Fabrication Continues on Bulldog Controls

bulldog7

Despite a lack of updates here on the website, work continues progressing on the Bulldog. It’s been a busy summer with a handful of airshows and other airplanes that need attention, but the one constant here in the maintenance hangar is constant progress on the Hall Springfield Bulldog.

One of the tricky parts for Jim, is that there aren’t any actual plans for the Bulldog. As we’ve discussed before, much of the fabrication has to be figured out from either a handful of old photos (some from newspapers that unfortunately weren’t taken with the idea that somebody would be using them to reconstruct this air racer some 80 years later), or from Jim’s decades of experience and the stories and help he’s been able to collect about how airplanes were built back in the early 1930s.

bulldog6

The rudder pedals are a great example of using experience and history in an effort to create something that is as close as possible to what might have been on the original. It’s probably no surprise that there are no pictures from deep inside the cockpit showing the rudder pedals. And there are no drawings of them either.

Jim decided he would start with some Waco rudder pedals as the beginning of the design for the Bulldog’s pedals. There will be an update with a nod to safety and some modern technology. The original pedals were cable operated, the new ones will have a master cylinder which will be underneath the floor to operate some somewhat more modern brakes.

bulldog1

A lot of the recent work on the Bulldog has revolved around the tail. The horizontal trim system is another place where the only good information we have is seeing that there is a gap around the leading edge of the horizontal stabilizer, so there must have been a trim system that moved the leading edge of the stabilizer. Pretty basic, but that’s about all we know about the trim system.

The frame for the trim actuator is complete, but work continues on the ratchet in the cockpit that will be used to control the adjustment.

On the original horizontal tail, there was a single tube for both the front and rear spar. Jim has opted for a slightly thicker spar both front and rear, but it tapers down towards the tips of the stabilizer with smaller and smaller tubes for greater strength overall. When he first started the project (quite a few years ago), Jim planned on using a similar horizontal stabilizer to what is found on the GeeBee R-2 which would have been skinned in plywood. But it didn’t look right, so we’re going with the setup seen in the pictures above.

bulldog3

Next on the history mystery fabrication plan is fabricating the push-pull rods that connect the stick to the elevator. Air racers of the era were notorious in pitch and getting the controls correct wasn’t always simple or safe. Most pilots of the era were used to long throws with the control stick, but the actual movement of the elevator on the air racers was relatively small.

On both the GeeBee R-1 and R-2 a long control stick was used, but only half as much throw was translated to the actual controls because between the stick and the elevator the distance was effectively geared down through a series of push-pull rods. And that’s going to be the tricky part. Getting the proper amount of control stick throw and the proper movement of the control surfaces while maintaining the correct amount of control sensitivity and forces for the pilot.

The wing attach fittings have also been installed, making it at least possible to get the wings attached. The wings however are for another day…

bulldog5

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *