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I fly a large 4-engine turboprop. It uses constant speed hydraulic props, which automatically change blade angle to maintain 1020 rpm. The sync box (which I was unable to find a picture of) takes inputs from each engine's tachometer generator (where it gets the RPM signal) and a pulse generator, which is a magnetic pickup right behind the prop. There is a ...


3

As a rule of thumb, use fully turbulent flow at the elevated speed of the propeller wake on all surfaces wetted by it. The speed increase will result in higher friction drag compared to the propeller-free case and results in a drag increase that looks about right. A very interesting paper on the efficiency of an installed propeller can be found here. By ...


3

According to this ATSB Australia Report, the Original Blade Weight of the Trent 800 Blade that failed was 11.6KG. The weight of the blade in grammes is etched into the blade root. https://www.atsb.gov.au/media/33974/tr200100445_001.pdf Page 9/10. Fan Blades of the same type all differ (slightly) in weight and are chosen specially to balance the engine when ...


3

I have seen the movie, but it failed to occupy my memory... anyway: Yes, the A400M propellers are contra rotating, and more specifically DBE as you described. I am not 100% sure, but I'm willing to bet all A400M's ever produced have this configuration. So if the propellers seem to rotate in the "wrong direction" there are two possible causes: it ...


2

There are some aircraft that indeed have just power lever and set the RPM on schedule, e.g. the Pilatus PC-7, PC-9, PC-21 line of trainers. Since they are primarily designed for training future jet pilots, and jet aircraft only have power levers, it makes sense to skip the complexity of separate propeller and condition controls. However normally there are ...


1

Yes, the same propeller can be used. Propeller thrust is proportional to air density. The same is true for aerodynamic drag, so your propeller will work at all altitudes equally well. Since the speed of sound drops with temperature, you need to pick your propeller tip speed for the coldest layer, which normally is the Tropopause. There, the speed of sound is ...


1

I can't offer the technical backup, but years ago, I read that if the props are designed to run at slightly different rpms, it reduces the otherwise-hellacious sound produced by the contra props. Noise has been an issue with these since engineers started using them (late WWII I think). Of course, none of the NK-12 powered aircraft are known to be "...


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