Boeing YQM-94A Compass Cope


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4 May 2008
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Hi All,

i searched the forum and could not find a single mention of the Boeing tender for Compass Cope (NOT the Ryan one). In particular, i wanted to know if anyone has a picture/drawing of the proposed twin engine version.
One of the prototypes, powered by a single J97 turbojet, hangs from the ceiling of the AirForce museum in the X-planes hangar.
nice pictures, I have been researching Compass Cope for a while and never saw those :)

I read on an old Flight international that Boeing was condidering re-engining with two JT15s or Garrett ATF3, and I was wondering what that would look like...they would have probably pushed the engines back and spread them on either side of the fuselage, bizjet like.

But there is also the possibility of pairing them on a dorsal fairing, which, as unlikely as it seems, would be an interesting solution. I would be curious to see how you could pull that one out, if it's even possible. I don't recall any other aircraft having a twin turbofan dorsal installation...or is there? ???
Thanks for the link sferrin!
Orionblamblam said:
The Big Box Of Awesome inlcuded two fairly decent Compass Cope drawings... a detailed three-view and an inboard profile.

wow, this box of awesome is like the arch of the covenant or something...I bow to its powers! :)
Hi folks,
here some info and 3 snapshots from the article "Der Compass Cope-Vorschlag von Boeing".
This article was published on page 42 in the German magazine "Interavia Germany", January 1975.

The engine pylon over the main fuselage was designed to carry one or two engines.
Following engines were studied:
  • Garrett AiResearch TFE731 (favorite)
  • Avco Lycoming ATF3
  • SNECMA Larzac
  • UACL (Pratt & Whitney Canada) JT15D-4
Boeing held talks with West German government about a manned version of the Boeing Compass Cope.
A drawing shows the modified fuselage with a cockpit and a new designed tail.


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Just posted by Periscope Film, flight test footage of the Boeing YQM-94 B-Gull Compass Cope submission ("Compass Cope B"), including the first prototype's crash (and destruction) at the conclusion of its second flight on August 4, 1973. By the way, what is that serving as the chase aircraft? It looks like a modified Schweizer SA 2-37 variant with a turboprop engine and tricycle landing gear (starting at the 2min 13sec mark). EDIT: Looks like the chase plane is the manned version of the E-Systems XQM-93A (GQM-93) "Compass Dwell" competitor (see: ; ).

...interesting flaps / speedbrakes


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Video description:

This silent film from August 4, 1973 shows the second flight of Boeing's prototype "Compass Cope" drone, which unfortunately ended in disaster when the aircraft made a hard landing (read more below including the cause of the accident). The Boeing YQM-94 B-Gull (also called Compass Cope B) was a developmental aerial reconnaissance drone developed by Boeing. It could take off and land from a runway like a manned aircraft, and operate at high altitudes for up to 24 hours to perform aerial surveillance, communications relay, or atmospheric sampling.

Compass Cope was a program initiated by the United States Air Force (USAF) in 1971 to develop an upgraded reconnaissance drone that could take off and land from a runway like a manned aircraft, and operate at high altitudes for up to 24 hours to perform surveillance, communications relay, or atmospheric sampling. Two aircraft, the Boeing YQM-94 Compass Cope B, and the Ryan Aeronautical YQM-98A Compass Cope R participated in the program.

The Boeing YQM-94A is a cantilever shoulder-wing monoplane, basically a jet-powered sailplane, with long straight wings, a twin fin tail, retractable tricycle landing gear, and a turbojet housed in a pod on its back. The engine was a General Electric YJ97-GE-100 providing 5,270 lb (2,390 kg) thrust. The YQM-94A was constructed using aluminium and fiberglass. The lower half of the circular-section fuselage was glass-fibre honeycomb, the same material used for radomes. The wings of the YQM-94A were constructed of aluminium-skinned honeycomb with a fiberglass core which insulated the fuel tanks from the cold encountered at the altitudes it was flown.

Since the YQM-94A was a demonstrator, it used some off-the-shelf components to reduce costs. The datalink was based on the AN/TPW-2A X-band radar. The flight control system was derived from a system developed by the Sperry Corporation for the Beechcraft QU-22B Pave Eagle. The Compass Cope B was controlled remotely from the ground with no autonomous guidance capability. A television camera in the nose allowed it to be remotely flown by a ground-based pilot. The undercarriage for the YQN-94B came from a Rockwell Commander. The YQM-94's fuselage sits lower than the Rockwell Commander, so Boeing used this as a lift-dumping system. As the aircraft settled down on its specially strengthened nose wheel, the wing was placed in a negative angle of attack.

The remote control system was tested using a Cessna 172 aircraft over a ten-month period. Initial flight of the first YQM-94A demonstrator (seen in this film) was on 28 July 1973, at Edwards Air Force Base. This aircraft crashed on its second flight on 4 August 1973. The prototype was lost because a damaged piece of mylar insulation caused an electrical short-circuit in a rudder accelerometer. The erroneous signals generated by this accelerometer caused random rudder movements. This problem was compounded by an erroneous airspeed indication for the ground pilot and a control problem because the left wing was heavier than it should have been. These problems resulted in a hard landing which caused irreparable damage to the first prototype.

The second demonstrator performed its first flight on 2 November 1974, and completed the evaluation program. Later tests of this aircraft included a successful endurance flight of 17 hours 24 minutes at altitudes of more than 55,000 feet (16,800 m). This aircraft was retired to the National Museum of the United States Air Force in September 1979.

Ryan's entry into the competition was an updated variant of the Model 154 / AQM-91 Firefly, which it called the Model 235. Initial flight of the first Compass Cope R demonstrator was in August 1974. However, the Boeing Compass Cope B won the competition in August 1976 on the basis of lower cost, with the company awarded a contract to build preproduction prototypes of the YQM-94B operational UAV. Since the evaluation of the Compass Cope prototypes had shown the Ryan YQM-98 to be superior to the Boeing YQM-94A in some respects, Ryan challenged the award. It did no good, since the entire Compass Cope program was cancelled in July 1977, apparently because of difficulties in developing sensor payloads for the aircraft.

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I recently purchased a box of factory models at an estate. This model appears to be the prototype two engine Compass Cope drone. Model wingspan 15” Length 7”
Hey Jeff - cool. You should be able to attach a picture. We can probably help identify any models you aren't clear on.

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