Square Soar 72 (oz1245)


Square Soar 72 (oz1245) by Lee Renaud from Airtronics 1975 - plan thumbnail

About this Plan

Square Soar 72. Radio control thermal glider. Plan also shows optional power pod for .049 power.

This plan is branded as from Airtronics, but also carries the legend: "Cox Hobbies Inc. 1977 Plan no. 91011700".

Quote: "The Square Soar is an easy to build R/C sailplane designed for the novice. The straight forward construction is similar to many free flight models and provides a rugged crash-resistant structure so important for surviving the first few flights. The constant chord wing and simple box fuselage make building and covering the model a simple task, even for the first-time modeler.

Don't let the appearance fool you. This model flies very well and will provide outstanding flights. Designed for thermal flight, it is also an excellent slope model in light to moderate wind conditions. The Square Soar has also been very successful as an electric powered sailplane, even at weights up to 45 ounces.

The model can be built in four different versions including a V-tail. This permits easy experimentation to compare the performance of dflerent configurations. For all around performance and maximum stability, the conventional tail, polyhedral wing version is recommended.

This kit includes all wood parts and special hardware items required to build the model. Adhesives, covering materials and standard hardware items for the radio installation are not furnished. These are readily available from your hobby dealer.

No special tools or jigs are required. Any smooth flat sur-face, into which you can push pins, at least 36 in long and 8 in wide is required to assemble the model. Use Handi-Wrap or similar material to protect the plans during construction..."

Update 23/03/2018: added build instructions, thanks to Paul Rinde.

Update 23/03/2018: replaced this plan with a much clearer scan, thanks to Paul Rinde.

Direct submission to Outerzone.

Update 02/08/2018: Added PDFvector plan tracing and CAD files, thanks to AlanSinclair.

Update 14/01/2021: Replaced the CAD zipfile with a revised version, thanks to AlanSinclair.

Quote: "Hello, Happy New Years! Since you posted a very clean set of plans for the Square Soar 72, I finally went back and revisted the CAD drawings, found that the original set of plans I worked from were quite distorded with regards to the horizontal stab. So here are the revised PDF and DXF files... Have a great day,"

Update 19/04/2021: Added review from RCM, thanks to HarryKirkland.

Quote: "RCM Product Test: Square Soar, from Cox Hobbies Inc.

The Square Soar 72 is a 72 inch span Standard Class Sailplane designed by Lee Renaud and manufac-tured by Cox Hobbies, Inc. Designed both as a basic trainer and as a sport sailplane, the Square Soar 72 has 504 square inches of wing area and can be built either with dihedral or polyhedral.

The fuselage has plywood sides and bottom front with the remainder of the fuselage being of conventional balsa construction. The wing has hardwood spars and leading edge with balsa center section, ribs and trailing edge. The rudder is sheet balsa while the stabilizer is of built-up balsa construction. Hardware included in the kit-consists of rudder and elevator horns, devises, hinges, pushrod and threaded pushrod attachments, tow-hook, and blind nuts.

One unusual feature of the kit is that it can be built in different configurations. For example, you can choose either dihedral or polyhedral and select either conventional rudder and stabilizer or a V-tail. The polyhedral wing with conventional tail is recommended for the novice as the ideal trainer.

In addition, an optional power pod can be installed for power assisted launches. A Cox .049 engine is recommended for this purpose.

We found the Square Soar 72 an easy building, sturdy glider designed to take the bumps. Follow the fuselage construction sequence outlined on the building instructions in order to minimize the chances of coming out with a 'banana' shaped fuselage. Adding the washout in the wing tip panels can't be emphasized too strongly in order to produce a stable flying glider.

Our prototype weighed 25 ounces for a wing loading of 7.14 ounces per square foot. It was covered wth Mono-Kote and trimmed with Bridi striping tape. The optional power pod shown in the photograph [pic 006] was coated with resin and painted with dope to match the MonoKote. Two channels of a Cox-Sanwa radio was used for control.

The Square Soar 72 is a good, stable flying glider with or without the optional power pod. It is Ideal for flying out of school grounds or on the local hill in a light breeze. "

Supplementary file notes

Instructions. 8 pages inc photos.
Previous scan version.
VectorPDF plan tracing.

CAD file

This plan is available for download in CAD format.


Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction

Square Soar 72 (oz1245) by Lee Renaud from Airtronics 1975 - model pic


Square Soar 72 (oz1245) by Lee Renaud from Airtronics 1975 - pic 003.jpg
Square Soar 72 (oz1245) by Lee Renaud from Airtronics 1975 - pic 004.jpg
Square Soar 72 (oz1245) by Lee Renaud from Airtronics 1975 - pic 005.jpg
Square Soar 72 (oz1245) by Lee Renaud from Airtronics 1975 - pic 006.jpg

Do you have a photo you'd like to submit for this page? Then email admin@outerzone.co.uk

User comments

This was my first glider back in the 1978. It's a very rugged glider and not the least bit fragile with the spruce leading edge, main spar and properly built. Mine took a lot of abuse including flying into the back window of a station wagon multiple times (intentionally). I have a NIB Square Soar 72 kit and can try to copy the instructions if I can get my scanner talking with my computer.
Scott - 22/06/2013
Steve, Mary, Find attached a couple of photos of my Airtronics Square Soar built in the late 1970s [main pic, 005]. Find attached a review from RC Modeler magazine. The Square Soar was a quick to built sport sailplane which was good to fly in school yards or small sites. As usual the Airtronics kits were the best of their day and this was no different. The wood was great and the cutting second to none.
Harry Kirkland - 19/04/2021
Add a comment



Download File(s):
  • Square Soar 72 (oz1245)
  • Plan File Filesize: 1127KB Filename: Square_Soar_72_oz1245.pdf
  • Supplement Filesize: 1786KB Filename: Square_Soar_72_oz1245_instructions.pdf
  • Supplement Filesize: 644KB Filename: Square_Soar_72_oz1245_previous.pdf
  • Supplement Filesize: 689KB Filename: Square_Soar_72_oz1245_review.pdf
  • Supplement Filesize: 737KB Filename: Square_Soar_72_oz1245_vector.pdf
  • CAD Zip Filesize: 301KB Filename: Square_Soar_72_oz1245_CAD.zip
  • help with downloads


* Credit field

The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.


This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.


Terms of Use

© Outerzone, 2011-2021.

All content is free to download for personal use.

For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.

Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.