Measuring Wingspan

Twisted Sheets · Nov 06, 2009, 06:22 PM

I am building what is supposed to be, an 8 inch wingspan FF glider. The three pieces of the wing are actually almost 9", but because of the angle they are supposed to be attached at (dihedral), it measures 8.5 inches, tip to tip.

If I want an even 8", do I angle up more on the tips, or cut off 1/4 of each center section of the wing, or shorten the tips.

Such a simple little plane. So many questions.

I am assuming that wingspan is measured from tip to tip?

JonSayre · Nov 06, 2009, 07:06 PM

I would remove a 1/4" from the tip joints. If you are building from plan I'm sure the dihedral has more or less already been optimized so adding more may(or may not?) decrease performance. Lets see some pics, FF gliders rock!

glenn2626 · Nov 06, 2009, 07:09 PM

Print yourself up a slightly shrunken tape measure like thing that "you use all the time" and use that to measure when you take it to your next competition.!!!

Ok, so honestly, I'd like to know the proper answer that's why I'm essentially subscribing to this thread now...

Glenn

Ian Easton · Nov 10, 2009, 01:04 PM

If you want to cheat you better do it right and enlarge the ruler!

BMatthews · Nov 10, 2009, 02:17 PM

Either option would be fine. But it would look cleaner if you trim from the center line joint. On the other hand trimming off a bit of the tip would retain more wing area. And I agree that you should not change the dihedral angles. That would have far more implications than just trimming away a little bit of wing area.

Another option would be to run the plans through a photocopier and shrink them by a couple of percent to get to the final span.

The resultant span after the dihedral is added is refferred to in model circles as the "projected" span since it's the span as "seen" if you look down from above or up from below. Sort of like projecting a shadow and measuring the span of the shadow.

Nov 06, 2009, 06:22 PM	#1
Twisted Sheets Registered User Join Date: Sep 2006 Posts: 58	Measuring Wingspan I am building what is supposed to be, an 8 inch wingspan FF glider. The three pieces of the wing are actually almost 9", but because of the angle they are supposed to be attached at (dihedral), it measures 8.5 inches, tip to tip. If I want an even 8", do I angle up more on the tips, or cut off 1/4 of each center section of the wing, or shorten the tips. Such a simple little plane. So many questions. I am assuming that wingspan is measured from tip to tip?

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Nov 06, 2009, 07:06 PM	#2
JonSayre Registered User Join Date: Apr 2009 Posts: 66	I would remove a 1/4" from the tip joints. If you are building from plan I'm sure the dihedral has more or less already been optimized so adding more may(or may not?) decrease performance. Lets see some pics, FF gliders rock!

Nov 06, 2009, 07:09 PM	#3
glenn2626 gnu bee Join Date: Jan 2008 Location: Colorado Springs, CO Posts: 408	Print yourself up a slightly shrunken tape measure like thing that "you use all the time" and use that to measure when you take it to your next competition.!!! Ok, so honestly, I'd like to know the proper answer that's why I'm essentially subscribing to this thread now... Glenn

Nov 10, 2009, 01:04 PM	#4
Ian Easton Registered User Join Date: May 1999 Location: riverside, ca,usa Posts: 2,444	If you want to cheat you better do it right and enlarge the ruler!

Nov 10, 2009, 02:17 PM	#5
BMatthews B for Bruce Join Date: Oct 2002 Location: Vancouver BC Canada Posts: 4,683	Either option would be fine. But it would look cleaner if you trim from the center line joint. On the other hand trimming off a bit of the tip would retain more wing area. And I agree that you should not change the dihedral angles. That would have far more implications than just trimming away a little bit of wing area. Another option would be to run the plans through a photocopier and shrink them by a couple of percent to get to the final span. The resultant span after the dihedral is added is refferred to in model circles as the "projected" span since it's the span as "seen" if you look down from above or up from below. Sort of like projecting a shadow and measuring the span of the shadow.