Scaling aircraft....watch out...

[John_Cillis 2,406]

This post is not meant to slight Kittyhawk in any way--I am going to use it as an example of something that I've done and many designers have done--and I wanted to post a warning so designers are aware of it when trying to get their aircraft in the right "scale" for various projects.A while back, someone had noted that Kittyhawk's 737-700 seemed oversized. I couldn't tell, since it is hard to know unless you have something to compare it to. So that's what I did...I created a "yardstick" in GMAX the exact length of the 737-700. And the Kittyhawk model was indeed too long, and now I know exactly why.When a mfg gives a length measurement for an aircraft, simply put it is the aircraft measured from the foremost to the aftmost portion of the aircraft. What many have done is measure from the foremost portion of the aircraft to the aftmost portion of the fuse. Sorry to say, you end up with an aircraft which is oversized. And, if you are scaling according to a three view, it will be oversized in the length and height dimensions in the mimimum, and possibly in width depending on the project.I have a screenprint below of the issue. Again, this is not to take a jab at Kittyhawk's work. I can't do anything close to that quality and that's why my last bit of work--updating Byron Warwick's Jabiru--was just that--my last project. The arrows just seem to fly too hot and heavy at freeware authors these days for it to be worth the effort. That's one reason why I am posting it here--since this is where the designers hang out. Perhaps someone can benefit from the knowledge.To explain the screenshot, the 737-700 has a length of 109 feet, seven inches. My "yardstick" has the same length. It matches perfectly from the foremost to aftmost points of the fuse--but the aftmost portion of the horz stab should have been used for the measurement...-Johnhttp://forums.avsim.net/user_files/80928.jpg

[n4gix 4,947]

Although I haven't seen the Kittyhawk 737 myself, I am very much aware that what you've stated is true. For each of the models I've built, I've been lucky enough to have engineering drawings to work from, and have noted from the beginning that the fore/aft measurement is as you've described.Thanks for bringing the issue to the table for everyone to learn from!

[Guest Erick_Cantu]

That's odd. It matches all my Boeing documentation, then again, the conversion to metres probably accounts for that...even then it's a small difference so I don't really mind...you win some you lose some, right? ;)Either that, or the length difference is due to the fact that the original nsoe was lengthened. Originally it was too short!The problems were amazingly bad on the -600 and -900 though, because the documentation on them is so scarce...I think the -900 might be either too long or too short, but, meh...it's close enough.

[Hornit 3]

I tend to agree with Eric here, while its great to be really, really accurate, i think asthetics are important and while it may be off a tad, it looks fine in the sim to me. John, you have a good point though and it's something future modelers should take into account. I had wondered about this in the past, as some modelers claim thier measurements are flawless, derived from manufacturers specs, but the model is still obviously not right.Hornit

[ejoiner 21]

Hey Hornit.Im the guy who made the original notation that the -700 looked too big. I love the AeroMexico livery in that plane, and after a great flight I pulled up to the gate next to several AI B737s. The Kittyhawk plane looked much bigger. Now Im no modeller, so coulda been the AI, but as JohnCi notes there was/is a problem with that airplane. Hey, freeware and its a good one...but it did look odd to me.Eric