building a wag aero 2+2/ upgraded pa14

Hit a milestone today in my opinion, I completed the upper half of my fuselage.

I fit the 1/2" tubes left long and cut them once i had the bends done.




Here's a trick I use cutting tubing when you need the cuts to line up, I have a bunch of them center finder's that go on scales that I got in an ebay lot, so I just superglue one to the tube and use a level on it. they hold pretty well and you don't have to worry about the saw vibration creeping the location of the tool like something that clamps on.




the top firewall tube in place and the 1/2 tubes cut to fit.



here's how I did the joint, according to the drawings all the firewall tube's are cut on a 45 so I did that and I wanted the 1/2" tubes to connect at the middle of the joint so it looks like this for the time being. I will need to work the cope of the 1/2" tube on the bottom to fit the vertical firewall tube afterwards.



that wrapped up the upper half



I then flipped it and tacked up the bottom of the joints pretty good.

I also finish welded the 3/4 to 1/2 join, I'm happy with how it came out.



then I hung up this half and cleaned off the table, I sanded my lines off with some 320 sand paper rather then painting the table, I hate the smell of burning paint....

I got some progress made on the lower section the last 2 days. once again deciphering the drawings took some time on a few locations.

I got my Jig's built and used this crude setup to string the datum line to make sure on some things. not stable but it worked and lasted long enough to get the few measurements I needed.



last night I finished up with the rear longeron sections blocked in place and the center and front just rough cut and laid in place.



today I bent the liners and got the rest of the longerons in place.





I have the longerons fitted to the bottom firewall tube But I havent cut it and wont be tacking it until I join the upper and lower halves so I know its in the right location and the 45* cut is in the right orientation.



Then to finish off today I rough cut all my diagonals and cross tube and laid them in place, tomorrow will be the fun of coping 30 tube ends.



Also if anyone is quarantined or just wants something to watch, I do have a youtube channel that I have been doing videos of this plane build on as well, plus I have lots of other vids of diesel stuff, machining and other shop stuff. If you want to see that the channel name is Labrador Iron.

Looks good, Labrador Cub.

I got a kick out of having your table run through your car lift. That's what I was doing, too. I actually gave a little thought to setting the table on it to lift and lower, but abandoned the thought.

believe me it crossed my mind as well! I want to use the table later on to build the wings so my plan is while I have the fuselage on the rotisserie to pick the table up with the lift and just leave it in the air. killer is it will block my center row of lights so if it ends up to dark under it I will put the table outside.

I love my car lift. Versatile as hell. Sometimes I even use it to work on cars.

finished up the lower section today, went pretty good I'm learning lots about coping tubing and each one is going quicker.

the rear half was much like the top section.



up front was much more interesting having so many different tube size's and having 2 diagonal tubes in some bays.



Argo somehow sleeps through me cutting tubing with a chop saw and and coping the ends with a angle grinder and die grinder.



Here's the lower half all fitted and tacked.



I'm also getting quite a collection of templates

started the part I was not looking forward to because I know others had trouble here, and I ran into trouble due to lack of info in the drawings in my opinion and I've heard the jigs wont work if built per the drawings and I believe it, I wish the plans had the measurements between the upper and lower but there's nothing really, lots of measurements from the datum to the lower section ( which I cant get to match up either, plans say all measurements are C to C and when I measure like that its way off but if I measure to table its really close) so If anyone has any insight on this I'd appreciate the help!

so I built the bulkheads as per the plans dimensions and laid on the top half, looked good until I started comparing it to the drawings.



here on the drawings of the jig it shows the datum passing through the second bulkhead



and then on the page with the fuselage side view it shows the rear door post cluster is below the datum. also note the lack of measurements of all the side tubing and between the upper and lower longerons.



But in my situation the line is well below the second bulkhead and below the door post location ( you can see the heat bend in this location)



next discrepancy is at the tail, on the fuselage drawing its show's 3.5" from lower longeron to datum ( where I have the line located) then 7.75" from datum to upper longeron.



I built the last bulkhead as per the drawings but it places the longerons at 8" above the datum.



also my upper wants to sit with this cross tube behind the 4th bulkhead but looking at Marty's build his is in front, if i put mine in front it moves my firewall top tube to far forward but I'm thinking if I bend my longeron down at the door post so its below my datum that might bring it back in spec.



any Info here would be great! I don't want to go bending stuff just to see and it end up having to go back.

OK. I remember that confusion. One thing to look closely at is that bulkhead #4 has (I think) a 1 1/16 slot on the bottom. All the others in the middle are 3/4 slots. I scratched my head on that until I ran a straight edge on lower longeron on the profile view. I noticed a bend up toward the back. Things started to fit when I saw that. The lower longeron has to bend up a little there.

Same thing with the PA 18 drawings. The lower longerons bend up there, too. Studying those is what caused me to look at how all that should fit.

Thanks rv, I do have the upwards bend in the lower and I guess the upper will have a slight bend as well to the tail post. with the upper longeron laid in relaxed there is a Gap at bulkhead #4, That's why I have my hand in the last picture pressing down. I also have the bigger notch in bulkhead #5 you were talking about.

Sorry, I hadn't read closely. I don't think I bent the upper longeron. I'd have to look--it's in the rafters right now.

I do remember thinking I wanted the tailpost to be perpendicular to the datum and attached at the right places. So I fiddled with the bulkhead locations to achieve that.

My previous boatbuilding practice took over: follow the profile and plan views of the finished project and be suspicious of pre-made jigs. If there is a discrepancy in the main drawings, use a fairing batten to work out the difference.

BTW, I went back and looked at my build thread to jog my memory. It looks like I gave up on using the #5 jig and just let things flow to get the right end result. The jig set up was frustrating.

https://www.supercub.org/forum/showthread.php?53240-Therapy-Project&p=715123&viewfull=1#post715123

Thanks again Rv ,took the day off from the plane to clean the house and cook a pot of chilli but of course it was on my mind and i think I have a plan. the firewall is 90* to the datum as well as the tail post. I'm going to try stringing the datum separate from the bulkheads so when I move one of the ends it doesn't move that, I know where the firewall has to be in reference to the datum as well as the bottom structure so I will set the front bulkhead, after that when I lay in the upper section it should be correct fore and aft, after i'll line up the tail post where it has to be which is also at a 90* and I have the dimensions for its locations. I'll play with the center of the upper longerons till it looks close, realistically as long as the tail and firewall are correct and I attach the upper structure in the right place the plane should fly fine. I don't mind if my upper longerons at the door post are 1/8" off from a factory pa14, after all I'm scratch building everything so it will all be built o fit

Here's the biggest hint I can give you from my build. Purchase a factory engine mount before welding the lugs for the firewall. I didn't do that ..... big mistake. I jigged everything real good but when I tried a factory mount, it didn't fit! I had to have one custom made. I welded everything else but the engine mount was way to difficult for me. If you use a factory mount as your jig, all will be good later on.
Marty

You clearly have put a lot of thought into this project and are making good progress, doing a great job. I have never built a fuselage from scratch and do recognize the amount of work involved. I have a question. Why did you choose to build the top and bottom first, then fill in the side tubes? If it had been me, I would have built the identical flat sides first then filled in the cross members. The vertical tail post would have been the last piece to be parallel to the firewall and to fix the accuracy and alignment of the length. Maybe it's a left and right brain thing, nothing more?

This is only a question on my part not a criticism. Perhaps I'm all wet? Keep up the good work.

Sky, the easy answer to your question is because the plans are set out that way: build both the bottom assembly and top assemblies flat according to the dimensions given, and then install the top above the bottom.

The rationale is that the upper longeron assembly is wider than the lower. If you built the sides flat, the ends would bow in as you spread it apart unless you accounted for the change.

Interestingly, the Wagabond is laid out how you suggest. That's because it is more square sided.

The pa18s are built doing the side profile and connecting the middle, I think you could do it with a 12 as well the sides are fairly Parallel on them to , but with how intricate it was doing the bottom section on this on I’m not sure I’d want sides in my way as well. I’ll have to build an 18 or j3 next and see what’s easier I guess haha

well I think I'm getting somewhere with this, first I set my firewall in the right place and on the right angle so it was square with the datum. I used a scrap of wood and a machinist jack to set the angle





I then set bulkhead #5 so the upper longerons to meet the tail post at the correct height



as you can see the longerons are above bulkhead #4 , I found bulkhead 4 is correct to set the longeron at the right distance from the datum, this is where the jack screw is located so its location is important.



I used a strap to keep the longeron in place here.



the I started to set bulkhead 2 and 3.



according the the drawing the upper longeron is straight from 4-7



so I ran a string from bulkhead 5 to 2 so it continued the plane i set between bulkhead 4 and 5 as they are known correct. this put the upper longeron at station 4 way below the datum and was obviously not right.



so then I looked around the plans more and on the page that shows the stringers and door opening trim I found a 11 7/8 measurement and using dividers set to that span I found the rear door post is twice that from outside to outside on the longerons. so I set bulkhead #2 to achieve that 23.75" at the door post location and then set #3 where it seemed happy.




so at this point I have a datum line located correctly , a firewall at 90* to the datum and correct for and aft, a tail post location also at 90* to datum , the front horizontal stab location at right distance from datum line and a rear door post that should be the right size. would i be wrong in saying any variation I have now from a factory pa14 is basically cosmetics? If I'm forgetting anything or there's a concern please let me know I'll be welding in tubes in the next day or two.

Joey.

Joey, it looks like you are zeroing in on it. I used a similar procedure. One thing I always noted was that Station #4 (not bulkhead 4) was exactly on the datum in profile view. Once the firewall was set up and tailpost located, I tried to make sure that the center of the cross brace on Station 4 was on the datum.

I found myself locating the datum string 1" higher than shown on the plans to clear that cross tube, and then being very sure to adjust the measurements to the adjusted datum string. After firewall, station 4, and tailpost are located, I could simply run a string from the center of that station 4 cross brace to the tail post and maintain a nice datum for reference along the tail section.

But...As you weld, (you likely know this) things move. So it goes.

managed to get the upper in the same view as the drawings today.

First I moved back bulkhead #2 so its at station 4, I then set the height to the datum line.



doing so put the door opening tube below datum like the drawings show.



I then set bulkhead 3 so it kept the longerons straight.



looking at the drawings ahead of station 4 of the upper longeron is bent upwards, during the build this section was flat on the table, I added a heat bend ( which will get cut out after ) and this looked much better !





looking at it now it looks much better then yesterday, I need to go back and do some fine leveling and centering again and the firewall bulkhead moved a touch to so I'll address that.

I would also suggest having your engine mount before you finish the firewall engine mounts. I made mine exactly as specified in the drawings and found the mount didn’t fit correctly because one leg of the mount was slightly out of plane. If you are building your own mount then that may not be an issue for you.

Thanks Jimbo, marty pointed that out as well, hopefully I have an engine mount before I am ready to paint the frame but if not I will make a pretty stout jig by welding up a frame and drilling the holes in my milling machine, should be all straight and square that way.

spent another 2.5 hrs messing with the alignment and could not for the life of me get the tailpost in a good place while still being square with datum, turns out I marked out the last station an inch short after I figured that out things made more sense of course.

What I cant make sense is these blueprints in general, I'm happy with the location of the upper in relation to the datum ( with the limited measurements from datum to upper) but other then the diagonal between station 7 lower to 6 upper the rest are off, even the one going from station 5 lower to 4 upper is listed as 24" but to get that station to meet the datum its 23" , what's even stranger on the cut list for that tube its saying 24" as well but I've found so far the cut list is 1 to 1.5" longer then the fitted tube so maybe that's a typo (if so is my second one I've found). even when checking the datum to lower longeron measurements ,depending on the station, sometimes I get the right measurement going to the tube center and other times I have to go inside or outside of the tube.

basically I've found 3 options while joining the top and bottom:
1. is build the bulkhead jigs like wag shows lay the upper half on like i did first and start welding in tubes, you'll have a strange creation of a plane none the less.
2. go by the measurement's shown in the station view, judging by the variance I have from my measurements to what they show you'll get some wavy upper longerons as well.
3. run the datum, square the firewall to it , set station 4 at datum height, set jack screw/ front vertical tower location correct from datum and set tail post correct distance from tower location and square to datum. and make the rest look correct.

switched gears again, and making this even more confusing! sorry to those trying to follow along But my brain don't stop and when something doesn't add up or make sense I'll go to hell and back trying to figure it out.

I"m starting to think someone just sat back and drew what looked like a fuselage and went back after and wrote in the dimensions. messing around with a dial caliper and doing some math every measurement I physically take on the plans ends up with a different ratio compared to the written dimension.

then I went even simpler and did this. set my divider to the 20 1/8 at fire wall.



then compared it the the 20 3/16 mid fuselage, thats the largest 1/16" I've seen!


then down the the lower longerons, same thing here somehow 20 1/8 is longer then 21 1/8.



I can see if I was going from page to page doing this but I'm staying within one drawing and finding big differences, on another page I found an 8" dimension that drawn significantly bigger then a 10" dimension again in the same structure. so I'm giving up on comparing to the picture and just using the bare numbers written down, if they are like me they can read a tape measure much better then drawing a picture, at least I hope so!

so for my fuselage height I'm using these dimension's and I hope this is my final decision haha.

I don't think the drawings are very accurately drawn. I follow the dimensions, except where it was obviously wrong, and used the dimensions of the jigs. When everything was tacked in place, the few PMA'd parts I was using all fit exactly as they were supposed to fit. The 20-1/2" measurement upfront is center lug to center lug for the engine mount, not tube to tube height. I never tried to use a divider to check the drawings, too many issues for that to work. When you layout the front connection tubes for the firewall, you must have an engine mount to use as a jig or you will hit the same wall I did . That is more critical than the dimensions you are concerned with in the pictures.
Marty

Thanks Marty I do have the firewall set to the proper height I was just using the 20 1/8 to show the drawings are way out of wack. it and the tail being in the right place is all im overly concerned about being as correct as possible and I have them locked in pretty good, I've just been playing with the middle trying to wrap my head around whats going on for my own satisfaction. I'm same way doing mechanic work just changing a part and fixing something isn't good enough for me I want to understand why it fixed the problem and why it failed in the first place.

Sure enough, Joey. I never presumed the plans were accurate to scale, myself. That probably came from building boats using only offsets.

Ideally, you could loft things full size using real measurements. Or you could draw it out with an engineer's or architect's scale at some reduced ratio to see how it lays out.

Or you could go with the measurements given, since they seem to more or less work.

The other complaint I had with the plans was how often they used measurements between points instead of references to a fixed point. Talk about propagation of error! What I did in most cases was pencil in dimensions to either the datum or firewall, or other fixed point, just for my own sanity.

I gave up documenting things like this, but I thought there might be a market for some revised plans.

I don't have a Piper PA14 drawing anymore but I have a bare PA12 fuselage. If you need any tube centers I can measure for you. Except for the wider front bay for the front seats there is almost no difference in the two fuselages. The 2+2 prototype was built like a stand off scale RC model. Wagner used a set of PA12 wings on it. Except for the wood ribs the plans built wings utilize J3 wood wing steel parts with a few mods for gross weight increase. Lots of them have been built and probably no two alike. Seems to be quite a few in Canada. When you are done you will have a well built new fuselage with all 4130 instead of a 72 year old relic that when you cut out a tube to replace you pour out powdered rust.

labrador_cub said:

.

I"m starting to think someone just sat back and drew what looked like a fuselage and went back after and wrote in the dimensions. messing around with a dial caliper and doing some math every measurement I physically take on the plans ends up with a different ratio compared to the written dimension.
]

Click to expand...

There a ton of truth in that. Cubs are diffrent lengths. Maules are Inches different than the prints. Don’t get hung up on prints. The only important thing is stabilizer travel in relation to level flight as far as tail goes.

I have pa-12 prints. Maybe-14? I’m not at shop anymore today. Remind me if you need a picture of a section of it.


Sent from my iPhone using SuperCub.Org mobile app

mike mcs repair said:

There a ton of truth in that. Cubs are diffrent lengths.

Click to expand...

Right. And when you get it all welded up, the dimensions will likely end up different from when you started. TIG welding vs torch welding yield different lengths. I simply tried to keep centers where they belonged, the tail straight, and the stabilizer in the right orientation, as Mike noted.

Thanks for the offers of help, I might very well contact one or both you once I move further along. I'm content where I am with joining the members as of now and started cutting tube again this evening.

Funny you mentioned the difference of welding processes, I was talking about that with one of my buddies here today. seems like you'd get more shrinkage compared to tig with the larger heat zone. If I get bored one day I might do some comparisons and see if I can measure the difference in processes, only issue is I have next to 0 experience gas welding, guess I'll have to ask the girlfriend to do the gas weld she's good at it.

Ding! Ding! Ding! ATTENTION!

labrador_cub said:

....I"m starting to think someone just sat back and drew what looked like a fuselage and went back after and wrote in the dimensions. messing around with a dial caliper and doing some math every measurement I physically take on the plans ends up with a different ratio compared to the written dimension......

Click to expand...

One of the first rules of making anything from a blue print or drawing is to NEVER SCALE THE PART FROM THE DRAWING.
The only exception would be when there is a NOTE on the drawing to do so.
This applies to everything not just airplanes.

You all should be aware by now that Wag-Aero has never been precise nor accurate with their materials. Not just drawings. One of our fellow foreign members just learned this when he had an instrument overhauled. Nuff said.