ORIGINAL: 8178
ORIGINAL: TonyF
Retracts were really never about drag reduction. If some thought that was the case, it really wasn't. Now if you put doors on the gear and close up the holes, now you have drag reduction. But retracts were always about the look. They just make the plane look much better, particularly models of the era. Also a small improvement in bringing the weight of everything closer to the center of the model.
True it would be cleaner with gear doors, but take a strut and wheel and hang it out your car window at about 90 MPH. You’ll be amazed how much force it takes to hold that wheel in the slipstream.
And a good point 8178 (I'm not an an aero engineer but do have an aero degree) as the gear are part of the parsasitic drag problem.That problem is that as speed increases the parastic draginfluence does too; that is the parasite drag curve rises as speed increases. Your example is good one too, or you can simply hold your hand out the window to get a feel for it. Now if you hold your hand palmflat and parallel to the windstream you'll notice little force on it, as you increase that angle you'll feel the force pushing your flat palm back (but maintain the position with arm muscle), it gives you an idea of the lifting forces a wing generates.That's oversimplified but a good example for the unitiated. Now start hanging stuff off of that palm (wing) and you can begin to see how it interferes with the wings ability to use the lift generated, that's intereference drag (one type of of parasitic drag). So ultimately retracting the gear likely is beneficial, but just how much is open to measurement because the mechanics of retracting the gear do increase weight, leave open bays etc.
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