Seems like this 11 blade propeller -- might make a great rear propeller for the Celera 500L:
MT-Propeller 11 blade propeller delivers 15% increase in static thrust
91–100 of 104 posts
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#92Earlier quoted context omitted.
> The hilarious thing is that the government investigation called it a "survivable accident" because no one happened to be seated in the row that it shot through. No, that’s not why. See FAA definition below. Survivable Accident - an accident in which the cockpit and/or structure remains relatively intact and the forces experienced by the occupants did not exceed or should not have exceeded the survivable limits of h…
Trust me, if that propeller had hit someone in the head, they would have experienced forces that would have exceeded the survivable limits of human G-tolerance.
> Such an accident is classified as survivable even if some or all occupants were fatally injured.
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#93I'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…
> The hilarious thing is that the government investigation called it a "survivable accident" because no one happened to be seated in the row that it shot through. No, that’s not why. See FAA definition below. Survivable Accident - an accident in which the cockpit and/or structure remains relatively intact and the forces experienced by the occupants did not exceed or should not have exceeded the survivable limits of h…
In other words, a survivable accident is approximately an accident in which one or more occupants could have theoretically survived, even if in fact they all died. One or more survivors would seem to prove the accident was survivable.
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#94Why are they only using odd numbers of blades?
Generally odd numbers of blades are better for vibration. I know that in wind turbines they are favored because it reduces the effect of the blade crossing the tower. When one of the blades in a three blade wind turbine crosses over the tower the force on it is reduced (since the wind is already slowed by the presence of the tower). The other two blades are in maximum loading, but balance much of their forces against…
On wind turbines there are generally ground drag effects that reduce the wind speed closer to the ground. A 3 bladed setup minimises the wind speed (and therefore thrust) differences between blades, minimizing the off axis forces on the rotor bearings.
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#95Earlier quoted context omitted.
Trust me, if that propeller had hit someone in the head, they would have experienced forces that would have exceeded the survivable limits of human G-tolerance.
> Such an accident is classified as survivable even if some or all occupants were fatally injured.
> occupants did not exceed or should not have exceeded the survivable limits of human G-tolerance
I think it was a joke.
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#96> with an impressive noise and sound signature.
Not sure whether it means that it was loud or quiet. /s
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#97More parts has a cost: the mtbf goes down geometrically.
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#98Earlier quoted context omitted.
With aircraft you can’t just say “efficient” you have to point out what you’re trying to optimize.
In rotor design it's pretty clear. Thrust/power ratio here, or FM (Figure of Merit).
It’s not at all. How much does it weigh? How does it perform at different speeds?
Thrust to weight ratio is very important to aircraft.
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#99I'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…
I agree with what you're saying.
But to add a bit of colour to the incident: the Kori Bustard is the biggest flying bird in Africa, and it's mostly ground dwelling.
Seems like some bad luck was involved too, and I wonder if the same damage will occur with a smaller bird?
Re: MT-Propeller 11 blade propeller delivers 15% increase in static thrust
#100Earlier quoted context omitted.
> That looks like a perfect candidate for 3D printing and then machining the final part vs billet. Now you need two expensive machines, not just one. Billet is not that expensive. I've seen people suggest this before and I looked on their site. They show a multi axis CNC machine making the parts. You would need exactly the same machine to post machine the 3D printed part, but now you have a second expensive and slow…
That makes it a great candidate for near-net casting. That way you save the 80% of tre billet you'd be turning into chips, and your fancy CNC gets more parts per shift.
Alternately, you can do the rough machining on a cheaper 3-axis machine (even outsourcing it).