D.O., As I understand it, the real issue is that the wood in the sheer webs has the grain running horizontal (spanwise), not vertical. Horizontally mounted balsa wood has little resistance to sheer forces. Hence the folding wings. The issue is not pilot error.
I have personally seen the inside of one of these BoT wings and can validate that the sheer web is indeed mounted incorrectly. All it takes is making a cut in your MonoKote somewhere near the spar, and take a look for yourself. A piece of tape or another scrap of MonoKote will cover the hole you made. I have been building RC planes since the late 70's and have never seen plans calling for a sheer web with the grain running horizontal. For more info & commentary... http://www.rcgroups.com/forums/showthread.php?s=&threadid=148900 http://www.rcgroups.com/forums/showthread.php?s=&threadid=137664 Jon Stone ----- Original Message ----- From: "d. o. darnell" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, September 23, 2003 11:22 AM Subject: [RCSE] BoT Replacements > "No, Virginia; B O T does NOT stand for "Broken on Tow"! > > Well, I'm glad to see that Dynaflite is replacing broken BoTs. However > several questions concerning this fiasco which still remain to be answered, > unless I've missed something (which is highly possible). > > LIKE... > > ---- Why did these failures really occur? > ---- Are they all similar or different? > ---- Is this a materials-selection problem, quality control, or user-misuse > problem? > ---- Are the replacement units the same as the originals? > > I've been flying my BoT for a few months now and it seems to be holding up > OK so far. I do, however launch it "gingerly" on power winches, just as > one should with a built-up, wooden glider. Having flown this type of model > in the past, now, as back then, I use only as much peddle as needed to get > the Bird up to a reasonable altitude and then let it go to work, which it > does as good as any gas-bag I ever flew. No zoomie launches. That came in > with foam wings: Remember? > -- > As you may recall, I originally speculated that perhaps these structural > failures were due to the fact that the builder (end user, not factory) when > constructing the tip-panel joiners that consist of two aluminum pieces and > two ply pieces, didn't sand the ply thin enough to allow them to easily > slid into the boxes, or when fitting, forced then in, unknowingly cracking > the joiner boxes which eventually led to failure. > > Now no one is going to admit doing it but I'd bet this is just what > happened in many cases. I would like to see some post-mortum pictures. So > far one has yet come up with any. I'm just irritated due to the lack of > information. The information I have seen is usually second or third hand > and mostly opinion rather than fact. > > Meanwhile, Dynaflite seems to be keeping mum on the subject and not, to my > knowledge, providing any info to the general public. They may be afraid of > possible litigation, or maybe they just need to get rid of more kits prior > to releasing any updates? If they release an upgraded kit they're > probably going to be stuck with a lot of the "flawed" originals? However, > some of the originals have to be OK... don't they? > > If Dynaflite is "stuck" with a large quantity of "weak" wings, they could > designate them as "light duty electric" and come up with a motorized > version of the BoT fuse using a speed 400 or similar low-performance > electric package and avoiding hi stress launches altogether. And such a > design would be a real winner! > > But I guess what I'd personally like to see is just more information about > what is going on. I'm going to keep on flying my BoT because it's really a > great flying model. If it breaks, I'll get another. But IMHO, Dynaflite > is shirking responsibility not providing more data by which we BoT owners > can decide to fly, or not to. > I'm sure several hundred (or thousand?) of us who own BoTs now and future > potential customers would appreciate it. And, It's the right thing to do. > > Dynaflite could easily provide info on how to beef up existing wings for > structural integrity. Most of us wouldn't care and would get on with is, > just as if it were a crash repair. No big deal. If Dynaflite really wants > to do the right thing, they should put up a web page which provides info > and possible mods to existing BoTs. > > Whether of not Dynaflite will take any remedial action remains to be > seen. In the mean time, I'll be glad to be the focus point for information > gathering. If you have a injured BoT, or have peeled the skin back on > yours to check it out... whatever... drop me an Email (with pics if > possible) with pertinent comments. I'll collate the data and publish the > findings. How bout some "hard data"? Anyone? (Just the facts, Ma'am!) > > Hold your breath and tap gently, Quigley! > > > D.O. > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
