Some new items……..

Well, all has been moving forward of late, so much so however that I have been neglecting posting. So here we go. The Me 109 flew well, but only after installing a slightly larger powerplant. As with all designs that push the components to the limit of their abilities, some things can sneak past you. In this particular design it was wing thickness. There is a distinct relation between lift and drag, and for you budding airframe designers, this link can be mystifying at times. For instance, a more draggy WWI Taube design (see the Taube category to the right for an example) with flying wires and drag inducing details, flying on the same engine as the ME-109 design should be much draggier (and it is) than the clean 109 which is much more slippery and aerodynamically clean. So therefore, putting the exact same engine into the aerodynamically cleaner 109 of the same wingspan should result in its flying even better than the old draggy Taube…..right? Wrong….in fact, it wouldn’t climb out at all…..only do an extended glide into a belly landing every time. So why?  The answer…….wing thickness. I noticed after building the 109 that it had quite thick wing cross section. Now with plenty of power this can produce a huge amount of lift….but in hindsight, in designing for this smallish powerplant, I should have opted for a thinner wing. The thinner wing produces less lift, but the gained reduced drag was what this design needed for this powerplant, not more lift. Look at it this way….the ratio of drag that was contained in the thicker wing, although accompanied by the potential for more lift, would be the equivalent of (drastic example here…it is a bit more subtle really) to putting an all metal Cesna wing on a go-cart engine powered ultralight. Sure the wing will work….but this little guy hasn’t got what it takes to make it work…its small power won’t allow the wing to enter its correct range of operation. Long story short…..bad choice for this engine…..but not out of the ballpark completely. So I slapped a larger motor in…flew it….a friend saw it and fell in love and it got solded!!  So….enough on aerodynamics. Some new projects are in the works…..some ancient/primitive instrument creations…..and a new plane design that (is cartoonish!!) and I hope I can make simple enough to be buildable by others. The following image is a hint…..more to come.

airco-dh2

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