Letters Between Vern Clements and Bob Hall

These are letters between aviation historian and draftsman Vern Clements of Providence, Rhode Island and Bob Hall, designer of the Hall Bulldog, from Hilton Head Plantation, South Carolina. The letters span from 1981 to 1987.

In these letters, Bob answers questions about the design of the Bulldog. At one time there was some controversy among aviation historians about the actual shape of the wings, with some doubting the existence of sweepback. Bob confirms that there is 5 degrees of sweepback, no washout, and “extreme” differential in the ailerons—with no down movement at all. He states the sweepback was necessary to balance the aircraft.

I am in possession of Vern’s original drawings of the Hall Bulldog. After intense analysis we’ve concluded that Vern’s drawings are not as perfect as he hoped, but they are extremely close. Vern fought unfair controversy over his understanding of the Bulldog. Other historians doubted not only him, but Bob Hall’s memory! With the help of modern technology to scan in the photos and perform analysis of the 3D shape, we now know exactly what the Bulldog looked like, and we know that Bob and Vern were of course quite correct.

The Letters

October 28, 1981

In this earliest letter, Vern asks Bob Hall to confirm the 5 degrees of sweepback and what airfoil was used. Bob confirms “Yes” to the sweepback and writes that the airfoil was “NACA M6 thinned down to 75% of its normal thickness.”

February 16, 1987

This is the most detailed letter. Vern asks about washout in the wings, and Bob writes simply “NO.” Bob also provides a fascinating account of the first flight: the ailerons were originally rigged with equal up and down deflection, but when attempting a left bank, the plane rolled to the right—“VERY DISCONCERTING.” They figured out that the down aileron was deflecting the whole wing upward, causing the plane to roll the wrong way. They fixed it by putting extreme differential in the mechanism so that the ailerons had no down motion at all. After that, everything was normal and the ship flew beautifully.

August 13, 1987

In this letter, Vern thanks Bob for his March 27, 1987 response and mentions that Bob “could find no errors” in his drafting-board presentation of the 1932 Springfield Bulldog Racer. Vern mentions that “a couple of longtime Aviation Historians have been writing to me, and doubting the work on my drawing of your BULLDOG.” He asks how Bob arrived at the specified sweepback degrees, and Bob writes: “Simply to balance the airplane.”