QH-50 DASH

infobox Aircraft
name = QH-50 DASH

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caption = A QH-50 on board the destroyer USS "Allen M. Sumner" (DD-692) during a deployment to Vietnam between April and June 1967.
type = ASW drone
national origin = United States
manufacturer = Gyrodyne Company of America
first flight =
introduction =
retired =
status =
primary user = United States Navy
more users = Japanese Maritime Self-Defense Force
produced =
number built =
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developed from =
variants with their own articles =

The Gyrodyne QH-50 DASH (Drone Anti-Submarine Helicopter) was a small, drone helicopter built by Gyrodyne Company of America for use as a long-range anti-submarine weapon on ships that would otherwise be too small to operate a full-sized helicopter. It remained in production until 1969. Several are still used today for various land-based roles.

Design and development

DASH was a major part of the United States Navy's Fleet Rehabilitation and Modernization (FRAM) program of the late 1950s. FRAM was started because the Soviet Union was building submarines faster than the US could build anti-submarine frigates. Instead of building frigates, the FRAM upgrade series allowed the U.S. to rapidly catch up by converting older ships that were otherwise less useful in modern naval combat. The Navy was able to inexpensively upgrade the sonar on World War II-era destroyers, but needed a stand-off weapon to attack out to the edge of the sonar's range. The old destroyers had little room for add-ons like a full flight deck. The original DASH concept was a light drone helicopter that could release a nuclear depth charge or torpedoes. The aircraft was considered expendable.

The manned Gyrodyne XRON Rotorcycle program of the mid-1950s provided prototype work for the DASH, and ultimately the Rotorcycle was modified to produce the initial drone version, the DSN-1/QH-50A The DSN-1 was powered by a Porsche YO-95-6 72 hp piston engine and carried one Mark 46 homing torpedo. The next developmental version was the DSN-2/QH-50B that was powered by two Porsche YO-95-6 engines and also carried one Mk 43 homing torpedo. Serial production of the DASH began with the third version, the DSN-3/QH-50C, in which a 255 hp Boeing T50-4 turboshaft engine replaced the piston engine and the payload was increased to two Mk 44 torpedoes. Three hundred and seventy eight QH-50C were produced before production ended in January 1966.

Operations

DASH's control scheme had two controllers, one on the flight deck, and another in the combat information center. The flight-deck controller would handle take-off and landing. The controller in the Combat Information Center (CIC) would fly DASH to the target's location and release weapons using semiautomated controls and radar. The CIC controller could not see the aircraft or its altitude and occasionally lost operational control or situational awareness. Late in the program, there were successful experiments to add a television camera to the drone.

A tethered landing system was partially developed to land and take off in up to Force-6 seas, but this was never deployed because submarines (the targets) could not launch missiles in hurricanes.

DASH came about because Gyrodyne had worked with the United States Marine Corps to develop a small, experimental co-axial helicopter for a scouting platform. A co-axial helicopter mounts two "main rotors" spinning in opposite directions to control torque, unlike the more common main rotor/tail rotor found on most helicopters. Co-axial rotors put more power into lift, and permit shorter rotor blades. Both traits help a helicopter to be as small as possible. On the downside, the blades must be kept very far from each other in order to avoid colliding, since the blades travel up and down as they rotate. This leads to increased complexity and decreased maneuverability.

For a drone, these tradeoffs were fine. For the DASH role, the original Marine version was modified with the addition of a turboshaft engine for improved performance, and the replacement of the seats and controls with a remote-control system and storage for two Mk.44 torpedoes. In this form the DASH could be flown up to 22 miles from the ship, giving an incoming submarine no warning that it was actually under attack, at least until the torpedo hit the water.

Since it was expendable, DASH used off-the-shelf industrial electronics with no back-ups. the controls were multi-channel analog FM. Over 80% of operational aircraft losses were traced to single-point failures of the electronics. 10% of losses were from pilot errors, and only 10% of losses were from engine or air-frame failures.

The DASH program was canceled in 1969. Although low reliability was the official reason, the manufacturer pointed to the expenses of the Vietnam war, and the lack of any need for an antisubmarine capability in that war.

Modified DASH vehicles continued to operate for several more years in the Vietnam war. With attached television cameras, they were used as remote artillery spotters and organic reconnaissance by their ships.

As of 2006, a small number of DASH drones were still in operation at White Sands test range, where they are used to tow targets and calibrate radars and electronic systems.

The Japanese Maritime Self-Defense Force operated a fleet of 20 QH-50 drones, for use on their Takatsuki and Minegumo class destroyers. With the difficulty of maintaining DASH operations after the termination of the US programme, the drones and associated equipment were removed from JMSDF service in 1977.

Variants

;DSN-1:U.S. Navy designation for nine pre-production aircraft, redesignated QH-50A in 1962.;DSN-2:U.S. Navy designation for three pre-production aircraft, redesignated QH-50B in 1962.;DSN-3:U.S. Navy designation for 373 production aircraft, redesignated QH-50C in 1962.;QH-50A:DSN-1 redesignated in 1962, nine pre-production aircraft for evaluation, with a 72hp (54 kW) Porsche flat-four piston engine.;QH-50B:DSN-2 redesignated in 1962, three pre-production aircraft powered by two 86 hp (64.5 kW) Porsche flat-four piston engines. ;QH-50C:DSN-3 redesignated in 1962, production aircraft powered by a 300 shp (225 kW) Boeing T50-8A turboshaft engine, 373 built.;QH-50D:production aircraft with a larger 365 shp Boeing T50-12 turboshaft engine, fibreglass rotor blades and increased fuel capacity, 377 built.

Operators

;JPN
* Japan Maritime Self-Defense Force;USA
* United States Navy

pecifications (QH-50C)

aircraft specifications
plane or copter?=plane
jet or prop?=prop
ref=
crew=
capacity=
payload main=
payload alt=
length main= 12 ft 11 in
length alt= 3.9 m
span main=
span alt=
height main= 9 ft 8 in
height alt= 3 m
area main=
area alt=
airfoil=
empty weight main= 1,172 lb
empty weight alt= 537 kg
loaded weight main= 2,181 lb
loaded weight alt= 991 kg
useful load main=
useful load alt=
max takeoff weight main= 2,303 lb
max takeoff weight alt= 1,046 kg
more general=

engine (prop)= Boeing T50-8A
type of prop=turboshaft
number of props=1
power main= 255 hp
power alt= 168 kW
power original=

max speed main= 80 kt
max speed alt= 92 mph / 148 km/h
cruise speed main=
cruise speed alt=
stall speed main=
stall speed alt=
never exceed speed main=
never exceed speed alt=
range main= 71 nm
range alt= 82 mi / 132 km
ceiling main= 16,200 ft
ceiling alt= 4,939 m
climb rate main= 475 ft/min
climb rate alt= 145 m/min
loading main=
loading alt=
thrust/weight=
power/mass main=
power/mass alt=
more performance=
armament=
avionics=

ee also

aircontent
related=

similar aircraft=
* MQ-8 Fire Scout

sequence=

lists=
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References

External links

* [http://www.designation-systems.net/dusrm/app4/qh-50.html Gyrodyne DSN/QH-50 DASH]
* [http://www.gyrodynehelicopters.com/ Gyrodyne Heliocopter History]
* [http://www.gyrodynehelicopters.com/jmsdf_destroyers.htm QH-50 in Japanese Service]