Privateer (oz4922)
About this Plan
Privateer. Free flight cabin model. Wingspan 87 in.
Note this is not a full-size plan, this is a scan of the original printed magazine pages, with drawings showing formers at 1/2 scale, general layout at 1/8 scale.
Note see Privateer (oz16193) for a redrawn version of this plan at full size.
Quote: "Building The Privateer. How You Can Construct a Sturdy Gas Model That Has Proved to Be a Consistent Contest Winner. Privateer, by Thracy Petrides.
HERE is a superperformer without superconstruction.Not only does it embody the unusual simplicity of square construction, but it also retains the desirable flying characteristics of a streamlined plane.
To substantiate this claim, it flew out of sight after 11 minutes, 25 seconds, at the 1937 National Meet at Detroit. And after being recovered, it later flew for 32 minutes, 50 seconds at another contest. During this flight it drifted only about a mile and at the end glided in for a perfect landing, a few feet from the followers.
From the very first flight the model showed signs of a promising future, and its excellent consistency may be attributed to the well arranged aerodynamic forces. The line of thrust is well up in the fuselage, placing it above the center of lateral area. This set-up promotes spiral stability, which is essential in a gas model. Successful endurance models have a tight spiral climb as well as a tight turn in the glide, the latter being necessary for soaring (the glide, of course, being as flat as possible) and this model incorporates these desirable features.
The correct fin area makes possible the combining of these two flight characteristics. Two rudders were tested before the desired results were obtained. It is hard to believe that ten to fifteen square inches, more or less, in the rudder can make quite a noticeable difference. but these tests have shown this fact to be true.
Construction: Wing: It is advisable to begin construction with the wing as this requires great care. The rib shown is half the actual size, so it must be scaled up by plotting. Make a graph of half-inch squares on cardboard, plywood, or thin metal. Reproduce the section by making a small mark where the airfoil outline intersects each vertical station. Then connect the dots with drawing curves. Draw in the correct spar positions. When this is done cut out the template, and use it to make twenty-seven ribs on 1/8 in medium balsa sheet.
The builder may use his own favorite method of laying out the wing. All sizes of spars, etc for the wing are noted on plate 1. The wing tips are 1/4 in thick, being made by laminating 1/8 in sheet balsa, and attaching them at a 45 degree angle..."
Quote: "Here's a free flight power model from the September 1938 Model Airplane News. Like a number of other designs, it's also called Privateer. Span is 87 inches. Design by Thracy Petrides and drawn by Felix Gutman."
Supplementary file notes
Planfile includes article.
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-
(oz4922)
Privateer
by Thracy Petrides
from Model Airplane News
September 1938
87in span
IC F/F Cabin
clean :)
all formers complete :)
got article :) -
Found online 12/10/2013 at:
http://www.rcgroups.com/forums/showpost.php?p=26330087...
Filesize: 804KB
Format: • PDFbitmap
Credit*: lincoln
Downloads: 2646
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User comments
I built this back in 2006 as an electric R/C and it's still flying today [pics 004,005]. I thought your site could use a few more pics of it. Love the site, BTW.Mark Miller - 14/09/2020
Some photos of a Privateer recently built and flown from your plans [main pic, 007-009].
Tom Ryan - 15/09/2021
One more pic of the Privateer. Has a great glide [pic 010].
Tom Ryan - 12/11/2021
Some more Privateer photos and videos here: https://tinyurl.com/lgbfjblgbfjb
Tomás - 19/06/2022
Hello Mary, Please find enclosed a photo of my Privateer plane [pic 011], plan oz4922. Powered with a Saito 40 four stroke engine and such an angel to fly. Regards,
Bryan Treloar - 12/03/2026
This guy really knows what he's doing, the only one of the Old Timers who understood the problem. Just what was the problem? That's right, it was the dreaded Death Spiral, the demise of many a new ship back then. You wanted the model to fly in circles so you could keep it in sight, so you gave it a little rudder trim and set it on its way. It took off, started a bit of a left turn, then slowly increased its turn until it contacted Earth. Lightly built, it was history. Dozens of theories explained what happened, none of which worked. First they tried increasing the size of the fin and rudder, sometimes double what it was, didn't work. This design gets it right, the relationship between dihedral and fin size. More dihedral and a DECREASED fin area did the trick, a stable climb followed by a nice glide, gentle landing. You'll notice the fin and rudder is pretty small compared to most old timers. Leave it that way for good results. It will turn just fine with rudder only and right itself when disturbed. As usual, a few changes might help. Added nose length might compensate for electric power, and landing gear could be moved back for better ground handling. I like the laminated balsa tips for all surfaces, and I would use larger spruce spars instead of balsa. But these are details, make it your own.
doug smith - 14/03/2026
Here is a picture [pic 012] concerning your Privateer plan oz4922. It's a real nice plan but unfortunately not full size. Another Privateer is available but not as detailed as the original one. If you want to use the original drawing, there is a way. By measuring the plan and comparing dimensions, it was obvious the plan was scaled 1/8 size. Yes, we could print it multiplied by 8 but it takes a whole bunch of paper. What I did was crop out small portions and then print each piece in "tiles", printed at 800%. See photo of 4 sheets taped together to form the fin and rudder. 9" indicated on the print measures exactly 9". Some of the other dimensions are close, but may differ from the original scan. I used PDF GEAR (free) to crop out various details of the plan, then printed it at 800%, taped it together. This method will work with any plan available only as a small scan from the magazine. You can get all the details from the original without having to print the whole large sheet. Sounds complicated but was actually pretty easy. That's what we do, we're modelers, we solve problems.
Doug Smith - 14/03/2026
Doug: The Privateer's tail and dihedral are pretty typical of pre-Zipper designs. The latter have much smaller fins and pronounced dihedral. They don't lend themselves well to radio-assist.
Trial & error explained more of the successful designs than theory. I remember asking Sal Taibi how he came up with the proper size fin. "Well, I make the prototype out of sheet and kept trimming it down until the model started to dutch-roll. Then, I added a little bit back"
TomRyan - 15/03/2026
I love trial and error, my favorite method. Trail and error always works so long as the number of trials exceeds the number of errors by one. Years ago I flew rubber powered models. Someone would always ask how many turns do you wind into the rubber motor? My answer: Wind it up until it breaks, then back off one turn.
Doug Smith - 16/03/2026
LOL... Doug wins!
RC Yeager - 16/03/2026
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- Privateer (oz4922)
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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
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