Doc, I originally joined RCU to help someone else with a Whopper, but unable to find the thread.

I've also heard of the "string" method to hold the Whopper back while gaining rotor speed, but have not tried due to safety aspects. I prefer to have a clean/dry O-ring in the head drive and a 10-15 mph headwind. The only reason the tail feathers get damaged is due to a hard touch down on landing due to rotor blade flex, or a take-off rollover causing the rotor blades to swing back in their blade holders.

As to airworthiness; do you know the flight history of this Whopper, How does it look to you. If you are not familiar with helicopter rotor heads, or to be more specific, the Robbe/Schluter System 88 rotor head, I suggest you find someone who does. If not, I would look at and call ... http://www.ronlund.com/ ... as I'm sure they can be of help. The most important items to check and confirm are the main shaft, blade cross shaft/spindle shaft, control rods, ball links and flybar. The rotor head rotates clockwise and the rotor blades and flybar paddles should reflect this.

The original Whopper was supplied with wide under cambered rotor blades and latter replaced with a narrower/longer Clark-Y airfoil. I'm hoping you have the Clark-Y as it was a vast improvement in performance. Rotor blade appearance can say a lot about the Whopper's history.

The Whopper head speed has been Sky-Tached at 800rpm and has the visual appearance of a solid disc ... if you can see rotor blades you haven't got sufficient head speed.

This is only a start. I can supply you with copies of the original instructions and reduced size assembly drawings if you'd like.

David