Why the Ju.87's semi-floating flaps/ailerons?

I don’t think that last explanation makes sense – the overall lift change will be the same in both cases, together with the movement of the centre of pressure.

What must be remembered is that aircraft companies were pragmatic and much less analytical than what we have now. The designers of the Ju87 will have used the seperate controls surfaces because they knew it worked: they had a backlog of experience and a considerable database to work with. Yet they abandoned the system for subsequent designs – I suspect this is because of the higher drag of the approach. The Ju87 was not a very fast aircraft.

The lightness and balance of the controls was not specifically due to the approach as opposed to any other, but to Junkers’ experience with it. Other companies managed similar qualities with more conventional controls. And others didn’t, of course, but that was part of the learning process of the time.

I don’t think that last explanation makes sense – the overall lift change will be the same in both cases, together with the movement of the centre of pressure.

What must be remembered is that aircraft companies were pragmatic and much less analytical than what we have now. The designers of the Ju87 will have used the seperate controls surfaces because they knew it worked: they had a backlog of experience and a considerable database to work with. Yet they abandoned the system for subsequent designs – I suspect this is because of the higher drag of the approach. The Ju87 was not a very fast aircraft.

The lightness and balance of the controls was not specifically due to the approach as opposed to any other, but to Junkers’ experience with it. Other companies managed similar qualities with more conventional controls. And others didn’t, of course, but that was part of the learning process of the time.

During the design process they would have been an option. Build a similar aircraft with traditional ailerons as well as a stuka, and let me know your findings. I DID say it was a guess.

In answer to your question, the consensus is that the slotted ailerons gave better handling at low speed, despite increased drag. The design was later revised by other manufacturers to become flaperons.

Reading more and more, it seems like its quite a clever design which differs from standard ailerons in quite a significant way: Standard ailerons are used to change the camber of the wing, generating higher lift and moving the centre of pressure rearwards. Slotted ailerons tend not to change the wing lift, but rather by changing the angle of attack of the control surface, all of the additional lift is generated on the control surface itself – there would be no need for boundary layer control in theory – IF the attached aircraft would ever build up enough speed or high alpha to warrant it in the first place!

Uber-EDIT: The above is NOT MY theory – but rather that of multiple unfounded sources!!!!!!!! SOMEONE PLEASE FIND DEFINITIVE PROOF OF CORRECT OR INCORRECT THEORY

end of section 2: low speed roll control & boundary layer invigoration http://www.exp-aircraft.com/library/heintz/airfoils.html

lift generating control surface: Page 4, figure 2b, left hand side column. (WARNING: REQUIRES MS WORD DOWNLOAD FILE!!!) – if the link doesn’t work, google search for Junkers flap TWITT……. http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CCYQFjAB&url=http%3A%2F%2Fusers.acsol.net%2F~nmasters%2Ftemp%2FSept03Ltr.doc&ei=EcRkUOuoOqq40QXv6oHgBg&usg=AFQjCNEuhXjA7I-XejMTzCyqFY-WDcbbfg

Pages 7 to 14 of the following show pressure distribution charts for a plain wing and one with the separate flaps (aileron will be identical) http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091690_1993091690.pdf

During the design process they would have been an option. Build a similar aircraft with traditional ailerons as well as a stuka, and let me know your findings. I DID say it was a guess.

In answer to your question, the consensus is that the slotted ailerons gave better handling at low speed, despite increased drag. The design was later revised by other manufacturers to become flaperons.

Reading more and more, it seems like its quite a clever design which differs from standard ailerons in quite a significant way: Standard ailerons are used to change the camber of the wing, generating higher lift and moving the centre of pressure rearwards. Slotted ailerons tend not to change the wing lift, but rather by changing the angle of attack of the control surface, all of the additional lift is generated on the control surface itself – there would be no need for boundary layer control in theory – IF the attached aircraft would ever build up enough speed or high alpha to warrant it in the first place!

Uber-EDIT: The above is NOT MY theory – but rather that of multiple unfounded sources!!!!!!!! SOMEONE PLEASE FIND DEFINITIVE PROOF OF CORRECT OR INCORRECT THEORY

end of section 2: low speed roll control & boundary layer invigoration http://www.exp-aircraft.com/library/heintz/airfoils.html

lift generating control surface: Page 4, figure 2b, left hand side column. (WARNING: REQUIRES MS WORD DOWNLOAD FILE!!!) – if the link doesn’t work, google search for Junkers flap TWITT……. http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CCYQFjAB&url=http%3A%2F%2Fusers.acsol.net%2F~nmasters%2Ftemp%2FSept03Ltr.doc&ei=EcRkUOuoOqq40QXv6oHgBg&usg=AFQjCNEuhXjA7I-XejMTzCyqFY-WDcbbfg

Pages 7 to 14 of the following show pressure distribution charts for a plain wing and one with the separate flaps (aileron will be identical) http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091690_1993091690.pdf

Well, it’s not as though slotted ailerons were an option…

I’m only pointing out that your assumption that the Ju.87 was “a heavy beastie to fly” doesn’t hold up in the real world.

Well, it’s not as though slotted ailerons were an option…

I’m only pointing out that your assumption that the Ju.87 was “a heavy beastie to fly” doesn’t hold up in the real world.

BUT that is with the slotted ailerons!

BUT that is with the slotted ailerons!

I’d hazard a guess that the JU87 was a heavy beastie to fly

Mustn’t make such assumptions. One RAF pilot, G. R. S. Mckay, who flew a captured Stuka a number of times, is quoted in Peter Smith’s new book “Junkers Ju.87 Stuka,” as saying the controls were so light that the “marked tendency was to overcontrol.” He characterized the flying characteristic as “excellent.”

And Winkle Brown also had high praise for the Stuka’s handling.

I’d hazard a guess that the JU87 was a heavy beastie to fly

Mustn’t make such assumptions. One RAF pilot, G. R. S. Mckay, who flew a captured Stuka a number of times, is quoted in Peter Smith’s new book “Junkers Ju.87 Stuka,” as saying the controls were so light that the “marked tendency was to overcontrol.” He characterized the flying characteristic as “excellent.”

And Winkle Brown also had high praise for the Stuka’s handling.

‘for light and effective control’… I’d hazard a guess that the JU87 was a heavy beastie to fly and this could be a way of assisting with roll control, particularly during high speed dives.

You do see them now, but morphed into a flaperon – full length flap and aileron combined, and usually on STOL ultralights and kitplanes….

As I said, just a guess.

Edit: A little research has shown that the Junkers Flap / Aileron system was quite a new innovation when the aircraft was designed and the slotted-aileron will give the wing an enormous amount of lift for little extra drag. The slot will re-invigorate the boundary layer air not only over the control surface, but over the whole wing, thus being able to delay separation of the airflow at high angles of attack. So combine that with the fact that the Stuka was heavy and operated at high angles of attack (particularly pulling out of a dive), and you get a fully responsive roll system which matches the aircraft’s predicted flight characteristics. Finally, the aileron will still be effective at very low speeds because it remains in free-stream air – in other words outside of any stalled, turbulent air over the wing. This ties in with the high angle of attack mentioned previously. Neat.

… or I could be talking Horlicks….

‘for light and effective control’… I’d hazard a guess that the JU87 was a heavy beastie to fly and this could be a way of assisting with roll control, particularly during high speed dives.

You do see them now, but morphed into a flaperon – full length flap and aileron combined, and usually on STOL ultralights and kitplanes….

As I said, just a guess.

Edit: A little research has shown that the Junkers Flap / Aileron system was quite a new innovation when the aircraft was designed and the slotted-aileron will give the wing an enormous amount of lift for little extra drag. The slot will re-invigorate the boundary layer air not only over the control surface, but over the whole wing, thus being able to delay separation of the airflow at high angles of attack. So combine that with the fact that the Stuka was heavy and operated at high angles of attack (particularly pulling out of a dive), and you get a fully responsive roll system which matches the aircraft’s predicted flight characteristics. Finally, the aileron will still be effective at very low speeds because it remains in free-stream air – in other words outside of any stalled, turbulent air over the wing. This ties in with the high angle of attack mentioned previously. Neat.

… or I could be talking Horlicks….

I always thought it was just the Junkers way of doing it, having carried it through from its early metal designs. It was a simple arrangement to build and maintain but was getting near its useful life with the JU87.

Someone will come along with a better reason I am sure.

Richard

I always thought it was just the Junkers way of doing it, having carried it through from its early metal designs. It was a simple arrangement to build and maintain but was getting near its useful life with the JU87.

Someone will come along with a better reason I am sure.

Richard