MT Prop experience

Hello all

I am getting close to having to decide on a propeller. I have a 200hp Lycoming and am leaning toward an MT, for weight and smoothness reasons (coolness factor doesn't hurt either ). Does anybody out there run a Lycoming IO-360 angle valve and a MT prop? If so, what do you think of it?

Thanks,
Wade Lively
-8 finishing

Cool yes

RV8RIVETER said:

I have a 200hp Lycoming and am leaning toward an MT, for weight and smoothness reasons (coolness factor doesn't hurt either ). Does anybody out there run a Lycoming IO-360 angle valve and a MT prop? If so, what do you think of it? Thanks, Wade Lively-8 finishing

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Wade if smoothness and coolness is the most important than by all means get a MT prop. I assume your question is based on 3 blade MT and another Brand. Other brands of composite props are the Whirlwind and Aerocomposite.

Smoothness: MT props are smooth because they are made of wood cores. Wood is "God's Composite" and has great damping qualities. The other composites have stiffer cores and construction so they will not be as smooth in general. Metal of course will buzz, but some of the other stiff composite props are no smoother. In fact all Lycomings shake a little and a prop can do only so much. IN the end any wood prop will be smooth regardless of number of blades. If I hear Turbine smooth again about the MT I will scream.


Cost: Hands down winner is the Hartzell and Van's kit is designed around it. The Blended airfoil Hartzell is also the hands down fastest constant speed prop BAR NONE. This was proved in a controlled Fly off Van did a year or so ago (results published in the RVator). Three blades are the worst. The only reason to go three blades is if you have high-speed aircraft (mach +.6) and or 500-2000 shaft HP engine. The multi blades reduce blade loading and slow tip speed, which has a side advantage of less noise. For a 200 hp RV, 2-blades are plenty. Any composite prop is going to be from a small company and service will be harder to get and more expensive. In the case of the MT you may have to send it to Germany to get fixed. The down side of that is shipping and cost. A hartzell can be fixed at hundreds of shops around the country at a cheaper cost. Also remember you MT is made up of many parts bonded (glued) and screwed together (Wood core screwed to metal hub, wrapped in composite and an erosion guard bonded to the leading edge). A rock dent / chip on a hartzell (solid aluminum) can be fixed by you on the plane with a file. The MT with a dent or loose erosion strip might need an expensive vacation to Germany, so you can't afford to go on your vacation. The only down side is I am not sure the blended Hartzell is ready for the IO-360 angle valve 200hp yet. Call Hartzell, that is the one I would get, since it is much faster and cost way less. Even the standard Hartzell HC-C2YK/7666-4 is faster than any of the 3 bladed props by a wide margin and faster than most if not all the 2 bladed composites. The HC-C2YK is cheap and widely available.


Performance & Speed: Look the air does not care what your prop is made of. The fact is the thinner the blade surface the better. Metal Hartzell's have thin airfoils and are as efficient or more than any composite, which tend to need to be thicker due to construction. Again the standard C2YK/7666 is a great prop and available. The blended is the way to go on the 180HP and Hartzell may have the blended airfoil model out for the 200HP now. The Hartzell props where several MPH to +10MPH faster than other props.


Coolness: MT or WW or AC, White, two, three blades cool. To me cool is going faster and with out spending 4 to 5 grand more. The Hartzell can get a fancy custom paint or color as an option. The MT is better here. However at least Hartzell has done the testing to show the fatigue life, which is more than most will fly in a life time, if they stay out of the yellow RPMs.


RPM Restrictions: Yes the HC2YK has a range of RPM?s to avoid. The Hartzell Blended does not have a RPM range limitation. The blended airfoil model does have a single point power or rpm restriction but no range, depending on if you have EI or FADEC. These restrictions do not affect normal operations.


Weight: Nothing new here, the metal Hartzell weighs more. For most RV?s a little weight on the nose is good, especially the RV-7 and guess the RV-8 is the same. My RV-4 has a Hartzell and solo full fuel I was near the front CG, however with passenger plus bag I could load to gross and not exceed the aft CG. A light prop would cause a aft CG problem with passenger and bags.


THE CHOICE
With everything considered performance, maintenance, repair, smoothness and coolness, I would buy a Hartzell. BTW you can have your Hartzell custom painted at the prop shop to match the plane or have wild patterns.

Coolness and Smoothness are your prime interest at loss of performance and at a premium price get a MT. Before you buy a MT ask what shop will do repair and maintenance (warrantee work) and what level of repair can be done. Who pays for shipping. Erosions strips DO come off and can create a lot of shake. I think that that might mean a trip to Germany. Just know what you are getting into before you buy it. Also the props they sell are NOT certified or checked with modified engines. If the dealer says that it has been tested, ask them to show you the STC paper work where that prop was tested, on what engine, airframe and if the engine had modifications (EI, high Comp pistons). The nice thing about hartzell they tested their props on modified engines on RV's. Has MT tested electronic ignition, FADEC,Hi-comp etc... I doubt it. However the fact MT's are made of wood I doubt it has a harmonic fatigue life issue. On the other hand would you feel better with a 20 year old aluminum prop or a 20 year old wood/composite/bonded prop. Chances are both would be fine, but a Hartzell with out corrosion or visable cracks on the surface is eaisier to check.

MT makes a nice product but it is not the state of the art composite construction. No one in aerospace uses wood cores anymore. The down side with the other composite props (WW and AC) is they are stiffer and will not be as smooth. They also still cost a lot and repair shops are few and far between. Infact you may have to send it to the factory for repair, just like a MT would but at least they are in the states. Also you are talking about an experimental prop. The MT is smooth because of the wood core more than the number of blades. May be a suggestion would be go with a 2 blade MT composite/wood prop.

George

Prop weight

gmcjetpilot said:

For most RV?s a little weight on the nose is good, especially the RV-7 and guess the RV-8 is the same.

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The 8 tends to be nose heavy, so we try to keep the nose light, and put batteries in the tail.

Choices

George

Like Mickey said keeping the aircraft in general, and nose in particular, light has a big effect on the ?8 flying qualities. Since I have the ?heavy? engine, I am trying to save weight anywhere possible.

I do not want to get into a propeller debate, since we all have are reasons for each choice on our airplane. I chose the MT for the following reasons.
1) It is 15 lbs lighter.
2) It is smoother to fly behind.
3) It is certified and its design limit is 300hp.
4) It can be fully overhauled and repaired in the U.S.


Yes, it is slower. However Van?s tests did not use the newer blended foil MT. According to other sources the newer MT is about 2-3kts slower. I personally don?t mind trading 2-5kts for smoothness and weight.

Yes, it is more expensive, $2410 more to be exact, quoting Van?s accessory catalog. But, the blended foil from Hartzell is not available for the 200hp and may never be, from my communications with Hartzell.

I am sure the spirit of you post was to be helpful and informative, thank you. But, I have thoroughly thought out and researched every system and choice for my aircraft. Which is why I posted this under the ?8 section, because I would like to hear from pilots with RV-8/A who have 200hp and MT prop.

Thank you,
Wade Lively

MT Prop Experience

Wade,

I can't give you the exact experience that you're looking for, but I do have a little experience with two different props (and airplanes) to share. I have a 180 hp -8 with the older style C2YK Hartzell. I helped a friend build a -7A with a Bart parallel valve 360 with AFP injection, high compression pistons, LSE ignition and the MT 3-blade prop. I've got 100 hours in my plane and about 4 in his. Following are some of my observations.
As far as smoothness goes, there's no comparison. My plane has a definite 'buzz' which I find pretty bothersome. And yes, I've had my prop dynamically balanced. I know all airplanes are different and it might be something in my particular engine/prop/mount combination or the way I built my plane that makes it shakier than others, so take this with a grain of salt. But I know that I'm not alone. You might recall an article by Ken Scott in an RVAtor a year or so ago where he recounted his experiences after mounting a Hartzell on his -6. He was the first person I'd heard who wasn't thrilled with the improvement in performance. He said it was almost completely offset, for him, by the extra vibration, which he also found very uncomfortable.
My buddy's -7A is MUCH smoother and quieter. However, he did have a couple of issues with his prop. First, it was leaking grease from the hup. MT told him to send it to them in Florida, so he flew it down. When he got there, they also found a crack in one blade! Of course, they covered all the repair costs, but it did require a trip to Florida.
As for his opinions on the subject, he loves the looks of his prop but after flying with other RV's he's developed a complex about the speed penalty. He's even made noises about switching to the Hartzell because of that. I told him he's crazy. Again, everybody's different.
Finally, I know with the angle valve engine, you've got to do something to address the CG issue but I'll offer another contrarian opinion here (apologies to Danny). I've got my battery on the firewall and if you look at Dan Checkoway's W&B database, I've got about the nose heaviest -8 out there but I don't find it to be a problem at all. I've heard others say how much better it flies with weight in the rear, but that's not been my experience. I do run out of trim on final when solo and yeah, it doesn't want to three-point, but I find that wheel landings work better anyway both solo and with a passenger so it's not an issue for me.
So, if I had it to do over would I go the MT route? Well, if it weren't for that extra $2,400, I think for me it would be a no-brainer. Even so, I think I would go for it. I don't do a lot of long cross-country's, so the speed penalty isn't as big an issue for me. Plus, you get a completed spinner, so there's less fiberglass work to do.

Jack Fromm
RV-8 QB 81120
Flying 100 hours

Me too

Wade I don't want to get into a debate, and think MT props are great.

Sounds like you have your mind made up, and really want one, great.

Clearly there are advantages and light weight, smoother and no RPM restriction Ops are some of them. I am not sue why everyone is so hot for three blades. The reason for lack of performance is NOT a MT prop thing it is based on physics and aerodynamics of 3 blades vs. 2, for slow (under 300-400 MPH) low HP (under 350-500 HP) aircraft. However the sexy looks have a strong pull. No pun intended.

George

*Pauses momentarily*

How about a McCauley? I think they're about 5 pounds or so lighter than their comparable Hartzell.

Check on installation issues

osxuser said:

*Pauses momentarily*

How about a McCauley? I think they're about 5 pounds or so lighter than their comparable Hartzell.

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It has been done and they look nice but there are issues with spinner and cowl that I have read. Talk to someone who installed a McC. I think the WW uses a McC hub so maybe they have the installation down. Van's cowl and spinner are designed for the Hartzell. McC I do not think has the bolts to mount the spinner. The other issue is cost. McC does not have a OEM deal with Van's and I think cost more. From performance I don't think the McC has any advantage. G

McCauley

osxuser said:

*Pauses momentarily*

How about a McCauley? I think they're about 5 pounds or so lighter than their comparable Hartzell.

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The McCauley is a fine propeller, but unfortuantely it is heavier than the Hartzell. Their 3 blade is 71.3lbs. Their website gives no listing a a CS 2-blade.

Vans prop data, RV-8 MT prop experience

Look here for more info:

http://www.romeolima.com/RV8/Prop.htm

http://www.lazy8.net/proptest.htm
(select MT prop story)

http://www.lazy8.net/acprop.htm

I think you will find it interesting. Several have bought the smooth MT and have been disappointed, especially with the performance.

Vans Prop results (Ref. 1) from Randy's data and their data combined:

Hartzell C2YR-1BF/F7496.........208.9 (metal)
Whirlwind 200RV....................206.9
Whirlwind 200c.....................205.6
Hartzell C2YK-1BF/F7666A-4..205.4 (metal)
Aeocomposites...................204.6
Whirlwind Series 150...........201.9 (3 blade)
MT MRV12B/183-59............200.7 (3 blade)

Fastest prop METAL two Bladed F7496 Hartzell
Slowest 3 Bladed MT composite/wood (by 8.2 MPH slower)
Least expensive prop Hartzell C2YK & C2YR
Most expensive Aerocomposite (I think?)

**Ref 1- 1st issue 2004 page 5, Richard Van Grunsven (two RV's where used and the base speed difference was about 14 MPH. RV-8's where Van's proto and Randy RV-8.com)

Just so people reading this don't get confused, there's a big difference between the smoothness that a MT prop provides between a 4-banger and a 6-banger. There is less of a "thumping" issue on the 320/360 engines. There's a bad thump on the 540's with a two-bladed Hartzell right at 2200 RPM. The MT is about 2 MPH slower on the Rocket than the two-bladed Hartzell and without that nasty/annoying thump. So when you're discussing performance related to the RV10 (and Rockets), which is how this thread started, it's pointless to mix in performance data on the other line of RVs. It doesn't apply.

I have not heard of anyone using a ground adjustable prop on an RV- is there a reason why?

Most of the newer gyroplanes around use ground adjustable props and have approx the same engine HP/torque as the RVs.

What?

f1rocket said:

Just so people reading this don't get confused, there's a big difference between the smoothness that a MT prop provides between a 4-banger and a 6-banger. There is less of a "thumping" issue on the 320/360 engines. There's a bad thump on the 540's with a two-bladed Hartzell right at 2200 RPM. The MT is about 2 MPH slower on the Rocket than the two-bladed Hartzell and without that nasty/annoying thump. So when you're discussing performance related to the RV10 (and Rockets), which is how this thread started, it's pointless to mix in performance data on the other line of RVs. It doesn't apply.

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Let's not get confused we are talking about RV's and the three blade MT is about 8 MPH slower. Your 2 mph is great but how did you get that? I also don't buy Van's test only applies to the RV-8.

Here is what another Rocketeer reported:

N395V wrote: MT 3 blade - I am flying behind an IO540 with an MT 3 blade. Started bwith a 2 blade Hartzell [SNIP] Performance cost was approx 5 Knot decrease, 300' increase in takeoff distance and 200-300fpm decrease in climb.

As far as " Pointless to mix in performance data of the other lines of RV's", that makes little sense. I can tell you the 8 MPH on the RV-8 is going to be about the same on a RV-4, RV-6, RV-7, RV-8 and RV-9. HP and speed are factors as I explained, but these planes are fairly matched. There is no major aerodynamic reason that the performance of the same prop would be much better or worse on one model vs. another airframe. I have no idea what physics would cause this. Yes there is a differnce between a 160HP RV-9 and a 200 HP RV-8, but the 200HP RV-8's have shown a loss of about 5-7kts. The slower and lower HP the airplane the less efficent 3 blades are. I stand to be corrected. For High HP and speed aircraft like a C-130 (2500 HP per) 4 blades makes sense.

As far as Rockets, I know you are proud of your plane, being only 2 mph slower with a MT 3 blade'er; I remember you stated that your Rocket gets better gas mileage than RV's with smaller engines, so you Rocket seems to be better than other planes and may not represent an average RV or Rocket.

The laws of physics and prop theory apply the same regardless of what airframe it is bolted to. I agree the disadvantage of a three bladed MT might be less with the higher HP and aircraft speed. Again how did you figure that?

The Rocket is faster and has higher HP and makes better use of 3-blades than on a stock RV. However the speed differential you state (2mph) does not mean anything, unless you tell us how you got it. No offense to your estimation in speed but you don?t state your test method, so it means very little. It is like saying Turbine smooth.

One thing I learned is people seem to get defensive when you say their prop has a speed dis-advantage, and feel a need to defend the choice. I never said the MT prop is bad or not smooth, but I am encumbered by the facts. I am more likely to put more weight behind a well documented test by Van's Aircraft than one or two individuals estimate on one aircraft, and I don't buy it applies to a RV-8 only.

NOT SAYING any one is wrong, but there has to been some scientific approach and documentation to make it a valid data point. If three blades are good what about 4! Well someone tried a 4 blade MT on their Rocket I recall, and it was 8-10 MPH slower. Of course this is anadotical and have no data, but it goes to show you the need for controlled conditions in flight test.


The research on props has done over the last several decades is pretty clear. The trend to multi blades on small general aviation piston planes are for some good and some dubious reasons, as well as personal reasons (looks cool), but there are trade offs, which are OK. However we can't have our cake and eat it to. Aircraft design is made up of many trade-offs. For the 540 cu-in engine the MT may be a good choice because:
A) you have so much excess performance you can stand a loss of a few kts (OR)
B) You have a RV-10 and comfort is important (smoothness/noise). Of course some put the MT on for the sexy looks, which is also OK. Peace.

For the RV's two blades, in my opinion is the "Best Buy". Further the Hartzell is the best Value. For Rockets and RV-10's where performance is not critical (because you have more than enough or it is not as important as other factors), 2 or 3 are fine.If you have the money and are not worried about service of the prop the MT is a great choice. I would avoid 4 bladed MT props because the speed loss is too great. I think the 4 bladed MT is STCed for the Ted Smith/Piper Aerostar, 350 HP turbocharged twin. I used to fly checks in one and there stock prop is a three blade prop.

George ATP, CFI, MSME, RV-4/7/B757/767

ground clearance

is there anyone out there that thinks a three blade offers more ground clearance?

In 2001 IIRC, I was standing with Van at Flabob after he landed in the RV-9a as our guest of honor-- and I mentioned that with the MT three-blade prop, well you have some more ground clearance.... one of his eyebrows went up, I got enlightened,

no extra ground clearance just because it looks like it.

ground clearance

I guess it depends on the prop length. If the blades on a 3 blade prop are the same length as the blades on a 2 blade prop, then the ground clearance will be the same. If the blades on the 3 blade are shorter, which they normally are for a given application, then there will be more ground clearance.

f1rocket said:

Just so people reading this don't get confused, there's a big difference between the smoothness that a MT prop provides between a 4-banger and a 6-banger. There is less of a "thumping" issue on the 320/360 engines. There's a bad thump on the 540's with a two-bladed Hartzell right at 2200 RPM. The MT is about 2 MPH slower on the Rocket than the two-bladed Hartzell and without that nasty/annoying thump. So when you're discussing performance related to the RV10 (and Rockets), which is how this thread started, it's pointless to mix in performance data on the other line of RVs. It doesn't apply.

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I actually posted this in this forum by accident. It was intended for the RV-10 forum, where a similiar discussion is taking place.

The 4-banger performance data is most appropriate for this forum, so I apologize for posting in the wrong one. I was trying to figure out where my post went!

George, regarding some of your comments, I'll only say that the performance data for the Rockets was taken from a flight test performed by a fellow Rocket builder under controlled circumstances. It applies to the RV-10 but not here.

I'm glad you like your Hartzell.

BTW, you don't need to sign your post with your resume. I bow to your obvious superior intellect on all things aviation related, as noted by your over 500 posts since January. You obviously have a lot of experience to share with everyone.

Thanks

f1rocket said:

BTW, you don't need to sign your post with your resume. I bow to your obvious superior intellect on all things aviation related, as noted by your over 500 posts since January. You obviously have a lot of experience to share with everyone.

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I detect a little sarcasm. I can sincerely say I bow to your excellent workmanship of your Rocket, I have seen your site and workmanship, very nice. My pet peeve is accurate data and info. There is something to the IO540 HP and performance. Also there is some claim that speed difference (2 vs. 3 blade) becomes nil at high altitudes. It would be interesting to research this. One individual tried but the data is too inconsistent and scattered to be of use. Vans test was done at one altitude. Although 8,000 is a practical nominal altitude, performance at higher altitudes would make sense for the higher HP Rocket and RV-10. Glad you like your MT prop. Cheers George

George,
Speed is not everything, but it is one of the characteristics to consider. I do have a question for you though concerning fixed props.

Wouldn't a 3 blade "cruise" prop be a better choice for an overpowered RV (thinking 180-200 HP in an RV-9) to allow a faster climb rate?

Prop to derate?

cobra said:

George,
Speed is not everything, but it is one of the characteristics to consider. I do have a question for you though concerning fixed props.

Wouldn't a 3 blade "cruise" prop be a better choice for an overpowered RV (thinking 180-200 HP in an RV-9) to allow a faster climb rate?

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I totally get your point, but the MT prop in all fairness is not that much slower to "de-rate" the speed that much to account for 20-40 HP.

Your example of a 180-200 HP RV-9, I would say I am totally against, regardless of prop. Van designed the RV-9 for 160 HP (I)O-320 and I have much respect for Van and Van's Aircraft. My personal opinion is to stay close to the recommended engine for a given model.

I agree speed is not everything. People love the MT for the smoothness and looks. Hey some like German engineering. I want a Porsche 911. I have had cars that are better in so many ways to the 911, but I love the older 911's, even though it requires more expensive maintenance. I also have my eye on a BMW aircooled "boxer" motorcycle. Technically there may be better motorcycle engines (more power, smoother), but I love the BMW motorcycle. I totally get it. If you want a MT prop get one, but do it knowing that it may cost more to own. It is like buying a 911 and thinking it will be as relaible and cheap to maintain as an Acura or Lexus.

G

I think John Harmon said his 3 blade MT that he tested was faster at redline at altitude. Slower at most all other settings-- compared to Hartzells.

Interesting

mark manda said:

I think John Harmon said his 3 blade MT that he tested was faster at redline at altitude. Slower at most all other settings-- compared to Hartzells.

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I think there is something to that. I don't have my prop design ref's handy, but I think there is some engineering basis for that claim as well. I would only say most pilots don't fly real high at red line all the time, some do. So for those who may want to fly real high and cruise the speed disadvantage apparently is less, which is cool. I have heard that now 2 or 3 times. Now it would be interesting to document that. This is what these forums are all about. Getting good data not bashing. Thanks Mark for the info. G