MT prop on io-520?

[Cardiff Kook]

My buddy has a MT on his 185 w an io-520.

The MT is RPM limited at 2700. The 520 makes max horsepower at 2850.


Are people running an MT on a 520 not able to achieve 300hp? Does it make ip for it in some other ways?

Io-550 makes max hp at 2700 hp so it wouldn’t be a limiting factor there

 

[mvivion]

There’s horsepower, which the propeller converts to thrust. What we as pilots really care about is maximum thrust, which may or may not coincide with maximum horsepower.

In the last thirty or so years, propeller manufacturers have done a great job of unlocking potential thrust, with modern propellers producing much better performance in many cases.

But, this is an extremely complex scenario, and max thrust is not easy to measure precisely. Horsepower, on the other hand is easy to measure on a dyno. People talk about static thrust, but that’s one tiny data point, which our aircraft rarely if ever actually experience in real life.

Want info on the MT props? Call McFarlane, and ask to speak to John Nelson. John is the expert on those props, and a great guy.

MTV

 

[hotrod180]

...Want info on the MT props? Call McFarlane, and ask to speak to John Nelson. John is the expert on those props, and a great guy.

McFarlane sells MT props, as does/did Flight Resource which I believe John Nielson owns.
He probably is the authority on MT props.
Dunno if calling McF would work for getting ahold of Nielson, but he posts on the backcountrypilot site.
If he's on board here, maybe he'll speak up.

If you want to put a new prop on your 185, I would suggest a Hartzell Voyager.
If you want a lightweight prop, with all the attendant aspects both good and bad,
scuttlebutt is that Hartzell is working on a composite bladed version.

Personally, for a IO-520 powered C185, I think it's probably pretty hard to beat a McCauley C401.

 

[Dog]

For what its worth my buddy runs a 185 with the voyager 86 inch prop and I have an old school 80 inch Hartzell. Last STOL competition we were both around the 130-140 foot mark in take of distance on all 3 take offs. around If you want some real life numbers. At 86 inches he could benefit from less RPM for better thrust, with the 80 inch you bet y that i am not a single RPM shy of 2850. cheers.

 

[mvivion]

McFarlane sells MT props, as does/did Flight Resource which I believe John Nielson owns.
He probably is the authority on MT props.
Dunno if calling McF would work for getting ahold of Nielson, but he posts on the backcountrypilot site.
If he's on board here, maybe he'll speak up.

If you want to put a new prop on your 185, I would suggest a Hartzell Voyager.
If you want a lightweight prop, with all the attendant aspects both good and bad,
scuttlebutt is that Hartzell is working on a composite bladed version.

Personally, for a IO-520 powered C185, I think it's probably pretty hard to beat a McCauley C401.

McFarlane bought Flight Resource quite a while back. John now represents McFarlane.

MTV

 

[hotrod180]

For what its worth my buddy runs a 185 with the voyager 86 inch prop and I have an old school 80 inch Hartzell. Last STOL competition we were both around the 130-140 foot mark in take of distance on all 3 take offs. around If you want some real life numbers. At 86 inches he could benefit from less RPM for better thrust, with the 80 inch you bet y that i am not a single RPM shy of 2850. cheers.

Per the tip speed calculator on the pponk website

Props - P. Ponk (pponk.com)

an 80" prop at 2850 is making .915 mach-- near the top of the recommended .88-.92 sweet spot.
An 86" prop makes that same .915 mach, but only at 2650 rpm.
An 83" prop at 2700 rpm makes .90 mach.
My own 88" Mac at 2600 rpm makes .919 mach- right at the top of the sweet spot.

 

[OLDCROWE]

Never give up horsepower!

 

[bob turner]

I know nothing about MT props. I only wish I had the skill to get a 180 or 185 airborne in 150 feet.

Here is what happens to MT props when you allow a shop to do your static runup:

 

[TR Dunn]

Never give up horsepower!

Never give up thrust! Horsepower is merely a unit to measure the RATE at which work is done. Thrust is the force which propels an object. A powerplant that is simply developing its full rated horsepower does not linearly equate to thrust. It is how that power is converted to thrust resulting in what we in lay terms call performance that matters. Differing airfoil designs incorporated in the propeller blade result in differing thrust for the same blade velocity just as different airfoil designs in a wing produce differing co-efficient's of lift for the same velocity. Although horsepower is a long-accepted measure of potential performance, in reality it is thrust that we seek in this context. In subsonic flow airfoil design, faster is not always better.

 

[mvivion]

I know nothing about MT props. I only wish I had the skill to get a 180 or 185 airborne in 150 feet.

Here is what happens to MT props when you allow a shop to do your static runup:

Bob,

whatever they ran through that prop would have rendered unairworthy any prop I’ve ever run. Stupid is as stupid does, but it takes something REALLY ugly to significantly ding those metal leading edges.

MTV

 

[OLDCROWE]

Never give up thrust! Horsepower is merely a unit to measure the RATE at which work is done. Thrust is the force which propels an object. A powerplant that is simply developing its full rated horsepower does not linearly equate to thrust. It is how that power is converted to thrust resulting in what we in lay terms call performance that matters. Differing airfoil designs incorporated in the propeller blade result in differing thrust for the same blade velocity just as different airfoil designs in a wing produce differing co-efficient's of lift for the same velocity. Although horsepower is a long-accepted measure of potential performance, in reality it is thrust that we seek in this context. In subsonic flow airfoil design, faster is not always better.

I understand the equation, I just refuse to reduce the given input and expect a better overall outcome with only more efficiency coming from the variable.

 

[peterdillon]

I know nothing about MT props. I only wish I had the skill to get a 180 or 185 airborne in 150 feet.

Here is what happens to MT props when you allow a shop to do your static runup:

Are you sure thats an MT as it doesn't look like any of the ones I had. Also never seen one damaged that close to the hub on a run up.

 

[skywagon8a]

Are you sure that's an MT as it doesn't look like any of the ones I had. Also never seen one damaged that close to the hub on a run up.

That is definitely a wood prop. Notice how the metal tipping goes around the tip and the splintered wood behind the leading edge.

 

[gkm]

My buddy has a MT on his 185 w an io-520.

The MT is RPM limited at 2700. The 520 makes max horsepower at 2850.


Are people running an MT on a 520 not able to achieve 300hp? Does it make ip for it in some other ways?

I have an MT on the 520. It is limited to 2700 RPM. I don't know what I’m missing at 2850 since this prop has never been there. However, prior to the MT, I had a MAC C401. I experimented with 2700 and 2850. Decided that 2700 pulled just fine. 2850 seemed like the plane was stuck in first gear. Good initial pull that lasted for two seconds. After that, turning the prop to 2700 was better. So I started just leaving it set for 2700 with no significant degradation in performance. When I got the MT that was limited to 2700, it wasn’t a bit adjustment.

 

[Supercubrancher]

I have an MT on the 520. It is limited to 2700 RPM. I don't know what I’m missing at 2850 since this prop has never been there. However, prior to the MT, I had a MAC C401. I experimented with 2700 and 2850. Decided that 2700 pulled just fine. 2850 seemed like the plane was stuck in first gear. Good initial pull that lasted for two seconds. After that, turning the prop to 2700 was better. So I started just leaving it set for 2700 with no significant degradation in performance. When I got the MT that was limited to 2700, it wasn’t a bit adjustment.

Two blade or three blade? How noticeable was the weight difference on the nose? That was the biggest difference on the cub with the GA sensenich vs the aluminum prop, large change in cg. Carbon fiber prop is more fun to fly!

 

[gkm]

Two blade or three blade? How noticeable was the weight difference on the nose? That was the biggest difference on the cub with the GA sensenich vs the aluminum prop, large change in cg. Carbon fiber prop is more fun to fly!

Three blade. Weight difference on the nose was 'slightly' noticeable. So much weight goes in the back of the plane that under normal loading conditions, I don't notice. Or at least I don't anymore and have forgotten the initial transition. I exchanged the prop 8 years ago. Plus, I removed the lightweight starter and installed a heavy duty starter. Overall, I definitely lost weight.

HOWEVER, the MOST noticeable difference was the massive change in throttle responsiveness which is useful when getting in slow and short and more importantly, on target. You can throttle jockey it a little like you can a cub on short final to nail a touchdown spot. This was not as easy with the McCauley C401 which is like spooling up a turbofan by comparison.

 

[hotrod180]

...the MOST noticeable difference was the massive change in throttle responsiveness which is useful when getting in slow and short and more importantly, on target. You can throttle jockey it a little like you can a cub on short final to nail a touchdown spot. This was not as easy with the McCauley C401 which is like spooling up a turbofan by comparison.

The responsiveness is the positive aspect of a lightweight prop.
The negative aspect is the lack of flywheel effect when starting, making it more prone to kicking back.
A number of people have blamed starter adapter failures on kickback due to a lightweight prop.
Just something else to consider.

 

[Rob]

Enzo Ferrari was credited with saying "Horse power sells cars, torque wins races". Wonder if he was a pilot?

I'll take torque or the thrust it is converted to over horsepower every single day. And do, on every single take off at work.
YMMV...

As for the triple MT on an IO 520? For the last several years it was the go to on many Pponk conversions. I'd argue that a well built Pponk, isn't giving anything up to a run of the mill IO in power out put, regardless of what the paper says.

Having said all that, it's an older design, and may very well lose its spot as the latest greatest...

Take care, Rob