Thermalling

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Postby lazairiii » Wed Mar 18, 2009 5:30 pm

They are absolutely worth it. They offer an additional negative G-load. I don't recall exact numbers (Shannon?).

I had a recent flight where I was going up 1000+ a miunte then dropping like a rock then back up again in thermal weather and each time my helmet smacked the main tube as the plane would instantly decent, I was so greatful I had the negative g's in my favor. Not once did I even conside the struts could fold in that wild ride. True story...
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Postby mochamon » Wed Mar 18, 2009 5:52 pm

well considering I plan on soaring my bird, I think it is a must. Thank you.

where can I find plans to install them?

what size tubing? length? where is is bolted on the wing? etc.

Thanks again :D
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Postby Shannon » Wed Mar 18, 2009 6:41 pm

On a light Series II you are looking at nearly 1-G negative gain.

The factory numbers for the increase in negative load factor are here.
http://www.lazair.com/files/Lazair%20Jury%...izer%20kit1.pdf

The construction diagrams for the needed parts are at the bottom of the Jury Strut info pages.

http://www.lazair.com/files/
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Postby ozzie » Wed Mar 18, 2009 10:38 pm

I was lucky with adding the jury strut mod to my lazair. when i found mine it came with a box of spares and it had a brand new jury strut kit amongst them. most of the parts are easy to make if you have a small folder the harder parts are the strut mounts. if you are going to do the jury struts i really recommend that you do the rear spar box and end rib strenthening mod as well as the doubleing of the strut attach fitting on the wing this will give you a couple of more G's . search the 3 lazair groups, the drawings are there somewhere
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Postby mochamon » Thu Mar 19, 2009 1:56 pm

well, this turned into quite the job. lol. well worth it though. I suppose yo can't reinforce the rear spar box and end ribs without having to recover the wings can you? if not it will have to be a winter time project next year. Still get to fly in the good air this year though.

thanks again, you guys rock.
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Postby ozzie » Thu Mar 19, 2009 11:08 pm

you can just remove the covering on the underside of the panel you have to work on. maybe you can source some mylar or tedlar to recover from someone local. when you recover you can run two stripes of 1/2 inch double sided tape over the rib side by side then put the mylar on and then finish it with 2 inch tape on top it wll hold ok. it will take only a few hours to do both wings once you have the parts
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Postby Shannon » Fri Mar 20, 2009 10:10 am

Ozzie I think it's a good idea to explore using the 1" wide 3M VHB F9469PC double sided tape vs. the 1/2" wide tape when recovering with Tedlar. On my last recovering job I went with the 1" all around vs. using the 1/2" and it worked super especially with the Carlson sharp trailing edge. We are talking about double the holding surface area with 1" wide double sided tape for a little extra cost.

Note *** People not using Carlson sharp trailing edge "may" need the 3M F9469PC 1/2" double sided tape on the original tube trailing edges***

I also highly advise using capstrips on ribs when splicing in bays. Additionally some folks in the past put down silver 1" 3M-850 (S-10242SIL) tape over each rib (under the capstrips) to give a UV protective component for the underlying double sided foam rib tape.

Note: At no time ever have I seen factory made capstrips placed "bevel down" or homemade "flat" capstrips cause cuts in Tedlar covering. I'm talking about many years and multiple planes with either flat or bevel down capstrips installed.

Pic: "Bevel down" capstrip on rib with underlying ~ 1-1/4 to 1-1/2" run of Tedlar tape over covering. Celus Alum/Alum mandrel-head rivet placed on 3" spacing.
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Postby Shannon » Fri Mar 20, 2009 11:51 am

mochamon @ Mar 19 2009, 01:56 PM wrote: well, this turned into quite the job. lol. well worth it though. I suppose yo can't reinforce the rear spar box and end ribs without having to recover the wings can you?  if not it will have to be a winter time project next year. Still get to fly in the good air this year though.

thanks again, you guys rock.


Lee I personally would not open up the wings to make modifications unless:

#1 The covering was bad and needed changing.

#2 The existing original type engine mount nutplates were stripped out.

#3 I was ready to do "complete" wing upgrades which for me would possibly include Box section stiffeners, Compression Tube Motor Mounts (with improved motor mount pads), R-8 rib doubler, and front wing attach fitting doubler along with some other minor mods (R-3 rib mod ect).

The Jury strut upgrade IS something you can do without having to strip covering from the wings. The Jury struts with wing attach fitting doublers give great piece of mind as well as improve strength.

Pic: George's plane during assembly. With the enlarged image you will spot the Box section stiffeners, Compression Tube motor mounts with improved motor mount plates, and front wing attach fitting doubler.
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Postby mochamon » Mon Mar 23, 2009 3:37 pm

Hey Guys,

Glad to hear I don't have to recover the wings to do the jury struts. I will do that mid summer after I feel much more comfortable flying in the calm weather. My wings are not covered with the typical Tedlar, it is actually covered with shrink wrap. The same stuff used at marinas to store boats. Apparently it is easier to recover the wing, and much cheaper. It also holds up incredibly well in regards to UV.

Anybody gonna have theirs ready for April??? :)
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Postby ozzie » Tue Mar 24, 2009 3:10 am

the forward wing mount doubler, does anyong have a good photo of this?
is it a factory mod. i have not seen reference to it in upgrade.

i just use the 1/2 inch tape as i have a few spare rolls for emergencies. i had thought of useing 1 inch there are some areas it would work better than the 1/2 inch. i use the VHB on the ribs 1 inch but as the ribs bevell away from the covering only half of it maks contact with the covering.but no need for the cap strips yet. there is a pattern maker upstairs and he uses a mylar sheet about a 64th thick to trace out patterns for cutting materials this looks like it would make great ribcaps.
had no problems recovering one bay only. i run the first strip of half inch double with an edge clearance of at least 1/4 inch from the edge of the rib.

got any photos of your cling wrap wing covering?
as usual great tips from you guys.
just gota get me a series 3 lazair and ship it here or maybe just ship me there :D

i coped an earful off the 'missus' when i showed her the adverts for 900 dollar airfares to LAX. oh well maybe they will still be discounting next year.
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