From time to time, I hear flight training overhead... From time to time, I hear an airplane throttled well back, fair enough, it's flight training. From time to time, a rather quiet airplane emits a sound very much like the pilot just jammed the throttle hard forward.

Steady on pilots! Go easy! Just squeeze the power in smoothly! Let the back cylinders catch up to the front cylinders, and not strain the crankshaft so much! Run it as though you'd like it to be reliable, even if you don't own it! Run it as you would like the pilots before you to have run it! Take the extra couple of seconds from idle to full power, it'll make you look like the smooth pilot you would like to be seen to be.

The Chief pilot you might be doing a ride with one day for a job, will judge you for this, why not practice being a smooth pilot now!

Rant over for now...

Why would the back cylinders have to catch up? Aren't most engines designed to have a somewhat equal length of ducting for air and fuel to get to the cylinders?

You wouldn't enjoy listening to the military twin otters, in the circuit, in the winter.

Took me about 10 lessons but I finally got that beat out of one of mine. Joys of taking over for someone else.

Why would the back cylinders have to catch up? Aren't most engines designed to have a somewhat equal length of ducting for air and fuel to get to the cylinders?

Yes, though I could thread drift that topic too! Catch up in the torque sense, all the power goes out the front of the engine.

The pilot jams the throttle forward, and the engine speed about doubles in seconds. The prop governor has to catch up, the vacuum pump and alternator speeds are suddenly doubled, counterweights jump around to find a new balance position, and there is generally strain on everything, which is not necessary. And, were there to be paying passengers in the back, they would not be impressed!

From time to time during testing, I do have to jam a control - it's part of the test... I cringe doing it! I sat lined up in the diesel Beaver last week, and, as an element of directional control on takeoff test, just jammed the power lever up to full. I was delighted to notice that the FADEC disallowed that, and increased the engine power smoothly, at a reasonable rate!

I flew three [new to me] big singles in the last month. Two pilots commented that I flew very smoothly, and the third owner thanked me for treating his airplane gently. Owners will notice how you handle their expensive airplane. In most cases they've had to pay to fix something a pilot has broken before. You're doing yourself a favour as a new pilot, if you make gentle airplane handling a priority early in your training, so you don't have to learn that as a new skill later to get that flying job you want!

Doesn't that mean that the back would accelerate 'first'? Prop is attached to the front, back has slightly less resistance, which means it will help the front cylinders to speed up?


To be clear, I agree with being smooth. I am just trying to understand the catch up remark.

Completely agree PilotDAR.

Always used the phrase "If you're doing something fast, you're doing something wrong" with students. Nothing in an airplane requires a fast response. Prompt absolutely.

Fast implies harsh and immediate with little to no thought, while prompt is quickly but smoothly and governed by knowledge and understanding of the situation.

"Slow is smooth, and smooth is fast"...

Fast implies harsh and immediate with little to no thought, while prompt is quickly but smoothly and governed by knowledge and understanding of the situation.

Yes, hopefully, your mind is ahead of the airplane, and you know what it's going to need next, so you can anticipate and ease it in, rather than a last minute jam.

Doesn't that mean that the back would accelerate 'first'? Prop is attached to the front, back has slightly less resistance, which means it will help the front cylinders to speed up?

Four cylinder engines less, but when you think about that long crankshaft, and applying the same amount of sudden power into each cylinder, the power from the front cylinders is absorbed by the propeller directly. The power from the rear cylinders is absorbed first by the whole length of the crankshaft, then by the propeller. Yes, I know that crankshafts are designed to absorb the power, but crankshafts have also broken. And as you [hopefully not] jam in the power, the plain bearings (and film of lubricating oil which protects them) of the crankshaft are taking the forces of high power, with the low oil pressure of what was idle moments earlier. A throttle opened smoothly allows the oil pressure to increase, the internal engine loads to be less severe, and better carried by the higher pressure oil, and the accessories to accelerate smoothly under their loads. The fact that an engine will take abuse does not mean that it should!

The real danger is stalling the engine if it's carbureted. They have accelerator pumps to prevent this but if that's not working properly the sudden influx of air will shut the engine right down if you push the throttle lever in too quickly. Happens to old VW's if you mash the gas pedal.

FL030 wrote: ↑Fri Apr 21, 2023 9:45 am The real danger is stalling the engine if it's carbureted. They have accelerator pumps to prevent this but if that's not working properly the sudden influx of air will shut the engine right down if you push the throttle lever in too quickly. Happens to old VW's if you mash the gas pedal.

That shouldn't be an issue in the air. The windmilling prop should restart the engine right away.

5x5 wrote: ↑Fri Apr 21, 2023 8:40 am Completely agree PilotDAR.

Always used the phrase "If you're doing something fast, you're doing something wrong" with students. Nothing in an airplane requires a fast response. Prompt absolutely.

Fast implies harsh and immediate with little to no thought, while prompt is quickly but smoothly and governed by knowledge and understanding of the situation.

Nothing? I get what you are saying, but what about a imminent mid air collision, or imminent ground contact.

Agree 100% on the smooth power application. So many reasons why to do it. Back in the day, when training in carbureted trainers such as 150’s, Cubs, etc., without accelerator pumps, a sudden jamb of the throttle could bring more excitement than desired. Particularly in overshoots, climb outs from simulated forced approaches, etc. a faltering engine and approaching terrain was never a calming mix. With high powered singles, a sudden surge of power at low speed, especially if during slightly uncoordinated flight, can produce enough torque roll and yaw to induce a spin. Another low level event that needs to be avoided. The list goes on…..

the sudden influx of air will shut the engine right down if you push the throttle lever in too quickly.

Yes, that's another good way to teach easy on the throttle! I had my lesson with that in a Cub on skis on the lake....

The windmilling prop should restart the engine right away.

No... I had to get out and hand prop it, appropriately memorable!

The carburated 172s and 152s I've flown all cough a bit when the throttle is jammed in. Luckily I've never had one quit. The grumman im flying tended not to cough at all so my student wasn't believing me when I kept telling him to apply power smoothly. Until it finally did. He's good now.

Many aircraft engines (including the ones in the 172) use carburetors with an accelerator pump that provides extra fuel when the throttle is opened rapidly to reduce the likelihood of the engine dying. You can see the piston pump at the back on the right in this picture:
https://msacarbs.com/wp-content/uploads ... 00x600.jpg

And in the front of this cutaway:
https://www.enginehistory.org/Accessori ... Fig046.jpg

It's the same piston pump that causes the engine to flood (and fuel to puddle under the nose) if you pump the throttle too many times before starting.

In very cold weather, the O-200 on the C150 will quit if you jamb the throttle in too fast, especially if you put the carb heat cold first. I always tell students to SLOWLY add throttle, then carb heat cold. I've had it happen twice on touch and go's. Embarrassing but I don't end up in the trees.

Same applies on TO. Treat em’ nicely.

Add power slowly, recheck oil pressure, then gradual full power and check temps and pressure again on the roll. Easy abort is things don’t look good, better to see it then than after liftoff.

Oh, and not a great idea to TO with CHT’s much below 300.

Temperature management is your friend.

Of course people treat airplanes so often like they treat everything else.

PilotDAR wrote: ↑Thu Apr 20, 2023 5:47 pm
The Chief pilot you might be doing a ride with one day for a job, will judge you for this, why not practice being a smooth pilot now!

Definitely can agree with that part. And it applies to the general handling of the aircraft altogether.