The RCM Basic Bipe is an old favorite of mine. I have found that it flies extremely well with the OS 40 FP, or the OS FS40 Surpass. The original plan has a lot of weird and unnecessary features, so I made my own version that is a lot more light and simple. For an overview of my modifications, keep reading. For complete building instructions, go to Kit Instructions on the main menu or click here.
Here is a photo of a Basic Bipe built by Calvin Brooks from my kit. Nice building, Calvin!
The biggest difference is the top wing pylon. The original plan shows the top wing bolted to a platform on top of the pylon. My version has the top wing pinned through a pair of tabs that sandwich the pylon, so the platform is eliminated. 1/8″ wire and wheel collars are used for the pins.
Here is a photo of the wing pylon showing the holes for the wing pins. (You may notice that I added some balsa strips as a guide for attaching the top fuselage sheeting as well.)
Here is a photo showing the tabs that protrude from the bottom of the top wing.
To keep the top wing from rocking, an interplane strut consisting of a single 2-56 pushrod is placed on each side. These rods are attached to the same type of tabs, placed farther outboard on the top of the bottom wing and the bottom of the top wing. Here’s a photo of the strut attachment tab on the bottom wing.
Here’s a photo of the assembled wings, plus the outboard strut to keep everything rigid.
I also have replaced the chin hatch with a single piece of 1/8″ plywood from the leading edge of the wing all the way to the firewall. The landing gear is bolted onto this plate. I have trimmed a considerable amount from the bottom of the firewall, which increases the slant on the chin block. Also, the bottom line of the aft fuselage is modified, which completely eliminates the fairing that the plan shows on the center section of the bottom wing. Although the modified version looks like the original, it is a lot more sleek, and it weighs less. Here are some photos of the modified fuselage.
The only other major changes are in the inside of the nose section. I’ll supply a lite ply doubler for the tank compartment, and you build this part just like any other plane with triangle stock around the firewall and on either side to reinforce the floor.
Here are some more photos of the plane ready for radio installation and then flying. You can see the landing gear bolted to the bottom of the chin plate, and the outer struts that hold the top wing rigid.
Here are some photos showing my modifications to the bottom of the plane, as well as the finished pylon. I did the pylon finish with a black Sharpie marker, then 6 minute epoxy with a few drops of alcohol for easier spreading. As you can see in the next photo, there is no fairing on the bottom wing center section. It sure is easier to build and to cover this way.