Independent_Root

UniCopter ~ Control - Flight - Independent Root & Tip (IRAT)

Working notes:

September 16, 2004

Changes have been made to the linkages to improve the pitch setting at all azimuths and flight settings. They are still not perfect but they are closer to the desired. It does appear that this relatively simple flight control system will work.

There will be some fun trying to align the lines.

August 25, 2004

Idea: Put an operational flight control system, from cyclic & collective sticks on through to each blade, into the Unicopter mockup. Insert stub blades which give a force that resists the twisting of the blades. This will be used to test the forces required to overcome twisting the blades, and if the forces in one rotor counter those in the other?

~ alternatively ~

Assume certain increasing values of torque for increasing angles of twist. Perhaps assume a nominal construction twist in all blades. Then develop a form in Access to show the results of all permutations of azimuth and flight conditions. See FORM: Flight Controls for UniCopter

Overview of Concept:

Information on the blade concepts for this flight control Rotor Concept - Independent Root & Tip (IRAT)

For the prototype blade that is being developed to works with this flight-control see; UniCopter ~ Rotor - Blade - NACA 00xx

Both the root and the tip controls have a single 1P harmonic.

2P harmonics could be contemplated in the future by using one or two swishrings.

Ideally, it would be best to have electrical rotary actuators in the blade roots, for root and for tip control.

The intent is to incorporate Reverse Velocity Utilization into the UniCopter's rotors.

FORM:

Control - Flight ~ UniCopter; in Access database

Yaw:

Yaw [Pedal] has been incorporated as Opposed Longitudinal Cyclic, only; at this point in time. Yaw consists in having the thrust increase and decrease at 30 deg and 150 deg azimuths. These angles may not be the exact best but they should be close. For additional Information see; DESIGN: UniCopter ~ Control - Flight - Directional

Programming Overview;

Access coding procedures are to represent the act of the actual physical components.

Every time an input is changed the change is accepted then all is regurgitated.
If the craft has no forward velocity and the collective is raised then the root pitches are required to increase more than the tip pitches, particularly the advancing root pitch. The root-pitch horns have a longer arm than the tip-pitch horns. This means that the root-swashplate must be lowered more than the tip-swashplate.
As the forward velocity increases, pitch will be removed from the root pitches. More pitch will be removed from the retreating roots than from the advancing roots.

May want to combine this form with Lateral Dissymmetry ~ UniCopter Form or Tangential Velocity Form.

Blade Pitch Settings:

This section has to do with 1P root and 1P tip control. A separate one is required for 2P root & 1P tip. A seperate one would/will be required for electric actuator because their frequency should be much higher.

Sikorsky ABC: Note that the Sikorsky ABC does not have Independent Root & Tip Control.

UniCopter: - Blade Pitch Approximations and Azimuth, under Different Flight Conditions:

Fast Forward: (150 kts)
Azimuth:	Pitch at Root: ⁽⁴⁾	Variation in root:	Pitch at .75 R: ⁽³⁾	Pitch at Tip:	Twist: θ_1A
0º ⁽³⁾	+0.0º		+8.1º	+10.8º	+10.8º
90º	+3.9º	\|\|	+3.4º	+3.2º	-0.7º
180º ⁽³⁾	+0.0º	7.8º ⁽⁸⁾	-3.3º	-4.4º	-4.4º
270º	-3.9º ⁽²⁾	\|\|	+1.4º	+3.2º	+7.1º

Above: Collective = +5, Twist (avg) = -12, Cyclic = -7, Velocity = 150 kts

Climb - Vertical: (maximum)
Azimuth:	Pitch at Root: ⁽⁴⁾	Variation in root:	Pitch at .75 R: ⁽³⁾	Pitch at Tip:	Twist: θ_1A
0º ⁽³⁾	+14.6º		+9.7º	+8.1º	-6.5º
90º ⁽⁷⁾	+28.4º	\|\|	+13.1º	+8.1º	-20.3º
180º ⁽³⁾	+14.6º	+9.1º ⁽⁹⁾	+9.7º	+8.1º	-6.5º
270º	+0.8º	\|\|	+6.3º	+8.1º	+7.3º

Above: Collective = +16.6, Twist (avg) = -12, Thrust = 1413 lbs, HP = 118

Hover:
Azimuth:	Pitch at Root: ⁽⁴⁾	Variation in root:	Pitch at .75 R: ⁽³⁾	Pitch at Tip:	Twist: θ_1A
0º ⁽³⁾	+17.1º		+9.7º	+7.2º	-9.9º
90º	+29.4º	\|\|	+12.7º	+7.2º ⁽⁷⁾	-22.2º ⁽⁶⁾
180º ⁽³⁾	+17.1º	+6.8º ⁽⁹⁾	+9.7º	+7.2º	--9.9º
270º ⁽⁵⁾	+4.8º	\|\|	+6.6º	+7.2º	+2.4º

Access Hover & Above: Collective = +15.25, Twist (avg) = -12, Thrust = 1145 lbs

Autorotation: (Vertical)
Azimuth:	Pitch at Root:	Variation in root:	Pitch at .75 R: ⁽³⁾	Pitch at Tip:	Twist: θ_1A
0º ⁽³⁾	-1º		+0.5º	+1.1º	+2.1º
90º	-1º	\|\|	+0.5º	+1.1º	+2.1º
180º ⁽³⁾	-1º	+0º	+0.5º	+1.1º	+2.1º
270º	-1º	\|\|	+0.5º	+1.1º	+2.1º

___________

High Speed Climb with Left Lateral Cyclic: ⁽⁴⁾
	Port:					Starboard:
Azimuth:	Pitch at Root:	Variation in Root:	Pitch at .75 R: ⁽³⁾	Pitch at Tip:	Twist: θ_1A	Pitch at Root: ⁽⁴⁾	Variation in Root:	Pitch at .75 R: ⁽³⁾	Pitch at Tip:	Twist: θ_1A
0º ⁽³⁾	+8.8º		+11.4º	+12.2º	+3.4º	+8.8º		+11.4º	+12.2º	+3.4º
90º	+17.5º	\|\|	+17.5º	+17.5º	0º	+17.5º	\|\|	+12.8º	+11.2º	-6.3º
180º ⁽³⁾	+8.8º	+12.6º	+1.5º	-0.9º	-9.7º	+8.8º	+12.6º	+2.5º	-0.9º	-9.7º
270º	+0.1º	\|\|	+8.4º	+15º	+11.1º	+0.1º	\|\|	0.1º	+0.1º	0º

Above: Collective = 11, Longitudinal cyclic = -6, Lateral cyclic (5º down on left and 5º up on right), Fw velocity is 100 mph.

What forces are there on the cyclic stick??

(1)The above red values are the result of the root and tip pitch settings. They represent the blade's mean pitch.

Note: If the Root pitch setting were to represent the value at the location of the widest chord (approximately 0.35 R) then the inserted root value (collective) will play a larger role in the blades 'average' pitch, and this should be better.

Note: The tip pitch activates the blade at r/R = 0.9. It is not at the very tip. Can the torque tube be extended out closer to the tip?

(2) The root of the retreating blade is operating in reverse airflow. By giving it a slight negative pitch it will provide lift, plus the negative pitch will allow for greater airflow to the upper region of the propeller. In addition, the reversed profile drag will provide some rotational torque.

(3) The pitch at .75R will be closer to that of the tip then the 1/4 to 3/4 ratio of the distances to the root and the tip. This is because the tip will twist more for a given torque than the stronger root will.

(4) The root pitch at azimuths 0º and 180º are always equal to each other. This is probably not optimal.

(4) The collective is 11, The longitudinal cyclic is -6. The lateral cyclic (5º down on left and 5º up on right). The forward velocity is 100 mph.

(5) During hover the propeller will not be providing thrust, therefore the flow or restriction of air to it is inconsequential.

(6) It looks like the maximum active twist, NOT INCLUDING CYCLIC, is -22.2º to +10.8º, a total of 33º. It looks like the maximum total twist by using today's high-performance induced-strain actuators will be about 14º

(7) The maximum negative difference between root and tip, NOT INCLUDING CYCLIC, might be -10º. ???

(8) Set by air speed.

(9) Set by collective and rotor governor.

The bold blue values are Maximum positive and negative blade twists. The greatest positive twist is at azimuth 270º and the greatest negative twist is at 90º. The forgoing does not including cyclic movement. For the inclusion of cyclic movement, see the following table.

The extreme root pitches will be approximately +25º to -10º therefor re the profile at the root, the pitch axis should be < 50% of chord but >25% of chord.

From the above tables, it appears that the blades should be constructed with a built-in mean twist of -5º. Then

Working Page:

DESIGN:

B437

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Sub-Pages:

DESIGN:

	Name	Item
	UniCopter ~ Control - Flight - Independent Root & Tip - Overview	1363
	UniCopter ~ Control - Flight - Independent Root & Tip - Blade Root	1364
	UniCopter ~ Control - Flight - Independent Root & Tip - Blade Tip	1365
	UniCopter ~ Control - Flight - Independent Root & Tip - Autorotation Yaw Control	1310
	~~ Reference
	UniCopter ~ Pusher Prop - General - Pusher Prop Assist ~ Control - Flight	1079

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	Name	Item

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Initially displayed approximately: April 17, 2003~ Last Revised: August 22, 2007

The above utility invention is openly and publicly disclosed on the Internet to negate an entity from patenting it, to the exclusion of all others whom may wish to use it. ~ Reference patent law 35 U.S.C. 102 A person shall be entitled to a patent unless - (a) the invention was known ... by others in this country, ..., before the invention thereof by the applicant for patent.