I thought I'd go ahead and start my build log for my contest entry. Here is some basic info:

Cessna Skymaster 337/O2

In late 1966 the U.S. Air Force selected a military variant of the Cessna Model 337 Super Skymaster, designated the O-2, to supplement the O-1 Bird Dog forward air controller (FAC) aircraft then operating in Southeast Asia. Distinguished by twin tail booms and tandem-mounted engines, it featured a tractor-pusher propeller arrangement. Having twin engines enabled the O-2 to absorb more ground fire and still return safely, endearing it to its crews. The O-2 first flew in January 1967, and production deliveries began in March. Production ended in June 1970 after Cessna had built 532 O-2s for the USAF.

Cessna produced two series -- the O-2A and the O-2B. The O-2A carried wing pylons for rockets, flares and other light ordnance. In the FAC role, the O-2A identified and marked enemy targets with smoke rockets, coordinated air strikes and reported target damage. The O-2B operated as a psychological warfare aircraft equipped with loudspeakers and leaflet dispensers. It carried no ordnance.

General characteristics
· Crew: 1
· Capacity: 5 passengers
· Length: 29 ft 9 in (9.07 m)
· Wingspan: 38 ft 0 in (11.58 m)
· Height: 9 ft 4 in (2.84 m)
· Wing area: 201 ft² (18.7 m²)
· Empty weight: 2,655 lb (1,204 kg)
· Max takeoff weight: 4,400 lb (2,000 kg)
· Powerplant: 2× Continental IO-360-C piston engines, 210 hp (160 kW) each

Info supplied by the Air Force Museum. Here's a pic of what I'm trying to achieve. Bob

The plane will have a ws of 46.5", will be 35" long and hopefullly weigh in between 30-35 oz. Primary construction is monobloc for the main pod and a KFm3 airfoil for the wing. Primary construction material is depron 9mm for the wings and stereo scraps for the monobloc. As per Tony65x55's original concept, the monobloc will be the central structure. An interesting variance will be the fact that the wing center section will carry the servos for ailerons, flaps, rudder and elevator and receiver. The twin tail booms will be permanently attached to the wing.The two motors (2410-12D's, two 20A esc's, 2250 20c lipo and a nose gear servo will be contained in the main pod. One screw will hold the wing section to the pod for ease of assembly.

Original drawings were from a three view. Being a totally useless nerd when it comes to making cad type plans I am extremely thankful to Tony 65x55 for agreeing to draw workable plans for those who might like to duplicate the project. This is something I absolutely could not do on my own at this point, so thank you Tony for helping me out.

The wing/tailbooms is the biggest challenge. The booms are built around .210 od CF tubes. Rudder cables run inside the CF tubes and Elevator cables run outside the tubes (Sullivan Very Flexible Tubing). Booms will be attached to the main wing with epoxy. Here are a few pics of the initial efforts.

Nice Bob! It's always a pleasure to watch your super quality builds.

Tony

Originally Posted by Tony65x55

Nice Bob! It's always a pleasure to watch your super quality builds.

Tony

Thanks Tony... I can't wait for you to see the Pod. It is truly the "Mother of all Monoblocs". Thanks again for your help on the plans. Bob

The Skymaster's "Pod" is going to be 4.5" wide and 20" long. Since four of the five servos will be in the wing center section there is plenty of room in the pod for a few passengers

The Monobloc is four pieces of 7/8" foam (Insulfoam from Lowes) which is not my favorite to work with but it does have a thin plastic covering on each side which is easy to peel off. A layer of 2mm depron foam will form the outer shell and contain the side windows and details.

I love hanger flying, as it keeps me motivated. Here are some pics. Bob

Bob,

Your plane is coming along great, I really like the construction method & have read references to it in various posts. If you don't mind, could you let me know where I could find more reading material on Tony's monobloc theory (the master monobloc thread), Thank you & good luck in the contest!

JP

Originally Posted by JMPaccassi

Bob,

Your plane is coming along great, I really like the construction method & have read references to it in various posts. If you don't mind, could you let me know where I could find more reading material on Tony's monobloc theory (the master monobloc thread), Thank you & good luck in the contest!

JP

Thanks JP... The master monobloc thread is actually a thread on the Blu-Baby trainer. There are over 3000 posts in this thread so you can find anything there. The basic idea is the monobloc carry's the aerodynamic loads via the wing attachment, accounts for alignment, is simple, fast to build, and incrediblely tough. Simply put... if you cut your monobloc square and attach the fuse sides properly, your plane will fly. Most of the problems of alignment and trim other than balance are eliminated. Repairs are a piece of cake.

Here is the link to the BluBaby thread:

http://www.rcgroups.com/forums/showthread.php?t=681556

Bob

Got some more work done on the Pod of the 337. I used DOW 1" Insulfoam from Lowes for the Pod construction. This type of foam is very soft and hard to work with in terms of avoiding dents and dings, so I decided to go ahead and put a hard finish on it before going any further.

First I put a light coat of acrylic paint over the foam and then filled in most of the dents and digs with Dap "Fast N Final" light weight spackling. I then lightly sanded everything and stretched a pair Wifey's blown out panty hose over the pod and cowling and spread a thin coat of Titebond III glue over the panty hose. After drying overnight, I sanded things with 320 wet dry paper.

The results are pretty good and resulted in a nice hard surface that should handle a nice finish and hanger rash well.

Subscribed. I have a Hobby Lobby 377 that might get "panty-hosed".

Originally Posted by warhead_71

Subscribed. I have a Hobby Lobby 377 that might get "panty-hosed".

Welcome aboard Warhead.....

How does your 377 work without rudders? I was thinking of leaving them off to save a little tail end weight. Thanks in advance for the info. Bob

I haven't flown mine yet, but I'm subscribed to the H-L Skymaster thread and everyone who has flown it says the rudders are entirely useless in the air, and the steerable nosewheel takes care of ground handling. I'll be removing the servo and fixing my rudders with toothpicks and PU glue. It seems that most twin-boom planes gain little benefit from rudders, and fly fine with only ailerons and elevator... for example most P-38 models (GWS, E-flite, Nitro, FlyingStyro) have no rudder control. Not sure why...

oops - double-posted

Originally Posted by warhead_71

I haven't flown mine yet, but I'm subscribed to the H-L Skymaster thread and everyone who has flown it says the rudders are entirely useless in the air, and the steerable nosewheel takes care of ground handling. I'll be removing the servo and fixing my rudders with toothpicks and PU glue. It seems that most twin-boom planes gain little benefit from rudders, and fly fine with only ailerons and elevator... for example most P-38 models (GWS, E-flite, Nitro, FlyingStyro) have no rudder control. Not sure why...

Thanks Warhead... I think I'll leave them off for now. All the plumbing is there so I can add them later if needed. Where is the H-L Skymaster thread located? Thanks again. Bob

Hobby Lobby Skymaster thread

Originally Posted by warhead_71

Hobby Lobby Skymaster thread

Thanks... Warhead