What is referred to as “Coke bottle shaped” or area rule in aviation design. It’s a more efficient fuselage design for aircraft, because it results in less drag. I doubt it makes a measurable difference at E-type speeds.
I’ve always felt the car was so shaped. Easy enough to tell. Tape a string to the top of the front wheel opening and stretch the string to the top of the rear wheel opening. If there is a gap between the string and the door the car is coke bottle shaped.
The reason I ask the question is that my car had been so badly misshapen and repaired that I cannot be sure if it is now the correct shape.
I have run a string down both sides and as I move towards the top of the doors this coke bottle shape is more apparent.
Quite subtle but it is there.
I have run a line from the B post forward to eliminate the rear wings from the measurement, but there is still a coke bottle shape at the top. only about 1/4" though.
It looks ok, but that might all change when it is in glossy paint.
I just wondered what others had if they ran a straight line down the sides?
My car has a very straight un-rusted and unmolested body. I have a 60" straightedge, which stretches from the front tip of the rear bumper blade almost to the front edge of the cowl. Using this, it looks like the sides are dead straight to me I would have been surprised to find otherwise, since that would have required complex compound curves, for very little stylistic advantage.
Yes I have seen that, but if you look at the reflection down the side of this random selection of photos from XKE Data, you can see the the arched reflection that to me means that there is some shape, although it is straight at the sills?
I don’t know the answer to your question, but have one comment. You say that your car is a FHC but provide no other details. It would help us if you add details in the “my cars” section of your profile, or at least tell us in this thread. I would not assume that all years and all series are the same in this regard. For example, I believe that the rear areas of the FHCs were subject to extensive changes in profile sometime in 1962. Clive Wilkinson has made frequent reference to this in some of his postings, and this is borne out by references in Haddock, Clausager etc. The answer to your question might be YES in some cases, and NO in others.
Ron James posted an interesting picture about 6 weeks ago in this thread:
His post was 24 out of what is currently 135 if you want to find it. I am assuming he doesn’t object to me posting the actual image here for your review:
Good point David. I guess I just don’t have the eye for it. One of many reasons I’m not an artist. I don’t see the hour glass shape in this picture or in the “sketch” posted above by Doug. I see two very straight (not quite parallel) lines in the sketch.(?)
The line is nearly dead straight. There should be no dip amidships. No hourglass shape. Even the XK120, which is a deceptively curvaceous design, features mostly long straight lines throughout.
Take a straight edge (I just used an old envelope from the junk mail I’ve just been going through), and lay it on your screen along the side of the photo of the Lightweight. Move it so it just touches the side of the car at the front and rear wings, and you’ll see a small gap in the center. It probably only amounts to 1/2" or so full scale. On the Lightweight, it appears that most if not all of the “curve” is aft of the B-pillar, and is probably just due to flares on the rear wheels to accommodate the larger width tyres the Lightweights used.
[quote=“davidxk, post:7, topic:351606, full:true”]
For example, I believe that the rear areas of the FHCs were subject to extensive changes in profile sometime in 1962. Clive Wilkinson has made frequent reference to this in some of his postings, and this is borne out by references in Haddock, Clausager etc. The answer to your question might be YES in some cases, and NO in others. -David [/quote]
David, right, the early Coupes were different at the rear wings instead of being straight down the sides, although this won’t apply to the OP since his car is a later model. On the early cars, there was a definite bulge outwards of the rear wing after the door which can be seen in the photos here of my old '62.
A straightedge would touch all along the sides at mid height from the front of the front wing to the rear of the door, after which, the line would move out. And that straightedge would not be parallel to the car’s center-line but further out at the front.
That is only at mid height. I don’t have my notes here but IIRC, the tops of the sills are parallel to each other and therefore also to the car center-line.
Thanks for your comments guys.
Looks like I have a bit more preparing to do.
I checked today and it is probably only about 1/16" to a 1/4" off. I could probably fill it, but I don’t want to go in that direction.
Paul
Not bad, then. Figure out where the sight line needs to be. It will be very close to dead flat, then a way to stabilize the plane. Cut, weld and reweld as needed. This is my current project, fabbing and installing a wing panel on my XK120. Same principle.
