Advise on variable pitch prop

[coodem]

I might have the chance to join a syndicate with a katana D20. Subject to my check ride, and me being happy with everything.

Now I have been reading up a bit about the aircraft and believe it has a variable pitch prop. I have heard of them, but never flown anything with one.

Can anyone give pointers/procedures. I just want to try understand it a bit more by people with real experience. Rather than reading from a textbook.

Is it hard to get used to, does it add more of a workload.

Thanking you all in advance

[Beagle-eye]

Cooderm

Never flown a katana but have a goodly number of hours on Pipers (PA 24 and PA 32) both with VP.

Basically you need to set the RPM with the throttle and then the pitch with the pitch knob. There will be basic numbers for take off/climb and whilst in the cruise. You need to monitor it during the climb as it will need adjustment as altitude changes.

Main thing to look out for is that it is easy to over-rev the engine in the descent if you forget the pitch control.

Procedures may vary with aircraft type, but, once you get used to the extra step, it’s quite straight forward.

Cheers, B-E

[FlyingForFun]

Shouldn't take more than an hour or two to get used to. Basically, your throttle controls the manifold pressure (MP), and you have an extra lever, the prop lever, to control the rpm. Instead of learning one number for each power setting (e.g. 1600rpm for base leg or whatever you use on your current type) you have two to learn (e.g. 16" MP, 2500rpm). You need to know what order to move the levers in (prop then throttle if increasing power, throttle then prop if decreasing it is a good starting point) but that just about covers it.

Of course a good instructor who knows the type will be able to give you specific pointers on the aircraft you are thinking of buying. There's a lot more to the theory than this, but you don't need to know the theory to be able to get started on the aircraft. But do read a good textbook for the theory, too, to get the most out of it.

Having said that, isn't the D20 a single-lever control??? In which case, there's only one lever to move, just like your C152 - as you move it forward, it increases both the throttle and the prop settings. If this is the case, the only real difference between this and a fixed-pitch prop is that the engine note doesn't change if you alter your airspeed.

Maybe someone who's flown a D20 will have something more specific for you.

FFF
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[Final 3 Greens]

Basically you need to set the RPM with the throttle and then the pitch with the pitch knob. There will be basic numbers for take off/climb and whilst in the cruise. You need to monitor it during the climb as it will need adjustment as altitude changes.??????

Surely you mean set the manifold pressure with the power lever (throttle) and the rpm with the prop lever (what the hell is a pitch knob?)

I've only flown a DV20 Katana and can't speak for the DA20, but IIRC the DV20 has a Hoffman prop. It had a seperate throttle and prop control.

It was a long time ago, but IIRC the power (manifold pressure) was not reduced in the climb, but the rpm was reduced. This is a little unusual to those of us brought up on Pipers, but nonetheless was the POH procedure.

To answer your question, no it will not greatly add to your workload, but you'll need an hour or two to get the new procedure into memory.

Nice aeroplane.

[Beagle-eye]

Basically you need to set the RPM with the throttle and then the pitch with the pitch knob. There will be basic numbers for take off/climb and whilst in the cruise. You need to monitor it during the climb as it will need adjustment as altitude changes.??????

Sorry. Was trying to keep it simple.

[Cricket23]

Hi,

I learned on a Katana and now have 80hrs on type (not much in the great scheme of things tho'). IMHO it doesn't really add a great deal to your workload, although it is important to ensure that you have the prop fully forward when on finals just in case you have to go-around. What I do is put the prop forward when turning base - pretty much at the same point when I'm thinking about throttling back.

You should be ok once you've had the suitable time on any differences training. Go for it.

Edited to add that the DA20 does indeed have separate prop and throttle levers. (But there's no mixture control to 'worry' about, so at least that eases the workload slightly).


C23

[strafer]

Coodem,

I asked a similar question about a year ago and was pointed towards the John Deakin columns on Avweb.

You could do worse than read this one: http://www.avweb.com/news/columns/182081-1.html

[MIKECR]

If I remember correctly there were only really two settings I ever used - 24 squared for fast cruise and 22 squared for economy. Other than that, full rpm on t/o and reduce to 22 or 24 rpm for the climb. When established on final approach, increase to full rpm again incase of a go around.

[coodem]

Thanks for the replies. It all sounds a bit confusing, The principle all makes sense, as you can make the engine a lot more ecomical through the RPM range, as well as altitude. I guess like everything it all becomes clear once you are doing the real thing. I will let you all know how I got on, later this week. Assuming the weather is in my favour

[Cricket23]

It may sound confusing, but in practice it's really very simple. Like most things in life, once somebody has shown you how to do it, it's easy.

All the best, hope you enjoy the flight. As has been said a Katana is lovely to fly. Also, the viz from the cockpit is excellent.

C23

[IO540]

We may need to be careful here.

I know nothing about a Katana (other than it is a composite 2-seater) but my son has one on FS2004 and the prop pitch control turns the blades around when sitting on the ground! This suggests that either it's a duff FS2004 model, or the prop is not the standard constant-speed prop.

Assuming a standard CS prop however, this subject is massively over-cooked. You climb at max RPM to top of climb, then set RPM back to cruise RPM and leave it there until short final when it goes back to the "max" lever position. For high altitude operation, say above 10,000ft, one goes back to max RPM, to give the engine as much "suck" as possible. That's it!

Some engines have operating limits e.g. the IO-540-C4 should not have MP above 23" if the RPM is below 2300, but above 2300 one can have any MP. Or something like that; I have the chart somewhere.

[RYR-738-JOCKEY]

Beagle-eye wrote: "Basically you need to set the RPM with the throttle and then the pitch with the pitch knob. There will be basic numbers for take off/climb and whilst in the cruise. You need to monitor it during the climb as it will need adjustment as altitude changes."
and
"Sorry. Was trying to keep it simple."

Just to make this completely clear to you for your second session with variable prop. You don't adjust RPM with the throttle, you adjust the manifold pressure. Secondly, you do adjust the prop pitch, but more importantly, the RPM with the prop lever (the one you refer to as pitch knob).

Much easier in a jet....

[172driver]

Think of a variable pitch prop a bit like being able to shift gears in a car. In other words, you can adjust the power you need. Others above have already explained how. Once tried, you'll never want to go back to a fixed pitch (writing this just landed after tooling around the mountains of southern Spain, in, you guessed it, a 172 RG with a variable pitch prop :ok: )

One thing, though. On a standard CAA/JAA/FAA license you will need 'differences training' / 'complex endorsement' to legally fly a type with a variable pitch prop.

[Fuji Abound]

One other pointer which I know you havent asked but you did say I have been asked to join a VP group .. .. ..

VP hubs can be problematical and can also be expensive to repair. They will also add to the service costs. In my view a good group will have set aside some funds to deal with these issues and may build on these funds with a contibution out of each flying hour.

Excerising the prop - essentially ensuring oil is reaching the governor is a common additional pre flight check. IMO it is often over done by prolonged excercising when the oil is potentially cold. You will want to be aware of the correct pre-flight checks including a quick check during the walk around to ensure the hub hasnt cracked. Cracked hubs are also not unknown - the first sign will be the red tell tale oil used to help identify this sort of problem.

[ShyTorque]

BTW, Are we talking variable pitch, or constant speed in this case?

[Final 3 Greens]

ShyTorque

My handling notes (from 1997) say hydraulic, constant speed, propellor.

Slightly unusual operation, in that it is acceptable in some regimes of flight (e.g. the climb) to reduce rpm without reducing manifold pressure.

IO540

Assuming a standard CS prop however, this subject is massively over-cooked. You climb at max RPM to top of climb, then set RPM back to cruise RPM and leave it there until short final when it goes back to the "max" lever position.

Not on the DV20 - please see above.