Transcript Recommendation of a Strategy
How to Select the Correct Gyroplane to Meet Individual Needs
There is no perfect design that does everything you desire in one gyrocopter, gyroplane or autogyro. However, it is easier today with so many new designs on the market.
Decisions, Decisions, Decisions
Decisions have to be made in order to select an aircraft that will suit where and the way you wish to fly.
You must think about stability and maneuverability for the various flight attitudes you intend on flying.
Do you feel a need to yank and bank or mainly straight and level sightseeing?
Every person is different so are your needs!
Every person has different needs from taking off in short distances on rough fields to pilots who takeoff from airport with only paved runways?
Other considerations are range and how much fuel you need to carry in order get to your destination, as well as the type of fuel your engine requires along your route and whether you intend to fly around the local area or fly cross-country at faster cruising speeds.
Stabilizers
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As the vertical stabilizer keeps the gyroplane from wandering ( yawing ) to the left or right.
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A horizontal stabilizer helps control the up and down pitch of a gyro-plane.
Our Past Safety Record
Gyrocopters were flown for years without horizontal stabilizers.
Sadly, during this time, we often had one fatal accident or more per month . Because the thrust line of the propeller was above the Vertical Center Of Gravity. Making the ship naturally unstable as it produced a torquing nose down moment with sudden power changes.
This caused a lot of new pilots accidents in what is called a Power Push Over or (PPO).
Modern Gyro-planes
Gyroplanes have become much safer now that most gyroplanes have added a large “true airfoil” Horizontal Stabilizer on a long moment arm placed directly in the path of the propellers thrust assuring the pilot will not need to become part of the pitch stabilization safety system.
Pitch Stability
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An aircraft is considered 'power' pitch stable if it doesn’t change pitch when power is added or removed.
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The aircraft should simply climb when power is added and it should descend when power is removed without changing pitch = nose up or nose down.
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Most ' airplanes ' have always been designed to be pitch stable .
Pitch Stability & Thrust Lines
Gyroplanes designs have three thrust lines.
Center Line Thrust (CLT), High Thrust Line (HTL), and Low Thrust Line (LTL) CLT HTL LTL
High Thrust Line
With HTL or High Thrust Line aircraft, you will discover that when you apply power, the nose will pitch down because the thrust of the propeller is position higher than the center of gravities fulcrum point. This causes the nose to drop and changes the angle of attack of the rotor-blades reducing lift and unloading the blades until the pilot pulls back on the stick to raise the nose back to level flight which will then reload the blades and reduce your airspeed.
HTL gyroplanes without an ADEQUATE HS are unstable as they produced a torquing moment nose down which caused a lot of accidents in the past in what is called a Power Push Over (PPO) and have cut off many tails too. Experienced pilot who are use to this instantly correct without mishaps.
An Adequate Horizontal Stabilizer is
very important
HTL without an adequate horizontal stabilizer to compensate will NOT respond the same throughout the entire flight envelope or power settings. HTL will always require some form of parasitic drag to compensate for its non CTL design.
At the very least it will make the non CLT aircraft less efficient, sluggish, and more ridged to control and at the very worst in a zero G event it could pitch over into a Power Push Over into the ground or cut off your tail unless the HS is large enough and positioned correctly.
High Thrust Line Example
Low Thrust Line Gyroplanes
Low Thrust Lines does the opposite of High Thrust line gyroplanes LTL aircraft make the nose want to torque/ pitch upward when applying power.
The pilot must push the nose down to stabilize the pitch, flight path, and airspeed.
LTL without a (true airfoil) or adequate horizontal stabilizer will also not be pitch stable or respond the same throughout the entire flight envelope or power settings. There are many experienced pilot who are use to this and instantly become the stabilization system and they correct without mishaps.
Low Thrust Lines & Zero G Events
Low Thrust Lines have one advantage over High Trust Line gyroplanes: In a zero G situation a small Low Thrust Line of 2” or less will pitch the rotors up changing the angle of attack thus reloading the rotor automatically. This could help eliminate the Power Push Overs.
Like HTL, LTL requires a larger HS to compensate for its non CLT design and will be less efficient, sluggish, and more ridged to control because you must add more parasitic drag to stabilize it.
Low Thrust Lines
To self stabilize LTL will always require some form of parasitic drag to compensate for its non CTL design.
At the very least it will make the non CLT aircraft less efficient, sluggish, and more ridged to control.
However fewer tails have been cut off than with HTL designs because the nose goes up and tail moves away from your rotors.
Low Thrust Line Example
Center Line Thrust is Pitch Stable
Your pitch will not change when power is added or taken away with a true Center Line Thrust gyroplane with a large “true airfoil” Horizontal Stabilizer on a long moment arm. It simply climbs or descends with power changes. If the power is suddenly removed CLT gyroplanes only slows up and goes into the best rate of glide for a normal approach. You can be much more confident in the aircraft's behavior flying a CLT aircraft without adding any parasitic drag to compensate because it is CTL.
Center Line Thrust Example
A CLT aircraft is balanced on the (CG) Center of Gravity fulcrum point so no change in pitch occurs.
Power Changes Pitch Stability Testing
To test your thrust line and Horizontal Stabilizer.
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1.
At cruising speed trim the aircraft for hands off level flight.
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Pull the power off until you enter slow flight and than apply pull power for 2 seconds then power off and back to full power repeat several times. The aircraft is considered Power Pitch Stable if the nose of the aircraft doesn't move up or down at all while applying power changes.
Climb Pitch Stability Testing
Climb attitude pitch stability test.
1.
Trim the aircraft for hands off level flight.
2.
Pull the stick back for two seconds until a 20 degree angle of climb is established.
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3.
Release the stick.
The aircraft is considered pitch stable if it doesn’t take more than THREE oscillations to return to straight and level flight.
Decent Pitch Stability Testing
Decent attitude pitch stability test.
1.
Trim the aircraft for hands off level flight.
2.
Pull the stick forward for two seconds until a 20 degree angle of dive is established.
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3.
Release the stick.
The aircraft is considered pitch stable if it doesn’t take more than THREE oscillations to return to straight and level flight.
Yaw Stability Testing
Left and Right Yaw stability test.
1.
Trim the aircraft for hands off level flight.
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2.
3.
Push the rudder left for two seconds until the aircraft yaws 20 degree to the left. Release the stick.
4.
Also repeat 1) – 3) using the Right rudder pedal.
The aircraft is considered yaw stable if it doesn’t take more than THREE oscillations to return to straight and level flight.
Your main choice is your intended use
Where will you be taking off and landing from most of the time.
What is the density altitude airfield in the summer?
The elevation and temperature of the airfield, road or dry lake bed where you intend to fly matters.
Airport Runway & Smooth Surfaces
What type of surfaces will you be landing and taking off from?
If you are flying out of a long paved airport or endless smooth dry lake bed, then an inexpensive straight axle and no prerotator may work for you.
If flying from smooth short runways then you will need a prerotator as it will reduce your ground roll significantly as you will not have to use the runway to slowly add power while you spin up your blades.
Off-Airport Rough Surfaces
Rough dirt fields or roads will probably require a faster turning prerotator and a landing gear with some form of suspension. The rougher the field the more suspension and faster turning prerotator you will need to assure you do not flap the blades and takeoff in the shortest distance.
Do you plan to takeoff from roads in crosswinds with bushes and tufts of grass alone it edge? Then you need to consider the height of the airframe to the center of gravity as tall long legged aircraft tend to 'Duck Walk' and could drift over hitting the grass and tip over.
Elevation & Temperature
What is the elevation of your takeoff and landing zones and even your locations temperature as well as your weigh needs to be calculated as each aircraft carries a different useful load?
Do need to fly over mountains at higher altitudes or is your local on the beach at sea level?
Are your winters to cold to fly without a header?
All of the above will help you make an informed decision to choose the gyroplane that comes closes to fitting most of your needs.
Density Altitude
Air density is perhaps the single most important factor affecting aircraft performance. It has a direct bearing on: 1) The lift generated by the rotors, propellers as reduction in air density reduces the lift.
2) The power output of the engine — power output depends on oxygen intake, so the engine output is reduced as the equivalent "dry air" density decreases and produces even less power as moisture displaces oxygen in more humid conditions.
Density Altitude...
If you live and fly at Sea Level then you can fly safely with less power and smaller rotor-blades. Some pilots choose to have two different sets of blades solely to assure the same performance at high- elevation fly-ins. Flying at 4000 feet and it gets hot, then you need a more powerful engine and larger diameter propeller and rotor-blades for those conditions.
Knowing your density altitude are important in order to select the proper horse-power engine, need for a turbo charger, and the size of the rotor- blades.
What type Airframe?
What type of airframe do you desire? Some of the following are things to consider:
Do you want a single-place, two-place tandem, or side-by side?
Do you wish to be out in the open with a view of everything, or is it too cold where you live, and you need a fully enclosed cabin with a heater?
All aircraft handle and fly differently depending on their fuselage shape, pilot’s weight, the engines power, propeller, and rotor length.
Fuselage Types
Three main fuselage types:
Open frame Semi/Partially enclosed Fully enclosed All come with 1 & 2 place, tandem or side by side
There are fewer 2 place side by side gyroplanes than tandem models.
Open Frame
For recreational flying open frame gets you out there in the elements.
It provides easy airframe inspection and is easy to maintain because you can see and get to everything.
It is the lightest and simplest type to construct.
Open Frame
The disadvantages are that it is the most un aerodynamic, more drag = less performance and in cooler weather you will have to wear cold weather gear.
Open Frame Ultralights
Recreational flight limited to single seaters is limited to 5 gallons of fuel and an empty weight of 254.
FAA does not require ultralights to have any proof of airworthiness.
Open Frame Ultralights...
No License required as the FAA does not certify ultralight-specific pilot knowledge and proficiency, but the FAA expects pilots to complete training under an FAA-recognized program.
Some gyro ultralight pilots fly “fat ultralights,” which are an aircraft that have added features that push it beyond the Part 103 performance or weight restrictions. Legally, such “fat ultralights” should be certificated as experimental amateur-built aircraft.
Partially Enclosed Gyroplanes
Partially enclosed gyroplanes have a nose section only, nose section and sides, or a nose section with roof and no sides.
These are heavier, and need more power to take off.
Partially Enclosed Gyroplanes
Not as easy to inspect, construction becomes more complex with strong mounting points for cabin sections to attach to, and increased tail surface area to counteract fishtailing effect from surface area of the cabin especially in cross-winds.
Partially Enclosed Gyroplanes
You have to install a pre-rotator, you cannot hand spin the rotors safely.
Advantages are reduced wind buffeting and chill factor.
It will cruise at a higher speed for the same given engine RPM compared to an open frame, as partial cabin reduces overall drag.
Fully Enclosed Gyroplanes
The Fully enclosed is probably the most comfortable to fly in with the fastest cruising speeds, total weather protection, and cabin heating/cooling.
Preflight inspections and maintenance will require opening enclosures to get to and see everything.
Fully Enclosed Gyroplanes
The fully enclosed is the heaviest of the gyros. They generally require reduction drives, use the most fuel and are most complex to build and generally cost more.
They need quite a large tail surface to counteract cabin surface area especially in crosswinds.
Performance
A high performance machine that spends most of its flight time in and around the general proximity of the airfield with a lot of low- level flying or yanking and banking will probably not cruise all that well.
It uses more fuel per hour going longer distances. It probably will not have a very high top speed.
If it has an aerodynamic cabin then it will probably have a higher cruising speed.
Cruising Performance
A cruising/cross-country designed aircraft will probably not get off of the ground as fast, but will achieve a higher top speed, and use less available power at cruise altitude.
This reduces fuel burn and your range significantly as will an aerodynamic cabin.
Also the taller the mast the more sluggish the gyroplane is.
What is your Height and Weight?
No design flies equally well for a big pilot or a small pilot without adding or subtracting ballast weight.
Only a very few gyroplanes have specific ballast point to adjust for different size and weight pilots.
A machine designed for a light pilot will wallow and be nose heavy carrying a big pilot.
A machine designed for a heavier pilot will probably be twitchy and tail heavy with a light pilot.
What Size
As bigger heavy pilots tend to be tall, and light pilots small, a light pilot flying a machine configured for a heavy pilot might find the flight controls a stretch to reach, while big pilots find machines configured for smaller pilots a squeeze.
Again only a few gyroplanes are designed to accommodate both. You need to sit in your selection and see whether you fit and whether you can reach the instruments while strapped in the seat-belt to make sure it is right for you before you buy.
What Range do you need?
An Ultralights advantage is no license required, most feel it's biggest disadvantage is its limited range and having to stay in the pattern. If you intend to fly longer than an ½ to ¾ of an hour, then an ultra-light’s limited fuel will not work for your needs.
You need to look at the routes you intend flying and measure the distance between fuel stops making certain the aircraft has the range you require.
Licenses & Current Ratings
Do you already have a pilot’s or sports pilot’s license?
For Fixed Wing pilots DO NOT BELIEVE that you do not need training.
Gyroplane take-off and to a lesser extent landing procedures are much different than Fixed Wing aircraft; therefore, you need training NO MATTER how many different types of aircraft you have flown
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Training
You are going to need training to solo, at least, no matter what gyroplane you select, even if it is an ultralight.
At least consider getting your Sport Pilot's license which will allow you to land at most airports in the USA. This will open up an entire new world to you with only a little more time required.
Build or Ready to Fly
Building takes time, generally far more time than you initially plan.
Do you have the time? The expertise needed varies with the complexity of the machine? Is it scratch built from plans or a kit? What support is around, pre-formed parts, etc.
Building provides flexibility in modifying as you go?
Select the Correct Kit
Choose carefully, and you will end up with a machine that is right for you.
You will probably finish and be happy with it.
Buying Used or Ready-made
Buying a pre-built machine gets you an aircraft immediately, but you miss out on learning every nut and bolt, and customizing it to your own preferences. Regardless of whether you build or buy, choosing carefully gets you a machine/design which suits hopefully most, if not all your intentions.
Any aircraft that has to be extensively modified to suit you will probably cause problems and cost more in the long run than buying a used gyroplane.
Engines: Two-strokes
Two-strokes have a relatively high output power for low weight.
Most two-strokes are cheaper and easier to install and use.
Disadvantages are that they are relatively unreliable and expensive to repair. Generally they are thirstiest on fuel as motor runs at high R.P.M.
Two-stroke fuels may require you to mix oil in your fuel; therefore, the fuel may be more expensive.
Engines: Four-strokes
Four stroke motors tend to be significantly heavier because of the stronger power strokes, heavy flywheel or propeller hub assemblies that are installed to help absorb them.
The weight of the engine generally needs a more complex engine mount.
Advantages are that they use less fuel per hour, are more reliable, and have a long operating life.
Four stroke and Maintenance
Most (non- aircraft certified) Four strokes may be easily maintained by the owner and have cheaper operating costs.
Parts are significantly cheaper, and they run on normal fuel.
Most give extended periods of max power without failing and operate for extensive periods between major services.
Direct Drive or Reduction Drive
Direct drive:
With the Direct drive the propeller is bolted directly to the motor and turns at the same revolutions as the motor. Direct drive system motors generally use significantly less fuel than reduction drives due to lower operating RPM.
Reduction Drive
Using Reduction drives the propeller is mounted on a coupling, either belt or gear driven to get the motor operating at a higher RPM than the prop.
The motor then generating more power, but the propeller is still operating at a reasonable RPM.
Average reduction ratio is around 2:1, or two revolutions of motor to one propeller revolution.
Generally reduction drives develop more thrust than direct drives.
Reduction Drives & Two-strokes
If you are going to use a two-stroke motor, you will have to use a reduction drive because the normal two-stroke power band is at too high an RPM.
Some Two-stroke motors in gyros have the reduction drives built in.
Drives & Four-strokes
Four strokes generally operate quite happily at the low 2800 to 3600 RPM ranges of direct drives.
However, to get lots of thrust out of a four stroke motor for two-seat gyros you may need to use a reduction drive unless it is a true aircraft engine that is already designed for the proper RPM range.
If your intended machine/design uses an automotive motor and if you or pilot/s is/are going to be inherently heavy then a reduction drive may be the only way to go.
Propeller Type
Propellers are used to propel the gyro forward.
How well they do that depends among other things on their curvature, diameter and pitch of the blade.
The diameter (length) of the blade in inches determines the size of the column of air pushed back, the bigger the better.
Pitch
The pitch, given in inches, shows the distance the prop moves forward in one revolution assuming 100% efficiency.
It also determines the amount of energy the column of air moving backwards has.
A good prop diameter/pitch combination is necessary to give you the flight performance desired.
Your Propellers Pitch
Coarse propellers load the motor using lots of power to turn. They produce good acceleration, but not so good cruise as you fly at 75 to 85% engine power all the time.
Fine pitch propellers use less engine power to turn so the motor will rev to a higher RPM producing reasonable acceleration and good cruise performance. Once up to cruise speed you are able to back off the power more to maintain cruise speed.
Propellers Length and Speed
At full power it is undesirable to have prop tips exceeding the speed of sound as a shockwave across the prop face decreases thrust. As tips go supersonic, they will be very noisy. The faster the tips after they go past the speed of sound, the greater the noise.
Lower propeller thrust is generated as shockwave increases in size.
Aim for a max RPM with tip speed about 80% of the speed
of sound.
Propeller Types
Propeller size, material and number of blades should be considered.
Propellers operate more efficiently with fewer blades. With more blades each hits some of the turbulence wake of the previous blade. The more blades the more engine power is required to turn the prop.
Low- power motors tend to have two- blade props, while high- power motors tend to have three or more blades to use the engines power providing even more thrust.
Propeller Materials
Propellers are constructed of wood, composites, or both.
Wood Propellers:
Wood tends to absorb harmonics and engine vibrations efficiently, hence their use on most direct drive four stroke motors. Wood props tend to be fairly inexpensive.
All propellers are effected by density altitude.
Composite Propellers
Composite material props cost more.
Sometimes over twice the price of wood, and do not absorb vibrations/harmonics very well.
They are usually slimmer built, and they can be more efficient than thicker wooden blades.
Composite material is easier to make three or more- blade versions. They tend to be used on high- power applications.
Rotor-blades
Rotors usually come in diameters between 22 feet to 28 feet.
Longer lengths of over 28 feet may be special ordered, or you may simply add a hub-bar extension.
Rotor materials vary:
Aluminum, composite, and wood.
Rotor-blade Diameter and Drag
Rotor diameter and twist in the blades are important.
In general a 22 foot set of rotors are relatively easy to push through the air if they have the correct twist in the blades. However, longer rotors take more power.
Rotor Loading is Important
With a heavy machine and small diameter rotors you will have to maintain high take-off, descent and cruise speeds.
With the difference between climbing, flying and descending only a few knots, the speed safety margin is smaller.
A light gyro and large diameter rotors will fly at quite low airspeeds, with a lower top speed.
Density altitude is a major factor here.
Rotor Loading is Important...
Longer rotors may be quite twitchy and balloon and float around the sky. Smaller diameter required for lighter gyros and larger for heavier gyros.
Most open frame single-place gyroplanes tend to use rotors between 22 to 25 feet.
Heavier single seat gyros, with partial/fully enclosed cabins tend to use rotors 24 to 27 feet depending on machine's weight.
Two seat gyros 28 foot plus rotors may be used.
Recap
Remember: an adequate HS and close to CLT
Ultralight, 1 or 2 place gyroplane
Tandem or Side by Side seating
Do you need a heater?
Open frame, partially enclosed, fully enclosed
Airfield surface determines your suspension needs
Your need to know Checklist.
Useful load = Fuel & passenger(s) weight and with your summer Density Altitude you can calculate: 1) 2) Engine : A) 2-stroke, 4-stroke, turbine or (electric in the future) B) Horse power needs C) Direct or reduction drive Fuel : A) Range in pounds of fuel you can carry
Your need to know Checklist...
Useful load = Fuel & passenger(s) weight and with your summer Density Altitude you can calculate: 1) Propeller : A) Length of blade limited by frame height B) Material A) Wood B) C) Composite Mixture of Composite and Wood C) Number of blades D) Pitch
Your need to know Checklist...
Useful load = Fuel & passenger(s) weight and with your summer Density Altitude you can calculate:
1) Rotors : A) Length of blades B) Materials: I.
II.
Wood Aluminum III.
Composite IV.
A mixture of any three above, I. Through IV.
Heavier blades hold their energy longer
lighter blades spin up more quickly.
Reminder
Since all decisions are a compromise, decide who will be flying it the most, where and what type of flying you plan doing the most.
I hope this helps in making a choice that will fit your needs and dreams now and in the future.
Sincerity, John Rountree