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

I&#x27;m really not a big &quot;fan&quot; of MT&#x27;s cheezy wooden propellers. They call them &quot;Natural Composite&quot; but it&#x27;s really just densified&#x2F;compressed wood with a thin fiberglass wrapping. Here&#x27;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 &quot;survivable accident&quot; because no one happened to be seated in the row that it shot through. <a href="https:&#x2F;&#x2F;avherald.com&#x2F;h?article=4f2a35e6" rel="nofollow">https:&#x2F;&#x2F;avherald.com&#x2F;h?article=4f2a35e6</a><p>I was involved in the evaluation of proposed repairs to a Beechcraft Bonanza with a 3 bladed MT prop that taxied into a vinyl traffic cone at idle speed. The Beech shed two prop blades, bent the engine mount and firewall. There was a slight cut in the traffic cone, but it was returned directly to revenue service.

Somewhat related thread [0] from last month about the &quot;tipless&quot; Sharrow MX-1 prop [1] which achieves efficiency gains of between 9-15% over comparable 3-blade propeller designs. They started out working on an aircraft propeller but pivoted to a watercraft prop.<p>0: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=33949895" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=33949895</a><p>1: <a href="https:&#x2F;&#x2F;www.mby.com&#x2F;gear&#x2F;sharrow-mx-1-tipless-propeller-110120" rel="nofollow">https:&#x2F;&#x2F;www.mby.com&#x2F;gear&#x2F;sharrow-mx-1-tipless-propeller-1101...</a>

For reference on more or less blades, aviation stack exchange has some great discussions on this subject. One of my favorites<p><a href="https:&#x2F;&#x2F;aviation.stackexchange.com&#x2F;questions&#x2F;23009&#x2F;what-are-the-advantages-of-more-than-4-propeller-blades" rel="nofollow">https:&#x2F;&#x2F;aviation.stackexchange.com&#x2F;questions&#x2F;23009&#x2F;what-are-...</a>

Props with high blade count substantially reduce noise for drones as well<p><a href="https:&#x2F;&#x2F;youtu.be&#x2F;1nk74KEIc2c?t=138s" rel="nofollow">https:&#x2F;&#x2F;youtu.be&#x2F;1nk74KEIc2c?t=138s</a>

As a former aircraft owner, I immediately began to calculate the costs of doing on overhaul on those props. My three bladed props would need an overhaul at least every 2000 hours. There is also a time minimum as well if you don&#x27;t reach the hours before the time interval. It seemed like the engines and the props would hit overhaul hours around the same time, usually hitting me with a bill well over $10,000.<p>I wonder what the cost will be on dual, 11-blade adjustable pitch props? It makes my eyes water and feel thankful I am not the owner&#x2F;operator of such an aircraft.<p>Perhaps it all makes sense given the fuel consumption and speed improvements?

I&#x27;d imagine that, just like in other industries, there are tons of metrics (or counter-metrics) that are also important. Some that come to mind are efficiency, noise, vibration, cost, maintenance, stall characteristics, RPM requirements, weight, etc etc. From some fiddling with RC quads, I remember that increasing the number of blades does increase thrust, but at the cost of efficiency and several other parameters.

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

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&#x27;t the only consideration, but I am curious and I expect there&#x27;s going to be some fan experts in this thread...

Why are they only using odd numbers of blades?

&gt; with an impressive noise and sound signature.<p>Not sure whether it means that it was loud or quiet. &#x2F;s

Seems like this 11 blade propeller -- might make a great rear propeller for the Celera 500L:<p><a href="https:&#x2F;&#x2F;ottoaviation.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;ottoaviation.com&#x2F;</a>

I love how the stroboscopic effects in the video recording makes it look like the blade is spinning slowly like in videogame or anime show airships.

The Wright Bros achieved 90% efficiency with their propellers. Adding 15% to that gives 103.5% efficiency, which I&#x27;m not buying.

Prime number so no harmonics? Therefore no... vampiric eddys or vacuum bubbles...? Just my first guess.<p>How&#x27;s 13? 17?

for those wondering...<p><a href="https:&#x2F;&#x2F;www.reddit.com&#x2F;r&#x2F;AskEngineers&#x2F;comments&#x2F;g39s6s&#x2F;is_there_a_reason_that_fans_always_have_an_odd&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.reddit.com&#x2F;r&#x2F;AskEngineers&#x2F;comments&#x2F;g39s6s&#x2F;is_the...</a>

More parts has a cost: the mtbf goes down geometrically.

What’s the weight?

Ok, how much better is 13 blades?