Less than full power takeoffs?
 

Don't think this has been brought up for discussion so am interested in other opinions.

We are taught and conditioned into full power takeoffs.

On a long runway I tried an experiment with a seneca five twin and applied the climb setting rather than the takeoff setting. Ok I had a massive runway but the takeoff was smoother and quieter for the PAX, the aircraft took off and there were no power changes and straight into a a climb setting.

Ok this was In a twin and I realise the takeoff distance would not match the manual, engine failure? Just shove the levers to MAX but the whole thing was silky smooth for the PAX.

Have others tried less than max takeoffs on long runways ?
Larger aircraft do this so I was just experimenting :ok:
it will reduce the strain on the engine but only on long runways

I have done less than full power takeoffs many times, for varying reasons. In my flying boat I found to my surprise, that with some careful handling, I can takeoff, fly, slow to descend from within ground effect (water really), land, and takeoff again, all at 19" MP, without touching the power. Doing that is just a skills thing. Other takeoffs are partial power just to be nice to neighbors, particularly on lakes, both wet and frozen. Flying single pilot turbine, I have done partial power takeoffs to prevent having to very carefully set power during the roll in a tight runway. There's always more power if I push the power lever, so if partial power is trouble and worry free for over temp/torque, so much the better. Better eyes out on the road! Last, and fearsome, there are some higher performance single taildraggers, which are going left off the runway, if you open up the power at an airspeed below that in which the rudder has effect. Partial power until the rudder rudders!

If I have a long runway and nobody else is around, I put partial power in on the Maule lift the tail and go down the runway going faster then slower practicing balancing on the mains then full power 500 feet from the end. It's a lot of fun.

The original poster is asking about a Seneca 5, so the first question has to be ..."is this a Public Transport Flight?"

Assuming it is PT then you need to ask yourself...
Is it permitted in your Ops Manual? Probably not mentioned at all.
Where would you get the Take off and Climb Performance figures from?
Would the CAA be happy with the extended exposure at low level?
Would they be happy with... "engine failure? Just shove the levers to MAX"... after an engine failure?!

So, off the top of my head, I'm sure its a non starter for Commercial Ops.

For Private Flights ...well I don't know! What does your Flight Manual say?

Folks, Australia's CASA published an article on same some years ago (10+). Quite conclusive that it is NOT a good idea for many reasons. Google it.

Good point, I had a look...

One of the types I was referring to says:

"Gradually advance power lever, keeping the stick fully rearward until required RPM is achieved........ Normal takeoff may be accomplished at a lower power than the maximum allowed"

The Caravan says:

"Power - SET FOR TAKEOFF (observe Takeoff ITT and Ng limits). Refer to Section 5 for takeoff power". The Section 5 "ENGINE TORQUE FOR TAKEOFF" table states 1900 RPM, and provides a table "area" which includes a large range of power within torque and temp limits.

A few piston types I know (C 182, for example) are RPM limited for noise abatement by STC, so they are not developing full power at takeoff, using the Flight Manual procedure.

Others I checked do say "Full throttle" for takeoff.

Every single engine piston POH that I have specify "full throttle" for takeoff and for those with constant speed props, the max RPM.

A reduced power takeoff is therefore not an authorized procedure.

Personally I think it is a bad idea in a SEP because in the event of an engine failure. altitude = options. So a reduced power takeoff means that you will not be as high as you could have been at every point in the take off flight profile.

I think it should also be noted that virtually every carburated and fuel injected piston engine is designed so that it has an extra rich mixture at full throttle. Therefore the engine could will run hotter at a high but not full throttle setting. This is particularly significant with turbocharged engines

I echo big pistons forever, esp about cooling with extra rich mixture.


BUT for the Seneca V driver. How about this: you do a reduced power takeoff (climb power) and you lose an engine.

Do you add power on the good engine?

I'll bet you would have to. BUT IF YOU WERE ALREADY at full takeoff power, you would simply have to feather the bad engine, instead of moving throttles around.

Actually, no, not quite. I fly the GA8 with an IO-540. Takeoffs are done using 2500 rpm. In fact, 2500 rpm is the limit for all operations, except emergency. There is a detent in the blue lever that lets you get past 2500 rpm, but that travel range is marked for emergency purposes only.

2700 rpm gives about 30 more HP, but also considerably more noise. And that last thing is the reason for all this: All performance figures, including the noise measurements/certification, are based on 2500 rpm. With 2700 rpm allowed under all circumstances we would not be able to get the advantageous noise certificate we have now. Which significantly increases landing fees at some airfields.

But again, this is an exception. I do not know any other aircraft that has a reduced power setting as default in its POH.

The seneca Five is unusual compared to the Earlier Senecas in that the engines are turbocharged supercooled and waste gated and can use maximum continuos power.

the earlier Senecas were not and max power was time limited to five minutes
Let me put this question? After take off and having cleaned up the aircraft you would normally go to a climb power setting anyway so what happens if you loose an engine then? You would advance on the good engine or maybe on both until you had identified the problem engine and if you still had power from it, that procedure takes a fraction of a second.

In my engine failure in a twin (reported here) which happened at 200 feet agl do not be too hasty in shutting down and feathering what maybe an engine still supplying some useable power.

i estimated 30% from a violently shaking and yawing aircraft so instead put my hand on the prop lever ready to feather and used that 30% until a safe height then shut it down. Had I shut down and feathered I would have without doubt ended up crashing.

I think its the Aerostar( Machen) where engine failure requires a reduction of power on the good engine because the rudder could not hold full power and many engine failures resulted in loss of control.

Some powerful single turbines and pistons required reduced power because of torque and lack of rudder authority at slower speeds in the takeoff roll with further power added at faster speeds and more rudder authority ?

I opened this thread up not to promote less than full power takeoffs but to discuss them and less than full power operations when full power maybe your instincts

The only time I've used less than full power was while taking part in some advanced training (Mooney pilots proficiency program)and the instructor decided that the conditions which happened to present to us (wasn't planned) would be a good demonstration of hot and high at mtow.
We knew we would get off the ground safely and with room to spare but it was a very good demo of just how much extra tarmac was required and the very leisurely climb rate.

Where is Adam Frisch's opinion? He used to fly the Aero and can shed some light on this from his experience.

Desert D

Not sure whether it was all AeroStars or just the more powerful Machen conversion? But I am pretty sure all of them were a handful engine out and required a reduction on the good engine? i have never flown one of those quick birds ;)

I have quite a lot time in the Aerostar 601P, the single engine handling was interesting but not as bad as rumours state.
Of course in any multi engine aircraft you always have the option to reduce power on the operating engines to maintain directional control even if that means landing ahead under control.

Anyway as the OP said let's discuss the reduced power take-off.

Your first action during such a failure should be to confirm or apply full power to all engines anyway.

We never do full power takeoffs even at max weight. A light weight take off is 45-50% and a max weight will be 55%.

In the event of an engine failure we also do not go to full power on the live engine, its 'power as required' and in a light load aircraft we generally don't need to add any. Fully loaded we might add 5%.

I have found these articles excellent background reading

Pelican's Perch #63:<br>Where Should I Run My Engine? (Part 1) - AVweb Features Article

In turbines, reduced power takeoffs are the norm of course but, piston engines may not respond so well. In my experience operating old supercharged radials, it was recommended particularly to use full power for takeoff as the extra fuel provided significant cooling to the engine. I'm definitely no mechanical expert and read as much as I can to try and find the best operating methods for safety and engine longevity, but found this series of articles very plausible.

I have 500 + Aerostar hours. All Aerostars, including the Machen ones have a certified published VMC speed. This speed is below blueline for all models at all weights. If you are in any twin and flying below VMC you are going to have to reduce power on the operating engine.

If you are in this situation in an Aerostar anywhere close to the ground you are going to crash as this airplane will go nowhere but down at any speed below the (very high) blueline speed

Interesting, I just checked a 1967 POH for a 172 - full-throttle is only set to check at run-up, not written down for take-off. Only for max. climb rate full throttle is required. Any idea why Cessna decided to not document throttle setting for take-off, freedom of choice?

No idea, I have always used full power.
There is nothing more useless than the runway behind you.

If we take that the performance data is established from max power ( Not on all types of singles) then going away from that and using less than max power and the takeoff roll and initial climb will be degraded to an unknown factor.

Some high powered singles with a lot of prop torque effect require a lower power setting for the initial take off increasing that power as more air flows over the rudder.

That then beggars the question on lower powered singles do you stand on the brakes releasing them on achieving max power or smoothly increase to max power as speed increases. One is smooth the other much more frenetic for your passenger

Do you stand on the brakes regardless of whether the runway is short or long.

Sometimes in the past there has been an aircraft on finals! ATC ask you to expedite your departure as you enter the runway from the taxiway! Do you taxi out stop and line up on the numbers, hit the brakes and build to max power or start your takeoff slowly increasing power while in a turn to the centreline? :E to assist separation to the landing aircraft?

i have seen that done by more experienced pilots many times in large jet aircraft as well as small aircraft too! To be shunned on ? accelerating on the turn to the centreline? i.e. do you ever start your takeoff roll while entering the runway from the taxiway? Not advisable with max power so theoretically a reduced power takeoff