Crackerjack (oz3320)
About this Plan
Cracker Jack. Radio control scale model of the parasol single seat home built. The subject is a homebuilt plane designed by Pete Plumb in the late 1970s. Plan scale is 1/3. Wingspan 9ft. For OS twin 4-stroke.
Quote: "IT WAS DURING MY FIRST VISIT to Oshkosh in '83 that I saw the full size prototype of the 'Crackerjack'. In '83, the attendances to the EAA annual convention at Oshkosh numbered 14,000 aircraft movements, yes, fourteen thousand during the week, and over 200,000 in the crowd for the first Sunday of the meeting. It must be - is - the most mind boggling show of its kind in the world. There are representative aircraft of all types there, such as World War II, antique, microlight, replica, etc - a most impressive display. However, back to the Crackerjack; the name, by the way, is coined from a make of popcorn. Their trademark is the Sailorboy and his dog, which appears on the fin and rudder, and the designer of the full size aeroplane had their blessing to use it.
The Crackerjack was designed in 1978 by a talented young man named Peter Plumb, who runs a small company called Woodwing Specialities in Tahachabi, California. It is powered by an 850cc flat twin, air cooled 4-cycle DAF car engine suitably modified for aircraft use. Fortunately, it measures just about three times the physical size of the OS twin 120 FS 4-cycle engine - hence my interest in the aeroplane, and at 1/3rd full size it came out just right for my needs. Of course, it can be fitted with any engine of similar power, but I had a Gemini, so I intended to use it!
The designer was very helful to me, supplying drawings and pictures taken during the construction of the full size aircraft. After checking this information, I decided that the model could be built in exactly the same way, using the same materials and methods as for the full-sized aircraft. I made just three main concessions, the fixings of the wing roots to the centre section, the fitting of a 'Cub' type sprung landing gear, and the 'solid' leading edge wing ribs. The remaining structure is a faithful replica.
If you don't fancy building the Warren truss ribs, you can of course cheat, and cut them from sheet balsa, but I suggest you stay with the rest of the structure for lightness, mine weighs 14 lb complete.
All aircraft fly better if they are kept light..."
Direct submission to Outerzone.
Update 07/04/2017: added article, thanks to RFJ.
Supplementary file notes
Article.
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(oz3320)
Crackerjack
by Dennis Tapsfield
from Radio Modeller
February 1985
112in span
Scale IC R/C Civil
clean :)
all formers complete :)
got article :) -
Submitted: 13/09/2012
Filesize: 1087KB
Format: • PDFbitmap
Credit*: anonymous
Downloads: 5677
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NotFound | help
This is a scale plan, but ScaleType is set as NotFound.
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User comments
Hi. I've just found out the name of this plane and thought I'd send you some pictures of the one I have [more pics 006-013].Beck - 04/05/2020
Hello from Malaga (Spain). 30 Years ago I built this beautiful aircraft (1990!) Crackerjack. I want to send some photos of him. He flew an OX MAX Surpass 120. They learned to fly with several children. I liked it so much that now, at 73 years old, I am rebuilding it at 2 m. I want to send some photos [pics 014-018]. Thanks and regards. Sorry for my English translator.
Manuel Iglesias Rozas - 02/04/2021
Hello D. Manuel
Ignacio Gil Saenz-Hermua - 24/04/2022
Hallo, Here is my build of the Crackerjack [main pic, 020-023]! Danke LG,
Werner Forster - 06/12/2022
Hello builders, have you maintained the wing incidence as per the plans? I am asking because the plan reads 2° positive, but when measured, it is drawn at about 4° positive. Wing incidence should be measured relative to the center line of the airfoil, not relative to the bottom. 4°positive seems a bit too much. How does it fly?
JanC - 19/06/2023
The real question is 'how does it measure relative to the tailplane?'
That is the important measure.
If you want to reduce it go ahead but one should assume the designer built/flew it as drawn.
M Hodgson - 20/06/2023
always check plans as they can distorted during enlargment at printers, its easy enough to check angle of incedent once you have your plans enlarged before you start building
Mark - 20/06/2023
download Martin Simons (guru) book and go to page 19 for "angle of attack" vs "angle of incidence" explanation: https://oiipdf.com/simons-model-aircraft-aerodynamics-pdf
Pit - 20/06/2023
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- Crackerjack (oz3320)
- Plan File Filesize: 1087KB Filename: Crackerjack_oz3320.pdf
- Supplement Filesize: 3386KB Filename: Crackerjack_oz3320_article.pdf
- help with downloads
Notes
* Credit field
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Scaling
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