Graupner Cirrus X 3

[neilk]

hmmmm, the webbing (near the root) is marvellously unclear. The combination of the part listings, the exploded diagram (the german booklet), the photographs of actual wings (german booklet) and the plans of the wings themselves are all inconsistent !


I think what they suggest is

rib____ ___________________63(root)___64_____65____66_____ 67_____68_______69_______70______
Main spar front__________________ply_____ ply_____ply____ ply____ ply_____balsa___balsa_______ balsa from here
Main spar rear__________________ply_____ ply_____ ply____ ply____ ply______ -_____ balsa________none from here
part no.________________________98_____ 99_____100____100____100_____ _101____101_________ 101


Aux spar front_________________balsa_____balsa____?_______? _____ ?__ ____-_______ END aux spar
Aux spar rear___________________-_________ -____ balsa___ balsa__balsa__ balsa______ END aux spar
Part no._______________________101______101_____101____ 101____101____101

(darn all my nice layout disappeared [spaces removed] so redid with underscores - hope it makes sense

ply 1mm
balsa 2mm


Where I have ? written, the plans actually show what looks like a web component, although its drawn slightly thinner than the ply
for the main spar and it's not numbered ! The exploded diagram appears not to include it, although they are a bit hard to
negotiate. The wing photo (page 17) apparently shows no web there either (but does show webbing to the rear of the first two
gaps which otherwise the plans indicate to have no web!).

The table of parts also only lists 98x1 per wing (there are two). It lists 99x2 (ok) and 100x6 (ok) and 101x31(which is what
you get with the above layout where the ? are in fact missing, or at least not balsa part 101!

SO I think I conclude no webbing is required at the ? locations.

It probably does not matter much if I add extra ones. I have so much extra weight with spoilers
and ailerons already. I'm also adding a bit of extra support around the rear tube.

The fabled Graupner plans are failing me somewhat here ....

cheers
Neil

[neilk]

Art
what servos did you pick for the ailerons? I'm thinking 9g class micro servos with meta gears, Don't need a lot of torque maybe
at most 1.4Kg.cm (20oz.in).
cheers
Neil

[neilk]

so here is my first wing. had some warping issues after taking off board but steaming and pinning seems to be helping. Art, for your aileron servos, did you attempt to make the servo rod parallel with the aileron or just accept the small angle differential with the line of the ribs. I'm playing around with a HobbyKIng servo cover for the servos but may still make my own...They are a bit big for the 9g servo but I like the aerodynamic rod cover :-)

[neilk]

well it took just about as long to make the aileron hatch (my first one - modelled on Art's) as the rest of the wing !! You can see I have run the wires under the sheeting. I am assuming the wires will never fail but I may need to replace a servo which is removable. This was very fiddly (unlike everything else ha ha). My hatch was not quite flat with the sheeting so I had to sand it down a little (those brown streaks are the ply glue layer I think). Im pretty happy with my new Z-bending pliers !

[ARUP]

Another Cirrus to join the fun! Nice!

[ingrahal]

Neil, sorry for not replying but I haven't been on the forum in a while and I wasn't getting the usual email notices. Your set up looks good to me. As far as throws go, I set up my control surfaces for maximum throw within the mechanical limits. I then setup dual rates for 100% and 50% throws for the maiden. I then adjust as necessary from there.

[neilk]

hey art - no worries. I'm taking break repairing an old model I recently acquired, and then I'll get on with the next wing. I hope it goes faster and the error rate declines !!

[Rich Taylor]

Where can I get a fiberglass fuselage for a Graupner Cirrus? I built one in the early 70s and want to re build one.
Rich Taylor

[ingrahal]

We got ours from a guy in Florida but I don't think he's doing it anymore. Larry tried to contact him a while back with no response. We just got lucky and found the right guy at the right time.

[neilk]

Finally, I have two wings ! Now for the hated covering job....

Also, interested in how people arrange the connection of the wires coming in from the wings
through to the receiver. Think I have to top out my current servo mounts (no way past them....)

[ARUP]

Your wings look great! I use an extension from receiver to wing roots then just connect wing servo extensions from there. Is that what you're asking?

[ingrahal]

Yeah what Michael said. I use a servo extension from the Rx out through a hole in the fuse where the wing mates up. Then connect that to the extension from the servo coming through the root rib and aligns with the hole in the fuse. I connect the two as I slide the wing on the fuse and tuck the wire into the fuse. I used to use fixed connectors epoxied in place that mated as you slid home on the fuse but they would always wear and eventually get bad connections. Connecting the servo extensions and tucking the wires inside has never failed me yet.

[ingrahal]

Neil PM'd me with this question so I posting it here for all to see.

neilk Today, 06:26 PM
Art - if you have a moment, I'd like to see how you routed the writing from the wring root rib down through the fuse and to you're receiver.... It's tricky and I'm sure there are clever tricks/devices I should be considering !
thanks
Neil

No it's actually very simple with my fiberglass fuselage. Are you dealing with the original plastic fuselage?

[neilk]

hi Art - yes I have the ABS plastic fuse. I have routed the wires under the leading edge sheeting ahead of the spar (different to you). So I will need a new hole in the fuse on the nose side of the forward wing rod hole. Here is how my cabin looks (note the pushrods are not in flexible tubes like yours and cannot be as I can't install after the fact) - the interior joining dowel is at about the same height as the wires will come in (it is forward of the wires). so I need to stop the wires from fouling the servos. This is the 'tucking the wires in' part that you describe. I'll do some more staring....

My receiver is currently located forward of the servos in the next chamber.

cheers
Neil

[ingrahal]

I would glue in a plywood tray just above the control rods to keep the servo wires off the rods. Bring your servo extensions for the wings under the elevator and rudder servos and secure them to the support dowel with zip ties and route them out the holes you will drill in the fuselage. Then you can tuck them into the fuse when attaching the wings and the wires will lay on the plywood tray. I noticed your servo wires coming out of the wings are quite long. I would shorten them so there's not so much to deal with.

[neilk]

mm thanks art, i'll do some mocking up. yes the leads were long because I really didn't what methodology I was going to be using !

[neilk]

ok here we are. 1mm ply tray glued in (epoxy) - it sits on a rounded ledge that Grapuner have conveniently supplied !

All wires bundled to the right and cable tied to the dowel (don't think they are going anywhere). slots cut in the front of the fuselage
for the wires from the wings ( by some miracle I seem to have them in the correct place).

So left to do is to shorten the wires form the wings, and then cover them (not my favourite job).

Thanks for the advice Art - it is a good solution

[ingrahal]

Good job Neil!!! That should work.

[neilk]

In contemplating covering the wings (yuck), I concluded that around the spoilers I was not going to have any wood for the shrink film to hang on to. So I added this bit of fairing around the spoiler. I will cover over the spoiler and then cut the shape out. Art, did you do something like this in the end ? I note the metal flange on your spoilers is a bit wider than mine, perhaps you were able to get the covering to stick to that, but I don't have enough, and I didn't think metal would be a good substrate.