Reduced power Take Offs?

Given that short take off and landing distance is baked into RV's, has anyone tried to quantify a way to take off using less than full power since many runways are long enough to do a couple of stop and go's?

All my Air Force flying (T-38s and F-111s) was done with full afterburner regardless of the actual runway available; but maintenance was free and we had ejection seats. Now in the airlines, we almost NEVER use full power for take off, preferring to save the engines and money.

Airliners reduce power by tricking the engines into acting as though the outside air temperature was higher than is actually is, therefore producing less thrust. Extensive calculations are on the books to ensure these reductions still allow sufficient thrust to meet all FAA climb requirements.

Couldn't some of the more sophisticated electronic injection systems and EFIS systems do these calculations? Since the weight of an RV doesn't change to the degree it does on airliners, I believe all we'd have to worry about is runway length and pressure altitude.

Of course, reducing take off power might not allow one to fly beyond TBO (although it might be worth asking that question) but if you can operate safely and go easier on the motor, why wouldn't we?

I'll now step back and let the smart types step up to the mike.

Take offs

Why ????? What good can come from it ?

There was a good discussion about that couple years ago http://www.vansairforce.com/community/showthread.php?t=66824&highlight=reduced+power

I do it on a regular bases

I used to take off with my RV-4 at approx 23 inches and with the -10 I use 25 inches a lot of the time.

I don't push the peddle to the floor on my vehicles every time I take off.


On the Fisher Classic I sometimes complete the entire flight going no more than 1/2 throttle which is about 2700-2800 rpm. Full throttle on the VW is 3400-3500 rpm. Its just a lot of unnecessary commotion for normal operations.

The purpose of take-off is to get positive distance between you and the ground. Not too worried if it means 100 less hours before TBO. I like the extra safety (in my mind) of getting to pattern altitude as quick as possible where you have options. I have no data that supports it is safer nor do I have any data that indicates I am using up engine life by doing full power take-offs.

Old saying is what comes to mind
"Things which do you no good in aviation: Altitude above you. Runway behind you. Fuel in the truck."

How would the airlines handle takeoffs if they flew single-engine aircraft?

claycookiemonster said:

..........snipped..........

Airliners reduce power by tricking the engines into acting as though the outside air temperature was higher than is actually is, therefore producing less thrust. Extensive calculations are on the books to ensure these reductions still allow sufficient thrust to meet all FAA climb requirements.

.......snipped.........

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I thought that the performance calculations of reduced thrust was to meet balanced field requirements (accelerate stop), while assuring second stage climb beginning at 35'.

I never could figure out how they came to arrive at those numbers. As it always appeared to me that if we lost one just shy of V1, we were going to be touring the airport perimeter roads!
Checked out your blog, Clay. Very fun reading!

On gravel surfaces take off is initially done with a very reduced power setting to get rolling so the prop does not get chipped. About the time the TW lifts 2-4 inches (and holding that attitude), power is then smoothly ramped up as airspeed increases but I don't even think about full power until airborne, and then there is seldom any need unless clearing trees. It sounds like it hoses a lot of runway, but it is still quite short in an RV.

Airline wise, I recently had a ride in a Lufthansa 737. Now that was one FULL power event before brake release with back slamming acceleration from an intersection take off !!

I'm not sure that the full-power aspect of take-offs is what causes our engines much harm. It seems much more of the wear comes from cold starts, not allowing oil to warm up before T/O, and thermal shocks from either advancing or reducing throttle too quickly. Managing temperatures seems to be much more important that avoiding full power, which most of our engines were designed to run at indefinitely. They say (whoever "they" are) that our engines would go many times past TBO if they ran continuously rather than having to deal with cold starting and temperature changes.

I don't know a thing about jets, but perhaps their wear is more directly related to power production.

Chris

It's not a bad idea to practice low power take offs. Exploring the bottom end of that envelope develops skills. Nice to have in your tool box.
As an example, don't make the first time you need those skills be when your hot, high, and heavy and have no excess power to bail you out.

Full Power!

With all aircraft engines, use full available rated takeoff horsepower for all takeoffs. I cannot think of a single exception. You are usually not being kind to your engine when you use less, and you may very well be mistreating it when you do so. I see warbird operators using a lot less power all the time, and I think they're wrong. You can tell 'em, but you can't tell 'em much. If the engine manufacturer has published data for an alternate power setting for takeoff, that's fine, too. Otherwise, stick to the full rated power. That means full throttle (for normally aspirated engines), full redline RPM, and mixture full rich at sea level, or leaned appropriately for altitude.

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Quote is from John Deakin and is what I have been taught and practiced.
I see a lot of RV pilots using less than full rated engine power for take off on the mistaken believe that they will somehow baby the engine past TBO in this manner.
Those who notice black oil are seeing the result of blowby and overheating due to all the reasons mentioned above.

I do however reduce power a couple of minutes after take off and although some would have you believe that leaving the throttle fully open and simply reducing RPMs is the way to go, I am not buying it. I understand the minimal reduction in power output due to pumping losses with a partially closed throttle.
On a 1 hour trip I frequently fly I have tried both approaches, that of simply reducing throttle and RPMs ( my conventional style) and that of leaving the throttle fully open and reducing RPMs only.
The latter approach saves a minute or 2 in flight time but uses 5 gallons more gas for the same 2 hour round trip. LOP any part of the trip using 65% power or less.

During training, we did low power takeoffs to simulate high density altitude conditions. Most all my flying is done at sea level -- almost never more than 500' DA. It's interesting to see how "poorly" the plane performs at 10,000!

...wait for it ... wait for it.......

A couple of things...

As to how airlines would do things if they flew single engine aircraft; I bet they'd take really good care of that engine! If you were flying in a single engine airliner, would you be concerned to learn that they'd been using full power for every take off because of the thrill they got from the acceleration?

For the moment, count me as skeptical that somehow in horizontally opposed aircraft engines, using less than the full power available is actually bad for the engine. Seems to me that for every other mechanical object and engine I can think of, going a bit easier and staying a bit further from the redline is usually wise, but I'm willing to learn.

Finally, getting lots of altitude as quickly as possible may or may not be a good idea. That would seen to vary with the situation; people die trying to turn back to the airport because they've gotten too high and gone too far and there's no place to land ahead of them. Perhaps it would have been better for their failure to have occurred at 50' rather than at 1500'?

Using less than the full thrust the engines can produce was very non-intuitive for me too, however after years of doing it the airline way (and even the Air Force began doing less than full afterburner take offs in later fighters) for years now, I'm still wondering why we're straining metal more than required. 6G turns are fun too, but we don't do all our turns that way.

As a Flight Engineer, all of my takeoff computations in the E-6B were reduced thrust, unless limited by an climb requirement or field length.

The biggest contributor was not to extend time between required maintenance. It was just a fact that a majority of turbine engine failure happen when the engine is operating near max operating speed. While I don't have the data to support it, I would believe that the majority of catastrophic recip failures probably fall within the same regime.

The argument to use full power to climb to pattern altitude as quickly as possible is valid. However, you have to remember that potential energy, i.e. altitude, is only part of the equation. It's a combination of kinetic and potential that you're trying to achieve.

Not saying that partial power is the right answer... But I do believe that it's does have some merits.

Weasel said:

I don't push the peddle to the floor on my vehicles every time I take off.

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Boy, you're missing out on a lot of fun!

MercFE said:

It was just a fact that a majority of turbine engine failure happen when the engine is operating near max operating speed. While I don't have the data to support it, I would believe that the majority of catastrophic recip failures probably fall within the same regime.

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I have heard piston engines typically fail at the application of power or during power changes. Not necessarily max power. I've never really researched it too thoroughly though.

-Tim

Interesting question Clay. I doubt we'd be hurting the engine with reduced power takeoffs (except perhaps in a carbed setup where the full-power enrichment feature may not be doin' its thing), but I also wonder if there is value. I'd love to hear from engine experts (recipe and turbine) as to the relative value to engine wear in each engine type (recip vs turbine).

At work the reduced thrust takeoffs are an economic contract with engine manufacturers or lessors. Engine costs contractually decrease when reduced power takeoffs are used?that's one reason why we have to log full power takeoffs. I'm confident the economics stem from engine life improvement, and have always assumed it was temperature related?low airflow through a high bypass turbofan, while the turbine section is screaming up to speed and getting very hot, seems to me the primary motivator for reduced thrust takeoffs. As another poster mentioned, it could be compressor and turbine speeds, and associated bearing life as well. Any GE, RR or CFM guys out there with the straight scoop?

Another interesting aspect of transport reduced thrust takeoffs is that the reduction is eliminated at some point following takeoff (5,000', 105 seconds, or other trigger points), and a normal climb power setting is resumed for the climb to cruise. That supports the low-speed, high power = wear equation, and also indicates that the economics of reduced power takeoffs is overcome by the economics of getting to cruise altitude at some point, and fairly early in the climb.

In recips, although its true that aircraft speed and cooling flow make a difference in CHT and Oil Temp, I'd be interested to learn if the temps are as sensitive to reductions in takeoff power. And if you compare it to jet ops, if you do reduced power takeoffs, is there a point where its better to push the power up and get to cruise altitude and speed. Just some thoughts for discussion.

I also wonder how the runway length and climb performance is affected (comparatively), in FP versus CS props. I would think FP props might suffer a bit more in this scenario, but not sure.

My guess is you would not use reduced power if runway length, obstacles or climb gradient requirements were a factor. You'd probably only use them when you had very clear performance margins. Probably wise, since at work there is a lot of supporting airport analysis and performance data for reduced thrust takeoffs, and I doubt many recips have such data for runway length and climb over an obstacle. Of course, engine out second segment climb gradient that impacts the flap setting and power setting calcs at work is not a player for us, since there is no climb, in any segment, if we lose the motor!

It would be interesting to hear more on this. I typically am at WOT from takeoff to some point in the descent (if needed to control speed). I do reduce RPM in climb for noise in most cases, but the black knob stays in. Just one technique.

Would love to hear if there are valid cost, recip engine life, or other reasons that reduced power takeoffs or climbs are good to use. Deakin doesn't seem to think so. I can see gravel as a motivator for reduced power initially, with all ya got once you're going fast enough that the gravel can't catch ya!

The thread that Vlad referenced has a lot of this discussion too. Interesting topic!

Cheers,
Bob

One advantage of reduced power takeoffs is less noise, which can help or even be required at small private strips. Formation takeoffs by definition are reduced power as well...

I have a vernier RPM control, so know that 2 turns back is ~2500RPM say, and will then set say 25"-26".

It's a balance between various factors, and I doubt there is any correct answer re safety, TBO, runway length. I would be reluctant to encourage others to do it if they were at all uncertain or inexperienced.

Clay,
I am a little surprised by the reduced powe takeoff of airlines... You mean you do not calculate runway performance for temp and airport altitude for take off and use the power computed that will give you the maximum acceleration to V1 and give you the maximum runway left for an stop from V1?

We do in our jets!

As far as piston. Max power gives you max oil pressure also for max flow for cooling of the aircraft engine at higher AOA at takeoff.max fuel flow also for cooling..and maximum altitude for safety for a given condition...

I do not believe you save anything with a reduced power takeoff.
Jack

N427EF said:

I do however reduce power a couple of minutes after take off and although some would have you believe that leaving the throttle fully open and simply reducing RPMs is the way to go, I am not buying it. I understand the minimal reduction in power output due to pumping losses with a partially closed throttle.
On a 1 hour trip I frequently fly I have tried both approaches, that of simply reducing throttle and RPMs ( my conventional style) and that of leaving the throttle fully open and reducing RPMs only.
The latter approach saves a minute or 2 in flight time but uses 5 gallons more gas for the same 2 hour round trip. LOP any part of the trip using 65% power or less.

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Are you getting high enough to run LOP on the "leave the throttle in" flights? I'd imagine that's going to make the biggest difference in your fuel burn.

rvmills said:

At work the reduced thrust takeoffs are an economic contract with engine manufacturers or lessors. Engine costs contractually decrease when reduced power takeoffs are used?that's one reason why we have to log full power takeoffs. I'm confident the economics stem from engine life improvement, and have always assumed it was temperature related?low airflow through a high bypass turbofan, while the turbine section is screaming up to speed and getting very hot, seems to me the primary motivator for reduced thrust takeoffs. As another poster mentioned, it could be compressor and turbine speeds, and associated bearing life as well. Any GE, RR or CFM guys out there with the straight scoop?

Another interesting aspect of transport reduced thrust takeoffs is that the reduction is eliminated at some point following takeoff (5,000', 105 seconds, or other trigger points), and a normal climb power setting is resumed for the climb to cruise. That supports the low-speed, high power = wear equation, and also indicates that the economics of reduced power takeoffs is overcome by the economics of getting to cruise altitude at some point, and fairly early in the climb.

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Spoke briefly to a friend at GE, and looked through some documentation I have laying around... basically, turbine engine life is a function of temperature and time spent at that temperature. The more time you spend operating close to or at your temperature limits, the shorter the engine lasts.

An interesting example is the F414* upgrade GE is pitching to the Navy. The proposal upgrades the hardware, giving a small fuel burn reduction and improving the lifetime of the engine. Or, the engine can be run at a higher thrust setting, but dramatically shortening the engine's lifetime.

That's why the reduced-thrust takeoffs are so popular--even a small reduction in turbine temperature leads to a longer engine life.

I wasn't aware that climb settings sometimes resulted in thrust increases, though--I was always under the impression that takeoff thrust could not be lower than climb thrust. I suspect the difference in such cases isn't airflow through the engine, but rather the temperature of the air coming in (the warmer that air is, the less "room" you have before hitting a temperature limit).


*The F414 is the engine used on the Super Hornet

In a Single screw, altitude and airspeed is my safety net. Reducing power while coming off the ground will neither provide airspeed or altitude as quickly as full power (for me at least to 800' AGL). Reduced power takeoffs in single engine extend the time flying within that "no-return" window. Its well worth it to me to allow the engine to provide it's fully rated power and get me out of the "danger zone" as quickly as possible. These things are tractor engines, not porcelain doll

On the inverse... coming in and recovery to the runway: I hate being slow and low! If I am ever able to take a break over the runway into a circling approach... I do it or ask for it. I always try to play nice with others (C152/C172 trainers). SA is the key, you can "time it" with traffic normally. 1000' traffic pattern I can be slow, breaking that I better be glide distance to rwy or smoking fast with all kinds of energy to zoom climb above my personal 800' agl number.

N546RV said:

Boy, you're missing out on a lot of fun!

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I know. I remember when I was driving my parents vehicles. .......

claycookiemonster said:

As to how airlines would do things if they flew single engine aircraft; I bet they'd take really good care of that engine! If you were flying in a single engine airliner, would you be concerned to learn that they'd been using full power for every take off because of the thrill they got from the acceleration?

For the moment, count me as skeptical that somehow in horizontally opposed aircraft engines, using less than the full power available is actually bad for the engine. Seems to me that for every other mechanical object and engine I can think of, going a bit easier and staying a bit further from the redline is usually wise, but I'm willing to learn.

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It does seem intuitive that engines wear faster at higher power, but what is intuitive is not always true. Based on all I've ever read and heard, I believe that this is not the case for piston aircraft engines, which are designed to run at or near full power for their entire life. A car or other ground based engine may not perform the same way.

My point about the airlines (meant to stimulate discussion) was that they can afford to operate at less than full power (meaning reduced climb and more time closer to the ground) because they have the luxury of multiple engines. If the whole scheme was based on one engine, I suspect the risk/ reward math would have them going full power all the time to climb as quickly as possible to get away from the hard ground sooner.

I'm looking at this purely from a safety of flight viewpoint. Noise, high altitude practice etc. are issues but less important than safe operations.

Good discussion.

A warbird friend of mine said they used to use reduced power on takeoff until they realized they were eating up cylinders. Now they use full power and full rich until they are about 1000' AGL. Then they set up cruise climb to their cruising altitude.

I wonder if Doug R. can confirm this.

Lycoming says...

Full power should be used for all takeoffs.
The issue is that the increased fuel flow helps cool the cylinders when there is little airflow over them. Take offs with partial power will shorten the life of a ;piston engine.

Full burner in the T-38 and B-1 was too much fun, especially on a cold day!

Scott A. Jordan
80331
1000+ hours

The airlines use an assumed outside air temperature. By pretending that it is as hot as the charts allow for a safe takeoff, they find a thrust setting that will still meet the balanced field requirements. They did this even in the piston days. I'm convinced that it does reduce wear. However the safety of altitude in a single engine airplane seems pretty important too. I will admit to doing reduced power take offs in RY from time to time. I still remember my CFI's words of wisdom "slow is smooth, smooth is fast, less is more...." he was a real zen kinda guy.

Maybe just generally?

The airline and engine manufacturers have spent uncountable engineering hours calculating the procedures and economics and confirming the safety of using reduced power on take off - we're unlikely to have that time or expertise or maybe even the data.

Trying to come up with even a simple reduced power plan for RV's is both simpler and more complicated than it would be for the airlines.

1. The airline version needs to address the possibility of continuing a take off after an engine failure; the classic V1 cut. In an RV, if the motor quits, we're just going to stop.
2. A 737 could, at best, get airborne in about 3000 ft. If we operate from a 10,000' runway, we're using 1/3 of the concrete. An RV can be airborne in 500', if it's on a 5000' runway, it's only using 1/10th of the runway! Given our lack of computing power and data, it's comforting that we can do a simpler job and be confident that margins are still in place.
3. Our complication is that no two RV's are the same, however during Phase I there is time to do many take off rolls and note time/distance to take off and "safe" altitude and arm ourselves with our own data.

Perhaps the engine guys could chime in here with information on operation at reduced RPM/MP?
I'd assume "blow by" would be a factor of combustion chamber pressure, is that pressure significantly reduced when operating at lessened RPM?
I'd also like some information on how much engine cooling is accomplished by full throttle/ full rich operation. I'm not much of a piston guy, is this a known and proven thing or urban legend?

I'm not sure I understand what the attraction of a low powered takeoff is.

Is it to save some money somewhere down the line?

If so, let's think about this. We invest tens of thousands of dollars into these planes, we prime them in the unlikely event they'll turn to dust around us, we invest the kids college fund in an instrument panel when, really, all we need is an airspeed indicator.

And we're going to be cheap on the first thing of actually flying that might kill us?

If that's not the point, I need to hear more.

Because the only thing I care about is getting to an altitude that I can turn back with an engine failure just as quickly as I possibly can.

LettersFromFlyoverCountry said:

...We invest tens of thousands of dollars into these planes, we prime them in the unlikely event they'll turn to dust around us, we invest the kids college fund in an instrument panel when, really, all we need is an airspeed indicator.

And we're going to be cheap on the first thing of actually flying that might kill us?

If that's not the point, I need to hear more.

Because the only thing I care about is getting to an altitude that I can turn back with an engine failure just as quickly as I possibly can.

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I couldn't have said it better

Engine failure

I'm no expert but I did drive race cars for a few years. Granted, they were very different from our Lycomings and driven very hard usually at redline as long as possible. Every failure I saw or experienced seemed happen coming off a high speed straight. Boom, oil all over the place. Never once saw a failure on hard a acceleration.

The R-3350 from the piston airliner days has very little in common with a 4 cylinder Lycoming.

In any supercharged radial I've ever been around, full throttle is above the manifold pressure redline. Full throttle and full power are rarely the same. Back in the days of multiple grades of avgas, there would be different MP limits based primarily on fuel being used. Piston airliner reduced power take-offs will have more to do with turbo-compunder or turbocharger wear, plus detonation margins when using lower octane avgas.

Until we start installing turbo-compounders in RVs, I don't see any benefit to reduced power take-offs, and even then I don't see the safety trade-off as worth it. Does sound like a fun experiment though

Takeoff Procedures - KISS

Each to his own - but be sure to include all the parameters - especially operational (vice financial) in your reasoning.

RV-8A, IO-360, 180 HP. Operate out of Inyokern, CA, 2400' where temps are above 100 degrees F nearly every summer day. I do full power takeoffs, stick full aft, let it get airborne when it wants to. Lower the nose slightly to accelerate to 100 kts. and quickly climb at full power.

100 kts. gives me some airspeed margin - converted to time - for analysis during a potential "WTF was that?" low level event. 100 kts. and 800 ft AGL gives me the option to put it down without power, but with aggressive maneuvering with stall margin, on one of the three IYK runways - or do a controlled crash into the desert.

Note: this is not a reopening of the never-to-be-resolved turn back to the runway debate. The above has been practiced and works for me - your results may vary.

Reduced power take off

Gents,
I do this every day for a living. There are actualy two ways of doing it. The one is a fixed de-rate on the engines ,and the other more popular way is to use an assumed temperature method. The crux of the matter with reduced thrust take off is to assure the minimum climb gradient incase you have an engine failure at V1 (which single engine aircraft dont have) and then to make the second third and fourth climb gradient on the remaining engines. This is ONLY for multi engine aircraft that can performance comply .IT DOES NOT applay to single engine aircraft AT ALL.
Use all the "power" you have on a single to get you in the air and as high as possible in the shortest time
Redards
Arie
Boeing 777 Captain

wirejock said:

I'm no expert but I did drive race cars for a few years. Granted, they were very different from our Lycomings and driven very hard usually at redline as long as possible. Every failure I saw or experienced seemed happen coming off a high speed straight. Boom, oil all over the place. Never once saw a failure on hard a acceleration.

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I distinctly remember engine parts flying across my hood just as the guy in front of me let off to get on the binders. Lucky for me, none of his parts came through the windshield!

save yourself

Bob Collins and Arie put it best, in simplest terms.
Comparing the original question about RV piston engines and airliners...is way off track.
Get to an altitude where that single engine four banger can glide someplace survivable. Period.

My local airport is close to town and we try hard to keep the noise level down.
For me this means 2600 rpm until airborne, then 2500 for initial climb.
With a c/s prop this is not much of a power reduction, but does seem to reduce the noise. At least it isn't so annoying.

I'm still way above the climb gradient of any non RVs on the field.

Are 150 hp RVs unsafe because they don't climb quickly? They still climb much quicker than a C 172.

Safety is a relative concept, and we all accept higher degrees of risk than necessary for expediency. Do we all climb to 15,000 to cross 20 miles of water? Do you fly direct routes over the rocks or follow roads?
Being safety conscious doesn't mean accepting no risk

Engine failure on take off is probably not the greatest risk we face. You stand a chance of walking away from it.
It's mid air collision that keeps me awake at night.

Deakin/Braley

If I recall correctly from the GAMI seminar I attended last year, reducing MP lowers internal cylinder pressures (ICP) and correspondingly CHTs. However, contrary to my belief - and most others I suspect - reducing RPMs actually increases ICP, albeit only a small amount. The takeaway from the gurus was to climb at max power, max rpms, full rich with two exceptions: 1) if you want to lean in the climb (optional); or 2) if there are noise abatement considerations.

Plus, it's a lot more fun to let the horses run...

Jim, with all due respect, by reducing the rpm from 2600 to 2500 you are NOT doing a reduced thrust take off. By starting the take off run with less than all available power you are. You might not know ,but to do a reduced thrust take off in a jet liner and then comply with the climb gradient in case of an engine failure at V1 a C150 ,even on a hot day ,will out climb us, you will be lucky to see 2-300 feet per minute rate of climb. I will say it again, recuced thrust take offs are NOT for single engine aircraft. Save it for the airlines

N941WR said:

I distinctly remember engine parts flying across my hood just as the guy in front of me let off to get on the binders. Lucky for me, none of his parts came through the windshield!

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That's usually because you are at max rpm (max piston speed/acc.) and when you let off the go pedal there is no boom to help turn the piston around and the rod and wrist pin have to do it all. You also get some shock cooling of the valves and every now and again a head pops off. Not to mention torsional reversals in the crank. Sometimes it gets ugly.

Also don't forget how the cylinder walls and cam get lube, from the oil being thrown off the rod big ends. Idle bad, rpm good!

Reduced power

The industry standard for light aircraft, normally aspirated, with constant speed prop, is a power reduction to something around 24" /2400 rpm, at a safe altitude after takeoff. Turbocharged aircraft are similar but the power reduction would be from perhaps 38" mp to 32" mp, numbers vary depending on the engine.
Many have no limitation to prevent a full power climb, but it does use a lot of fuel, especially with turbocharging.

jrs14855 said:

The industry standard for light aircraft, normally aspirated, with constant speed prop, is a power reduction to something around 24" /2400 rpm, at a safe altitude after takeoff. Turbocharged aircraft are similar but the power reduction would be from perhaps 38" mp to 32" mp, numbers vary depending on the engine.
Many have no limitation to prevent a full power climb, but it does use a lot of fuel, especially with turbocharging.

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Once again what you describe is NOT a reduced thrust take off

Engine Failure on Takeoff

There are a lot of angles from which to view this. Here is mine.
Years ago, as a 727 Captain I was a Max Power guy. That was until I read that over 96% of all engine failures that occur on takeoff, occur when utilizing maximum power. The engines failed because they were being operated under maximum strain, at their limits. Seldom do engines fail when they are simply 'loping' along. And for those that do, they may well have been abused on a max power takeoff flights before. That realization gave me a way to reduce my chances of having an engine failure on takeoff to less than 4%. I liked those odds and it served me well thru the 757, MD11 and my C-180. I'll use it on my RV-8 too. Extended engine life and fuel savings are just side benefits from not abusing your engine with max power takeoffs (when not needed). Minimizing engine failure on takeoff is the prize.

Power

I did not say that it was, just pointing out that reduced power in the CLIMB is not likely to cause engine damage on small recips.
I absolutely believe that reduced power from start of takeoff run WILL cause damage on some small recips. The takeoff from standing start to climb airspeed is a very critical time, especially in high ambient temperatures, and reduced power causes additional prolonged stresses on the engine.
Small piston engines should be operated at full power for all takeoffs unless there are red line considerations such as on the turbocharged engines.

Arie, I beg to differ. At 2500rpm, you cannot develop full thrust.
The point I wanted to make is that many of us accept less than full thrust routinely for reduced noise.

The airline stuff is interesting but irrelevant. Good for another forum.
BTW in countless assumed temp takeoffs I rarely saw as low as 300fpm.
Plus there was always the option of a throttle push if you lost a fan.

@jdearborn, I was also a 727 captain, and now 777 captain, but I was never a max power guy. Reason is ,the planes we flew was so thoroughly tested and certified regarding the power available ,to what is needed to get the job done. Therefore a reduced thrust take off in a airliner is standard operating procedure. That is the reason the plane I fly now cost close to $300 000 000 a piece , but you could most properly build it for 10% of that if you take the cost of testing and certifying out of the price tag. To bring you back to your C-180 ,you would have a pilot operating manual ,with graphs showing you what your performance is going to be regarding weight, temperature, and altutude. But they all asume that you are going to push the throttle all the way into the instument panel on take off. How do you decide that today I am only going to use what ever manifold pressure on this take off instead of going with that the manual says.

Jim you are correct, it is not RV related. I apologize for the thread onto airline opperations. Sorry about that, now lets get back to the topic. The OP asked a question regarding using reduced thrust on take off. For me the take off phase start at the beginning of the runway up to the point where the wheels leave the ground. Once the wheels are of the ground you are in the climb phase. What ever you decide to do in the climb phase regarding your thrust setting has got nothing to do with the take off.
Regards
Arie

My 2 cents:

Airlines began using reduced power or flex power takeoffs for two reasons: Extending the time between engine overhauls and for good neighbor noise abatement departure procedures.

Of the many engine operating parameters that are monitored, the "hot section" of the engine takes the most abuse. By taking off at a reduced power setting the turbine section is exposed to lower peak operating temperatures, thus the turbine blades, metallurgically speaking, are subject to less stress (fatigue cracks and turbine blade creep). From an economic standpoint, the airline will gain about 20% more operating cycles out of that engine before that hot section would require overhaul.

Wrt my single engine airfliver...always full power takeoffs.

Reduced Power Take Offs?

Hmmm...
The current Cessna 172R uses a Lycoming IO-360 engine rated at 160 hp. The engine has been derated from its usual 180 hp rating. Does this mean that EVERY Cessna 172R is doing a reduced power take off? Or that the Robinson helicopters that derate their engines are doing the same?

Hi Arie. When I started airline flying the 727 was still in production, Reduced Power takeoffs were just being developed and the old timers weren't really buying in to it. We had to be convinced it was a good thing and I was convinced. I liked going from the 96+% to the 4-% probability of an engine failure on takeoff.
Judging from the fact you are still flying the 777 you entered the airlines at a time when Reduced Power takeoffs were the norm. Regardless, I think we are both on the same side of the issue and I'm not sure why you are taking exception to my supporting Reduced Power takeoffs.
The C-180A POH does not address required takeoff power settings. It does address limitations and performance parameters. Density altitude, weight and runway length allowing, I use climb power as my takeoff power. It is supposed to: "work good and last a long time" . . . and keeps me in the less than 4% area.
For those who want to claim I'm 'just an airline pilot'. . . I learned to fly in a J-3 over fifty years ago and I have over 20,000 hours. I have flown most of the Piper and Cessna singles and the Beech twins. I've flown round engine ag stuff and T-28s. I flown military fighters and I have a Vietnam combat tour in the OV-10A and the YOV-10D. I'm not glider or seaplane qualified. That doesn't make me 'know it all' or right, but it does give me a considered and qualified opinion.
Cheers!