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How hard is the C/S prop to fly??

tkatc

Well Known Member
Ok. Some of you may know that I am in the market for a 6A or 7A (Maybe even a 9A). I would like to build at some point but as of now I just want to buy a flying RV. I just completed my transition training with Jan Bussell in Florida and you guys were right. He is a great instructor. Patient, deliberate, calming. He put all my fears aside and while I don't profess to be an expert, I am confident I can fly an RV without bending it up.

While searching for the right plane for me I continually run into aircraft with a constant speed prop. I am trying to avoid a constant speed prop because it adds more complexity. Maybe because I have never flown one I don't know how simple it really is but I figure you guys could tell me what you think....is it that much harder?
 
Terry, a constant speed prop is the easiest thing you'll ever learn

...just don't overthink it. Everything is full forward for takeoff...prop, mixture and throttle. After you're established on your climb, dial the prop control back to around 2500RPM. Leave it there 'til you reach your altitude and throttle back to whatever manifold pressure you're going to run...usually around 23".

Either leave the prop where it is or dial it back to around 2400 or less....suit yourself...that's it. The rest of the flight is done with the throttle and only when you're on final for landing do you push the prop control forward...and that's not even necessary..you do that in case of a go-around, it'll allow the engine to go to redline...RV's will go around just fine with the prop at 2400.

BTW...congratulations on completing your training...

Best,
 
I had hardly ever flown a C/S prop before I finished my RV.

It's dead simple. There is no magic to it at all. Blue knob full forward for takeoff and landing. On take-off once upwind turn the blue knob back to 2500RPM. At cruise, turn it back to 2450/2400/2380 (those are my typical power settings according what I'm doing).

The great thing about a C/S prop is you can pitch the nose up and down and not worry about overspeeding the prop...unless you're Kevin Horton of course. ;)

Basic premise is...you dial in a desired RPM. If the engine has enough power to achieve that RPM, that is the RPM your prop will turn. The governor changes the blade pitch the achieve the constant RPM...and that's where the Constant Speed prop moniker comes from. Note that this is different from an in-flight adjustable pitch prop.
 
RE:Simple with great utility

As Pierre and Jamie said.

Like you I thought, Man this must be Complex, What to do, When to do it, ......

Get with a CFI and a Constant Speed Prop for a bit of training and you will soon be on your way.

Frank @ 1L8 ...RV7A... Flying and Tracken (MT-RTG)
 
I put a few hours in a 172XP, and had it all figured out in nothing flat. It's the simplest "complexity" you're likely to run across in the aviation world. See if you can find a friend or FBO to borrow/rent a plane with C/S prop and try it out with an instructor.
 
Throttle always to the firewall prop to desired RPM

It adds performance capability over the whole operating scenario. Operationally it is very natural. It should not be something that would direct you away from an otherwise acceptable airplane because of operational complexity. There is an annual lube requirement and a calendar and operational overhaul period so it is not the most simple, cheapest or maintenance free choice. If you are watching your bucks and can't or don't do your own maintenance maybe you want to keep looking for a good fixed pitch prop airplane. When you are ready to land throttle back push the prop to max rpm and fly it with the throttle like a fixed pitch prop.

Bob Axsom
 
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I AGREE with everything everyone has said thus far: I had ~2800 hours Total Time in my logbook, ALL fixed pitch, when I installed my constant speed prop. It took about 10 minutes instruction in the pattern with my friend Howard Long to learn how to use it properly :D Rosie
 
It took about 10 minutes instruction in the pattern with my friend Howard Long to learn how to use it properly :D Rosie

What took you so long Rosie...slow learner?:p

Like everyone else has said - it's hard to figure out why they call it "complex" - very easy to use.
 
A little different take

When I started looking to buy an RV, I wanted an "A" model and not C/S because I had no experience with either and relatively low time. Well, like you, the reality of the market caused me to reconsider on both fronts. (It was a seller's market five years ago with far less choices in my limited price range than right now!) So, I bought a taildragger with a C/S and did my transition training with effectively no experience in either.

Somehow, I found the C/S the issue that put stress over the top at first. I can't explain why since it is a dirt simple thing to learn and do, but it seemed like the thing that overwhelmed me the most. Of course, learning to land (and take-off) in a taildragger was really the challenge, followed by mastering the speed/power, but the C/S was the annoyance that drove me nuts. Once I got comfortable with the other issues, the C/S became a complete non-issue.

You seem to have an advantage of a little RV experience and you plan to stick with an "A" model, so I expect it will be absolutely no big deal at all.
 
...Maybe because I have never flown one I don't know how simple it really is but I figure you guys could tell me what you think....is it that much harder?

It's about as hard as setting the volume level on your home stereo.

I think where people get worked up is the old myth about running "oversquare" or the "order" required when adjusting the various knobs. But like most have said: takeoff and landing with the blue knob full foward; after that, simply dial in the RPM you want. It's easier than learning how to properly use the red knob - and you have that one down, right?

Go for it!
 
I'll add that, once you learn how it works, An RV with a CS prop is much easier to fly than one with a fixed-pitch prop.

Probably the most difficult thing to learn is that since full power is available from the beginning of the takeoff roll, so the takeoff evolves more quickly and you need a lot more right rudder from the start.

The potential for high sink rates when slow at idle power bears watching too.

The beauty of the CS prop, apart from the increased performance across the envelope, is the reduced workload in the pattern. In a FP RV, 10 extra knots means a very long landing or potentially a go-around.

With the CS prop, you can speed up or slow down pretty much at will. !0 extra knots? No problem, you can still plant it on brick one at any speed you want.

You can be sloppy with airspeed control and still look good.

Nearly all my time is in CS airplanes, or very draggy FP airplanes. The handful of FP RVs I have flown are high workload for me, especially in the pattern or formation.
 
Thanks for the input. I am getting more comfortable hearing your thoughts.

Flyeyes...or anybody else...please tell me about the power settings you use in the pattern. My transition training taught a very stable approach as follows....Climb out was 120 mph and full throttle. Downwind was whatever speed the airplane wanted to carry in level flight at 2100 rpm. At midfield downwind I was taught to reduce to idle while holding altitude, trim for slightly nose up, let the speed bleed off into flaps extended range, 10 degress flaps, drop to 85 mph and establish a postive rate of decent. The sink rate then becomes too high and you arrest that sink with a few hundred rpm. On the O-320 6A that came out to be 1100 rpm or so and I was all set up for 500-600 fpm sink. Holding 85 mph and a steady sink I would turn base and final adding more flaps on each. Throttle was sometimes required to arrest the sink. Eventually the throttle went to idle. I had to get used to the sight picture of putting the nose on the numbers and holding it. As I cam into ground effect I would arrest the sink rate with throttle or elevator as needed. Then looking out the side window I would have a much better view of how high I was and was able to grease at least 1 landing and was proud of most of the others which felt like very soft stable landings.

How would this all play out with a CS? I assume quite similar if you have the prop all the way in and just throttle for desired rpm. Or is there some magical play with prop angle to arrest sink rate or accel or lose speed?
 
...The beauty of the CS prop, apart from the increased performance across the envelope...
James, good post. I do have to quibble with this one statement. A fixed pitch prop can easily outperform a constant speed in certain aspects of performance. The constant speed excels in doing well over wide aspects of performance but not all of them. See Paul Lipp's (elippse) excellent post in another thread http://www.vansairforce.com/community/showthread.php?t=61183&page=2 A fixed pitch can be optimized to outperform a constant speed in specific areas.
 
James, good post. I do have to quibble with this one statement. A fixed pitch prop can easily outperform a constant speed in certain aspects of performance. The constant speed excels in doing well over wide aspects of performance but not all of them. See Paul Lipp's (elippse) excellent post in another thread http://www.vansairforce.com/community/showthread.php?t=61183&page=2 A fixed pitch can be optimized to outperform a constant speed in specific areas.


I agree absolutely. My point, although poorly stated, was that the CS prop is good across the entire speed envelope, rather than optimized for one part of it.

I readily accept that there are some excellent FP props, that are as fast or faster than my CS, but most of them are harder to slow down in the pattern. The same goes for climb props, although they will give up some cruise.
 
Thanks for the input. I am getting more comfortable hearing your thoughts.

Flyeyes...or anybody else...please tell me about the power settings you use in the pattern. My transition training taught a very stable approach as follows....Climb out was 120 mph and full throttle. Downwind was whatever speed the airplane wanted to carry in level flight at 2100 rpm. At midfield downwind I was taught to reduce to idle while holding altitude, trim for slightly nose up, let the speed bleed off into flaps extended range, 10 degress flaps, drop to 85 mph and establish a postive rate of decent. The sink rate then becomes too high and you arrest that sink with a few hundred rpm. On the O-320 6A that came out to be 1100 rpm or so and I was all set up for 500-600 fpm sink. Holding 85 mph and a steady sink I would turn base and final adding more flaps on each. Throttle was sometimes required to arrest the sink. Eventually the throttle went to idle. I had to get used to the sight picture of putting the nose on the numbers and holding it. As I cam into ground effect I would arrest the sink rate with throttle or elevator as needed. Then looking out the side window I would have a much better view of how high I was and was able to grease at least 1 landing and was proud of most of the others which felt like very soft stable landings.

How would this all play out with a CS? I assume quite similar if you have the prop all the way in and just throttle for desired rpm. Or is there some magical play with prop angle to arrest sink rate or accel or lose speed?


In general, you leave the prop control alone and make smaller and smoother throttle corrections with the CS prop than with the FP.

For me, I leave the prop set for cruise (usually around 2300 RPM) as I enter the pattern, slowly reducing throttle into the high teens (manifold pressure) for around 135 KIAS on the 45. I continue to throttle back into the low teens over 10 seconds or so to slow down to or below flap speed abeam the numbers.

Once you get below a certain throttle setting (depending on speed) the RPM begins to decay as the prop hits the low pitch stop and the engine power isn't enough to maintain RPM. This is referred to as "below the governing range." The prop in this range is generating maximum drag, as the blades are turned pretty much sideways to the airstream. The airplane will descend or accelerate very quickly here.

While at or below the bottom of the governing range (usually on base) I slowly ease the prop control all the way forward to maximize available drag, and maximized available power if I need to go around.

A small amount of throttle will speed up the prop to the governed RPM, but more importantly, the blades will twist to keep the RPMs from increasing. This immediately reduces drag. You can control speed very precisely over a pretty significant range when slow without having to pitch the airplane up or down much. Small, smooth throttle changes are more important with a CS prop, because the airplane responds much more quickly to throttle movement.

You can pretty much point the airplane at the end of the runway and expect to get there, even if you start a little high or fast.

The CS prop lets you vary the amount of drag almost instantaneously, so throttle reductions in the flare need to be small and or slow, lest the ground jump up and smite you.

As soon as the mains touch (I usually aim for a tail-low wheel landing) any remaining throttle is pulled all the way off, and the airplane sits right down.

Power-Off approaches are much steeper that with a FP cruise prop, but still allow precise landings, like any draggy airplane. If you find you are too draggy and don't have power available (i.e. a dead stick landing) as long as the prop is windmilling and you have oil pressure you can pull the prop control back top reduce drag.

It's really easier than it sounds

this might give you a sense although you can't see the you can hear the power changes
 
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something else

to consider, the C/S prop while simple to use is more complex than a fixed pitch and also requires a governor as previously stated. The operation of these "systems" and their failure modes should be understood so that you will know how to recognize a failure and how to deal with it. Some examples may be, oil starting to spritz on the windshield (prop seals failing) or, rpm over-speed (governor failing) come to mind. The latter would seem to be instantly critical. What would YOU do to maintain control of the aircraft? :)

Bevan
 
C/S prop pattern procedures

I must agree with the majority: the constant speed adds SYSTEMS complexity, but PROCEDURAL simplicity.

I prefer to enter the pattern from an overhead approach. (OK, call it UPWIND leg for any of you who say that an overhead approach is not a recognized term for a civilian airport traffic pattern--I digress).

Anyway, decend at cruise (or slightly less) power, airspeed at top of the green arc, prop setting 2400 (or whatever I had at cruise). *Level off at pattern altitude 2-3 miles downwind of the airport (approach end). *Keep current power settings and aircraft will slow to cruise airspeed by the time you are over the approach end of the runway. *At anywhere over the runway, roll into a 45-60 degree bank, 2-3 g level turn, throttle back to near idle (12-15 in manifold pressure is a guess--as I'm thinking about it I realize I must not really pay any attention to my throttle setting).

I will decrease my bank angle as the turn progresses in order to allow my roll out on downwind to be an appropriate distance from the runway. The higher you are flying the pattern, the wider you will be on downwind. This is all by sight picture: I can show it to you, but I cannot put it into words.

*The loaded turn will easily slow me down to 100 kts by the time I roll out on downwind. *At this point I will close the throttle, prop full forward. Slow to flap speed, full flaps, slow to approx 80 kts by the 45 degree point beyond the intended touchdown point. *Roll into approx 30 degree descending turn. Just as you learned in "turns about a point", the downwind portion of the turn is the steepest bank, so that the bank angle will gradually diminish as the turn progresses. *I will maintain 75 to 80 kt until rolled out on short final.*

I realize now that I have written all that, here are the key points:*
1. the prop control requires minimal management and almost no thought.
2. *This tight, high-entry speed, rapid-deceleration, power-off pattern would not be as easy with a fixed-pitch prop.
 
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Acro

Another GREAT advantage with a c/s prop is the added performance and RPM-control when flying acro.
You just set the RPM you want before starting and leave it there. (typical 2500 RPM for me)
No worries about overspeeding when the nose points down like you would with a fixed prop.
In my book, that is one of the best features of the c/s prop.

Another one is the great slowdown abilities, for example during landingpatters and during formation flying.

The downsides are cost, weight and more complex system.

In my book, the downsides is by far outnumbered of the upsides. Go for it!
 
I must agree with the majority: the constant speed adds SYSTEMS complexity, but PROCEDURAL simplicity.

I prefer to enter the pattern from an overhead approach. (OK, call it UPWIND leg for any of you who say that an overhead approach is not a recognized term for a civilian airport traffic pattern--I digress).

Anyway, decend at cruise (or slightly less) power, airspeed at top of the green arc, prop setting 2400 (or whatever I had at cruise). *Level off at pattern altitude 2-3 miles downwind of the airport (approach end). *Keep current power settings and aircraft will slow to cruise airspeed by the time you are over the approach end of the runway. *At anywhere over the runway, roll into a 45-60 degree bank, 2-3 g level turn, throttle back to near idle (12-15 in manifold pressure is a guess--as I'm thinking about it I realize I must not really pay any attention to my throttle setting).

I will decrease my bank angle as the turn progresses in order to allow my roll out on downwind to be an appropriate distance from the runway. The higher you are flying the pattern, the wider you will be on downwind. This is all by sight picture: I can show it to you, but I cannot put it into words.

*The loaded turn will easily slow me down to 100 kts by the time I roll out on downwind. *At this point I will close the throttle, prop full forward. Slow to flap speed, full flaps, slow to approx 80 kts by the 45 degree point beyond the intended touchdown point. *Roll into approx 30 degree descending turn. Just as you learned in "turns about a point", the downwind portion of the turn is the steepest bank, so that the bank angle will gradually diminish as the turn progresses. *I will maintain 75 to 80 kt until rolled out on short final.*

I realize now that I have written all that, here are the key points:*
1. the prop control requires minimal management and almost no thought.
2. *This tight, high-entry speed, rapid-deceleration, power-off pattern would not be as easy with a fixed-pitch prop.

From the Airman's Information Manual

OVERHEAD MANEUVER− A series of predeter-
mined maneuvers prescribed for aircraft (often in
formation) for entry into the visual flight rules (VFR)
traffic pattern and to proceed to a landing. An
overhead maneuver is not an instrument flight rules
(IFR) approach procedure. An aircraft executing an
overhead maneuver is considered VFR and the IFR
flight plan is cancelled when the aircraft reaches the
?initial point? on the initial approach portion of the
maneuver.

Many pilots may not be familiar with the "overhead" approach, but I have found that it is readily accepted by others in the pattern if you take a moment to describe what you intend to do: For example, "Smokey flight will enter on runway heading at pattern altitude and break to the left downwind from over the numbers."
If you have a FP prop you will need to slap the throttle to idle at the break or you will have a heck of a time getting down to flap speed. Now, with a CS you can fly initial at Vne, slap the throttle to idle at the break. Use 5.9 G's in the break, flaps down abeam the numbers as you begin the turn to final. Slip as necessary to flare at 70 knots as you cross the threshold.:rolleyes:
OK, you can ease off a little, but my point is that the CS gives you a lot more flexibility and control in the pattern, flying formation and doing acro. I would give up 20 horsepower before I gave up my CS!:cool:
 
From the Airman's Information Manual

OVERHEAD MANEUVER− A series of predeter-
mined maneuvers prescribed for aircraft (often in
formation) for entry into the visual flight rules (VFR)
traffic pattern and to proceed to a landing. An
overhead maneuver is not an instrument flight rules
(IFR) approach procedure. An aircraft executing an
overhead maneuver is considered VFR and the IFR
flight plan is cancelled when the aircraft reaches the
?initial point? on the initial approach portion of the
maneuver.

Thanks for that reference. I can't remember where (and whether it happened to me or I heard someone tell the story--probably the latter) but I recall the story of someone being chastized over the radio by some unknowing individual "this isn't a military field" (or something like that.)
 
The extra lever of CS vrs FP is a non event.

The 3 factors in the decision to go CS vrs FP are COST, WEIGHT and PERFORMANCE.

I've had CS and deliberately went FP out of cost, weight and complexity issues. But nothing comes totally free, I miss the CS advantage on take off on a hot summer day. Climb is not a major factor, let the FP wind up to 2400 at WOT and it climbs very well. I've made it to 10,000' in a bit over 8 minutes which is not too shabby, but not on a hot summer day. In cruise the CS probably can be tweaked better running LOP but LOP works with FP quite well.

The airplane is a much better glider with FP. Speed control in the pattern requires some attention and planning, but like running LOP, it is quite manageable.

I prefer the slightly aft CG situation with FP. (the Catto weighs just 16#) The constant speed prop can weigh 55+# and that makes for a nose heavy airplane with the resulting plop on-the-nose gear with the A models.

Much to think about....figure out your mission and go for it. Either way, these airplanes are a delight to fly, there's nothing on the market to compare it with. Van has designed a Total Performance machine par none.
 
Thanks for the input. I am getting more comfortable hearing your thoughts.

Flyeyes...or anybody else...please tell me about the power settings you use in the pattern. My transition training taught a very stable approach as follows...

Once you have the prop control full forward (in the pattern), you simply forget about it. You are flying a throttle only.

As to "stable approaches"... use whatever power setting works for you. Personally, I fly speed, not rate of descent. I am also power off abeam the numbers, so I'm going down pretty steep just to maintain my target airspeed.
 
...The airplane is a much better glider with FP....

Depends... One of the advantages of a CS is in the "engine out" scenario. if you still have oil pressure (or not, with a counterweighted model), you can pull the prop back to low RPM and the glide is SUBSTANTIALLY improved. If you run out of fuel with a CS prop, the first action should be to pull the prop all the way back - you pretty much double your glide


...I prefer the slightly aft CG situation with FP. (the Catto weighs just 16#) The constant speed prop can weigh 55+# and that makes for a nose heavy airplane with the resulting plop on-the-nose gear with the A models...

Again, depends. As the builder, YOU control the CG. A FP could be built nose heavy, or a CS could be built tail heavy. Absolutely agree that the CS add a bunch of weight though.
 
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