parrthd

great to see the fuse coming together......

i feel your pain on the front fuse bottom formers..........i'll also "ditto" that about a razor plane being a neccessity......LOL

mmattockx

Looking great, Chris.

A trick I picked up from the composite homebuilding crowd is to use a balloon to pressurize the fuel system. Blow it up and hook it on to the fuel line, then measure the circumference of the balloon. If it gets smaller over night, you have a leak. Easy to do and measure with no guesswork.


Mark

Mods-R-Me

My Feedback: (1)

That's one heck of a razor planing job [sm=thumbs_up.gif]. I also like the copper tubing for the tank idea. Thanks for the tip!

Mods

ChrisMH

Cabines

1-3. Cabine holders have been epoxied in place after carefully establishing 1 degree of negative incidence. I used small strips of 6oz glass cloth and epoxy to reinforce the joints on the firewall and F-2 as there wasn't much glue area. Also, the bottom of the supports didn't touch the cockpit floor, so I used two pieces of light ply & epoxy to attach the cabine holders aft of F-2 to the cockpit floor. After that dried, the aft ends of the cabine supports were sanded and the instrument panel was glued in place.

4. After establishing the fuselage level laterally, using the wing saddle, I temporarily installed the fin and used a laser level to roughly position the tops of the the cabines in line with the fin. All of the front cabine wires were then wire-wrapped and soldered together using a propane torch.

5-6. I didn't particularly like that the directions have you align the cabines by eye and tweak them later when the wings are built. So I built a jig to help with alignment. The jig basically mimics the wing attachment, using two pieces of brass tubing and a straight piece of poplar that is exactly square to the centerline of the jig and extends equally on either side. The jig allows me to measure from the tail to the tip of each end of the jig just as if I was squaring the wing. Additionally, since the jig mimics the wing attachment, I can ensure that the tops of the cabines are collinear (i.e., the wing will slide on and off easily. After alignment, the rear cabine wires were soldered together.

7. Checking the alignment after soldering. The laser hits the tops of both cabine wires and the fin. You can't really see that from this picture, but it looks cool so I included it anyway

Forward Fuselage Sheeting

8-9. The forward fuselage stringers were installed and the center piece of sheeting was installed. I jointed both sides of the center sheeting before installing it. I'll joint the side pieces before they are installed for a nice tight joint.

10. I did not like that the sheeting near the cabines was unsupported, so I some used some scrap balsa to fabricate pieces that will support it. I'll sand these to the correct arc before installing the side pieces of sheeting.

TBC...

ChrisMH

Forward Fuselage Sheeting

1. To install the left and right sides of the forward fuse sheeting, first, after carefully fitting the sheeting around the cabines and instrument panel, I glued the sheeting to the already installed center sheeting and its stringer and allowed that to dry (I generally use Titebond, especially for sheeting, so it has to set up for a bit). Then I wet the sheeting and taped it to the fuselage until it dried.

2. After drying, I trimmed the sheeting to fit the fuselage sides and glued it in place.

3-4. Repeated for the right side.

5. Sheeting done.

Everyone have a happy non-denominational day off of work!

TBC...

parrthd

still looking good. this is the only place in the entire build that gave me fits. even after wetting the sheeting and letting it soak for 10 minutes, the sheeting still cracked in places. it wasn't bad and it wasn't anything that required the sheeting to be removed, it was just enough to pi$$ you off.......LOL

ChrisMH

Elevator & Rudder Controls

Before I button up the aft fuselage, I want to install elevator pushrod supports and make sure that there are no clearance issues with the pull-pull cables. So...

1. Control horns installed on the rudder. For a good pull-pull setup, it's important that the point where the cables attach to the control horns is either directly on the hinge line or slightly behind it. This ensures that the non-pulling cable does not become tighter than the pulling cable. I drilled mine so that they're about 1/32" behind the hing line.

2-4. Cables roughed in. I'm using plastic coated 60lb test fishing leader. Don't worry, I plan to use something other than masking tape to secure the cables to the rigging couplers

5-7. Testing the rudder. Looks like all the measuring I did paid off! No binding, everything looks OK.

8. Elevator pushrod supports glued in. The smaller tube is for the antenna.

Aft Fuselage

9. Turtle deck stringers installed.

TBC...

rideon67

My Feedback: (1)

Nice thread -- looking good. Re: the pull-pull cable. I used a sheath on both from where they entered the fuse to a couple inches from the servo arm and supported the sheath with balsa cross braces in a couple of places. This was on a big gasser bipe and those cables (steel on mine) shook like the devil beating into each other and causing all kinds of radio problems. Jeez, I hate vibration almost as much as gravity.

ChrisMH

Yeah, I didn't see any point to extending the sheath on the cables any further. They're basically just to trim out the exit hole in the fuselage.

Thanks for the compliment,
Chris

ChrisMH

Koverall!

Well, after some recommendations earlier in the thread about using Koverall, I ordered the necessary supplies. I've had it sitting around for a bit now and thought I'd give it a go. The only pieces I've to the covering stage are the elevators. As an added bonus, I hate covering control surfaces, so this'll be two out of the way

Any Koverall experts please feel free and welcome to chime in with tips, etc. This is my first time using the stuff.

Before starting, I gave both elevators a coat of nitrate dope thinned 50/50 with dope thinner. Then I applied stix-it to the edges.

1-2. I have never used this stuff before, so had no idea how it would behave when being pulled around curves. Since I wanted to ensure full coverage, I applied a strip of Koverall to the outer edges of the elevators and the inboard portion of the balance tabs. More stix-it on top of that.

3-4. The previous step turns out to be completely unnecessary. The Koverall pulls beautifully around curves. These two shots are closeups of the most curved parts of the elevators. This is without any shrinking; just pulling and tugging any wrinkles out.

After covering one side, I applied more stix-it to the areas where the second side would overlap and covered the second side. Edges are trimmed with a razor blade; there is some fraying but I've read that that will sand out after a couple of coats of dope.

5. Covered.

6. 1 coat of dope applied to everything and a second applied to the seams.


Couple of questions:

1. When, if ever, should I switch to full-strength dope?

2. How many coats do I need before painting? I'm not interested in filling the weave.

3. How many brain cells am I killing per coat? This stuff is stinky! Actually, I built some stick and tissue models as a kid, so the smell of the dope kinda brings back memories

TBC...

mmattockx

Nice work, Chris. Keep it going...

1) If you are using Stix It, than you never need unthinned dope. There is another way of sticking the Koverall on and this involves putting 2-3 coats of unthinned nitrate dope on the airframe, sanding between each coat. Then you lay your Koverall over the airframe and brush thinner (you can also use 50/50 dope) onto the Koverall where you want it to stick. The thinner soaks through the Koverall and softens the dope on the wood and the Koverall sticks as it dries. This works well and is an alternate if you can't use heat for whatever reason.

2) You will need a minimum of 2 coats, probably 3 of 50/50 nitrate to seal the Koverall. There can be no pinholes showing in the weave before you paint, or they will come through the paint as well. Ask me how I know... Just hold the pieces up to a light and look through the fabric to see if you have it sealed, the pinholes are very obvious. If you have an area that is giving you trouble sealing you can mix some talcum powder with dope to form a thicker slurry that will close up the stubborn holes. No primer is required if you don't want to use it, nitrate is an excellent primer for most paints. The only issue you may have is getting enough blockage from your base color without an opaque primer. And that just means an extra coat or two of color at worst.

3) My understanding (as an engineer, not a medical doctor) is that dope is not good for you (lots of volatile organics), but not nearly as bad as epoxies (lots of iso-cyanates). The difference is that your body can metabolize the VO's over time, but not iso-cyanates. So, if you keep your exposure levels low (that is, don't work with it for 8 hours a day, every day) then you will not cause serious harm over time like epoxies can. If you are worried, charcoal filter cartridge painting masks run only $20-$30 and they will eliminate a lot bad stuff. When you get to spraying, they become mandatory in my view, to eliminate airborne particulates and the vapors. As with any painting, keep the ventilation up and do not lock yourself in a small room with it for prolonged periods of time.


Mark

ChrisMH

Thanks Mark, good info.

Chris

ChrisMH

Turtledeck Sheeting

1-2. Side sheeting applied. I'm taking care to keep the tail aligned while gluing the sheeting on.

3. Top sheeting installed.

Two Steps Back...

After sheeting the turtledeck and rough shaping, some areas of sheeting were becoming so thin that it was nearly a sure thing I'd stick my finger through it at some point. Also, the sheeting was a bit "wavy", I think due to some overly aggressive taping on my part.

So, I ripped off the original sheeting & stringers and redid it with 3/32" sheeting.

4-5. The result. I'm much happier with this. You can't really tell from the photos, but it's well aligned with no "waviness."

Aft Belly Sheeting

6. I'm using a Sullivan Tailwheel bracket. This shot shows the mounting plate I made for it. 1/8" plywood with 4-40 blind nuts. The plate is attached with epoxy and glass cloth on the inside of the fuselage.

7-8. Left and right sheeting installed...

9. ...and rough shaped.


TBC...

ChrisMH

Fin Installation

1. I'm again using my laser level to mark out for the fin cutout in the top turtledeck sheeting. By aligning the cabines and the fin, I can ensure that the cutout points the fin straight down the centerline of the fuselage.

2. The fin cutout has been made and the turtledeck has been shaped.

3-4. The fin has been epoxied in place. After levelling the fuselage, I'm using my laser level to ensure that the fin is as perfectly aligned as I can make it.

TBC...

ChrisMH

Tailwheel

Since I'm using a Sullivan tailwheel, and since the bottom of the Skybolt's fuselage is narrow and curved at the tail, I need to make a flat mounting surface for the tailwheel.

1. I've sandwiched a piece of 1/32" plywood between the tailwheel and the fuselage. This piece of ply will be cut to the same size as the tailwheel bracket.

2. The 1/32" plywood cut to size and tacked into place.

3. Epoxy and (mostly) microballoons is used to fair in the mounting plate. After letting the epoxy set up a bit, I used my finger dipped in alcohol to smooth it out a bit.

4-5. Sanded and feathered out. I also mounted the rudder and sanded it at the same time so the fuselage and rudder flow together.

6. Completed.

Note: In these pics you might notice that the fuselage sides appear to change from one piece of wood to another about 2" from the tailpost. When I installed the fin, I mistakenly sanded a bit too much from the inside of the ends of the fuselage (i.e., where the fin TE glues into the fuselage. This makes the fuselage at the tailpost narrower than the rest of the fin. To fix this, I glued a piece of 1/32" balsa to each side of the tail of the fuselage and feathered it in. It won't be noticeable and fixes the problem nicely.


TBC...

rc-sport

My Feedback: (12)

Chris, nice work. At this pace what are your plans for the rest of the winter?

ChrisMH

Heh, yeah. I won't be able to start finishing this one until the Spring (need to be able to open the windows & doors!), so after covering I'll have to stop.

I'm thinking of scratching an Ultra Sport 60.

But something else may come up before that, so who knows

Chris

buzzingb

My Feedback: (2)

How much does the Skybolt weigh when finished? Sure looks like a lot of wood and materials in fuse.

ChrisMH

8.5-10 lbs. Varies, of course, depending on equipment. I believe those who've installed smoke systems have ended up a bit above 10lbs.

Chris

ChrisMH

Horizontal Stabilizer

1. Stabilizer base epoxied in. Before gluing, I jigged the plane level and -1deg incidence at the upper cabines. Then I installed the stab and checked the level and incidence. Level was spot-on, incidence required a smidge of shimming at the tail to achieve the +1.5deg stab incidence.

2. This closeup shows the small modification to the tailpost necessary since I'm using a torque rod to connect the elevator halves.

3. Stabilizer epoxied into place. I rechecked the incidence (spot-on), and squared it with the fuse using the rear cabine wire. Where would I be without my laser level? I wonder how accurate it actually is. Hmmm...

4. Stabilizer hold downs epoxied in. Now the whole mess needs to setup overnight and I can start closing up that huge gap 'twixt the fin and stab.

5. Rudder covered and first coat of dope applied. I think I'm hooked on Koverall. Or maybe it's just the dope high I'm cruisin' on...


TBC...of course...

MinnFlyer

My Feedback: (4)

Damn, I gotta get me one o' them lasers

ChrisMH

Yeah, if for no other reason than the nifty pictures

bldrums

Hey ChrisMH

First off , thanks for sharing some very helpful tips.
I wonder why you would install the rudder and elevator before you cover the hinged surfaces. Wont it be harder to get the covering to fully cover the joined (hinged ) areas. ?


Thanks,
bldrums

ChrisMH

I haven't permanently installed them yet. I have the hinges in place in some of the pictures, but nothing is glued yet. I'll fully cover and paint the model before gluing in the hinges. If you look at some of the later pics, you'll see the elevators and rudder detached and in the process of being covered.

My comment about them being a pain to install referred to drilling and countersinking the holes and cutting out clearances for the hinges to operate smoothly and with minimal gap.

Glad you're enjoying the build,
Chris

bldrums

Chris,
Great, thanks mon

gear up
Bill