Slats vs no slats: Flight test

[BC12D-4-85]

So here we are....bird wings with alulae (from an earlier post) benefit from a delay of reversion flow of air on the upper wing's surface (like from aircraft slots or slats), plus an energization of the boundary layer (like from VG's or similar LE devices).

JimC mentions "local control of camber distribution". This article discusses wing lift in general, and at the end presents the term "shape morphing" in birds as another method of controlling lift and its span wise distribution.

Or we can add lightness to our aircraft and enjoy the simplicity of low wing loading/drag, and higher relative power loading.

Gary

 

[JimC]

"Or we can add lightness to our aircraft and enjoy the simplicity of low wing loading/drag".

Two caveats to that. We won't get the wingloading down to the realm of typical animal flight, and our drag coefficients even when reduced, will be much greater than theirs.

 

[BC12D-4-85]

I'll leave it with this.....for me I'd rather regress to a very light Cub (or my Taylorcraft) than add weight/wing complexity/big engine with the hope that the mods will support the higher EW plus any added large load. I wonder how many have ever experienced a truly light aircraft?

Gary

 

[skywagon8a]

I wonder how many have ever experienced a truly light aircraft?

Gary

I flew an Aeronca C-3 with an A-65 once long ago, don't remember much about it.

 

[BC12D-4-85]

I referenced this earlier in the thread (https://commons.erau.edu/cgi/viewcontent.cgi?article=1300&context=edt). The author analyzes the Clark-Y airfoil (similar to Cub's) with LE slots or slats. Skip to page 95 for his conclusions. Basically it takes AOA to fully use their benefit; often more AOA than typically available. Partial span is also analyzed. Flaps and other passive LE devices work without all that mechanical fuss.

Gary

 

[JimC]

"I'll leave it with this.....for me I'd rather regress to a very light Cub (or my Taylorcraft) than add weight/wing complexity/big engine with the hope that the mods will support the higher EW plus any added large load"

If I add 1% to the weight and increase the max lift coefficient by 10%, I'm a happy camper.

'I wonder how many have ever experienced a truly light aircraft?"

Most of us, I would think.

An O-200 putting out about 115-119 hp at 2850 rpm is about all I need in a J3. When I want more, I'll drop the nose a bit and let the rpm wrap up (though I don't like to run the O-200 more than 3100 for more than a few seconds).

 

[BC12D-4-85]

If I add 1% to the weight and increase the max lift coefficient by 10%, I'm a happy camper.

'I wonder how many have ever experienced a truly light aircraft?"

Most of us, I would think.

An O-200 putting out about 115-119 hp at 2850 rpm is about all I need in a J3. When I want more, I'll drop the nose a bit and let the rpm wrap up (though I don't like to run the O-200 more than 3100 for more than a few second).

Any added Cl or drag I'd rather get from flaps than slats or slots. Flaps added to a J-3 or PA-11 are +20#. At least I'd still see the runway or water body when landing. And on floats or skis the flaps would be available for takeoff when AOA (required for really activating the LE) is limited by gear configuration.

Most today start with heavy Kansas metal aircraft and progress into even more of the same. Not here of course, as we started in an earlier era of aviation in Alaska.

Yes the power is good especially if the prop will enable it at low airspeed. My C-85 Stroker is a minimum at 1320# conventional or 1351# floats.

Gary

 

[JimC]

85 Stroker is a good engine.
I'm not used to being able to see the runway on short final. Sounds nice.

 

[BC12D-4-85]

Observing the LZ from a J-3...don't you just stick your head out the door? Big thing off airport are obstacles that are best avoided.

Except for the Helio Courier I don't see many commercial ops using the new tech STOL devices. Bush pilots might but not sure about the insurability of the LE mods.

Gary

 

[JimC]

"Observing the LZ from a J-3...don't you just stick your head out the door? "

Depends. When landing on the sandbars and islands in the Mississippi and White Rivers, yes - looking for buried snags.
Otherwise no, I just look out the door and side window.

 

[JimC]

Why is hull insurability relevant?

 

[BC12D-4-85]

Why is hull insurability relevant?

For commercial 14 CFR Part 135 air carrier and operator certification. If they chose to use the plane in their business and not recreation. Not sure about Part 91 and was just wondering if non-STC'd was insurable for hull, liability, or both. Someone here knows.

Gary

 

[JimC]

Liability coverage interests me. Hull, not so much.