On 10/10/2021 10:33 AM, Ryan wrote:
In this test it looks like the upper spar cap broke because the shear web
failed.
http://www.krnet.org/mvn2008/080921265.jpg
My KR2 comes in at 633# empty. So that makes it 153# overweight to start with.
What is the new wing with the larger spar caps that you mention?
Is the KR2S wing spars different than the original like I have?
Ryan
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Spar caps are not stressed vertically but horizontally. When the wing
is loaded the upper spar cap is stressed in compression and the lower
spar cap is stressed in tension, hence the shear web failing
horizontally between the two.
My target empty weight was 650 #'s but I came in at 765 # and there are
heavier then mine flying. That does not justify building to that spec
but simply to say yours is one of the lighter one completed lately.
As to the new wing, if you are not familiar with the new wing then you
are about 10 years behind on the latest KR info. Someone please post
the links to all the new wing info for those not familiar. If your KR
is complete with the RAF48 airfoil don't consider going back and
rebuilding the wing for the extra 10 mph claimed. That will only keep
you from flying sooner.
On the "153# overweight", the 480 pound KR2 that Ken build is not a
stake in the ground that can't be passed. The KR is a very robust
design and you simply need to consider how the extra weight will affect
your KR both in structure and performance. Many of the recently
finished awesome KR's go well past the 700# mark. Just know and accept
the limitations and penalties of the extra weight.
To my knowledge the 2S spars are the same as the standard 2. It is the
new airfoil that may or may not change the spars depending on the exact
build you chose. Someone will give you links to a week or two worth of
reading.
Larry Flesner
________________________________
-Please see LIST RULES and KRnet info at http://www.krnet.org/info.html
-Change list delivery options at
https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info Board
-Search recent KRnet Archives at
https://list.krnet.org/empathy/list/krnet.list.krnet.org/
-Search John Bouyea's decades of archive at
https://www.mail-archive.com/krnet@list.krnet.org/
