Airdrome Airplanes Sopwith Pup Project

snj5 · 8 September 2009, 03:19 PM

Quote:

Originally Posted by RAF56_Ball

Fro all, Tracy O'Brien just sent me a message that Robert Baslee is working with him on the small discs like on his site for the C-90. .

Yes - I asked Tracy to do this last week and he is waiting on the hub drawings from Robert to custom drill the discs for a simple and elegant solution that is supportable. He is very easy to work with, and this hopefully will fill our small plane's humble requirements.

For our plane purposes, we need brakes to:
1. hold in position on startup
2. hold at low power setting for ignition check
3. make a 'suggestive' tap on a wheel brake if rudder is not persuasive enough
4. break for slow pirouette turn if needed

I am struggling as well with activation and rudder bar use. I will wholly agree that the Sands rudder bar with toe brakes is mightily impressive, but I was hoping for something simpler. I have seen Blakes N28 horizontal mounted toe brakes and heard about Rick's N24 firewall mounted master cylinders - both working well by report. My current leaning is to use the Hegar five inch dual master cylinder mounted just behind the rudder bar pivot point, with easily installed extended pedals on the levers.

I am still working on it, but this seems very simple and would elegantly solve the problem.

Thanks for everyone's great input.

hank jarrett · 8 September 2009, 06:04 PM

Glenn,
Stranded steel cable is extremely strong, even in small diameters. I doubt someone could break the cables in a Nieuport by pressing both pedals at the same time (even the small cables). That wasn’t the point. It is STRUCTURAL damage that happens (fairly often in cases of fear induced pedal pressing). When I did crash investigations I saw steel tube control sticks bent 20 and 30 degrees, a throttle ripped from its mount (still in the pilots hand) and rudder pedals broken off (these were not accidents where we got to talk to the pilot). When the adrenalin is pumping hard, your body can apply incredible force and something has to break. Sometimes a bone, but it’s always the weakest link in the load path. Trust me, if you are in a high fear situation you are more than capable of bending the aluminum longerons in the Nieuport. In the Navy, I rarely found brakes damaged by stomping, usually it was the tires blown and gear damaged by going off the runway (or more massive damage if the plane went off the flight deck). A Nieuports structure is more than adequate for normal loads, but this isn’t a normal situation.
I do agree that hitting the brakes that hard on the ground would probably put you on your back (or the tires would just slide, need to do a brake induced pitching moment analysis to tell you when you would stop sliding and start pitching over, but it can be calculated) but we weren’t talking about the brakes, it’s about the rudder cables.
I know for a fact, if you are a normal, healthy, male (and most females, though I don’t have data on women- they weren’t flying jets in the Navy when I did that kind of work) you can bend up a Nieuport with rudder pedals instead of a rudder bar if you are properly motivated.
Look at the load path. Rudder bars dump the load into the cockpit fuselage bar mounts and pedals put the load into the longerons, cables and rudder horns.
I like rudder pedals, like in my Taylorcraft, but to keep the tail light, I’ll use a bar in the Nieuport. My Nieuport will probably have cable brakes, like the “T”, just strong enough to hold for a run-up and a little "encouragement" when the rudder isn't enough on the ground (or that rare occasion when a ground loop is better than a barbed wire fence). I hope to copy Rick's N24 firewall mounted hand brakes you press with your toes. Maybe I can become as good a pilot as Rick if I copy his brakes.

Hank

snj5 · 8 September 2009, 07:36 PM

Quote:

Originally Posted by hank jarrett

I hope to copy Rick's N24 firewall mounted hand brakes you press with your toes.
Hank

I think this idea sounds even better, as you could mount to a fuselage tube on the firewall or whereever.
Any photos out there ?

hank jarrett · 9 September 2009, 05:27 AM

Not a very good picture because of the angle but the anodized handle can be seen attached to the tube on the firewall. Neat set-up using a bike hand brake.
Hank

By the way, take a close look at the workmanship in the other areas of the picture. This is typical work for Rick. Just beautiful, even where you would never see it.

snj5 · 9 September 2009, 08:03 AM

Quote:

Originally Posted by hank jarrett

Not a very good picture because of the angle but the anodized handle can be seen attached to the tube on the firewall. Neat set-up using a bike hand brake.
Hank

By the way, take a close look at the workmanship in the other areas of the picture. This is typical work for Rick. Just beautiful, even where you would never see it.

Many thanks for the photo! I think this solution is brilliant. Matco and Hegar both make hydraulic hand master cylinder units that would mount the same and work with the Tracey OBrien brakes.

Agree on the great workmanship!

Brad · 9 September 2009, 09:39 AM

Quote:

Originally Posted by hank jarrett

Not a very good picture because of the angle but the anodized handle can be seen attached to the tube on the firewall. Neat set-up using a bike hand brake.
Hank

By the way, take a close look at the workmanship in the other areas of the picture. This is typical work for Rick. Just beautiful, even where you would never see it.

Hank,

What I was trying to describe is essentially the same thing, except the handles (pedals) mounted to the rudder bar so you can engage both to stop without any difficulty, and still have differential braking, no matter the position of the rudder bar.

See the little "sketch" attached for the general idea.

hank jarrett · 9 September 2009, 10:49 AM

Cool! Could I make one suggestion? Move the Bowden cables or the hydraulic lines to the center of the rudder bar with LARGE loops (or route them up so they can twist freely) so there isn't any chance of catching one and interfering with rudder movement. Loss of rudder control in a Nieuport could be really bad for your health!
Hank

Brad · 9 September 2009, 11:36 AM

Quote:

Originally Posted by hank jarrett

Cool! Could I make one suggestion? Move the Bowden cables or the hydraulic lines to the center of the rudder bar with LARGE loops (or route them up so they can twist freely) so there isn't any chance of catching one and interfering with rudder movement. Loss of rudder control in a Nieuport could be really bad for your health!
Hank

Hank,

Good idea. (And yes, they're "Bowden cables" i.e. standard bicycle brake cables.) I sketched them on the outside to keep them clear of the other controls... and I indicated that they go back simply for firewall clearance. You could actually run them forward instead, letting the pedal "push" the housing instead of "pulling" the cable end- and if there is enough clearance at the firewall I think that would be preferable.

The idea the way it is drawn is to "u-turn" them back forward running along the longerons, and run them down the front gear legs. I didn't draw the cable "u-turn." I think that would be clear of everything though... the "u-turn" bend would allow fore-and-aft movement of the rudder bar, and I don't think there is anything there for it to hang on- maybe a gusset. I'd have to look at the exact location in the bird.

I personally think Rick's setup is a very cool idea- using actual bicycle brake levers. I'm trying to think up a SIMPLE way to mount those on the rudder bar with the cables pointing in, and the handles where they can be used by your toes without interfering with something... still mulling it over. (It would also be hard to draw in MS Paint... lol )