Uncle Geoff's Big Tomboy Repair. Again.

[David Davis]

To my eternal shame and embarrassment, being a club level instructor in two countries and the current Coupe Des Barons four-stroke champion, I managed to crash a double sized Tomboy and wipe out the front of the fuselage from the firewall to the trailing edge. It must be the slowest model in my collection but even very slow flying models can stall as I found out when I was bringing it into land last summer. I'd slowed it up too much and with no airflow over the tiny elevator, the model crashed to the ground from a height of about two metres.

I have never had much luck with this model. The plan was drawn up by my Uncle Geoff who taught me how to build model aeroplanes when I was eleven years old so the model has always had a sentimental family attachment. I have built at least four fuselages for the model and managed to crash them all except for Geoff's original which I had to scrap because the balsa had become weak with age. Two of the crashes can be attributed to inexperience but the last one was just dumb thumbs!

If it had been any other model I would have set fire to it long ago but because of the family connections I intend to build the forward part of the fuselage as a sub assembly and to glue it to the rear section. I will make up two formers to in order to increase the glueing area. Picture of Geoff's plan and the rear fuselage below.

My questions are:

1. Do I rebuild the forward fuselage as per the plan and just take greater care of my landings in future? The diagonals are 1/4" x 1/8" and the forward sheeting is 1/8."

2. Do I replace the 1/4" x 1/8" diagonals with 1/4" sq.

3. Do I fill in the foward fuselage structure between the uprights with balsa sheet? If so 1/4" or 1/8?"

4. Should I build the forward fuselage as per plan but introduce a 1mm ply doubler from the firewall to the trailing edge of the wingseat with a bird's mouth extending forward?

Picture of the model in happier times below.

The advice of the cognoscenti is as always keenly sought.

[Chris Walby]

Hi, If it flew alright then I would rebuild it as plan/previous and just give the pilot a stiff talking to about min air speed and landing technique ! ?

 

Can't see the point of changing anything unless you are trying to address problems. 

[J D 8]

      Question with a twice size model is is the structure more than twice as big/strong ? It can be a case of the bigger they are the harder they fall. Can not see a standard Tomboy dropping in from two meters resulting in much if any damage as is the case with my standard Cardinal.

  Some doublers along the wing seat would be good I recon.

  Rather than fill in the frame with sheet, sheeting the fuselage sides and bottom from firewall to rear wing former with I/16 sheet on the outside of the frame would be stronger and lighter. Simpler than filling in and less heavy glue needed.

  Pics are of Cardinal on it's way to a whoopsy [ no damage ] and then floating in to a landing after a better launch.

[Don Fry]

A lifetime of experience tells me;

small models often fly again (if the crashee can be bothered).

big ones create magnificent crash scenes (as in, no starting point)

little engineering differences between big and little have consequences. And if you want twice size, a redesign is a good idea. Not just a bit bigger.

Game of tears. 

Love the photo, the stick twiddler, in exited mode.