Spitfire Wing Structure, some specific questions.

MkI;

Thanks for having a search. The washout is something that I’d want to include.

Cheers, Tom.

Spitfire Wing Structure, some specific questions.

Hello Tom:
I checked my copy of the Mk.V manual for washout and airfoil details and it unfortunately only details the maintenance aspects (disassembly/reassembly) of the wing panels and components. My replica wings however, definitely have the ~2.5 deg washout built into them as near as I can tell by eye.
Mk.1
———

Hello Boys;

Ross, that’s one fascinating program you mentioned. I did the demo version, and it’s neat to first understand the NACA number system, then see how changes affect the foil shape. See, I told you you’re a tower of knowledge.

Question, what if the max camberline height is at 35% and not 30 or 40%, (a nice round number) ?

2213 at the root means the max camber location is at 20%. What would the number be if it were at 25% ? Or does the NACA system force the designer to stay within rigid increments? That would seem odd and undesigner-like.

You can see how little I know about the above, but I’ll dive into the demo and learn all I can.

Thanks again. Never saw that program before.

Additionally, I’m well under way with my fuselage wood mockup. My kids were climbing through it last night. The goal is to safely wedge 2 people into a Spit fuse that’s a 75% replica. Shrink an already tight aircraft, and add a second body. Piece of cake, but a ton of fun to work on. Will share pictures shortly, success or failure.

Cheers, Tom.

Programs..

Also you could try a Airfoil design program like this one to help get a wing together.
http://www.designfoil.com/
🙂
Not sure how they go with the Spits Plan view though.Thats our stumbling block at the moment…

Mk 1 and DazDaMan;

Yup, Terry’s a pretty good source of info, so I wrote to him. We’ll get a chance to test your memory.

And the specs for the Isaac’s Spit seem very similar to what I thought is/was true of the real Spitfire.

I don’t know enough about the NACA series nomenclature to take a number and translate it into a wing airfoil. I had a more patient look through all of the wing rib drawings today, and a lot of the scans are distorted enough to make things tough to just scale up or scale down. I had the same challenge when going through all of the fuselage frames and unskewing them to be useful. Quite an exercise, but more critical with the wing I assume.

Thanks again, Tom.

If it helps in any way whatsoever, the specs for the Isaacs Spit (from Jane’s All The World’s Aircraft 1982-83 – the only book NOT packed away!) say:

Wing section NACA 2200 series. Thickness/chord ratio 13.2% at root, 6% at tip. Dihedral 6 degrees. Incidence 2 degrees at root, -30 at tip.

Spitfire Wing Structure, some specific questions.

Tom:
I will check the manual again as its been a while since I’ve referred to it. Re centre of lift, I recall a comment from Terry Wilshire that he and Bob Cutting designed the Tally-ho 80% Spit to have the CoL @ 31% of MAC. I would qualify this statement however with a comment that my middle-aged memory is not what it used to be and hence would highly recommend you consult directly with Terry Wilshire. He is a very good authority on replica Spit aerodynamics.
Mk.1
——–

Hi Mk1;

Thanks for all the detail. Every bit helps me gain an understanding of the wing or other structure.

The stall seems very low on your aircraft, and I’ll bet that helps a lot on landing and roll out.

How much detail about the wing is there in the MkV manual? Rib detail, or just a general photo or two?

Tom.

Thanks Gents;

And Ross, please don’t pull your hair out! You’re a tower of knowledge. I need you to have hair! (actually I have no idea of your current folicular status, as I’ve never met you).

So my desire is to follow the original Spit wing as closely as possible, but with some concessions where needed or wanted. I don’t need to design a hotrod that’s hard to land (high stall speed) and stalls too easily (characteristic of a thin wing). Some slight added gentleness is OK with me, although not a lot.

I do have thousands of Spit drawings, so I guess I could answer my own question about thickness ratios, just print out a rib and measure. Continue from root to tip with all of the ribs.

One large piece of info I need is to know where the centre of lift is, so I can calculate moments about the CG. I think Mustangs have the CL well back from the leading edge, as compared to the average flying machine, do they not? Or am I just thinking of the point at which the airflow becomes turbulent? Can’t recall.

Thanks again, Tom.

Spitfire Wing Structure, some specific questions.

Hi Tom:
I will eyeball the washout on mine for you tommorrow when I’m at the hangar. I have attached the only “near perpendicular” photo I have (annotated with approximated red “wash axes”) and like you have speculated, there appears to be @ 2-2.5 deg negative washout between the root and the tip. If will also consult with old Charlie who built mine to see if he can remember although I doubt he will recall that detail from 37 years ago. The wing section on mine (indeed with the transitioning camber/chord ratio) also appears (by eye) to closely resemble the airfoil detailed in the Mk.V manual. I am at a loss re NACA numbers though.

As for flying characteristics (in the lower speed realm my 70% replica operates in, 45–>200 mph), I can comment that my (seemingly near scale) airfoil has no nasty habits. Power off stall (stick hard back) was @ 45 mph and a little higher with power on (half throttle, @ 50-55 mph with a slight buffet preceeding a gentle right wing break (which seems counter-intuitive to prop rotation). I have only had the airplane up to 170 mph with aileron loads appearing almost constant. Charlie dove the Spit to 200 mph at the Abbotsford airshow and he said she didn’t appear to handle much different than at the 145 mph cruise. Thats about all I can share with you as I only put @ 5 hrs flying on her before she went on the stand for her mods and refinish (2 years+ in progress now).

Regards, Mk.1
—————-

Hmm…. I’m sure the Isaacs Spit has the same aerofoil as the full size, and the flight characteristics are still pleasant enough.

Will have to search more, though, and the books are packed away! :rolleyes:

Bwaaahhhhaahhaaaahahahaaaa!!

I think you will find who really killed JFK will be easier to figure out than the spitfire wing.Believe me we tried (on hold for the moment actually)…………:diablo:
NACA numbers are 2209.4 at the wing tip (either at the tip itself or at rib 19,haven,t found a solid answer) and the root is 2213 at Number1 rib..we think.Washout I think you are close in the figures..
Scaling down full sized wings doesn,t mean scaling down the flight characteristics IIRC.Have heard RC Spits are vicious if you build the wing exactly to the real one.
Being an irregular elliptical wing makes finding the chord a pain as the highest point of each rib section changes throughout the wing length. Mr Mitchell was a genius when he designed it..In that respects I have no hope…:o Aircraft design isn,t really my strong point.Give me a hammer and some ally and I,m Ok though..:cool: