Excellent Wayne, thanks for posting.

Not to sound too condescending, but if it takes you longer than an hour to get comfortable with the CS prop, you're not concentrating!

I have a CS prop and O-360 (carb) on my P172D. The governor is set for 2700 rpm max. So when I take off, everything is full forward. At around 400' AGL, I reduce power. If I'm climbing out of a low elevation airport, I bring the MP back to about 25"; if I'm coming off a higher elevation airport, I just leave the throttle in all the way. Either way, then I reduce the rpm to about 2550 to climb on out. At my cruise altitude, I reduce MP to 21" and rpm to 2400. There's nothing magic about those numbers, but my engine seems smoother at 2400 rpm than lower. At the altitudes I fly here in Colorado, Wyoming, etc., I can't get much over 21" at cruise altitudes, so that's just the MP I use, even at lower altitudes. Using a higher MP raises the fuel flow without adding enough more speed to make it worth it.

For landing, I normally push the prop control in after I'm down to about 80 mph on base, but definitely after I've reduced enough MP that pushing the prop in won't change the rpm. That gets it ready for a go around, if necessary, without making more noise to annoy the neighbors.

Half a dozen circuits, including leaving the pattern a couple times to set up a short cruise, will have you wondering why you worried about it. Honest.

Cary

Cary wrote:Not to sound too condescending, but if it takes you longer than an hour to get comfortable with the CS prop, you're not concentrating! ...
Half a dozen circuits, including leaving the pattern a couple times to set up a short cruise, will have you wondering why you worried about it. Honest.

Cary

Cary- I expect that advice is right on the money. It's one of those things I've got to actually do, before I can wrap my head around it I suppose. I've always been a hands-on learner, and I'm getting pretty excited to get my hands on this.
Thanks,
-DP

I've tried to not say anything because I know nothing about running CS props. I have a measly 30hrs behind an o360 with a CS and am pretty much self taught. I screwed up and did things wrong many times but I didn't die and never hurt anything. Now I run the prop/engine almost exactly like Cary said and it is no big deal.

DP, I've only ever flown three planes with fixed pitch props: 2x 150's and 1x 172.

You'll pick it up super fast. Just be aware of any max power time limits that might apply and where your green arcs are at and you really can't go wrong. Steady and deliberate blue knob applications make an engine happier than fast and hunting ones.

Other than that basic advice (and the pretty good techniques already posted in here) I'd basically say try stuff out and figure when the plane is smooth, where it's most efficient, fast cruise, slow cruise, etc. It'll be fun for sure!

Again, be careful using specific numbers from dissimilar engines for power settings.

While the O 360 and IO 360 engines are quite similar, as I mentioned earlier, you really need to get the Lycoming booklet that came (or should have come) with that engine, and explore what combinations of MP and RPM reluctant in what percent of rated power.

In this case, I don't think you can hurt that engine by mismanaging MP and RPM, but you definitely need to know what settings equate to 75 % power! since leaning at or above that power setting is a no no.

That booklet is short and simple.

When I was flying the six and nine cylinder engines a lot, I made up a one page power setting chart, with differences in altitude, laminated it, and kept it handy in flight.

Not rocket science, but different engines have different limits and needs.

MTV

Roger that, MTV. Thanks for weighing in

I learned the mnemonic "rev up, throttle down" in ground school many years ago. It relates to changing the engine power settings. When power goes up adjust the rpm first, when power goes down adjust the throttle first.

Darinh wrote:Take it for what its worth but I read an article in the one of the recent CPA mags from either Mike Busch or that other engine guru (can't remember his name now) that said cycling was hard on an engine and was essentially pointless. He also said that a typical mag check (1700 rpm) is useless. I can't remember his reasons now but it sounded legit.

I cycle once just enough to get a very slight rpm drop then off I go... Creature of habit I guess.

Search the Pelican's Perch articles #15, 16 or 17 on Avweb. They are written by John Deakin and bust most of the old ways on props, MP, and leaning. 56 pages worth printed out but an excellent and educating read. Deakin also has and Advanced Pilot Training website where all the articles are in PDF form. I just bought a 172 with 180HP and C/S prop. I'll be followwing Deakins methods for prop and mp use.

Darinh wrote:Take it for what its worth but I read an article in the one of the recent CPA mags from either Mike Busch or that other engine guru (can't remember his name now) that said cycling was hard on an engine and was essentially pointless. He also said that a typical mag check (1700 rpm) is useless. I can't remember his reasons now but it sounded legit.

I cycle once just enough to get a very slight rpm drop then off I go... Creature of habit I guess.

Yup! Mike Busch. I believe I've seen it both in print as well as in one of his webinars. As noted, John Deakin addresses it too. Both have excellent info. Check them out!

Any more than three times and your playing with it! ,,,,,,,,,,,,,,,,,I'm sorry, I just could not pass that one up.

I usually cycle the prop twice. The first time, when there's still cold oil in the prop mechanism, the rpm reduction will be noticeably sluggish. The second time, if everything is working correctly and the warm engine oil has circulated into the prop mechanism, will be very quick. If on the first cycling, the rpm drops quickly because the oil is already warm enough, I don't even do a 2nd one. I can't think of a good reason to do a 3rd one.

Cary

I have been experimenting recently, following advice on a different thread

I can get up to 5kts extra airspeed in the cruise by running my prop coarse (lower RPM and "oversquare") and at a lower fuel flow, compared to banging along at 2300 or 2400. The engine runs noticeably colder too.

If I fly LOP at 22", 2300 and 34 L/h, I see 115 KTAS

If I fly LOP at 25", 2000 and 32 L/h, I see 120 KTAS,

I guess this must be related to the difference in drag of the prop passing through the air at higher / lower speeds, but I don't know for sure. Or maybe it's just the efficiency of the blade / engine etc.

Yes!

Over square does work! Been doing it for many years…

I think it is a combination of prop and engine.

G44




quote="Battson"]I have been experimenting recently, following advice on a different thread

I can get up to 5kts extra airspeed in the cruise by running my prop coarse (lower RPM and "oversquare") and at a lower fuel flow, compared to banging along at 2300 or 2400. The engine runs noticeably colder too.

If I fly LOP at 22", 2300 and 34 L/h, I see 115 KTAS

If I fly LOP at 25", 2000 and 32 L/h, I see 125 KTAS,

I guess this must be related to the difference in drag of the prop passing through the air at higher / lower speeds, but I don't know for sure. Or maybe it's just the efficiency of the blade / engine etc. [/quote]