EFF stands for Electric Fan Fold. EFF is a technique developed by the RC community to build lightweight electric models using fan fold foam board. I recently adapted this technology to build a 30” span Grumman TBF. Although not intended originally for carrier I realized its potential from the start. It flies beautifully, and will hang even though no attempt has been made to move the lead outs to an extreme aft position. The TBF is made from 3/16” Dollar Store foam board, with some minimal balsa re-enforcing. A carbon fiber arrow shaft runs the length of the fuselage and ties into the motor mount.

I liked it some much I have started a second, this time for carrier use. It is a model of a Boeing B-390, it was just a design study but was intended as a competitor to the Vought Flying Pancake.

Power for both is the same, Tower Pro(TP) 2408-21 for sport, and TP 2409-12 for performance.
B390 Specs
Span 20”
Area 200
Estimated 180w/lb sport, 300w/lb performance
All up weight expected to be about 14oz
Control; all electrical through the lines with U/Tronics, with a Universal handle.

Here is the B-390 apparently I am exceeding the size limit

The B-390 flew today. I used the sport motor and although it was windy I could hang it a bit. With the lead outs forward about like a stunt plane, it gets up to about 40-45 degrees. Normal rotation was used, sorry Paul no reverse props.  It appears to have potential. Attached are some photos. Don’t you just hate electric carrier. It works so well. Future plans are to use it as a test bed. An early change will be to add a Kline-Folgerman (KFm2) airfoil. Oh and some paint too.

Joe,
The rubber bands are to power the wing tip prop which maintains line tension. However I get my rubber from Malaysia.

The pink foam is much stronger than the white. The B-390 has been re-enforced with carbon fiber tubes and plywood it selected areas such as the hook strong point. It should hold up pretty well. On the building board are two pink foam Spitfires, in 15 and 35 profile size.

Deltas are fun but in my experience they don't like to pitch up beyond 45 degrees. Cutting a hole might help, and I am also going to try a KFm airfoil. Right now it is just a flate plate.

Well Joe shamed me into some paint, but don't worry I only used about a oz of waterbase R/C Acrylic. And no, you aren't seeing things. The line on the TBF wing is the KFm joint. Both have been flown mostly with the 130 watt motor. I'll try to get some Hi/Lo times this weekend.

Thanks Doc it is amazing how these simple planes can be made to look good with a little work

When I left this thread a few months ago my light weight concept didn’t look to good. After some thought this winter I came back and have had some success. I made a set of .015X.52’ lines. I use two, not three lines on my electric carrier models, following the AMA protocol for Profile and scale classes, I’ve gone up in line size over a standard 15 carrier.

Working with the B-390 I have been successful flying it on these lines. I haven’t gotten any times yet, and the plane itself does not want to hang very well, but I am getting complete flights and I judge them to be about what a sport 15 would do. More trimming is still needed.

One problem is the motor. The Tower Pro has a very soft shaft and bends easily. They are easy to replace, but it gets tiresome. I will replace it with a Suppo type (BP Hobbies, RC Timer, etc). My goal is to stay under 300 watts which should be reasonably comparable to a sport 15.