Utility Special (oz1819)

 

Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - plan thumbnail

About this Plan

Utility Special. Free flight rubber model. From Popular Science, May 1937.

Quote: "This new flying model won't crack up. Utility Special, by Frank Zaic.

SPEEDY and extraordinarily stable, this new streamline model air-plane, known as the 'Utility Special', is a fine design to open the season's flying. On normal power it will average flights from half a minute upward, and by the addition of a few extra strands of rubber it can be made to buck stiff winds or fly at racing speed. The materials cost about 50 or 60 cents.

Fuselage: Laminate 1/64-in balsa sheets for the entire set of bulkheads. When the cement has set, tack each bulkhead to a drawing board and mark the outline, longeron slots. and stringer marks. Trim and cut the slots with a razor.

Select four matched longerons. Mark the bulkhead spacings while all are held together. Cement longerons to bulkheads 4 and 5. Let the cement set well. Then cement the rest of the bulkheads, work-ing from center towards ends. Keep the fuselage lined up. The 1 , 16-in. square stringers arc next cemented so that they are superimposed above the marked points on the bulkheads. Trim longerons flush with front bulkhead, and cement an extra sheet without slots in front of them. In rear, trim longerons and stringer to a point. cement them together, and cut on slightly to accommodate trailing edge of stabilizer. The 1/64-in sheet covering is applied after stabilizer and front plug made.

Landing Gear: Make the laminated platform and cement to bulkheads and stringers. Cut and bend the wire struts. Cement them to the platform and reenforce with wire staples. After the cement has set, the lower wire extremities are bound to-gether very tightly with rubber bands. The streamline 'pants' are made by cutting the sides and center to shape and cementing them together. Standard hard-wood wheels are used. Set the pants parallel to the fuselage and fasten them to the wire with a generous amount of cement. To line up landing gear, cement a long strip of balsa on top of the center longerons just in front of the bulkhead and measure up from table to each end. Keep the strip in place to check the wing and stabilizer during the later assembly.

Wing: This is built in one piece, but the center or flat portion is made rather loosely as it has to be taken apart and reassembled on the fuselage. Draw a full-size plan. Cut all ribs to same size, and shape the leading and trailing edges. Now superimpose the spars over the full-size drawing and hold them with pins while the ribs are tapered and cemented. Note that the spars are cut in three sections. Use cement generously while placing ribs. Be sure to shape tips well to reduce drag.

The dihedral angle is made by raising the wing tips 2-1/8 in and beveling the center and the outer-panel spars at their junction to the correct angle for a butt joint.

Separate center section of wing from the assembly and let one rib hold the spars to correct spacing. Pass the spars through the fuselage stringers and cement the front spar to bulkhead 4. Make certain the spars are parallel to the line-up strip. Replace the rib, and also cement the ribs which nestle against the fuselage. The outer two panels are joined to the center section. Check the dihedral by noting the distance from tips to table; also correct any difference in incidence. If you are doubtful of the cement, strengthen the joint with a bamboo sliver..."

Supplementary file notes

Planfile includes article.

Corrections?

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

Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - model pic

Datafile:

Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - pic 003.jpg
003.jpg
Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - pic 004.jpg
004.jpg
Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - pic 005.jpg
005.jpg
Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - pic 006.jpg
006.jpg
Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - pic 007.jpg
007.jpg
Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - pic 008.jpg
008.jpg
Utility Special (oz1819) by Frank Zaic from Popular Science 1937 - pic 009.jpg
009.jpg

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

User comments

Here's a few pictures of the 'Utility Special' I recently built from plan oz1819 [main pic, 005-009]. Build was straightforward, finish is all tissue and was inspired by the TWA Constellations flown in the 1950s. Models weighs ~34g without rubber, and flew well in its first outing on 2x18" loops of 1/8" rubber (~6g motor weight).
Flight video at: https://www.youtube.com/watch?v=C4lvZmXgbho, build thread on RCGroups at: https://www.rcgroups.com/forums/showthread....
Thanks for all you folks do to keep these plans available!
Mike Kelly - 06/10/2020
A masterpiece...
pit - 06/10/2020
Wonderful!!
Roberto Grassi - 06/10/2020
Add a comment

 

 
 

Download File(s):
 

Notes

* 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.

Scaling

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.