Metal Wing? Wooden Wing?
Hmmm
Apples & Oranges - Similar but Different.
Hmmm
Apples & Oranges - Similar but Different.
What I know about the Tailwind wooden wing you could just about fit into a thimble - well, maybe I know a bit more than that. I know more about a wooden wing than most know about a metal wing so I will try to enlighten us. At any rate, it will get a good discussion going.
On the information sheet and the plans that Steve sent to me when I contacted him and said I was interested in building a W10, it said the Tailwind wing span is 24 feet and its area is 90 square feet. .
My aluminum wing span is also 24 feet with a chord of 48", this translates to 96 square feet.
The wooden wing - a 24 foot span, 48 chord also, less 3 square feet on each wing tip area for the triangular shape - comes out at 90 square feet, just as advertised.
This difference in wing area is significant in a few ways which I will mention shortly.
The airfoil of the two wings is identical so if the span is the same and the airfoil is the same, they are close to being apples & apples or oranges & oranges, but I guess that is wishful thinking.
No two snowflakes are the same nor are two scratch built wings the same and to take this further I would venture to say no two sets of wings that Jim Clement has built have come out the same, damn close, but not quite the same, maybe.
Don’t fret, the wings we build will be close enough to do the job - like fly and fly well!
Probably none of us will be capable of building a Tailwind as well as Jim C. His will always go faster than the rest and they are the prettiest, probably the best fabricated. That noted, if any one of us built nine Tailwinds we would tend to get better at it and find many ways to make them more sophisticated and slipperier.
Back to the wings, it is not necessarily the wings, it is a myriad of everything that makes one plane go faster than another. If this is your criteria, going faster than others, by all means go for it and for a challenge try to beat Jim at his game but I doubt any can win.
In comparing the metal wing with the wooden wing, we see that the metal wing has about
6 square feet more wing area - same airfoil and same chord.
What will that give us?
Well, it gives us more lift, also lower wing loading and a bit more drag.
There is 2 inches more chord on the flaps and ailerons. With the squared off wing tips the flaps are longer and the ailerons are further out on the wings.
This gives the metal wing 2 square feet of aileron area and a flap area of 4.3 square feet as compared to the wood wing, aileron area 1.5 and flap area 2.7 square feet.
The lift from the extra 6 square feet of wing will allow it to take-off quicker. So will the lower wing loading which allows the wings to lift the weight of the plane sooner. This also says that the angle at which the plane can climb can be increased.
Since both sets of wings are the same length the extra drag comes from the parasite drag (skin friction) of the extra 6 square feet of wing.
I found the metal wing is a breeze to build, exceptionally simple for a first time builder.
All the parts are easily fabricated from the spars to the ribs. The ribs take about 15 minutes each being formed on a form block and since there are only 10 ribs to a wing it is done in no time. There are two spars in the metal wing, not three like the wood wing; this set up allows for the ailerons and flaps to be larger and more effective.
Metal wings have a natural resistance to weather when a plane cannot be hangared. Most manufacturers of commercial planes use metal wings and maybe in the future they will turn to a form of plastic but certainly not to wood.
Another feature of the metal wing is that the fuel can be carried in the wings. My wings are wet wings with 18 gallons in each wing, carried in the four bays (between the ribs) closest to the fuselage. This saves manufacturing a separate fuel tank and also puts all the fuel over the CG along with the pilot and passenger. No more retrimming as the fuel burns off. Another advantage of having the fuel in the wings, the fuel is not in the cabin with you. By moving the firewall forward and without the fuel tank in the cockpit the inside takes on larger dimensions. This allows the seats a wide range of adjustment.
I plumbed the fuel lines like a Cessna 172 except for a check valve I added to the line coming from the right wing. I thought it was fool proof. The fuel flow test at the engine was 30 gal per hour but the check valve didn’t seem to know that one day when the engine quit even though there were still 12 gallons of fuel on board.
One thing I learned that day is my Tailwind will glide forever if you pick the right airspeed and with a lot of flap and a little slip you can pinpoint your landing spot accurately and at a slow enough speed things don’t get out of hand.
But alas, that is a sermon for another day. Q
Addendum - My pal Callbie Wood, designed the metal wing for his Tailwind. He also designed and built the Forerunner with a metal wing. In his designs, Callbie leans to the side of strength and safety. I have run the metal wing past eight engineers in the aircraft industry and not one has picked out a flaw or potential problem.
The consensus - an extremely strong wing and very efficient.
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Home - SoCal Wind - Fuselage - Wing - Seat - The Building of my Tailwind
The Building of my Tailwind Continued - The Initial Flying - Journey Home
Metal Wing? - Wood Wing?