Constant speed choices ..

A place to discuss different propellers and their pros & cons.
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Spike
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Constant speed choices ..

Post by Spike »

I have recently been pretty much settled on the 2 blade MT for the RV. Though I know of a local flyer who has an Aerocomposites 2 blade on his RV8 and keeps telling me that is the way I should go.

Wicked stick has gone with a 2 blade Aerocomposite prop. I am have yet to figure out why this prop is worth the extra dough. What am I missing?

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cjensen
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Re: Constant speed choices ..

Post by cjensen »

Spike wrote:<snip>What am I missing?

Spike
Uhhh...mmm...the extra dough? :evil: :lol:
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Post by Spike »

I think that gets the award for 'funniest line of the day'. That was great Chad.
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cjensen
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Post by cjensen »

:D :D :wink:
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bullojm1
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Post by bullojm1 »

Spike,

What's your reasoning for going with the MT? From what I have read (and a lot of it is hearsay, so please correct me), but the MT is more expensive than the Hartzel (by a decent amount), it is slower than the Hartzel Blended Airfoil, and it must be sent overseas to get serviced (I can't imagine shipping a 3 blade prop is cheap, especially overseas). I have also read it is smoother because its 3 blade.
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cjensen
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Post by cjensen »

I can make one quick correction...only because we just sent a four blade MT in for overhaul. They can be serviced entirely in the States now at their US distribution facility...still takes 3-6 weeks though... :o
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Spike
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Post by Spike »

bullojm1 wrote:Spike,

What's your reasoning for going with the MT? From what I have read (and a lot of it is hearsay, so please correct me), but the MT is more expensive than the Hartzel (by a decent amount), it is slower than the Hartzel Blended Airfoil, and it must be sent overseas to get serviced (I can't imagine shipping a 3 blade prop is cheap, especially overseas). I have also read it is smoother because its 3 blade.
It is more expensive than the hartzell, approximately $1100. How much faster? Maybe 4 - 5 knots? I can fart and add 4 knots, albeit only briefly. I am not really concerned about a 3% gain in speed, its a 160HP RV9 after all and will smoke all of the Cessna birds that I have been flying. What really brings me to the MT is that it's system weight is significantly lighter than the hartzell, has no rpm / manifold restrictions, and will run smoother being composite.

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captain_john
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Post by captain_john »

Also, what is the TBO for the MT?

I want to say that I have heard it to be something ridiculously low.

I put the MT out of the running a long time ago for some reason. I think it was TBO time?

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Post by Spike »

Are you thinking of the WW props that had factory blade inspections every few hundred hours? As far as I know the MT props are the same time frame as most all other props.
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Post by captain_john »

A quick search of TBO MT Prop turned up several TBO's of 200 hours and 72 months for engines that they have not tested their props with.

That explains alot. I have pretty much only looked at "experimental" lycomings in my research. Besides, I hate German crap. It is usually over-engineered and under-built. Combine that with over-priced and you have a deal-breaker for this kid!

The 72 month TBO (whenever time is mentioned) usually is a corrosion inspection. They all pretty much have that.

So the question is, which engine are you using?

MT might be be good for you?

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Post by Wicked Stick »

There's a 3 bladed MT prop'd Diamond Star (4 seater) at EWB that's been sitting on the ramp for 2 years now. (Owner going through a divorce or who knows what) but anyway, one of the blades on it has delaminated badly down near the hub.

This bird isn't going anywhere soon until it's removed and replaced.

Here was my thinking for a prop choice.
If I had to go fix pitch, hands down it would have been a Catto.
Constant Speed:
Hartzell Blended Airfoil was in the runnning, but I wanted less weight up front for my 8.
Was seriously considering Whirlwind, but at the time they were having spinner back plate issues. (it seems that now they have fixed them)
MT was just as expensive as the Aerocomposites and I too was worried about servicing and shipping so at the time I decided to shell out the dough for my AC prop.
Yes, it's an expensive way to go, but I figured this is probably the last plane I will own and I ain't selling it, so it's kind of my dream airplane to build and fly.

I havn't looked into it, but what is the comparible cost and performance features with Hartzell's new composite props ?
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Post by Spike »

Ill be running a 160HP O-320 not hopped up.

The latest service bulletin for MT dated earlier this year has the 2 bladed version that Van's recommends at 1000hrs / 6 years TBO. The 3 bladed version is 2000hrs / 6 years TBO. I would imagine that they are also raising the times as they get more data from the field. 1000hrs isn't as good as the others so that will have to be weighed against the benefits, of which I see the composite props as having lots. Though if one were to truly pay attention to TBO I am not going to be flying 1000K hours in 6 years of ownership. I doubt that I will be living by TBO recommendations anyway.

Wicked Stick wrote:There's a 3 bladed MT prop'd Diamond Star (4 seater) at EWB that's been sitting on the ramp for 2 years now. (Owner going through a divorce or who knows what) but anyway, one of the blades on it has delaminated badly down near the hub.

This bird isn't going anywhere soon until it's removed and replaced.
Not good. Though we can pull single data points for each manufacturer. I have a local 8 flyer who's new Aerocomposite prop decided to stop changing pitch on a few random flights.
Wicked Stick wrote: If I had to go fix pitch, hands down it would have been a Catto.
Agreed, very much so!
Wicked Stick wrote: Constant Speed:
Hartzell Blended Airfoil was in the runnning, but I wanted less weight up front for my 8.
Was seriously considering Whirlwind, but at the time they were having spinner back plate issues. (it seems that now they have fixed them)
Same reasoning here.
Wicked Stick wrote: MT was just as expensive as the Aerocomposites and I too was worried about servicing and shipping so at the time I decided to shell out the dough for my AC prop.
Ok this got my attention. From what I can tell the Aerocomposites prop is approximately $4K MORE than the MT. Aercomposites lists for $11.5K and Vans has the MT for $7.5K. Does someone have fine print that I am not aware of?
Wicked Stick wrote: Yes, it's an expensive way to go, but I figured this is probably the last plane I will own and I ain't selling it, so it's kind of my dream airplane to build and fly.

Very good reasoning I think :mrgreen:
I havn't looked into it, but what is the comparible cost and performance features with Hartzell's new composite props ?
I can only find evidence that Hartzell is making this prop for the big bore engines, ie. 540's. Vans offers this prop for the 10 at a bit over $15K. *Yipes*
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Post by Bob Barrett »

A few years ago there was a detailed write up in Van's Rvator about the problems and costs they were quoted for repair of a MT Propeller. I think the costs included shipping it back to Germany for repairs. They ended up getting a Hartzell if I recall correctly because it was cheaper and service was more readily available.

I went with fixed pitch Sensich for my RV-6A with an O-320-160hp Lyc and I am thankfull. There are a lot of rocks at the airport and I have been able to sand and/or file the chips out under the supervision of an A&P.

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Post by Wicked Stick »

At the time I bought my Aero prop, the price was 10,500 and I think MT was a little over a 1,000 or so more than the Hartzell.

Do you think the 8 guy at your airport had pitch trouble due to the prop or the govenor ?
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Post by Spike »

It was confirmed that it was the prop. Aerocomposite talked with him that it was because the prop was new and there was still a bit too tight or some such. He has been flying with it recently without problem. It just goes to show that everyone has issues at some point or another.

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