Foreign Turboweenie Porn

[C420sailor]

Remember that the tip is also moving forward through the air. I don't feel like doing the math.

I doubt that'll add much...?

 

[mmx1]

so if Vt = stationary tip velocity (263m/s at redline), and
Va= velocity of the aircraft
Vmoving = sqrt(Vt^2 + Va^2)

Which at 190 knots bumps the tip velocity up to 280m/s

 

[usmarinemike]

Pretty much anybody can look at a turboprop and know that it gets negligible thrust from the exhaust. Compared to a Pilatus or a King Air (both sporting PT6A variants, btw) the T34 has so much more prop noise than turbine noise. Any SWAGs on why?

 

[FlyingOnFumes]

Pretty much anybody can look at a turboprop and know that it gets negligible thrust from the exhaust. Compared to a Pilatus or a King Air (both sporting PT6A variants, btw) the T34 has so much more prop noise than turbine noise. Any SWAGs on why?

PT6A is not a single model, but a family of powerplants. Some more powerful than others (just look at T-6 A/B vs. T-34C for instance). Could this have any impact?

 

[C420sailor]

PT6A is not a single model, but a family of powerplants. Some more powerful than others (just look at T-6 A/B vs. T-34C for instance). Could this have any impact?

Also, different prop designs.

 

[nittany03]

I doubt that'll add much...?

I'm more depressed that, 5 years later, I remembered that a T-34 prop turned at 2200rpm without looking it up. I'd go on about what a nerd I am, but it's not like that was a surprise or anything . . .

 

[Beans]

Pretty much anybody can look at a turboprop and know that it gets negligible thrust from the exhaust. Compared to a Pilatus or a King Air (both sporting PT6A variants, btw) the T34 has so much more prop noise than turbine noise. Any SWAGs on why?

I don't know anything about the ducting of intake air in a King Air or Pilatus. Can someone who knows those aircraft weigh in? Is it a siren-like whine? Or is it more of a high-pitched whooshing like you get from a small turbojet?

I know for the T-34, any noise coming from rotor/stator interaction at the intake or exhaust is probably (and I'm admittedly guessing) attenuated pretty well because the intake and exhaust flow has so many curves and turns to get around. I do remember a little whine here or there, but most of the time it was pretty quiet.

Oh yeah, and wrt the 263m/s tip speed (or 280m/s at 190kts)... so that's around M=.76. Certainly in the compressible range, but not necessarily transonic... I dunno. It's still the noisiest part of the aircraft.

 

[porw0004]

Any insight into why beta sounds so different?

Btw I haven't gotten my + rep yet... just sayin'... :icon_smil

 

[C420sailor]

Any insight into why beta sounds so different?

Btw I haven't gotten my + rep yet... just sayin'... :icon_smil

My SWAG would be that it has something to do with a positively cambered airfoil (prop) with a negative AOA (full beta at -5*)? More turbulent flow as a result?

I love that sound.

 

[MIDNJAC]

so if Vt = stationary tip velocity (263m/s at redline), and
Va= velocity of the aircraft
Vmoving = sqrt(Vt^2 + Va^2)

Which at 190 knots bumps the tip velocity up to 280m/s

So I think the question we are all really wondering the answer to is: does it still take off if its on a treadmill shrek?

 

[MIDNJAC]

I love that sound.

You should hear an E-2

 

[MasterBates]

An E-2 in full reverse as heard from the LSO shack.. Is weird sounding.

 

[FlyingOnFumes]

My SWAG would be that it has something to do with a positively cambered airfoil (prop) with a negative AOA (full beta at -5*)? More turbulent flow as a result?

I love that sound.

I concur. Plus, you are going against V_infinity (oncoming flow, a.k.a. relative wind).

 

[Beans]

Any insight into why beta sounds so different?

Btw I haven't gotten my + rep yet... just sayin'... :icon_smil

Aren't you in Adv Helo?

Aaaand wrt beta noise.... no idea. I'm sure someone published something about it way back in the day when it was more "cutting edge."

 

[porw0004]

Not me, in Primary FAMs.