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MT-Propeller 11 blade propeller delivers 15% increase in static thrust

mt-propeller.com

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Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#51

Post by Hendrikto »

rootusrootus wrote: post #9

Kind of related: Do the same efficiency dynamics that apply to wind turbines apply to a fan providing propulsion? I.e. if a one-bladed fan is the most efficient for capturing wind, would it also be the most efficient airplane propeller or boat propeller? Obviously efficiency isn't the only consideration, but I am curious and I expect there's going to be some fan experts in this thread...

Seems like 1 blade would theoretically be optimal, but due to requiring a counterweight, a two blade design is superior. [0]

[0]: https://aviation.stackexchange.com/questions/23009/what-are-...

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#52

Post by vasco »

WalterBright wrote: post #49

The Wright Bros achieved 90% efficiency with their propellers. Adding 15% to that gives 103.5% efficiency, which I'm not buying.

You don't add them up like this. I can make a car use 50% less fuel an infinite amount of times, not just twice.

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#53

Post by FullyFunctional »

buildsjets wrote: post #46

I'm really not a big "fan" of MT's cheezy wooden propellers. They call them "Natural Composite" but it's really just densified/compressed wood with a thin fiberglass wrapping. Here's an example of what you can expect from in-service damage, a Jetstream 41 recently hit a bird, shed a blade, and it shot right through the passenger cabin. The hilarious thing is that the government investigation called it a "survivable a…

Are the wooden construction essential to the new blade design? What are the Beechcraft Bonanza props made of?

(As a complete layman, not even a pilot, I love the sound profile of the proposed props)

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#54

Post by WalterBright »

vasco wrote: post #52
WalterBright wrote: post #49

The Wright Bros achieved 90% efficiency with their propellers. Adding 15% to that gives 103.5% efficiency, which I'm not buying.

You don't add them up like this. I can make a car use 50% less fuel an infinite amount of times, not just twice.

Please rethink your statement. You cannot get more motive energy than the energy put into the propeller.

> I can make a car use 50% less fuel an infinite amount of times

No, you can't. Conservation of energy applies.

P.S. I didn't "add" them, either. 90% x 115% => 103.5%

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#55

Post by buildsjets »

FullyFunctional wrote: post #53
buildsjets wrote: post #46

I'm really not a big "fan" of MT's cheezy wooden propellers. They call them "Natural Composite" but it's really just densified/compressed wood with a thin fiberglass wrapping. Here's an example of what you can expect from in-service damage, a Jetstream 41 recently hit a bird, shed a blade, and it shot right through the passenger cabin. The hilarious thing is that the government investigation called it a "survivable a…

Are the wooden construction essential to the new blade design? What are the Beechcraft Bonanza props made of? (As a complete layman, not even a pilot, I love the sound profile of the proposed props)

Normally, the prop on a Bonanza is made of aluminum. Based on observation of prior incidents, I would expect no or negligible damage to an aluminum propeller in the same circumstance. However, even if no external damage is seen, some engine manufacturers (and insurers) require a complete engine teardown and inspection in the event the propeller contacts an object while the engine is running.

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#56

Post by [deleted] »

buildsjets wrote: post #46

I'm really not a big "fan" of MT's cheezy wooden propellers. They call them "Natural Composite" but it's really just densified/compressed wood with a thin fiberglass wrapping. Here's an example of what you can expect from in-service damage, a Jetstream 41 recently hit a bird, shed a blade, and it shot right through the passenger cabin. The hilarious thing is that the government investigation called it a "survivable a…

[deleted]

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#57

Post by mcarmichael »

tus666 wrote: post #17

At what point does a prop become a fan? A 777 engine has 22 fan blades, twice this thing.

The relevant conceptual distinction seems to be whether the aerodynamics of the blade(s) are conceptually independent, or interdependent. Better explained here: https://en.wikipedia.org/wiki/Propeller_(aeronautics)#Aircra...

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#59

Post by justsomehnguy »

buildbot wrote: post #30
dmoy wrote: post #23

Earlier quoted context omitted.

> At what point does a prop become a fan? Linguistically, a prop becomes a fan when you anchor it to something immovable, or attach it to something movable but without any intention of propelling it using the prop. Fan - try to move the air around, but not the thing it's attached to. Prop - try to propel the thing it's attached to Edit: I realize that might sound ambiguous given terms like "turboprop" and "turbofan"…

I am not sure this is really correct - turbojets (as in fighter jets) sound more like what you describe, turbofans if I remember correctly, get most of the thrust (>70%?) from bypass air around the combustion, and very little from actual combustion thrust. It just also feeds it's own combustion chamber air to keep the fan part going. Perhaps it is a fan if enclosed? Vs. a prop if not?

>Perhaps it is a fan if enclosed? Vs. a prop if not?

Stipa Caproni

Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust

#60

Post by rbanffy »

vlovich123 wrote: post #29
AmVess wrote: post #28

Earlier quoted context omitted.

The cost of this blade setup means no one will buy it. Very high cost to purchase and equally high cost to maintain for such a tiny benefit. I had a laugh at the noise reduction claim. Sure, it will reduce noise, but the open exhausts on planes are the loudest part unless some nitwit is screwing around with the pitch.

Would that change when using an electric motor?

I'd say the most favorable arrangement for noise would be a pusher configuration, with the engines close to the back of the plane instead of a tractor config on the front. This is done on the Piaggio Avanti. Not sure how well it works, but it looks like a spaceship.

Eviation electrical plane recently changed their pusher design to a tractor, but kept the engines on the back (IIRC, they started with a central big one and two auxiliary ones on the wingtips for use during takeoff).

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