0790

Item 0790

DESIGN: SynchroLite ~ Rotor - Disk - Autorotation

Under development - For the fun of it - As time allows

Outside Helicopter

UltraSport 254

Tip weight: 2 pounds.

T/K formula is 2.5 seconds.

SynchroLite

FORM: Flight - Autorotation

For this form to be run the following forms must have been previously opened and run.

	[Helicopter] ~ Open at desired helicopter.
	[Momentum} ~ Open & Run
	[Flight - Hovering] ~ Open.
	[Test Conditions] ~ Run.
	[Flight - Hovering] ~ Run.
	[Element Data] ~ Open & Run.
	[Rotor - Hub] ~ Open & Run coning angle.

Notes:

Rotor Speed Decay: [tKE]

The time from power failure to zero RPM. Note this is theoretical and based on hovering with maximum power and 30 HP engines. In reality this power setting will result in vertical climb of forward flight. The actual time should be just about twice as long.

Comparative figure used by Sikorsky. ACCESS database autorotation_index()

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To eventually, and maybe, provide;

Amount of rotor decay between power failure and pilot reaction.
What is the minimum steady rate of descent.
etc.

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Pitch-Cone Coupling:

First of all, pitch-cone coupling in the stable direction (i.e. pitch link is located at trailing edge of the blade; which the SynchroLite has) extends the time for transitioning into autorotation in the event of engine failure. As the rotor slows and cones up, pitch is automatically reduced; with pitch-cone ratios of 2:1 or more, the pilot need not touch the collective if engine failure occurs in level flight where not a lot of collective is pulled in. [Source CA Beaty]

Rotor Governor:

The use of a rotor governor will assure that the rpm of the rotor can never drop below a specific value, unless the pilot overrides it.

The Bell 206 has a disk loading of 3.66 lbs/sq-ft. and a descent rate of 30 ft/sec.

The UltraSport 254 has a disk loading of 1.52 lbs/sq-ft. and a descent rate of 15 ft/sec. It is also claimed that the Ultrasport has enough inertia to autorotate to the ground then lift off and re-land.

The SynchroLite has a disk loading of 1.62 lbs/ft., which should give it a descent rate of 16 ft/sec.

With a wide and shock-absorbing undercarriage, the SynchroLite will be hypothetically able to autorotate to a landing, without any intervention by the pilot. This raises the possibility of only providing the pilot with cyclic control, or possibly the pilot is only able to gain collective control after the craft is fully into autorotation. In other word ~ stopping the pilot from panicking and pulling collective at the wrong time.

Related Pages at This Sites:

DESIGN: UniCopter ~ Rotor Disk - Autorotation

DESIGN: Dragonfly ~ Rotor Disk - Autorotation

OTHER: Aerodynamic - General - Autorotation

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SynchroLite ~ Control - Flight - Governor

Last Revised: Sunday, August 10, 2008