Constant-speed Pitch Propeller - Cessna 177RG

[fpico]

Hi Everyone, I would like to share my experience flying a constant speed propeller Cessna 177RG:

 

For the complex endorsement, I have started with a 1975 Cessna Cardinal 177RG (C177RG), apart from being considered a complex airplane, it also has additional horsepower and some extra weight. I am writing the following as the highlights from fight instructor classes I have undertaken, and especially a lot of pattern circuit work (touch & goes) to perfect landing the Cardinal, including many crosswind landings.

 

Constant-speed pitch propeller (aka. variable pitch propeller)

 

The first thing you notice is that the there are three knobs, usually : throttle (black lever), propeller (blue knob) or mixture (red knob), the blue knob is sometime is black, but positioned in the centre between the throttle lever and mixture knobs. Both the propeller and mixture knobs are turning knobs for precision.

 

Note:

 

• Throttle (black lever) - for manifold pressure (MP)
   
  
• Propeller (blue knob) - for RPM
   
  
• Mixture (red knob) - for fuel mixture
   
  

 

 

 

For take off the throttle and propeller knobs should be in the full forward position, and the mixture should also be in full forward position or set for best power (consult POH).

 

During taxi, use the throttle lever (black) as in a fixed pitch propeller plane, and keep the propeller and mixture knobs in the full forward position. This is also the recommended configuration for takeoff, approach and landing.

 

During flight (cruise), RPM and MP should be set as required, and any major changes for climbing or descending should be handled as follows:

 

Increase power (climbing):

 

First, the propeller knob to raise the RPM

 

Second, the throttle lever to raise the MP

 

Reduce power (descending):

 

First, the throttle lever to decrease the MP

 

Second, the propeller knob to decrease the RPM

 

Note:

 

I would recommend not touching the throttle (black lever knob), propeller (blue knob) or mixture (red knob) until you are at safe altitude after takeoff.

 

Starting the Engine

 

When starting the engine, I have not yet experienced any issues with a cold engine start. First, I prime the engine with the fuel pump. I begin with the master on and throttle in 1/4 inch (1/2 if flooded), propeller set to high RPM (pushed inward), fuel pump on and mixture full rich. The fuel flow gauge should show up to 4 - 6 gallons per hour (GPH) in roughly 6 seconds. Fuel pump off and cut-off the mixture. The engine is now primed, the above should be omitted if the engine is warm.

 

Turn the key in the starter to crank the engine, and as soon as the engine fires, slowly move the mixture to full rich and adjust the throttle to 1000 RPM, and check oil pressure in green within 30 seconds.

 

TIP: Don’t crank the engine for more than 10 seconds, as the starter heats up and needs to rest before trying again. Each time the engine is cranked; the engine requires more fuel, and the engine may need to be primed again using the fuel pump, always confirming their is sufficient pressure on the fuel flow gauge.

 

Circuit & Landing

 

Every plane is different, and there is no exception with the Cardinal, the landings are handled differently to its little brother the Cessna 172. The circuit speed also needs to be considered, as the extra horsepower really gets you moving on the downwind leg.

 

I find it important to start controlling the speed as soon as you turn into downwind (after climbing), moving the throttle (black) lever back until the manifold pressure (MP) reads 21 and slowly rotating the propeller (blue) knob back to 2,300 revolutions per minute (RPM), aiming at 115 MPH, and trimming to 95 MPH at about halfway along the downwind leg seems to work fine for me.

 

Once in beam with the runway numbers, I start to prepare and configure the plane for landing. First, landing light on, put in 10 degrees of flaps, and move the engine controls to full rich and full RPM. I continue by lowering the landing gear at no higher than 95 MPH. With the confirmation of the green landing gear light I know I am right to go. As the speed stabilizes, I start to turn and descend on base and trim to 80 MPH. On turning on final, I double-check the landing configuration, the landing light, landing gear, flaps, full rich, and full RPM (and landing gear again).

 

Landing

 

On landing I find the Cardinal fun, as it is different to both the Piper Warrior and Cessna 172, apart from the retractable landing gear, it is more sensitive on the controls (I assume because of the its huge stabilator).

 

Once on final, I aim at 80 MPH, and basically glide the Cardinal to the runway, maintaining the correct height from the ground, I may need to throttle a little on a windy day, and never allow the speed to get below 80 MPH.

 

Once over the runway, I hold its position and allow the plane to settle on the runway, if I balloon during the flare I never push forward on the controls, I just hold it and allow the plane to land. If needed I give a little back pressure on the controls. In case of ballooning too high, and the rate of decent continues to be high, I throttle a little to cushion the landing.Once on the runway, avoid being aggressive on the brakes, avoid them and allow the Cardinal to slow down before using the brakes.

 

That’s it.

 

TIP: The doors on the Cardinal are huge, so it is important to keep this in mind on windy days. Be very careful opening the doors as they do not have struts to limit their forward opening motion, and the force generated by wind can certainly damage the door hinges. It is important to avoid any unnecessary repairs.

 

https://www.funflyingwithfrank.com/post/my-cessna-177-rg-cardinal-experience

 

Cheers,

 

 

 

[rgmwa]

Interesting. I've never flown a constant speed prop or retractable gear aircraft, and probably never will, but at least this description gives me an idea of how to do it. Might come in handy one day.

 

 

[djpacro]

For info, I note that many put stuff like this in checklists: "check oil pressure in green within 30 seconds". Lycoming actually states: "If minimum oil pressure is not indicated within thirty seconds, stop engine ...". Short story is that it does not have to be within "the green". Quite a few variables such as different installations in different aeroplanes (my aerobatic aircraft have lots of extra oil hoses for the pump to work against when cold especially), ambient temperature and type/grade of oil.

 

 

[Yenn]

You missed one thing. Don't increase manifold pressure, ie open throttle, without increasing fuel flow with mixture. You could go from low rpm and medium throttle with leaned mixture and working well, to full throttle and low rpm and a risk of detonation. You may not have that problem, because in my experience very few instructors use mixture or teach about it.

 

 

[fpico]

You missed one thing. Don't increase manifold pressure, ie open throttle, without increasing fuel flow with mixture. You could go from low rpm and medium throttle with leaned mixture and working well, to full throttle and low rpm and a risk of detonation. You may not have that problem, because in my experience very few instructors use mixture or teach about it.

 

thanks for tip, I will look into it.

 

Cheers,

 

 

[facthunter]

 The general rule is don't lean above 75% power. It helps to have an accurate flowmeter which gives you a good cross reference that all is well with the engine. Nev

 

 

[w3stie]

Thanks for the info. That's a sleek looking aeroplane ?

 

 

[facthunter]

 With a CS prop, engine revs are managed by a governor.(once it's off the stops) and it will stay at the same revs when the engine has a fault, so the usual rev drop like for a full power check on take off,  won't show. . Over about 5,000 ft  you can have full throttle and lean it as the MP has fallen so your max power is  at or below 75%. . Nev

 

 

[fpico]

Hi all,

 

Thanks for the feedback, something that I don't mention is the COWL FLAP, any suggestion on best practices.

 

Thanks again.

 

 

[fpico]

You missed one thing. Don't increase manifold pressure, ie open throttle, without increasing fuel flow with mixture. You could go from low rpm and medium throttle with leaned mixture and working well, to full throttle and low rpm and a risk of detonation. You may not have that problem, because in my experience very few instructors use mixture or teach about it.

 

But I don't get it. Could you give more detail. thanks.

 

 

[Flyingfish]

You seem like a serious student. I would highly recommend a book called 'Mike Busch on Engines' by Mike Busch (available on Kindle). Or you could also learn a lot from his recorded webinars available on YouTube - search for 'Leaning basics' then 'Leaning: the advanced class'. I found all these resources fascinating when going from flying Jabiru and Rotax with fixed pitch prop, to a Lycoming IO-360 with constant speed prop.

 

Here is an article that discusses leaning, power changes and detonation.

 

https://www.savvyanalysis.com/articles/controlling-the-combustion-event

 

 

[facthunter]

The CS prop is like a variable gearbox where you can under rev it if you choose to which is like being in too high a gear. That can give the engine a hard time and stop it giving full power  when you need it. You can also over rev it compared to best RPM for cruise if you just  leave it in fine (selected ) as you increase speed, Fine Pitch is used for take off , taxi and all ground work, and is often/usually selected Later on approach to "ready" the engine for any go around.

 

      Mixture is another matter that doesn't just relate to CS (or in flight, variable pitch props which don't have a "governed" (that you change) speed but you directly vary the BLADE's angle mechanically..) High power and "loading" an engine (making it PULL harder at lower revs) need rich(er) mixtures and as a general rule don't lean when you are using over 75% power.. RPM and manifold pressures relationships are dealt with in the aircrafts POH and there are a few combinations possible but just generally don't have too high MP 's with LOW engine RPMs...

 

        Cowls are used in cruise and descent to stop the engine becoming too cold or when you feather an engine in multi engined planes to reduce drag. Some DC-3's didn't even have them  but all planes could benefit from having them as YOU can control the engines cooling air more precisely and reduce drag  at the same time. Nev

 

 

[skippydiesel]

Back in my GA days I enjoyed my experience in the 172 CS RG  - it had just the right amount of extra performance & complexity to make me feel I was really moving up in the aviation experience/skillset.

 

 

[Yenn]

Another tip is to use the mixture control on thee ground. After startup lean well back so that the engine runs but will not take more throttle without dieing. This will reduce the liability of oiling the plugs. You must lean well back so that if you try to take off leaned it just dies on you. If you only lean a little, you can get to take off speed and then have it die on you. Not fun. Also lean during taxi back after a flight, for the same reason.

 

 

[Jase T]

I did my CPL in a 177RG (CVG) in the 90’s. Loved it but the luggage door was an issue as it wouldn’t necessarily always stay closed... Oh and I had an LGE again I extend on my CPL test! Only thing I will add to your very accurate constant speed lesson here is this. ALWAYS read your aircraft flight manual! Some will allow an ‘overboost’ it varies with type. And whilst Pitch up Throttle up is always a good idea it may vary.