Electric -VS- Hydraulic Systems in Warbirds

[VCS1]

I would like to get the opinions of the warbird operators/pilots I have seen contribute to the WIX. As you may be aware I am building a P-35A replica fighter. In doing the systems review, I have a decision to make whether to use the original P-35 electric system or retrofit the P-43 hydraulic system (P-35/P-43 are very similar and share many parts) to my "project" for the primary control of retractable landing gear, brakes and flaps.

I am not a pilot, have not faced an in flight emergency, or had to make split second decision as a PIC. From an operational perspective what do you prefer and what would you consider to be a better contribution to flight safety?

I thank any contributors in advance. This is what makes the WIX such a fantastic resource fro the Warbird community.

-David

[agent86]

My personal preference would be hydraulic systems.its just a pressure source ,fluid and slave.no wires, no motors,no servos just liquid under pressure.the easier/simpler ,the better. and I would avoid pneumatic systems .depending on air pressure is an easy,cheap way to go,but a major pain in the beehind

[Trey Carroll]

Have you considered retro-fitting a T-6 hydraulic system into your plane? You can probably find more parts and support for a T-6 system as opposed to a P-35 or P-43. (not that I'm familiar with the P-35 or P-43 systems)

TC

[Chris]

I agree with Trey. Use off the shelf parts as much as possible. T-6 systems are about as tried and true as you can get.

[VCS1]

Hello and thank you for the suggestions. I actually am using a modified T-6 tail gear trunnion and axle assembly, since the P-35 and T-6 both use a 12.50 tail wheel.

I have been able to source a few Vickers/Pesco parts that are called out for the P-43 hydraulic system. The primary difference between the T-6 and P-35 is the actuation of the tail gear. The T-6 use a hydraulic cylinder to raise/lower the tail gear; the P-43 uses a ball screw arrangement that is driven by a hydraulic motor. Ironically the P-35 setup is almost exactly the same except the drive mechanism is extended by a series of rods and clevises that are hooked to a central electric motor (located about AC center) that drives everything else (main gear/flaps). This setup obviously worked for the P-35 (and the POF AT-12 which is a 2 seat P-35 continues to fly with this original design) however the overall safety factory is what I am concerned about.

In looking at "modern" GA aircraft such as the Beech Bonanza, the electric motor route has also been utilized with success, but most "warbirds" seem to use hydraulic systems. My inquiry was the utilization of these systems in normal/emergency situations and pilot preference. Both electric and hydraulic systems have reduntant back ups to lower gear/flaps in the form of manually operated pumps or hand cranks. I would like to know how effective these really are and what is like to operate them in a emergency situation.

My only experiance is with these type of systems is with the AC jacked up safely in a hanger doing gear swings! Guys like Vlado and other pilots I hope can provide some perspective.

[skymstr02]

The primary difference between the T-6 and P-35 is the actuation of the tail gear. The T-6 use a hydraulic cylinder to raise/lower the tail gear; .

Uh, NO, the T-6 tail wheel is fixed.

[Matt Gunsch]

Electric, less weight, no leaks, easier repairs, fewer parts, no flammable fluids
B-17 and B-29 are mostly electric planes.

[Chris]

I'm not really sure about less weight and fewer parts since you still need jack screws or chain drive systems plus the weight of the motors themselves but the flammable liquid issue is there. In looking at your icon though, a beech C-45 gear and flap system with the motors and chains under the floor with the emergency crank on the same crank right by the pilot seat might work. Pretty simple and lots of old C-45 carcasses around.

[Matt Gunsch]

if you figure in the weight of all the tubing, supports, pumps, lines, tank, accumulator, fittings, fluid, actuators, check and relief valves, it all ads up, not to mention all the room needed to mount the parts and route the tubing, so you have to think of how everything tied into everything else. With electrics, you can almost do each item separately and figure out the wire routing later.