MT versus Hartzell
 

A mate has just swapped his Hartzell for an MT prop and has lost 10KT of cruise speed. Has any one had a similar experience with the MT.

MT vs. Hartzell
 

The following is from an e-mail by Jim Ayers (MT Distributor):

I have done propeller cruise testing using a Harmon Rocket 2 with a stock Lycoming 540 engine, and on a RV-6A with a stock Lycoming O-360 180 hp engine. In normal cruise conditions, the MT 3 blade propeller for that aircraft at least matched the performance of the 2 blade Hartzell propeller for that aircraft on the same airplane with the same pilot under the same flight conditions.

The 4 blade MT Propeller on the HR2 that John Starn is talking about was a custom design for John Harmon's HR3 with a special Lycon 540 engine dyno'd at 380 hp.
Tom Gummo's HR2 has a stock Lycoming 540 engine, and the HR3 propeller is not designed for that engine. However, the price was right, and they were willing to give up the performance.

In my opinion, the 3 blade MT RV-10 propeller and spinner would be an excellent choice for your aircraft.

Next: The following is a posting from the Matronics RV E-mail postings:

Subject: Prop test 2-blade, 3-blade, 4-blade
From: JOHN STARN (jhstarn@verizon.net)
Date: Fri Jan 28 - 11:09 AM

--> RV-List message posted by: "JOHN STARN" <jhstarn@verizon.net>

Very long and anecdotal. :-)


Sent from Jack computer - Tom Gummo


do not archive


There has been a lot of talk lately on different props for the RV and Rocket
series aircraft. I have flown with three different props on my plane. I
have been asked to comment on my experiences.


First let me say that I am a pilot (OK, I like to think of myself as a
Fighter Pilot). I would build again in a heartbeat if the money and time
issue would occur again but I don't think of myself as a builder.


Second, I don't have the training of Kevin Horton or the wordsmith skills of
Doug R. but here is my story.


I have the slowest Rocket build with an IO-540 with 250 HP. (Isn't there a
Rocket with the 235 hp version of the engine?). With that said, it PUTS A
GIANT SMILE on my face each time I fly it. I started with a two blade
Hartzell that John Harmon sells for the Rocket. The six verses
four-cylinder engine different can be felt. I total believe the
six-cylinder is smoother.


Here is my flight test experience (note I don't say data). First, I don't
know the max speed at sea level. I just don't fly that way. I takeoff (at
22 GPH), climb to altitude and bring the fuel flow back to a reasonable 10
to 12 GPH and fly around at 140 to 150 Knots indicated. The speeds seen on
my gauges agree with the GPS but not tested in any real manner. At 11,500
or 12,500, the altitudes I go X-country, full throttle, RPM at 2100 or 2200,
fuel flow around 11.5-12.0 GPH, the 140 Knots indicated produced 180 Knots
True.


I let some dumb-guy fly my plane and he had to stop quickly while taxing
back to the hangar and put the plane on it's nose. NEW PROP required.


Enter Jim Ayers; I met Jim several years ago as my EAA chapter helps ACS run
the Copperstate Dash race, which started at APV my home airport. He ran his
RV-3 a couple of times. Turns out that he was building a Rocket too. So we
talked by email helping each other with building problems. By this time, I
knew he was dealer for MT props. So, I gave him a call. Let me say again,
I am a pilot. I didn't want to wait 6 months, 6 weeks, 6 days or even 6
minutes for a new prop. I want to fly. He told me that John Harmon had a
FOUR bladed MT prop he tried on his new HR-III and the Reno Air Races. It
didn't fit John's requirements. John made me a deal and I had a new prop
for my rocket. I knew up front, both Jim and John, told me that, it would
slow me down. As I wanted a military paint scheme (WW-II), the four bladed
prop just looked too good.

(My 250 HP isn't enough to use the prop properly)


The four bladed prop was notability smoother. While it wasn't really
"Turbine like", but except for the noise, it was hard to tell if the engine
was running (he said with tongue in cheek). As predicted, I lost some
speed. The same partial throttle 10 GPH fuel flows, now produce only 140
Knots indicated and at altitude, the GPS is now reporting 170 Knots true.
Sure looks good thou.


I let another dumb-guy fly my plane and as he was putting the plane back
into the hangar, he hit the prop on the hangar door. (Turns out someone
moved the hangar door while he was flying but he didn't check before moving
the plane.) I contacted Jim and we determined that the prop had to be
returned to MT-Germany to fix the ding. He then said something I never
expected. Jim said, "I have a three bladed prop you can use while your prop
is being fixed." Jack and I took off the prop, drove to Jim's house,
returned with the other prop, and was flying the next day.


I couldn't tell the difference in smoothness between the three bladed or
four bladed props. But the 10 knots lost were back.


Here is my summary:


All the MT props were smoother than the Hartzell prop. I don't have all the
model numbers here.


The two bladed Hartzell and three bladed MT produced the best speeds. I
didn't do enough testing to be able to tell if there was any difference.
But it wouldn't be more than one or two knots, so get the one you want.


The four bladed MT prop caused a lost of 10 knots of speed. However, MT
believes that they have a new design and at 250-300 HP ranges, a four bladed
prop will produce the same speeds as the three bladed prop. So far, MT
props have produced what they told me they would so I would like to believe
them. They want another 2200 dollars to change out the new blades for my
old ones so we won't know. 2200 dollars buys lots of gas.


As for Jim, he comes off as a MT dealer because he is. I also believe that
he is willing to help other builders, etc. He sure helped me out this time.
I am sure that he makes money when he gets group buys for MT props, but at
the same time, where are you going to get those prices if you want one. I
for one will give Jim a little slack on his emails.


Tom Gummo

HR-II, N561FS, 240 hours

Apple Valley, CA


P.S. - All those dumb guys were me.


I currently have the new MT 3 blade prop designed for the RV-10/IO-540. Once I get my RV-10 flying, I will post the flight test results. My hanger buddy, and fellow RV-10 builder, has an IO-540 and a two blade Hartzell and when we both have our 10's flying we are going to do a "race test". Won't those results be interesting!!

Regards,

Interesting story on this topic....

At Airventure last year, I was trying to make my prop choice. It came down to a three-bladed MT versus a three-bladed Hartzell. Since Hartzell is in my backyard and a quick drive, I had just always assumed that I'd go with Hartzell.

That was until I talked to the Hartzell cronies manning their display in one of the exhibition halls. When asked for a comparison, all I got was put downs about MT. When I politely tried to re-diect the conversation back to their prop and its performance, all I got was put downs about the MT.

My MT prop is due to arrive any day now.

Yes. One of our local guys installed the 3-bladed MT on his RV-8A. His speeds were down compared to all the other guys around here. He then bought and installed a Whirl Wind 200RV and his speeds came back up. Sorry, I don't have the specific speed increases but he's no longer compaining.

MT vs Hartzell
 

A comment of why performance is down with the MT prop.

First it is known by the "aero guy's" that multi blades interfere with each other and reduce efficiency. THe differnce in efficency is small but speed is not the reason to go with more blades necessarily. I know Jim thinks a 4 blade prop will be the ultimate, but I really don't see 4 blades making much practical sense on a 200hp RV or 270hp Rocket. Planes I flew with multi blades: Ted Smith Aerostar (later PA60) 350hp turbo charged twin 3 blades; 1200hp commuter (Metro Liner) 4 blades.

Why go with multi blades. For one, to absorb high horsepower, requires more blades, but I am talking about 500-1000HP, not 200-250HP. Also, multi blades allows for reduce overall diameter, which improves prop tip ground clearance and lowers tip speeds, which can reduce noise. The big turbo-props (+2000hp) use multi blades (up to 6) with large twist and turn much slower than we do (2000 rpm).

Blade thickness also effects efficiency. Metal blades tend to be thinner than wood or wood core/composite props. Thinner the blade the more efficient.

As far as impact resistance, metal is better and a gouge can be easily blended with a file on the ramp. However wood/composite has vibration dampen qualities that are better. Does that make it smoother? That is debatable. Most of the vibrations we feel are from the engine. A well-balanced metal prop will be fairly smooth. Will a well-balanced composite prop be smoother? Slightly I suppose it could be precieved as smoother but it is a trade off.

Than there is cost: The MT is more expensive and repair is harder to get.

Cheers George

Regarding prop smoothness, impressions of other builders, MT vs. others, such as Hartzell or Whirlwind report a little difference with the MT but not as dramatic as reports of "turbine smooth", but I agree with Penguin-Pete, a composite/wood prop should reduce vibes over a metal blade. I still contend the engine is shaking and the prop is only going to do so much. Builder?s preference. :D

Impact resistance, I agree a metal prop is more likely to damage the crank in an accident, where a wood/composite prop would fragment. However I was referring to more benign rock impacts, which leave a nick in the leading edge. A dent or impact to the leading edge of a MT may cause more damage or damage that requires extensive repair methods than a metal prop blade.

Cost: my first RV had an overhauled Hartzell made from used parts for $2,500. A new one today is around $5,500. You will pay over $2,000, up to $5000 more to get a composite version. Hartzell overhauls go for about $1,500 on a TBO of 2000 hours.

Weight: We are talking about 20lbs average differance in weight between Hartzell and other c/s props with composite blades.

Service life: it is 20,000 hours or 8,700 hours on the original HC-C2YK/F7666 with lightspeed ignition and/or HC pistons. That is a lot of flying. If you flew 200 hours a year that would be over 40 years with electronic ignition. What would a MT wood/composite prop blade would look like in 8,700 hours or 40 years? :confused:

Speed: We are talking about 2-8 mph depending on models (see below).

** The RVator, 1st issue, 2004, pg 5, test of 8 prop's at 8,500', full throt,2500 rpm.

Hartzell C2YR (2 metal blade) = 208.9**
Whirlwind 200RV (2 comp blade) = 206.9
Whirlwind 200C (2 comp blade) = 205.6
Hartzell C2YK (2 metal blade) = 205.4**
Aerocomposite ((2 comp blade) = 204.6
Whrilwind 150 (3 comp blade) = 201.9
MT 12B (3 wood / comp blade) = 200.7**

Metal vs Composite props
 

I would like to offer a different opinion to George concerning vibration. I believe that composite bladed props (wood or glass/carbon) will always result in a smoother engine installation, so would would be loath to fit a Hartzell, although it is cheaper initially. In my opinion the smoothness is worthwhile.

Also, Hatzells are not so tolerant to propstrikes, have finite overhaul lives, and are heavier than MTs (which are heavier than Whirlwind carbon props). Following a prop strike your Hartzell will bend and stop the engine quickly, with the possibility (probability?) of engine damage. Wooden (MT) and composite (Whirlwind) props often break the blades causing less damage to the engine. Result to the prop in all cases is the same (new blades)! There is a good MT service network built up now (although Hartzell is better).

In my opinion the only benefit of a Hartzell is price and may be a couple of mph.

Pete

Props
 

Planning to go Hartzell for my RV-8. It'll have a lycon parallel valve IO-360 with 10:1 pistons. Anybody heard of experience with the Blended Airfoil prop on an engine such as this? Bill

I made the same experience. I have an IO360 with 200 HP on my 8 and cruise maximum 163 kts at 8000 ft with an MT 3-blade. When I asked they told me it depends on the way I build my aeroplane. Other RVs wouldn't have that problem. I still have the propeller but sell the plane in July. My next is a RV7 with an Aero Composite, probably 2 blade.

Stephan

Stephan,

Are you interested in selling you MT prop? If so, I may have an interest in it.

Daryl

Why Aero Composite
 

Why Aero composite. They are crazy expensive. They may be faster than MT but not faster than the Hartzell BA prop. Weight I grant you is better but you should read this guys experience with Aero composite.

http://www.lazy8.net/proptest.htm (click on Aero Composites story)

Not that I think there is anything wrong with Aero Composite, just they are more complicated blades made up of many bonded parts. My big complaint is the size of the company (small), where you can get it overhauled, cost and any blade repair will involve removal from plane and shipping it to the manufacture. The faster composite prop, the RV200 from Whirl Wind, would be an alternative to the Aero composite, but they are having issues with their other models. Although the issues are not with the RV200, the RV200 has a very low TBO. Whirl Wind like Aero Composite, is in the same small company with factory only repair/overhaul boat. Hartzells support can repair or support world wide.

That is why Hartzell has the advantage in every way but weight IMHO. However late model RV's (RV-7/8) can take the extra weight on the nose from a metal prop. I know composites are sexy and an undeniable attraction, but practically speaking $6,000 on a Hartzell BA 7497 bladed prop is hard to beat. Also with the new blade there are no or less restrictions (depending on engine & ignition).