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Old Feb 09, 2012, 10:14 AM
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Ljubljana Brnik, Slovenia
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Build Log
Cirus hs-62 (1:3,5)

I was searching for a vintage sailplane made in our ex Yugoslavia, with goal that it is not already done as an RC model. Almost all of them are even done, or on the working bench or in stage of designing, by my RC model fellows....

So I came to the CIRUS HS-62 who was obviously waiting for me.


Some data for original Sailplane:

Designer: Nenad Hrisafovic
Year: 1962
Wing span: 17m
Wing area: 18,38m2
Fuselage length: 8,66
Weight: 378 kg empty, 558 with two pilots.
Glide angle: 28 at 88 km/h
Construction: Fuselage welded tubing covered with fabric, Wing wood plywood&fabric covering
Purpose: School biplace sailplane

Prototype evolved as some modifications were done on the main landing gear, on elevator and cockpit belly.
In two years, glider was redesigned with fully wooden oval shaped fuselage, named CIRUS HS-64.

I will build the prototype, 1:3,5 scale model.
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Old Feb 09, 2012, 10:45 AM
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Ljubljana Brnik, Slovenia
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Story about how I make Cirus drawings

Unfortunately, only a small and badly drawn 3 view of Cirus was available in old books. It was no way to use it for making plans for the scale model. To many "missaligments" on the drawing.
Side and top views did not match, left and right wing drawn by different sweep...




I was devastated, until I heard that designer of this sailplane is stil alive and it was retired chief designer of French rockets Aeriane.

I decide to write him an email, asking him for any possible help, to find out exact proportion and possible other details for his Sailplane.
Of course I expected, that "rocket" scientist will not bother with a small guy playing with RC planes..... BUT, I recieve a very pleasant respond from him, giving me hand and help in any way.

Unfortunately, he told me that in 1965, he escape in France as there was no job for him anymore in Yugoslavia.
He worked at Belgrade faculty as an asistent.
For that reason, also CIRUS sailplanes went slowly in shade and no technical documentation is available no more. I heard that one Cirus HS-64 is still (luckily) stored somwhere in basement of Yugoslav Aviation Museum.

As Mr. Nenadovic came to France with just some necessarities, he was able to take wih him only a small booklet, User manual and description of Cirus and some photos taken during assembly of the prototype.

Based on that data, we actually start with making drawing of Cirus "from scratch", including its internal structure. I think, we did a great job! Me making drawings, and Mr. Hrisafovic correcting them with his beautiful done sketches and remarks!

We came to the drawings suitable for using them for making very detailed scale models.
(Martin Simons would be proud of us! )


This is the final 3 view and structural drawing of CIRUS HS-62 Sailplane.

Some more photos of the Cirus (property of Aeroclub Sarajevo):
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Old Feb 09, 2012, 11:21 AM
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Ljubljana Brnik, Slovenia
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Making of the scale model

As this sailplane covering was not transparent internal structure was not visible trough (most vintage sailplanes does), I decided to go as fast as possible toward flying model.
Decision was: sandwich wings and tails, composite fuselage!

Wing will be made as styrofoam core, sheeted with obeche, laminated with glass fabric and filled, sanded and painted.
Horizontal tail and rudder will be made same as the wing.
Fuselage will be made in "lost foam technique".
There will be an imitation of welded tubing structure in cockpit, but of course made from painted round wooden dowels.

I started with making wing cores first.
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Old Feb 09, 2012, 11:45 AM
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What a great project, looking forward to seeing this one develop.
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Old Feb 09, 2012, 01:08 PM
yyz
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Very few people do scratch builds with this kind of research and dedication. You should be really proud of this effort and the great story behind your work. Fantastic!

Is that an HQ section you're using on the wings?

Subscribed,

Mike
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Old Feb 09, 2012, 01:25 PM
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Ljubljana Brnik, Slovenia
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Quote:
Originally Posted by yyz View Post
Very few people do scratch builds with this kind of research and dedication. You should be really proud of this effort and the great story behind your work. Fantastic!

Is that an HQ section you're using on the wings?

Subscribed,

Mike
Thanks for such nice words!

Yes it is HQ section. I get suggestions for the wing airfoils from Dr. Helmut Quabeck itself.
Root: HQ 3,5-14
Tip HQ 3,5-13

Mitja
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Old Feb 09, 2012, 02:34 PM
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Subscribed :]
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Old Feb 09, 2012, 02:52 PM
DS will change your life
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Danmark, Nordjylland, Sæby
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Cool
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Old Feb 09, 2012, 04:35 PM
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Nice work, Mitja.
Subscribed!

Bostjan
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Old Feb 10, 2012, 05:07 AM
Upwardly Mobile
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Nice looking sailplane,
Subscribed Mike.
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Old Feb 11, 2012, 11:39 PM
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so are we sticking wood yet?
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Old Feb 11, 2012, 11:53 PM
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Ljubljana Brnik, Slovenia
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Quote:
Originally Posted by Big Nuts 181 View Post
so are we sticking wood yet?
There will be very low wood content in the model... only wing and tail sheeting and a few formers in the central part of the fuselage.
At the moment, very low temperatures dont tempting me to be in workshop.
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Old Feb 12, 2012, 05:53 AM
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Hahaa crank up the gas heater put on an extra pair of long johns..... She'll be rite. Looking forward to seeing things cone together.
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Old Feb 12, 2012, 07:32 AM
Vintage wood is the best!
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Exactly......first order of business is to get some heat in that shop and get cracking on building!
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