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Climbing Technique

logansc

Well Known Member
Dumb question, but I don't have any other RV guys right around here to ask and I've forgotten to ask when I've been at the few RV gatherings I've attended. How do you guys climb your RV's (mine is an IO-360 with c/s prop and an EDM-700)? Do you go full throttle to cruise altitude, pull it back to 25/25, 24/24, something like that, or what? What climb speeds are you using? Leaning during climb? I assume the anwers will vary from aircraft to aircraft with different engine/prop/monitor combinations etc, but there must be some "first principles" I should know about. Mine had been running very hot (CHT's, not oil temps), but I've recently sorted that out and I should be able to climb at full power now or close to it. Is that a good idea? Even to relatively high (8,000-10,000') cruising altitudes?

Thanks!

Lee...
 
We have a 6A - 0-360 - FP, but here's how we do it.

Full throttle from take off to cruse alt.
Start leaning after 3000 msl, must lean after 5000 msl (noticable loss of power above 5000 msl without leaning).
climb at 120 kts or faster to keep cht at or below 425 degs.

During the climb expect the rpm to be 2350 to 2450, CHTs around 425 and EGT around 1200, if rpm lower then 2350 you are to too rich, if rpm above 2450 pitch up a little.

:) We found over all during testing, plane at gross weight and OT at or above 85F, avg 1000 feet per min to 10,000 using the above.

We also use this chart mounted to our panel as a guide.
Altitude RPM Percent of H. P
2500 2550 75%
3500 2575 75%
4500 2600 75%
5500 2625 75%
6500 2650 75%
7500 2675 75%
 
Climb Techniques

Allen/Christopher: Good information, thanks for taking the time to respond. I will give your "plan" a try tomorrow! Thanks, and... Merry Christmas!!

Regards,

Lee...
 
I learned to fly with CS props back to 25/25 after gaining enough altitude to make it back to the runway (otherwise known as a safe altitude). Lycoming however will tell you that their engines are rated for 2700 max continuous rpm. With a fixed pitch prop (my -4 has 180hp and Sensenich) just shove it forward, the power will reduce as you climb anyway, and pulling it back won't help anything. If anything, the extra fuel flow will help cool the cylinders. I start at 5000' in Fort Collins, Co. anyway, so my takeoff rpm is pretty low even on a cold day! We lean for taxi (aggressively) then lean for takeoff, after climbing another 3000' feet or so, I'll lean a bit more.

Jeff
 
The wonderful world of C/S props

jhallrv4 said:
I learned to fly with CS props back to 25/25 after gaining enough altitude to make it back to the runway (otherwise known as a safe altitude). Jeff
Concur with Jeff. After Take off reduce throttle to about 24" and RPM to 2500 rpm for "25 squared." Note as you reduce RPM MAP will rise so set it first when reducing power and under shoot the target MAP slightly at first. After setting the RPM adjust throttle (MAP) as needed.

As you climb you keep shoving in the throttle to maintain the 25 squared (loose 1" MAP per 1000 ft climb), until the throttle is all the way in (around 4,500-5,000 feet). Leave the Throttle/Prop full forward until level-off. Leave mixture full rich in climb unless you are climbing well above 8,000 feet, than you may have to (must) lean slightly for smooth operation (if and only if well below 75% power).

Level off / cruise: Leave the throttle wide open (full fwd) and reduce RPM to smooth** operation (2300-2500 rpm). I say smooth because you may notice one specific RPM is smoother. Lean as required (if below 75% power).

Descend: just lower the nose and reduce RPM to 2300 RPM, if not already there (observe RPM limitation if any), trim. As you descend the MAP will rise, so keep reducing throttle a little at a time to maintain 21-22" max. You don't want to ever slam the throttle shut in decent and shock cool, so proper decent planning is needed with partial power. While maintaining 2300rpm and 21"-22" MAP during decent, there is usually no need to enrichen until you level off, usually entering the pattern on the down wind. Once the speed bleeds off after level off, bring the prop to high RPM (low pitch) and mixture full rich.

C-GUMPS:
Carb heat - consider checking or using as conditions dictate
Gas - Tank on fullest and pump on
Undercarriage - Down an welded (always do for the days you fly the retract)
Mixture - Rich
Prop - Full fwd, high RPM low pitch
Safety - seat-belts, lights
(repeat GUMPS at least 2-3 times silently, down-wind, base and final)

The slower you turn the prop in cruise the more efficient
The faster you turn the more HP (about 3-5 HP per 100 RPM) and more speed
Max climb is always max RPM, but 2500 rpm is "standard" for "en-route" climb
Observe any RPM limitations and don't operate continuously at those RPM's
 
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Thanks Again!

Great information, guys! I appreciate all the help. Just flew up to Fredericksburg, VA this past week and was using 25/25 during initial climb. I have not tried full power yet (hadn't read that response before I departed). The airplane climbed well but since I didnt' add throttle during climb, performance definitely fell off the higher I went. Added power at level off though and leaned to suit. Ran 22/23 at 8,500 and away we went! I'll see how she does on full power climb tomorrow. Happy New Year!

Regards,

Lee...
 
Wives tales

Someday, I'm going to take these guys course... But in the mean time, make sure you go thru the presentation on the top left of this link, and read the Deakin articles on Avweb (links provided on this pages as well).

Bottom line.

*do no pull the throttle back on climb out - why would you want to touch the engine controls at the most critical time in an engines life* - more in the reading.

Find your "target EGT" and lean to it at either the take off roll, or at about 600' above ground and continue leaning to altitude. Your engine will pay you back for doing this. This is also a *must* at High Altitude airports

While these guys are huge LOP fans, someday, I'll go there, but for now, they have a bunch of good info on the very types of procedures that you are looking for.

my .02,
Alan

Advanced Pilot Seminars - Assist page
 
Please clarify

aadamson said:
Bottom line.

(1)*do no pull the throttle back on climb out - why would you want to touch the engine controls at the most critical time in an engines life* - more in the reading.

(2)Find your "target EGT" and lean to it at either the take off roll, or at about 600' above ground and continue leaning to altitude. Your engine will pay you back for doing this. This is also a *must* at High Altitude airports

(3)While these guys are huge LOP fans, someday, I'll go there, but for now, they have a bunch of good info on the very types of procedures that you are looking for.

my .02, Alan

Advanced Pilot Seminars - Assist page
Yaaaaaa, I am a fan of Avweb but you are going to have to justify or explain these to me.

(1) Yes you should leave it WOT for the initial climb, but it is common to reduce "power" above a safe altitude. Heck if you are that worried that your engine would explode ofter a small change in the throttle you should not be flying. I might mention here since I did not say it before, all power changes are made slowly and smoothly. Keep in mind we have a C/S prop so the throttle will only reduce the temp and pressures in the combustion chamber. Yes reducing the the RPM from 2700 to 2500 changes the internal loads in the engines reciprocating mass (crank, rods, pistons, valve train, gear train) in the transition, but again do it slowly. I can't see this being a danger to engine health. May be this is a throw back to the Tiger Moth, Jenny days of the 30's or large compound radials of the 50's. Modern (healthy) small piston engines can handle a small power reduction. The real reason for waiting to 1000' in my opinion is you should be flying the plane, not monkeying with the throttle/prop.

I can't disagree with leaving the engine wide open except for FUEL, NOISE AND $$$$$$$$. Is there a reason to leave it WOT? To climb faster? Well if there was a great tail wind I was trying to get up into as quickly as possible or terrain, sure WOT full RPM is OK. Avweb is great but you have to be careful how you take it. Again reducing to 25"/2500 (25 squared) is common procedures.

In jets we go from T/O power to climb power; It is known that reduced climb may increase total trip fuel burn, but engine life and noise are factors. Jet engines love altitude (and cold temps) and become way more efficient, so the faster you climb the better. However it depends on weights, air temps and winds. Lycomings or any piston engine has the approx same efficiency at sea level as 18,000 feet. Yes fuel burn goes down, but that is a function of it making much less HP at altitude. The specific fuel used per HP is the same and not affected by altitude like a jet engine. WOT full power climbs do not present the advantage in a piston engine as it might with a Jet.


Yes a Lycoming can handle 100% power, 2700 RPM all day, but do you think it will last as long as one that is flown at 75% all the time or 2500 RPM? Lycoming indicates that reduce power improves engine life. I have no spacific data on engine life vs. climb power, but common sense says there is positive affects of reducing power, if nothing more than lower fuel burn and less noise. Since altitude does not make piston engines more efficient with altitude like jets, lower climb power and FF is equal to lower trip fuel burn.


(2) I find this statement to be dangerous and unclear. "Target EGT". What is that? My feeling is FOLLOW Lycomings recommendation, only lean below 75% power. Not sure what 600' altitude has to do with it, but if the suggestion is to start to lean at 600' (AGL?/MSL?) at take off power I say no. One never leans above 75% power. Also doing anything at 600' is not wise. On climb out to 1000' to 1500' don't do NOTHING but fly the plane. IN a RV this is not a long time. At the airlines if we have a mass engine failure at rotation we do nothing but fly the plane until 1000', when we deal with the emergency.


(3) Not sure what LOP has to do with climb and C/S props. To make comment many engines (small 4 bangers) are not capable of LOP operation because of many factors. Small engines (4 cyl) have less ability for LOP than 6 bangers or large radials. Factors like uneven balance of exhaust and intake mechanical characteristics, inherent between cylinders, for that engine installation make LOP unlikely to be practical for us. Most will find their engine will run too rough to run LOP. A few RV'ers claim to use LOP techniques on their 4-banger, but I think it is an exception. It is possible they may be doing damage. In theory LOP will have similar or lower temps than 100-150F ROP and should do no harm, but this is true only if done properly. LOP operations have been around for decades but for very large engines. Bottom line, this is cruise strategy not climb technique. The big draw back is if LOP ops are done poorly, you might unknowingly run some or all cylinders at peek temps, which is bad, if you don't know what you are doing. Also you need to have a FI engine and a well calibrated 4 channel engine monitor to do this.

Look forward to your response, Happy New Years, George
 
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Go read the info

Nothing trying to be rude or anything, but seriously, read the powerpoint persentation on "target EGT" on that link I sent, and also read the Deakins articles on "leaning". It will answer all your questions.... And Oh, BTW, you can run just about any engine LOP, injected's are easier, but Carbs (use carb heat to make it run LOP) work too. 4 or 6 cyl. And yes, an engine monitor helps a bunch!

this whole topic has one thing in common. Health of your engine. Read as less oil usage, less plug fouling, less wear and tear, more fuel effeciency, better power when you need it, and much better cooling.

I had a million and one questions as well, until I started researching this whole topic. I'm not trying to get into the LOP vs. ROP debate.... You asked about climb technique, and the powerpoint on "target EGT" is spot on to answer that topic. And the newer generation of engine management technique says, prop and throttle full forward and leave em until you are at altitude. Enroute climb is just setting the prop to climb pitch from then on.

Perhaps the one piece of info that I didn't mention. Of course, if you get to your altitude (with prop and throttle forward), and you still have more manifold pressure than you want to turn in cruise, of course, pull the MAP back as well. and set the cruise RPM.

One curve ball with "target EGT". You have to establish is at a "sea level" airport. So for example, the basic process is ... At a Sea level airport, take off with full rich mixture. At 600', look over and see what your peak EGT is. That's your "target EGT". Now "whenever" you climb, continue to lean to that number. No more, no less. Remember that number as you'll use if forever more. At each airport, regardless of airport elevation, set that number on climbout and continue to lean to it. At high altitude airports, during runup, lean as needed and on climbout, at 600', readjust to your Target EGT.

Hope this helps, it's new, its different, it's gonna get all kinds of "nay sayer" comments, but it has changed the way I fly.

Sorry for the LOP comment, didn't mean to confuse you. That's really a Cruise setting. One that I'm going to try one of these days.... BTW, the whole LOP topic, also has benefit on descent and ignore any comments about Shock cooling, unless you are running a turbo, you *can't* shock cool your engine! :)

Alan
 
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One other comment

gmcjetpilot said:
Yes a Lycoming can handle 100% power all day, but do you think it will last as long as one that is flown at 75% all the time? Lycoming indicates that reduce power improves engine life. I have no spacific data on engine life vs. climb power, but common sense says there is positive affects of reducing power, if nothing more than lower fuel burn and less noise. Since altitude does not make piston engines more efficient with altitude like jets, lower climb power and FF is equal to lower trip fuel burn.


George,

Just noticed one other flaw in your thinking (an affection flaw if you will :) ).

A Lycoming, or Contininental, never makes 100% power.... Actually, I suppose it does, at a specific sealevel altitude, temp, baro, but the likely hood of us ever being there is pretty slim.... So, as soon as you take off, in effect, altitude is lowering the power automatically.... so why touch the throttle lever. Use the power, and fuel cooling and prop effeciency to climb to where you want to go, and leave the black knob full forward...... with one exception, if you have an airplane, prop, and rpm that breaks the noise standards that some airports have, then yep, you 'll pull em back as needed.

Happy New year btw!
Alan
 
no problem but...

You are not being rude. You are only addressing item (2), "target EGT".

OK I looked at the power point presentation and one thing comes out. You are:

Running you engine HOTTER and longer.

You are violating Lycomings recommendation, no lean above 75% power (I think).

You can lean in climb and I like the "target EGT idea and have done that for years, but it really only comes into play above say 8,000-10,000 feet. I go for high altitude flight in the the lower mid teens sometimes and do lean as I climb. You have to or the engine will not run (well). I note the EGT at say 10,000', and as I continue to climb above 10,000' is start to lean to maintain the EGT.

What airplane are the AVweb guys using for their demo? RV's are tightly cowled and CHT is a big factor for some RV's. So to lean to "target CHT" may not be practical or safe. Again I hate to be a old fuddy duddy and say "STICK TO THE MANUFACTURES RECOMMENDATIONS", but I will. Lycoming recommends that for longer engine life do not exceed 400F CHT. Again like LOP it may not be practical, not to mention the BIG increase in pilots work load. While you are staring at the engine monitor are you looking for traffic. I guess if you can get a flight engineer sitting in the passenger seat they can lean in climb.

It is nice info and fancy presentation, but I am not sure how practical it is. For high altitude takeoff, Denver in standard conditions may be a place where you need to and should lean slightly for take off. You can do a runup and lean to rough and enrichen for smooth operations, as Lycoming explains. I can see the "target EGT" method and memorizing some target is a good technique also, but it is a variation on what we always have done, just an adaptation since fancy engine monitors with all cylinders monitored are more common. I can tell you and you know this, for decades and decades GA and most commercial aviation flying piston engine planes have lived just fine without engine monitors or even a single channel EGT or CHT for that matter. Knowing (approx by map/rpm) you % power and leaning to rough and enrichen works.

I have an engine monitor and agree new techniques and "target EGT" methods will improve efficency slightly; however I would rather burn a gal of gas and keep my CHT's a little cooler in climb. Also this takes constant attention and manipulation of the mixture. IS this practical. Some pilots have a hard enough time flying the plane, talking on the radio and looking for traffic (I hope) and even leaning the engine at all, much less every minute.

Thanks for the info. I learned a little but don't think it will change my practice of reducing to 25 squared as standard procedure and leaving the mixture rich in climb until above 8-10K.

George
 
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Tell ya what

George,

I'm not trying to change your habits.... But, I do think you are letting the "old school" get in the way of a better procedure.

There are several things that hurt your engine. Heat is just one, and oh, btw, it's not the worst one.... ICP (internal cylinder pressures) is also one, as is carbon, and lead, detonation, etc. The ability to keep a "perfect" (which you never can do, so let's just try to adequate), fuel to air ratio (F/A), is much better for "all" the engine dynamics than relying on "old school" ways of doing things. BTW, watch your CHT's, not your EGT's using your method vs. the Target EGT method then let me know which is "cooler" :)...

Let me quess, you also, only adjust the prop and throttle in a given order on climb and reverse that order on descent? There is no reason to do this. Most of these wives tales were taught as a result of the radial engines that were used back in the dark ages. Horizontally opposed engines don't suffer from the same problems that the Radials did. But for some reason, the wives tales continued.

I'll offer one other comment.... Don't think that just because you have an RV, that it's the best at baffle efficeincy, etc. There are lots better, plenum baffles come to mind. I have a Lancair Legacy (about a tight as you can get an IO-550 in) and a 2004 Cessna 182. Both are extrememly well baffled.

Finally, as for the Lycoming procedures, and just to show you how different things are.... My new 182, with a Lyc IO-540 in it, specifies that I lean from take off to altitude, in fact, it gives me target fuel flows for max power from 0 to 15K on a little placard in the cockpit. :)...

Thanks for a non-confrontational discussion. I'd only offer that you be open minded and try a few things. Manuals are just that, suggestions - as noted by my Lycoming IO-540 :)...

Take care, and happy new year.
Alan
 
That's all folks

aadamson said:
George,

Just noticed one other flaw in your thinking (an affection flaw if you will :) ).

A Lycoming, or Contininental, never makes 100% power.... Actually, I suppose it does, at a specific sealevel altitude, temp, baro, but the likely hood of us ever being there is pretty slim.... So, as soon as you take off, in effect, altitude is lowering the power automatically.... so why touch the throttle lever. Happy New year btw!
Alan
Happy new years. This is another issue, Item (1) if you will.

I agree leave it wide open if you want; If you want more noise and fuel burn. I stated my reason for going to 25 square. lower FUEL burn and noise. Unless there is some strong incentive like a tail wind aloft, shorter time to climb and the greater fuel burn is not advantageous. The faster you get there the quicker and longer you can take advantage of the winds.

In my RV-4, 2500 rpm was smoother and less noise, not really an efficiency thing. So it is not as much a flaw in my perfect logic :rolleyes: but a preference. It is much more about noise and comfort then % power. Also 2500 rpm is less wear and tear on the engine than 2700 rpm. Is it a big deal? Naw and I race sometimes and run WOT and full RPM when I do.


Fuel burn to cruise will not doubt be higher if you leave T/O power (settings) all the way to climb. You will get there sooner but is it worth it? It is like reducing RPM to 2300. You will go slower and the trip time may be longer but you might burn less fuel. I say might because if there are strong head winds you may want to fly faster.

Also as I said on a hot day some RV's run toasty CHT's and a power reduction might help, that is all. Again as far as leaning in climb you have a better chance of burning a valve than saving fuel in my opinion. An exhaust valve cost $350, plus the time and effort to remove and replace it. You may be outsmarting yourself with these techniques, WOT full RPM climbs and aggressive leaning. I would rather burn a little more gas to keep CHT down, that's all folks.

Thanks again you got me thinking and a slight different approach in climb power and leaning in climb is worth a look. It is up to the PIC, it clearly has merit. I think in big engine planes with IO540's, leaning procedures are more critical, produce more savings, which changes the picture a little. However in a little O360, there is a diminishing return on these strategies, with some potential down sides. I stick with the old no lean above 75%. I wounder what the deal is with your C182, if there is a differnce in that model.

I might call Lycoming and talk to them. If the engineer has any insight I'll pass it along.


George

BTW I am jealous you have a new C182 and Legacy! RV tooo? Boy that must be nice. Let me know if you need me to help you fly your planes, you know to keep the dust off them. :rolleyes:
 
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Nah

Nah, no Rv's.... I just lurk over here as you guys have some good ideas about stuff...I'm actually in the middle if building my Legacy.... It's a little unique. It will be a Carbon Fiber version built on the RG platform, but with FIXED GEAR. There is only one other like this currently built (altho they do sell this as an option), but it's going to Italy in the spring.

The RG cruises at 240kts, and based upon the one like mine that is flying, it was crusing at 225kts with no paint or body work. It should get a little faster with paint and body work. The designer believes that an FG will only be 10-12kts slower than the RG.... I can live with that and no RG maint headaches. I couldn't find an RV that I could build in 10 wks, that would cruise at 250mph, and would climb at full gross at 2500'/min and I do use and airplane for travel.

Unlike most Legacy's, I can build this one for around 150K. Actually, I could build it for way cheaper, but I am going to put the Chelton dual screens in it. After flying behind the G1000 in the 182, I don't think I can go back to steam gauges.....

But then I'm only 45, been licensed, for 12 years, so I guess you'd call me one of the "new generation" of pilots... Hence my willingness to try new things and I don't have the "old school" indoctrination :)...

Where's home? I'm in ATL, at LZU...

Alan
 
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gmcjetpilot said:
Again as far as leaning in climb you have a better chance of burning a valve than saving fuel in my opinion. An exhaust valve cost $350, plus the time and effort to remove and replace it. You may be outsmarting yourself with these techniques, WOT full RPM climbs and aggressive leaning. I would rather burn a little more gas to keep CHT down, that's all folks.

Thanks again you got me thinking and a slight different approach in climb power and leaning in climb is worth a look. It is up to the PIC, it clearly has merit.

Here, in Salt Lake City at 4200', it's standard practice to lean after engine start as well as re-adjusting before takeoff. The amount of available power "loss" for the takeoff is very noticeable between full rich and leaned. Lack of leaning around here, usually by coastal area pilots, has been an contributing factor to numerous accidents.

Since we're leaning by necessity at 4200' (+ density altitude) to begin with, I don't believe I've seen a rash of burned valves in this area. :)

L.Adamson
 
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We related?

Ok, seeing as I'm from Roosevelt, and my last name is Adamson.... We must be related somewhere along the food chain???

Alan - Adamson
 
aadamson said:
Ok, seeing as I'm from Roosevelt, and my last name is Adamson.... We must be related somewhere along the food chain???

Alan - Adamson

I'm originally from Twin Falls, Idaho, as is most of my immediate family. And BTW, I 100% agree, regarding glass panels such as the Garmin 1000, Chelton, etc. They ARE the future!!! :D

L.Adamson
 
Voices of experience

The voices of experience. I lean very aggressively when taxing all the time. Before shut down I do a short leaned run up and lean just before roughness, throttle back to idle, then lean to cutoff for shut down as usual.

Now the question is can we do better with engine monitors? Sure, Lycoming writes all this based on the fact most have no EGT, CHT and FF.

I cut and pasted some of their "Key reprints" regarding leaning and climb power.

So I have been enlightened by the previous post and see where the "target EGT" concept has validity. I have used EGT for years at altitude but did not call it target EGT. I may have been too conservative by not leaning until well below 75%, but I still will not lean above 75% power. Where does 75% come from? I believe it has to do with detonation margins. Again trade a little fuel for margin of safety to engine damage, engine monitor or not. Once you know your plane you play the mixture control like a slide trombone, you know where it needs to be for the right musical note, or mixture in our case.


From Lyc:

Climb requirements may vary; as an example, on a warm day with the airplane close to gross weight, and a direct drive engine with a fixed pitch prop, the pilot will need full throttle all the way to cruise altitude. The same airplane on a cold day and lightly loaded may not Like you require full power for climb. After full throttle at takeoff, the pilot may want to reduce power 100 or 200 RPM and still not see performance suffer.

Those direct drive normally aspirated engines with a prop governor are also rated indefinitely at full power, and the manuals all recommend full power for takeoff, but specify a small reduction in power, generally to 85% power climb. Study the specific airplane Pilot?s Operating Handbook for detailed power settings.


AND

Pilots frequently ask us for information and guidance concerning landings and takeoffs from high elevation airports. Our reference point in this discussion will be based on density altitude. The discussion also requires that we treat separately operation of normally aspirated, turbocharged, and supercharged engines at high elevation airports.

NORMALLY ASPIRATED

The normally aspirated engine performs and reacts to density altitude. As an example, this type power-plant at takeoff from an airport with an indicated altitude of 3,000 feet, but with an ambient temperature at 85oF, would have a density altitude of more than 5,000 feet. The engine would lack some 20 to 25% of its power and also probably run rough because of a rich mixture on the ground at full rich. Therefore, the typical normally aspirated direct drive engine requires the mixture be leaned on the ground for efficient takeoff performance where airports are 5,000 feet (density altitude) or higher. The over-rich condition is something the pilot can compensate for by leaning. However, the higher density altitude with its thinner air cannot be compensated for with a normally aspirated engine unless a supercharger or turbocharger unit is added to the power-plant. Thus, at density altitudes of 5,000 - 6,000 feet, the pilot of a normally aspirated engine has available to him approximately 75% of the engine power, and must plan his takeoff accordingly after setting the mixture.

PROCEDURE FOR LEANING

1. The fixed pitch propeller - lean to maximum RPM at full throttle prior to takeoff where airports are 5,000 feet density altitude or higher. Limit operation at full throttle on the ground to a minimum time.

2. The direct drive normally aspirated engine with a prop governor but without a fuel flow gage, set throttle at full power and lean mixture at maximum RPM with smooth operation of the engine as a deciding factor.

3. With fuel injection, if the power-plant has a marked fuel flow gage, then set mixture in accordance with instructions on the fuel flow gage and/or in accordance with the airplane Pilot?s Operating Handbook.

DESCENT

Regardless of the field elevation where the pilot intends to land, the descent from cruise altitude to traffic pattern altitude should be made with the engine leaned for smooth engine operation. Low elevation fields (below 5,000 feet density altitude) will require that the mixture be moved to full rich in the "before landing checklist". Landing at airports above 5,000 feet density altitude, the mixture must be leaned to smooth engine operation during traffic pattern flight and landing; otherwise, the engine may stop on the runway because of excessive richness.


AND

A. GENERAL RULES

1. Without exception, observe the red-line temperature limits during takeoff, climb and high performance cruise power operation.

(a) Cylinder head temperature - maximum limit listed in the Textron Lycoming Operator?s Manual.

(b) Oil temperature limit - maximum limit listed in the Textron Lycoming Operator?s Manual.

2. Whenever mixture is adjusted, rich or lean, it should be done slowly.

3. ALWAYS RETURN MIXTURE SLOWLY TO FULL RICH BEFORE INCREASING POWER SETTING.

4. At all times, caution must be taken not to shock cool the cylinders. The maximum recommended temperature change should not exceed 50oF per minute.

B. LEANING THE NORMALLY ASPIRATED ENGINES

1. Use full rich mixture during takeoff or climb. Careful observation of engine temperature instruments should be practiced to ensure limits specified in Textron Lycoming operator?s manual are never exceeded. Refer to the aircraft POH (pilot?s operating handbook) or AFM (aircraft flight manual) for more specific instructions.

2. For 5000 feet density altitude and above, or high ambient temperatures, roughness or reduction of power may occur at full rich mixture. The mixture may be adjusted to obtain smooth engine operation. For fixed pitch propeller, lean to maximum RPM at full throttle prior to takeoff where airports are 5000 feet density altitude or higher. Limit operation at full throttle on the ground to a minimum. For direct-drive, normally aspirated engines with a prop governor, but without fuel flow or EGT, set throttle at full power and lean mixture at maximum RPM with smooth operation of the engine as a deciding factor.

3. For cruise powers where best power mixture is allowed, slowly lean the mixture from full rich to maximum power. Best power mixture operation provides the most miles per hour for a given power setting. For engines equipped with fixed pitch propellers, gradually lean the mixture until either the tachometer or the airspeed indicator reading peaks. For engines equipped with controllable pitch propellers, lean until a slight increase of airspeed is noted.

4. For a given power setting, best economy mixture provides the most miles per gallon. Slowly lean the mixture until engine operation becomes rough or until engine power rapidly diminishes as noted by an undesirable decrease in airspeed. When either condition occurs, enrich the mixture sufficiently to obtain an evenly firing engine or to regain most of the lost airspeed or engine RPM. Some engine power and airspeed must be sacrificed to gain a best economy mixture setting.

NOTE

When leaned, engine roughness is caused by misfiring due to a lean fuel-air mixture which will not support combustion. Roughness is eliminated by enriching slightly until the engine is smooth.

5. The exhaust gas temperature (EGT) offers little improvement in leaning the float-type carburetor over the procedures outlined above because of imperfect mixture distribution. However, if the EGT probe is installed, lean the mixture to 100oF on the rich side of peak EGT for best power operation. For best economy cruise, operate at peak EGT. If roughness is encountered, enrich the mixture slightly for smooth engine operation.

6. When installing an EGT probe, the probe must be installed in the leanest cylinder. Contact the airframe or kit manufacturer for the correct location. In experimental or custom applications, multiple probe instrumentation is required and several power settings should be checked in order to determine the leanest cylinder for the specific application.

7. During normal operation, maintain the following recommended temperature limits:

(a) Cylinder head temperature - limit listed in the Textron Lycoming Operator?s Manual.

(b) Oil temperature - limit listed in the Textron Lycoming Operator?s Manual.

8. For maximum service life, maintain the following recommended limits for continuous cruise operation:

(a) Engine power setting - 65% of rated or less.

(b) Cylinder head temperatures - 400oF. or below.

? Oil temperature - 165oF. - 220oF.
 
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Re: Deakin

Without trying to stir things up too much more I always wondered about Deakin. IIRC he was a big advocate of running oversquare as well. I exchanged a couple emails with him a couple years back after reading a couple colums and I was basically told, Run WOT, set your power with the Prop, and LOP. I think he told me that you need FI and an engine moniter to do it properly as well. FWIW It looks like his last regular Avweb article was over 2 years ago.
 
That is cool

1911pilot said:
Without trying to stir things up too much more I always wondered about Deakin. IIRC he was a big advocate of running oversquare as well.
Lycoming addresses and its cool. It was an old wives tale not to run over square. There are limitations and Lycomings key reprints talks to this:

http://www.lycoming.textron.com/mai...ions/keyReprints/operation/powerSettings.html

and

http://www.lycoming.textron.com/mai...ons/keyReprints/operation/lowPowerLowRPM.html


and the link given before for all key reprints (above come from operations):


http://www.lycoming.textron.com/main.jsp?bodyPage=support/publications/keyReprints/index.html


George
 
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