Digester oz6097


Digester - plan thumbnail image

Digester - completed model photo

Submitted to Outerzone: 06/11/2014
Outerzone planID: oz6097 | Filesize: 396KB | Format: • PDFbitmap | Credit*: JeffMac


About this Plan

Digester - Digicon Tester - Radio control sport trainer model for Veco .45 power. 72in span, 1000 sq. in., .45-.61, 4 channel radio. Model # pl-137. Designed by Don Mathes. Featured in RCM 12-64.

Quote: "The Digester is, in many ways, one of the most remarkable models we have even had the pleasure of building and flying. The finest proportional trainer available today, it will also perform the entire AMA pattern with ease. Although the construction is completely straightforward, we will caution the unsuspecting beginner against taking the following article too seriously - we suggest, in fact, that the less experienced RC'er consult one of the old pro's in his local group before tackling this project. Read on and you'll find out why!

The Digester has many desirable features. Among them are such attributes as ease of construction and flying, ruggedness, plus an inherent stability with no loss of maneuverability. In fact, despite its large economy size and light wing loading, the Digester would make an excellent class II competition machine. Its most outstanding trait, however, is that it will not rip, rattle, warp, tear, or smell bad in warm weather. Patent pending.

This particular design came about as an effort to help my good friend Glen Sigafoose of Sig Balsa during a slack season. That, and the fact that as former manufacturers developing radio equipment, we needed a test vehicle for our proportional equipment. Thus, the name Digester - Digicon tester. The fact that there is ample room in the equipment compartments for any radio gear available today can best be illustrated by the fact that we flew this ship utilizing two complete radio systems - the various proportional rigs undergoing flight tests, plus a permanent reed rig with its servos cross coupled by trim bars to the proportional servos.

To date, the original Digester prototype is still flying and has logged well over two thousand flights without any form of mishap. In addition, quite a few RC'ers have racked up their first proportional stick time on this ship, learning to fly consistently and well with art ease that would be impossible on many of the proportional designs currently available.

This is not to imply that the Digester is a goat - the Veco .45 powering the prototype hauls the eight and a half pound ship through the air at a speed of approximately sixty-five mph! In the hands of a good pilot it will do the entire pattern including aileron maneuvers. In the hands of the beginner, it is responsive, yet forgiving. Power requirement is from .35 to .60, with a good .45 recommended.

The initial design of the Digester was accomplished quite scientifically. After carefully considering all of the top designs of the day, we discarded them one by one. Selecting a four foot length of six inch wide sheet from our lumber-mill, we drew the outline of a fuselage on it with ball point pen. Holding this pattern aloft and making noises like an airplane, we decided that the design looked just right. Obviously, therefore, it would fly. Besides, we had a pair of 3-1/4 wheels around for which we had to find a use. So, if you're going to build the Digester, go out and obtain the following:

(a) one proportional system
(b) one twelve-page Sig balsa wood order blank
(c) one rip saw and lumberman's axe
(d) a lease on an empty 5000 square foot industrial plant zoned for light manufacturing
(e) a helluva lot of glue.

You might also consider investing in a surplus parachute which you'll need when you get to the covering stage. Outside of that, the con-struction should offer no. particular problems. Since you obviously won't be flying with two separate radio systems, it may be interesting to note that the Northeast Cornier Bowery Boys made a complete flight evaluation of the Digester and discovered that two regular size cans of beer can be carried aloft with no difficulty - obviously an added plus for this design.

Construction. No problems should be encountered during the construction of the Digester. The most important factor is to have, at all times, an adequate supply of six-packs on hand. The plans, themselves, are self-explanatory. We know, for we drew them with a pencil and warped piece of trailing edge stock so the draftsman would have no excuse for inaccuracies. All he had to do was trace them..."

Direct submission to Outerzone.

Supplementary files

Article pages, text and pics.


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


oz6097 datafile

by Don Mathes
from RCMplans (ref:137)
December 1964 
72in span
Tags: IC R/C
all formers complete :)
got article :)



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

User comments

Don Mathes and Doug Spreng have the distinction of designing the very first digital proportional radio available. Big changes were taking place in the early sixties, old reliable tuned reed systems were on the way out and proportional control was taking its place. But none of them worked, that's why you needed a disposable test aircraft like Phil Kraft's Ugly Stik and Don's Digester. Doug Spreng designed the servo circuit for the Digicon system and it was a revolution, orders of magnitude better than anything else. He never patented the circuit and everybody else in the business immediately copied it. In fact, you can take one of his original servos, change the plug and it will work perfectly in a system made today, the basic principle has not changed in 50 years. But the Digicon had a fatal flaw, the trim would change when you got further away from the transmitter, not much but enough to discourage the pattern fliers who bought it. Somebody came up with a modification to cure the problem but it was too late and Digicon folded.
DougSmith - 30/05/2015
The Ugly Stick is probably the most famous radio control airplane in history. Phil Kraft designed it to build fast and be used as a test plane for his digital radio control systems. But this plane wasn't the first test plane for digital radios. This distinction falls to the Digester [more pics 005-007]. While the Ugly Stick appeared in Grid Leaks in May of 1966, The Digester had made its debut in R/C Modeler in December of 1964. Don Mathes designed the plane to test his own radio system, the Digicon, so the title Digicon Tester was shortened to Digester. The Digester is a three channel plane and the Ugly Stick uses four channels. The plane must have impressed Phil Kraft somewhat for he used the airfoil for his Ugly Stick.
JimHales - 08/05/2017
Add a comment




* 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, 2011-2018.

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.