Liberty Sport


Liberty Sport - plan thumbnail image

Liberty Sport - completed model photo

Liberty Sport  
by Dick Graham
from Sig
57in span
Tags: IC R/C Biplane
formers unchecked

This plan was found online 10/11/2014 at:
Outerzone planID: oz6112 | Filesize: 1542KB | Format: • PDFbitmap | Credit*: Gerald, JPM


About this Plan

Liberty Sport - Radio control sport model for .45 to .60 engines. Kit # RC-33. Note this plan is missing plate 2, so this plan is incomplete.

Update 16/11/2014: Added supplement file inc (low res) page 2, thanks to JPM.

Supplementary files

Alternate version of the plan. This one is low res, but does have both pages.


Did we get something wrong with this plan? That happens sometimes. Help us make a correction


User comments

It is a pity that original sheet no 2 of plan is missing which covers horizontal tail plane and lower wing to 1:1. I have built Liberty Sport in 1984. It's still in flying condition and looks exactly like the plane in photo by Dick Graham. Sig plans were good and accurate to build. I fitted OS .60 4-stroke which was pretty adequate. The only actual modifications made was to give 1 deg negative incident for flat bottom of Clark Y aerofoiled top wing when fixed, to reduce total of 4 deg decalage of wings created by Clark Y aerofoils when bottoms were on horizontal level. Likewise to datum line to 3 deg and engine inclination down and right 1,5 deg. With original SIG set-up plane tends to jump up every time gas was implemented in the air. Landing of the plane was just a magnificent job to do with modified set-up. She was steady and calm and sit on 3 points. I used CG at point of 7 mm back from leading edge of lower wing which was about 25% point on MAC, calculated based on combined plan view of wings seen from above the wings and indicated by SIG. Lower wing is straight and few cm shorter than top wing and sits as shown on sheet no 1 "side view". It has couple degs of V. Wing N-struts are also angled outwards with some 15 deg. Ailerons only on lower wing. For 4-stroke .60 engine with carburetor behind installation, if I built plane today I would move firewall a bit backwards to give space for carburetor, its control and fuel lines. Top wing is horizontal with no V and swept backwards as shown. Center section which is at 90 deg to centerline of the fuselage is shown correctly in plan and covered by balsa sheets. Both wings have the same size of Clark Y aerofoil. I just wonder should I prepare sheet 2 to show lower wing and horizontal tail based on my plane built from SIG kit? Kind regards from Finland.
EinoRonkanen - 20/11/2017
The supplement file has a low resolution version of page 2. But if you can produce a drawing that has more detail, that would be great, thanks.
SteveWMD - 21/11/2017
Regarding my comment: I did modify aerofoil to be Clark Y. Aerofoils in drawings are modified Clark Y (tail lifted) to give less lift when at 0 deg incident.
EinoRonkanen - 01/12/2017
If someone wants to build Liberty Sport in larger scale than 1:6 it is practical to know wingspan of the top wing of 1:1 protype is 8.7m when scaling the sheets.
EinoRonkanen - 01/12/2017
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