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I believe that Terrafugia is a new innovation in the field of flying car but it's not sufficient as it required special fuel and due to some more limitations shown. I think we required a flying car with ordinary fuel like (petrol, diesel or electricity). My concept is to do literature review on flying cars and light helicopters using ordinary fuel available in market. Later feasibility study on can we make a flying car in which we can eliminate limitations of Terrafogia as like; need of flat road, vertical takeoff is not possible, extra size of wings when spread and some more.
As now days use of ultra-light helicopters are widely in the field of commercial purpose as like (ambulance, police, and crop spraying game counting) and some of other purpose. According to market survey demand of ultra-light helicopters can be increases in future.
There are several benefits of using ultra-light helicopters not just they are economical even they are more reliable to use includes many other benefits like required less space, required less fuel, nippier in action, are more safe while turning also able to land in less space. Some of helicopters are in market as like kits and some are complete helicopters getting more interest of potential buyers.
However there are some disadvantages as well in use of ultra-light helicopters as they can't carry much weight as compare to normal helicopters. Even some times in case of air ambulance they can carry only 1 patient or just medicines not even a single patient. Another disadvantage can be safety as most of ultra-light helicopters are under research and not tested for every worst condition.
All above disadvantage can lead to another problem that is certificate for commercial or private use of ultra-light helicopters. As in some of countries ultra-light helicopters for private use is not allowed due to safety factors. But it is also another face that ultra-light helicopters are in commercial use in some of countries.
"Flying car or a road able aircraft is a vehicle that can run on the road as well as can fly like an aircraft whenever required".
Importance of flying cars:-
Now days most important problems in every country is traffic think about that time when you were going for some important and urgent work but you were stuck in traffic at that time you must be thinking about some mean so that you can fly over that traffic. This is the basic demand or requirement of flying cars. Flying car is nothing but a combination of road able vehicle that can fly as well whenever or wherever needed. We have to find another solution for traffic that can fulfil empty space of future transport.
If flying cars will be launched successfully then it will be a great achievement of human being. Flying cars can give many benefits over normal cars or ultra-light helicopters some of benefits are given below.
Flying car can be a better option that can solve problem of bad weather while traveling by plane for long way in that case it's not easy to land plane anywhere but in case of flying car it is possible to land car anywhere wherever you get space.
Flying cars are safer, efficient, cheap and pleasant mean of transport that can take place of future transport system.
Flying cars can help us to improve transport system. A current proposal by U.S transportation system is still in process that will show how flying cars can help us to improve our overall system.
In WWII era amply demonstrated that hundreds of small aircraft can fly in small airspace by just visual separation. The only problem that can occur in this transport system is weather that too is not a big problem if you are not flying for long distance and you can convert of aircraft in a road able vehicle.
1.1 INTRODUCTION ABOUT PHYSICS LAW:-
There were always wishes of humans to fly. Many of legends tried to fulfil this wish from earliest time. It started from the unsuccessful effort made by two Greek legends a father and son who made wings with wax and feathers. However it was still a dream until Wright brothers from Kitty Hawk, North Carolina done successful flying that leads to convert a dream in reality. It took so much time and effort by Wright brothers to develop first crude flying machine in Kitty Hawk and that journey still in development with some new improvement as latest modern aircraft available today.
There are some basic principles of flight, to understand tham you must start from the basic physical laws those are base of aerodynamics. Some of physical principles are given below.
In this chapter we discussed about basic flying principles to learn why and how aircrafts fly. All aircrafts fly on the basic principles of Newton's law of motions and Bernoulli's law of fluid flow. It's clear from this chapter that basic principle of lift generation is because of relevant motion of airfoil with respect to airflow. As airfoil has a curved shape this generates special airflow in the airstream.
This special flow pattern of airfoil creates a pressure difference between upper surface and lower surface of the airfoil. According to Bernoulli's low of fluid flow pressure difference also causes velocity difference. As airflow over upper side of the airfoil is high and low on the downside results in low pressure on upper surface of airfoil and high pressure on lower surface, this pressure difference try to develop a positive lift working from downward to upward and result in lifting force (thrust) for the airfoil. As airflow try to compensate pressure difference between upper surface and lower surface by applying some positive lift working vertically from lower surface to upper surface.
6.0 Basic calculation for thrust and weight for various engines :-
A BRIEF DESCRIPTION OF THE Ultra light Helicopter AK1-3:-
Design layout and construction diagram:-
The AK1-3 helicopter is an ultralight structure consist 3 blades on main rotor and 2 blades on tail rotor.
Thos ultra light helicopter uses Japanese Subaru EJ25 engine which is one piston liquid cooled. This engine is place just behind the cockpit.
6.1.2 Main Features:-
Maximum takeoff weight 650 kg
Maximum weight of loaded helicopter without fuel 590 kg
Maximum payload weight (including pilot and fuel) 270 kg
Empty helicopter weight 380 kg
Helicopter equipment weight 25kg
crew (2 persons) 160 kg
Maximum ground airspeed 186 km/h
Ground cruising airspeed 160 km/h
Rotation speed around vertical axis during hovering < 45 degrees/s
Maximum ground climbing capacity 8 m/s
Minimal vertical descent rate while floating in autorotation regime at VDesc=90 km/h 7.4 m/s
One horizontal piston four-cylinder four-act liquid-cooled engine Subaru EJ25.
Engine working volume 2500 cm3
Engine power 165 hp(121 kW)
Engine dry weight 110 kg
Geometrical adjectives of the rotor
rotor diameter 6.84 m
blade number 3
blade profile NACA 63012/63015
outline blade shape rectangular
peripheral velocity of blade tip 205 m/s
duty factor 0.0475
Geometrical adjectives of the anti-torque rotor
rotor diameter 1.28 m
blade number 2
carrier blade chord 0.115 mm
blade profile NACA 63012
peripheral velocity of blade tip 186.3 m/s
duty factor 0.1144
6.1.3 Some calculation about lifting force (thrust):-
Basic principle of helicopter is a bit different as compare to plane as like in case of helicopter force that works on rotor blade helps helicopter to fly called as lifting force. But in case of airplane same force called as thrust. Thrust can be described as force developed by tail rotor in case of helicopter. Here in this chapter we will discuss some calculations about weight to thrust calculation for those engines can be use in flying cars. These engines are very light in weight and create more power.
Petrol engine (Subaru EJ 25) engine:-
Max power generated: - 165hp
Speed of rotor=9000
Total weight of engine= 110
Max takeoff weight = 650 Kg
(If you are using rotor blade of AK1-3 helicopter R= 11.22 ft)
The first step is to measure the diameter of the rotor or propeller and calculate the area in square feet. Area is defined as:
= 395.28 ft2
Power loading =0.417 hp/ft2
Where "power" is the power delivered to the rotor or propeller and A is the area, calculated above. This is very important---approximately 10 to 15 % of the engine's power will be delivered to the tail rotor to counteract torque. This number obviously varies but 10 to 15 percent is a good starting point. If you have a 100 horsepower engine in your helicopter, expect only 85 to 90 horsepower to actually get to the main rotor. Additionally, you would need to reduce the power by an additional small percentage to account for frictional losses in the drive system. In the case of a tandem rotor helicopter such as the Chinook or meshed rotor like the Kmax, all of the power will be delivered to the main rotor and this in fact is the reason those helicopters are so well suited for heavy load lifting operations.
Using the parameter PL [hp/ft^2], we use an empirically defined formula to calculate the thrust loading (after McCormick). Thrust loading is in the units of pound per horsepower and is a function of power and rotor disk area. Thrust loading (TL) is calculated:
Thrust Loading (TL) = 8.685 x PL(-0.3107)
= 8.685 x 0.417(-0.3107)
= 11.397 lb/hp
=1880.50 lbs (852 kg) weight
*note: Calculation results are in pounds-thrust, NOT pounds-mass
6.1.4 Petrol engine Mazda RX-7 Wankel engine:-
Max power generated: - 280 hp
Speed of rotor=9000
Total weight of engine= 122
(if you are using rotor blade of AK1-3 helicopter R= 11.22 ft)
The first step is to measure the diameter of the rotor or propeller and calculate the area in square feet.
Area is defined as:
Power loading =0.708 hp/ft2
Type of Engine
Thrust Loading (TL) = 8.685 x PL
= 8.685 x 0.708(-0.3107)
= 9.66 lb/hp
= 9.66 x 280 = 2704.8 lbs (1226kg) weight
*note: Calculation results are in pounds-thrust, NOT pounds-mass
In this chapter we have done some basic calculations about weight to thrust (lift) ratio i.e. power required to lift weight. From calculations it is clear that weight is a major parameter to be considered while designing an aircraft.
While considering Subaru EJ-25 engine which is a petrol engine used in ultralight helicopter AK 1-3 engine is giving 165 hp at 9000 rpm and weight of empty engine is just 110 kg. So this engine is much more suitable as compare to some of other petrol engine. This engine can lift about 852 kg weight on full engine power. But you need to reserve 15% power for tail rotor and transmission losses. As per ultralight light helicopter AK1-3 data it can lift up to 650 kg of weight efficiently.
In other calculation we have done some calculations on Mazda RX-7 (Wankel Engine) i.e. one of those light weight engine that give 280 hp at full power. If we will use other parts same like (rotor blade, controlling system) used in Ultralight AK1-3 than Wankel engine can lift about 1226 kg of weight. But if you will reserve 15% power than still this engine is much more capable to lift weight more over total weight of empty engine is just 122 kg where weight of Subaru engine is 110 kg.
It is clear from above calculations that some of engines are capable to replace jet engines in the field of flying cars.
7.2.1 CALCULATION PROCEDURES:-
For the here presented analyses, the take off mass of m = 650 kg has been considered as a constant input value. For operational purposes, mass should be varied within the predefined range. Initially, an optimization procedure had been applied to determine the most relevant calculation inputs.
Considering the main rotor, the most relevant parameters that were obtained are:
Mass of helicopter =650kg
Pay load =180kg
Hover ceiling =1000m
Cruising speed =160km/h
Number of blades = 2,
Rotor radius R = 3.8m,
Blade chord length c = 0.205m,
Solidity factor of the rotor =0.0343,
Area of rotor disk A =45.96m2,
Number of revolutions per minute N = 440 rpm = const. for all flight regimes,
blade tip tangential velocity Vt = 175 m/s = const.
The reciprocating power plant gives the Maximum output of at the sea level.
On other altitudes engine power can be determine as: (1)
Where represents air density at H = 0 m, and
Is density at other altitude, defined by equation (2)
In which H is altitude measure in meters
Calculations for Lift Coefficient of Main Rotor:-
The average blade lift coefficient can be determine by
Where CT denotes thrust coefficient in hovering and level flight can be calculate as:
CT is average thrust coefficient,
R is radius of blade,
Is average blade lift coefficient
T trust and T =W = m* g.
V is progressive flight velocity constant
And eq-4 will be same for progressive flights and hovering. But for higher calculation this eq. will refined by including the disk slope angle and collective pitch.
Calculations of Power Required for Hovering and Horizontal Flight:-
Total power required for hovering and horizontal flights will be 10% more to take in to consideration of power required for tail rotor and transmission losses.
TWhere Cp represents coefficient of power for main rotor
For hovering (6)
For horizontal flight (7)
Where represent a coefficient for velocity distribution irregularity over the main rotor disc.
Value of for hovering =1.15,
Value of for forward flight =1.2; , where
V is progressive flight velocity constant
Drag of helicopter excluding rotor is
From eq-8 we can calculate value of (RD )
Denotes induced velocity coefficient in progressive flight s obtained from equations [Ref]:
And represents equivalent area of the plate
Is the velocity of main rotor during hovering;
Is the velocity of main rotor during forward flight
Then from equation [Ref]
We can find?
By putting value of (RD from eq-8 and value of Æ›i from eq-9 ) in eq-7 we can find out value of CP
Calculations according to given data:-
Where Ïo (Density of air) = 1.22 kg/m3
as initially H=0 then (Ï=Ïo)
Now main rotor blade lift co-efficient (CL)
Power Required for Hovering and Horizontal Flight
Power required for hovering:
TBut power required will be 10% more to take account of power required for tail rotor and transmission losses:
Power required during horizontal flight:
If H=0 than V will be 0
So µ and RD will be zero, by putting all these values in above equation
8.1.3 Gearbox design:-
There are several different gearboxes available in market for different power ratio but you need to justify that which gear box will be suitable for your aircraft. For a flying car you can't select very heavy and complex gearbox as it can increases overall weight of car. As weight is most critical point so heavy gearbox will directly effect on overall feasibility and efficiency of aircraft. Here we have done some calculation for Mazda RX-7 Wankel engine considering same power output as used for thrust calculation.
Calculations for Gearbox:-
Type (Wankel engine) Mazda RX7
Max power 250hp (186kw)
Speed of Rotor 9000rpm
Total weight of engine 122kg
As per average calculations power transmission (speed of rotor) to the main rotor blade should be about 1:7 but as speed of engine is 9000 rpm so considering main principle for rotor speed that blade tip velocity should not reach to equal velocity of sound.
Considering above conditions for gearbox design;
No. of teeth on 1st gear= n1
No. of teeth on 2nd gear = n2
No. of teeth on 3nd gear = n3
Speed of 1st shaft= N1 rpm
Speed of 2st shaft= N2 rpm
Speed of 3rd shaft= N3 rpm
Speed ratio for main gear= speed ratio for pinion (1)
Speed ratio for main Gear=
Power in at shaft (1) = 9000rpm
No of teeth on gear (1) = 67
No of teeth on gear (2) = 17
Then from gear ratio equation -
This will be maximum power can be transfer to the tail rotor.
Now power out from gear (2) will be power in at gear (3) i.e. 2283.58
Then from gear ratio equation -
So this gearbox will give 951rpm at main rotor blade so that blade tip velocity will not reach equal to speed of sound.
9.1 Use of Rapid prototyping:-
Now days most of the aerospace, automotive and automobiles companies are looking for most effective processes i.e. Rapid prototyping and Additive manufacturing for product prototyping in shorter time with high precision quality. In this chapter author will discuss role of rapid prototyping and additive manufacturing in development of existing or traditional manufacturing processes. This chapter will also introduce how RP and AM processes helped author in project. RP and AM processes are mainly concentrating on design and manufacture of prototype product for prototyping and testing purpose without actually making part. This process will help to reduce time and cost required for prototyping and testing so that results required for manufacturing can be obtain in less time with reduced cost. This project is all about feasibility study of flying cars, prospective design and parameters of authors flying car concept. In this chapter author has discussed steps and processes involved for designing, analysis of flying car as per assumed data with the help of RP and AM process have been discussed below;
9.1.1 The paper design :-
Paper design is the first step for designing and manufacturing any product. Paper design gives us an idea and rough design parameter bout basic design. Paper design also allows you to think and modify your design according to situations and requirements. This is the basic steps of any innovative and new design.
The base of this project was to eliminate limitations and disadvantages of Terrofugia (flying car) i.e. a successful flying car available in market. Although this car is one of the best flying car available in market but still there are some limitations as well. These limitations results in and innovative idea in authors mind to design and work for a flying car that can fulfill all limitations of terrofugia. The first design that gives a direction to the concept is given below;
This design gives a basic overview about flying car concept that its better to use basic principle of helicopter to design a flying car instead of utilizing concept of jetplanes. As the term flying represents a vehicle that can run on road and can fly when required as like in traffic, to cross hill or to cross river but as jet plane required flat road about 1000 m to takeoff. And that doesn't fulfill need of flying cars.
9.1.2 Design analysis and visual prototyping :-
To begin designing a Car, designer has to determine basic purpose, requirement and way to get it. As it is clear from above paper design that authors concept for a flying car is based on basic principle of helicopters. So first we need to understand basic principles of helicopter design, limitations and critical features of helicopters should take care about. Author has discussed all these point in chapter 1 and 2 that helps to get an overview of helicopters and prospective flying car. After all calculation of basic requirements for designing a flying car we can design paper sketch in any 3D designing software (solid works) that will give us a visual and mathematical overview of design. Virtual prototyping can be most important and beneficial step that can helps to understand design compatibility and issues. Virtual prototyping is an advanced designing technique that allow designer to see prototype in artificial representation mode that seems just like actual environment. Virtual prototyping is a part and benefit of Rapid prototyping technique. After designing individual part and assemble them in solid works visual prototyping helps to justify whether design is feasible or not. After all design analysis next step will be feasibility study and prototyping of design.
9.1.3 Feasibility analysis and Prototyping:-
After 3D design and visual analysis next is using simulation software, aerodynamic study and motion study for feasibility of individual part design. So that several parameters of design can be justify by designer. This segment basically concentrate on utilization of various software's of rapid prototyping available for study of different properties. Prototyping allow designer to analysis behavior of parts and properties such as propulsion, distance, traction and speed in actual working condition and give enough space to make any changes required.
9.1.4 Rapid Prototyping:-
After all analysis on 3D models and virtual design if design ensure better performance, the designer may print that car on any rapid prototyping to produce a prototype part. It's better to print a paper base prototype on initial stage to ignore any major error that will effect on overall cost of prototyping. Paper base prototype is a combine set of parts manufactured layer by layer cutting of paper sheet. This prototyping will ensure physical design and virtual prototyping of design.
This portion includes various testing and analysis should be done on prototype as a scaled model of design. It's not necessary to make actual part for analysis purpose as some of properties can be determine in prototyping testing. In case of cars (or flying cars) you can determine stresses in various parts, fluid flow and some of other parameters so upgrade quality of design.
Sometimes RP and AM helps to identify most suitable material or other parameter under different environmental conditions. Analytical data collected from testing can help to make some changes in existing design and materials. Moreover from tender point of view its most important step to make a prototype that can generate interest of investor to invest more money for that particular project. We all know about human tendency that its easy to understand a visual and prototype part instead of just a design. This portion has important role in product development process to convince other people or company for changes in existing design. Some of virtual prototype testing concepts are given below;
Physical point of view:-
Calculation of center of mass and distribution of weight
Finite analysis method
Effect of Size integration on element
Basic Steps In Engineering Design:-
Data required for design and functional mode
Desire output and need of product
Theoretical and Experimental data collection as well as analysis
Basic design and modeling on the basis of principle information
Analysis and testing on scaled prototype model
Manufacturing planning and Management
After completion of all testing on prototype model next step is to analysis results and redesign that design for improvement and maximum performance that can be achieve after some modifications. Redesigning allow designer to identify problems and make desire correction with in design space that explore designing skills for any individual person. For example: In case of automobiles available torque depends on rim size (wheel diameter) and spring width. So for designer can select different diameter wheel to make a chart for torque available on different wheel diameter. That will help to select proper wheel diameter except extreme case.
Virtual design help designer to aid process of redesigning such as virtual race in which designer compare between two different designs and identify which design is more suitable as in terms of speed. These are some of steps and advantages that come in redesigning process.
Utilization of Rapid Product Development and Additive Manufacturing in development of existing technology:-
In this thesis author tried to developed a simple gearbox required for flying car. This gearbox is design according to above calculated data in chapter 8. But this gearbox has been design according to theoretical value and still need to consider mechanical losses, strength and life estimation. So author has done some testing of stress analysis on each gear during gear meshing with the help of FEA software. This software will help to determine maximum stress value during gear meshing and also show critical area, common steps includes in FEA analysis have discussed below;
FEA(Finite Element Analysis):-
1) introduction to Contact function :-
Let us assume two simple gears are in meshing during power transmission and generally named as object contacts. One of the surface known as main contact face while gear meshing. Gear transmission system have broad flexibility during operation it can change velocity direction and other functions as well. The maximum strength, stress and impact produce by gear surfaces during meshing of a power transmission by gear meshing.
These properties results in limitations and failure of a gear for example: plastic flow of gear tooth, face wear on tooth, gear break off and any other problems. Simulation study of any gear meshing is a important analysis to make sure successful operation of any gearbox. Simulation method can help to find and analysis contact area, contact position and maximum strength during contact, distribution of stress over the gear and plastic flow rule can be also determine through simulation analysis. It can help to determine maximum stress that can cause failure of gear and also helps to improve design of gear to get maximum efficiency as well as maximum life cycle of gearbox.
2) Modeling Steps:-
There are some specific steps includes in modeling of any part, basic steps of modeling through FEA method are discussed below in a flow chart:
1) Create the part
In this section first step is to save design file in IGES or STL format from designing software that was used for designing of gear. Overall gear should be define as a set of geometry. All surfaces as like: end surface, main slot and axis hole should defined as surf gear inner and rest of surfaces known as surf gear contact.
Simulation process mainly focus on stress analysis on gears instead of stress analysis on shaft. Generally stress act on shaft is much less as compare to stress on gear, so we can neglect stresses on shaft in dynamic analysis.
The zero point known as the reference point and surf axis demotes outside surface of the gear. Both gears should be build in the same parameters.
2) Define material property
Second step is to define materials property for gear. There is wide range of materials in simulation software so that you can select material from them as per your requirements.
Gear assembly is the third step of modeling in which both gears and axis should be assembled as dependable part. A assembly of two gears during meshing is shown below in fig.
Steps for analysis
For the dynamic analysis of gear a geometry non linear button should click that generates a 3D FEA model for characteristic analysis. This 3D FE deformable model of gear can help to get accurate results but on the other side there are few disadvantages of 3D FE deformable model as it takes longer time and more effort in analysis and calculation. For example: two gears given below have 8238 mesh that will require about 1 week for meshing that is also on 3GHz processor with at least 1 GB memory. Steps given below will define contact area and output strength during contact.
Specifications of FSC-1
Length: 19 ft 0 in (5.79 m)
Wing span: 33 ft 4 in (10.16 m)
Height: 7 ft 10 in (2.38 m)
Max. takeoff: 3,800 lb (1,727 kg)
Empty equipped: 2,497 lb (1,135 kg)
Max. speed: 261 knots (300 mph, 483 km/h)
Cruising speed: 225 knots (260 mph, 416 km/h)
Take off speed: 63 knots (73 mph, 117 km/h)
Minimum landing speeds: 60 knots (70 mph, 111 km/h)
Minimum landing distance: 455 feet (140 m)
Take off distance: 476 feet (145 m) using patented "Rear-Wheel Powered Assist Takeoff"
Take off distance (Nominal): 1231 feet (375 m)
Initial climb: 2,438 ft/min (804 m/min)
Service ceiling: 34,100 ft (10,400 m)
Range: 845 nautical miles (1,565 km)
Width: 6 ft 8 in (2.03 m)
Length: 18 ft 2 in (5.79 m)
Height: 4 ft 10 in (1.47 m)
Max. speed: 180 mph (156 knots, 290 km/h)