Ace 4-20 (oz8666)


Ace 4-20 (oz8666) by Doc Mathews 1986 - plan thumbnail

About this Plan

Ace 4-20. Radio control sport model.

Quote: "Another member of ACE's tremendously successful family of planes designed exclusively for four cycle engines, the 4-20 offers the best of both worlds: economy and performance. The small size of the kit and the engine required automatically reduce the price itself. Performance wise the 4-20 uses the same basic design as the great flying 4-40 Bipe (oz6271) and 4-60 (easy to maneuver yet capable of all aerobatic stunts) and the small four stroker engine still gives you that elusive power and quiet purr."

Direct submission to Outerzone.

Quote: "The 4-20 was never an immensely popular kit, but with the increased interest in mid sized electric planes it seems that there is a lot more excitement about the 4-20. When the kits come up on ebay they always bring a high price. A lot of people want this plane ...I've been looking for this one a long time. It was included in a box of junk I bought from a friend."

Update 7/12/2023: Added kit instructions, thanks to Bill Powell.

Quote: "Assembly Manual. ACE 4-20. Designed by: DB 'Doc' Mathews.

Introduction: The 4-20 is a member of Cap'n Eddy's Stroker Squadron, a family of planes designed specifically for modern day four cycle engines. The 4-20 retains all the virtues of the 4-40 and 4-60, even though small in size. Smooth aerobatics plus the excellent ground handling and takeoff/landing qualities are retained in the small version. More importantly, the 4-20 handles much better in moderate winds than most other airplanes in it's size class.

The 4-20's flight envelope is broad enough to allow docile trainer-like flying with a forward center of gravity; it becomes nicely aerobatic when the OG is moved rearward and the throws are increased. The model flies an its Lifting surfaces (as an airplane should). It is not an overpowered projectile that uses brute power for flight. As a consequence, the maneuvers are slow and stately as opposed to abrupt and violent - many pilots who have flown the small version prefer it over the larger models due to being able to keep it within tight field confines, plus the emotional and finanical investment is minimized, making flying more relaxing.

Now that we're sure you're anxious to start, we won't praise this airplane any more. You'll find out an the first flight we're talking about!

Read through the instructions and familiarize yourself with the parts. Note that the wing is the only full size plan. Some have commented that they'd rather see full size plans and we can appreciate that but full size plan are certainly not necessary to build the plane and their printing cost is very high which would have to be reflected in the kit cost. The only reason for full size plans would be to cut out new parts in case of a crash. If you feel this may be your case, it may be wise to trace off all the parts and file them in case disaster strikes. Of course, we'll be glad to sell you a new kit as an alternative... "

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

Ace 4-20 (oz8666) by Doc Mathews 1986 - model pic

  • (oz8666)
    Ace 4-20
    by Doc Mathews
    from Ace RC
    48in span
    IC R/C Kit
    clean :)
    formers unchecked
  • Submitted: 27/04/2017
    Filesize: 1468KB
    Format: • PDFbitmap
    Credit*: Balsaworkbench
    Downloads: 3547

Ace 4-20 (oz8666) by Doc Mathews 1986 - pic 003.jpg
Ace 4-20 (oz8666) by Doc Mathews 1986 - pic 004.jpg
Ace 4-20 (oz8666) by Doc Mathews 1986 - pic 005.jpg
Ace 4-20 (oz8666) by Doc Mathews 1986 - pic 006.jpg
Ace 4-20 (oz8666) by Doc Mathews 1986 - pic 007.jpg
Ace 4-20 (oz8666) by Doc Mathews 1986 - pic 008.jpg

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

User comments

Hi Steve, So I have attached the manual PDF and a couple of pics of the finished plane [main pic, 065, 007]. Powered by an OS 26FS, plenty of power. Thanks again,
Bill Powell - 07/12/2023
I built the Ace 4-20 in an attempt to fly off-water decades ago [pic 008]. However, it had only been flown off-ground. It had been powered by O.S. FP-20, FS-48, and .32F. On my to-do list is to convert it to electric powered.
Max Li - 10/12/2023
Add a comment



Download File(s):


* 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.