Optimized Graupner Cirrus Build Log

[GregN]

Someone was cleaning out their garage and gave me a Cirrus fuse. I had to do a little investigating to figure out what it even was. It's a replacement glass one, not the original plastic one. Canopy was not really usable so I will make a solid piece and paint it like I saw in a Flying Models article almost 50 years ago. My plan is to upgrade the original design by making foam wings with socked carbon spars like I would do an XC model or a slope racer, but lighter. Also make some carbon joiners in place wire. Not everything is in place yet, but I have the outline traced off the original plans so I know the dimensions.

I will use the Supra foils, as I still think that's about the best thing out there that is published. Flaps and ailerons for the best possible handling. Will go with all white since after all, it is a scale plane. Right now working on getting templates, then can move to blocking foam.

 

[Red]

Looking forward to following along.

 

[Wayne]

Did you say templates?

Looking forward to your build.

 

[Mucksmear]

Cirrus canopy:

Cirrus : Park Flyer Plastics | Official Website of ParkFlyer Plastics Hobby Accessories - Texas, USA

Park Flyer Plastics Cirrus - This canopy is formed with .030 PETG plastic It measures: 10 1/2 inch long, 3 inch wide , 3 inch tall. This canopy does not fit the Graupner Cirrus.

jse-embroidery.com

 

[GregN]

Figured out the structure. 2.4 oz carbon cloth 0-90 over the whole thing. 2.4 oz "dart" about half way out. 5.7 oz " dart " just over the spar boxes. I will likely glue the two joiner boxes outside the spar and use ply ribs and half ribs to hold them in. Two joiners, in front and back of the spar. Spar is made of .057" x .117" pultruded carbon fiber from Goodwinds. 4 wide at the root and 1 wide at the tip. Kevlar embedded hinges. What a strange world we live in where I can find the first model magazine I ever read in 1978 and look up the article I remember on painting canopies. I will just make something out of foam or balsa to fill the space and paint it with an airbrush.

https://rcbookcase.com/details.php?publication_id=2163&sessionid=8tps1pfl1vic02dp2mpr1isna1

Looks like at least on the web page I can get either 25 or 40 psi foam from Whitecap supply.

 

[GregN]

Templates arrived today. These look very nice. Laser seems equivalent to cnc. Cuts through formica perfectly. Need to drill the pinholes. I guess that means I need to shop some foam.

 

[Wayne]

And it will match @Chris 's counter tops.

 

[GregN]

Got the cores blocked out and the skin sliced off to remove residual stress. Next time is cut the foils out.

 

[GregN]

Note to self use the camera not the phone.

 

[Wayne]

Excellent to see you progressing on the build! Looking forward to seeing this one take shape. I don't know why, but love seeing classic designs modernized.

 

[GregN]

Very happy with the cores. Minimal spackle and a little sanding for the fuzz. Now on to model the wing in Rhino so I can finalize the spars and joiners/ply ribs.