Zor

Visuallizing what you have; I see the engine cowling completely closed except for two small openings each side of the prop at the front.

You need a good airflow to cool that engine. Some opening at the rear bottom of the cowling might be needed. A rule of thumb is to have air exit size 2 to 3 times the air inlet to the cylinder fins.

How do you connect to the glow plug?

On second thought _ _ _ As you wrote "just cleared the cowl", did you mean just cleared the opening in the cowl? or did you mean you did not have to make a cowl opening?

Zor

Jaybird

Zor,

Thanks for the lists. It's all good and I appreciate any "heads-up" kind information.

I saw that one builder drilled through the leading and trailing edge pieces to run a 1/8" rod all the way through the brass tube mounts from front to back for alignment. That seems like a really good modification that I will encorporate.

I did read that most found the cabane mounts don't fit flush so I'm prepared for that. Looking at the pictures in the manual on page 22 and 23 it shows that the mounts are not flush with the cockpit floor but they don't mention doing anything about it. It may just be a change from the drawing.

Worked another three hours last night and finished the other elevator half after picking up the flat stock needed. I found some of the 1/16 x 3 sheets were harder than the others so I used them to sheet the bottom of the stabilizer to give it more strength span wise and for mounting. The other sheets felt like they would form easier too. I noticed when removing the stabilizer die-cut (or die-crunched as my brother would say) that some of the rounded edges had crushed and torn on some of the pieces. It wasn't a problem until I went to sand the taper and the corners "blew out" and broke. I then cut the corner on a diagonal and glued a balsa strip back on and traced the the curve from the other half. The other part did the same thing so I repeated the process.

Jaybird

smithcreek

My Feedback: (25)

Maybe I was lucky, but I did my cabanes like the instructions said it they went together fine. If I remember correctly I was careful tweaking my cabanes before gluing them into the cabane wire holders and even more careful when I epoxied the cabanes into the holder. When I placed the cabane assembly on the fuse I was pleasantly surprised it was dead on. Even if it wasn't though, adjusting incidence would be a very simple matter of raising or lowering the cabane assembly. If you were worried about the cabane assembly not sitting flat on the fuse you could epoxy some triangle stock between the two after it's all together.

Zor

In red by Zor.

Looking for my pics amongst many hundreds.

Zor

Jaybird

Reading ahead in the instructions for lower wing joining (pg 46 - 47) I'm surprised that it doesn't say anything about making sure the the upper wing is level when the fuselage is turned upside down and the tail is vertical. I guess it's a given, but it doesn't even mention it. It also seems odd that they would have you lay the lower wing halves in the fuselage saddle to get the dihedral (assuming there is any) without the center sheeting in place. I guess you just have to trust the interplane struts to position the two wings but I can't get myself to believe it's that easy! Especially when the top wing can tetter-totter on it's center mount.

Also, at the field, what is the assembly procedure for this plane. My Stearman starts with the bottom wing first and my DVII starts with the top wing. The interplane struts on both of them go on last. Again, the manual says nothing to this effect. Probably by that point you have it figured out.

Jaybird.

biplanemurphy

It's been a few years since I built mine, but if I recall correctly, it was joined that way, and worked quite well. Mine's dead on perfect.

Yep....Lower wing, then Upper wing, then interplane struts.....super fast to assemble at the field!

Zor

Some considerations concerning disassembly and reassembly of the wings.

The top wing center should be able to slide out and slide in without any binding.

disassembly _ _ _
1- Disconnect top ailerons linkage.
2- Unlock all three locks under the top wing.
3- Working at the top of the I struts alternatively slide the top wing forward a bit at a time till all three wires are fully back in the wing slots.
4- Pull the top wing off at one end then at the other end.
5- Removing the I struts from the bottom wing is optional.
6- Remove the two bolts at the center of the bottom wing.
7- Disconnect the servos. (identify the servo wires for reconnecting later).

Assembly _ _ _
is the reverse of the above L O L .

Zor

Zor

About the cabane problem.

Found two pictures.
I could not find pictures of the solution
although I know I took some.

Zor

smithcreek

My Feedback: (25)

Cool, thanks for straightening me out. If the plans have problems that necessitate moving the wing 3/8" and the parts have problems with cabane alignment I guess I'll just have to thank God I'm not a very good builder. I must have made enough mistakes that mine went together perfectly. Here's a picture of my lame-o cabane job.

Jaybird

Your assembly looks very well done to me, good workmanship. I've only built the tail feathers so I have no idea how that portion of the build will go. It's nice to have the experience of others to look ahead to try and avoid problems.

I'm a big fan of biplanes and the especially the Skybolt (got to see a Super Skybolt 300 at the BNAS airshow) but not so much of Great Planes kits. I believe a relative of Rube Goldberg (not to be confused with Carl Goldberg) sits with the designers and occasionally whispers..."let's make this just a little more complicated or less user friendly than it really needs to be"... and they listen! I also look at some of the design decisions (I understand that all aircraft are a compromise in design) and scratch my head. Really, you want us to bury the fuel tank in the fuselage never to be seen again? You want it to be held in place forever with rubber bands that will someday deteriorate? (I did notice in the last posted pictures that the tank is held with large zip-ties...good thinking). I see several builders have put a hatch in the top, but you still can't get the tank out or service it. To leave places for fuel residue to enter the fuselage around the landing gear (and for it not to be removeable for repair) and to have gapping holes in the top wing where the upper wire mounts enter it just seems like poor thinking. I don't mind doing detail work to make something look good and function properly, but when I feel compelled to redesign a component because I just can't understand why it's the the way it is, leaves me a little dissappointed.

Okay, enough with the complaining...on with the build. Put in a couple more hours last night sheeting the elevator halves. Case in point....the instructions have you position the elevator over the sheeting such that a corner has to be added to reach all the way to the tip. It also says to cut one edge perpendicular to the long side, but the plans show the hard balsa sheeting laying at an angle. What I did was lay the parts over the plans and draw that line on both sides of the elevator. I then layed the part over the sheeting and found that if I rotated the part a small amount, I could get the whole elevator on without a small triangle added. I transfered the line from the part to the sheet and cut all four sheets so that I could glue the sheeting on aligned with the mark and fit it all on. Small stuff I know, but not hard to figure out.

Jaybird

Zor

Smithcreek,

As I wrote previously, in my build, sitting the base of the cabane on the cabin floor was easy but it gave me a 1 1/2 degree of positive incidence for that top wing.

I did not see that you have told us that after having no problem in your case to sit the cabane base flat on the cabin floor that it resulted for you with the recommended minus one (1) degree of incidence.

Your picture seem to be before you glued that cabane in place.
Can you please confirm you have verified and you do have that minus one degree and the base glued with the inner edge touching the cabin floor in its full length after the final gluing?

Your confirmation much appreciated so we can try to figure what we (me and others) did wrong.

Zor

Zor

Jaybird and readers,

What is happening regarding the 3/8 inch gap seen in my posted picture is that having to rotate the cabane assembly by 2 1/2 degrees to go from plus 1 1/2 to minus 1 degree of incidence the line of rotation is the very front of the cabin floor and that caused the top of the cabane to move forward.

Now with prebuilt I struts exactly by the drawings it brings the lower wing forward by the similar amount at rib 7. We then cannot get the LE and TE of the lower wing to be straight.

We then have to move the top wing toward the rear (backward) to get those LE and TE in a straiight line per drawing. So I had to cut the front of the cabane base to move that top wing backward by about 3/8 inch as seen in the picture.

Of course then some pieces and doublers were epoxied there and tapered wedges epoxied between the cabane base and the cabin floor. Doublers were also cemented on the cabane bases reaching the cabin floor.

It all ended very solid and I have my minus one (1) degree of top wing incidence and verified that.

If I had not seen pictures from others showing the same problem and the same remedy, I would think I am a fool after building models for over 50 years.

Zor

smithcreek

My Feedback: (25)

Yes, my cabanes were ''dead on'', meaning -1 degree. That picture was done after the cabane assembly was glued in place, you can see the epoxy. I put the cabane assembly in place, in the notches in the former and firewall, measured it and it was ''dead on''. I don't remember if my cabane assembly touched the full length, I think it did, but I did put triangle stock along the length of the cabane assembly to add strength anyway.

If I had to guess where people run into problems it's putting the cabane wires in the cabane holders. I carefully tweaked the cabanes and carefully glued them into the holder. I remember having to bend the cross wire a bit to make the cross wire contact both the front and rear wire without pulling the front and rear wire out of alignment. But, even if you don't get it all perfect from the start, you can, according to the instruction manual:

Quote:

Adjust the position of the holder in its
slots, if necessary, until the incidence is correct.
You can do this by cutting the notch in F1B lower
to allow the front end of the holders to drop. If you
have to raise the aft end of the holders off the
cockpit bottom to set the incidence, you should
glue scrap wood in the space between the holder
and the cockpit bottom.

So of course, if you lower the front of the holder the rear is going to come off the cockpit floor, so you'll need to glue in some scrap.

I'm not building my plane now, I finished it early last year and flew it a lot, about 100 flights.


[/quote]

smithcreek

My Feedback: (25)

Well, you found a lot of the glaring "what the heck?" design decisions in this kit. There are a lot more you'll find along the way. Here's how I addressed a few:

-Fuel Tank, I think it would be possible to get the tank out through the fuselage, and I'm almost sure if you planned it out you could make a sliding tray for the tank so it would be easily removable with the bottom wing off. I didn't plan ahead, so if I run into a problem I'll need to cut a hatch, which I think would be just as easy now as it would have been when I was building the plane, or figure out a way to get it out through the fuse.

-Landing Gear, I tossed the gear that came with the kit and made my own from thicker aluminum, I forget either 1/8" or 5/32". I've had some less than perfect landings, no problem. Definitely beef up the landing gear plates and formers in that area. Some people have made their LG removable, that seems to work well also.

-Top and Bottom wing trailing edge are different. One is wider than the other. I don't remember exactly what troubles this caused me, but I remember it had me scratching my head when I needed to join the outer panels to the center panel of the top wing.

I would seriously consider lightening the rear of the fuse, there are some good posts in other threads on this.

Zor

Smithcreek,

Your reply is very much appreciated. Many thanks.

I commented about your picture apparently taken before cementing because I cannot see much glue compared to what I am use to do with filleting the glue. I am not criticising your gluing method so please do not get me wrong.

One reason for my postings was to assist jaybird and I am glad to see you also helping.
One of the main reasons for this situation and also for the manual text (which you are showing) is the accuracy of the cabane wires bends which is not easy to do accurately so they incorporated the text in the manual as a safeguard.

I had to do some bend corrections on the cabane wires to bring the proper angle to fit prior to wrapping and soldering. That had nothing to do with the forward / backward problem. It had to do only with the A shape as seen looking longitudinally.

My tail wheel wire had to be bend corrected. It placed the tail wheel about 10 degrees off vertical and 15 degrees off from the rudder. Being a smaller wire it was easy to adjust the bends. I did not cement the wire inside the rudder. I cemented a plastic tubing in the rudder and the wire is slipped in without any slop. I can remove the vertical tail surface by just slipping it out and back in if I ever have to do repair work. The whole tail assembly is bolted, not cemented. I also have working flying wires on the tail made of 0.030" dia stainless steel wires and small dural alloy ferrules. Same as for the working flying wires between the wings.

Nice talking to you smithcreek.

Zor

Jaybird

Wow! Lots of great information here. The Cabane mount is certainly is an area to go into with knowledge from experienced builders, thanks.

I'm still working on the stabilizer and elevator halves at this point. They are built and sheeted and I'm looking at getting the hinges in. I don't really like the two "Y" pushrods for the elevators especially when they have to stay in place and have covering put around them. My father had a couple of SIG U-Control elevator horns in his collection that are wire in a "U" shape with a metal clevis brazed in the center and two sections of coil springs that slide over the ends, around the bends and onto the straight section (see picture). This would allow be to drive both elevators from a single pushrod in the middle inside the tail of the fuse. I can then make an access area just below the stabilizer (which would also remove material and save weight or be a hatch) and trim the vertical stabilzer post to clear for "up" movement. I think I've got it worked out and will need to trim the elevators to clear the mounting block. I may shape the block a bit more to reduce the amount needed to notch. The pictures show the assembly upside down, if you are wondering.

Jaybird

Zor

Jaybird,

That will work well when the two elevators are flat, not warped in the future due to weathering. You can always adjust the neutral at the servo end accessible in the fuselage above the low wing if that is where the servo is located.

I did that per drawing and I have two threaded clevis under the elevators for future potential adjustments. My stabilizer and elevators are not likely to warp because they are finished with fabric and genuine aircraft dope thus well sealed from the weather conditions.

Suggest to assure that the elevators can fall in both directions by their own weight up to 45 degrees of rotation when not connected to the operating linkage.

Notice it is a suggestion and the reason I believe is obvious.

Zor

Zor

Further to my post 264 _ _ _

I was just looking at the drawing. It appears to me that you will have to cut off entirely the trailing edge piece of the fin (vertical stab if you prefer) in order to clear the elevator horn and be able to have enough up elevator movement. There is only the thickness of this spar to clear the horn joint to the linkage. You could if necessary space the two fuselage sides with more gap by installing spacers above the horn and a small block below the horn where the tail wheel ferrule is installed (if you are using the original supplied material).

The above would increase the very litle width available inside the two fuselage sides to make the connection to the horn.

No doubt you will manage it. The two spring hinges might not be needed at all if the axis of the U shaped wire is reasonable close to the hinge line.

I am also thinking about having to perfectly line up two more hinges beyond the six already on the elevators if the springs are used.

Hey some of these little challenges are fun to solve. No doubt you will.

I am just opening my big mouth while thinking.

Zor

yel914

I thought I might chime in about that buried fuel tank. When I built my Sig Skybolt, which also buries the tank in the fuse, I was concerned. Somewhere I saw an idea of a removeable firewall. So, That's what I did. I have a sub-firewall which is firmly mounted to the fuselage. It is mostly a framework of plywood with some blind nut tabs in the 4 corners. The real engine firewall is a full piece of ply with holes to match up to the blind nuts, as well as holes for fuel lines and throttle cable. Mounted to the back of the real firewall is a tray that holds the fuel tank and throttle servo. To access the fuel tank, I simply remove the cowl and unbolt the 4 screws that hold the real firewall to the sub-firewall. Out slides the engine, fuel tank, and throttle servo(with cable) all at once. Works like a charm.

RCPtero

yel914,

I love the idea of a removable firewall that comes out with the tank, throttle servo and all! Makes it easy to set up all of those things on the bench, then just slide them in and bolt 'em down. Will definitely look at that when I get to that stage of my build.


Tom

Zor

There is an excellent idea applicable to just about any model.

It raises a question.

Why did not any manufacturer think of that ?
I should say "manufacurer's designers".

You deserve congratulations for good brainwork.

Zor

Mako17

Anyone out there in Skybolt land have a complete Sig or GP Skybolt kit they want to part with? I've been building a Cass Engineering Super Skybolt for about a year now. It's the one with Fiberglass Fuse and Foam cored wings. I would really like a full kit though. THanks

Richard

Zor

Richard (aka Mako17),

thanks for a very interesting post showing that some other source of a skybolt kit was available at some time.

Do you know if it is still available and from where?

I have made a search and the Cass Engineering web site did not reveal anything about model airplanes that I could find.

If you can, at your convenience, let us have some information on this kit.

Dimensions?
Flying weight anticipated with which engine you have in there?
Some idea of the reinforcements in those foam wings?
How is the landing gear mounted to the fuselage?
What kind of finishing is on it or will be used?
How are the I struts (between the wings) assembled?
How about the cabane assembly?
Perhqps more pictures detailing the construction.


If this is asking too much then just ignore the questions.
Your valuable time is appreciated.

Zor

Mako17

Zor I really don't have the info on the plane right now, as the plane is in florida, and I'm currently in Iraq working as a contractor. I've searched the evil empire, (ebay) some time ago and found a few on there for sale. To the best of my knowledge this plane was built in the '70's. I bought it from a club member a few years back for $50. If I remember correctly it has a "59 top wing , and 56" or 57" lower wing. Engine range is .60-.91, in the pics it has a old webra speed .91 in it. Tha cabine and landing gear are wire, cabine came pre-brazed in the kit whick is pretty tough, I've since changed the landing gear due to a little too much heat in soldering , to the aluminum type. As far as the finish goes, I have used epoxy and micro-baloons to fair the surfaces, and will paint with something, haven't decided yet. I had to put this project on hold for a while due to the current work situation in the states, There ain't none. Any how if ya have any more question feel free to ask. Oh yeah and cass-engineering doesn't have a web site, I think they have long been gone. Thanks

Richard

Zor

Thanks Richard.
I assumed you were building it at this time.
I had no way to figure this out.

Zor