Well, frankly I don't give a hoot who you support with your hard earned dollars.
BUT, I do care about the subject of overweight and out of CG flight ops. And, yes, I speak from experience....as an ex government pilot, I've legally operated several aircraft in excess of their legal maximum operating weights, so I know of what I speak. That's not meant to be insulting to anyone, the point is, I know what a heavy airplane flies like.
First, there are TWO very different and distinct issues here: All Up Weight (I always liked deHavilland's terminology as opposed to the term gross weight) is but one issue. The other issue is Center of Gravity. And, I find that a lot of pilots have some serious misconceptions about operating weights and many of them don't even think about CG.
All Up Weight first:
1) Frankly, you are pretty unlikely to cause an in flight structural failure by operating an airplane in excess of it's certificated maximum weight. These things (the airplanes) are seriously overdesigned, and are tested to sustain some incredible stresses. So, the one thing that many pilots seem to fear in their heart of hearts regarding operating at high weights--structural failure, is probably the least likely outcome.
2) What IS a guaranteed consequence of operating at weights in excess of the manufacturer's recommended maximum weight is that the PERFORMANCE of that airplane WILL be seriously compromised. This will be manifested in a LOT of different characteristics. The airplane will take significantly longer to get airborne, and it's climb rate may be severely compromised. Both of these factors may be seriously problematic, particularly in an off airport operation, where runway lengths and obstacles may present very real dangers to an airplane whose performance is compromised. And, here's the problem: Many new airplanes have excellent performance data, and the thinking pilot will develop similar data for an airplane like the cub, which doesn't have a lot of good performance data in its Pilot Handbook. The problem is, those performance charts only go up to the maximum operating weight. After that, you're a test pilot....a seriously underpaid one, at that.
3) BUT, there are other potentially serious effects of high weights on an airplane's performance as well. Consider that as you load the airplane to heavier weights, the airplane will fly at a higher angle of incidence, which changes the flow of cooling air through that pressure cowling and engine up front. Yes, I've seen CHTs go right on up to max in airplanes on floats on a warm day. So, you have to lower the nose....which further reduces your climb rate. After six full circles, maybe you can clear that ridge....unless of course, you get hit by a downdraft. Can you outclimb that downdraft at this weight? Any data to support that notion?
Now please don't go out and tell the whole world that I said you can't break an airplane by overloading it....I have no doubt that focus, determination, and talent can accomplish structural failure. And, remember, while you're operating at essentially one G in level cruise flight, one of those nasty little bits of turbulence can dramatically increase that G loading, at least momentarily. I once watched a Super Cub with two aboard (a high time 135 pilot and his mechanic going out to repair an airplane that pilot put up on the bank of a short lake on takeoff....) make three passes at the Fairbanks International float pond without getting airborne. They made it on the fourth try, and fortunately for them, they were taking off to the south on that attempt, so they didn't have to turn or climb right away, which they would have had they been taking off to the north. I'm sure that mechanic had a LOT of tools in the back of that Cub, and these guys were planning on camping, and I did note that the back seater was holding two boxes which APPEARED to be cases of beer on his lap..... The airplane didn't break, but I'm betting it took them fifteen minutes to get enough altitude to head north.
Okay, now let's talk about Center of Gravity.....
C of G is the Rodney Dangerfield of this topic, in my experience. Most pilots can give you a pretty good idea of what their airplane weighs prior to takeoff, even if it's a "wee bit" high. But, I've talked to quite a few pilots who couldn't give me even a ball park notion of where the CG was on a particular flight, except that "It should be okay".
And, flying an airplane that is outside it's approved Center of Gravity range, particularly one which is loaded aft, is a GREAT way to meet your Maker a wee bit earlier than you planned. For those who would argue that pilots are generally aware of their airplane's CG, just poke around on this web site and ask about the spin characteristics of the Super Cub....you'll see all sorts of folks piping up about getting dual instruction in a Super Cub in spins, or worse yet, having given dual instruction in a Super Cub in Spins. Consider that the Super Cub has both a restricted gross weight and a limited C of G for spins. And, folks, there aren't many Super Cubs out there that can legally fly with two "normal size" humanoids and ANY gas and be under 1500 pounds. Or, forward of that modified C of G.
So, what's the big deal with C of G? First, the vast majority of what you can load in one of these airplanes (most airplanes, actually) is going to move the C of G aft. So, as you load more and more stuff, the airplane not only gets heavier, but it's C of G moves aft.
What are the risks of operating an airplane outside it's C of G envelope? Well, if you're loaded forward of the forward limit, not much. The stall speed will be higher, but typically, to get to a forward C of G, you have to be loaded pretty light anyway, so the stall speed will be lower due to the light load factor on the wings...... And, the good news is that if you DO stall the airplane while it's loaded forward of its C of G forward limit, it'll generally recover from that stall quite readily. In fact, it's actually hard to keep a Cessna 172 with two aboard in a spin, because the airplane tends to recover from the stall unless you hold FULL and COMPLETE control inputs into the spin.
Also, consider that many of the modifications we install on these airplanes (Super Cubs) specifically prohibit spins. Note that the CC-18, while it permits ops up to 2300 pounds, spins are prohibited.
BUT, operating aft of the aft limit is a fish of a totally different scent. While stall speed actually decreases as the C of G moves aft for a given airplane, once you exceed the aft C of G limit, you are a test pilot, and in fact the airplane may not be capable of recovering from a stall. That's not a good thing to discover as you're trying to clear those trees, which are viewable in the TOP of your windshield, because your climb performance is severely limited by the load factor you've subjected the airplane to with all that "Stuff" in the back. Further, aft C of G stalls often tend to give little if any aerodynamic pre stall buffet. So, you may not be able to see it coming.
I believe that many of the "over weight" accidents that we see out there are in fact likely caused by this combination of factors....heavy weight hindering performance and an Aft Center of Gravity precluding recovery.
Consider the gent who tried to take off from Merrill Field a while back with his family and a LOT of stuff in a 206. The airplane didn't fail structurally, but it simply couldn't fly at the angle of attack that he placed it in.
Finally, I can tell you that it is quite easy to get complacent about operating at high weights, and ignoring Center of Gravity, at least to some great degree. I have been guilty of both in past, but no more, thank you. I don't get paid to fly at all nowadays, let alone collect a test pilot's salary. Oh, yeah....test pilots have spin parachutes and wear a parachute on their backs as well when playing with these demons.
So, do I calculate a weight and balance every time I fly? Sorta. I may not do the math every time, but I know precisely how much PAYLOAD (a term not found in the FAA's lexicon, but in my definition, Payload is defined as "Useful Load" minus the weight of the pilot, but then again, some of my bosses haven't considered pilots to be very useful....) my airplane can carry, and I have calculated sample loadings for the airplane. I know very closely how much weight I can carry and where it needs to be placed in the airplane. For these simple little airplanes, that's not too challenging. A Boeing presents an entirely different scenario of course. But, an airplane that's new to me, or a "unique" loading will cause me to drag out the paper and calculator and actually compute a weight and balance.
Hopefully, this little treatise will have put everyone to sleep, and they'll have forgotten about the member/non member nonsense by now....
MTV
