Pylon mounted wings superior?

On Saturday, February 8, 2014 6:09:11 AM UTC-6, J. Nieuwenhuize wrote:
It's mostly about improving the extent of laminar flow on both the wing and the fuselage. There's a huge area of turbulent flow there, which (at least in
theory) could be turned laminar. Bosman spoke about sucking off the LE of the
wing/fuselage section, but just taking wing and fuselage apart could yield 1-2 sqm of flow that's laminar instead of turbulent.
Thanks for sharing. Some interesting points.

But, to get those "1-2 sqm" of turbulent flow converted to laminar, you added almost that much area exposed to the flow. Some of which is still turbulent. Roughly 5 square feet of wing that was "hidden" in the fuselage is now exposed to air flow (2 feet spanwise, 30 inch chord). And, you have added a pylon that is something on the order of 24 to 30 inches tall, and probably more than 30 inches in chord. So, at best, another 5 square feet of wetted area of pylon. Probably more, because aerodynamically, you don't want max pylon width at the same chordwise location as max thickness on the wing.

Even if you can do it with a shorter pylon, it is still going to be difficult to get lower total drag with greater wetted area.

Steve

K

Op zondag 9 februari 2014 06:48:59 UTC+1 schreef Steve Leonard:

But, to get those "1-2 sqm" of turbulent flow converted to laminar, you added almost that much area exposed to the flow. Some of which is still turbulent. Roughly 5 square feet of wing that was "hidden" in the fuselage is now exposed to air flow (2 feet spanwise, 30 inch chord). And, you have added a pylon that is something on the order of 24 to 30 inches tall, and probably more than 30 inches in chord. So, at best, another 5 square feet of wetted area of pylon. Probably more, because aerodynamically, you don't want max pylon width at the same chordwise location as max thickness on the wing.

Even if you can do it with a shorter pylon, it is still going to be difficult to get lower total drag with greater wetted area.

Steve

K



It sure would be difficult, but the odds seem favorable. While you increase wetted area, the drag coefficient of that area (and the original area) goes down by a factor of something like 5 if you can get it laminar.
There are some other details at work; you gain lift, since now the wing is actually lifting (no dip in the spanwise lift distribution anymore), so you can actually shrink the wing area with a significant part of the wetted area increase. The pylon could be rather small, for a modern super-elliptic area distribution (winglets), we now need a root chord of something like 24".. Given the fairly low forces on the pylon (save yaw, groundloop), the pylon could be a lot smaller in chord and thickness.


I don't buy the point about anhedral. Many (ballasted) bigger ships have half of their weight in the wing, so we're talking about a 10" raise of the C of G or so. For many open-class ships, that's the difference between 1 and 1.5 G's (steep thermalling).

Bruce Carmichael seems to be the only one that has seriously pursued the idea of laminar-flow pylon wings. Time to win the lottery and start running a wind tunnel.

Thanks for the link to the BJ5 Clinton. Have been chasing pictures of that design for years.