mmattockx

Chris,

Are the plans detailed enough to scratch from? Do they show formers and a decent number of cross sections? Are you willing to share copies of your parts tracings?


Thanks,
Mark

ChrisMH

The only thing misssing from the plans may be rib outlines and the special ribs for joining the wings and attaching the top wing to the fuselage. I don't think the outlines for all the wire pieces are on there, either. I'll have to check tonight when I get home. All of the fuselage formers and outlines are on there. I wouln't think it would be a big deal for an experiences scratch builder to build from the plans.

As far as sharing tracings I make, I'd be more than happy to as long as I'm not stepping into any legal issues with Great Planes...anyone have an idea of the "legalness" of sharing this information?

Chris

ChrisMH

Mark,

I took a look at the plans this evening. As far as I could tell, the plans contain all the info needed to scratch build a Skybolt.

Chris

ChrisMH

Didn't do much tonight. Finished up the stabilizer and elevators.

Robart hinge points are kind of a pain to install, but I really like how well they work.

TBC...

mmattockx

Thanks for the help, Chris. I may have to buy a set of plans and take a look for myself. Maybe this will be next winter's project, since this year is already booked...


Mark

ChrisMH

Fuselage construction.

1. F3-F5 installed while the fuse sides are jigged.

2-3. More detail on the jig. The fuse sides are clamped flush and square at the tail. The sides further forward are clamped square and registered on the same plane. I'll glue as much in while it's jigged like this to ensure I end up with a true fuselage.

4. Belly former and aft wing bolt plate installed. I'll be using epoxy from the bolt plates forward.

5. After letting that cook for a bit, the forward bolt plate and F2 are epoxied in. It's on its nose as I ran a small fillet of epoxy around the aft side of F2 to ensure it's well bonded. Everything is held in place with strapping tape and I'll let it cure overnight. Hopefully, it won't explode when I remove the tape! (The fuse sides are 1/4" thick and require considerable coercion to conform to the fuse formers.)



A question to anyone who has installed a pull-pull rudder, which I'm planning to do. Is it kosher to cross the cables in the fuselage? I'd like to do so so that the point that the cables enter the fuselage is further aft. I'll be using pushrod outer tubing to trim the exit points, and I was thinking that I'd extend them forward to the point where the cables cross so that they wouldn't rub on each other. I can't think of a reason why this would be a problem...



TBC...

krossk

My Feedback: (27)

I used a pull-pull on both the rudder and elevator in my Somethin' Extra and did cross the cables on the rudder with no ill affects. In my case, it allowd me to run the cables in a more straight path with less deflection upon exiting the fuse. The elevator setup rotates the plane of the cable path by 90 degrees from horizontal to vertical and it works great as well.

mmattockx

This is done all the time on pattern planes to get better/more convenient geometry. It will cause you no issues at all compared to un-crossed cables.


Mark

ChrisMH

Thanks for the answers. I'll be crossing the cables.

Chris

ChrisMH

Mounting the engine today, so I can prep the firewall for installation.

1. Nifty jig I made to ensure that the mounting holes are drilled nice and square. I'm using a Dubro isolation mount...or so I thought...

2-3. After drilling and tapping...aaaaah *#*&#(*(#. This engine mount's gonna interfere with the cabine supports mounting in the firewall. Harumph. After thinking a bit on how I could support the cabines some other way, I guess that the best solution is a different engine mount. So there's $35 down the toilet. Oh, well, guess I'll have to build a 120 size plane that this mount will fit

Anyone know of mount that'll fit this bird? The GP adjustable one just seems so cheap to me...

TBC...

lwf

Check out the cabanes on the Great Planes Ultimate.

MinnFlyer

My Feedback: (4)

Chris, the mount that comes with the Skybolt will work fine. I used mine with an OS 91 and later upgraded to a YS 110 and after 11 years of flying it was still in great shape.

Charlie P.

Shim up one side of the servo (or the whole tray) just a "tad" - like with a #4 washer under the attachment points along the side of the lower (*) cable - and the crossed lines won't contact each other. Might be paranoia, but I know several excellent builders who do this so I started. Probably unnecessary with Kevlar, but with wire cables it do make sense.

(*) Lower when the fuselage is right side up, that is. ;-)

ChrisMH

Mike:

There must have been a different engine mount in your kit. Check out the first picture below...there's no way

Charlie:

Excellent idea! I'm definitely going to mount the rudder servo a bit cocked. Thanks.


More Engine Mounting:

1. The engine I'm using (Saito 1.20) compared to the mount included in the kit. I think I'll use something else!

2. Something else. The LHS had this Dave Brown mount (model #120F) which will do the trick. No interference with the cabine supports. I drilled & tapped it for 8-32 bolts.

3. Since I made a new firewall out of a single piece of 1/4" ply, I've lost the centering marks on the original. To recreate them, I first traced the outline of the firewall onto a piece of tracing paper.

4. Then, I can fold the paper on half to find the vertical centerline.

5. Using the plans, I drew in the thrust line. Then, after dredging up my trigonometry (gasp), I calculated the engine offset necessary to put the prop in the center of the fuselage after the right-thrust is built in. Look! I even showed my work! This information is on the plans, but I recalculated it because I wasn't sure exactly what distance from firewall to prop they used. With my distance to prop, I ended up with about 1/64" less offset than the plans show. So no big deal.

Anyway, I'm off to a Christmas party. Everyone have a good weekend!

TBC...

MinnFlyer

My Feedback: (4)

Chris, that's the same mount I hade a YS 110 bolted to, And that has easily as much if not MORE power than a Saito 120.

ChrisMH

Definitely more, I'm sure. I would have followed your advise and used the mount, but, as you can see from the pic, the arms aren't long enough to fit the mounting lugs on the engine.

How did you make yours fit?

MinnFlyer

My Feedback: (4)

You know, I was not seeing the picture correctly. That DOES look smaller.

Here are the Specs of the GP 120 size mount, See if your dimensions match up. If not, contact GP and have them send you the right one

SPECS: Overall length: 4-1/2" Usable beam length: 2-3/4"
Mounting width: Min: 1-7/16", Max: 1-7/8"
Mounting beam width: 9/16" Firewall bolt pattern: 1-7/8"x 1-7/8"

Here's the correct part:

http://www2.towerhobbies.com/cgi-bin...p?&I=LXJ773&P=

ChrisMH

Well, my wife went to visit her sister and took the good camera with her, so these aren't the best.

1. Engine mount blind nuts installed and everything forward of F2, including the firewall, epoxied in place. After it sets overnight I'll reinforce the firewall to fuselage joints and the landing gear support joints with glass cloth and epoxy.

2-3. I made servo mounting rails out of poplar. I didn't use the stock tray because I felt it was kinda flimsy. Also, I prefer to use blind nuts and bolts instead of screws. I'm sure screws are perfectly secure, but don't give me the same happy feeling that I get from nuts and bolts

4-5. Servo mounts installed. As suggested by Charlie P, I mounted the rails on a slight twist so that the pull-pull rudder cables, which will be crossed, won't rub together.

TBC...

AMA 74894

My Feedback: (1)

Hey Chris, not two minutes after my last post I was walking through my shop and saw one of those mounts (The correct one) just sitting on the table. IF you PM your address to me I'll send it to you.

MinnFlyer

My Feedback: (4)

Hey Chris, not two minutes after my last post I was walking through my shop and saw one of those mounts (The correct one) just sitting on the table. IF you PM your address to me I'll send it to you.

ChrisMH

Thanks, that's very generous of you!

I'm covered, though...I bought a Dave Brown mount at the LHS and it's gonna work fine.

Thanks again,
Chris

ChrisMH

Landing Gear

1-2. Landing gear plate. My landing gear will be removable so I'm using blind nuts and bolts to attach it.

Elevator pushrod and rudder pull-pull cables

3. After carefully measuring (several times) on the plans for the location and direction of the pushrod and pull-pull cables, I marked the locations on the fuselage.

4-5. Jig I use to drill for the pushrod outer sheath. Once again, thanks to Paul at Airfield Models for this idea In this case I'm drilling at 10 degrees for a straight shot from the rudder horns to the servo horn.

6. The result of drilling.

7-8. Pushrod outer sheath installed with epoxy and microballoons. The elevator pushrod sheath goes all the way to the servos, the pull-pull sheaths are short pieces just to trim out the openings and to protect the fuse sides from the cables.

9. After trimming and sanding flush.

Throttle pushrod and fuel tank

10-11. Throttle pushrod outer sheath installed. The engine mount I'm using allows a straight shot to the throttle, so no complex linkages necessary. Since the fuel tank installation is essentially permanent (I'm not making a hatch), I don't want any connections in the tank compartment, so I used copper tubing to go straight from the tank to the engine compartment. I'll do an overnight pressure test before sealing the tank in.


TBC...

MinnFlyer

My Feedback: (4)

I like the use of copper tubing on the tank, That's the same thing I do

ChrisMH

Well, I originally saw the idea here on RCU...so chances are it was from you

Chris

ChrisMH

Fuselage

1. Forward bottom of the fuselage has been sheeted. Wow, this was a pain in the buttocks! I think I've used half a roll of strapping tape on this build thus far!

2-3. Turned out fine, though, after the block plane and rough sanding. No filler required for these joints, and all the dents from the clamps I used popped right out after some water and heat. A block plane or razor plane is definitely a necessity on this build. I couldn't imagine the mess & work of removing all that material with just sandpaper! I really love the lines of this plane; it's exciting that they're starting to show up!

4. Cabine wires have been epoxied into the bearers.

5. Almost forgot to pressure check the tank! I put the maximum pressure that I could exert with my lungs into the tank. If it's still there in the morning, I figure that's good.

TBC...