Hello Everyone.

New to the forum. Always looking for possible upgrades. My plane flies a Hartzell 80", three blade. Lately I have been reading on MT props, and they look interesting. Besides, the eye candy factor, why would you choose the 3 blade over the 2 blade. On their website, the 2 blade seems to be a better performer & lighter. In the future, I would like to bolt on a 550 engine. Would a 3 blade be a better option then?

Rgs,

Patrick.

Hola Patrick, I have flown the 182 with a 2 blade MT and a 3 blade MT.
I like the 2 blade better, quicker acceleration, and its an airbrake when pulling power and giving full pitch.
Performance wise I like those factors for the kind of flying I do.
3 blade, looks nice and more ground clearance.
No matter you choose, MT propellers are great, , performers, super smooth, high quality and durable.

The three blade will be quieter and perceived to be smoother inside the cabin, as the shorter blades are turning slower at the tip, and three smaller pressure pulses hit the cabin instead of two larger. With big horsepower engines, three blade or more blades may be needed to put the power down.

motoadve wrote:Hola Patrick, I have flown the 182 with a 2 blade MT and a 3 blade MT.
I like the 2 blade better, quicker acceleration, and its an airbrake when pulling power and giving full pitch.
Performance wise I like those factors for the kind of flying I do.
3 blade, looks nice and more ground clearance.
No matter you choose, MT propellers are great, , performers, super smooth, high quality and durable.

The 3 blade is even more of a airbrake - on final giving full pitch you can really feel it - you slide forward in your seat if you don't have your seat-belt tight (not like fly out of your seat - but you do feel the forward momentum on your body as the airframe slows down suddenly). And as far as the quicker acceleration... I thought in general the 3 blade pulled harder and therefore had quicker acceleration - but in cruise the 2 blade out performs the 3 blade as there is less drag.

I have the 2-blade MT on my Husky and love it! When you pull the throttle, it's got incredible braking action - It's taken some to get used to, but I like it! Mine was balanced and it is the smoothest prop/engine combo I have ever flown. I would highly recommend the 2-blade.

Cheers,

Jim

Anytime I see these discussions I always think back to when I flew beech 18’s. 450hp and they had 2 bladed props. So unless you really need to climb, say floats, heavy, high alt. Two is cheaper, lighter, easier to de cowl the plane and can prob handle the power. Three does one thing waaay better, it looks great.

For the 180 series there is no more ground clearance with the three blade. they are the exact same blades. One of them has two blades and the other has three of them. 83 inches. Lots of three blades that is true and they do have more clearance with shorter blades but not on this particular model.

I have flown hundreds of hours with both. The three blade pulled harder and the two blade is faster obviously. Ive contemplated this topic immensely and already sold my three for a two. I decided today as I was climbing slightly loaded to 10.5 to get over a pass, that out west I want the three blade. If I were at sea level mostly, the plane is already off the ground so quickly that it doesn’t matter and there are hardly mountains to climb over. I also believe there would be less of a speed penalty with the three blade when you’re up in thin air. Thats my final answer. I wish I didn’t sell the three blade and gave the two some time to see if it was the right fit.

As far as weight, the two blade doesn’t work on the lightweight starters for io520 or non low compression o520s. I had an expensive kickback there that probably wouldn’t have happened with a three blade. Now I have a starter that’s 10 pounds heavier but a light prop. Or you can have the light starter and the slightly heavier prop. Not a ton of difference but a little cg move.

Anyway that’s my .02. Anyone selling a used MT three blade?

ington6 wrote:For the 180 series there is no more ground clearance with the three blade. they are the exact same blades. One of them has two blades and the other has three of them. 83 inches. Lots of three blades that is true and they do have more clearance with shorter blades but not on this particular model.

I have flown hundreds of hours with both. The three blade pulled harder and the two blade is faster obviously. Ive contemplated this topic immensely and already sold my three for a two. I decided today as I was climbing slightly loaded to 10.5 to get over a pass, that out west I want the three blade. If I were at sea level mostly, the plane is already off the ground so quickly that it doesn’t matter and there are hardly mountains to climb over. I also believe there would be less of a speed penalty with the three blade when you’re up in thin air. Thats my final answer. I wish I didn’t sell the three blade and gave the two some time to see if it was the right fit.

As far as weight, the two blade doesn’t work on the lightweight starters for io520 or non low compression o520s. I had an expensive kickback there that probably wouldn’t have happened with a three blade. Now I have a starter that’s 10 pounds heavier but a light prop. Or you can have the light starter and the slightly heavier prop. Not a ton of difference but a little cg move.

Anyway that’s my .02. Anyone selling a used MT three blade?

^^^ this

Like ington, I have hundreds of hours in both. I've owned multiples of each, and I've flown friends ships with others iterations.
I've flown them on 470's, and on 520's
And although I like them fine enough, I wouldn't label myself a fanboy.
At the end of the day it comes down to 3 things. Power, mission, and preference.
You need more power to turn the 3 blade, because as ington points out, they're the exact same blade... so ya... no different ground clearance.
The 3 blade will haul a better load every time, and will get off shorter in most but not all ships. That is because if the CG favors a 2 blade, a good stick will get it off the ground shorter with that prop (assuming reasonably light loads). You are never at 100% efficiency on the take off roll, and CG can easily outweigh any thrust gains.
If the CG favors a 2 blade, and you are an 'in tune' pilot, you will prefer the way it flies as well, unless you just need the brute grunt of the 3 blade.
I am not sure I agree with the starter dilemma completely. ING is probably correct in that the flywheel effect of the 3 blade would have saved his starter adapter, but I am of the opinion that properly timed and running engines do not decide to just start running backwards mid stride. Keep it turning fwd, and the starter adapter doesn't care if you even have a prop...
These are both really good props. Buy the right one for the engine and mission you are in today, not the future. Trade if either of those parameters changes.
I tend to be a 'weight weenie' and I really appreciate a good CG, but in the end, I sold the 2 blade and kept the 3. There is just that much difference in the 'tractor factor'

Take care, Rob

As a side note,
These are not turbines.
If you are braking by choping the throttle, I'd recommend keeping an eye on the cht's.
That fun will end when you start buying cylinders.
These are draggy airplanes, it doesn't take much forethought to slow em up.

Like many, I too have flown both. But not on the same plane.

I currently own a 2 blade on my 180, which I'd sell. Its a great wheel prop, cruises much faster than the 88" 2 blade McCauley that came off. However, I took a big loss on floats, which is why I'll likely sell it, when I'm not too lazy to take it off and post it.

I've flown 3 blade MT on floats, and I was very happy with that, would do that again.

Another thing to know about these props, is as a result of the less mass, not only do they not have as much flywheel effect, but they also spool up amazingly fast.
It is my opinion that this is why you can do all the fishing scale, strain gauge style pull tests you want and find props that in full throttle will pull a higher static amount, but in the real world of advancing throttle on the roll, these things get to the business faster. Couple that with a better CG, and these things are tough to beat. The 2 bladers spool up so fast that when pouring the coals too hard I often wondered if the fast advancement was hard on the crank and weights. Probably not, and not quite 2 stroke fast, but startlingly fast for a big 6.

Take care, Rob

Another thing… I assumed you had an io520 but couldn’t really tell looking back. IF you have the low compression pponk there is only one option, two blade. Legally you can use either but they recommend more hp. If you have 8.5:1 compression 470-50 or an io520 you can go with a two blade or three blade. As I said, my two blade was great at sea level and light. Add just a little weight and altitude and I now see where the three shined. Depends on the mission.

ington6 wrote:.... IF you have the low compression pponk there is only one option, two blade. Legally you can use either but they recommend more hp. ....

Not sure that's not correct, at least for a 180.
As far as I know, the Ponk stc for the 180 only lists 3 blade props.
Guys have gotten the C66 2 (and maybe the C58?) 2 blade props field approved--
someone told me those are on the stc for the C182 but not for the 180.

hotrod180 wrote:

ington6 wrote:.... IF you have the low compression pponk there is only one option, two blade. Legally you can use either but they recommend more hp. ....

Not sure that's not correct, at least for a 180.
As far as I know, the Ponk stc for the 180 only lists 3 blade props.
Guys have gotten the C66 2 (and maybe the C58?) 2 blade props field approved--
someone told me those are on the stc for the C182 but not for the 180.

Lots of confusion and misinformation bumbling about on this thread, so I hope I dont add to it...

First: there is no longer a Pponk STC. North Point bought the STC and it's now called the XP470.

The STC was NOT for any prop. It's an STC (engine) to modify an engine, and an STC (airframe) to install it in an aircraft.

The MT prop installation was/is covered by an STC originally created by Bob Minnis for Larry of Flight Resource. This was a golden ticket STC (which probably wont ever happen again) as it covered an unheard of number of aircraft.

The Pponk STC created by Steve Knopp (Knopp spelt backwards) used 7.5:1 pistons as opposed to the 7:1 in the 470. There was NEVER a "high compression” Pponk, meaning the 8.5:1 were not allowed with the STC. When Steve asked if he could also include the higher 8.5:1 pistons, the FAA told him it would take much much longer, so he said sod it.

Since then, several DER's have been providing approval for the use of the higher 8.5:1s. This is now common place. It's important to note that these pistons are really nothing special as they are just the stock pistons in an IO-520.

With MT's, broken starter adapters due to kickbacks are indeed an issue. I can't say that 3B's are less prone to a broken adapters as in my experience I've seen more happen on the 3B than the 2B. I guess in "theory" this makes sense, but not enough for me to want to keep a 3B.

As Rob said, I too believe that these issues are due to poor timing. Anyone who has ever timed the mags on a big Cont knows precision is hard, and if you're lazy, you can get it pretty far off by not trying hard. When timing the mags, I use a laser down the case seam shooting on the Mag Timing Tool from Cammcoak. This method seems to NET the most accurate results. http://www.cammcoak.com/

When running an MT (and an aversion to replacing adapters) I think the best setup is a Shower of Sparks on one side, with a Surefly on the other. After that, if you want more piece of mind, skip the Sky-tec for the stock energizer starter. I've been swapping back and forth for the weight savings, but since I run the Shower of Sparks, Im currently comfortable with the Sky-tec.

As far as the OP’s question: I'm certainly no expert, but I have installed more than my fair share of MTs, both 2B and 3B.

On my personal bird (which is pretty much a museum piece now as all I seem to do these days is make other guy's dreams come true) I have been running MT's since 2012. Back in the day, when you called Flight Resource, the party line seemed to be the magical 300HP line. Over that #, the 3B was THE only one to run. They seem to have quietly receeded on this front. I have seen many folks now choosing the 2B regardless of HP and being much happier.

I started with a 2B (because I had a stock 470,) switched to the 3B when I put in the 300+ HP O-520, then have switched back to a 2B when I finally could look myself in the mirror and admit it flew (my bird) worse. After over a decade of installing, flying customers birds, and my own, here is the conclusion I have come up with (for me.)

2B is for pragmatists; 3B is for ego.

When we build these gutted "utility" birds, there is for sure a consequence, (too negative for some) which is CG. Everyone fixates over the low weight, but the negative effect of a forward CG can not be overstated. I've been involved with too many of these now not to know it the case.

For me, the 2B MT is pretty much a must in these iterations. Sure the 3B Mac 401 pulls like heck and looks really cool, but on a gutted 180/185, just makes a plane (if you do an honest comparison) that isn't that nice to fly (balance wise.) All these anecdotal reports about the 3B Voyager are intriguing, but the math is the math. For the kind of birds I have been involved with (IMO) these 3B heavy props are too heavy... this includes the 3B MT.

Moreover, Rob's point above, although nuanced, is spot on and rarely taken into consideration. The MT spools up so fast it always puts a smile on one's face... you "fly" an MT bird differently than a heavy alum prop. (to one's advantage.)

Yes there are some disadvantages. MT's early leading edge was very poor and showed abuse from hitting just air... MT also switched their paint vendor a couple of years ago, and many of the props sluffed off paint with just a hint of rain. I was involved with one of these props and MT Germany express shipped a new replacement at no cost to the customer. My first prop had the issue with the bolts, and MT Germany paid for it to be removed, paid for an OH, paid for shipping (both ways) and then paid for it to be reinstalled. Pretty good cust service IMO. So NET NET, I've been pretty happy and feel that they stand behind the props... ALso, now with McFarlane in the driver seat, there is even more confidence as an owner. NET NET, I have found the "web" stories not to be the case (for me)

We all have our own opinions, but for me, here is why I like the 2B MT:

• Cheaper (than the 3B)
• Smooooooth
• Much lighter
• More responsive
• Faster in cruise
• Much quieter (I never have wanted to be "that guy")

Yes I miss the "look" of the 3B, but the 13 or 14lbs off the nose really did help and makes my bird fly more balanced... and with a 3B MT retail now at $21.8k delivered, better for less seems like a good option to me.

At this stage in my life, Im trying to put the ego aside, and have been chasing the better, more balanced airplane. Lately, the most important thing I'm after is a "properly" rigged Cessna, with the C.G. in the sweet spot. If a bobble makes it faster, climbs to an altitude quicker, or takes off a wee bit shorter BUT it does this at a detriment to the flight characteristics, Im not interested.

If a better climb at altitude is what one is after, then I would look in the WingX direction rather than adding another couple of #'s at Sta -45. I found the addition of the WingX to be pretty impressive in the climb dept.

All that said… the thing I DO love about my opinions is that I find they are constantly changing. I reserve the right to change my mind. LOL

...oh... and when Hartzell comes out with the composite Voyager, this conversation may be mute... But time will tell.

Good post. This is why I won’t move the battery to the firewall.
I’ve got Monarch mains and aux, (97 gal). With two up front, full fuel, and my tool bag in the ext baggage, I’m right at fwd cg. Not very efficient. Why make it worse to save ten pounds.

but since I run the Shower of Sparks, Im currently comfortable with the Sky-tec.

Good post since I'm running a Pponk (Northpoint) and 2B MT plus just added the Surefly SIM. I am still looking at the Skytec ST5 that I purchased 6 or more years ago sitting on the shelf. Maybe won't try to trade for something else after all.

'Mornin' Greg,

Great post. Lot's of great information, I agree with 99% of it (only real points of contention being preferential matters).

You are correct, ing mis spoke on what's legal to run on a 'Pponk'd engine. I think we have both ran most of the conceivable combinations in this thread. And of course, I don't think HR was suggesting that the Pponk STC was for any propeller, but merely pointing out (correctly) that the last version of the STC as it was, listed only 3 propellors in it's Limitations and Conditions. Mine is an older one that only lists the Mac.

100% agree with you that the 2B is going to make a better flying machine in virtually any 'wagon. And the more you try to be weight conscientious the more the 2B is going to make an impact. Simple CG101 here. Almost very ounce we can lighten up in a wagon happens behind the CG, and all of it behind the Prop. Where that fits with regard to propellor selection sits squarely on the mission profile and the pilot's preferences.

Like you I started on 2B's because then I had a stock O-470J and it was FR's opinion that 300 HP was the magic number to be able to turn a 3B. The airplane world is funny, and hangs their hats on HP with no mention of torque, when I ran the fresh Pponk with the 2B I quickly found that it was not enough prop to make use of the newly available power.

This is a pretty important thing for one in this position to wrap their mind around, because the only real reason for building a more powerful power plant is to turn a more capable propellor. Without a more capable propellor, more power yields nothing but more money spent.

No doubt the 2B gave a better CG for joy flights, no doubt either pulled exceptionally well, and by virtue of their quick response on the take off roll, regularly beat the (then) king of the Pponk props off the ground (the Big Mac) But when you really needed to convert all the power you had available in a stout 520, the 2B just falls short. It does the first 90% as good or even better than the 3B. It's that last couple hundred pounds, when your in the knee high grass on a few hundred feet (or as float flyers have found) last bit of excess drag, that really needs it all.

Let's go back to your 'looking glass' and FWIW, I actually prefer the look of a 2B on a wagon, but am not vain enough to put what looks better on there, I want what snorts it out of a 'uh oh hole' better... anyway, looking in the mirror, or friends mirrors, aren't most of these conversions you are doing running from pavement to pavement with a little grass (manicured) sprinkled in? Do you really think this is the mission profile that really tests the limits of the heftier 520-550's? Doubtful... so to my way of thinking, it's not surprising at all to see the 2B better received here. But to dismiss the 3B as eye candy, just really suggests one of 2 scenarios, lack of grasp on the physics, or lack of need for the physics.
You simply can't appreciate the extra oomph if you don't ever fly in a condition that requires it, but every time you fly the CG difference is there.

So why did I pick the lesser of the sweet flying MT's? because all of it's a compromise. There are several issues (like the life limits of an MT that everyone conveniently ignores) that I really don't like about these props, but yet it's the one I chose. Compromise. I fly beyond what is normally considered heavy for work, so have a decent grasp on a good flyer, and it is one of my most highly sought after components in an aircraft (sound familiar?) but in my wagon as sweet as I would like it to fly, the reality is that it's most important mission is to take myself, my wife, the dog, pac boat and more gear than I am going to advertise here, way way off the grid and in to as many 'uh-oh holes' as I can fish, hunt or camp at... you know... the ones that once you successfully shut down in, you said "uh oh... hope we don't have to leave anything behind to get back out of here ) That is my reality. It's why I work all season long. If a STOL event on an airport with 5 measured gallons of gas in the tanks was my jam I'd be all over a 2B. If a weekend flyer, with 2 up going from breakfast to burger joints on the coast was my jam, again it'd be the 2B, no doubt in my mind. If I had a second wagon (came really close to snapping up Caulkins old 53) that I kept up north, the one down here would probably wear a 2B. But for now, this is my compromise.

Like you I am beside myself waiting for the composite Voyager, damned sheathed wood is not for the SW...

Take care, Rob

Mudwagon wrote:Good post. This is why I won’t move the battery to the firewall.
I’ve got Monarch mains and aux, (97 gal). With two up front, full fuel, and my tool bag in the ext baggage, I’m right at fwd cg. Not very efficient. Why make it worse to save ten pounds.

Mud,

If your Wagon is still wearing the metal in your avatar, you could go firewall EarthX, and MT 2B, and end up with a better, prop, a better start (short cable run), lose a heck of a lot more than 10#, and still have an exceptional CG.... less really is more with these things.

Take care, Rob

*That should have said, a good CG. Exceptional would of course be the aft limit in your mission profile.

Agree these aren’t that great to fly with a fwd CG and one or two people with a heavy prop, but I typically hit aft CG limits well before I get to gross weight.

A lighter prop would make this even worse.

After a lot of comparing, talking to MT, weighing the Pros/Cons, etc...I ended up with the 2 blade on my 0-520 180K. I am very happy with it and it's performance. It is wonderfully smooth and I was willing to give up the extra 50 feet of takeoff performance of the 3 blade for the faster cruise, lighter weight and price savings of the 2 blade. Can't go wrong with either one I bet but the guys at MT really thought I would be happier with the 2 blade so I took their advice as well.