Marty--what do you have now, and which model are you going with?

Lance

Lance, My prop is a Mac 2A34 C203/90 DCA-x 88 in seaplane. I'm going with the 83 inch MT like Russ has. Sounds like it fits anything from a O470 A to a O550 on 180's.

Ok, I think that is what I have--I know it is an 88" mac.

Why are you changing, if you don't mind me asking?

I'm hoping for smoother and quieter. Also like the idea of that stainless steel leading edge.
Marty

I can guarantee that it will be quieter, those 88" props sure have a distinctive buzz.

Can't wait to hear how it works, W&B and performance-wise.

Thanks for the info

john54724 wrote:For the 2 vs 3 blade question; first our 2 and 3 blade props use exactly the same blade and exactly same diameter, so with that as a constant, the 3 blade really should have 280 or more HP to work better than the MT 2 blade.

Dominion Propeller in Anchorage is a great prop shop and has just completed the very difficult MT training to be approved to service and overhaul MT props. Just waiting now for FAA approval of application of license.

Here is a couple of YouTube videos I made last week while in Anchorage showing the MT prop with reversing option on a 200hp PA-18. Real fun and good on floats too.
http://www.youtube.com/watch?v=l2zfnPakVjU
http://www.youtube.com/watch?v=oYIvOFsGNOY

John

Ok, so the 3 blade 83" would be what I need on the 185, Io-520, turning 2850 rpm?
Money back guarantee to out perform (take off/climb) my 80" Mac 403?
Is this a significant performance boost, or would I be best to keep the Mac, it only has 6 smoh.
Anyone want to buy a Mac 403, with 6 smoh?

sideslip, the 83 inch, whether in two or 3 blade is the only 185 prop available in my understanding. Also, when I spoke with Larry at Flight Resources, he told me that on the 185's they govern them back to 2700 with the MT. 2700 is where the MT makes its best performance. You would need to call them and confirm all this. Russ

Thanks Russ,

That's interesting that there is more thrust at 285 hp than at 300 hp. With the Mac, there is a very noticable difference in pull going from 2700 to 2850.
Their blade airfoil must be quite a bit different.

Russ said it exactly correct. The MT prop is designed to have best thrust at lower RPM's. FACT: we attached a float plane with IO-520 to a digital strain guage and recorded measured static thrust with several props by starting at full power and prop at max rpm. Then on all, dial back rpm control and record thrust. Surprise!! Max thrust in the MT was obtained about 2600 +-. And the recorded thrust on the MT was higher than the 80 or 88" 2-blade props on the same plane (and made a LOT less noise). Many experts out there tell owners to run oversquare for best performance and endurance. I won't argue with Lindburg et. al. .

And 'yes' a money back satisfaction gaurantee is offered on all sales.
John

Is measuring thrust valid when the airplane is tied down. Is that not like having a car on a chasis dyno and puting oil on the drive wheel. To bad you cannot measure the thrust with the aiplane doing 50 mph. That would change your outcome a bit. I guess you could do that in a wind tunnel.

Tim

john54724 wrote:Russ said it exactly correct. The MT prop is designed to have best thrust at lower RPM's. FACT: we attached a float plane with IO-520 to a digital strain guage and recorded measured static thrust with several props by starting at full power and prop at max rpm. Then on all, dial back rpm control and record thrust. Surprise!! Max thrust in the MT was obtained about 2600 +-. And the recorded thrust on the MT was higher than the 80 or 88" 2-blade props on the same plane (and made a LOT less noise). Many experts out there tell owners to run oversquare for best performance and endurance. I won't argue with Lindburg et. al. .

And 'yes' a money back satisfaction gaurantee is offered on all sales.
John

Thanks John,

I'm really interested in trying one out!!

Did you notice if the other props were putting out less thrust at the lower rpm, ie the thrust increased the higher the rpm, all the way to redline?
I also have a digital strain gauge, so I will test the output with the Mac 403, and would be interested to see how close our numbers are(just for curiosity). We've got a fresh engine, and prop with blades rated 'A' at overhaul. Both have around 6 smoh.
Obviously more thrust would be great, but on these small amphibs, edo 2790's, the weight loss on the nose would be just as important.
I'd love to talk to a commercial operator that has float experiance with the Mac 403, 401, and the MT. Know anyone?

By the way, I installed a fixed pitch MT on a friends 90hp Champ a couple of years back, and he absolutely loved it, it totally changed the feel of the aircraft, and performed great, till he wrote the plane off. The prop was completely destroyed, as was the rest of the Champ, but the engine was fine, even though the prop hit the ground at close to max power

Sideslip, contact Larry at flight resources. He gave me the names of the guy from Alaska who tested props head to head, and a commercial ops guy from Red Lake Ont. I spoke with both. Also, I think as part of the Valdez takeoff contest there was some talk of having a prop shoot out on 185's. That's next weekend I think. Regarding 285hp vs 300 hp, remember its thrust that propel's a plane forward, not horsepower. Think diesel engines in pickups. Usually their hp rating is less than comparable gas engines, but the foot pounds of torque they produce is greater. Granted, more hp can usually turn a prop that can make more thrust than less. If you look at Pponk's website, they also speak to tip speed on props, and beyond a certain point, I think it was .92 mach, you are using horsepower to make noise and not thrust. Pponks figures involved 401 mac. They said that the 86 inch 401 produced exactly as much thrust as the 88 spinning at the same speed, and the 88 just make more noise. Isn't the 403 mac the prop that has some resonance issues at certain rpms or restricted rpm ranges?

We have the 3 blade 81” MT (we ordered the 83” but received the 81”) on our C180 with a Texas Skyways O-520. We went for the MT to keep weight off the nose as we also shifted the battery to the firewall. John and Larry both recommended the 2 blade for the 285 HP we now have, but we saw in their testing on a C185 that the 3 blade 83” gave an improvement over the 2 blade in take off and climb, which was our priority, so we went 3 blades. However the testing also showed a 5 knot loss in speed for the 3 blade over the 2 blade. We like the prop but still would have preferred the 83” and if we did it again we would probably go with their recommendation of 2 blades. Even less weight on the nose, faster and only slightly inferior on take off and climb. George Mandez in Alaska tested the 2 blade 83” MT against the 3 blade 86” Mac 401 on the same 185 on the same day and claimed the 2 Blade MT significantly out performed the 3 blade Mac 401. They eventually went for the 3 blade MT’s on their 185’s. Larry told me he prefers the 2 blade MT on his 185 on wheels and the 3 blade on his 185 on floats. So take your pick they are both good.
I did a trip recently with a 185C, ours is a 180J. He had a new IO 520D, we had a new O-520. We both had Sportsman STOL Kits, same full loads and fuel. He had an 82" 2 blade Mac. We were consistently getting off 50-60 metres (180 odd feet) before him. Only difference was the props. Cruise was the same.

Jamie G

Isn't the 403 mac the prop that has some resonance issues at certain rpms or restricted rpm ranges?

No restriction on the 403, I believe it is the Hartzell that has the restriction.

Finally had the chance to fly with the MT fully loaded. I am still very happy. Still significantly quicker on step and acceleration and better in climb than the 401 . While I definitely wasn't getting 1500 fpm, I was still easily climbing at 800, and with the big load on floats this is good. Also had a heavy takeoff on glassy water at about 75 degrees 1300 elevation, and it pulled up and out crisply. Taking off heavy from glassy water can pose a challenge for any float plane, but I was able to fly it off without any monkey motion on the controls. I need to re-learn my technique, as it seems this prop does better with just letting it accelerate and then trim it off the water. When heavy the 401 almost always needed a little tug on the yolk to want to break the water. When you pull the mixture, it stops much faster than the other prop, so on floats you really need to carry power in closer to the dock before shutting down or else be quick out the door and with the paddle. I believe with practice I will be able to land much shorter since this prop slows down fast and acts as a good speed break. Definitely a keeper and glad I made the change. Russ

From what I have read on this thread, it seams that most planes would benefit from a change to the MT. I wonder what one could expect in a 182 with stock motor. I do like that the prop for the stock motor and for a 280 hp motor are the same. If that is correct, a guy could change props and then upgrade the motor later.

Tim

Marty, any updates?

The one that showed up in early May had some shipping damage so I am waiting for another one. Hopefully it is 100% when it gets here.

Would any of you mind sharing the prices for the 2 and 3 blade props. Curious-

Airplane stuff never ceases to surprise me with it's price. This is the quote from MT I received by email on 20, May, 2010 and after some serious soul searching I will launch a similar campaign inside my billfold before taking this plunge.

Offer 205_10

Dear Mr. Dirtstrip (not my real name),

For the Tundra with the Superior XP O-360 180 hp or the similar Lycoming engine we will offer you our 2-bladed hydraulic constant speed propeller with a diameter of 205 cm (81“):

Type: MTV-15-B/205-58 USD 10,360.00
+ Spinner Assy P-271-C USD 1,330.00
+ Governor P-860-x USD 1,680.00
USD 13,370.00

MT Propeller

Note: My engine has a fixed prop now even though I ordered it with the crankshaft to accept a constant speed. So in addition to the above I will need a gear drive for the governor and hosing to the front of the engine oil port and some other minor parts. Superior Parts recommended to go with the governor from MT rather than order from them. Maybe the better match?
Hey, if this is what they get for a USD one, what would it be new?