Why do we startup and shutdown piston airplane engines the way we do?

redtail said:
This is the one that makes the most sense to me. After all, why do we even have to still be bothered with priming or the mixture? Seems like with modern technology, mixture would be automatically adjusted for the current conditions,
i.e. density altitude:dunno:
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Fly a Jabiru Light Sport. They use a Bing altitude-compensating carburetor popular on some motorcycles. No mixture control...start and stop with the ignition switch.
 
Silvaire said:
That's what we called an "automatic" choke. I'm old enough to remember having to pull a knob on the dashboard and then push it back in when you got it warmed up a bit.
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Heck, I still have manual chokes on garden tools like my weed wacker and blower. :D
 
Silvaire said:
That's what we called an "automatic" choke. I'm old enough to remember having to pull a knob on the dashboard and then push it back in when you got it warmed up a bit.
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there are still some little 2 cycle motors you need to do that . . . . its amusing to watch the youngin's trying to start these little motors and not use the choke . . .
 
comanchepilot said:
there are still some little 2 cycle motors you need to do that . . . . its amusing to watch the youngin's trying to start these little motors and not use the choke . . .
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My last bike was a 2005 Kawasaki EX500 that worked this way. It seems to still be pretty common technology on motorcycles.
 
Ghery said:
Yes, I'm old enough to have driven such dinosaurs.
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Ghery, I bet you remember manual chokes, too! Welcome to the club.

I learned about shifting a manual and double clutching the straight crash box on a 1934 Ford Fire Truck at the summer camp where I worked as a kid. God I'm old.... :yikes:

-Skip
 
Ghery said:
Stepping on the gas pedal also set the choke if the engine was cold. Yes, I'm old enough to have driven such dinosaurs.
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My first car had a hand crank as a backup to the starter. Really. (and a manual choke) 1959 Sunbeam Apine.

After doing emissions calibration on cars with carburetors the habit of setting the choke was so ingrained that I would catch myself doing it in fuel injected cars for years and years after.
 
MassPilot said:
My last bike was a 2005 Kawasaki EX500 that worked this way. It seems to still be pretty common technology on motorcycles.
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Kawi hasn't changed a profitable formula in years...and they won't until forced by the market.
 
MassPilot said:
My last bike was a 2005 Kawasaki EX500 that worked this way. It seems to still be pretty common technology on motorcycles.
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Not eactly... that lever on your left handlebar opened a fuel enrichment circuit in the carb, not a choke.
 
Jaybird180 said:
Kawi hasn't changed a profitable formula in years...and they won't until forced by the market.
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Kawasaki stopped selling the carb'ed EX500 in 2009, it was replaced by the fuel injected 650r.
 
And don't forget the old British twins, with Amal concentric carburetors, as well as my Puch-manufactured Sears Allstate motor scooter, which used "ticklers" to enrich the fuel/air mixture for first start.
 
Why is it proper to shutdown the engine by pulling the mixture and starving it of fuel, rather than shutting off the ignition like every other vehicle I've ever operated?
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Well, I don't see where anyone else has said it so I guess I will...

...anyone who has over a dozen or so hours of training and who doesn't know the answer to this question should beat the **** out of their CFI. There is no excuse for not being taught this early in training as it is a huge safety item.

OTOH...you might have been taught but subsequently forgot...we all forget things...especially as we get...uhhhhhh...older. :wink2:
 
timwinters said:
Well, I don't see where anyone else has said it so I guess I will...

...anyone who has over a dozen or so hours of training and who doesn't know the answer to this question should beat the **** out of their CFI. There is no excuse for not being taught this early in training as it is a huge safety item.

OTOH...you might have been taught but subsequently forgot...we all forget things...especially as we get...uhhhhhh...older. :wink2:
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I was taught to always shutdown with the mixture and never with the key. I was just not taught the reasons why. I assumed it was more of a wear and tear thing than a safety issue, but either way my CFI made it clear not to shutdown with the key. I know I didn't just forget, and I actually have a lot of respect for my CFI, even if he didn't explain the exact reason for every little thing we did.
 
MassPilot said:
I was taught to always shutdown with the mixture and never with the key. I was just not taught the reasons why. I assumed it was more of a wear and tear thing than a safety issue, but either way my CFI made it clear not to shutdown with the key. I know I didn't just forget, and I actually have a lot of respect for my CFI, even if he didn't explain the exact reason for every little thing we did.
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A good, in-depth ground school should cover the detailed operation of our engines and explain why we do it this way - but I have learned that a surprising percentage of our flying pilots today did NOT receive a decent ground-school in their initial training.
 
MassPilot said:
I was taught to always shutdown with the mixture and never with the key. I was just not taught the reasons why.
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You should always be taught the reason why...for everything...but especially on important safety items like this one.

[sarcasm]Go beat the **** out of him before he kills someone![/sarcasm]
 
MassPilot said:
I was taught to always shutdown with the mixture and never with the key. I was just not taught the reasons why. I assumed it was more of a wear and tear thing than a safety issue, but either way my CFI made it clear not to shutdown with the key. I know I didn't just forget, and I actually have a lot of respect for my CFI, even if he didn't explain the exact reason for every little thing we did.
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I'm sure you do have a lot of respect for him, you trust him with your life. Unfortunately many CFIs lack the competence they should have and primary students lack sufficient reference with which to judge said competence.

Not a knock on your CFI, just a fact. We've ALL been there. Some keep going back for more.:confused:
 
And you can tell by the number of contradictory "I was taught" comments that it doesn't really matter whether the information came from a ground school or other source, much of the information is simply incorrect.

In fairness, some of the stuff (like LOP) is somewhat new and/or has been hotly debated for years. It's unrealistic to think that unanimity of opinion would be present regarding those subjects.


airguy said:
A good, in-depth ground school should cover the detailed operation of our engines and explain why we do it this way - but I have learned that a surprising percentage of our flying pilots today did NOT receive a decent ground-school in their initial training.
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airguy said:
A good, in-depth ground school should cover the detailed operation of our engines and explain why we do it this way - but I have learned that a surprising percentage of our flying pilots today did NOT receive a decent ground-school in their initial training.
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When I learned to fly, most of us kids grew up fooling with mechanical things like lawn mowers and chainsaws and go-karts and motorbikes. Fixed them all, or at least took them apart and gained understanding. Kids now grow up fooling with Game Boys and seldom go outside and play in the yard or street and are totally ignorant of anything mechanical. They learn to fly, and become instructors and, without the frame of reference we had, have no interest in why (or in learning why) we shut down using mixture or why carbs ice up or how leaning the engine affects it, among many other things. They drive cars that require nothing more than turning a key, pushing a pedal or two, and aiming it with the steering wheel. A computer does all the thinking for them, and they want airplanes to do the same. Someday they will, but in between now and then people will die because they aren't taught the whats and whys.

Dan
 
JHW said:
If you are old enough to remember carbeurated cars, you should recall pumping the accelerator pedal before a cold start. That was to pump some fuel inth the intaka manifold with the accelerator pump. Just like in your cessna.
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And to set the automatic choke to a rich position (as determined by the engine's current ambient temperature.)

-Skip
 
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