Flying Bozo Posted December 9, 2011 Report Share Posted December 9, 2011 The dimensions given in the aircraft operating instructions P 5-1 for the distance from the leading edge of the wing to the nose gear called "a" is 35.63 inches and the number given there for the distance between the nose gear and the main gear is 58.07 inches. On my weight and balance sheet for my CTSW on the lower right hand corner of the sheet those same distances are different by quite a bit "a" being 33.66 inches and "b" being 56.69 inches. This might sound insignificant but when determining the weight and balance they are used to calculate the empty weight center of gravity or the empty weight moment. So one place a=35.63 and the other place it is 33.66 then b=58.07 and the other place it is 56.69 ???? Can anybody shed some light on this. It has to be a misprint at one place or the other because the wheels don't change position. What gives??? Help Larry, flying Bozo Link to comment Share on other sites More sharing options...
Runtoeat Posted December 11, 2011 Report Share Posted December 11, 2011 Larry, I think that your statement "the wheels don't change position" may warrant some discussion. Here's my 2 cents and anybody is welcome to comment. I was at one time a design engineer for car body structures and base my comments on this background. Probably both the front gear and the main gear do vary in their location compared to the wing datum point. I will venture a guess that all CT aircraft probably will vary somewhat and will be unique to one another due to variances in structure surfaces. Some parts of the structure are probably not held to as close a tolerance as others during the molding process. For instance, the wing root areas with finished surfaces which locate the wings may have dimensions that are closely held. The same for the control surfaces and door/fuselage/windscreen surfaces. Regarding the surfaces which locate the landing gear, I would think that the front wheel probably will vary the least compared to the main gear among CTSW's. The front gear leg is located by the engine structure which, in turn, is fastened to a flat cowl surface that may be held fairly close "dimensionally" to the fuselage which is held close to the wing attaching points. The dimension for your front wheel from the datum point is the same as mine; 33.66". I suspect that the main landing gear is probably going to show more variance among different airplanes. The dimension for "G2" relies on one taking a point out in space at the end of the long landing gear leg. The location of this point relies on the nesting of the gear leg into a laid up "pocket" in the bulkhead structure which probably has a variable surface. Additionally, the aluminum strut itself is a round and tapered member. The variance resulting from this attachment situation is magnified out at the end of the gear leg where point "G2" is located. Measurement of "b" varies as a result. Measurement "b" is further affected by the variance of the fore-aft location of the front gear leg. Your "b" dimension is 56.69" and my "b" dimension is 56.30". Based on the possiblilites for variance that can occur, I would expect to have other CTSW owners indicate that they have dimensions that will vary from our dimensions, if actual measurement is made of the airplanes. The important point to make is that one doesn't want to have the CG calcuation made from the "design" dimensions on a drawing but from the actual dimension of the aircraft. Link to comment Share on other sites More sharing options...
Flying Bozo Posted December 11, 2011 Author Report Share Posted December 11, 2011 Dick, So true. I think you are right at the heart of the issue. When they did the original W&B they must have used the actual measurements on that particular airplane. One other thing with my CT might be the tundra set up. The main gear would sit higher making the mandatory to have a slightly longer nose gear and the nose gear being at a forward angle would make that dimension longer...but wait... the dimension on my weight an balance for my plane is shorter than that listed in the operating instructions by almost 2 inches. So that blows that theory huh? I just can't believe that there is a 2 inch less dimension from the LE to the nose gear especially considering that my tundra option should make the nose gear axle farther from the LE rather than 2 inches closer. CONFUSED!! Larry Link to comment Share on other sites More sharing options...
Runtoeat Posted December 12, 2011 Report Share Posted December 12, 2011 Hi Larry. Now you've really got me with the 2" difference in dims for the front gear. Hmmmm. I also have the Tundra gear and recall that this has been beefed up compared to the standard gear. Seems that I recall reading that the engine mount is supposed to be different than the non-tundra mount. Could be that FD changed the geometry of the engine mount/front gear for the Tundra setup which might result in the 2" difference from the AOI? Or.......I could suggest that a previous owner may have set your plane down a little "hard" on it's nose during a landing and "tweaked" the gear?? Naw, don't even want to go there. :wacko: Â Roger Lee or Jeremy or Eric normally jump in and provide the answers to these mysterious questions we come up with but they've been pretty quiet. Link to comment Share on other sites More sharing options...
coppercity Posted December 12, 2011 Report Share Posted December 12, 2011 It is interesting. I would say the best thing to do is drop some plumb-bobs from the leading edges of your SW and measure the distance yourself and use those to calculate your WB. Link to comment Share on other sites More sharing options...
Flying Bozo Posted December 12, 2011 Author Report Share Posted December 12, 2011 Great idea, easy to do since there is such a huge difference in the numbers it should be easy to tell what is going on. I'll let you know what happens. Thanks Eric Larry Link to comment Share on other sites More sharing options...
Flying Bozo Posted December 12, 2011 Author Report Share Posted December 12, 2011 Dick (runtoeat) I appreciate your comments. The differences in the dimensions I am talking about are not actually measured by me so it is not a case of a hard landing somewhere in the plane's history. They are the actual numbers given for those dimensions in two places in the paperwork, one place on the actual weight and balance for this airplane and one place in the operators manual on weighing. The dimensions are nearly 2 inches different on the nose wheel to wing leading edge. Larry Link to comment Share on other sites More sharing options...
Roger Lee Posted December 12, 2011 Report Share Posted December 12, 2011 The POH is a general location most likely to all CT's since the POH is more universal and the actual W&B is the real deal for just your plane. I would rely on the real W&B and not worry about the POH. The W&B sheet is where they did the actual measurements and weighing. The POH is a standard issue for all of us. We discussed thew W&B verses the CG years ago. So long as you put weight where it is designed and don't stick Billy Bart up front solo or lead in the tail you almost can't get a CT out of CG. With all the W&B calculations done years ago by this forum there is no real issue.. Link to comment Share on other sites More sharing options...
Runtoeat Posted December 12, 2011 Report Share Posted December 12, 2011 Wow, there's all those guys after all. Thanks guys, I knew you'd give us some words of wisdom. I think that some of the long time members get a little weary of seeing issues that get recycled and beaten to death or new issues that get nitpicked to death. It is still good information for new owners or new pilots. Link to comment Share on other sites More sharing options...
Flying Bozo Posted December 12, 2011 Author Report Share Posted December 12, 2011 OK thanks for the input. I didn't know that all this was hashed over years ago. I agree with Roger, that unless you have a hippopotamus in the seat or some lead ingots in the back it is very difficult to get things outside of the loading diagram. Larry Link to comment Share on other sites More sharing options...
Roger Lee Posted December 12, 2011 Report Share Posted December 12, 2011 Having too much info at our hands whether it be in the books (old prints verses new printings) and lots of info from instruments like the Dynon we sometimes want to over analyse things and unless you can compare or relate it to other parts of the equation it can be easy to take them as a stand alone item and misinterpret its meaning. Everything needs to be looked at from a 360 point of view. All sides, top and bottom which means you have to analyse how it dove tails into other things and is it really telling me what I think it is. The one good example is the Dynon EMS D120. If you look at just one reading and not all of them it can be misleading. You need to look at the whole picture because if one thing is way out of the norm then some where something else should be affected. Someone called me the other day and was flying. The fuel pressure went in the red (low) and it scared him, but the plane never missed a beat and all other readings on the instrument were normal and the engine never once coughed. Bad sender. Fly the plane and look at the 360 picture and not a single reading. Â Â The less you analyse and work on your plane trying to pick at all the little things the less hassles you'll have and the more fun it will be. Â Well that said time to head out to the hanger and do a hose change and an annual. OH BOY! Link to comment Share on other sites More sharing options...
Flying Bozo Posted December 12, 2011 Author Report Share Posted December 12, 2011 OK thanks Roger. That hose change is you are doing is on a plane that I met yesterday in Havasu where we went for breakfast. His CT was there on the ramp so I walked over and discussed our mutual interest in the CTSW when he mentioned that he was on his way from Idaho to your place. Quite a trip. By the way, the next time you all fly out to Payson for breakfast if you could stand another CT to join you give me a heads up. Payson is a great place to meet up for breakfast and I only missed you by one day there. Larry Link to comment Share on other sites More sharing options...
Runtoeat Posted December 12, 2011 Report Share Posted December 12, 2011 Larry, I re-read my last post here and it sounded like I was complaining about your question. This is not the case. My intention was to give credit (in a backhanded way) to those long time members here who patiently put up with and continue to field the questions that may have already been hashed over which the new forum members ask. I consider myself a newer forum member since I'm a fairly new LSA pilot and CT owner who appreciates all of the postings here. The more questions posted, the better this forum becomes. A lot of the questions are ones I may have missed or most probably forgot because I can't keep it all in my feeble brain. Link to comment Share on other sites More sharing options...
Flying Bozo Posted December 12, 2011 Author Report Share Posted December 12, 2011 Dick, absolutely no offense taken. I am rather new to the forum (June 2010) and have read most of the old postings but have never seen anything about the dimensions to-from landing gear to leading edge. Also a search that I did on the forum on weight and balance turned up nothing relating to the subject at hand. Thus my posting asking for input on the subject. I guess I must have missed something because it sounded like there was an in depth conversation on the subject in the past, where I don't know. Larry Link to comment Share on other sites More sharing options...
Runtoeat Posted December 13, 2011 Report Share Posted December 13, 2011 Hi Larry. There are subjects that are not found here that have been discussed on a Flight Design forum which was in existence before this forum. The previous forum was very active and had many members. Many of the members here, including myself, were members of the previous forum. After the old forum was taken off the internet, I tried to go back and pull up some old information I was interested in but could not access this. I guess that the hundreds of posts, many with important information and data, are gone with no way to access them. Link to comment Share on other sites More sharing options...
mocfly Posted March 30, 2012 Report Share Posted March 30, 2012 Seems the ctflyer.com is back up Link to comment Share on other sites More sharing options...
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