C-124C PHASE IV PERFORMANCE AND FLYING QUALITIES

by Fred Stoliker

In spring, 1953, I was assigned as the flight test engineer for the Phase IV performance and flying qualities tests of the C-124C Globemaster II. The project pilot was Captain Wayne W. Eggert, copilot was normally Captain Randy Fetty but others flew in that position, and the flight engineer was Captain Walter W. Whiteside. Nobuo (Bob) Sunada, who was later killed in a B-57 accident, along with Andy Hontz served as an Assistant FTE while working as a summer aide. As was normal for performance tests with piston engines, one engine had extensive instrumentation to measure air pressures around the cylinders and to measure temperatures at the cylinder heads and cylinder bases. On four-engined aircraft, the instrumented engine was the number three engine.

The C-124C resulted from modifications to the C-124A aircraft. The most noticeable external differences were the nose radome for the weather radar and the wing-tip pods containing the heaters for de-icing. Other changes impacting performance and flying qualities were: more powerful (3800 vice 3500) horsepower engines with a manually operated two stage blower; larger diameter, clipped-tip propellers; and changes to the wing flaps and the ailerons. It was still a big aircraft in relation to others flying at that time period. It was still "The Great Aluminum Cloud" and because of the higher power available was even more so "The Douglas Vibrator".

C-124C #52-1004 on static display at the Pima Air & Space Museum at Davis Monthan AFB

Where'd that bird come from?

As a result of all the high power demands on the engines during performance tests, engine replacements were quite common. An uninstrumented engine could be replaced in a matter of several days whereas the replacement of an instrumented engine could take months because of the required instrumentation build-up - and of course, an instrumented engine was never built up until needed because of the costs.

As you can well imagine, we did lose the number three engine and were down for about six weeks. When instrumentation and maintenance crews said the aircraft was ready, we ran a series of ground checks including running all four engines at high power. When all checked out we scheduled a flight with a takeoff gross weight of 175,000 lbs. Shortly after takeoff, the flight engineer announced that we were losing power on number four engine - torque was dropping rapidly, fuel flow was increasing, cylinder temperatures were dropping, and manifold pressures were decreasing. We turned on the camera to get data while we were feathering the propeller. After we raised flaps and gear, we held a quick consultation and decided as long as we were airborne we would conduct three engine tests - and so we did for about eight hours. Then, we alerted maintenance that we had "lost" the number four engine and were returning to base.

Upon landing the maintenance crew prepared to replace the engine. After they swung back the cowl flaps and were disconnecting the air scoop to the carburetor, they found an owl with a four-foot wing span spread over the carburetor inlet. He had very effectively choked off the airflow to the carburetor causing the power loss and the strange readings. After the owl was removed, the crew "buttoned up" the cowl, ran an engine check, and pronounced that the aircraft was ready for flight the next day.

The aircraft flew many more flights but we gave the owl a funeral with full military honors. Then we all sat down to work on a keg of beer.

A big ice cube

The C-124C cargo compartment was filled with water ballast tanks that held 50,000 lbs of water that could be shifted fore and aft to control/change the center of gravity (cg) or dumped overboard in emergencies or to change the weight of the aircraft for specific tests. There was a flowmeter in the lines used for shifting water to control cg but we also had calibrated "dip-sticks" that were used to check ballast tank quantities before and after flights and before and after dumping/transferring any water.

All flights were conducted from Edwards and it was routine to fly tests over the ocean because of the calmer air there. We often flew missions that were six to eight hours in duration where we would take off at 175,000 pounds and then conduct a series of tests while using fuel and dumping/transferring ballast to attain desired conditions. One day we had conducted a series of tests between 15,000 and 30,000 feet. On the way back to Edwards Wayne Eggert had the co-pilot conduct a series of qualitative stability and control tests at 10,000 feet including power-on stalls - and power-on stalls always resulted in heavy buffeting.

C-124C in flight.

After landing we discovered a discrepancy of about 150 gallons of water between our pre-flight and post-flight dip-stick checks. I was quite concerned about the difference and carefully checked the dip-stick values, but couldn't find the discrepancy. Then the crew chief and I got a maintenance stand and started checking all the dump valves. We finally concluded that the aft dump valve had a small leak and the seal needed replacing.

Several days later one of the Douglas engineers brought in a newspaper clipping showing a car dealer in Long Beach, California, standing next to a car that had the whole top crushed in. The dealer was quoted as saying that he was in his office when he heard a load crash. He looked outside but stated that he didn't see or hear any planes or any unusual noises. That evening as he was closing his lot he noticed the damaged car with a puddle of water in the damaged roof.

I called Wayne and told him of the leak and casually mentioned the article about the car. Wayne said that the co-pilot had been flying a stall test over Long Beach at about the time the chunk of ice descended on the car. We speculated that the water from the leak had frozen on the bottom of the aircraft while we were flying at altitude and then had broken free during the stall tests. We agreed that we wouldn't mention our leaky valve to anyone!

Who keeps blowing that horn?

The C-124 had very noisy hydraulic pumps but they normally couldn't be heard in flight because of all the engine noise. The C-124 brakes were supplied from the ship's hydraulic system - and incidentally, there was a pronounced delay between the time the pilot stepped on the brake pedals and braking occurred. However, when the brakes were applied the hydraulic pumps would almost immediately start up with their high-pitched whine. The sequence, as it occurred, was: 1. The pilot stepped on the brake pedals; 2. the hydraulic pumps came on; and then 3. you would feel the braking action start.

After Bob Sunada had made several flights, he asked me at the post-flight brief one day "Why do they blow that horn before they put on the brakes?" We were all puzzled by his question until we thought through the sequence and then explained it to Bob.

We all then had a good laugh - not at Bob but with him. Thereafter, whenever someone new flew with us Bob told the "horn" story on himself.

“Just call me Red”

During that same summer, we had a large number of summer aides working at the Base and it was decided that it would be a good morale booster and recruiting tool to give them a flight in a test aircraft. The powers-that-be authorized the whole lot - approximately 35 aides - to be flown on the C-124C while we performed an airspeed calibration.

We scrounged around and finally came up with enough parachutes to supply everyone and it fell to me explain how to fit them and how to use them. I assembled all the aides and explained how to adjust the chute harness. Then I launched into the need to carefully tighten the crotch straps before bail-out so that you wouldn't lose any vital parts of your anatomy when the chute popped. At that point, I looked up directly into the face of the only female aide. I felt my face go a fierce red color but she politely smiled and said nothing. However, for the remainder of her tour at Edwards she always addressed me as "Red".

Then off we went into the wild blue yonder. Once we had reached test altitude, Bob went back and told them they were free to roam around the cargo compartment and explained that the F-86 pacer aircraft would soon be off our right wing. We then got busy with our test. About half-way through the calibration the pace pilot let out a yell and moved away from us. The C-124 pilot Captain Eggert asked what was wrong. The pacer pilot responded "Every one of your hundreds of windows has got at least one face in it." He soon rejoined us and we finished the test without further incident.