jb1842 Posted January 10, 2015 Report Posted January 10, 2015 Hi. First post here, but I've been lurking for the last couple of weeks. I'm currently the owner of a Cessna 150, and I am looking to upgrade. After much research, it seems like the M20C is the perfect aircraft for me. I'm hoping to have my 150 sold in the next month, and will be looking to purchase a Mooney in the spring, early summer. I've got a general idea of things to look for in my aircraft search, but I would like some info. So what are the advantages/disadvantages of 2 and 3 propellers? It may sound like a not very important question, but it seems like its around a 50/50 split of available aircraft that have either of them. Thanks. Quote
jrwilson Posted January 10, 2015 Report Posted January 10, 2015 2 blades are slightly faster, 3 blades climb slightly faster and look cooler. Some people say 2 blades are smoother, but that is solved by prop balancing. Not sure but I think some 2 blades require ongoing inspections for some AD. Quote
Marauder Posted January 10, 2015 Report Posted January 10, 2015 One disadvantage of a 3 blade is one more prop to overhaul. Quote
Jibsheet1 Posted January 10, 2015 Report Posted January 10, 2015 I believe the 3 blade prop gives a few inches extra ground clearance when taxiing. Quote
tony Posted January 10, 2015 Report Posted January 10, 2015 the three bladed prop moves the red arc (2100-2350 RPM) down to 2/3 of the engine RPM (1400-1550), adds drag at cruise, better climb performance.  However, I really don't think it should influence your decision to buy the right aircraft for you.  I would worry more about the eddy current inspection on the hub. Quote
Hank Posted January 10, 2015 Report Posted January 10, 2015 My C with a 3-blade Hartzell has a red zone 2000-2250 RPM, and like many is placarded for "no continuos operation below 15" manifold pressure" but the only photo I can find right now is too blurry to read the rest. But 2300 is my low level lunch run setting. Also, the blades are the same length as on 2-bladed props, no additional ground clearance. Other brands may vary, and certainly the composite props are different. Mine is hard to measure, but I did figure it out once to be 76". It does, however, climb well, and with the guppy mouth closure and 201 windshield, I make book speed. So it may cost 2-3 knots at cruise. Some people complain about vibration, but mine is pretty smooth. Get a dynamic balance if it's not smooth. Quote
Guest Posted January 10, 2015 Report Posted January 10, 2015 Propeller manufacturers being fairly smart have priced their 3 blade propellers cheaper than 2 blade versions knowing that they will sell you 50% more parts at overhaul. Clarence Quote
GeorgePerry Posted January 10, 2015 Report Posted January 10, 2015 You might find this thread useful. Â http://mooneyspace.com/topic/8-prospective-vintage-mooney-buyers/?hl=%2Bperspective+%2Bvintage Quote
triple8s Posted January 10, 2015 Report Posted January 10, 2015 I preferred the hc-c2yk and just had the ECI done as needed. No MP/rpm ranges to avoid, great cruise, lighter weight, cheaper overhaul cost and no vibration worries. place in north georgia did my ECI i would fly it down and take the crew car for lunch come back and fly home, no big deal. Cost about 300$ IIRC Quote
chrisk Posted January 10, 2015 Report Posted January 10, 2015 I would look at a C, D, E, or F. Find the best one you can and buy it. That's how I started and I ended up with a K. I'd look for an auto pilot, newer radios, frequent use, and if your lucky, a recent strip and seal on the fuel tanks. 1 Quote
47U Posted January 10, 2015 Report Posted January 10, 2015 I have the McCauley 3 blade. It's over 20 years old and was last overhauled in 2010 with only normal consumables replaced. Around $3K, if I remember... the overhaul is recommended every 5 years, but I had just gotten the airplane and it was twice that long since it had been done so during the first annual to the prop shop it went. The airplane is hangared which might make a difference. I'll agree with a little better climb, a less cruise, potential for harmonic issues (it may be as simple as installing a landing light plexiglass cover), but the big benefit I think is drag. It helps a lot to get the airplane slowed down to gear speed in the pattern. And it looks cool. 1 Quote
StinkBug Posted January 10, 2015 Report Posted January 10, 2015 Looking through the log books for the C I just bought showed that it had a 3 blade McCauley swapped on at some point, and later a 2 blade Hartzell top prop. What I found interesting was that the 3 blade weighed roughly 25lbs more than the 2 blade. Not a huge amount, but that's one more carry on sized suit case you can carry. Quote
Jeff_S Posted January 10, 2015 Report Posted January 10, 2015 You can tell the ground clearance of any prop by looking at either the original Type Certificate for the plane or the STC if it is an add-on prop. That will tell you the prop diameter, which you can then use to calculate the ground clearance. Â I had a three-blade on my J, but that's what it came with so I can't give you any comparisons. I had no problems with it and did experience great climb rates, although that is probably also because I was seldom at full gross. Quote
Bob_Belville Posted January 10, 2015 Report Posted January 10, 2015 ISTM the majority of "experts" here would opt for a modern Hartzell Scimitar 2 blade for our 4 cylinder Lycomings but other are happy with their 3 blade or the original. Â But I would not think the type prop is a big factor in choosing your vintage Mooney. Condition of airframe, engine, panel, and systems, etc. are more important. 1 Quote
jb1842 Posted January 10, 2015 Author Report Posted January 10, 2015 Thanks for all the info. I've read up on the fuel tank issues, so that is going to be a bigger concern over the propellers. I just only have experience with 2 propellers, so I don't know anything about 3. Quote
Bob_Belville Posted January 10, 2015 Report Posted January 10, 2015 2 or 3 BLADES.  Here's what 3 props look like...  1 Quote
carusoam Posted January 10, 2015 Report Posted January 10, 2015 The overall difference between two and three Bladed props is small... Compared with annual AW inspection requirements or RPM limitations due to harmonic vibrations... A two bladed prop is preferred for speed on the 200hp Moonies... A three bladed prop is preferred for speed on the 300hp Moonies... Essentially you want to look at the exact model on the airframe itself. It is too simple to ask the general question of 2 vs 3 blades.... I am a big fan of the TopProp...Scimitar shaped blades, modern hub design.... Where are you from? Best regards, -a- Quote
Hank Posted January 11, 2015 Report Posted January 11, 2015 Just got back from a beautiful afternoon refresher flight to nowhere. Just for sh!ts and giggles, I went to the next airport over (15 nm) and back for landing variety. Coming back at 2500, I left full power in (27 and a smidgen, 2700) and was indicating ~162 mph. Then I set my normal low level power 23/2300 and leaned to 50° rich. To my surprise, I only lost ~10 mph. I'm used to seeing much less than that at 3000 msl, around 135 mph. Maybe the recent fix to my carb heat is shutting it off now, but it's been partially open for a long time? Or maybe here in The South, my plane just flies 15-20 mph faster because we're in God's Country? M20-C, 3- blade Hartzell. About 50°F outside today. Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.