Sandy, it will only make more of a difference if you're putting the flaps down a lot. Take the 3" flaps and draw an imaginary line from the center of the leading edge to the bottom of the deployed flap at max. Now if you have the 4" flap and only deploy it to the same amount down you will have the same amount of lift/drag, although the flap will be at a slightly lesser down angle.
If you deploy the 4" flap down more you will get more drag, less lift, as you will with any flap.
How's that ?

Oh, and you know blanking is a characteristic of angle of attack, when you're talking about about flaps blanking an elevator that's set above it. The turbulent air could hit the elevator if you flare a lot, but you know you land a hurricane on its mains, so it shouldn't be a problem.

increasing flap chord increases the camber and the pitching moment.  You have flown and I have flown tail draggers
nothing i flew had drag flap.  70 deg. of flap was drag flap back then.  You came in with a lot of power on and landed in a short distance.

the 3 inch chord flap at say 30 degrees will give you a nose down pitching moment. which increases forward visibility.

i think that the blanking idea comes from the way the model handles when a lot of flap is applied.


since these aircraft did three pointers all the time, then i think that the use of max flap should NOT be a problem, unless based on reynolds number the scale size and area of the horizontal tail are smaller than they should be.

i am trying to visualize an approach in say a chipmunk with max flap.  all i can remember is the thing being tossed around by turbulence over trees and such, dropping a wing and picking up with rudder.  can't speak for the Harvard, haven't flown one.

http://www.vaillyaviation.com/images/Hurricane%20landing%20technique.pdf

tail setting angle?
take a look at the mk1 hurricane picture http://en.wikipedia.org/wiki/Hawker_Hurricane
the tails getting angle is decided, in part, by the downwash on the tail.  in the picture (which is hi rez) it appears to be quite significant i.e. quite a lot of degrees.  also the elevator angle on approach/flypast, which this aircraft is, is not that excessive, hence the advice to keep the speed up on landing.


i thought these (full size) things landed at 80 mph?  must be dreaming.

Fussing over details    Good stuff Sandy.  Looking forward to reading more as your build progresses.



Don't want to hijack your thread, but since the topic is flaps:  today I learned that the Bf 109 (Me 109) drooped its ailerons by about 11 degrees when the flaps were deployed.  And, it compensated by increasing the angle of incidence of the horizontal stab.  That's pretty cool for a design that first flew in 1935.  Unfortunately, the book I am reading didn't give me a reference source to confirm this feature.  I'm gonna dig for that one.

I agree.  The Haynes books are great.

I have the one for the Spitfire; thoroughly enjoy it.