S-4 (oz3178)

About this Plan

Abzug S4 (aka Shrimpo). Free flight power model. Ultra thick wing section, 36in wingspan and 241 sqin area. For Elf .09 power.

The Abzug S-4 (oz8934) was first published in MAN Jan 1939. This here is a later redrawn plan from MB.

Quote: "S-4 'Shrimpo'. Old Timer Model of the Month. Designed by Malcolm Abzug. Drawn by Al Patterson. Text by Phil Bernhardt.

No nickname was given to this neat mini gas job designed by Malcolm Abzug and published in the January 1939 issue of MAN. It was billed in the original text simply as the S-4, the 'S' we found out later, standing for 'Shrimpo.'

Unlike the great majority of published gas models of the period the S-4 was not claimed to be a hot performer or a guaranteed contest winner. Instead, the main selling point was its small size and resulting low construction costs, ease of transport, high dependability, and the ability to survive crack-ups with little or no damage, as compared to a larger ship.

Abzug admitted that his midget model couldn't start to compete with its bigger brothers in the performance department, but felt that this was outweighed by the advantages just mentioned. Apparently he was not a very competition-minded fellow.

The S-4 follows pretty much standard construction practices except for the fuselage, which has a distinctive triangular cross-section along its entire length. Another noteworthy feature is the removable engine mount/ignition tray, held in place by two music wire locking pins located flush with the back side of the firewall.

The airfoil is the ultra-thick, high-lift Grant X, the same section used on the big KG-2 and Lanzo Record Breaker (oz427) not the sort of thing you'd expect to see on a little three-footer that weighs under a pound! It turns out that this particular section was chosen for a reason, and that was to make the model fly slowly (20 mph, sez the text), probably by generating a ton of drag.

The original S-4 was powered by an Elf .09, but those few fortunates who own an Elf these days will want to leave it on the shelf and use something a little more common, like an Arden .099, or an Atom.

A Cox reed valve .049 would be a good choice if you don't want to go ignition. For R/C, use something with a little more poop, like a Tee Dee .049 with throttle.

The S-4 spans 36 inches, has 241 sq in of wing area, and must weigh at least 13.4 oz for SAM events. Maximum size engine for R/C events is a .10."

Direct submission to Outerzone.

Here is Malcolm Abzug's S-4, old timer of the month in Model Builder magazine issue 10-80, redrawn by Al Patterson.

Update 31/12/2012: Have changed the spelling in this entry, thanks to Pat McCauley for clarification on this, the correct spelling is Abzug, not Azbug.

Supplementary file notes

Planfile includes article.

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