IMAC One Design (oz10576)


IMAC One Design (oz10576) by Matt Mrdeza 1995 - plan thumbnail

About this Plan

IMAC one design. Radio control scale aerobatic model.

Quote: "One-Design Aircraft for International Miniature Aerobatic Club Competition. Design by Matt Mrdeza, mods by Darrel Stebbins.

IMAC, following the lead of its full-scale counterpart, has developed a 1/3 scale model of the International Aerobatic Club's new One-Design acrobatic airplane. IMAC's mandate, as promulgated by its charter members, is to replicate full-scale aerobatics with R/C aircraft. The planes flown in IMAC competition are required to closely resemble aircraft that have been flown in full-scale competition. Minor deviations are allowed, eg a 10% variation in fuselage length, control surface area, etc and 20% reduction in fuselage height and width.

There are presently four classes of competition in IMAC: in ascending order of difficulty. Basic, Sportsman, Advanced, and Unlimited. The acrobatic sequences flown are virtually identical with the sequences of the corresponding full-scale classes. The new class, to be known as the One-Design class, will be added to the competition schedules as sufficient planes are built to justify a separate competition sequence. Meanwhile, the One-Design may be flown in any of the present classes.

The One-Design concept is an attempt to 'level the playing field' to standardize the aircraft so that the winner of the competition will be determined by flying skill rather than (to use an auto racing term) 'cubic dollars'. In MAC, the One-Design aircraft configuration must match exactly the plans herein reproduced, and the maximum engine dasplacement is established at 1.20 cubic inches. Type of construction, materials, and weight may vary; but exterior must follow the outlines shown on the official IMAC One-Design plans.

Matt Mrdeza was asked to build a scale model from the original plans of the IAC One-Design, to check the design parameters of the full-scale plane. He built a 1/3 scale model, working closely with Dan Rihn, designer of the IAC plane. The plane flew very well, with all moments and distribution of surfaces acting as had been predicted. A special acrobatic airfoil was designed for the plane, which also proved to be exactly what the designers had hoped for. Matt subsequently brought the model to the attention of IMAC and the design was reviewed with special attention to the modifications suggested by Matt after flying the scale model. lMAC suggested scaling up to a 72 in wingspan, narrowing the fuselage at the front by 20%, decreasing the fuselage height somewhat, lengthening the fuselage by 10%, and adding area to the vertical fin and rudder. These changes were incorporated into the plans, and the prototypes built to the modified specifications.

Three prototype planes have been built, the first a test-bed plane to check out the basic features of the design. and the second to serve as the construction model for this article. The third, built by Matt Mrdeza, was built from the plans but included a smoke system and a much larger engine. This model would not qualify for One-Design competition. but would qualify for any of the other four classes of 1MAC competition.

The Prototypes have been flown extensively, and seem to exhibit no undesirable characteristics. #1 is being flown at 11-lbs with a Super Tigre 90; #2 at 12-lbs has an ASP 1.08 installed; and #3 at 17-lbs. has a 3-W35 ignition engine.

Construction is mostly built up balsa and plywood. The first step is to create a kit for yourself..."

Supplementary file notes



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

IMAC One Design (oz10576) by Matt Mrdeza 1995 - model pic


  • Rihn_DR-107_One_Design | help
    see Wikipedia | search Outerzone
    Test link:
    search RCLibrary 3views (opens in new window)

    ScaleType: This (oz10576) is a scale plan. Where possible we link scale plans to Wikipedia, using a text string called ScaleType.

    If we got this right, you now have a couple of direct links (above) to 1. see the Wikipedia page, and 2. search Oz for more plans of this type. If we didn't, then see below.

    ScaleType is formed from the last part of the Wikipedia page address, which here is
    Wikipedia page addresses may well change over time.
    For more obscure types, there currently will be no Wiki page found. We tag these cases as ScaleType = NotFound. These will change over time.
    Corrections? Use the correction form to tell us the new/better ScaleType link we should be using. Thanks.

IMAC One Design (oz10576) by Matt Mrdeza 1995 - pic 003.jpg
IMAC One Design (oz10576) by Matt Mrdeza 1995 - pic 004.jpg
IMAC One Design (oz10576) by Matt Mrdeza 1995 - pic 005.jpg

Do you have a photo you'd like to submit for this page? Then email

User comments

The "one design" concept was an idea that never gained much popularity. The airframe design was ok in its day, but isn't up to today's standards.
Chuck Lackey - 17/11/2021
That's equivalent to saying "Propellers in WW I were wooden fixed-pitch type, but those aren't up to today's standards."
Miguel - 18/11/2021
Add a comment



Download File(s):
  • IMAC One Design (oz10576)
  • Plan File Filesize: 728KB Filename: Imac_One_Design_RCM-1183_oz10576.pdf
  • Supplement Filesize: 1686KB Filename: Imac_One_Design_RCM-1183_oz10576_article.pdf
  • 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, 2011-2024.

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.