Josh and Pete's Lazair Project in Maine

Share your thoughts, photos and general help to all builders

Postby G-man » Sun Oct 10, 2004 9:08 pm

Hi Guys,
I've posted a website to chronicle the restoration of our Lazair and will try to keep up with it every step of the way.
www.gurleyauctions.com/lazair.html

Just some pictures so far but it will grow.

What can you guys tell me about this model? All I know is that its a series III.
Also, we have some covering material that I think is Mylar but having never handled Mylar or Tedlar I can't tell the difference. Just how Translucent is Tedlar in comparison? Whats on mine now?
I'm ordering the materials to make new ribs this week and plan to move right along with the project. Any suggestions would be greatly appreciated. Also, if there are any wing mods that have been incorporated and proven I'd love to know about them. I'd like to do a sharp trailing edge and some flaps but beside a few photos I cant find any real facts or plans for them. Any thoughts?
Thanks,
Josh
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Postby JPXman » Mon Oct 11, 2004 2:20 am

Looks like a solid project with not much damage!

For the ribs, don't cheap out on the filament tape - use a lot on the tip of the ribs, this is where they crack most often. The thinner the tape you can get, the better it will be, as the wider stuff "wrinkles" when you do the crossovers...

I found my "wing mod" list of stuff from the old lazairpilots group, so I'll post it here. I'm going to (among other things) begin a paper about these mods to collect them into one place for people just like you who are starting out. stay tuned, but for now, here's my download.....

1) Sharp trailing edge – get it and install it!

2) Doubler skin on D-cell from root to past engine mounts - do it!
Even if you have 0.020" skin...

3) "Long bolt" modification (to allow bolts to mount the engine to the
wing that go all the way through the D-cell, with the head on the top,
and a nut on the bottom, with compression tubes between the spar edges
to take the load rather than the edge of the spar itself)

4) Fibreglass wingtips - a must! The old ones can crack or be damaged
and you can't see inside the fabric, and have to disassemble the end of
the wing to replace. The fibreglass one sits outside your covering, and if it needs to be replaced can be popped off and replaced easily for $75US (email Mike McKusick)

5) Jury struts - and easy mod that increases the -ve G limit.

6) External capstrips - easy mod that only requires extra 1/2" double
sided tape, rivets and some capstrips (this mod is done after the wing is covered)

7) Aileron rib/spar reinforcer - I have found that on each of the 4 wings I have rebuilt and covered with tedlar, that the rib where the aileron spar attaches too cracks and bends right at the attach point. A simple aluminum "false-rib" riveted to the top and bottom capstrips of that rib, opposite the spar, about 4" above and below the attach point greatly increases the strength of this rib

8) Rib attach bracket – a mod that must be done with the rib out of the wing, as you must rivet a U-channel of aluminum to the nose of each rib, with 1” sides to the U. Then, once the ribs are reinstalled, an L-bracket is riveted from the sparweb to this U-channel. This simple mod eliminates all movement of the rib relative to the D-cell, alleviating the wing gussets job of taking these loads.

9) Sparbox corner smoothing mod – in just about every lazair, the topside of the wing right at the corner of the sparbox at the rear wing attach fitting, the covering is always exposed to a “pressure point”. This mod simply adds a piece of smooth aluminum from this corner to the root rib, and with a bit of sanding this piece becomes smooth and takes away the “point load” on the covering here

10) Root rib stiffener – Ultraflight mod used on the Elite and 2-seater to accommodate heavier engines/flight loads

11) Kick spar – for the totally obsessed with wing strength, a spar that runs from the outboard strut attach point to the rear wing spar attach point. This spar would absorb any loads exerted on the wingtip in a “ding” situation and transfer the load to the fuse tube rather than crushing the sparbox.

12) Spoilers – I have seen two lazairs with spoilers incorporated into the wings – very classy

13) Flaps – I have only seen one lazair with flaps, and it looked like a big job…
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Postby G-man » Mon Oct 11, 2004 7:06 pm

Thanks JPXman,
Thats just what I needed to know. I'd like to incorporate as many as those mods as possible. Many of them I can understand perfectly. Some of them are harder to visualize. If you can help me along with these mods I'd be happy to keep a photo record of each one for the forum. Previous to what you've told me I could only find bits of info and references.I wonder what all that modification weighs and if it would become an issue?

Forget my questions about Mylar and Tedlar. I have enough Mylar to cover one wing (maybe) and its seamed down the middle. Doesn't seem right. Im going to order my tedlar from John Nagy tommorrow.

One more thing for now... I read about how the nose ribs can move around in the D-cell so I started poking it to find them. I found the aluminum quite loosely formed around them. especially on the flat bottom. In many places the skin was 3/16" from the nose rib. Is this normal? One D-cell has quite a bit of damage. It was also skinned with 3 pieces and doesnt match the other. I wondered if a D-cell can be re-skinned and if anyone has ever attempted it?
Thanks again.
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Postby Chappy » Tue Oct 12, 2004 12:19 pm

Josh,

You mention that you have a Series III. Unless you are planning on installing large, heavy engines, try to haul very heavy pilots, or some other extraordinary mission, I doubt that many of these modifications are appropriate. I will make my comments below. Please know that these are just my opinions. Most of my experience has been with the most popular models, but I worked at the factory during the development of both the 2 place and Elite models, which included some test pilot work.

(From JPXman's comments. I hope I don't piss off Tyler with my comments!)

For the ribs, don't cheap out on the filament tape - use a lot on the tip of the ribs, this is where they crack most often. The thinner the tape you can get, the better it will be, as the wider stuff "wrinkles" when you do the crossovers...

< This is very good advice. >

1) Sharp trailing edge – get it and install it!

< Adds weight and complexity, strengthens the trailing edge so that it resists bowing in when covering is shrunk. Also allows covering to be more easily over shrunk because you lose the visual indication of the tailing edge being pulled in excessively. Over shrunk Tedlar covering will not allow the tapes to perform well over an extended period of time. May cause a little less drag - giving you an almost measurable increase in cruise speeds. >

2) Doubler skin on D-cell from root to past engine mounts - do it!
Even if you have 0.020" skin...

< Adds weight, shouldn't be required unless you decide to "Upgrade" engines or install reduction drives on the Rotax 185's. >

3) "Long bolt" modification (to allow bolts to mount the engine to the
wing that go all the way through the D-cell, with the head on the top,
and a nut on the bottom, with compression tubes between the spar edges
to take the load rather than the edge of the spar itself)

< Good, long term mod. for all Lazairs. >

4) Fiberglass wingtips - a must! The old ones can crack or be damaged
and you can't see inside the fabric, and have to disassemble the end of
the wing to replace. The fibreglass one sits outside your covering, and if it needs to be replaced can be popped off and replaced easily for $75US (email Mike McKusick)

< Adds weight and expense. Appropriate, I guess, if you have a hangar buddy that keeps banging you wing tips into the door opening every time he moves your plane. >

5) Jury struts - and easy mod that increases the -ve G limit.

< Absolutely do this. >

6) External capstrips - easy mod that only requires extra 1/2" double
sided tape, rivets and some capstrips (this mod is done after the wing is covered)

< This is only required as a band-aid fix if your wing covering (usually associated with Tedlar) become loose from the ribs. This is usually caused by overheating the tapes while shrinking the covering. Adds weight. >

7) Aileron rib/spar reinforcer - I have found that on each of the 4 wings I have rebuilt and covered with Tedlar, that the rib where the aileron spar attaches too cracks and bends right at the attach point. A simple aluminum "false-rib" riveted to the top and bottom capstrips of that rib, opposite the spar, about 4" above and below the attach point greatly increases the strength of this rib

< Good modification for all models. >

8) Rib attach bracket – a mod that must be done with the rib out of the wing, as you must rivet a U-channel of aluminum to the nose of each rib, with 1” sides to the U. Then, once the ribs are reinstalled, an L-bracket is riveted from the sparweb to this U-channel. This simple mod eliminates all movement of the rib relative to the D-cell, alleviating the wing gussets job of taking these loads.

< The wing gussets were designed to take these loads to the reinforced top and bottom surfaces of the spare. The spar web was not designed to handle these loads! Adds weight, cost, complexity, uncertainty. If, for some reason this was a problem that needed addressing, a larger gusset would surely be more appropriate. >

9) Sparbox corner smoothing mod – in just about every lazair, the topside of the wing right at the corner of the sparbox at the rear wing attach fitting, the covering is always exposed to a “pressure point”. This mod simply adds a piece of smooth aluminum from this corner to the root rib, and with a bit of sanding this piece becomes smooth and takes away the “point load” on the covering here

< Nice thing to do. >

10) Root rib stiffener – Ultraflight mod used on the Elite and 2-seater to accommodate heavier engines/flight loads

< Adds weight. Again, not needed for normal satisfactory operations of a Series III. >

11) Kick spar – for the totally obsessed with wing strength, a spar that runs from the outboard strut attach point to the rear wing spar attach point. This spar would absorb any loads exerted on the wingtip in a “ding” situation and transfer the load to the fuse tube rather than crushing the sparbox.

<Adds weight and complexity. Stop running into trees while taxing. >

12) Spoilers – I have seen two lazairs with spoilers incorporated into the wings – very classy

< Adds weight and complexity. Could be a cool addition if done well, dangerous if not. Not required for flight control, as a very proficient Lazair pilot will learn to use precise speed control to control sink rates. >

13) Flaps – I have only seen one lazair with flaps, and it looked like a big job…

< Adds lots of weight and complexity. Total waste of effort, not required. Use the time saved in screwing around with this by spending it flying your Lazair as much as you can! >

< Also, concerning nose ribs: >

One more thing for now... I read about how the nose ribs can move around in the D-cell so I started poking it to find them. I found the aluminum quite loosely formed around them. especially on the flat bottom. In many places the skin was 3/16" from the nose rib. Is this normal? One D-cell has quite a bit of damage. It was also skinned with 3 pieces and doesnt match the other. I wondered if a D-cell can be re-skinned and if anyone has ever attempted it?

< The problem with nose ribs coming loose and falling over inside the D-spar was mostly confined to the first fifty Lazairs produced. I was the first customer to bring this problem to Ultraflight's attention. Later Lazairs were built a little differently to reduce this problem. Mounting heavy engines, and having accidents can cause this problem in newer Lazairs. You can certainly re-skin the spars, but it is a little difficult to get the tight fit to the nose ribs that Ultraflight did because of their investment in a specially designed fixture they used. You could build one too, or just use a whole bunch of nylon straps to pull it up into position. You will need to put a gentle 90 degrees bend at the appropriate place in the material before you do it.

If you want to keep this from happening in a good wing, remove the rivets along the bottom of the spar, lift up the skin and apply a bead of adhesive RTV a couple inches long on the bottom of each rib next to the spar. Then immediately pull the skin back into position and re-rivet. Obviously, this requires recovering the wings.

Like I said, these are only my opinions. Actually, I've seen lots of other mods done to Lazairs in the name of improvements. Most only added weight, which has the dual bad affects of simultaneously weakening the overall airframe and reducing performance. Watch the Weight!

Chappy, Lazair #25 >
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Postby G-man » Tue Oct 12, 2004 1:52 pm

Thanks Chappy,
I agree with your assessments for the most part. I would like to use a redrive eventually so probably some strengthening is a good idea. My Trailing edge had a very pronounced bat-wing shape from an over zealous shrinker so initially I was quite excited about the sharp edge mod. Then I read that 1/16" indicates proper shrinkage and I see that its not a necessary mod, but I'm sure it looks nice.

From what I've read Dale Kramer himself was interested in improving performace, bringing up the power to weght ratio, and strengthening the airframe. So I think that its actually quite appropriate to see all of this experimentation. I've read some pretty harsh opinions about various individual's mods in the forums. Personally, I would be thankfull to anyone who's willing to explore the possibilities and share there experiences. Especially at such great risk. All the speculation in the world is just that till someone just plain does it. Kramer didnt have Autocad in 1978. My guess is that he built it, tested it, flew it, and if it didn't work he built it again. Guys like that are the reason that guys like me can build and fly a safe airplane! Whether or not any of these mods are improvements, they are bound to teach us more about our individual Laizairs, stock or modified.

Mostly, I believe if it isnt broke dont fix it. But improvements are improvements so if anyone else has any opinions or experiences with these wing mods I would love to hear about them so I can make an informed decision on how to proceed.

Chappy,
But what about my D-cells? I dont think the nose ribs have moved, but there is excessive slop in the skin that concerns me. I assume they are made that way. The aluminum didnt just expand by itself? No adhesive seems to have been used? Can I assume that my D-cells are safe?

What about an additional .016 covering skin from root to washout? Takes care of the dents and re-enforces the nacelles.

Thanks
G-man
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Postby JPXman » Tue Oct 12, 2004 4:14 pm

Hey Chappy, no harm no foul! point and counterpoint are required in the design process.

As a data point, my series III is running JPX engines, and I am 6' 7" and 290 pounds :) My main lazair concern is structural integrity, as the JPX's more than make up for the ~20 pounds of extra aluminum in my wings. But, that is just my lazair. If you are not as girthy as I am, you probably don't need all these mods, but if you forsee down the road adding larger engines, and you're recovering, they are indeed something to consider. I also expect to be flying off floats at some point in time, so my empty weight may go as high as 350 pounds! then with me in it I'm almost at 700 pounds. I figure that if my wings are built to 2-seater specs, they should be able to handle 750 pounds of load (what the 2-seater is rated to).

Yep, these are just a compilation of mods, not a REQUIRED UPDATE list :) Pick and choose what you want from it.

Tyler
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Postby Guest » Wed Oct 13, 2004 10:47 am

Plane is pretty well tore up. This is going to be big job so don't under-estimate the challenge. What condition is the fuselage. Any bent tubing. How do you plan to deal with the corrosion ? What about the engines, what condition are they ?

Any more pictures. One picture came up as a Chest of Drawers. Good for storing misc parts I guess.

Plane has small rudder pushrods. That may be a good upgrade item.

Overall you have something to work with but this will take time and plenty moolaa. If you can do it you will have a unique, fun, and safe plane you can operate for cheap. Well worth the effort.

I would not worry about knowing every little detail just yet. You can get help as you go. If you can take lots of pictures people here can help you decide what to do on the different things.
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Postby Chappy » Thu Oct 14, 2004 11:29 am

<<Hey Chappy, no harm no foul! point and counterpoint are required in the design process.

As a data point, my series III is running JPX engines, and I am 6' 7" and 290 pounds ...>>


Wow, Tyler, now I AM glad I didn't make you mad!

I see why you are so interested in structural upgrades, although for someone your size and weight converting a two place Lazair into a big single might make more sense in the long run - assuming you could find one when you want one. How comfortable are you when your flying? I would think you would be awfully tight in there! Even if you could fit into my old small Series 1, I doubt you could get out of ground effect in it!

I agree with the comments made here too about upgrading to the larger, straight push-pull rods to the ruddervators. I've seen too many nylon parts dry out and crack over the years to really trust them, and they operate with less friction and wear. I feel the same way about the nylon plugs used in the push rods in earlier Lazairs. The strongest plane probably won't save you if the control system becomes compromised.

Chappy
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Postby JPXman » Thu Oct 14, 2004 4:33 pm

When you are in my frame, you abandon thoughts of comfort at a young age :) Cars, motorcycles, bicycles, aircraft, if you can't put up with tight spaces life would suck. In the lazair, its tight, sure, but its really not that bad! I'll send some pics when i get the series III back in the air.

I actually own a 2-place, and its like flying a cadillac compared to the single seater. A lot more leg, shoulder and head room (more head room because the fuselage tube isn't right over your head).

...and just installed a groovy new control stick to help not having the stick hit my legs. So, I figure with beefed up wings a-la 2-place on the series III, I should be good to go for years to come. now if only i could lose 50 pounds...

Tyler
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