By Jeremy MacDonald, EAA 748627
This piece originally ran in the August 2026 issue of EAA Sport Aviation magazine.
Here’s the story of how I converted my Mustang II to retractable landing gear, after already having been flown for 750 hours since its first flight in 2000. This is the first time that anyone has retrofitted retractable gear into a Mustang II that is already flying. In my case, the job was all done using keyhole surgery, and everything had to fit and work right the first time or the aircraft would be ruined.
The main gear struts were designed and built by John Thompson 40 years ago. He was the brilliant designer of the main legs for several other Mustang RGs and was a seasoned designer of struts for motorcycles. I had no other parts for the job — just a pair of main gear struts. So whatever I was going to do regarding retracting and emergency extension was going to have to be designed from scratch, and I was also going to have to design and build my own nose gear leg.
I thought a great deal about actuators — and whether they would be electric, pneumatic or hydraulic. I decided that hydraulic is the only way to go because they can exert great power, they can be locked by simple valves, and the rams can weigh very little, if well chosen for the job.
For hydraulic power I used the convertible top pump for a 1994-1998 Ford Mustang. The nose gear is retracted by a main hydraulic ram from that same convertible. The two main gear actuators are each a trunk lid actuator for the 1961-1963 Lincoln Continental convertible. All three are fat and powerful rams. All the hydraulic lines are simply 1/4-inch steel brake line.
This hydraulic system has several major advantages over other retract systems, including simplicity: There are no mechanical uplocks or downlocks needed; instead, dual-pilot check valves, one across each actuator, hydraulically lock each cylinder wherever it stops. Once up, it stays up; once down it stays down. All the above is also accomplished using a low system pressure — capped at 320 psi — and that means little chance of leaks.
Gear retraction is accomplished by a flip of a single switch, which starts the pump and brings up the legs, one at a time. Mechanical sequence valves flip over at preset hydraulic pressures to direct the hydraulic fluid to each actuator in turn. First to come up is the nose leg, then the left main leg, and finally the right main leg.
The pump stops automatically when all three wheels are stowed in their bays. The system pressure then drops to zero, leaving each leg hydraulically locked in position. Gear up takes 18 seconds; gear down takes 11 seconds.
No electrical power, no hand pump, no hydraulic pressure is required to drop the gear in an emergency. Instead, three small valves are opened manually by the pilot, and the main gear legs then each drop using gravity, assisted by a 60-pound gas strut. The nose leg is pushed down by a 130-pound gas strut that has been proven to put the nose leg down and locked at 130 mph. Emergency down takes 22 seconds.
The gear system is entirely independent from the aircraft’s electrical power. It’s all powered by a 20AH lithium iron phosphate battery, weighing 2.4 pounds. Testing has shown that, fully charged, it will cycle the gear at least 20 times. It is charged separately, on the ground, in about 30 minutes.
About 20 years ago, several well-meaning friends advised me to leave the Mustang as a taildragger, not to convert to tricycle. I hesitated but converted it anyway and flew it for 650 hours that way. Well, I’ve finally decided they were right, so now this Mustang has a tail wheel again. There’s just one thing — that tail wheel is on the end of the nose leg! It’s the Alaskan Bushwheels 10-inch fork for a Cessna 185, with a custom-machined bearing housing, mated to an oleo strut. All the leg and fork angles were carefully set up to prevent any shimmy, and that fork was also chosen because it has several built-in clutch plates that, once tightened, prevent the castering wheel assembly from flopping to one side during retraction. That fork is also well proven — it’s installed on thousands of bushplanes.
The total weight increase was only 12 pounds more than the original weight before I began the project, including fluid. Weight and balance was unaffected, which I certainly didn’t expect.
There’s no noticeable change whatsoever in feel or handling since the conversion. The only difference I notice is how much quieter the cockpit is and the sudden rushing wind noise and drag when the gear starts down and its doors open up. I had thought that I might experience some yawing effect as each main gear leg comes down in turn, but I feel none.
My top speed didn’t change because I have a fixed-pitch wood prop, and at 2500 rpm on my O-290D, I’m flying at about 165 mph. What changed, though, was fuel consumption and climb rate. My fuel consumption dropped from 6.8 gph to 6.2 at economy cruise at 2350 rpm and 147 mph, and from 7.8 gph to 7.2 gph at 2500 rpm and 165 mph. The big surprise was the sustained climb rate, which increased from 1,000 fpm to 1,400 fpm at 100 mph. That was entirely unexpected, and I wasn’t looking for a climb improvement, so a 40 percent improvement is really stunning.
The Mustang II is a such a sleek little machine anyway, but when there are no gear legs hanging out there, it becomes a really slippery little flyer. Was it worth all my efforts? Absolutely!
Attention — Aircraft Builders and Restorers
We would love to share your story with your fellow EAA members in the pages of EAA Sport Aviation magazine, even if it’s a project that’s been completed for a while. Readers consistently rate the “What Our Members Are Building/Restoring” section of the magazine as one of their favorites, so don’t miss the chance to show off your handiwork and inspire your peers to start or complete projects of their own. Learn more ->