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Shortened wingtips

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Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 5:36 am Post subject: Shortened wingtips

Finally forced myself to do this.  Step one, layup 5 layers of cloth or tape on the taped off old tip, cover with peel ply and let cure.  That gives a great starting point for the mounting flange.  If you're not making them removable, skip that step...but you need some flange to mount to the wing.  The black lines on the white wingtip are my alignment lines to make the flanges.



Once that was done, I measured out 18" from the inboard end of the tip, which is almost exactly where the tip begins it's upsweep into the winglet, and cut off the tip and winglet.



That tip will be much shorter than the end of the wing, so you'll have to split it and mount the two halves to get started, which can be see in the second picture.  The flange I made in step one is inside the wing end, and I've already bonded the new tip to that flange.



I'll make a separate post for each pic from now on.

Last edited by Bill Strahan on Thu Oct 04, 2012 5:57 am; edited 1 time in total

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 5:40 am Post subject: Re: Shortened wingtips

Once the tip is bonded to the flange, make sure it's aligned with aileron and drill and cleco the flange in existing mounting holes.  Then fill that big gap with some foam and prepare to get artistic.  This tip was the one I tried to do the first time about 2 years ago, which is why it's so mangled. I decided it was easier to cut off the parts I was unhappy with previously, so there's more foam here than on the other tip.



Yes, I'm using cheap insulation foam.  It doesn't really matter since it's A) not structural and B) not going to stay there!

Last edited by Bill Strahan on Thu Oct 04, 2012 6:00 am; edited 1 time in total

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 5:43 am Post subject: Re: Shortened wingtips

From the previous pic, the foam had a flat spot, so I added a bit more foam and then sanded to this final shape.

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 5:45 am Post subject: Re: Shortened wingtips

2 layers of glass over the foam, showing the Right wingtip now, just happens that's the one I took the picture of.

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 5:48 am Post subject: Re: Shortened wingtips

A quick shot, showing the original long tip (yellow) in foreground, the new shortened tip on the plane, and following that diagonal line, the long tip from which the short tip was chopped off sitting on the table on the back wall.

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 5:51 am Post subject: Re: Shortened wingtips

The best thing I can say about this is:  Wear a dust mask, use 36 grit sand paper, take a shower the moment you're done.



This pretty close to a final shape.  There's some waviness, but overall I'm getting happy with it at this point.

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 5:55 am Post subject: Re: Shortened wingtips

Between the last picture and this picture, I tore out the foam from inside the tips, sanded down to glass, and put in a layer of glass on the inside.  I final drilled the mounting holes while the tip was held in with clecos, and then installed nutplates.  The closeout rib was the last step, and the tip was ready to fit, as seen in this picture.



I only put a screw in every other hole because I still have to take them back off to put the nav lights on.  But this was good enough for a flight this morning once I taped over the hole the nav lights go in.

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 6:14 am Post subject: Re: Shortened wingtips

While countersinking holes for rivets on the nutplates, I accidentally countersunk one of the holes for the screws.  It was a nice mistake, because it's often a pain to get these screws started since the holes don't line up perfectly until several screws are in to pull it into shape.  So I lightly countersunk the screw holes and they go right in.  Always nice to learn a new trick when doing this stuff.



As to the flight, it was delightful.  I don't have any of my landing gear cleanup on right now, and I was happy with the speeds.  It wasn't a big difference, but definitely faster.  The bigger difference was in roll rate and control harmony.  I REALLY like roll now.  I've had the rounded wingtips on this plane as well, and this feels the same in roll to me.  And now pitch and roll forces are MUCH more in line at anything below 130 knots or so.  Once you get much over that  speed, the roll still gets pretty stiff, but it takes less deflection with these tips to get the roll you need.



Which also means my autopilot is happier.  It's sometimes bumpy where I fly, and at times the autopilot servo clutch is slipping when large corrections are needed.  I had a nice layer at 1800' today while testing that was bumpy as could be.  Wind speed was shifting direction about 90 degrees and going from 8 to 36 knots in about 1000 feet, so some big diversions were guaranteed.  Autopilot worked noticeably better based on my experience in that type of thrown-against-the-belts flying.



I'm happy.  But, if I'm not happy I can always take these off and put the old tips back on.



If you aren't restricted by LSA requirements, I highly recommend considering this mod.  I didn't do a full stall exploration on today's flight, but decided I'd add 5 knots to all speeds in the pattern until I examined it in detail.  Clearly too much based on how long I landed, so I'm guessing the stall speed is at most a 2-3 knot increase when using 30 degrees flaps.  Makes sense to me since most of the lift is coming from the large inboard wing with the flaps extended.  I'm sure it's a bigger increase clean.

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Thu Oct 04, 2012 6:19 am Post subject: Re: Shortened wingtips

Oh, one last thing.  My hangar just got 3 feet wider!

J Dupont

Joined: 19 Mar 2008
Posts: 26

Posted: Fri Oct 05, 2012 5:52 am Post subject: Re: Shortened wingtips

Very nice work, these look great.

geather

Joined: 06 Feb 2008
Posts: 23
Location: Mt Hutton Australia

Posted: Fri Oct 05, 2012 6:27 pm Post subject: Shortened wingtips

Bill,

I must have missed your first post on this topic and am a little confused!!

Did you shorten your LSA wings or did you add wing tips to the Experimental model?

If you shortened the LSA version - was there a reason for doing so?

Thanks



Geoff eather (Kit 127) Australia

On 04/10/2012, at 11:55 PM, Bill Strahan wrote:



 	  Quote: 	
		   

 

 Between the last picture and this picture, I tore out the foam from inside the tips, sanded down to glass, and put in a layer of glass on the inside.  I final drilled the mounting holes while the tip was held in with clecos, and then installed nutplates.  The closeout rib was the last step, and the tip was ready to fit, as seen in this picture.

 

 I only put a screw in every other hole because I still have to take them back off to put the nav lights on.  But this was good enough for a flight this morning once I taped over the hole the nav lights go in.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=384625#384625

 

 

 

 

 Attachments: 

 

 http://forums.matronics.com//files/img_2260_137.jpg

_________________
ge

Bill Strahan

Joined: 20 Aug 2008
Posts: 145

Posted: Fri Oct 05, 2012 8:03 pm Post subject: Re: Shortened wingtips

Geoff:  N197RW is an Experimental, not LSA.  I believe I hold the record for most wingtips installed.  Right Nick?  I had the long wingtips mounted with piano hinge.  Those were removed and a set of short wingtips were mounted the same way.  Those were removed and a different set of long wingtips were mounted with #8 screws.  That long set was removed, and I took the first long set and fabricated the short tips shown in the pictures above.



So at this point 7RW has had 4 different sets of wingtips.  If someone has had more than that, I'm going to fabricate some modified Hoerner tips and some flat (Mooney style) tips and mount those just so I can claim the record.

geather

Joined: 06 Feb 2008
Posts: 23
Location: Mt Hutton Australia

Posted: Fri Oct 05, 2012 8:53 pm Post subject: Shortened wingtips

Bill,



Thanks for that. 

Any difference in performance with the different wing tips?



Geoff Eather (Kit 127)

On 06/10/2012, at 2:03 PM, Bill Strahan wrote:



 	  Quote: 	
		   

 

 Geoff:  N197RW is an Experimental, not LSA.  I believe I hold the record for most wingtips installed.  Right Nick?  I had the long wingtips mounted with piano hinge.  Those were removed and a set of short wingtips were mounted the same way.  Those were removed and a different set of long wingtips were mounted with #8 screws.  That long set was removed, and I took the first long set and fabricated the short tips shown in the pictures above.

 

 So at this point 7RW has had 4 different sets of wingtips.  If someone has had more than that, I'm going to fabricate some modified Hoerner tips and some flat (Mooney style) tips and mount those just so I can claim the record.  

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=384767#384767

_________________
ge

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