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Nose gear fairing

B

burgessbuilderMO13

Active Member
Just started working on the nose gear fairing, and came to the steps where there is a hole drilled and tapped in the gear leg to secure the fairing. Really?
Has anyone done this, as it seems to me a good starting point for a stress riser in the making. Has anyone developed an alternative scheme to retain the fairing position. I am thinking of a fiberglass rib setup near the top of the leg where the bent is below the lower weldment.
Thanks for any ideas.
 
A length of Velcro along the leading edge of the gear leg would work a treat (still using the piano hinge at the rear of the fairing, with a cable tie securing the forward lower end. ;)

Well secured and personally, a preferred alternative to the hole drilling idea.

Note: we're in the UK so not restricted by US LSA regs.
 
The holes you are talking about get drilled right at the neutral axis of the nose gear leg load path (Google neutral axis for an explanation).

Because of this, the danger of the holes causing a problem are virtually zero.
 
It is very apparent that some 12's have been landed very, very hard and no one has reported a problem in this area? I had the same thought when I was building.
 
Doubting Thomas!

530 hours on mine and no problems.;) Who am I to believe the most successful Kit manufacture in the industry. Not! (Just some form humor):D
 
I thought about it for a while, but decided in the end to follow the plans. Predictably, and despite being careful I still managed to get one of the holes about 1/8" off the centreline, and I suspect I'm probably not the only one. It's not that easy to see exactly where the sweet spot on the leg is when it's obscured by the fairing. The other one was close enough to where it was intended to be. I did put them an inch apart rather than exactly opposite each other as a somewhat token gesture at further reducing any small detrimental effect they may have on the strength of the leg.
In looking at the geometry of the leg, it seemed to me that the holes have been carefully located at a point where bending stresses under landing loads will be smallest. That, and putting the holes on or very close to the neutral axis mean that stress changes due to bending adjacent to the holes will be minimal.
 
I, too, got one of the holes about 1/8" off center. The steel is very hard and the drill can wander if you are not very careful. It is a good idea to use new high quality drill bits from a good source and that goes for the tap as well. Proceed very slowly with the tap and back it out frequently to clean chips. I did not break a tap doing these holes but others have. Getting a broken tap out is not fun.
 
RFSchaller said:
I put it on because I built it ELSA, but it seems to be just a decorative piece of added weight.
Click to expand...

If you do a little research on the parasitic drag of different object shapes, you might be surprised to find that the bare nose gear leg could be more drag than the two main gear legs combined.

Not saying the gear legs make a lot of drag in the 115-120 kt range, but the goal was to make it a 120 kt airplane so a fairing was done for the one that produces the most.
 
Scott,

What did your in depth aerodynamic analysis determine as the added speed? Did it consider the vibration effects of vortex shedding?

Rich
 
RFSchaller said:
Scott,

What did your in depth aerodynamic analysis determine as the added speed? Did it consider the vibration effects of vortex shedding?

Rich
Click to expand...

Of course! The vortex shedding was found to be much more severe without the fairing installed.
I highly recommend that all RV-12 builders prop up my employee profit share... I mean avoid the excessive vortex shedding an purchase the optional fairing kit. :rolleyes:
 
Uh oh... did all you guys pick up on that? ..."vortex shedding reduced but obviously not entirely eliminated!! Now I'm going to be worried about residual vibration resulting in the nose wheel falling off. One more thing to lose sleep over. :(
 
Scott,

I was beginning to think you didn`t have a sense of humor! I am happy you proved me wrong! :D

Rich

BTW: Tower gave my 12 the best compliment ever yesterday when they asked me if I could accept a slower speed for traffic. I guess that nose fairing really works!
 
rgmwa said:
Uh oh... did all you guys pick up on that? ..."vortex shedding reduced but obviously not entirely eliminated!! Now I'm going to be worried about residual vibration resulting in the nose wheel falling off. One more thing to lose sleep over. :(
Click to expand...

I have been worried about this all along!
 
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