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The Hybrid Aircraft Flies - A Press Release According to Aviation Week

Aviation Week & Space Technology    Attribution: An Email Originated Article Forwarded to HAC via a Interested Reader; For full article see Aviation Week & Space Technology

 

 

Lockheed Martin's Secretly Built Airship Makes First Flight

By Michael A. Dornheim

02/05/2006 09:06:00 PM

SKUNKS WORKING

Lockheed Martin Advanced Development Projects is making perhaps the first realistic tests of a hybrid airship--a concept that dates back many decades but that is just now being tried at a significant scale.

The Skunk Works had secretly built the craft and hoped for a quiet first flight at its Palmdale, Calif., facility, but a few passers-by noticed the strange object in the sky.

The Defense Dept. is showing interest in two categories of airships--those that can carry large cargo at low altitude, exemplified by the Defense Advanced Research Projects Agency (DARPA) Walrus program, and those that can operate in high-altitude low-wind conditions and remain on station for long periods of time. The configuration of the Skunks Works ship indicates it is the former--a hybrid heavy-load carrier.

The interest is across the services and the notional applications are diverse, ranging from logistics--delivery of an integrated fighting unit within theater, for example--to sensor, communications and even laser-weapon relay platforms.

But airships aren't there yet. Major unresolved issues could derail the airship dream, such as their traditional delicate ground handling, and possibly prohibitive economics and vulnerability. These issues have been debated endlessly on paper, and now Lockheed Martin, a prime airship proponent, is investing to seek real answers.

A hybrid airship derives most of its lift by being filled with a lighter-than-air gas such as helium. Overall, it is heavier than air and gains the final 20% or so of lift by flying like an aircraft, but with slow takeoff and landing speeds that allow operations from short unprepared strips.

The Skunk Works made the first flight of its "P-791" testbed on Jan. 31 at its facility on the Palmdale Air Force Plant 42 airport. The manned flight was about a 5-min. circuit around the airport in the morning and appeared to be successful. The company did not announce or want to discuss the flight.

The P-791 is not part of a government contract, but rather an independent research and development project by the Skunk Works to better understand airship capabilities and technologies, such as materials, a company official says. However, it may also be a quarter-scale prototype of a heavy-lifter.

TO GAIN MORE SPAN TO ACT LIKE a wing, the P-791 is three pressurized lobes joined together. An observer of the first flight says it was about the size of three Fuji blimps blended together. The Fuji blimp, a Skyship 600 model, is 206 ft. long. That suggests the P-791 would have a gross lift of roughly 3-5 tons.

The observer saw the craft performing very tight 360-deg. turns while taxiing. It made a brief takeoff roll, climbed to a low altitude, made a few banks--including a long sweeping turn--then came back and landed. The landing approach had a nose-down body attitude that levelled for the flare. The flight was very smooth, the observer says. The craft was flown by P-791 Chief Test Pilot Eric P. Hansen.

The speed of the testbed was estimated at about 20 kt. A full-scale version would be able to go much faster, over 100 kt. Lockheed Martin has long proposed a large transport airship, at one time called the Aerocraft, which was halted around 2000 (AW&ST Feb. 22, 1999, p. 26). That design was about 800 ft. long and was to carry 1-1.2 million lb. at 125 kt. The Skunk Works was one of two contractors to receive one-year, $3-million Darpa contracts in August 2005 to study Walrus. The second Walrus phase would be a three-year demonstration effort.

Hybrid airships have a long history. The Aereon Corp. in New Jersey started experiments in the late 1950s, but they were small scale (see www.aereoncorp.com). The company tested the "deltoid aerobody" shape, also called a deltoid pumpkinseed, with a 1,200-lb. manned demonstrator in 1970-71. That was followed by several studies funded by the military at less than $1 million. In the U.K., the Advanced Technologies Group built a 40-ft.-long unmanned SkyKitten hybrid airship and flew it in 2000 (AW&ST Sept. 23, 2002, p. 30). Nothing in the field has progressed to the size or apparent sophistication of the Skunk Works testbed.

The P-791 uses four air cushions as landing gear, located on the outer lobes. Taxiing the vehicle could be like flying a hovercraft, except one with greater exposure to winds. An advantage of the air cushions is they could be reversed to suck the aircraft onto the ground to resist winds for cargo operations. Air pressure may also be the best way to spread landing loads into the inflatable structure. It's not clear if there are any devices, such as wheels, to keep the airship from sliding sideways when taxiing in crosswinds. The craft has a special towing system.

GROUND HANDLING IS A MAJOR ISSUE facing hybrid airships. Conventional lighter-than-air craft require large ground crews and, because they are especially sensitive to winds on the ground, the airstrip is an area ripe for accidents. Hybrids are only slightly heavier than air, and a hybrid must show large improvements in ground handling over a standard blimp to be successful. The P-791's current limits are to remain in the hangar if winds are above 5 kt., and there is a 10-kt. limit for taxiing and flight. That could restrict its flight test in windy Palmdale. It's not clear how the pilot was performing the balletic spins on his taxi-out--whether purely with vectored thrust, or by spinning around one sucked-down air cushion, or other means.

The P-791 appears to have four propellers--two at the tail and two on the sides. The tail units appear to be able to pivot for yaw vectoring, and it's unclear if the ones on the sides can move. One knowledgeable individual says there are four vectored propulsors used for ground handling, but it's not clear if these are the main propellers, or separate units perhaps connected with the air cushion system. The rings around the motors may be shrouds for the propellers and/or gimbal rings for vectoring. Vectored thrust can be useful for lighter-than-air blimps, which lose conventional control authority as they approach zero airspeed while landing, but a hybrid airship lands with some airspeed that may keep the tail control surfaces effective. But for control during low-speed air cushion taxiing, vectoring would seem essential.

The P-791 appears similar to the proposed full-scale version of the British SkyKitten, called the SkyCat. They have similar overall shapes--though the Skunk Works design is wider--and similar propulsion layouts, and both use air cushion landing gear. Perhaps the two programs have people in common.

One of the partner names on the side is TCOM, which makes aerostats and envelopes for airships.

"Hybrid airships have been the subject of studies and questions for half a century," one expert says. "Now it stops being hype and they will meet reality."

 

A Press Release by Antelope Valley Press

Skunk Works' new craft over Plant 42

This story appeared in the Antelope Valley Press on Thursday, February 2, 2006.

By ALLISON GATLIN
Valley Press Staff Writer

PALMDALE - A mysterious flying craft seen hovering over Air Force Plant 42 Tuesday morning was the latest creation from Lockheed Martin Aeronautics Co.'s famed Skunk Works on its maiden flight.

The blimp-like aircraft, known simply as P791, is a proof-of-principle vehicle to help engineers learn more about technology and aerodynamics for such airships.

"Lockheed Martin is testing a small-scale airship as part of an internal research and development effort," Lockheed spokeswoman Dianne Knippel said.

The large white airship is shaped somewhat differently from a traditional blimp, with twin torpedo-like sections joined in the center and a cockpit beneath. Four airlifters move the vehicle on the ground and in the air.

The company, known for its advanced technology developments conducted in secrecy, is not releasing any additional information about the project at this time.

The airship likely will be seen flying for the next six weeks, generally during the morning hours, Knippel said.

 

Followed by an unofficial personal account

 

 

 An accounting of the events of first flight Project P-791 on 31 January 2006 at Lockheed Martin SkunkWorks, Palmdale California according to an eyewitness. 

The flight test crew had been briefed the night prior to the event. The winds were forecasted to be around 3 knots which would have been within the "first flight" testing criteria of not greater than 5 knots. The aircraft was declared ready for flight. 

The HAC team gathered at the hangar at approximately 5:45 AM. Some forty or so other folks had already arrived. Food and drink were assembled on multiple tables in the hangar entry befitting the traditional first flight festivities hosted by Lockheed Martin. The area was open to those gathered, an uncommon practice to the typically closed practices of plant security. But this then, was a special day, and it was obvious by the crowd's gathering, suggesting that this event was about to see something quite different from any other. Three luxury busses were waiting to take a VIP crowd to the viewing area to observe events as soon as the hybrid aircraft was to leave the hangar. 

But something was amiss, and potentially disturbing. We felt it as we departed our parked cars and proceeded to the hangar. It was the wind; not three knots, but over ten, and gusting. Someone forgot to tell the weatherman! Once inside the hangar and as the time 6:30 AM approached it was becoming obvious that wind would perturb the scheduled testing events. We anxiously awaited Lockheed Martins declaration.  

First Dr. Bob Boyd made the announcement, then it was followed by a statement that our "Invited Guest" badges might be more valuable on EBAY the following day since the dates would be wrong, as it was the current opinion that the tests would be postponed to a subsequent date.  

As some folks started to depart it was Neil Kacena who announced that they would wait as long as 7:30 AM before cancelling, hoping that the winds would somehow abate and the guests not disappointed. As time advanced the winds continued and became more "gusty" and hopes faded. Then, strangely, at 7:24 AM the winds stopped; not even a breeze. As fast as our hopes had faded, our expectations again soared. 

Suddenly the crews hopped into action, the guests were rushed into the busses, the hybrid was taken into tow out of the hangar and we were all off to the flight line, refreshed by the expectation that within a matter of minutes we would finally see the historical first flight of our hybrid aircraft.

Out onto the flight line, to the north of the same runway where we had a week earlier viewed the ground testing activity, the busses took up position; the guests to the event disembarked and waited anxiously. It was now about 7:40 AM. Big Bertha as I called her (the hybrid aircraft) advanced to a holding area at the end of the runway as the pilots continued their checks ending finally with the ballonet final inspection and a call that they were ready.....; when all of a sudden there was a radio transmission that the control room was down. What do you mean the control room was down? Lets launch this thing...what do you think we are waiting for...its the hybrid that has to get airborne not the control room.  Then there was the obvious explanation, we need the control room to monitor and record the telemeter data from the aircraft from which to ascertain flight qualities and other performance functions. "How long to get it back up?", was the query transmitted from our vantage point. "Fifteen minutes to reload because of a power interruption", was the reply. OK, that's not bad. We will wait. Believe me we would have waited all day. AT 8:00 AM we settled down thinking just a few minutes more and the show would start. AT 8:15 AM another delay of about 10 minutes was announced...a UPS failed and we will have to reload again was the nervous voice on the other end of the radio. Nerve racking, but intent upon seeing this through, the time ticked off and then the call, that was sweet to our ears; We are back up...lets go. 

Finally, the aircraft started to increase power and positioned itself on the end of the runway and not quite stopping, began to advance. Then a real surprise; within two body lengths the long awaited expectation....IT'S AIRBORNE. The sight was just too much to behold. My Goosebumps had Goosebumps and I'll have to confess it was hard to hold back tears at such a marvelous sight. Its been years since I jumped around like an idiot...I usually just walk around that way....but this was the event of a lifetime; of a century; and whatever else one might fathom up.  "Bertha" I love you! 

The aircraft took to an altitude of between three and five hundred feet, passed overhead and into the morning sunlight. The two pilots were obviously having fun because they made a number of airborne maneuvers.

As the pilots neared the end of their outbound leg Big Bertha turned starboard and then to the port and re-approached the runway for the very first historical landing. The aircushion landing system had been extended throughout the flight and as the aircraft passed in front of us the aft hover cushion touched first, fingers fully extended, then the aircraft had sort of a soft, but slight bounce where the forward cushions made ground contact, then the vehicle settled down on all four. The aircraft rolled out, came to a stop, then advanced slowly to the end of the runway. Four minutes had elapsed. Mission accomplished! 

You can only imagine the excitement and the dialogue rendered by all. A non-eventful landing; sweet words to a flight test crew, but as far as events go this was was anything but non-eventful. History will record this event as the start of a new age of affordable cargo transportation that can go anywhere. 

If there were any critics or skeptics in the crowd they became zealots favoring the program that day. I suspect that all of Palmdale heard about the aircraft, as crowds and cars were lined up on Sierra Highway watching the events on the field. Word has it that pictures are already on the internet and an Antelope Valley Press (the local newspaper) reporter called asking if Lockheed Martin cared to make a comment. 

As the guests arrived back into the hangar, Bertha was allowed to travel back to the hangar under her own power and through the fence where she was finally hooked back onto the tow vehicle and pulled back into the hangar. As the pilots disembarked the cockpit, they were greeted with the traditional "water barrel" christening where in lieu of a standard shower, they were treated as though they just went through a car wash. 

Then fun was had by all, speeches, awards and accolades to those who contributed to the enterprise.

From start to finish; from a clear sheet of paper to product, only fourteen months. Lockheed Martin should be proud. Yet another demonstration of engineering brillance and leading edge commitment from the infamous "SkunkWorks".

 

 

 







 
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