RV-7 Constant speed Hartzell vs MT?

[JPalese]

What are the merits of the constant speed Hartzell vs the MT on an O-360 equipped RV-7?

In the Hartzell line would you use the metal or composite prop?

In the MT line, 2 or 3 blades?

 

[Andy Hill]

There is no right / wrong... If you have answers to the following it may help you decide and/or give advice?

1. Weight Priority [Composite] (include CG aspects v RV-7)
2. Cost Priority [Hartzell BA]
3. Rock solid reliability / durability [Hartzell, metal]
4. Climb Perf [3 blade / Hartzell 7605] v Top Speed Perf [2 blade / Hartzell BA]
5. Low vibration [Composite]
6. Looks [personal choice, but tends to bias to 3 blade]
7. Supplied v builder finished Spinner [MT]
8. Ease of Cowl removal/refitting [2 blade]
9. Will RV be kept in a cramped hangar? [2 blade]

I am sure someone will come along to advocate the Whirlwind props as well... not an (easy) option for us over here since not certified.

 

[Kahuna]

I think Andy made a very good list. Id add.

Service and Support. (Hartzell)
Supporting YOU. (Hartzell). Hartzell supports many activities that you are interested in. This site, RV teams etc. All things being equal, you should support those businesses that support the causes you appreciate and take advantage of.

 

[JPalese]

Hartzell BA Metal or Composite

Mike:

I appreciate the addition to Andy's list.

On an RV-7 with an O-360 would you use the metal or composite Hartzell?

Does the composite Hartzell have the same restricted RPM operating range of the metal prop.

Both the metal and composite props are blended airfoil, correct?

Thanks!

 

[Kahuna]

Mike:

I appreciate the addition to Andy's list.

On an RV-7 with an O-360 would you use the metal or composite Hartzell?

Does the composite Hartzell have the same restricted RPM operating range of the metal prop.

Both the metal and composite props are blended airfoil, correct?

Thanks!

There are not any RPM restrictions on either of these for your configuration that Im aware.
The choice between metal and composite for Hartzell comes down to a tradeoff in performance and price and a couple of other things.
The metal prop is heavier and life limited.
The composite is lighter and unlimited service life. Lighter provides a host of performance advantages air born. It also has more static thrust which lends itself to additional performance advantages like take off distances and the like.
The composite is smoother by a lot.
Cruise and top end are equal within a knot or 2 across our fleet.
So if you pay the premium for composite, you get weight savings, smoothness, static thrust, and service life. If none of those appeal to you, then the metal is less expensive while still providing excellent performance.

 

[gereed75]

I'll add one additional emphasis - CG concerns.

Tailwheel 7's (and 6's) can tend toward aft CG, especially with lighter (composite) props.

Aft CG's (even within the allowable range) will effect control feel and response (particularly in landing), exasperate the bounce tendency, and limit weight hauling capacity.

It is possible to get the empty weight CG forward in the range (where you want it) in a 7 with a light prop, but you need to plan for it in the build (prop extension, everything placed forward that you can etc.).

I originally had an RV 200 in my 6 with a resultant more aft than average empty weight CG. Loved the prop but definately felt the issues when CG's shifted aft (low fuel, two aboard, any baggage). After considering many options, I switched to Hartzell BA.

It is a much happier airplane with a more forward CG. The nose feels more "stable" and I like the more balanced control response. Way less tendency to bounce during landings. Less weight on tailwheel during taxi. Full baggage capacity.

As far as the other issues - Vibration is about the same (in my case the Hartzell "feels" smoother, but neither prop was dynamically balanced). Engine response is more damped with Hartzell (kinda like a four stroke compared to a two stroke). Airplane is about 1.5 KIAS slower with Hartzell. Can't discern a climb difference. Don't do a ton of acro so can't make a direct comparo there like Kahuna can, but for gentlemen acro it is fine.

These effects are a combined function of prop difference and also a CG shift.

Best of both worlds?? - a slightly faster composite prop with an overall lighter airplane and a forward empty weight CG. It can be done but you gotta plan for it.

By the way, RV-200 (250 hours) available at a good price!! See the Classified FS thread.

 

[JPalese]

More questions

I agree with Kahuna about supporting RV friendly sponsors when possible.

Here are some more questions:

1) I did not find the weight difference between the 72" BA Hartzell metal and composite props listed on either the Vans or Hartzell web sites. Anyone know?

1a) It also appears that while the Hartzell Composite is made in both 72" and 74" inches, the only model sold through Vans is 74". Is that correct? Is a 74" diameter prop too large for an RV-7?

2) Never having flown behind a composite prop, what is (are) the payback(s) for the considerable extra up-front cost? . . . . According to Kahuna, "So if you pay the premium for composite, you get weight savings, smoothness, static thrust, and service life. If none of those appeal to you, then the metal is less expensive while still providing excellent performance."

Can the longer service life of a composite prop vice the metal prop be translated into dollars and cents?

2a) Any downside(s) to composite vs metal props? Is a composite prop more easily damaged by FOD (sand, and debris) during ground operation? Can the composite prop be field repaired by filing like a metal prop?

3) According to Vans, an MT Governor can control a Hartzell Prop and vice versa. Anyone have any words of wisdom on the MT vs Hartzell prop governors?

4) What can be done during construction to offset the lighter weight of a composite prop so as not to adversely affect CG and load carrying capacity?

Anything I did not ask, but should have?

Thanks guys!!

 

[JPalese]

More questions

I agree with Kahuna about supporting RV friendly sponsors when possible.

Here are some more questions:

1) I did not find the weight difference between the 72" BA Hartzell metal and composite props listed on either the Vans or Hartzell web sites. Anyone know?

1a) It also appears that while the Hartzell Composite is made in both 72" and 74" inches, the only model sold through Vans is 74". Is that correct? Is a 74" diameter prop too large for an RV-7?

2) Never having flown behind a composite prop, what is (are) the payback(s) for the considerable extra up-front cost?

2a) Any downside(s) to composite vs metal props?

3) According to Vans, an MT Governor can control a Hartzell Prop and vice versa. Anyone have any words of wisdom on the MT vs Hartzell prop governors?

4) What can be done during construction to offset the lighter weight of a composite prop so as not to adversely affect CG and load carrying capacity?

Anything I did not ask, but should have?

Thanks guys!!

 

[Kahuna]

I agree with Kahuna about supporting RV friendly sponsors when possible.

Here are some more questions:

1) I did not find the weight difference between the 72" BA Hartzell metal and composite props listed on either the Vans or Hartzell web sites. Anyone know?

1a) It also appears that while the Hartzell Composite is made in both 72" and 74" inches, the only model sold through Vans is 74". Is that correct? Is a 74" diameter prop too large for an RV-7?

2) Never having flown behind a composite prop, what is (are) the payback(s) for the considerable extra up-front cost? . . . . According to Kahuna, "So if you pay the premium for composite, you get weight savings, smoothness, static thrust, and service life. If none of those appeal to you, then the metal is less expensive while still providing excellent performance."

Can the longer service life of a composite prop vice the metal prop be translated into dollars and cents?

2a) Any downside(s) to composite vs metal props? Is a composite prop more easily damaged by FOD (sand, and debris) during ground operation? Can the composite prop be field repaired by filing like a metal prop?

3) According to Vans, an MT Governor can control a Hartzell Prop and vice versa. Anyone have any words of wisdom on the MT vs Hartzell prop governors?

4) What can be done during construction to offset the lighter weight of a composite prop so as not to adversely affect CG and load carrying capacity?

Anything I did not ask, but should have?

Thanks guys!!

I can answer a few of those.
1a. We chose at Hartzell recommendation the 76" for all of our fleet with the exception of the RV-4, where we chose, at our decision not Hartzells, the 74" since we have a short legged R-4. We don't have a 7, but our RV6 is running 76". Heck I run 80" on my 8. No problem.
2a. Our experience is that the nickel edge of the composite prop is much more capable of maintaining its edge than its aluminum counterpart. So from a wear and nick point of view, composite prop wins. And as for repair, again the composite wins hands down. Certified unlimited service life is all about no(or perhaps very tiny) material fatigue and serviceability of the leading edge and composite materials. You would be shocked at the amount of damage a composite blade can withstand and still be repairable by Hartzell. Ive seen some in their plant. Its quite amazing.
3. We found both those governors and others, functioned the same.
4. Not unlike what you see in weight build distribution of other RV's, the battery is the easiest move up to the FW. There are of course other options as well.

Ill see if I cant get the weight diff #'s on the 2 props for you and report back.

 

[Kahuna]

I agree with Kahuna about supporting RV friendly sponsors when possible.

Here are some more questions:

1) I did not find the weight difference between the 72" BA Hartzell metal and composite props listed on either the Vans or Hartzell web sites. Anyone know?


Thanks guys!!

And from Hartzell....

The metal C2YR-1BFP/F7497 weight is 58 lbs (prop only, no spinner)

The composite C2YR-1N/N7605-2 weight is 41 lbs (prop only, no spinner)

 

[Kahuna]

Correction... Our prop lengths are 76" on all our RV-8's and our single RV-6, but our RV-4 is a 74". Hartzell offers 76", 74", and 72". Im not sure why the 76" is not being offered on Vans, but I suspect you could certainly ordered the 76". It was the 76" that was the recommended length for our planes. I correct my earlier posts so there is no confusion. Sorry about that. Record now corrected.

 

[gereed75]

Agree with everything Kahuna said.

Disregarding the repair factors, the service life for a Hartzell aluminum prop is at least 8000 hours. You are not likely to get there so that part of the equation is mute.

If I were building again, my choice would be a composite prop, (probably Hartzell), 74" (I'll take the 1" more ground clearance vs 76") with a prop extension to put the lighter prop on a longer weight arm to negate the CG concerns.

The prop extension also gives you the advantage of an extended cowl for better cooling air flow.

Check Hydroguy's 7 for what I think is the optimum four cylinder set up. All IMHO of course.

 

[hydroguy2]

Check Hydroguy's 7 for what I think is the optimum four cylinder set up. All IMHO of course.

Thanks Gary...I don't know if it's optimum, but seems to work for me.
The WW200RV prop is 38# with the carbon spinner so I used a Saber 2.25" extension. I also tried to mount everything(ELT, Strobe pak, etc) forward if possible. My -7 weighed under 1100# completed and CG is never an issue.

Saber makes a nice product, highly recommended for a light composite prop on a light parallel valve engine.

 

[Capflyer]

What are the merits of the constant speed Hartzell vs the MT on an O-360 equipped RV-7?

In the Hartzell line would you use the metal or composite prop?

In the MT line, 2 or 3 blades?

The difference can be summed up in one word: Ethics

The decision between these two is very simple. You will come to your own conclusion if you go back and read through many of the problems MT props have had and poor customer service. Do a search for MTV-15 which is their CS metal 2 blade prop. The guy that purchased my RV7 four years ago was just told he needs to replace the entire prop after only 427hrs TT. The MT governor is fine, no issues with that.

True story....when my MT prop on my RV7 with less than 100 hrs on it was spitting grease all over the plane I had to fight with MT in Germany to cover the repair to re-seal the blade shafts in the hub which in essence is a rebuild. They initially told the shop they would not cover the removal and reinstallation of the prop and that they would have to rebuild it while it was on the plane. Nay nay I said and had to continue the fight with them with the MT authorized shop's support......and that was only the first time. The second time was even more of a battle.

I love the Hartzel on my RV4.

 

[dmeloche]

I have a MTv-11 on a 160hp RV6. I generally like the propeller, it is light and has smooth operation. However it has a recommended overhaul at 72 months or 1000 hrs whichever comes first. The OH cost starts at $2100 and goes up from there.
After about 50 hrs of operation it started throwing grease. It was still under warranty so they repaired (after dealing with Germany) it but I had to remove it and deliver it to a authorized service center. A friend of mine had the same problem, his was outside of warranty by about 6 weeks and they wouldn't cover it. He had to pay to have it repaired. Not good customer service.
The comments about aft CG issues are correct. The airplane becomes a handful on landing when low on fuel with 2 souls and some luggage aboard. If I had to do it again I would take the 20lb weight hit and go with the Hartzell

Doug M
RV6 570hrs

 

[N941WR]

Great tread for those of us who are researching CS props.

Can I toss in WW props into the mix? How do they compare to the other two?

[ed.] No Please. Let this man have his thread.

 

[Russ McCutcheon]

The difference can be summed up in one word: Ethics

The decision between these two is very simple. You will come to your own conclusion if you go back and read through many of the problems MT props have had and poor customer service. Do a search for MTV-15 which is their CS metal 2 blade prop. The guy that purchased my RV7 four years ago was just told he needs to replace the entire prop after only 427hrs TT. The MT governor is fine, no issues with that.

True story....when my MT prop on my RV7 with less than 100 hrs on it was spitting grease all over the plane I had to fight with MT in Germany to cover the repair to re-seal the blade shafts in the hub which in essence is a rebuild. They initially told the shop they would not cover the removal and reinstallation of the prop and that they would have to rebuild it while it was on the plane. Nay nay I said and had to continue the fight with them with the MT authorized shop's support......and that was only the first time. The second time was even more of a battle.

I love the Hartzel on my RV4.

Just a couple of point, the MTV-15 has been around for a long time most have composite blades like my MTV-15B-183-33, only in recent years has MT been putting metal blades on this prop, another thread suggests there are only 48 units out there with metal blades and yes I would avoid those.

I’ve had the good fortune of buying my MT prop on an old flying airplane where the prop is well out of any warrantee, I found a great shop (http://www.nwpropeller.com/) and have about 1300 hours on the prop now since I’ve owned it, it has leaked grease but it has also gone about 1000 hours in a stretch without leaking grease, I like the prop a lot, I have overhauled it twice now, once just after buying the airplane and once a year or so ago, MT USA has done the blades both times and done a good job, NWProp has done a good job and has stood behind their work, they had to reseal it after the last O/H, they came and got the prop and they brought it back. MT in Germany has been great a bought answering e-mail questions I have had over the years but I never had to ask them to pay for anything. All the brands have had problems with grease leaks, I don’t know if MT is worse or not but it may be. All that said I find myself wanting the new Hartzell Composite prop at my next O/H time, it’s a lot of money though.

 

[Bavafa]

Thanks Gary...I don't know if it's optimum, but seems to work for me.
The WW200RV prop is 38# with the carbon spinner so I used a Saber 2.25" extension. I also tried to mount everything(ELT, Strobe pak, etc) forward if possible. My -7 weighed under 1100# completed and CG is never an issue.

Saber makes a nice product, highly recommended for a light composite prop on a light parallel valve engine.

Does the prop extension effect your max G ?

When I was researching during my build, I was told that the G force limit will be lowered and not safe for any aerobatics with a 2.5" prop extension.

 

[hydroguy2]

Does the prop extension effect your max G ?

When I was researching during my build, I was told that the G force limit will be lowered and not safe for any aerobatics with a 2.5" prop extension.

I don't know. It has never affected my "G", but in full disclosure, I've only rolled my plane a few times. I've never pulled more then 3 Gs.

 

[Lindamon]

MT's are great in my experience

I have flown Unlimited aerobatics with MT's, both on my 230 and 300L, and never had a problem. Gerd is often at the Sebring contest, and is very forthcoming, I have never heard any of the complaints I see here from anyone in the aerobatic community, and MT's are probably the most common prop there. But I admit it's totally anecdotal evidence, and everyone can have differing experiences.

I put an MTV-9 three blade on my -7, it has counter-weights and a aerobatic governor. I will report if I have any problems.

 

[mikempp]

getting off the subject, how big a difference in speed, climb rate, fuel economy and sound between fixed pitch and constant speed. Sure love cruising in my 210 at 2,200 rpm, couldn't imagine it being as nice at 2,500.