Adam A700 Twin Jet

Following a conservative certification path and with a familiar engine, the A700 may lead the pack in deliveries.

by Rick Durden

For those who have been around the block in aviation a few times, the pronouncements about light jets by the factory PR staffs and popular press have been the source of considerable entertainment. We are, if we believe the hype, about to be eyeball deep in $1 million revolutionary jets.

Weve heard so many claims of technological breakthroughs that will turn the industry on its ear over the years that we want to dope-slap the next marketing dweeb who opens his mouth. Bluntly, aircraft technology is mature, so the changes to come will be evolutionary, which is the way its been since the last big breakthrough, the jet engine, in the late 1930s.

The rules dont and havent changed much. Attempting to certify a radically lighter airframe and unknown avionics matched with an uncertified engine is an exercise in financial hemorrhaging. Sure, once in a millennium, someone pulls it off. But the more likely scenario involves lots of smoke and mirrors and color brochures with fantasy performance figures followed by the slobbering sounds of bankruptcy lawyers feeding on the carcass.

Against this backdrop, we still think that a light jet can be sold at a profit for something on the order of $2.5 million or so and its going to an interesting horserace to see who succeeds at it. One company that appears to have a reasonable chance of success is Adam Aircraft, of Englewood, Colorado. In the January, 2004 issue we reported on the companys A500 piston twin and in this report, well examine the A700 twin jet, set to sell for about $2 million.

Low Key
Adam seems the antithesis of companies long on hype and short on performance. It has been remarkably conservative in its approach to design and certification. While the engine it has chosen has not been certificated (as of this writing), the airplane otherwise uses existing technology throughout. Further, Adam is using the time-tested technique of leveraging the development of a larger, more capable airplane by first certifying a smaller version that is, in itself, over designed and overbuilt.

By using many of the already proven components of the A500 piston twin, the A700 jet has a jump start on the process of complying with FAA Part 23 regulations. Over-designing the A500 drove its certification cost up, but not by much, as the airplane was conventional in all ways and gave the FAA nothing new to dither over.

This approach has been so speedy that Adam stunned Oshkosh show goers last summer by showing up with a flying version of the A700, putting its would-be competitors on notice that weekly press releases announcing the successful subcontract for beverage holders matters less than having a flying airplane.

The A700 flying prototype was made from what is intended to be production tooling. The Williams FJ33 engine which powers it, although not through the certification process, is not a breakthrough engine. Its 80 percent the size of the proven FJ44 and develops roughly two thirds the thrust. While the engine is scaled down, it uses the full-size gearbox from the FJ44, which should ease the certification process and improve reliability.

The engine will develop 1200 pounds of thrust, giving a thrust-to-weight ratio for the A700 of .38, which compares favorably with the Cessna CJ1s .34. Target empty weight is 3700 pounds, which might be doable but we wont be surprised to see a weight gain.

If Adam can hit its weight goals, with full fuel, the airplane should be able to carry 700 pounds in the cabin (three occupants) 1100 miles with NBAA reserves or, with reduced fuel, eight people on a 500-mile trip with reserves.

The FJ33s on the A700 are to be unihanded, a design consideration for charter and fractional operators. Because the engine can be installed on either side of the airplane, the operator wont have to keep handed engines in inventory. Each engine will have two sets of mounts and will have all other connections to the airframe duplicated, one on each side of the engine, as well as dual oil dipsticks. An engineer at Adam told us the philosophy is that if something goes wrong with the engine, it should be easy to swap so the airplane can continue revenue flight while the engine is repaired.

While selecting an uncertificated engine on a new airplane is always a risk, the FJ33 is among the better bets, in our view. Both Williams and Pratt and Whitney have previously downsized established engines successfully, so theres a track record to support the idea. Williams is less likely to encounter showstoppers with a downsized FJ44 than it did with the radically lightweight engine it was originally building for the Eclipse 500, the EJ22 (now the FJ22).

Big Cabin
The Adam 700 is not a tiny airplane; its exterior is roughly the size a Cessna 421. It will seat six if a potty is installed or eight, including crew (single pilot) without. The prototype is 41 feet long, 9.5 feet tall and has a 44-foot wingspan. Gross weight is targeted at 7000 pounds. The cabin will be about the same size as that of a Cessna CJ1 or 90-series King Air. Max cruise is targeted to be 340 knots at 38,000 feet with a max operating altitude of 41,000 feet.

Whats most interesting to us is that the claimed balanced field length for the airplane is only 2950 feet, less than for virtually all piston twins, which will open up a massive number of airports to jet service.

The A700 varies externally from the A500 in having a slightly longer fuselage, a nose baggage area and jet engines astern rather than a piston engine at each end of the fuselage. The tail of the A500 was built oversize, giving a far longer center of gravity range than was needed. This allows commonality of parts with the A700 but also offers the option of stretching the jet airframe later.

Adam engineers found that when the airfoil of the A500 was optimized for its roughly 220-knot cruise speed in the low 20s, the indicated airspeeds involved were the same as for the optimal 340-knot cruise of the A700 in the high 30s. The A700 airframe, save the control surfaces, is composite. The value of composite construction lies not in weight saving, as was once thought, but in cost of manufacture. The conservative FARs with regard to structural strength cause composite aircraft structures to weigh just as much as the same design in aluminum, but the composite structure can be made with fewer parts and is stronger.

In addition, the composite structure can be built by less skilled workers, which Adam is taking advantage of by keeping its manufacturing almost entirely in house, including tooling. Adam found that when development dictates a structural change, it can build the new tool in-house within a week, as opposed to a delay of weeks or months if tooling is out-sourced. Also, by operating around the clock, as is done in the computer world from whence Rick Adam came, three times the amount of work is accomplished per calendar week, without having to pay overtime.

Both approaches may be among the reasons why Adam was the first company to actually fly a personal jet to Oshkosh, rather than make do with a mock-up and a lot of hype. Further, it claims to have burned only $60 million to develop both a piston and a jet aircraft, a fraction of what Eclipse has spent.

The A700s wing leading edges are one piece, allowing easy installation of the TKS deicing system or repair in the event of damage. We were told that testing showed that hail just bounces off a composite airframe without damaging it and the hangar rash that dents an aluminum airframe wont do more than scratch composites. When the A500 suffered a nosegear fold after a test flight, the airframe repair took a total of 19 hours of labor.

Should the impact be severe enough, the modular nature of the A700 will allow the damaged part to be removed and replaced. However, we are hearing reports from the insurance industry that one-piece composite wings havent been a slam-dunk hit for insurers. In the event of serious wing damage. The cost to replace the entire wing is so high that insurers are declaring the aircraft a total loss, something that will need to be watched to see how it affects premiums in the next few years.

The piston A500 has 230 gallons of fuel capacity in the wings, providing more than adequate endurance. Turbine engines, with their higher fuel specifics, mean more fuel has to be carried in the A700 to meet its range goals, nearly 50 percent more. Theres no more space in the wings so Adam told us its planning to follow the example of other jet manufacturers and place a belly pod under the fuselage.

Adam apparently intends to take advantage of what Lockheed discovered with the Constellation and what was again proven with Cessna belly pods: they may look bulky and drag-inducing but they actually extract only a tiny aerodynamic penalty. The A700 belly tank is expected to carry about 100 gallons and will allow the engineers to create what is effectively a single-tank fuel system, where the wing tanks supply the belly tank and the engines draw fuel from it. While weve always had a high level of discomfort with fuel in or near the fuselage from a crashworthiness standpoint, our review of accidents doesnt indicate that belly tanks on jets have increased the incidence post-crash fires.

The A700s landing gear is hydraulic, with redundant lines for a nitrogen blow-down system. It has a wide track, with trailing beam main gear legs. Our observation on flying the A500 was that the gear made for easy directional control and ground handling and the trailing beam made it difficult to determine precisely when the aircraft had left or returned to the ground.

The flight deck of the A700 is among the most comfortable weve tried. It has more than adequate head and legroom and because it uses a sidestick rather than a yoke, its easy to get into and out of the seat. Four-point restraint systems are standard for all seats and the seats meet the most recent FARs for impact, 26Gs forward and 18Gs down.

The prototype had no overhead switches or gauges, something we were pleased to see. When we flew the A500, we found the flight controls, except for the high friction in the ailerons, to be appropriately harmonized with forces that one would expect in an aircraft of this size. When we sat in the A700 prototype, we noticed that the aileron system had much less friction than the A500, thus we anticipate a control feel for the A700 to be close to that of a 400-series Cessna.

The pressurization system is intended to provide an 8000-foot cabin at the max operating altitude of 41,000 feet, with a max differential of 8.33 PSI. The only complaint we have about the flight deck was some restriction to visibility upward, which we noticed while maneuvering in the A500. As the A700 is to be a single-pilot aircraft that will be mixing it up with low-and-slow goers in the pattern, eyebrow windows above the windshield would be a nice addition, in our view. Avionics for the A700 are to be a combination of Garmin and the Avidyne Entegra line, providing a glass cockpit display appropriate to an aircraft of this class.

The target market for the A700 is Part 135 and fractional operators. At a current price of roughly $2 million a copy and the ability to carry as many as seven passengers in single-pilot operation, the A700 may be an eye catcher for the air charter and fractional business.

The mainstream press has been touting the next generation of light jets used for charter as an economical alternative to airline transportation for businesses and reasonably well-to-do larger families. What has been ignored is that theres a certain degree of resistance from the general public to little airplanes. While the A700 is by no means a Boeing BBJ, its tall stance, large OV-10 look-alike tail and decent-sized fuselage may overcome some of that trepidation.

Further, the passengers wont be sardined together as in, for example, the smaller Eclipse 500. Another reason for targeting Part 135 and fractional operators is the insurance market. After three decades of a soft market, the aviation insurance business became unprecedentedly hard in the early 1990s and shows no sign of relaxing. GAs lousy safety record is one reason for this.

While a jet is far easier to fly than a piston-engine airplane, that benefit is more than offset by the increased demands on the crew associated with the speeds and altitudes and at which theyll have to fly, especially when in high density traffic areas. The insurance companies have watched amateur pilots in high-performance airplanes erase themselves and their wealthy passengers for years.

Adam is realistic enough to recognize that insurers arent going to be excited about covering the local multi-tasking multi-millionaire who can now afford himself a jet. Adam reasons that if individuals are willing to undergo the initial and recurrent training, have the discipline to operate a jet and can get insurance, then it will happily sell them an A700 and support them wholeheartedly.

However, it realistically doesnt foresee that sort of person as the primary market for the airplane. Rick Adam says his company is designing the airplane for who needs it rather than who wants it.

We have to say we find that attitude to be a welcome splash of cold water to the face. With Eclipse falling behind schedule and the Safire jet running into money problems, Adams keep-it-simple-and-hold the hype philosophy looks as promising as anything weve seen thus far. Were not ready to declare the A700 the winner of the personal jet sweelstakes but stay tuned.

Also With This Article
“Personal Jets: The Story Up to Now”

-Rick Durden is an attorney, CFII and an Aviation Consumer contributing editor. He lives in Michigan. See for more.