S41a Flivver (oz14733)
About this Plan
S41a Flivver. Free flight model for indoor flying. Wingspan 24 in, wing area 119 sq in. For electric power with DJ Aerotech MPS-1 geared motor. Uses foam construction.
Note this plan is available as a free download from the FlyRC site (see Datafile).
Update 1/10/2023: Added article, thanks to RFJ.
Quote: "Lightweight electric for small spaces. Gryffin Aeroworks S-41a Flivver, by Thayer Syme.
Over the last several months, I have been thinking more and more about designing a new model for indoor and backyard flying. A trip to Toledo and an upcoming article on indoor airfoils by Jef Raskin provided just the sparks I needed to get going. Now that I was committed, what was this plane going to look like?
I've long been a fan of the early English ultralight designs from the 1920s and 30s. Gryffin Aeroworks was not a company of the era, but it sure sounds like it could have been. The S-41a Flivver was clearly inspired by that era and keen observers will likely recognize several influences. Interestingly, full-scale airplanes of this type are regaining popularity, as pilots look for inexpensive quick-building designs to sate their hunger for flight. That sounds awfully familiar.
MATERIALS: With little spare time for the project, a sheet foam structure made the most sense. This model had to be quick to build. I chose Zepron foam from Air Dynamics for the basic building material. Made in the US, Zepron is similar to the Depron foam that is so popular in Europe. Zepron also has a light surface skin, which adds stiffness and ding resistance, and it is a perfect material for 'doodling' with new designs.
Zepron is easily formed using the heat of a covering iron or heat gun. I made a balsa form for the wing and inserted it, along with a wing blank, into the oven. Zepron heat forms at a relatively low temperature, so it may take some experimenting to find a setting that works for you. I would recommend 150 degrees for your first try.
Building the Flivver was almost a non-event. I printed my drawings at full size; then cut parts from Zepron sheets with a new X-acto blade. I had a complete set of parts within five or ten minutes.
Before you glue anything together, make some decisions about markings. I used some art markers to detail the wing and tail 'structure.' I got ahead of myself and mounted the wings before coloring the fuselage. If I get around to it someday, some trim strips of colored tissue will be applied with a glue stick.
I used PK Industries NI1000E foam-safe odorless CA to assemble the fuselage. For final airframe assembly, I used the faintest dabs of PK Industries 30-minute epoxy. Faster epoxy works as well, but I appreciated the extra time for alignment and attaching multiple parts. Whatever you use, go sparingly with the glue. There is no need to add extra weight. Even the smallest amount of glue will be stronger than the foam it is securing.
Make sure that you hinge the elevator before gluing the fin and stab onto the fuselage. It is captured in the fin cutout once the glue cures. I bought some 3M Blenderm adhesive bandage tape for the hinges..."
Supplementary file notes
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
by Thayer Syme
all formers complete :)
got article :)
Found online 30/07/2023 at:
Format: • PDFbitmap
Do you have a photo you'd like to submit for this page? Then email email@example.com
User commentsLooks similar to a Heath or Church Midwing, but I don't think this is a scale model, per se. (Unable to find scale documentation) A very attractive model, nonetheless.
D A - 11/08/2023
Ah, good point. Ok have unset the scale tag on this one now. Thanks.
SteveWMD - 11/08/2023
Add a comment
* 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.
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.
© Outerzone, 2011-2024.
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.