N79FT A Skybolt Story

Messing with Cheetah, Footstep and Friends


On: Aug 18, 2014
In: blog
Tags: 9891U, flying, mechanicing

Weekends are plane days now. I fly to my friend's hangar and mess with 91U, the Cheetah (I still need a name for her :) ).

This past few weeks Ive been doing little stuff here and there...

Cleaned up the nav lights lenses.

Before

Before

After

After

... they still look like crap, so I'll probably bite the bullet and buy a set of new ones.

Oh, and I need to make those vertical "shields" that cover the strobes away from the pilot's view.. Ill probably get the new lenses after I make those shields.

Started getting under the panel and cleaning things up, preparing for the CGR-30 Engine Monitor installation (I got one for a really good price at Oshkosh).

Taking the glareshield off, found this:

All dead defroster SCAT tubing

All dead defroster SCAT tubing

I'll need to replace all that...

Started taking the old gages off and thinking about where Im gonna put what.

I'll need to make some plugs for the holes emptied.

Right now, I have analog and half-broken EGT (the selector switch is dead), analog CHT that's not hooked up to anything (wires are butted, and there are no probes installed). Those are going away. HOBBS is also going away. This is all being replaced with CGR-30, so I get a few empty holes and options to move gauges around. I'll probably move the clock and the vac suction gauge so that they're better visible.

Pictures will come later when the work is actually done :)

This last weekend started quite jolly with me putting in the engine grounding straps (didn't have them when I bought the plane).

Grounding Strap 1

Grounding Strap 1

Grounding Strap 2

Grounding Strap 2

And then, I decided to deal with something special; the Foot Step. You see, I don't like them. I think they're ugly. So, I decided to remove them, and make a couple of fairings to cover the holes up and to replace the original plastic fairings.

Beej helped me (that means, "did it himself" rather ;) ) whip out the first test fairing.

And then, we needed to take off the steps.

The steps are bolted thru the fuse honeycomb with a couple of backing plates. There are two bolts, top is aluminum one (the thought is that it will shear before the bottom one and therefore prevent leverage and damage to sensitive fuse sidewall honeycomb). I believe AG-5s (later Grummans) replaced them with steel bolts; and people had some serious honeycomb crushing issues because of that.

Aaanyway. The bolts come from the inboard side, thru the streamlined tubing of the footstep and a couple bushings, and fasten themselves to the nutplates riveted to the other side of the footstep. Here's the schematic from the Parts Manual.

Footstep Schematic

Footstep Schematic

There are a couple more bushings inside the streamlined tubing that aren't shown...

Also, the footstep sits in the wing root. You can kinda get access to the bottom nutplate if you take the fairing off. The top is right in the center of the wing root. And wing roots on Grummans are not fairings. I don't know how to remove one without pulling the whole wing (and Im not quite ready to do that yet...).

So anyway, happy me, I undo the rear seats and the cover that covers all the business under them, take the wrench, "assume the position" and start undoing the bolts. The first thing that happens is the rivets holding nutplates snap off.

So now, I am having Beej, not a small guy at all, under the plane on a creeper, holding the nutplates. We did the bottom one fast, the top one is a pain in the ass because it's, like I said, in the wing root. Had to take the flaps torque tube inspection plate off to get to it, and even then only could hold it with fingers.. the torque tube is getting in the way, you can't get any tools in there.

I should also mention that the bolts sit right under the back seat framing that holds the seat, and I can't even see the bolts I'm undoing without an inspection mirror. Gladly, not much there, so I've found them easily.

So, we undid the bolts.

Hehe. Now, to getting them out...

We were able to tap the bottom bolt out fairly easily. Well, it's right there under the footstep fairing, so that wasn't a problem.

The top bolt is the whole other story...

You see, the bushing inside the streamlined tube is steel. And the bolt is aluminum. The Mother Nature decided to give me a practical lesson on dissimilar metal corrosion.

So Saturday, as this was progressing and it was getting late (and time for Beej to go home), we tried pulling it, rotating it with a ratchet while pushing on the side. No joy.

Beej had to go. We had to disband.

I parked the plane in transient on Beej's field (I couldn't fly back with the footstep dangling like that on one bolt:)); and went home, determined to fix it. Had to have Dash pick me up...

Talked with Ben for over an hour.. Got a lot of good advice. "Heat it up". "Liquid Wrench". "Die Grinder".

Furnished a whole bunch of various tools. Some of them will probably scare some aircraft mechanics :)

The Tools To Pull That Bolt

The Tools To Pull That Bolt

Note the pry-bar notch enlarged to take an AN5 bolt. I also custom-beveled the cold chisel to give it a sharper angle (hoping I'll be able to get it under the bolt head).

Sunday.

Put a bunch of Liquid Wrench on that bolt. Tried the chisel - nothing.

Did I mention that I couldn't see the bolt, only feel it? :)

Tried pulling, rotating with Vise Grips - nothing.

Soaked in more Liquid Wrench. Nothing.

Looking at it from the inspection mirror, it was clear that I could cut the head off if I could see it (I would never try that blind. Ever).

So, the mission became the "See The Bolt Head" one.

Bottom interior side panel, if came off, would reveal the bolt from the top and give me access.

Top interior side panel was blocking the bottom interior side panel.

Also, seatbelts and a little latch for the rear seat.

So, off went all of that.

Finally, I saw the sucker!

Tried pulling it out a bit more, now when I had a better access point.. no luck.

Oh well. To The Dremel!

The rest is...

History :)

Holes after the bolts were out

Holes after the bolts were out

Patched with aluminum tape

Patched with aluminum tape

The footstand, with headless bolt shank and the bushing

The footstand, with headless bolt shank and the bushing

The nasty, nasty bolt shank with the bushing

The nasty, nasty bolt shank with the bushing "welded" onto it by corrosion

But the Mother Nature wasn't done with me yet.

Buttoned the plane back up; pulled it in front of the hangar, and took Beej to lunch.

Came back.

Realized that I left the keys to my car in my wife's car parked at a terminal.

Had to walk there and back. A good mile.

Oh, did I mention the 100 degree Texas summer? :)

Coming back, needed to push the plane back. But no - the parking brake on one of the wheels was completely and utterly stuck.

My Cheetah is a 77, and uses mechanical parking brake. Ive heard before that they get stuck; but I always was able to get them unstuck by taking the brake off and tapping on the pedals with my feet.

The way they work is there is a metal plate that has a hole thru which the brake cylinder's piston's shaft goes thru. There's a chain that pulls it up, making it eccentric with the shaft, which locks the shaft in place.

Well; apparently it got a little more hot while we ate, and that plate just didn't want to go down. Tapping the pedals while putting the brakes on and off didn't do anything.

Oh, did I mention that I would have fiddle with it, get out, try to push the plane back, fail, get back in, all in a 100 degree weather? Not fun.

Finally, gave up and "assumed the position" again. That's when you dive backwards under the panel with feet hanging out of the airplane.

Wiggling it for a minute or so finally yielded a loud snap, and it was unstuck.

Phew.

Flight back home was uneventful :).

Bonus pictures:

In flight, looking back over Downtown Austin (I risked my phone taking that!)

In flight, looking back over Downtown Austin (I risked my phone taking that!)

Skybolt:

Skybolt: "Are you talking to me!?" Cheetah: "No, are you talking to me?!!!"


Up ↑

Wings and Control System


On: Aug 12, 2014
In: wings
Tags: CAD, lower wings, ailerons, control system, fittings, fuselage

Ahh.. Finally. One week for a business trip, nothing done. One week and three days for Oshkosh. Nothing done (or rather, other stuff done :) ). And many more hours of fighting Solid Works; I finally have something to log! :)

Incidence and Fittings: Finishing Up

First, the incidence. Last time, I was trying to figure out how to deal with vertical fittings having to align with spars angled at 1.5 degrees up (incidence). A good discussion on the Forum ensued, and I figured (aside from me having to buy a +/- .0001 Precision Axe), to drill the hole at 1.5 degree angle in the front fitting, and forget about the little gap that shows up there, and weld the rear fitting in place. So something like this (you're looking at the fitting pair from the side, the CL is the hole centerline).

A pair of fittings, with the hole drilled at an angle

A pair of fittings, with the hole drilled at an angle

Gap that shows up when fittings are vertical, and hole is at an angle.

Gap that shows up when fittings are vertical, and hole is at an angle.

Note to self: When building / finish welding, I might reconsider and bend the tops of that fitting 1.5 degrees back to make everything flush. I probably will.

Back to the Control System

Next item on the list was bellcrank-to-aileron pushrod, which is tricky. See, if it's straight, it doesn't clear all the hardware.

Pushrod is not clearing hardware if straight

Pushrod is not clearing hardware if straight

So it had to be slightly bent to make the bellcrank side rod-end a bit more "horizontal", if you will, while not "horizontal" enough to hit the spar above.

This sounds easy; and probably is -- but tweaking splines, checking, re-checking and tweaking again while checking for full range of aileron's motion took up most of the time here.. I think I spent a good 10 hours or so just tweaking that one pushrod... And finally, here it is -- notice a slight bend in it. Just a touch less bend and it hits the washer under the bellcrank side rod end, just a touch more, and it gets dangerously close to the spar.

Aileron pushrod, tweaked to fit

Aileron pushrod, tweaked to fit

Finally, I was able to move the aileron linkage on the wing model and check the idler - bellcrank pushrod for ribs' verticals clearance. It clears! There's another clearance issue though - by the looks of it, it won't clear the compression struts (3/4 x 3/4 inch struts go in the middle of the ribs, forming wing bays along with drag/anti-drag wires) by the looks of it. So struts and wires it is, next, amongst other things..

Control system looking from the wing butt: won't clear the compression struts

Control system looking from the wing butt: won't clear the compression struts

Fitting Wings To the Fuse

For some reason, Solid Works gods decided to start hating me here. Remember the note about angled hole in the front wing fittings pair? Assuming that pair is mated to the fuse (lower longeron); front spar butt hole (ha.. ha ha.. haha..) mated to that angled hole in the fittings' pair should produce correct incidence; and dihedral can be set with wing spar centerline mated to, say, one of the fuselage's crossmember's centerlines, at required 1 degree angle? Ha! Yes; that worked -- but for some reason, would cause all kinds of shenanigans the moment I would make the SWX assembly flexible (== allowing me to move control surfaces of the wing sub-assembly as a part of the overall assembly).

Yeah-right. -3 hours of my life until I gave up.

Instead, I made a virtual "jig" -- another sub-assembly containing planes at correct dihedral and incidence angles. Wing's "Top" plane would mate to the "wing" plane of the "jig"; latter ("wing" plane) would be at 1.5 degree incidence / 1 degree dihedral. That worked.

The virtual

The virtual "jig" made of planes.

Dihedral of  the lower right wing

Dihedral of the lower right wing

That same "jig" assembly contains fittings mated to the wing spar -- and then, that "jig" subassembly is mated to the fuse via fittings - to - longerons mates.

That, for whatever reason, worked. After that, 10 more minutes of making one final pushrod connecting idler to Actuator Arm on the Torque Tube, and..

Control system all hooked up and working!

Control system all hooked up and working!

Happy me, making virtual airplane noises moving virtual torque tube moving virtual control system actuating virtual ailerons... Who says CAD isn't fun? :)

Now, back to those compression struts, only to find out that the pushrod does NOT clear... Le sigh.


Up ↑

Rant 1: On Building


On: Jul 14, 2014
In: blog
Tags: rant

I decided not to post current progress on the aileron linkage.. Too much work into it, and too little to show. It was mostly cleanups, and modeling a few missing pushrods. Still need to put more things up until there's anything to talk about.

So instead, I present you...

The Rant

Originally posted as a reply to a hundred (or so) year old question of "why" in yet-another-thread-on-the-topic on the Forum.

Me and Ben; both Grumman fans and AA5-B aficionados, are sitting in a $100 burger place called Props at Ben's home field, chatting hangar talk. A really slick taildragger pulls up to the pump. "Oh; that's an RV-8. It's a homebuilt" - says Ben.

One of RV-8s based in Watsonville

One of RV-8s based in Watsonville

I've heard about that some crazyfolk build planes in their garages before, but, being a fresh-off-the-rolls pilot with ~3 months of ticket behind me, never given it thought. My very first instructor's primary words were 'follow the procedure, checklist, certification, standards' (sidenote: I am not against following procedures, Im against instruction-without-explanation-of-why). Glad I ditched that guy 1/2 into my training... But you get the gist.

So, back to RVs. What a beautiful machine! Looks almost like a Grumman.. but slicker, newer, cleaner... And it's easy to build! And .. and ... and.

That times, I didn't have much background building stuff. I built some simple furniture with hand tools (think circular saw and trim router). I did some stuff in my mom's house back in Russia, primarily designing and building electrics and plumbing, when I was a teenager. I built office networks (15 1-inch holes in 3ft thick brick walls, anyone? Russian buildings are BIIG). I never really truly fabricated anything... Building computers was another one, but that one didn't involve any fabrication either, just making sure you put a cable right side in (anyone remember AT-style motherboard power connectors? "Black-To-Black", I will never forget ).

My experience level...

My experience level...

But I was always into tinkering with stuff.

So anyway, the whole idea of building a plane didn't scare me, and I was excited, but I wanted something with lots'a support, good kit, and such - because the idea of fabricating stuff scared me, at least somewhat. I also wanted something fast. The plan was, we move out of state (I was in CA back then, and that's the whole other story), I sell my share in my Tiger, add money, and build an RV. I really wanted an 8; but ended up deciding on a 10, because I like having more than one victim in my plane every now and then.

My dream plane.. back then.

My dream plane.. back then.

I just wanted a Grumman Tiger, Improved; costs wouldn't allow me to get and some other things repulsed me from Cirrus, Columbia, and a-likes.

I was on Van's forums, reading technical details, articles, and such.

I was studying intricacies of how to connect Dynons with a 430 and make it a certifiable IFR EFIS with GPS. I was almost about to start my IFR ticket training, BTW.

I was dead set.

And then, that same Ben got me a ride in a Stearman with his buddy Jerry. That guy never ever flew a nosewheel, BTW; that day I caught Ben convincing Jerry that he has to get in Ben's Tiger and learn nosewheel finally ("yeah.. it's the same as a Stearman.. just never wheel it!" - Ben was sagely saying to Jerry at Props), and then Ben went "Oh Fidot, that's great you're here - we gotta put you in a Stearman". And they did.

That Stearman

That Stearman

That day, in that first loop on the top side, my world was upside down, quite literally. I did IFR before; Drew, my second instructor, was a professional torturer (and great one at it; Im yet to see an instructor that comes even close to Drew). He made me do DME arks and shoot ILS approaches as a part of my VFR training, Because He Could (and we got that nasty marine layer in Oakland every now and then). I never did acro; not even spins though.

But That Loop... that was something completely out of a different world. The difference between never flying an airplane and flying a ratty Cessna 172 for the first time during the misleadingly cheap "demo flight" was probably less than the difference between having ~150 hours in nosepushers as a 'Private Pilot, ASEL', and doing a loop in a Stearman.

That caused a lot of thinking; a bunch of reading; and a ton of soul-searching.

As a result, my IFR money went into basic acro training (that I couldn't finish because I ended up moving out of state, after all, and there's no good acro schools around where I am right now).

As a result, RV-10 that flies dozens of pounds of electronics was ditched for a biplane. And open cockpit. And a 2 seater ('cause I like victims!!).

And most importantly, came a realization. You have to build an airplane to experience building an airplane. You can't build one 'cause you want one cheap, or you just Want One. Man, you can pick up an oldish Cub or a Citabria for about 30 grand; and a Yankee for about 25. Hell, you can pick up the homebuilt you want for less money than it's gonna cost you to build, if you're patient enough (and even if you have to wait for a year for one to pop up, you will still spend less time than putting together a kit (2-weeks-to-taxi et al excluded)).

Yeah.. Ill build THAT instead.

Yeah.. Ill build THAT instead.

And 'cause I wanted to build to Build, I had to do it the right way. So, plans-built it was. I got the plans about a year and a half ago, and went thru mood swings between 'damm this is awesome' and 'damm Ill not fly for 10 years or will have to buy components or cut corners'.

There was, and is, a problem, and a hard one for me. Im addicted to flying. I did ~190 hours in the Tiger over a year and a half I owned that share in before moving out of state.

That Tiger; BTW...

That Tiger; BTW...

But Im also addicted to building.

So I ended up deciding for myself that Im gonna do both. And I am. And I couldn't be happier. I don't need That Plane Im Building right now, I have something to fly. I decided not to rush, and just Take My Time; just make sure to not take multi-month breaks. 10 years, whatever. Im not in a rush.

Plus, my thinking is that works our real well with $$. You don't have to give tens of Ks of Presidents' Portraits to Vans or anyone else all at once. You pay as you go, and you build as you go. Got a bonus? Put it aside for an engine. Don't have one? Get some tubing and burn some holes in metal. Hey, I bet you can get cutoffs for dirt cheap or free at you local metal yard or whatever. Don't have any money? Do some reading, drawing, learning, and such. Hell, learn mechanical engineering. Aerodynamics. Structural analysis. 3D CAD (that's my current gig ). Hang out and help other folk in your chapter build things.

President's Portraits

President's Portraits

Bottom line, Build to Build, and To Learn, not to Fly, or to Have an Airplane For Cheap.

Fi.


Up ↑

An Unintended Trip


On: Jul 07, 2014
In: blog
Tags: 9891U, flying

Heh. Multi-week moments of silence seem to start taking hold here. I haven't got much time to work on anything lately.

You see, I have finally decided that I am going to get myself something to fly while I work on the Bolt. I haven't flown for some months, and the withdrawal was settling in pretty badly.

Problem is, I moved to Texas about 8 months ago. Back where I lived before I used to own a 1/3 of a Grumman "N28797" Tiger; flying her at least once a week. I often would spend weekends bouncing between airports and hangar-flying in between hops, and took her to Oshkosh last year.

After moving, the only airplanes I was able to access were ratty Cherokees and Cessnas in a local flight school; and I could no longer go on my day-long hops just because it was too expensive. Writing $400 checks every time I went flying just... hurt, and I ended up not flying much.

So, a decision was made. I was to buy a plane.

A few strategically placed calls to my friends back in California immediately yielded a very good deal on a Grumman Cheetah (it had to be a Grumman of course) :).

Now, Cheetah is the same airframe as Tiger less 200 pounds of max gross and an O-320 instead of an O-360. Figuring that I now live on the right side of the Rockies and don't need to cross them much, my thinking is that Cheetah will actually suite my mission much better.

So, I hopped on a Winged Tubular Human Transporter, and was in CA a few hours later.

A mandatory airport shot. KAUS tower.

A mandatory airport shot. KAUS tower.

I was out of BFR; so we had to get that squared away first... No problem - AYA's Ben Rolfe, my good friend and Grumman mentor and fellow aficionado, told me that AYA was having a fly-in in Delano, and we went for it.

Oh man, I haven't flown a Grumman for a year! What a feeling it was to fly the airplane you truly know and love to fly, again.

Ben sharing bits of wisdom at Delano airport's restaurant

Ben sharing bits of wisdom at Delano airport's restaurant

Grummans (not quite a mile of them :) )

Grummans (not quite a mile of them :) )

Stu's Tiger

Stu's Tiger

The Bird of the Day: Ben's Tiger

The Bird of the Day: Ben's Tiger

..and finally, I meet the seller of my future plane at Abundant Air in Palo Alto. And the plane. 9891U!

Meet the Cheetah!

Meet the Cheetah!

LoPresti, Powerflow, and 160HP pistons STC. No wheelpants (will have to put those on, but okay for now). Basic panel. 400 hours on engine. Love it!

LeRoy loved her too. (LeRoy is my plush co-pilot. He likes Grumman Tigers the most, but liked this Cheetah a lot, especially 'cause of the colors. They got along real well!!!)

LeRoy getting acquainted

LeRoy getting acquainted

Over that week I was in CA after buying the plane, I have flew more than I have flew over 8 months in Texas.

I got checked out with Drew Kemp, my CFI and guru, gave some old friends a long-overdue ride over San Francisco, visited some more of the old friends in airports around CA, including the awesome Gary Vogt of AuCountry fame , and read lots of paperwork.

Funny thing: apparently one of the radios was stolen from this plane in 1995..

Stolen radio mentioned on this invoice

Stolen radio mentioned on this invoice

And finally, we were off to Texas!

Windmills in CA

Windmills in CA

LeRoy flying

LeRoy flying

Refueling in Apple Valley

Refueling in Apple Valley

CA-AZ border, Colorado River

CA-AZ border, Colorado River

Buckeye: approaching Phoenix. Lunch time!

Buckeye: approaching Phoenix. Lunch time!

After lunch in Phoenix, we took off... My second in command Dash noticed high oil temps -- and I reduced the climb, leveling off finally at 5500. The oil just did not want to cool! Half way between Phoenix and Tuscon, the oil finally got a bit cooler, and I attempted climbing some more, but no joy. The moment I start climbing, the oil would hit redline. After trying that a couple times, we decided to bail in Tuscon, and spend a night there. Plan was to take off at 5:30 in the morning, and get past high terrain that starts after Tuscon early in the morning.

Cooling off in the FBO at Ryan Field near Tuscon, we started looking for options. It was Saturday, so renting a car didn't work out. I found a business card for Jeannie's Taxi in the FBO and called her up.

Jeannie's great! She came out immediately, and took us back over a great little road winding thru the Black Mountain and Old Tuscon; and agreed to pick us up at 4:30 in the morning!! We also had a great conversation pretty much about everything as we drove.

Next came Demming, New Mexico. A sad sight of an Arrow stuck on a runway at a weird angle warned that something was amiss. Luckily, Demming had two runways so I landed on another one. Noticed guys at the FBO already rolling in a golf cart to a now obviously belly-landed retractable Arrow, and decided to just wait.

The FBO guys rolled in a few minutes later. "What happened? Did he forget?" - "He forgot". Oh well. Gas-Undercarriage-Mixture-Prop...

One of the guys started fueling us. They have already lifted the Arrow, extended the landing gear, and rolled her into a spare hangar by the time we were leaving.

Fort Stockton was our last en-route stop; and three hours after that we were approaching San Marcos, my temporary home.

17 hours.

What a trip.

I am no longer planeless.

Amen.

Home

Home


Up ↑

Fitting Lower Wings To The Fuse


On: Jun 17, 2014
In: fuselage
Tags: CAD, fuselage, lower wings, fittings

Today, ended up messing around with putting the lower wing and the fuselage together...

Lower wings are set up at 1.5 degree incidence, 1.0 dihedral.

Started with that I realized that I mis-positioned the hole on the front spar and gear fitting. Simple fix :)

Next, came a lot of thinking and reading. Here's the problem.

The plans position fittings perpendicular to the longeron.

Fittings on the lower longeron

Fittings on the lower longeron

Holes are co-linear, and incidence is achieved because of the stagger in the attach holes on the spars. Airfoil chord, tilted up 1.5 degrees make these holes come together.

The problem is that spar sides then become non-coplanar with the fittings' faces; possibly introducing bad fit, play, misalignment, and whatever problems I can't think of.

Here's how the spars go 'into' the fittings. I circled the rear spar, since Ill use that for illustrating the problem.

Spars on fuse (rest of wing hidden from view not to obstruct

Spars on fuse (rest of wing hidden from view not to obstruct

Now, looking at it from the tip of the spar towards the fuselage, you can see the angle between the fitting and the spar. That's because of 1.5 degrees of incidence.

Angles don't match == no fit.

Angles don't match == no fit.

This problem caused about an hour and a half worth of research with no results...

Firebolt and Pitts plans explicitly state either bending, or welding fittings to longerons at correct angles. Not Skybolt though...

Ended up posting on the Forum. Let's see what the folks say....

On a more positive note; I can see an outline of an airplane in this now ;) Made some virtual, mental airplane noises :)

Airplane!!!!

Airplane!!!!


Up ↑

Lower Wing Fittings and Torque Tube


On: Jun 16, 2014
In: fuselage
Tags: CAD, fuselage, torque tube, control system, ailerons, elevator, lower wings, fittings

For starters, cleaned up the torque tube; added all the hardware (thanks cwilliamrose again for AN hardware models!) and proper mates. Was a nice warm-up, and came out real well.

Torque Tube, Cleaned Up with HW

Torque Tube, Cleaned Up with HW

After that, added the lower wing front fittings to the fuse. Piece of cake! :)

Lower wing front and gear rear fittings

Lower wing front and gear rear fittings

... and zoomed in.

... and zoomed in.

Notice on the above picture how they interfere with the tubes of the fuse truss (geometry penetrates one another). There are a couple ways to fix that; plans just call for 'trimming in place'. Note to self: figure out if the weld should only be around the bottom longeron; or if to weld the top of the fitting to the vertical too?

The cool thing about SW is that I can "cut" in place; add a bit of margin on the real pattern for the fitting, and make it to fit without constant trial and error.

And then, lower wing rear fitting.. that one is tricky due to the way it's dimensioned on the plans (it makes sense plan-wise, since it maintains clearances between longerons and spar butts, etc; so hole positioning takes metal thickness into the account). Can't believe it took me 2 hours and a few tries to figure out how to model this right. Learning curves be damned :)

Lower wing rear fitting

Lower wing rear fitting

Now, the reason for all that trouble is that getting the flat pattern out of that is just 1 mouse click!

Lower wing rear fitting

Lower wing rear fitting

I think this was a great day. :)


Up ↑

Torque Tube Basics


On: Jun 15, 2014
In: fuselage
Tags: CAD, fuselage, torque tube, control system, ailerons, elevator

Started modeling just the very basics of the torque tube. The idea is to hang it on the fuse, attach the aileron pushrods to it, and check clearances in the wings (and finally get to start making them! :)).

Just a few screenshots today. Lots of time spent reading plans (haven't paid as much attention to Fuselage / Control Stick setup as I did to the wings).

Gladly, I had the truss model from way back when (I did it to learn SolidWorks Weldments feature).

Anyways, pretty pictures below.

Aileron Actuator Arm Sketch

Aileron Actuator Arm Sketch

... and model.

... and model.

Torque Tube Collar

Torque Tube Collar

Very basic model of the Torque Tube (but all I need right now, minus the aileron arms)

Very basic model of the Torque Tube (but all I need right now, minus the aileron arms)

Torque Tube on the Fuselage

Torque Tube on the Fuselage

And eyeball alignment check - fits!!! :)

And eyeball alignment check - fits!!! :)


Up ↑

Pushrods, bearings, and clearance


On: Jun 09, 2014
In: wings
Tags: CAD, lower wings, control system, ailerons

In the past couple of evenings; have continued hanging virtual control system on the virtual wings.

Thanks to CWilliamRose from Biplane Forum, I now have quite a bit of models of AN / MILSPEC bearings.. REP3H5 included, but he didn't have REP4H6, so that had to be done first..

REP4H6 bearing model

REP4H6 bearing model

Couldn't find a few dimensions; but my rationale is as long as the basic eye height / bore / shank are there, and the ball 'rotates', that's good enough for the purpose of my alignment checking, for now at least. Ill revisit if I start getting into tight corners.

Next, hung the Idler, bearings, cleaned up the model (funny, lower wing assembly is technically my first serious SolidWorks model, so I keep cleaning it up as I go, killing stupid things I did back when I didn't know any better).

Sigh... I will need to hang the wing onto the fuselage model to make sure the pushrod doesn't hit verticals -- clearance is there, but might not be enough.

Here's the wing model with the pushrod:

Idler, bellcrank, and pushrod -- there is clearance, but is it enough?

Idler, bellcrank, and pushrod -- there is clearance, but is it enough?

Here, it's looking at the rod from the tip,  the rod is  that white thingie right of the rib verticals

Here, it's looking at the rod from the tip, the rod is that white thingie right of the rib verticals

So, I guess, to the wing fittings and control stick assembled with fuse models tomorrow.

And to finish today off, here's the full zoomed out picture of the lower wing, as it is right now.

The wing

The wing


Up ↑

The Shop Day


On: Jun 07, 2014
In: blog
Tags: tools, shop

So, originally it was supposed to be the shop day. I was gonna clean and put together the compressor I picked up off a gentleman on Craigslist, and set up the air hoses, filters and such - and then, back to CAD. And then..

See, I was looking for a bandsaw. I wasn't in a rush, so I was gonna pick up a good used one; so I was watching Craigslist and such, waiting and waiting. After doing that for about 6 months and after I got tired of not having one; I finally said "screw it" and bid on one on Ebay.

I won it on Friday around 4pm; paid, and went home. Well; there, in my Gmail's Inbox, was a notification from CraigWatcher saying that yet another bandsaw ad was posted... I opened it up; and couldn't believe my eyes.

Someone was selling.. an 18 inch Grizzly saw for 250 bucks! I couldn't pass on it; and next morning was driving back with a 300 pound beast in the back of my car....

... and then, spent a week and a half cleaning it up. I polished the rust out of the table; changed some bearings, re-cut threads on the blade tensioning rod, added a 4 inch dust port (for whatever weird reason, Grizzly decided not to put a dust port on this particular model).

It also ran on the 220, so I had to add a 220 outlet to the shop... Decided to go all out; and added a 6 gauge run with 50 amp breaker, so that I can run a TIG welder off of it when I get one.

So now; I own two bandsaws :).

Here's the perpetrator:

The Bandsaw

The Bandsaw

Since we're talking shop....

Right now Im set up in the garage of the old house we bought about half a year ago. Dash (my beautiful wife) is working on designing a new house we're gonna build; and that one is going to have a good sized shop. We will build that house first and then demo the old house; so I could start setting up earlier than I thought I would be able to; which is certainly nice.

But; Im dealing with 40 year old electrical; and other fun stuff..

Here are some pictures of that garage, ordered historically, as I was setting up.

Just after washing everything with a pressure washer...

Just after washing everything with a pressure washer...

The beginnings of the storage spot

The beginnings of the storage spot

.. all that empty space :)

.. all that empty space :)

That's pretty much all my tools before I moved (the big red chest is new)

That's pretty much all my tools before I moved (the big red chest is new)

First batch of stuff - table saw, jointer, planer, drill press. Excited!

First batch of stuff - table saw, jointer, planer, drill press. Excited!

.. and set up!

.. and set up!

Storage's getting a bit more crowded

Storage's getting a bit more crowded

Setting up lighting. All that wood is for the benches.

Setting up lighting. All that wood is for the benches.

First bench - the frame is ready.

First bench - the frame is ready.

The benches are up - and this place is starting to look like a shop!

The benches are up - and this place is starting to look like a shop!

.. yep

.. yep

Next, some 2x4s put together into a material rack. Cleared a lot of space!

Next, some 2x4s put together into a material rack. Cleared a lot of space!

Storage again

Storage again

Air setup, router table, and The Bandsaw

Air setup, router table, and The Bandsaw

Added some entertainment :) Also, the little Delta bandsaw on the bench

Added some entertainment :) Also, the little Delta bandsaw on the bench

I like how this looks!

I like how this looks!

And here are a couple pictures of the tools...

Air setup is very simple, a compressor with a shutoff directly into an air filter, regulator, and 25 feet of hose on a reel. That reaches pretty much everywhere.

The Air Setup (very simple for now)

The Air Setup (very simple for now)

At some point; I measured the runout on the drill press -- got around 10 thousandths - no wonder why it was all vibrating when drilling deep holes!

Grizzly includes very cheap chucks and arbors with their presses... Gladly, the bearings have no play though. I ended up picking up a used Jacobs chuck on Ebay, and boy, what a world of difference! Used a SouthBend arbor picked up on Amazon.

The Jacobs Chuck

The Jacobs Chuck

I wanted a router table; but didn't want to pay around a grand for the one I like (and cheap ones are just.. crap, honestly); so I built one.

Top is two sheets of 3/4 MDF, laminated together. White Formica is laminated on top, bottom, and sides. All done with DAP Weldwood contact cement.

I bought the insert plate (though in hindsight, I should've just bought a hunk of aluminum and made it myself).

It still ended up being a bit out-of-flat, so I built a leveling system into the base (two bolts on each side are pulling the top "down", screwing into holes in the top with threaded inserts; and there are two screws pushing up on the top in the center of each long frame side. All that allows me to work out any non-flatness out of the top.

Fence is 3/4 ply; and the router sits in the box under the table. The box has 4 inch dust fitting epoxied on it on the other side (and the fence dust collector feeds into that fitting too).

The Homebuilt Router Table.

The Homebuilt Router Table.


Up ↑

Bellcrank and Idler


On: May 22, 2014
In: wings
Tags: CAD, lower wings, control system, ailerons

It's almost 5 am and Im finally done with the bellcrank alignment! Phew.

By the way, sheet metal stuff in Solid Works is amazing! You give it the bend lines, radii, and a couple more parameters; and it automatically creates both the bent item; as well as the flat pattern. Print the pattern, glue, and start bending -- it will show you which line, how many degrees, and in which direction to bend. Ill post one of those final drawings later, when I get around to printing them and bending some actual metal :).

Anyway...

The night started quite jolly with me whipping out the idler arm with it's bracket. Looks pretty neat, eh?

Aileron Idler Arm and Bracket

Aileron Idler Arm and Bracket

And then, back to the bellcrank hell. I had it modeled back in the days, and the "jog" bend 1/2 inches down made. Here's how busy the sketch with all the radii and holes looks BTW; pre-bending.

Bellcrank layout

Bellcrank layout

Anyway, with all the sheet metal awesomeness SolidWorks doesn't know how to twist. You can twist a model by using deformation, but at that point all kinds of shenanigans begin to happen. For example, all faces of the model stop being planar faces (meaning nothing can be sketched on them, and sketch is how you start defining a feature (part of the model)); for some reason I wasn't able to put a reference point into the center of one of the holes, etc. (I ended up drawing that point finally by projecting that hole's centerline onto one of the faces; that did work for whatever the weird reason Solid Works gods must have).

Bellcrank, bent and twisted

Bellcrank, bent and twisted

And after fiddling with it for about an hour, I was finally able to position everything. The plans don't specify where the bracket should be, so my educated and logical (yes, mr. Spock?) guess was that it should be so that the aileron pushrod connecting bellcrank to the alieron hinge is aligned and straight in the "aileron neutral" position. So I used the aileron hinge center as the reference; squared the bellcrank and aligned it that way. Note the blue line (that's actually a plane bisecting the aileron hinge), and the Point1 (that's that wretched point on the twisted surface that took me so long to figure out). That's what I used for alignment.

Bellcrank mated and aligned with aileron hinge

Bellcrank mated and aligned with aileron hinge

Coming up, putting in the idler, all the pushrods, and checking clearances with rib truss throughout the full range of motion. I strongly suspect that I will need the control stick's model on the fuse to do that, since that's what the other end of that pushrod attaches to. Oh man... gotta love those dependencies. That just means that I will have to do that model earlier than planned. Oh well. I like Solid Works anyways...

Tomorrow's the Shop Day! Gotta clean and put that compressor together.

OK 5:11 AM; time to go get some sleep :)



Powered by B-Log, which is based on Pelican, heavily plugged and themed.

© Copyright 2014-2015 "N79FT". All rights reserved.

This construction log only shows how I did things during the construction of my Skybolt. These pages are for information and personal entertainment only and not to be construed as the only way, or even the perceived correct way of doing things. You are responsible for your own construction techniques.