On September 8, 1982, the engineering department at Gulfstream Aerospace Corporation’s Commander Division was released to modify Model 695A serial number 96062 for use as the Model 1200 prototype. This modification was similar to that performed on the Australian Department of Aviation’s five 695As (serial numbers 96063, 96069, 96075, 96078 and 96085) in that it introduced certain redesigned wing structure elements, thus simplifying the modifications that would later be required to recertify them as Model 695B aircraft. Airframe design changes for the Models 695B and 1200 were started at the same time in early 1983 since both models were identical in that respect.
Essentially, the Model 1200 was to be a Model 695B airframe with TPE331-12-701K engines installed. Initial factory paperwork showed the engines were to be TPE331-10G-511Ks, although that engine was not certificated until August 14, 1984, with the TPE331-12-70K being certificated on December 19, 1984.
The TPE331-12 engine had a manufacturer’s continuous power limit of 900 shp. Possibly, its thermodynamic horsepower number was 1200, thus establishing the name given the model. Gulfstream Commander was the first airframe manufacturer to select this particular AiResearch engine. Engineering chose to flat-rate the Model 1200 engines at a nominal 875 shp. Based upon a rudder control system redesign that had to be accomplished in mid-1984, it is evident that 875 shp was all that could be reasonably certified on this airframe. Although big in potential horsepower (and price), the TPE331-12 engine had the same case dimensions as the previous series of TPE331 engines and weighed only about 9 pounds more than the Dash 10 engine. However, increased mass flow through the engine required a larger air inlet area and a slightly larger diameter tail pipe.
Gulfstream’s Preliminary Design Group had recommended the use of a four-blade Hartzell propeller for the Model 1200. Since the propeller disc loading only saw a power increase of 75 shp, this does not appear to have dictated the need for a fourth blade. The fact that the Dowty Rotol propellers, although of exceptional quality, had become very expensive might have prompted the decision to go back to a Hartzell product.
Other non-scientific influences also were being felt. At the prompting of the marketing department, a set of Hartzell four-blade propellers were test-flown on a Model 681 aircraft in 1968. These propellers had a macho look that exuded the feeling of power and, in addition, some competing aircraft brands were using them. However, Gulfstream engineers were able to show, at that time, that they were not as efficient as the three-blade Hartzell propeller being used, so the effort was temporarily dropped. Nonetheless, requests for these four-bladed propellers continued to arise regularly from the sales folks, driven more by looks than logic.
In December 1982 the four-bladed propellers were used on a Model 695A to evaluate the acoustic characteristics. Since the frequency of propeller tip passage increased from about 80 beats per second to slightly more than 100, this meant redesigning the sound attenuation methods in use. Later, for the Model 1200, engineering was planning to go to sound-reduction methods and materials developed by NASA. This was to have increased the weight of the Model 1200 interior by 123 lb.
Records indicate that Gulfstream Commander flew two different configurations of Hartzell four-blade props on s/n 96062. Each four-blade prop weighed about 20 lb. more than the Dowty three-blade unit.
After the Model 695B program was wrapped up in February 1984, engineering continued to work on the Model 1200. This included the flight testing and data preparation for an FAA FAR 135 Pilots Operating Handbook. FAR 135 most commonly relates to air taxi operations but also governs any commercial transportation using aircraft under 12,500 lb. gross weight. This was something that Beech had offered for years but was a new undertaking for Gulfstream.
The most pressing problem encountered was the necessity of maintaining satisfactory (and certifiable) single-engine minimum control speed (Vmc) after the increase in engine power. This required the introduction of “Lock-Clad” type control cable assemblies to minimize rudder system cable stretch and maximize rudder deflection under airloads. The program also included the design of a servo type rudder trim tab system to reduce the rudder pedal forces encountered by the pilot in such situations.
In October 1984, as Chief Engineer-Propjets, Bill McGinnis was requested to give Bill Humes (Division President) and his directors a presentation on the improvements attributed to the Model 1200. This was quickly followed by the Marketing department insisting that such a presentation should compare the Model 1200 with the Model 695A and not the Model 695B. Bill complied with this request but cheated a bit and flagged to a footnote all Model 1200 improvements that had already been introduced on the Model 695B.
The history of the aircraft during its development is as follows:
- September 8, 1982: Decision was made to use Model 695A serial number 96062 as the Model 1200 prototype, with the engines to be used quoted as TPE331-10G-511K, with registration N9982S.
- March 2, 1983: Gulfstream Aerospace Corporation requests the FAA to assign N120GA.
- April 1, 1983: New registration, N120GA, assigned to the aircraft for Gulfstream Aerospace Corporation.
- August 23, 1983: Initial certification was in the Experimental—R&D category. The engines shown were TPE331-10-501K, with Hartzell HC-D4N-5L/LEP569-5 four-blade propellers.
- November 16, 1983: With TT of 21.80 hours, the basis of certification was changed to Experimental—To Show Compliance with FAR.
- April 3, 1984: At TT 49.30 hours, certificate renewed, but now with engines shown as TPE331-12-701K with Hartzell HC-D4N-5L/JD10194B propellers.
- June 4, 1984: At TT 122.20 hours, certificate renewed.
- October 22, 1984: At TT 237.50 hours, certificate renewed, with propellers now shown as Hartzell HC-D4N-5L/JD10185B.
- June 27, 1986: At TT 265.10 hours, certificate renewed, with engines now shown as TPE331-10-511K with Dowty Rotol (c)R306/3-82-F/7 /VP3034 propellers and now shown as converted to a Model 695B.
- July 17, 1986: Certificated in the Standard-Normal category under Revision 42 and Proposed Revision dated June 30, 1986; the aircraft was sold to the State of Virginia, Department of Highways & Transportation, Richmond, Virginia, the same day.
In November 1984, the Model 1200 was pushed aside since engineering was very busy completing flight-testing of the SMA-configured Model 695B for the DEA, the first one of which was scheduled for delivery in mid-January 1985.
At the time the Model 1200 program was terminated, engineering was still experiencing problems in getting the Hartzell four-blade propeller and the Dash 12 engine to operate together in harmony.
Since, at the time, Gulfstream was the only user of the TPE331-12 engine, the cancellation charges incurred on termination of the AiResearch contract were sizeable.
Here is a comparison of the Model 695B and the Model 1200, listing some of more interesting parameters:
| Model 695B | Model 1200 | |
| Ramp Weight (lb.) | 11,800 | 11,800 |
| Take Off Weight (lb.) | 11,750 | 11,750 |
| Standard Empty Weight (lb.) | 7,359 | ** 7,602 |
| Useful Load (lb.) | 4,441 | 4,198 |
| Maneuvering Speed / Va (Kt.) | 158 | 158 |
| Maneuvering Load Factor (g) | 3.80 | 3.80 |
| Max Continuous Speed (Kt.) | 308 at 21,000 ft. | 320 at 20,000 ft. |
| Max Cruise Speed (Kt.) | 297 at 21,000 ft. | 314 at 24,000 ft. |
| Takeoff Over 50 feet at Sea Level (ft) | 2,288 | 2,069 |
| Landing Over 50 feet at Sea Level (ft) | 2,117 | 2,291 |
| Twin Engine Climb Rate at Sea Level (fpm) | 2,630 | 2,989 |
| Twin Engine Service Ceiling with 100 fpm r.o.c. (ft) | 33,900 | 36,000 |
| TPE 331 Engine Series | -10 | -12 |
| Flat Rated Nominal SHP | 800 | 875 |
| Propeller Description | Dowty-Rotol | Hartzell |
| 3 blades | 4 blades | |
| 106″ dia | 102″ dia |
** = This weight included several features that were optional on the Model 695B but made standard on the Model 1200.
Following the sale of the aircraft to the State of Virginia, it was immediately re-registered as N2VA. On March 26, 1987 an Experimental-To Show Compliance category certificate was issued, with TT at 277.20 hours, in order to test the installation of a camera and navigation sight. They were then signed off as being installed in accordance with STC No. SA3765SW on April 24, 1987 and certification was returned to Standard-Normal category.
Having been re-registered again, now as N12VA, in May 2007, it was sold, possibly as a trade-in, to Hawker Beechcraft Corp in July 2007. It was eventually sold in February 2010 to Airborne Research LLC., Fort Pierce, Florida, who are the current owners.
Author’s note: Credit is due to Bill McGinnis for supplying much of the information for this article.
Barry Collman’s lifelong interest in airplanes began when he was growing up in a house located underneath the downwind leg to busy Northolt aerodrome, an R.A.F. base near London-Heathrow airport. As a young teenager he discovered airplane “spotting”–hobbyists’ observation and logging of aircraft by make, model, and registration number. The hobby began to grow into a passion as Collman joined a club of like-minded spotters. At one point he purchased a copy of the January 1966 U.S. Civil Aircraft Register, and thumbing through it came upon the Aero Commander. He was hooked. Eventually he acquired every available FAA microfiche file on Commanders, and since 1995 has made annual pilgrimages to Oklahoma City to sift through FAA records. He now has a database with about 100,000 records as well as a collection of negatives, slides, photographs, digital images, magazines, brochures, knick-knacks–and a very understanding wife. This series on Commander production history originally was written for the Twin Commander Flight Group, of which he is an enthusiastic member.
