3 blade vs 2 blade propeller

[Markku]

I have the 3 blade MT prop on my 78 J. I am curious if anyone has performance numbers for the 2 blade blended foil Hartzel prop. Reason I ask is that I am building a Van’s RV-7A. If I buy the Hartzel for my Mooney it would also fit the RV. Then I could decide which prop performs best on the Mooney and put the other on the RV. This gives me an option to experiment. Thanks

[Ragsf15e]

2 hours ago, Markku said:

I have the 3 blade MT prop on my 78 J. I am curious if anyone has performance numbers for the 2 blade blended foil Hartzel prop. Reason I ask is that I am building a Van’s RV-7A. If I buy the Hartzel for my Mooney it would also fit the RV. Then I could decide which prop performs best on the Mooney and put the other on the RV. This gives me an option to experiment. Thanks

It would be awesome if you could do this experiment in the Mooney because we often have this debate about how much slower (if any) the 3 blade is.

[KSMooniac]

I would wait until Hartzell finishes their new composite 2 blade 7497 profile prop and then try it on the Mooney! Looks lighter than the MT (I have one too) and should be a bit faster.

Here it is on an RV at OSH.

Sent from my LM-V600 using Tapatalk

[Markku]

Thanks for the update on the new composite. Weight savings is always a plus.

[jetdriven]

9 hours ago, KSMooniac said:

I would wait until Hartzell finishes their new composite 2 blade 7497 profile prop and then try it on the Mooney! Looks lighter than the MT (I have one too) and should be a bit faster.

Here it is on an RV at OSH.

Sent from my LM-V600 using Tapatalk
 

There were a couple or three Cardinals down at the other end where we parked at this shit that I had that problem and it looks really exciting. I want to get my hands on one.

Gammy has been installing them with their turbo STC. I wanted to ask them play if they could morph that blower STC over to the Mooney too but they were so busy I could never get a chance to ask.

[jetdriven]

It looks like it has this restriction on the RV planes.  
The following restrictions apply to the HC-M2YR-1BFP/F7497 propeller on the RV aircraft with Lycoming IO-360-A1A 200 HP engine: “Continuous operations is prohibited above 24 inches manifold pressure between 2350 and 2550 rpm.”

https://hartzellprop.com/pilots/kit-builders/rv-4-rv-6-rv-7-rv-8-io-360-standard/
 

 

 

[jetdriven]

Cardinal prop.  This this is 4000 more then a C212 prop. 
https://gami.com/props/props.php

[Pinecone]

What I had read over time is the MT 3 blade has better take off and climb performance than a metal 2 blade with almost the same cruise performance.

The metal 3 blades have better take off and climb that the 2 blades, but you lose a measureable amount of cruise speed.

I would not expect a lot of take off/climb performance increase from the Hartzell 2 blade composite, but some cruise speed increase.

I talked to Hartzell at Mooney Max and they are working on a composite 3 blade for, at least, the Ks.   Of course, they say it will be better all around than the MT.

As I understand it, for the Ks, Mooney tested every prop available at the time, and the McCauley was the fastest.

[A64Pilot]

6 minutes ago, Pinecone said:

As I understand it, for the Ks, Mooney tested every prop available at the time, and the McCauley was the fastest.

I have no data to support it, but that’s my understanding for the J’s too, but that was years ago and there are new props now.

As long as a Composite doesn’t have too much flex I don’t think performance wise that blade material makes much difference, a metal prop can have a thinner airfoil though, but a composite is almost always lighter.

In my opinion for all round utility like occasionally smacking a rock it’s hard to beat a metal prop and if cruise speed is what’s desired and for lower powered aircraft like ours a two blade is hard to beat, up the power like a TBM for instance and two blades just aren’t enough

[jetdriven]

We had Hartzell composite props on the 1900s and they have the nickel leading edge. I would say those props are a lot more durable than aluminum prop because that leading edge is tough as hell. Plus it's actually replaceable. 

[A64Pilot]

37 minutes ago, jetdriven said:

We had Hartzell composite props on the 1900s and they have the nickel leading edge. I would say those props are a lot more durable than aluminum prop because that leading edge is tough as hell. Plus it's actually replaceable. 

They do work well in small particles like sand. The UH-60 blades have a nickel leading edge too, looks neat at night under goggles in sand and dust, gives the aircraft a Halo. AH-64 blades are four titanium main spars bonded together one behind the other, but give the same effect.

https://en.wikipedia.org/wiki/Kopp–Etchells_effect

But it’s a rock or anything that makes you break out the file that I speak of, you can file out an aluminum prop, you can’t file a nickel leading edge.

[jetdriven]

Interesting.  We had small pebble dents in the leading edges occasionally, but Nickel tends to bend with a soft radius, and there are limits to where you have to replace it, but otherwise, instead of filing out small rock dings, we would get less rock dings , and the bigger ones require the blade to be repaired.

[A64Pilot]

2 hours ago, jetdriven said:

Interesting.  We had small pebble dents in the leading edges occasionally, but Nickel tends to bend with a soft radius, and there are limits to where you have to replace it, but otherwise, instead of filing out small rock dings, we would get less rock dings , and the bigger ones require the blade to be repaired.

Yeah, back to nothings perfect. Nickel because it’s extraordinarily hard wears much better with smaller stuff, but if it hits something sometimes even as small as pea gravel the props coming off to be repaired where most likely an A&P can just file the damage out of an aluminum prop.

Of course there are limits to what you can file too, and sometimes depending on where on the blade the allowed damage is quite small.

For an aircraft that only operates off of paved runways the nickel leading edge may be better, maybe not for occasional off road use though.

Blade erosion was a big deal on helicopters in the desert. The older aircraft with aluminum blades like the Huey did better than I would have thought, but there are very few Hueys out there still, none Active duty that I saw, but there were a few flying around.

[hubcap]

1 hour ago, Pinecone said:

What I had read over time is the MT 3 blade has better take off and climb performance than a metal 2 blade with almost the same cruise performance.

The metal 3 blades have better take off and climb that the 2 blades, but you lose a measureable amount of cruise speed.

I would not expect a lot of take off/climb performance increase from the Hartzell 2 blade composite, but some cruise speed increase.

I talked to Hartzell at Mooney Max and they are working on a composite 3 blade for, at least, the Ks.   Of course, they say it will be better all around than the MT.

As I understand it, for the Ks, Mooney tested every prop available at the time, and the McCauley was the fastest.

I replaced my 2-blade Hartzell with a 3-blade Hartzell because I wanted the improved climb performance, but I can’t tell that I have lost much if any speed in cruise.

[EricJ]

3 hours ago, jetdriven said:

It looks like it has this restriction on the RV planes.  
The following restrictions apply to the HC-M2YR-1BFP/F7497 propeller on the RV aircraft with Lycoming IO-360-A1A 200 HP engine: “Continuous operations is prohibited above 24 inches manifold pressure between 2350 and 2550 rpm.”

https://hartzellprop.com/pilots/kit-builders/rv-4-rv-6-rv-7-rv-8-io-360-standard/

-A1A engines don't have dynamic balance weights, so the restriction may not apply to engines that have them.

[Hank]

11 hours ago, hubcap said:

I replaced my 2-blade Hartzell with a 3-blade Hartzell because I wanted the improved climb performance, but I can’t tell that I have lost much if any speed in cruise.

The previous owner put a 3-blade Hartzell on my C, and I still true out around 145-148 KTAS. Per "the Book," I should cruise right at 165 mph (= 143 knots).

[Markku]

I put the adhesive tape on the leading edge of my MT 3 blade to protect the metal leading edge. It has held up well for almost 3 years. I talked to MT and they told me what to buy from Aircraft Spruce. Inexpensive insurance. I do love the takeoff and climb performance of the MT. It is also very smooth and removes the rpm/mp restriction I had with the McCauley. When I pull the mixture to idle cutoff the engine just stops rotating be the mass is so much less than a metal prop.

[A64Pilot]

If the tape lasts for years, then you don’t need the tape. May sound silly but the tape of course is very soft compared to nickel steel. It’s primary use is as a sacrificial wear to protect aluminum props from sand. If that tape lasts then your not going through anything that could harm nickel steel, that stuff is very wear resistant, way more than Stainless Steel.

It doesn’t hurt having it, just my experience with the stuff isn’t good largely from causing balance issues especially on helicopters. AH-64 has a 9.2 foot long tail rotor, yet I’d balance one to 1 gram. With the anti abrasion tape on it I couldn’t keep them balanced as well as I liked.

I guess operating off of grass in Fl I ought to put the tape on because I am getting wear, but my wear of course is primarily at the tip, which on my McCauley is curved and I don’t think you can tape that.