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Item 0002

OTHER: Miscellaneous - Thoughtless Ideas - Root Turbofan Rotor

September 11, 2008 ~ look into the possibility of only 2 blades and many outlets.

Description of Operation:

During hover outlets 2, 3 and 4 deliver equal thrust. Outlet 1 delivers no thrust.

During cruse outlets 2, 3 and 4 only deliver thrust when they are on the advancing side. In other words, the thrust of these three outlets pushes the craft forward as well as rotating the rotor. Outlet 1 delivers the thrust that is no longer being delivered on the retreating side. Unlike the tip jet, no thrust is generated that is in opposition to the craft's direction of flight.

Sketch:

Overview:

The blades, which are outside of the thrust outlets, are basically conventional blades.

The thrust is high volume - low velocity.

A turbofan engine (possible - Ultrahigh bypass turbofan engine ~ see diagram below) produces a thrust.

This thrust is controlled so that it can be selectively directed to the four outlets. Alternatively, a centrifugal gas turbine.

Outlet 1 is located on the fuselage. Its thrust line will probably have to pass through the fuselage's center of drag.

Outlets 2, 3, and 4 (& 5) are located at the roots of the three (or four) rotor blades. The thrust for these outlets is directed from the engine up the hub and out to the roots of the blades.

Could this be mounted vertically at center of rotor, since lift is required for both hover and forward flight?

Would it be better if the turbofan was radial? The fan could consist of many layers with the upper one being axial flow and the lower ones transitioning to radial flow at the bottom.

Model: Consider utilizing an electric motor to drive the fan in lieu of the turbine.

Description of Operation:

Hover:

The full thrust exits equally from outlets 2, 3, and 4 (& 5). There is no thrust from outlet 1.

Forward flight:

Outlet 1 (on the fuselage) provides the majority of the thrust. The balance of the thrust exits from outlet on the blades when they are located between 0º azimuth and 180º azimuth.
In other words, the three (or four) outlets in the rotor only provide thrust when they are on the advancing side.
When the outlets are on the retreating side, they provide no thrust. However, they will be in zero airflow at medium forward speeds and therefore present no drag, or they will be in reverse airflow at higher speeds and the drag on these outlets will assist with the rotation of the relatively slow turning rotor.

Force Vectors:

The 3-blade rotor appears to be better than the 4-blade rotor.

Re 3-blade Rotor:

Conclusion: It looks like a 3-blade rotor will work.

Blade 1:				Blade 2:				Combined:
Azimuth:	Force:	Forward:	Sideward:	Azimuth:	Force:	Forward:	Sideward:	Forward:	Sideward:
210º	0.00	0.00	0.00	90º	1.00	+1.00	0.00	+1.00	0.00
195º	0.28			75º	1.04
180º	0.58	0.00	-0.58	60º	1.15	+1.00	+0.58	+1.00	0.00
165º	0.85	+0.22	-0.82	45º	1.15	+0.81	0.81	+1.03	-0.01
150º	0.58	+0.50	-0.29	30º	0.58	+0.50	+0.29	+1.00	0.00
135º	1.15	+0.81	-0.81	15º	0.85	+0.22	+0.82	+1.03	+0.01
120º	1.15	+1.00	-0.58	0º	0.58	0.00	+0.58	+1.00	0.00
105º	1.04	+1.01	-0.27	345º	0.28	-0.01	+0.27	+1.00	0.00
90º	1.00	+1.00	0.00	330º	0.00	0.00	0.00	+1.00	0.00

Between 210º and 330º azimuths, the blades will not produce any force.

When the blades are between 180º to 210º and 330º to 360º azimuth, their thrusters will be producing a small amount of force in the for-aft direction that is opposing forward flight. However this force is very small and the majority of it is used to assist in the rotation of the rotor.

Re 4-blade Rotor:

Conclusion: It looks like a 4-blade rotor might work.

During Hover; consider that the 4 outlets in the blades are each producing 100% and Outlet 1 is producing 0%. This is a total of 400%.

During Cruise; consider that the 4 outlets in the blades are producing 100% and Outlet 1 is producing 300%. This is a total of 400%.

The following only considers the thrust from the rotor outlets. There will be additional thrust from outlet #1.

When the one advancing blade is at 90º azimuth it will be delivering 100% of the rotor created thrust. The components of this thrust are 100% longitudinal and 0% lateral.

When the two advancing blades are at 45º azimuth and at 135º azimuth they must each deliver 50% of the longitudinal component vector. They will therefor have equal but opposing lateral components of 50% each. The thrust of the vector must be 100% * 1.41 / 2 = 70.5% at each blade.

When the blade is at 0º azimuth and at 180º azimuth it will be delivering 0% of the rotor created thrust.

When one advancing blade is at 60º azimuth the other advancing blade will be at 150º azimuth. Their longitudinal vectors must sum to 100%. The lateral vector components of their thrusts must be equal, and of course they will be opposite. From the drawing (have not done it mathematically ~ yet). At 60º azimuth; the thrust is 87%, the lateral component is 44% and the longitudinal is 75%. At 150º azimuth; the thrust is 50%, the lateral component is 43% and the longitudinal is 25%. Therefore the total longitudinal as 100% and the lateral cancel each other.

The thrust of a single blade at various azimuths in the first quadrant is;

00º = 00%
30º = 50%
45º = 71%
60º = 87%
90º = 100%

The total rotor thrust will vary as the rotor turns and this might mean that the 'residue' thrust of Outlet #1 will pulsate at 4/rev. (Why will it?) Perhaps this will be offset, or made worse by the varying 4/rev parasitic drag of the outlets on the retreating side.

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While maintaining a constant forward component of the force from the blade(s) on the advancing side at all blade azimuths there must not be an oscillating lateral component. Vectoring the thrust from the blade root outlets might eliminate any lateral oscillation.

Additional Stuff:

The following is a bunch more un-thought thoughts.

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During takeoff and hover, it will take the force from all four blade-thrusters (2, 3, and 4 (& 5)) to support the craft.

In forward flight, the idea is that the craft is a part gyro and part helicopter,. The rotor is providing lift but it is contributing little or nothing to forward flight. The power to maintain rotor RPM will be far less than the power required to drive the craft forward, therefore much of the power is diverted from the rotor to the more efficient pusher turbofan (or whatever).

Why not apply this reduced rotor power to the blades on the advancing side only, since this is the side where the rotor will experience the greatest profile drag. The power on this side also augments the forward thrust of the turbofan.

The air to the blade's thrusters is probably gated so that in forward flight a blade start to exert thrust at 0º azimuth. This thrust will increase to a maximum at 90º azimuth and then decrease to zero at 180º azimuth. This would probable be done to minimize unequal cyclical in-plane forces, with the exception of the forward force.

The transition from 360º rotor thrust to gated rotor thrust will probable change in conjunction with the craft's transition from hover to forward flight. The RPM of the rotor may be slowed during forward flight.

Having the thrust at the root of the blade is probably not the most efficient location but it allows for an optimized blade profile. In addition, perhaps over-speeding of the rotor might be used to assist with take-off.

During forward flight (for example when the blade is a t 90º azimuth) the thruster on the blade will be pushing the blade and the craft ahead.

Yaw Control: Consider the bleeding off some of the air to the tail.

This rotor might lend its self to future advanced concepts, such as;

Low Tip Speed Design (large chord, slower RRPM)
Reverse Velocity Utilization
Independent Root and Tip Control

Would four blades or two blades offer any advantages?

Consider the implementation and possible advantage of fluidics at the exhaust ports to redirect the thrust, at different azimuths and different flight profiles.

Consider the 'fan' of the ultra turbofan being a radial fan located inside the hub.

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Outdoor test stand performance of a convertible engine with variable inlet guide vanes for advanced rotorcraft propulsion ~ X-wing

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870007392_1987007392.pdf

Additional Stuff:

If the rotor thrust is pointing slightly downward then

it will not add to the aerodynamic drag on the following blade.
It will provide some lift.
The heat from the exhaust will not affect the following blade.
The force vector of the thrust will have to be on or near the pitch axis at all pitch angles.
The thrust is less likely to interact with the following blade if there are only three blades.

Consider the possible need to have the central fuselage mounted thrust moved off the centerline toward the retreating side. This would allow it to be directed downward slightly. This would offset some of the roll force of the blade's thrusters. In addition, it will provide some additional lift on the retreating side, which cannot generate so much lift as the advancing blades can.

The drag on the roots of the retreating blades of the Sikorsky ~ XH-59A ABC at higher forward speed virtually drives the rotation of the rotors; see this page. This might mean that the outlets on the blades might be smaller than initially considered.

The outlets on the blades should probably be horizontal oval slots; to minimize drag.

The outlets on the blades may have their top trailing edge extend further aft the then their lower trailing edge. This may result in air being compressed in the opening of the 'sloped' outlets when they are on the retreating side during forward flight. The air might be then driven downward, which might result in the sloped opening providing a little lift .

Additional Thoughts:

Higher Thrust Velocity During Forward Flight;

Consider eliminating the stationary duct #1. This will mean that during forward flight the thrust coming out of the ducts on the advancing side will have a higher velocity.
This higher velocity might be beneficial considering that the free air passing the duct will be faster.
In addition, the internal piping of the airflow should be cleaner.

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Radial Turbine (Turbofan) as Alternative to Axial;

Radial turbine efficiency projected for year 2000 ~ .90.5

Axial turbine efficiency projected for year 2000 ~ .91.5

From; http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910014895_1991014895.pdf#search=%22%22radial%20turbine%20efficiency%22%20%22

Note that a propeller's efficiency is only about 85%.

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Ducted Fan;

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Flight Control;

Longitudinal and lateral cyclic may be controllable by the gating of the outlets in the same manner that is proposed for forward flight.

Alternatively Consider Trailing Edge Flaps:

And Interleaving - Landgraf ~ H-4

Maybe fluidics might work.

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A COMPARATIVE ASSESSMENT OF HIGHSPEED ROTORCRAFT CONCEPTS (HSRC): Reaction Driven Stopped Rotor/Wing And Variable Diameter Tiltrotor

http://www.asdl.gatech.edu/publications/1997/AIAA-97-5548.pdf#search=%22%22Reaction-Driven%22%20rotorcraft%22 ~ Have hard copy.

Concerns:

Rotation of the fan, with its vertical axis, will very likely yaw the craft in the opposite direction? What about making the fan a two 'disk' (or more) coaxial, to remove the torque? The fan could consist of many layers with the upper one being axial flow and the lower ones transitioning to radial flow at the bottom.

Would the yaw be balanced if the turbo-fan or ducted-fan were to rotate in the opposite direction to that of the single rotor?

If the flight controls are by varying the thrust of the blade outlets at desired azimuths there will not be any way to lower the collective pitch for autorotation. Consider an automatic closing of the outlets at the onset of autorotation; perhaps by using the thrust to hold them open. The closed outlets would have a negative pitch which would drive the rotation of the rotor???

If the flight controls are by varying the thrust of the blade outlets at desired azimuths there will not be any way to control the craft during autorotation.

A 4/rev force from the blade thrusters hitting the tail when a blade is at approximately 75º azimuth. However, the tail may be above the thrust.

How efficient is the dual serial aerodynamic power-train devices during hover? (i.e. Aerodynamic connection between turbofan and rotor.). How would the power required to hover this configuration compare with the power required if the force generator just faced straight down and gave direct lift (ala the Harrier)? Do the theoretical calculations sometime.

This appears to have some similarity to the above.

From Flight International ~ 18th - 24th Jan 2005

Propulsive anti-torque system could lead market fightback

In a revealing market-strategy clue to its next-generation commercial product line, Bell Helicopter executives say the proposed new family of aircraft may benefit from a breakthrough technology called a propulsive anti-torque system (PATS).

Developed as Bell's piece of a Lockheed Martin bid for the now-cancelled Unmanned Combat Armed Rotorcraft (UCAR), PATS replaces conventional tailrotors and tailfans with high-bypass engine power, adding perhaps 40kt (75km/h) dash speed while simultaneously serving anti-torque needs.

Bell's proposed new commercial offering - the Modular Affordable Product Line (MAPL) - has suspended development work on the new tailfan in favour of the PATS technology, says Dan McIlroy, senior vice-president of Bell's XWORX, a rapid prototyping and concept engineering team.

Bell's shift toward the breakthrough PATS technology is driven by recent feedback from a customer advisory panel, which warned Bell to avoid pursuing a "me-too" tailfan system and recommended the UCAR-derived system, says McIlroy.

The move also may reflect a seismic shift in Bell's market strategy over the past two years, which is now focused on recapturing a commercial market lead lost in the late 1990s to European competitors and doubling revenues within five years.

It helps that early development work on PATS has boosted the company's confidence in the technology. Analytical and scale-model testing during the UCAR programme "answered many of the physics and feasibility questions", says McIlroy, adding: "I think one of the challenges we're going to face is answering the question 'what are all the [market] possibilities?'"

PATS works by diverting heated air emitted by the turboshaft engine into one of three ducts - pro-torque, anti-torque or propulsive. A flow diverter manages the escaping air, channeling it into either left-and-right ducts in normal flight, or, in dash speed mode, closes the pro-torque duct and ejects the air out the back for propulsion.

The system is intended to overcome aerodynamic speed barriers for all conventional helicopter designs, which now limit light, single-engined helicopters to about 135-140kt top speed.

But McIlroy is quick to acknowledge several potential roadblocks ahead. "You have to slow the rotor down if you're going to be approaching these kinds of speeds," he says. "There's a whole set of control law and thermal dynamic law issues we have not discovered yet. We have to control this whole suite of systems."

STEPHEN TRIMBLE / FORT WORTH

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My comments:

It was part of the UACR proposals http://vtol.org/pdf/ucarvertfall04.pdf

It still consumes power solely to overcome main rotor torque, and perhaps more power than a conventional tail rotor would.

This Bell idea may have similarities with the Kaman Husky 'stovepipe'.

French Concept.

http://www.rotaryforum.com/forum/attachment.php?attachmentid=18215&d=1137567511

Additional Information:

Radial fans are not as efficient as axial fans. Would a mixed flow fan significantly improve the efficiency?

Axial, radial and mixed flow fans; http://electronics-cooling.com/html/2001_may_techbrief.html

There is a wide variation in efficiency between different fan designs (from as low as 40 to as high as 80 percent).

....because fans operate at their highest efficiency within a relatively small range. Outside of that range, efficiency drops off dramatically. Fortunately, the helicopter operates at a constant rotor rpm.

http://www.pnm.com/customers/tech_guides/PDF/P_PA_32.pdf

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From piolenc on Rotary Wing Forum July 1, 2007:

The best reference that I have found that covers tip-driven rotors is
Roy, Maurice: Theoretical Investigations of the Efficiency and the Conditions for Realization of Jet Engines. English translation published by the old NACA as NACA Technical Memorandum No. 1259. Part II, Helicoidal Reaction Propulsion Systems, is the relevant portion.
I thought it could be downloaded from the NASA technical reports server, but since their last major update to the interface I can't find it at all, for download or for purchase. Another, earlier report by the same author shows up, but not this one. The Cranfield NACA collection still has it, though:
http://naca.central.cranfield.ac.uk/...ca-tm-1259.pdf

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BMW 003 Radial jet engine. The BMW 003 was available earlier than the Jumo 004, but was less powerful and had more theething troubles. Type: BMW 003 Year: 1940 Country: Germany Configuration: Single-spool turbojet with seven-stage compressor, sixteen fuel burners, single-stage turbine. Length: 3534mm Diameter: 690mm Weight: 1252lb Thrust: 1550lb Revolutions: 9500rpm Consumption: 3240lbs/hr Usage: He 280, Ar 234C

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Consideration re mixed flow fan:

Further Thoughts:

The root thruster configuration, linked to in a previous post of mine, must deliver low-velocity high-volume airflow at the nozzles.

For efficiency this will require a large diameter fan to generate this airflow.

The large diameter fan will result in an opposing torque on the fuselage.

Possible solutions.

A second coaxial fan could be incorporated to counter this opposing torque.
If an electric motor is being considered for the power, considers mounting the frame of the motor coaxially and attached to the rotor (electricity provided by commutator). Then have an axial to radial fan above the motor drive ducted air to also drive the rotor around and/or the craft forward.

Since bigger is better (in respect to efficiency) would not two larger coaxial rotors be more efficient than the two large coaxial fans?

Now everything is going in circles. I'm going back to playing with twin main rotors ~ laterally disposed ones.

Similar Idea:

"Sud Aviation was formed on 1 March 1957 by the merger of Sud-Ouest and the Société Nationale de Constructions Aéronautiques du Sud-Est (SNCASE), or Sud-Est Aviation. Over the next decade, a number of compound helicopter designs were studied. In 1966, concepts were considered to add a jet engine to a helicopter, or use its single turbine engine to provide both shaft horsepower and thrust for forward flight."

Idea for Improved Forward Velocity: ~ posted to Rotary Wing Forum October 15, 2006:

Ga6riel,

Here is an 'off-the-wall' thought for an 'jet' driven rotor. The rotor might be; a tip jet, a root jet, a strip jet along the full or portion of the span of the blade, or some combination of the foregoing.

The intent is to provide a helicopter, which has a single main rotor, the ability to produce faster forward speeds. This would be accomplished by giving the jets the ability to redirect their thrust vectors at a rate of 1 per rotor revolution.

When the blade is on the advancing side, it's thrust will be aft and this will contribute to the rotation the rotor and the advancement the craft.

When the blade is on the retreating side, its thrust will have a downward component. This will partially contribute to the rotation of the rotor, but primarily it will provide lift on the retreating side of the rotor disk. This lift will mean that the pitch of this blade will be less, the drag will be less, the blade will not be subjected to tip stall, and the craft can fly with a higher forward velocity.

____________

A second possible feature of having a 1/rev variable thrust vector might be that the blades can have a rigid attachment to the hub, ala Kaman, and the thrust vectoring be used to provided pitch change for collective and cyclic control.

Dave

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Wild idea: Consider having a device like the visor on a helmet at the aft portion of the fan. Raising the visor 10-30º will allow the thrust to exit via Outlet #1 and it will 'scoop' some of the free velocity air stream into the top of the fan.

Radial Turbine ~ a Collection of Information On the Subject:

Gadd,

Radial Turbine

The radial inflow turbine has the advantage of ruggedness and simplicity, and it is relatively inexpensive and easy to manufacture when compared to the axial-flow turbine. The radial flow turbine is similar in design and construction to the centrifugal-flow compressor described in paragraph 1.19a. Radial turbine wheels used for small engines are well suited for a higher range of specific speeds and work at relatively high efficiency.

_____________________________

http://www-g.eng.cam.ac.uk/whittle/current-research/hph/radial-otl/radial-otl.html

http://books.google.ca/books?id=zPAFHyHctRUC&pg=PA43&lpg=PA43&dq=%22radial+turbine%22&source=web&ots=llAlsIKqwk&sig=tjyqXpBM1_zQnq8n3yh98pPiMWU&hl=en&sa=X&oi=book_result&resnum=5&ct=result#PPA45,M1

Words; Inward-flow radial turbine

Radial inflow turbine

Google

NASA

Possibly Relevant Information:

Source of High-Pressure Gas:

Loud Mouth Free Piston Engine: from Pascal

Coruis Engineering & Assoc. and Dynacam.bmp

Both files in -> C://Helicopter/Misc Files/ Coruis.pdf and Dynacam.bmp

Free Piston Engine Patents: from Pascal

US4589380[1].pdf
US4803960.pdf
US4924956.pdf
US5144917.pdf
US5174117.pdf
US5829393.pdf
US6349682.pdf
US6389811.pdf
US6431146.pdf

US1657641[1].pdf
US1785643[1].pdf
US2473204[1].pdf
US2711719[1].pdf
US2944535[1].pdf
US6694930.pdf

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And pictures in 4/29/2009 10:17 AM e-mail from Pascal.

Napier-Oryx Turbo Gas Generator Helicopter Propulsion

http://www.flightglobal.com/pdfarchive/view/1955/1955%20-%201077.html ~ Have hard copy

http://www.aviastar.org/helicopters_eng/percival_p-74.php

Pescara ~ gas generator: (free piston gas engine)

http://www.absoluteastronomy.com/topics/Opposed_piston_engine

Fire Piston! DIY Diesel Lighter

Pulse Jet - A Wacko Idea???

Is it possible to power the craft by a large single pulse jet engine that;

Is a coil and is located internally?
Induces a secondary airflow around the perimeter of the pulse jet, which lowers the temperature and 'softens' the sound and velocity of the thrust?
Consists of many individual pulse jets timed to increase the frequency of the sound and the thrust?

Is it possible to rotate the pulse jets at the same speed as the rotor and then vary the cycle of the pulsation, so that during forward flight it will only thrust when each exit vent is on the advancing side?

Notes:

The rotor will turn at approximately 600 RPM [10 cycles per second]. " For a small model-type engine the frequency may be typically around 250 pulses per second - whereas for a larger engine such as the one used on the German V1 flying bomb, the frequency was closer to 45 pulses per second."

Also see; Pulse detonation engine.

Outside information:

Patent: US 5,984,635 ~ Keller pressure jet rotor system

It is interesting to note that on Merrill Keller tip jet rotor only the retreating blades are receiving thrust. Posted by Arnie Madsen's post on Rotary Wing Forum

DATE:21/07/09

SOURCE:Flight International

Wind tunnel testing of a one-fifth scale-model exhaust gas driven co-axial rotor helicopter called Sherpa has been carried out by a Belgian consortium.

The Sherpa is a two-person helicopter with a dry mass of 540kg (1,188lb), a rotor diameter of 5.6m (18.3ft), a top speed of 129kt (240km/h), hover ceiling of 7,210ft (2,200m) and a 400km (216nm) range.

Its exhaust gas propulsion system is called Turbine Direct Driven Rotor or the acronym REDT.

Using the Belgian University of Liege's wind tunnel, the first campaign occurred in December 2008 and focused on auto-rotation qualities and fuselage drag.

A second campaign starting later this year will examine flight stability. A remote controlled one-fifth scale-model version of Sherpa has also been flight tested.

REDT uses a centrifugal compressor that feeds air to two piston engines and directly to the turbines that turn the co-axial rotors.

The direct bypass air is fed at 1.31 bar and 120° celsius while the piston engines, which also drive the compressor, also direct their exhaust gases to the rotors' turbines.

The company claims its REDT's benefits are a reduced number of moving parts, with no gearbox or tail rotor, and improved reliability.

Other Ideas:

Consider locating an electrically driven 'turbofan' [multiple rotating and stationary vane disks] at the root of each blade. Then pitch the stationary 'vanes' around the circumference so that the rotating blades are providing a fairly constant thrust when they are pointing toward the rotorblade's root as when they are pointing toward the rotorblade's tip. The thrust of each turbofan' will of course vary depending on whether the craft is hovering or flying forward; as per the primary concept of this page.

The drag of the turbofan housings may be excessive during forward flight when the rotorblade is near 0º and 180º azimuth.

Related Rotorcraft on this Web Site:

OTHER: Helicopter - Inside - Single Rotor - Tip-Jet (pinwheel) and Enhanced Flight-Control The pinwheel-jets deliver high velocity - low volume thrust.

Initially displayed: January 11, 2005~ Posted on Rotary Wing Forum: October 15, 2006 ~ Last Revised: January 12, 2012

The above utility invention is probably old news. However, it 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.