You Got to Be Kidding Me!

Engineering Break: Thoughts on The ME 109 Versus the ‘Spit’

Posted in Aircraft and Flying, Engineering by Stacy McMahon on June 5, 2007

One of my very minor hobbies is reading “period” pilot reports about WW2 fighter planes. The other day I Googled up a dour and uncomplimentary review of the Messerschmitt 109, written by Kit Carson for Airpower Magazine in the mid-70s, and based on some apparently incomplete and selectively reported data from wartime reports page. Shortly after, I found an anonymous response. Diplomatically titled “Why Carson was an Idiot”, it’s an astute, sarcastic and occasionally quite humorous point-by-point rebuttal (italics are quotes from the Carson article):

Intention of this page here is to correct serious errors in this particular article, which happened due to a serious lack of knowledge about the 109 technics and design history. It begins right here (quotes from the article in “italics”):

“But another household work, the highly propagandized Me-109G, was obsolete when it was built and was aerodynamically the most inefficient fighter of its time. It was a hopeless collection of lumps, bumps, stiff controls, and placed its pilot in a cramped, squarish cockpit with poor visibility.”

The nameless author, who does not appear to be a native English speaker, follows up this opening shot with some fairly devastating comparisons of Carson’s quotes to data on competitive planes, especially the Spitfire.

” the engineers screwed up the center of gravity, and 60 pounds of permanent ballast had to be added to the rear of the fuselage to get the C.G. back.”

An incredible 1.1% or less weight was added. Boah, what a big deal when it helps to improve fyling characterists, eh? But it´s getting even better. Look at this weight statistic of a [Spitfire Mk IX]:

What can we see? Spit 9 carried 5×17.5lb = 87.5lb ballast weight. Isn´t it interesting that Carson considers the ballast/trim weight on a 109E as an incredible design fault, but obviously didn´t know (or avoids to mention) that the Spitfire series (at least the 9) was blessed with even more ballast weight? This alone says a lot about the bias of Carson and his poor knowledge of WW2 fighter technics.

To borrow a phrase, read the whole thing (FYI the linked page includes some wartime photos with visible Nazi insignia). Besides the snark, it’s full of interesting tidbits for those of us who are interested in how airplanes work. For example:

I already discussed the influence of lift coefficient. What the report assumes is simply the same lift coefficient for the 109 and Spit. Of course, if we calcualte just with wingloadings then we get for the radius of the Spit: 829feet / 32 * 25 = 695feet ~690feet

Unfortunatly – i can´t say it often enough – it´s lift/weight that determines the minimum radius and not just wingarea/weight. The people who wrote the report and Carson are doing calculations on such a simple mathematic and aerodynamic basis that i´m wondering how they got their degree in mechanical engineering or aerodynamics!

I don’t know where they got it, but reading that makes me feel almost as if I could get one of my own if I had the author’s phone number! And the point about Carson’s knowledge of WW2 fighter technology is an important one. It’s tempting to look at the crude (by our standards) tools of the past and conclude that their designers were ignorant or just plain stupid. Those who blithely say “I could do that!” usually learn the hard way that reality is far more complex. To take just one example, it’s an article of faith among modern kayakers that their boats are simply dangerous, impossible to keep in a straight line and prone to capsizing. Turns out, as National Geographic once reported, that Inuit hunters designed those characteristics out of their “primitive” bone-and-skin kayaks centuries ago. Their boats flex with the waves (much like my inflatable one) instead of being tossed by them.

Anyway, I’ll leave you with something a little bit airplane-geeky but very cool nonetheless — The Messerschmitt factory was an early user (the author claims it was the first) of wing fences, though they didn’t make it into production. Fences are something of a kludge, but are effective for preventing the development of sideways airflow on wings (the air has to flow front-to-back in order to produce lift.) They appeared on several early jet fighters including the MiG-15, and are still used on many today. Our anonymous author gives us a shot of their origin that at least I have never seen before:

Hispano 112 (ME 109 with Merlin engine)

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