The Old Navigator Remembers

Operation "Dual Exhaust"

by Phil Rowe
"Let me get this straight .. " Al exclaimed. "You say we can expect a sudden pitch DOWN when we release the fuel pod?" He emphasized down with an inflection clearly showing concern.

"And we'll be at two hundred feet doing 600 knots, right?"

The contractor's engineer nodded, while putting another slide on the overhead projector. Matter of factly, he continued the briefing.

"Yes, you'll make your third pass over the Edwards range from east to west, passing just north of haystack hill and do your drop before reaching the dry lake."

For 30 minutes more, the crews listened to details of the planned bomb drops over the test range. This would be the first time any B-58 ever released all six stores, hung externally from their sleek supersonic delta-wing bomber.

The B-58 carried four more bombs under its wings, in addition to the centerline weapon. That would make five nuclear bombs, a four hundred percent increase in mission capability.

The single centerline bomb was really two parts, a bomb pod mated to a lower fuel pod. In theory, the crew would release the fuel pod when emptied and continue towards their target with reduced drag and a lighter airplane.

The added small weapons were mounted, one forward of the other, in pairs on either side of the centerline pod. The test drops would demonstrate the factory-recommended drop sequence to keep center-of- gravity changes within limits and also to verify wind tunnel tests which predicted safe clearance for all drops. Released weapons were not expected to hit the wing or the fuselage.

The plan required the crew to fly to the drop zone, first at medium altitude of about 10,000 feet to release one of the small weapons. Then they would descend to 200 feet and drop a second small weapon at high speed, Mach 0.98. Both of these were the aft-mounted bombs.

Then on the third pass, also at low altitude and high speed, the fuel pod would be separated from the centerline bomb. This was expected to be the most hazardous part of the mission because the fuel pod was hinged at its aft end and the forward end would drop first. The engineers predicted that the airplane would pitch down suddenly before the fuel pod cleared, a prospect which clearly concerned the flight crew.

"Then you'll hit your tanker before the high altitude supersonic drops," the briefer added, explaining that the last three drops would be made at 45,000 feet and at Mach 2.0 ( over 1100 miles per hour ), also from east to west. The impact area for all drops would be a few miles east of the Muroc dry lake.

Information sheets described special radio procedures and a listing of data to be recorded during the flight. The airplane would be tracked from the ground with a high-precision radar and several optical devices. This was a key test, with a great deal of data to be collected for later analysis.

Al, the pilot and aircraft commander, turned to his fellow crew members saying, "Sure looks like we've got our work cut out for us."

"That's the understatement of the day," Phil added, as he stood up and stuffed his notes and the handouts into his briefcase. Phil, the Defensive Systems Operator( DSO ) on the three-man crew, was primarily the flight engineer. Walt, the radar navigator, joined them as they left the briefing room, pausing long enough to pick up some aerial photos of the drop zone for later study.

The crew walked out into the brilliant desert sunshine towards the flight line snack bar in the next building, just as an F-4 jet fighter roared low past the control tower. Within seconds another whizzed past.

"Looks like those guys in the test pilot school are getting their jollies this morning," Phil commented, shielding his eyes while looking up to watch them go by.

"Bet they couldn't do that with five externals under them," Walt added. After a quick coffee it was time to fly home.

The next day the crew was back at their home base. They spent the remainder of the week in detailed mission planning for the upcoming tests. Walt carefully plotted the flight's route on the aeronautical charts, using several different scaled charts for selected parts of the flight. The target area required the largest scale chart with the most detail.

A practice was scheduled before the real drop mission. The crew would fly from Indiana to California's Mojave Desert target area, make simulated bomb drop passes and then return to their Indiana base. The mission would be nine hours long and include three aerial refuelings. This was a complex and challenging mission.

Al and Phil drew their flight charts, following the details of the route Walt plotted. Each wrote reminder notes of what they would be doing at various way-points, refueling areas, the climb and descent points and other routine elements typical of any B-58 mission.

Then they got down to the fine details of fuel management, center of gravity (CG) predictions, and even calculating elevon position before and after each scheduled drop. On the delta- winged B-58, the combined ailerons and elevators were called elevons, controlling both roll and pitch. For each condition of gross weight, center-of-gravity and airspeed there would be an anticipated elevon angle. An instrument dial in the cockpits of the pilot and DSO displayed elevon position.

This was an important parameter because if other indicators of fuel distribution and CG failed ( as they often did in B-58's ) the crew could interpret elevon position as an indicator of where the CG and fuel were.

On airplanes with such a wide range of speeds and altitudes, the control of CG and fuel distribution throughout the flight is critical. If the CG is allowed to move too far aft the airplane becomes unstable, too far forward the elevons rise to compensate and cause excessive fuel-consuming drag.

Al and Phil reviewed the complete flight plan, minute-by-minute for the test portion and especially the fuel and CG changes.

"The CG shift with that fuel pod drop won't be much, Al," Phil explained. "By the time we get ready to drop it won't be more than an empty shell, probably won't even notice the weight loss. But I can't say that I'm looking forward to a sudden pitch down."

Al agreed adding, "Yeah .. I'll probably put in some extra nose up trim and just hold her level with forward stick force just before the release. That'll give us a little margin if the pitch down is a bear."

"Any complications about the targets, Walt?" Al asked as he turned to look over his navigator's aerial photo's.

"Nope. It's pretty easy, really," Walt replied. "With the dry lake ahead and the radar reflectors to track on, it won't be a problem."

They went over Walt's predictions for the release and aiming points and the timing for each leg into and out of the target area. Phil looked over their shoulders briefly, but then went back to his own calculations.

The practice flight would be a little different from the real one of course. After all, they wouldn't be making any drops, just following the route and flight profile. But it would be a chance to get the feel for the real thing, especially the high-speed low-altitude portions.

It was the 17th of May 1963 when they flew the practice mission. Things went pretty much as expected, except for one factor. Phil's carefully calculated minute-by-minute values for the elevon position and fuel distribution were meaningless. It was so rough and turbulent, flying at 200 feet and 600 knots over the target area, that he couldn't even read his instrument gauges. They were just a blur during that washboard-like ride. Neither he nor Al had anticipated it to be that rough.

Four days later they climbed aboard aircraft number 61-2053 for the real thing. Mixed feelings gripped them. They knew that flying the route and finding the target would be easy, the practice mission had confirmed that. But, they still didn't know how the airplane would react to the fuel pod drop.

In their detailed flight planning for the actual drop mission, Phil and Al agreed that it would be a waste of time to calculate precisely the elevon position readings. They elected to concen- trate on the CG and fuel shifts and let it go at that.

The first drop, the medium altitude release at 15,000 feet and 540 knots, was a piece of cake. They hardly felt it when the 1500 pound dummy bomb fell away. And the first low-altitude high-speed run was easy too. That second little weapon let go almost unnoticed in the cockpit, but the turbulence was just as bad as on the practice ride.

The it was time for the fuel pod drop. They came around from the east and once again accelerated to Mach 0.98 and eased down to 200 feet above the desert floor. Walt tracked the target on his radar scope and began timing his approach to the release point.

Al moved his thumb on the trim button of his control stick and eased in quite a bit of nose up trim. To keep the airplane level he had to push forward on the stick to compensate for the trim load. Phil double-checked the CG and fuel state, making sure that the fuel pod was empty before the drop. It was.

Walt counted down the last few seconds before fuel pod release, just as he'd done for the other drops. "Three, two, one .. Release," he calmly declared.

Al toggled the pod release switch and stiffened for the expected pitch down. The pod was away, and nothing unusual happened. Nothing except the slight jump in the CG indicator needle, reflecting the loss of 2,000 pounds of weight, and a slight cracking sound which didn't seem important.

Al released his forward pressure on the control stick and the airplane zoomed upward three thousand feet in just seconds, as the kinetic energy of flying at 600 knots was converted into extra altitude.

"Hey, that wasn't bad at all," Phil declared over the intercom, a clear tone of relief in his voice.

"Wonder what that crack or slapping sound was?" Al replied, "Did you guys feel it too?"

But before the crew could respond, Walt gave Al the heading to fly to meet the tanker. They'd have to gas up again before the supersonic bomb runs. Finally he added "Dunno .. didn't seem like much back here and my instruments don't show anything out of the ordinary."

Phil wasn't listening very intently to the others talk. He was busy calculating the fuel needs and assessing where it would have to go when they connected with the tanker aircraft. Rendezvous would be in 15 minutes.

Refueling was routine. They took on about 60,000 pounds from the tanker and were topped-off in just 12 minutes. Next would be the climb to supersonic flight. They'd accelerate to 600 knots and then climb to Mach 2.0 and level off at 45,000 feet. The route would take them about 200 miles east of the Edwards range for lineup on the target.

Al and Phil discussed the fuel configuration for the approach to the target. Allowance would have to be made for the aft shift of CG with release of the 7500-pound centerline weapon. They decided to add one or two percent of forward fuel transfer before the drop. That would give them a safety cushion and extra margin in case they had to suddenly decelerate and descent after the drop.

Once again Walt counted down the last few seconds before weapon release. "Lookin' good," he murmured as the seconds dwindled away. "Four, three, two, one ... Release."

The bomb fell away and this time the crew knew for sure that they had dropped a load. Within just a second or two the B-58 zoomed up to almost 50,000 feet. It was like riding a roller coaster.

"Whooooeee," Al excitedly announced on the intercom. "How'd ya like that?"

Phil agreed, but was too preoccupied with checking the CG and verifying the gauge's readings. With the drop, the CG had instantly shifted aft about five percent, still within limits but the biggest sudden shift he'd ever seen. "Okay, Al, it's just about what we guessed," he announced.

"Let's stay on aft tank feed until after the next two drops," Al mumbled in agreement while turning to the new heading that Walt had given him. They headed back to the IP( initial point ) for the fifth release.

Releases five and six, the last two small weapons, went like clockwork. Now their sleek airplane was clean, clean meaning with no external pods or weapons attached at all. That bird flew like a fighter now. It was light, clean and fast.

"I'll bet those F-4 jocks couldn't touch us now," Phil couldn't resist saying to Al.

"Yep, we'd leave 'em in our dust," Al responded, just as Walt called out the new heading. Once again they'd have to meet a tanker for fuel enough to get home. The crew relaxed a bit now and settled in for the last refueling and the long ride back to Indiana.

Al really enjoyed the flight home. That wonderful airplane flew like a dream in its now-clean configuration. It was like driving a top-of-the-line sports car. All performance and nimble handling.

After landing at home base the crew made their usual postflight walk-around check of the airplane and discovered the cause of that sudden crack or loud snapping sound coinciding with the fuel pod release.

It had been the rubber seal between the fuel pod and the bomb pod, for there was a 30-inch long, narrow gash in the fuselage, just aft of the pod area. At separation the seal slapped against the plane and like a bullwhip creased the skin of the airplane. Otherwise, things look normal.

It had been quite an adventure and a great relief. The anticipated violent pitch-down had not occurred. The tests went smoothly. It was a successful mission, if not routine. It's known in the official records as the "Dual Exhaust" mission.