That there folks is $213 of plywood and vertical grain Doug fir. I think I've blown my airplane budget for a few months. But i also think i can get a lot done on the outer wing panels with it so, yeehaww!
Made a taper jig to cut the outer spar caps. The spar caps are 2 inches x 2 inches tapering to 3/4 x 3/4 at the tip and are about 86" long.
Ripped a piece of the Doug fir down to 3 inches wide which will allow me to get 2 caps out of it and used some scraps to clamp it onto the jig. If it's not clear all the screws are into the jig not the spar material.
It's a little late so I'll do the cutting tomorrow after I've had a chance to double and triple check the setup.
Well I managed to get all 4 spar caps out of the board i bought.
If i were to make an analogy of the experience it would be like telling a drag racer he has a 2 lane road full of potholes to race on and has to do 2 passes and can't drive over the same asphalt twice or there'll be a hefty fine.
The potholes being knots/ imperfections in the wood and the fine being the cost of screwing up.
There's gotta be at least $30 worth of sawdust right there.
Christmas came a little early. That is a lot of weight in steel right there. The wing attach fittings will consume a lot of that big piece as well as the landing gear mounts, the 1" tubes are to react the landing gear loads between the front and rear spars and the smaller tubes are the compression bushings for the wing attach plates.
Spent a few evenings making a scarfing jig for my planer (from harbor freight). Scarfing with my table saw didn't work so good, biggest problem i think is that it's under powered, so looking for another solution. I googled"planer scarfing jig" and something called "the Henry" came up and i have been trying to duplicate it. Haven't quite got it cutting the correct angle yet but initial results are very encouraging. I think I'll be able to get a much better scarf than with the table saw.
I've had the plywood pieces rough cut for the outer spar shear webs for over 3 years but couldn't glue them together because i couldn't do the scarf cut. Now hopefully by tomorrow i can get the jig fine tuned and maybe even mix some epoxy.
Those spar caps are just begging to be made into spars (also don't want to give them a chance to twist and warp on me).
One of my new years resolutions was to work an average of 10 hrs a week on my plane. Of course life happened and i blew it the first few weeks. My el cheapo underpowered table saw decided to have more issues, this time the fence broke, not a great loss as it wasnt very good anyway. This prompted me to look for a better table saw and i think i found a pretty decent one even though it's a craftsman as well. This one was originally a $550 saw 10 years ago and has to weigh about 200 lbs, with a much more powerful motor and a very nice fence for only $200. Just had to order a new drive belt then i can get to cutting longerons.
In the mean time I've started building the mold for my canopy. Last Saturday i had all the templates printed out full size and tonight i finally got around to gluing them to some osb. It's slowly coming together. I'm sure this will be amusing to those of you who have experience building molds but gotta start somewhere.
Thought I'd add the sheetrock square just to give some sense of scale. The plan right now is to pour foam into the spaces then sand it to shape then apply a hard coat to it and sand and sand until it's mirror smooth. Havent decided if I'll pull a female mold off it when I'm finished.
Glued the rib templates to the plywood and started cutting them out. There's more time this evening but I'm tired, going to kick back a little. The ribs are doubled up, hence the screws. The outer panel is triple tapered with a Horner tip. The ribs will slide over the spars, then I'll put foam blocks in between and sand, just like the h-stab.
I designed it that way just to closely approximate the spitfires wing, without the headache of a true ellipse, but according to a thread i read recently that's an ideal way to get good elliptical lift distribution and maybe a few other aerodynamic benefits. It'll look good and hopefully fly good.
This came in the mail today along with the drive belt for my table saw, so I'm out of limbo!! Guess i wasn't really in limbo since there are other things i can do without the belt but it's what i need to really get cracking.
I'll watch the video a few times then start tearing down the 13b core I've got to see if it is worth rebuilding.
One other huge thing of note is the week before Christmas i discovered a guy in my EAA chapter has access to a CNC plasma cutter and he offered to cut out the wing attach fittings and other steel parts for me for free!!!! I realized that the design especially the main gear mounts needed a little tweaking so I'm just about ready to email the files off to him. He's even got a cnc bender and since some parts need to be bent he'll do that as well! Exciting stuff coming along.
I have to admit to feeling a little stupid right now. I can't remember who or when but someone suggested sanding down the plywood for the wing spars to make the scarf joints. I totally disregarded this advice at the time feeling I absolutely needed my table saw to accomplish this task. The ceiling in my basement is too low to do it that way and the scarfing jig i made for my planer wasn't doing as nice a job as i wanted, so i sanded the scarfs last night and just now finished epoxying the main outer spar shear webs together. Those pieces have been cut waiting to be scarfed for nearly 4 years now, and it was so easy once i got started and there's only the aft spar shear webs left to do, then all done scarfing forever on this project. It's not like I have to set up an assembly line. Like i said feeling a little dumb.
I thought about posting a pic of the top cap being epoxied for the other spar but it looks pretty much the same as yesterday's progress pic just backwards. Got 2 of the 4 shear webs for the aft spars scarfed and epoxied, still have to scarf 3 more pieces of plywood for the aft spars. Always less than I'd like but it's progress.
The upper spar caps (further from camera) on both main outboard spars are now epoxied in place, though not visible in this pic there is a slight curve to the upper cap. It was relatively painless to clamp it down. The bottom cap has a much more pronounced curve and takes a little more persuasion.
I'm not epoxying it tonight due to other priorities but thought leaving it clamped in position might make it take a bit of a set so it'll be easier when the time comes.
Also i think I'm going to install all the intercostals before i attach the lower cap. That way i have something to clamp against.
Purposely ditched the monthly chapter meeting last night so i could work on finishing up the design of the wing attach fittings and other associated parts which i loaded onto a thumb drive today and handed to the guy who will be cutting them out on his cnc plasma cutter. Probably take him a few weeks to get it all sorted out and ready for his machine but even at that rate they'll be ready before I'm ready to use them. Still not up to my new years resolution goal of 10+ hrs a week working on the plane but I'm working up to it.
Last night i epoxied the lower spar cap to the shear web of one main spar and finished scarfing and epoxying the shear webs for the aft spars.
Today I epoxied the lower cap to the other main spar, glued the template to the aft spar shear webs and cut them out. I also ripped down the spar caps for the aft spars and also managed to get the top cap epoxied on one of them.
With a diy arduino engine monitor which looks promising. I rearranged the display to meet the needs of a rotary installation and the above is what i came up with. I'll need my dad's help with it. He's a electrical engineer that designs and programs industrial machinery so this ought to be child's play for him.
Earlier today a member of the local eaa chapter took me flying in his RV9A and it was what i needed too get my motivation going again. He let me fly it from shortly after takeoff to just before entering the pattern. It was a lot of fun.
Above are the 2 main outer spars with top and bottom caps epoxied in place. Just need to add the intercostals and seal the wood then i can close them up by adding the shear web.
Those are the aft/ drag spars having the spar caps epoxied in place, on the right the lower cap is being joined (top already done) and on the left the top cap for the other spar is being glued in place.
Also did a little work on the upper longerons. Although I'm done scarfing plywood i have to lengthen the longerons a little, kind of a pain but it's the cheaper option. Good Doug fir is expensive.
nothing in terms of actual building got done this week for 2 reasons. Most embarrassing first is that my nice granite work table has a sag in it which was built into at least 3 of the outboard spars. Fortunately i don't think I'll have to remake them, just have a straight flat surface when i install the other shear web and i think they'll be okay, i hope anyway.
The second reason nothing got built was that i was working on the design of the torque tube for the flaps. At the minimum i want the pillow blocks that hold it mounted before I install the foam shell between the seatback and the bulkhead aft of it because it will be extraordinarily difficult to work on it at after that.