Page 4 of 5

PostPosted: Thu Mar 20, 2008 8:05 am
by Shannon
Fairly typical looking damage for the accident you describe. Half way between the inboard wing attach fitting (boom) and the wing strut attach fitting is usually where the wing likes to bend and distort. The weight of the engine in that "unsupported" area is what helps produce a twisting-bending-crinkling moment. On the other hand if a plane hits one wing first damage will often be from the outboard strut attach fitting out to the tip. The R-8 can bend and the box section will crumple-accordian as the wing pushes rearward. Spar twisting and buckling can also be present.

What I fear is you could have other damage that you have not discovered yet. Often the wingtip structure (rib, tabs, and tube) gets damaged/bent and the box section(s) deform or crack.

It's hard to judge from just one picture the scope of the damage. It's all together possible you could open the wing and peen out the skin damage. Being that the D-cells are painted you could cover remaining ripples with body filler and prime/paint over the area. Replace a bay or two of covering and the plane is back in action.

Personally I'd look at this as a possible opportunity to refurbish the plane in a fairly comprehensive way. Again personally I would be thinking about upgrading a few items and opening up the wings to refurbish all the nose ribs ... #entry6384 . Fixed and with new covering the plane will be good to go for years to come.

The pic is one of the D-cells I refurbished a few years back. With the enlarged image you can see the minor denting and rippling in the skin around the engine mount area.

PostPosted: Thu Mar 20, 2008 8:45 am
by Shannon
Wingtip rib "flip over" damage

PostPosted: Thu Mar 20, 2008 9:27 am
by JPXman
i agree! the first lazair i rebuilt i was pretty tentative, and opening up the D-cell completely seemed like a daunting task.

but when you break it down, if you can remove a rivet without enlarging the hole that's pretty much the only skill you need - you just have to do it 1000 times!

putting it back together is pretty straightforward, and takes 2 people, some good styrofoam industrial glue, a case of beer and a box of cleco's. but once its put back together its as good as the day it left the factory. cut out the bad sections of aluminum and replace with splicers with 2 rows of rivets down each side of the splice if you don't want to replace the whole leading edge skin.

keeping the old skin as much as possible keeps the job really easy as all the old holes are already drilled and lined up. putting on a whole new skin requires the construction of a jig to hold everything together tightly while the glue on the noseribs dries and you can drill a few holes to get some cleco's in to hold the skin to the sparweb.

its not a hard job, nor a big job - it just seems that way because the part is 18' long.


PostPosted: Fri Mar 21, 2008 6:42 am
by mickbroom
Thank god for this group and all you guys and the information.
There is nobody in the UK with the collective experiance and hours on the plane that you have so I cannot ask. Hopefully with your help I can achieve two things, get two Lazairs ( My mate has a bent one as well) back in the air and fly safely for a few more years to show the fans what a nice plane it is.
I am happier with the information on the leading edge and am in the position of about to remove the leading edge skin which I have been approaching very slowly wondering what I had taken on and if I was up to the job. With your comments I will go for it in a more confident manner and see what we can find. I am warming to double skinning the panels under the motor after I have repaired the skin but will look for any other damage first.
Thanks and have a good weekend - gales and rain with a little snow coming here so no flying just working in the shed

PostPosted: Sat Mar 29, 2008 2:24 pm
by Shannon
The only other custom assembly I'm aware of that strengthens the F-9 is on Karl's Series II. This is the only picture I have found of his assembly. It looks to be a 2-part bracket with one part being attached to the boom and extending upward to the wing attach fittings. Riveted to this is a bracket similar to the "F-9 doubler" on my plane.

The assembly also serves the secondary purpose of holding in place his compass and tachometers.

PostPosted: Mon Mar 31, 2008 5:43 am
by mickbroom
Neat idea.
I like the idea of putting the compass and stuff up under the wing.
Sort of justifies the extra bracket if you can use it for other things as well.
Are the extra tubes a series II thing?

PostPosted: Mon Mar 31, 2008 7:26 am
by uscgairdale
The tubes look to be part of the framework for the windshield and pod.


PostPosted: Mon Mar 31, 2008 7:42 am
by Shannon
Correct, the tubes you see are supporting the Lexan windshield.

PostPosted: Mon Mar 31, 2008 8:47 pm
by flyalaz
Hi Guys,

Long time since I've had time! I still don't know how often I'll be able to put my two cents in. My younger son was diagnosed with Leukemia seven months ago, and we have been putting everything we have into this fight. He had a bone marrow transplant a week ago, and so far things are looking good. There is a long road ahead but we have faith that things will turn out well.

Here is a shot of the pod alone, showing how it goes on. Two holes at top slide over the upper tube you saw in the previous pic and are held in place with a couple of lengths of lock wire, and three bolts per side on the bottom lock it in. easy on / off arrangement.

PostPosted: Tue Apr 01, 2008 5:47 am
by mickbroom
Very sorry to hear about your son, tell him we are thinking of him in the UK and I hope he gets better soon. Someone will need to fly dad's plane when he is bigger.
Nice screen but I think the weight problem I have will not allow me to fit one so its back to spitting out flies for me. <_<