LSA140 Build

[Bdflies]

Well, now I'm even more impressed. They cut and finish each of those tubes manually! That explains why they fit the tubes into a jig.
This is what I was talking about; https://m.youtube.com/watch?v=azaJsnbbH9c
That thing would spit out each tube, perfectly cut, in about 10 minutes, if that. But then, it takes a bunch of volume, to pay for these beasts!

Bill

[lsa140]

That is very cool, thanks for sharing.

[lsa140]

Only a few pieces of tubing left in the stack. I still need to tack on a temp tail post and put on a few more tubes in the tail, but other than that everything is tacked.

[Chris In Milwaukee]

Super straight!

[lsa140]

Thanks Chris, looking forward to seeing that XL fuselage come together.

[lsa140]

*Note: Deviation from plans. Changes to the LSA shown here have not been approved by the designer. I will be making a few modifications to the cockpit area for my specific mission. One of those changes is to the rear seat. From the stock position it will be adjustable: 4-5" forward, 2" lower - 2" higher, the seat base incline will adjust, and the seat back recline angle. The seat will not span the entire width of the rear fuselage. The frame will be around 19" wide. I need to be able to remove, fold, and stow it in the baggage area. Additional structure will be added from station B to D. (similar to the changes incorporated into the Patrol in 2014, in this same area.) The aircraft will be used extensively off airport. The purpose of these mods will be to strengthen the gear and float attach areas, as well as increase the cockpits ability to resist deformation in a crash. A very close eye is being kept on retaining the light weight of the LSA. The photos bellow show a truss that I designed and tacked together today. It serves a multiple roles: 1. Strengthen the float attach area. 2. Provide more rigidity and support to the 3/4"x 035 tube that runs vertically to the rear wing spar attach. 3. Provide an attach point for two vertically adjustable seat supports. 4. Provide a tie down point and barrier to keep cargo strapped down and away from the rear stick when the passenger seat is out. I made and drilled two telescoping seat supports, jigged, and tack welded them to station D. The bottom portion of these will be removed when the welding is finished on the rest of the truss. I cut most of the way through, half way up the supports. This will allow easy removal later. The jig was removed, and the remaining truss tubes were fitted and tacked. I also found a tapered 3/8 nozzle online, with a tapered contact tip for my little 135 welder. It works great, and makes getting into clusters for tacking much easier.

[Chris In Milwaukee]

I like the height adjustment. Cool for kids who like to see!

[lsa140]

I want my wife to be sitting as high as the overhead clearance allows and comfortable. I also need to be able to drop the seat all the way to the floor for someone my height. No need for a fancy panel or interior, but the seats need to be just right.

[lsa140]

*Note: Deviation from plans. Changes to the LSA shown here have not been approved by the designer.

Cut and assembled the additional side cabin truss assembly. The diagonal tube that runs across opposite the door has been omitted. (it was cut up and used for the truss) The diagonal in the side truss runs opposite of the Patrol, which I believe would be more ideal, but I want to utilize as much of the original LSA tubing kit as possible.

Some small pieces of plated where added, sandwiching the seat adjustment tube socket. I wanted a little more structure to carry loads through that area than just a short piece of tubing with holes. With some good welds, the area should be sufficient for its purpose.

Approximate weight gain:
Station D truss: 1.25 lbs
Cabin side truss: 1.25 lbs (almost half of the tubing came from the omitted diagonal)

There will likely be additional weight added with the adjustable seats and dual doors, though I am considering some ways to keep those items very light.

[Bdflies]

Excuse my question, but I feel the need to ask; have you done some testing, of TIG welding over your MIG tacks? I can't state, without some reservation, that I recall problems with such, but I absolutely recall problems involving MIG fill passes, over some specific SMAW tacks. The problems were caused by high levels of de-oxidizers, in the stick electrode, not being well tolerated by the MIG fillermetal. Granted, this was a fairly specific application, but one that was puzzling and unexpected. Be sure to 'qualify' your specific TIG process (including your specific fillermetal), over your specific MIG tack process.
The last thing I want to do, is unecessarily stir up a mess. But I don't want to ignore something that could present an issue.

Bill

[lsa140]

I have, thanks for the question and heads up. It is a common practice for this application. I'm running ER70 wire and filler rod. Everything fuses nicely.

http://youtu.be/5qvN6HGoAkQ

[Chris In Milwaukee]

That's great to know. I have an unused MIG looking for something to do :-)

[lsa140]

Chris In Milwaukee
​I prefer tacking with TIG, but trying to bend over and reach across the build table through a tubing maze at difficult angles to place a little tack gets old quick. If I was going for a perfect looking final weld I would slow down and strictly use TIG for tacking, but my goal is a balance between production and quality. Everything will be TIG welded once on the rotisserie. .023 wire with a 3/8 nozzle on a small gun seems to work well on the wire feed. I have a little 110v Northern Industrial 135 wire feed that I paid $165 new. Wrestling a large gun with 035 wire would be a disaster, getting setup specifically for tacking is worth the effort.

[Chris In Milwaukee]

Thanks for the tip. I have a Hobart 140 (similar class of machine). I plan to torch weld mine. But the quick-attach of the MIG will certainly go faster (and cooler).

[lsa140]

Sounds like a good plan. What type of torch do you use?

[Chris In Milwaukee]

I have a Meco Midget that I plan to use, but I'm sure I could be talked into TIG easily :-)

[lsa140]

This afternoon as I was cleaning up around the shop I got distracted by the tacked fuselage sitting nicely on the table and started thinking through cockpit layout. Pretty soon I was sitting on blocks and trying the pilot and passenger positions on for size. As I sat in the front seat, I realized there was a large volume of space above the rudder pedals, and under the instrument panel. This evening I pulled up some build photos of another LSA with the boot cowl off/instruments installed, and sure enough there is quite a bit of free space. (even with the instruments/etc installed.)

Playing around in CAD, I came up with this forward fuselage storage box. It would not be accessible in flight, and there would be a latch on either side to insure the door would not have any chance of coming open at the wrong time and interfering the pilots legs or controls. It would be TIG welded out of aluminum and hang from several tabs welded to the airframe. The door would face the pilot and hinge down against a stop, resting parallel to the bottom of the storage box.

It would be lined with some light weight padding or carpet to keep contents from rattling around with the engine vibration. Depending on your CG, you could utilize the space for small heavy items, possible tools and survival items. I could see a tool wrap, pistol, etc. Lighter survival items would be tucked away in the rear baggage (sleeping bag, tarp, etc)

The usable space would be around 27" wide, 6" tall, and 12" deep. Plenty of room would be left for legs and feet. You could possibly leave the two front upper corner cut out to be able to inspect the upper engine mount bolts, or leave it back far enough to lay under the panel and look up in front of the box. It would be easy enough to remove as well.

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[Chris In Milwaukee]

Certainly a nice place for logs, maps, manuals, and other things used between flights. Cool and creative use of space!

Off topic, what are you using for CAD? I'm getting started with Autodesk Inventor to document my project.

[lsa140]

Thanks Chris. I use and highly recommend http://moi3d.com and http://www.rhino3d.com. Think of MOI as a 3d sketchbook, it is by far my favorite piece of software. The two programs use the same native file type (3dm). Ideas take shape in MOI and Rhino has more powerful CAD functions, plugins, and complimentary programs.

[lsa140]

Finished final tacking the fuselage this afternoon. Put in a short temporary tail post, the full length tail post will go in after the rest of the frame is welded and off the rotisserie. I have a two month job at a remote site starting this week, and am having a hard time putting the project down. There is building, and there is funding the build... both are required. It will be a good opportunity to finish designing the seats and cockpit layout.

I've been really pleased with this little Porter Cable PTX2 die grinder. A 1/16" x 3" cut off wheel comes in handy for cutting or grinding tacks. The little 3/4" sanding drum worked well for fine tuning the tail post fit. The 2" fine scotchbrite spin on wheels work great for cleaning tubing ends. The 2" flapper grinding disk removes material quickly. For most standard garage fab projects a 4" electric grinder is the go to tool, for aircraft work this little die grinder is the ticket. I wish I had purchased one sooner.

[sbmurphey]

Looking great!! Keep up the good work. I can relate to taking time off the build. I have a roof project kicking off in a couple weeks. The tubing kit went together quick and it is addictive watching the rapid progress.

[lsa140]

Thanks Stephen! I'm appreciative to you and BTAZ for posting your build experiences. It helped me decide on purchasing the tubing kit, and how to go about putting it together. I hope you project is coming along well, and the roof goes quick.

[lsa140]

I've been out of town working long shifts, and haven't been able to physically work on the plane. It has provided an opportunity to research and plan for upcoming purchases/work.

Here is what the LSA looks like on 27.5" Desser Aero Classic Tundra Tires, and the Bearhawk Tundra Tailwheel.

Screen%20Shot%202016-03-21%20at%205.50.09%20PM_zpsi7f7e1mf.PNG

[lsa140]

Here are a couple threads regarding the 27 Desser. Sounds like they are less draggy than the 26" airstreaks.

http://www.teamkitfox.com/Forums/sho...?t=5512&page=4

http://wingsforum.com/viewtopic.php?f=218&t=23668

I think this would be an excellent setup for they type if flying I'll be doing: (27" desser. 8" matco double caliper.)

[lsa140]

*Note: Deviation from plans. Changes to the LSA shown here have not been approved by the designer.

Some tubing aft of station G-K had been previously been left out. (diagonals and tail spring socket tubing/supports) I hadn't yet decided what type of tail spring I was going to install. After some thought, I've decided to go with the LSA/Patrol round tapered tail spring. The tubing kit came with 1 x 058 socket and 1-1/8 x 049 outer reinforcement tube. There was a little slop in the fit. I'd prefer the reinforcement tube to rest directly against the socket tube. A scrap piece of 1-1/8 x 058 fit snug around the socket, so I cut out a new piece and welded the two tubes. This also gives me a little more metal to support the spring and retaining bolt. I believe the Patrol uses the thicker 058 reinforcement tube as well.

I have a temporary short tail post in place until rotisserie welding is finished. I won't be tacking all of the tubing around the tail spring mount at one time. Some pieces will be welded together on the bench, others will be tacked on at a time and fully welded. That area has some difficult places to reach with all of the tubes in place.

Here is the high temp infrared gun I found on amazon. It reads up over 2,000 degrees and was a little under $100. I haven't used it much yet, but look forward getting some time with it.

http://www.amazon.com/Taotuo-Non-con...irect=true&amp ;ref_=oh_aui_detailpage_o02_s00

[lsa140]

*Note: Deviation from plans. Changes to the LSA shown here have not been approved by the designer.

Decided to attach the full length tail post to make welding that area easier. Adding one tube at a time and stopping to fully weld everything possible before placing the next tube. The tail area has some tight spaces, and this method is making it easier to get good welds.

Preheating with a propane torch to around 300-400 degrees. Bumped the wall thickness of the tail post to 049. This is absolutely not needed, I just wanted a little more metal in that area for my specific mission. I've added around 12 ounces of weight to the tail. The tundra tailwheel is a little heavier as well. This will help offset the extra 20lbs+ of bush tires up front.

I beveled the bottom edge of the tail post, exposing the 3/4 liner. I'll use a very sharp tip on the TIG electrode and walk in a nice full bead to fuse everything together. I preheated the tail post/liner and used the wire feed for the rosette welds. I much prefer the TIG for most applications, but once in a while a circumstance comes up that the MIG is well suited for. The Northern Industrial 135 welder I bought years back runs smooth at a very low heat setting/wire speed. The 3/8" nozzle with tapered tips are coming in very handy.

[lsa140]

Continued to add tubes, and weld up the tail spring attach cluster. Even with adding one tube at a time and welding, those inside corners are really difficult to weld! It made me wish I had one of the tiny low clearance specialty TIG torches.

The remaining tube that runs from the front of the sprint socket to the tail post needs to be tacked and welded.