwell that the oil analysis didn't show enough problems. However there were 2 stuck rings, a broken valve spring and one tight valve guide. After finding the ECI cylinders to be straight and no wear they were all reconditioned and reinstalled. I have almost a year and over 200 hrs LOP with the TIT never hotter than 1575F, oil consumption is less than a quart in 35hrs and it stays golden in color.

Here is the settings: 2450 RPM @ 33.0 MAP 1570 TIT 15.5 gph - 16.3 gph depending on air density. Today at 7,500' OAT was 6C KTAS 192 kts. I regularly see 13 - 14 NMPG on the EDM930.

My old settings: 2450 RPM @ 29.0 MAP 1520 TIT 22.0 gph similar day as above 195 - 197 KTAS

I think I've saved around 1400 gallons this year with virtually no loss in speed! I know now that part of the equation is healthy cylinders, I'm sold on NIKISIL cylinders and would believe that TBO using the LOP method on the TCM is a realistic goal. Why the Lycomings run the TIT so hot I don't know but that is the limitation to regaining lost speed by increasing MAP.

Maxwell has seen the casting below the turbo on the Bravo completely eroded (maybe due to 1700F TIT) and it is a $4,000 part!