C-130 "strange" variants .... need help !!

[Captain Canada]

The jet pods on the Herc look awesome, but even better is the Sofuffle maker in the cockpit !

Those crazy frenchmen !

 

[Tophe]

a photograph of the prototype (only left wing installation, not complete)

I misread, sorry...  A C-130B has been transformed into BLC prototype, but not one wing only: the text meant the Continetal compressors 356-17 were replacing the external T-56A engines, so this was another 2-engined Hercules, and with jet pipes...  

[Tophe]

You say "blow the boundary layer"

Yes, but - well, how to say? - I understand 'blow outward' but I am very surprised that you say as well 'blow inside', do you say 'suck' like for a baby with milk. Well, let me ask a question that may seem stupid for you: what is the action of a vacuum cleaner? Don't answer vacuum-cleaning! Maybe this is 'pump inward' while 'blow' means 'pump outward'...

[Tophe]

The jet pods on the Herc look awesome, but even better is the Sofuffle maker in the cockpit ! Those crazy frenchmen ! 

Uh, Captain this was a Lockheed US design, only the journalists were French... And the "souffle" part in the cockpit is a command panel of switches, not the pump machine. Well, this is no excuse, I am a crazy Frenchman anyway... If my forefather had moved to Canada, I would be a crazy Canadian, nationality is out of the question. I would be honoured to be Lieutnant Canada in the What-if army...  

[elmayerle]

a photograph of the prototype (only left wing installation, not complete)

I misread, sorry...  A C-130B has been transformed into BLC prototype, but not one wing only: the text meant the Continetal compressors 356-17 were replacing the external T-56A engines, so this was another 2-engined Hercules, and with jet pipes...

Look at the picture, there are two sets of propellors on that side.  The aircraft still has four engines in addtion to the compressors for the BLC system.

[elmayerle]

You say "blow the boundary layer"

Yes, but - well, how to say? - I understand 'blow outward' but I am very surprised that you say as well 'blow inside', do you say 'suck' like for a baby with milk. Well, let me ask a question that may seem stupid for you: what is the action of a vacuum cleaner? Don't answer vacuum-cleaning! Maybe this is 'pump inward' while 'blow' means 'pump outward'...

BLC works by essentially blowing air into the areas where the boundary layer would normally be separating from the wing.  This high-energy air keeps it attached and makes for better lift and lower drag.  It also allows the layer to stay attached over large flap angles, again giving the improved lift.

[Swamphen]

what is the action of a vacuum cleaner? Don't answer vacuum-cleaning!

Uh-uh. I ain't opening THAT can o' worms...    

[Tophe]

Uh-uh. I ain't opening THAT can o' worms... 

My English is not fluent enought to understand the joke, sorry...  do you mean the vacuum-cleaner plastic pipe is like an earthworm and it is surprising that worms can clean a house?

I have not received this time the usual English lesson of my dear What-if teachers, well I try to translate anyway (I mean "my way": imperfect English).

From Air Revue, Feb.1960:
<< 2 methods are usually used to icrease lift by boundary-layer control : pump inward or outward air on the plane surfaces. Each method has advantages and drawbacks, and both should have been adapted to the C-130. It seems interesting to explain WHY, after deep study, the blowing system has been chosen as the most appropriate.
To choose, the criterions were: first, providing the required performances ; second, minimum change to the C-130B basis, to decrease cost and ease the transfer on existing manufacturing lines.
- 1st system : pumping inward on all the wing surface. Advantage: requiring a far lower power (10 times less) than pumping outward. Drawbacks: the maximum lift factor would have been lower, and most of all that would have required a new wing.
- 2nd system: pumping inward only on the flaps' leading edge. Advantages: cheap modification of the wing, low required power and weight addition. Drawbacks: maximum lift factor even lower, huge sensitivity to any configuration change.
- 3rd system (Arado): pumping inward air on the lower part of the flaps to blow it on the ailerons and external part of the flaps. Advantages: low modifications and low required power. Drawbacks: very slight increase of lift, very complicated way to add security in case one engine of the BLC-system fails.  
- 4th system (selected): blowing pressured air on the landing flaps and control surfaces. Advantage: very bigger improvement of lift (because pumping-in only prevents "no more lift" on the concerned surfaces, while pumping-out actually increase lift by establishing a controlled airflow on these surfaces). Drawback: requiring much power and weight addition (in the blowing way, more power increase performance, this is different from pumping inward where more power increase nothing). >>

Well, maybe Evan will tell us the principle of the Boundary-Layer-Control, not much explained here. I thought (but for cruise performance/speed & oil-saving not take-off/landing like the C-130?) it was preventing the dragging vortexes of the air-flow leaving the wing contact. You may prevent the leaving by pumping inward, or prevent the contact by pumping outward (blowing). No, engineer? Give us the keys to understand, please...    

[elmayerle]

From Air Revue, Feb.1960:
<< 2 methods are usually used to icrease lift by boundary-layer control : pump inward or outward air on the plane surfaces. Each method has advantages and drawbacks, and both should have been adapted to the C-130. It seems interesting to explain WHY, after deep study, the blowing system has been chosen as the most appropriate.
To choose, the criterions were: first, providing the required performances ; second, minimum change to the C-130B basis, to decrease cost and ease the transfer on existing manufacturing lines.
- 1st system : pumping inward on all the wing surface. Advantage: requiring a far lower power (10 times less) than pumping outward. Drawbacks: the maximum lift factor would have been lower, and most of all that would have required a new wing.
- 2nd system: pumping inward only on the flaps' leading edge. Advantages: cheap modification of the wing, low required power and weight addition. Drawbacks: maximum lift factor even lower, huge sensitivity to any configuration change.
- 3rd system (Arado): pumping inward air on the lower part of the flaps to blow it on the ailerons and external part of the flaps. Advantages: low modifications and low required power. Drawbacks: very slight increase of lift, very complicated way to add security in case one engine of the BLC-system fails. 
- 4th system (selected): blowing pressured air on the landing flaps and control surfaces. Advantage: very bigger improvement of lift (because pumping-in only prevents "no more lift" on the concerned surfaces, while pumping-out actually increase lift by establishing a controlled airflow on these surfaces). Drawback: requiring much power and weight addition (in the blowing way, more power increase performance, this is different from pumping inward where more power increase nothing). >>

Well, maybe Evan will tell us the principle of the Boundary-Layer-Control, not much explained here. I thought (but for cruise performance/speed & oil-saving not take-off/landing like the C-130?) it was preventing the dragging vortexes of the air-flow leaving the wing contact. You may prevent the leaving by pumping inward, or prevent the contact by pumping outward (blowing). No, engineer? Give us the keys to understand, please... 

The key concern is keeping the boundary layer attached so that you can control lift and draq as you desire.  For cruise flight, you want to reduce the turbulent boundary layer, that forms as the flow moves aft over the wing, in order to reduce drag; you do this by sucking the air from the turbulent region into the wing and dumping it out elsewhere - the Northrop X-21 is an example of this concept.  For landing, very low-speed flight, and, to a lesser degree, takeoff, you want to keep the boundary layer attached with the flaps lowered in order to get higher lift; as I described earlier, you do this by blowing air at the correct location to keep the flow attached (if memory serves me correctly, at least part of this is using the Coanda effect).  I don't know if the other two systems that article mentioned have been tested in flight, but I know these two have been.

I hope I've made this a bit more clear.

[Tophe]

Thanks a lot!  

[Swamphen]

When you've caused big trouble, you've "opened a can of worms".

[Tophe]

Thanks for this lesson too... ^_^  

[Tophe]

And thanks to Scooterman and the MAP, the weirdest of all:
http://www.cardatabase.net/modifiedairline...php?id=00001831
 

[Scooterman]

And thanks to Scooterman and the MAP, the weirdest of all:
http://www.cardatabase.net/modifiedairline...php?id=00001831

That would be a Super-Duper Herk!

And you're welcome for the link!