Flattop (oz13210)


Flattop (oz13210) by Dave Hewitt 1992 - plan thumbnail

About this Plan

Flattop. Free flight power model. For 1/2A engines.

Quote: "Dave Hewitt was a successful free flight competitor from the Portland area in the 1950s. This model, the Flattop, at one time held the National 1/2A AMA Gas Record. What is especially unusual for this design is that its center of gravity is located 2-1/2 to 3 inches behind the trailing edge of the wing. The model is built to be very light, so that the climb is improved even with the rather tepid engines used during the early 1950s.

A couple of tips about the model - just in case you decide to build one. Choose the very lightest wood you can for construction. The original designs weighed in at 4 oz.

Second, trim the model so that it has a tight right turn in the power phase - it should spiral in the climb.

Finally, the glideturn also should be very tight. Circles of 50 to 100 feet are the goal. The object of a tight circle in the glide is to eliminate any tendency to stall, which could be disastrous in a free flight with such an aft CG.

So, if you are looking for an unusual 1/2A design, check out this three-view, look over the 1953 Zaic Yearbook (if you can locate one) and consider building the Flattop. I am."

Direct submission to Outerzone.

Update 12/08/2021: Added pdf with original 1953 drawing from Zaic Yearbook, thanks to RFJ.

Supplementary file notes

Zaic drawing.


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Flattop (oz13210) by Dave Hewitt 1992 - model pic

  • (oz13210)
    by Dave Hewitt
    from Model Builder
    April 1992 
    38in span
    IC F/F Pylon
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 12/07/2021
    Filesize: 1380KB
    Format: • PDFbitmap
    Credit*: MB2020

Flattop (oz13210) by Dave Hewitt 1992 - pic 003.jpg
Flattop (oz13210) by Dave Hewitt 1992 - pic 004.jpg
Flattop (oz13210) by Dave Hewitt 1992 - pic 005.jpg
Flattop (oz13210) by Dave Hewitt 1992 - pic 006.jpg
Flattop (oz13210) by Dave Hewitt 1992 - pic 007.jpg
Flattop (oz13210) by Dave Hewitt 1992 - pic 008.jpg
Flattop (oz13210) by Dave Hewitt 1992 - pic 009.jpg

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User comments

Hi, I am sending photos [main pic, 003-008] of the Flattop models that we operate successfully in the Czech Republic in Pilsen. Motor MP JET 040 PB
Martin Kresadlo - 11/08/2021
This project is published in Frank Zaic's book (Model aeronautic year Book of 1953 on page 35) with the name: AMA Record A/2 Power.
samit - 23/12/2021
Yes, we have a scan of that as a supplement, thanks to RFJ.
SteveWMD - 23/12/2021
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