FNG Newbie Alert! New LE Rebuilder

[Victor Bravo]

Greetings from Southern California,

I bought a single seat Legal Eagle from a guy in Oregon off of a Craigslist ad a few years ago. I gave a good friend of mine in AZ the opportunity to fix it up and get it flying (he had been my sailplane racing ground crew in the 1980's!) But it was too much work for him, he lost interest, and I stored it at his house for a year... and now it's coming back to SoCal for me to take a whack at putting it put back in the air.

I was privileged to have a phone conversation the other day with John Bolding, who was kind enough to share some wisdom, answers, ideas, and encouragement. He is a treasure to the aviation community!

This LE has a very low time full-case Casler half VW, so I am confident in the powerplant.

SEVERAL of the welded parts need to be replaced or re-welded. A few of the welds on the fuselage need to be re-melted. I have someone at my home airport that is qualified and equipped.

There MAY be one or two unofficial and undocumented modifications on this fuselage... he MAY have raised the wing mounting lug higher than stock. Anyone who can verify or de-bunk this please let me know, I'm trying to post a photo showing this.

The woodwork in the wing is a bit sloppy, but appears to be safe. Definitely not a showplane. I'll know more when I peel off the fabric.

There are some mechanical parts that need reworking or re-riveting, I can do that well enough.

The plywood wing leading edges are sagging inward, the original builder did not install foam false ribs. I MAY be able to install false ribs through the lightening holes in the shear web, that remains to be determined. I'd rather not remove the plywood and re-kit the wing.


Thanks for accepting me into the Eagler's Nest group, all advice, experience, etc. is welcome.

Bill in Los Angeles
Victor Bravo on Homebuiltairplanes.com and the Taylorcraft.org forum
(former) EZ Flap on Back Country Pilot forum
1956 Cessna 172
Based at KWHP San Fernando, CA

[CHARLES DEBOER]

Hi Bil, my name is Charles and I have been flying my LEXL at KCMA for 8 years.  I am in hangar #21.  Hope we can get together next Saturday, July 13 at 11:00 am for our monthly meeting.

[Victor Bravo]

Hi Charles, I have seen your aircraft once or twice when visiting KCMA! I was storing this one in Steve's hangar before it was taken from KCMA to Casa Grande AZ as shown in the photo above.

The meeting you mentioned.... is that the EAA Chapter 723 or the VCUA ultralight club? I may or may not be able to make it, don't know yet.

[Victor Bravo]

I got the Legal Eagle fuselage and wings unloaded from the trailer today and was able to look at the wing mounting. The original builder did something I'm not really happy with. I would like to solicit any opinions, advice, engineering knowledge, etc. from the group.

The original builder installed a 5 inch vertical tube on top of the main upper keel tube to raise the front wing mounting bolt higher. A slightly shorter vertical tube was added on the rear. He welded on some short pieces to "stabilize" the vertical tubes, but these only go part way up the wing mount tubes.

There is no gusset or steel plate support to prevent these vertical tubes from "swaying" side to side under load. This would quickly cause cracks and a total wing mount failure. I'm not any sort of engineer but I paid attention when my engineer friends talked... I really don't like this wing mount system! Does anyone else have this modification on their Legal Eagle?

Photos attached:

[CHARLES DEBOER]

Hi Charles, I have seen your aircraft once or twice when visiting KCMA! I was storing this one in Steve's hangar before it was taken from KCMA to Casa Grande AZ as shown in the photo above.
Normally VCUAS has the membership meeting on the first Saturday of every month but the holliday weekend  moves it to the second Saturday which will conflict with EAA normally held on second Saturday of every month.
The meeting you mentioned.... is that the EAA Chapter 723 or the VCUA ultralight club? I may or may not be able to make it, don't know yet.

[Chuck in Indiana]

I'm not an engineer, but am an A&P and an EAA tech counselor since the 80s.Here's my thought.
It's hard to tell from a picture, but to me it appears that there *may* have been a butt weld extension on the front mount. (!) Certainly the wallared out (Indiana technical term)  hole at the top is a no no.
If it were me, I'd hack saw it off just below the hole and have a look inside to see just what is going on before deciding how to repair it.

[Victor Bravo]

A retired Lockheed aero and flight test engineer looked at this wing mount today and didn't like it either. So at some point soon, I've got a hot date with a hacksaw and then another date with a welder.

The control stick and aileron control system was also not to my liking. I know that the loads are low, and I know that Leonard wanted to make weight, but there's stuff I just am not going to live with in this system. The aileron "arm" at the rear of the control torque tube sticks straight down under the airplane by 8 inches. Any weeds, brush, plants, etc. on the landing surface will impact and damage that setup. There's thin sheet aluminum and pop rivets that make up the base of the control stuck pivot. There's really thin steel strap bent at an angle into a cable connector, but the strap is loaded in off-axis bending by the elevator cable. I'm going to put a conventional aileron/elevator torque tube and pivot in.

Got some other ideas I'm gonna sketch out and see if they are viable, to simplify, reduce parts count, reduce weight, or make it more robust..

[Chuck in Indiana]

Your call, of course.. but I've not seen a push pull setup on a LE that I liked better than the simple and lighter cable/pulley arrangement. (shrug)

[Victor Bravo]

Well, I'm a little "old school" about primary controls. Secondary controls (throttle, mixture, trim, etc. I am a lot more willing to make sacrifices for cost or weight.

The plans-built control stick on this one has small steel tabs riveted onto the bottom of the stick where the elevator cable nicopress thimbles attach. The tabs have a 90 degree bend in them downstream of where they're riveted. The tabs are really thin as well. So normal elevator control loads pull on the tab, which puts a cyclic load on the bend, as well as putting the single rivet in 100% tension.

Another potential issue is the main aileron "arm" sticks down well below the fuselage, so any weeds, bushes, grass, etc. will try to bend it out of kilter and/or crack the arm. I am 100% aware that this is a high drag slow airplane, but that's not the kind of "drag" I'm worried about.

I'm looking into using the (Kolb style) horizontal aileron arm at the back of the aileron/stick torque tube, with vertical pushrods coming up behind the seat, actuating torque tubes for the ailerons. I can use fairly light weight materials for this, with a weight gain of a pound or so. There will be more weight removed from other areas than the weight which will be added.

A question I have for the group is whether the original "Tuffy" plastic bicycle wheels are robust enough for anything other than perfectly smooth runways. I would like to know if very many people have broken these wheels or not.

Another item is, after reviewing the plans, the upright fuselage tube for the forward spar mount on my airplane is almost 6 inches above the standard plans location. Has anyone else done this? Has anyone done engineering or load calculations on this? It's only the main wing mounting to the fuselage...

THANKS in advance to anyone/everyone for participating in this conversation

[Jeff XL79]

I would also like to use aileron torque tubes. I've never seen the Kolb system but it sounds simple enough. The kitfox lite also has a push pull cable system that look light.

Jeff

[Victor Bravo]

The Kolb system has rigid push-pull steel or aluminum tubes coming up vertically from the control torque tube. These attach directly to the inboard end of the aileron conrol horn which is riveted into the aileron leading edge tube (serving double duty as the aileron control torque tube). The diameter of the Kolb aileron leading edge is not sufficient for its length in my opinion, and the hinge axis is offset from the torque tube axis... a very clunky and friction-prone design. But thousands of Kolbs are flying so it is 'good enough'.

The system I am sketching out (not set in stone yet!) is about a 2 inch thin wall torque tube that runs just behind the rear main wing spar, through the space in the built-up ribs and through the one round hole in the plywood at the last full length wing rib. A nylon or Teflon bushing will support the tube at this plywood structure.

A riveted control horn (either a light 4130 weldment or a sheet metal riveted assembly) will come down vertically (through the fabric) from the outboard end of this tube, with a short push-pull tube to the aileron horn.

On the inboard end, a similar plywood plate and plastic bushing will support the inboard end of the torque tube, with a similar fabricated arm or horn extending rearward. This plywood support will be glued to the root rib. The vertical pushrods from the aileron control will actuate this control horn.

So the pilot moves the stick. This rotates the aileron control tube under the seat, which rotates the new horizontal aileron arm. The ends of the aileron arm move the rigid vertical pushrods up and down. The pushrods rotate the spanwise torque tubes inside the wing. The outboard horn on this tube rotates fore and aft, pushing or pulling the aileron control rod, which actuates the aileron.

The advantage if this is that it does NOT require any cable tension, which eliminates all built-in stresses or loads on ANY fastener, pulley, bellcrank, fairlead, and control stick. There are no cables to catch on any bushes. There is no 8 inch arm sticking down out of the fuselage.

[Kamcoman77]

An LEU builder made a modification to his fuselage that added some headroom and uses the XL, 2-bolt wing attach method. When we were setting his dihedral it was so much easier to install/remove the wings compared to the LEU single bolt setup.

[Chuck in Indiana]

VB, take a look at the Cub like controls on the XL. Still light, and gets rid of many of your (and my) concerns.

[Victor Bravo]

Thanks, does anyone have photos of the XL control system handy, for me to look at and compare to what I got? I only have LEU plan set O-53, which is really kinda marginal. I have R/C model airplane plans that are much more complete, detailed, etc. than these.

[Kamcoman77]

Should be quite a few photos in Chuck's Build Log. If you haven't looked through it, you should. It is very thorough.