Thank you! Very rare footage of 8 blades propeller on turboprop. ATR start to install this on new ATR plane model cause of fuel economy. Model will be on market near 2030. Looks good on A400!
Thank you for the video. So there are several questions I have: 1. When it starts, why doesn't it start flat (no pitch) to minimise air resistance and accelerate faster, particularly during startup? It looks like the opposite, the propeller is feathered, is this because there is no hydraulic pressure? 2. It looks like later on accelerates and the blades are pitched but them then accelerate but "flat' again to minimise air resistance? Are they testing the propellers? Thanks.
@@jeylful They normally stay feathered when the engine is turned off, because of wind forces to avoid windmill of the propeller, and sometimes they use proper straps, with propeller guards to hold the propeller, on windy days, once again to avoid windmill. The same happens on startup, the propeller is connected to a free turbine. To avoid counter rotating because of windmilling and to reduce drag when rotating the engines are started with the propeller in feather position. It reduces the noise too. They stay in this mode when the engine is in “ground idle” reducing noise and drag keeping the engine working freely without burning too much fuel and without stressing it, while pilots and crew perform the check lists. When they accelerate, the engine is in “flight mode” (they use other terms like alpha/beta modes) the blades are flat because the engine is in the ideal maximum RPM but the pilots don’t need thrust, because they are still stopped, so the blades stay flat. When they want to apply power/thrust to move you will see the blades changing a little the pitch (didn’t record that part, but I can record it). In turbofan/jets when pilots increase the throttle they increase RPM of the engines. On this engines, turboprops, the RPM is “constant” (works like a governor in a lawnmower) so when pilots increase throttle they change the pitch of the blades. With no throttle, but in flight mode, the blades stay flat providing no thrust.
@@Nelsonfasc Thank you for your answer. I still don't understand something.. you say that starting the propeller in feathered position reduces noise and drag but it seems to me that this is the opposite because whilst feathering offers less resistance against incoming air, the blade gives a lot of area/resistance against the wind as it spins. So if I were starting an engine I would have thought that you don't want this, but you would do the opposite and pitch the blades very thinly or even 0 so that they can spin with minimum resistance? Thanks again.
@@jeylful I understand your logic. And it makes sense. In the first question you talked about oil pressure, and that’s right too. Of course pilots could change the pitch of the propellers using the oil auxiliary pumps (we do that on ground with engines off for testing etc…)but that’s not a procedure. The engine on Idle ground mode is not creating enough pressure to pitch the blades to other positions than feather position. In windy days changing pitch prior to start engines can make them windmill a lot…creating drag on startup and stressing parts, because oil is not lubricating the engine. But now you can ask, but after starting the engine they could use the auxiliary pumps to change pitch? Yes but there is another factor. Optimal temperature. That is when the blades are on feather they don’t push air into the intake…that makes the engine achieve optimal temperature faster. In every other position they will push air into the intake. Even on flat position they will push air because the blades have an angle that is different from the base of the blade to the tip of the blade. So you may think that in reverse the air was pulled from the intake, and of course that cannot happen because it would stall the engine/compressor. So in reverse the base of the blades do not provide air to the intake, the angle is neutral flat in front of the intake but in the rest of the blade the angle is so (in this case reversed) they are pulling air to the aircraft front. That’s why some turboprop aircraft engines heat a little on reverse. The base of the blades is design to provide air to the engine intake during all flight operation and angles.
It is an Airbus, it has contra rotating propellers. C130 has props that all spin in the same direction and the props are much bigger on the Airbus. Regards from South Africa
Thank you! Very rare footage of 8 blades propeller on turboprop. ATR start to install this on new ATR plane model cause of fuel economy. Model will be on market near 2030. Looks good on A400!
Wow, nice video my friend
Nice
Wait a second why I see the Bangladesh logo I think UK is in relationship with Bangladesh
I dunno why, why would I know. ZI am definitely not a fan of countries, I am a fan of aviation
It's called blade angle change, not propeller pitch change....
you can also call it prop defeathering
Thank you for the video. So there are several questions I have:
1. When it starts, why doesn't it start flat (no pitch) to minimise air resistance and accelerate faster, particularly during startup? It looks like the opposite, the propeller is feathered, is this because there is no hydraulic pressure?
2. It looks like later on accelerates and the blades are pitched but them then accelerate but "flat' again to minimise air resistance? Are they testing the propellers? Thanks.
@@jeylful They normally stay feathered when the engine is turned off, because of wind forces to avoid windmill of the propeller, and sometimes they use proper straps, with propeller guards to hold the propeller, on windy days, once again to avoid windmill.
The same happens on startup, the propeller is connected to a free turbine. To avoid counter rotating because of windmilling and to reduce drag when rotating the engines are started with the propeller in feather position. It reduces the noise too. They stay in this mode when the engine is in “ground idle” reducing noise and drag keeping the engine working freely without burning too much fuel and without stressing it, while pilots and crew perform the check lists.
When they accelerate, the engine is in “flight mode” (they use other terms like alpha/beta modes) the blades are flat because the engine is in the ideal maximum RPM but the pilots don’t need thrust, because they are still stopped, so the blades stay flat. When they want to apply power/thrust to move you will see the blades changing a little the pitch (didn’t record that part, but I can record it).
In turbofan/jets when pilots increase the throttle they increase RPM of the engines. On this engines, turboprops, the RPM is “constant” (works like a governor in a lawnmower) so when pilots increase throttle they change the pitch of the blades. With no throttle, but in flight mode, the blades stay flat providing no thrust.
@@Nelsonfasc Thank you for your answer.
I still don't understand something.. you say that starting the propeller in feathered position reduces noise and drag but it seems to me that this is the opposite because whilst feathering offers less resistance against incoming air, the blade gives a lot of area/resistance against the wind as it spins. So if I were starting an engine I would have thought that you don't want this, but you would do the opposite and pitch the blades very thinly or even 0 so that they can spin with minimum resistance? Thanks again.
@@jeylful I understand your logic. And it makes sense.
In the first question you talked about oil pressure, and that’s right too. Of course pilots could change the pitch of the propellers using the oil auxiliary pumps (we do that on ground with engines off for testing etc…)but that’s not a procedure.
The engine on Idle ground mode is not creating enough pressure to pitch the blades to other positions than feather position.
In windy days changing pitch prior to start engines can make them windmill a lot…creating drag on startup and stressing parts, because oil is not lubricating the engine.
But now you can ask, but after starting the engine they could use the auxiliary pumps to change pitch? Yes but there is another factor. Optimal temperature. That is when the blades are on feather they don’t push air into the intake…that makes the engine achieve optimal temperature faster.
In every other position they will push air into the intake. Even on flat position they will push air because the blades have an angle that is different from the base of the blade to the tip of the blade.
So you may think that in reverse the air was pulled from the intake, and of course that cannot happen because it would stall the engine/compressor.
So in reverse the base of the blades do not provide air to the intake, the angle is neutral flat in front of the intake but in the rest of the blade the angle is so (in this case reversed) they are pulling air to the aircraft front. That’s why some turboprop aircraft engines heat a little on reverse.
The base of the blades is design to provide air to the engine intake during all flight operation and angles.
@@Nelsonfasc Thanks mate, interesting answers and information! Cheers.
3:48
Parece um aviao sovietico da decada de 70..
No Airbus, but Lockheed C-130 Hercules
Nah, it's an A400, the 130 doesn't have triple sets of wheels on the mains, nor does it have counter rotating props.
You are right th-cam.com/video/PUyfFiF-JTU/w-d-xo.html
Or a swept-back T-tail or swept wings
@@trancie27 that is correct
It is an Airbus, it has contra rotating propellers. C130 has props that all spin in the same direction and the props are much bigger on the Airbus.
Regards from South Africa