Proper climb procedures ?

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FlushDraw
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Proper climb procedures ?

Post by FlushDraw »

Hi, just wondering what are the proper climb procedures used for this aircraft ? What I am doing now is, flaps up / after take off reduce throttle to 23 in.hg manifold pressure and propeller set for 2400 RPM. This maybe correct according to the manual but I find it weird I am using less throttle during climb than I do in the cruse phase of flight. (Maybe that's how its supposed to work ?) Just wanting to fly this lovely aircraft as accurately to the real thing as possible.

Thanks,

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Nick - A2A
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Re: Proper climb procedures ?

Post by Nick - A2A »

Hi FlushDraw,

Your climb procedure sounds fine. What you're describing is the effect on engine power of cruising at altitude. Basically, the higher you climb, the thinner the air gets. Cruising up in that thinner air means that the mass of air the engine is able to suck in is significantly reduced. Because the engine requires both fuel and air to develop power, its power output is reduced proportionately.

This means you'll need to increase the throttle setting to maintain manifold pressure as you climb, exactly as you've noticed. (You'll also need to lean the fuel mixture a bit, to help match the thinner air.) Once you start cruising above about 6,000 feet, you won't actually be able to maintain that 23 in Hg manifold pressure at the top of the green arc, even at full throttle.

In other words, yes - that's how it's supposed to work (in the non-turbocharged C182T which A2A have modelled anway)! :wink:

Cheers,
Nick
A2A Simulations Inc.

FlushDraw
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Re: Proper climb procedures ?

Post by FlushDraw »

Hi Nick,

Awesome, thanks for the quick response. Makes sense the way you described it.

Mike

AusWilko
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Re: Proper climb procedures ?

Post by AusWilko »

Yes thanks, as a newb that also helped me as well as I was doing it but wondered if it was correct
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par2005
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Re: Proper climb procedures ?

Post by par2005 »

To my limited understanding, you use maximum operating power for the first 1000 ft (some pilots prefer lower), and then :

1) you throttle back to the top of the green on manifold pressure, which is 23 inch
2) you reduce mixture to achieve 15 gallons/h fuel flow rate

You maintain these two throughout the climb (you will have to increase manifold pressure as you climb due to pressure drop)
Propeller rpm stays maxed out, you pitch to maintain 85-95 kt.

This is the "standard" climb. Not the maximum rate, or maximum angle climb. For these you use maximum continuous power (check the placecard on the left of the panel, or the manual)

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AKar
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Re: Proper climb procedures ?

Post by AKar »

To add to the above, you don't have to reduce power after takeoff - the maximum rated power is also the maximum continuous here. Often if I know I don't level off until reaching cruise altitude of, say, 9000 ft, I don't reduce throttle except for the decent next time. If temps stay nice, I find little reason to pull out the throttle and almost immediately push it back in, and instead follow the max performance climb guidelines except of keeping higher airspeed than quoted for cooling if terrain is not a factor. There is not single absolute correct procedure but it depends. :)

-Esa

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Nick - A2A
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Re: Proper climb procedures ?

Post by Nick - A2A »

AKar wrote:Often if I know I don't level off until reaching cruise altitude of, say, 9000 ft, I don't reduce throttle except for the decent next time.
Yeah, maximum power climb is often quite tempting (in the sim anyway, where economy and noise aren't really an issue). No need to dawdle with normal en route climb procedure I guess, even if the MCP climb isn't, er, strictly necessary... :wink:

Cheers,
Nick
A2A Simulations Inc.

par2005
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Re: Proper climb procedures ?

Post by par2005 »

I see you guys are not hardcore enough :P

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AKar
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Re: Proper climb procedures ?

Post by AKar »

How's that? :) There are different ways of using the tools we've got here, some opt for margins given by book procedures while others seek to further optimize and extract from the performance we're given. That's what makes it interesting.

-Esa

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Nick - A2A
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Re: Proper climb procedures ?

Post by Nick - A2A »

I think Esa's pretty hardcore alright - you just have to read one of his 'technical' posts to see that! :mrgreen: In fact, this one (from the Cherokee forum): a nice cruise setting - using the altitude as your throttle, fits in very nicely with the OP's question in this thread. It's where I grasped the concept that it's that mass of air which the engine is able to suck in, which is really important here.

The linked post actually includes a graph of percentage of power (at full throttle) that the engine will develop, versus altitude. Well worth a look for Mike and any one else interested, though I guess it's taken from the PA-28-180C performance figures.

Cheers,
Nick
A2A Simulations Inc.

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AKar
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Re: Proper climb procedures ?

Post by AKar »

To add a few more quick comments, regarding noise reduction, it is often more useful to reduce the rpm a bit than to close the throttle. Though you'd want to avoid 'forcing' the engine to slow rpm while at high power setting. I'd advice to be cautious on using the rpm lever while at high power, especially if lacking any figures.

These kinds of engines are made to sustain prolonged operation at high power percentages - full power will be extracted for a good amount of time for every takeoff at least! When climbing with naturally aspirated engine, the available power decreases relatively quickly. Moreover, the quoted climb airspeeds are somewhat low, also for engine cooling. I tend to transform that extra power that full throttle gives me at low altitudes into forward airspeed, keeping up some 100 kias or maybe even a bit more, depending what can be achieved with reasonable climb rates. As engine power gets lower with increasing altitude, I slowly reduce the indicated airspeed closer to quoted best climb speeds to keep the VSI up - now the TAS is still very good due to a bit thinner air, that air is cooler and engine power is reduced enough so that I can keep it nice and cool. But it all depends on terrain, weight, the expected level-off altitude, the 'mission' and so on!

With engines, typically turbocharged, that quote maximum continuous power settings, the story would be different.

Also, I'd be reluctant to lean to any specific fuel flow figure, because that will result in different mixtures for different atmospheric conditions. This is because a gallon of fuel is way more closely of constant mass than a gallon of air is over different conditions.

-Esa

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DHenriques_
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Re: Proper climb procedures ?

Post by DHenriques_ »

par2005 wrote:To my limited understanding, you use maximum operating power for the first 1000 ft (some pilots prefer lower), and then :

1) you throttle back to the top of the green on manifold pressure, which is 23 inch
2) you reduce mixture to achieve 15 gallons/h fuel flow rate

You maintain these two throughout the climb (you will have to increase manifold pressure as you climb due to pressure drop)
Propeller rpm stays maxed out, you pitch to maintain 85-95 kt.

This is the "standard" climb. Not the maximum rate, or maximum angle climb. For these you use maximum continuous power (check the placecard on the left of the panel, or the manual)
Excluding density altitude of course, I've never been a huge fan of leaning mixture after takeoff. The engine is running pretty hot already and leaving the mixture rich helps the cooling. If doing an extended climb after takeoff, I monitor engine temps carefully and control them using cowl flaps if available and especially my climb angle and airspeed. I always lean for best power at altitude when climbing then monitor temps..........ALWAYS monitor temps, pressures, and flows. Engine management pays huge dividends when it comes to TBO.



Dudley Henriques

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Lewis - A2A
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Re: Proper climb procedures ?

Post by Lewis - A2A »

As a sim pilot I tend to do most of my fiddling once at cruise altitude, ill pull back a little during the climb but its not until at cruise that I'll start playing with getting some good mileage out of her.

thanks,
Lewis
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Zacke
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Re: Proper climb procedures ?

Post by Zacke »

Hey guys,

an older topic but I still have a question: In climb when reaching an altitude where you have to push the throttle full in for maintaining 23 MP isn't that the condition of maximum power and you should reduce fuel flow according to the "maximum power fuel flow chart"? In other word's: Doesn't a standard climb not always lead to maximum power conditions at critical altitude and you should lean the mixture?

Yesterday I climbed out to 12.000 ft with my Skylane and at about 7.000 ft I had the throttle full in with 23 MP and about 19 gph fuel flow. Should I have reduced it to 16 gph according to the MPFF chart?

Thanks in advance,
Zacke

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