Lab 1 (Loftin) and Intro Flashcards
What are the three main flight vehicle classifications?
Aircraft
Space Access Vehicle
Spacecraft
Lecture 0–Slide 3
What are the three main ways that fixed wing aircraft are categorized with respect to function?
Civil
Military
Research
Lecture 0–Slide 4
What are the typical organizational schemes of senior capstone projects for aerospace engineering?
- Design-Build-Fly
- Individual/Team Project
- AIAA Design Competition
- Industry Sponsored/Monitored Project
Lect 1 – Slide 4
Form follows ______.
Function.
Lect 1 – Slide 6
What was the central argument of the Sears-Foa debate?
The range of the flying wing and more generally the applicability for military bomber applications.
Lect 1 – Slide 8
The “struggle to harmonize the balance between design proficiency available vs. design proficiency required over a 70-year period” was mentioned with respect to what case study?
The Sears-Foa debate over the range of a flying wing.
Lect 1 – Slide 8
Who are William R. Sears and Irving L. Ashkenas?
Two engineers for Northrop that worked to develop YB-35 flying wing bomber.
Lect 1 – Slide 8
What was Foa’s concern with respect to the flying wing analysis presented by Ashkenas and Sears?
The maximum range proclaimed by Spears and Ashkenas was actually a minimum.
Lect 1–slide 9
What are the four isolated generations of flying wings?
Hint: What companies spearheaded the first four phases of flying wing aircraft design?
- Horten
- Northrop 1
- Northrop 2
- Airbus/Boeing
Lecture 1 – Slide 15
What are three unique emphasis points of the aerospace capstone?
- Solution Space Screening
- Solution Space Visualization
- Multi-Diciplinary risk assessment
Lecture 1 – Slide 16
What are the
“ladder steps” in the capstone learning objectives (from bottom to top)? Which is the most important?
- Analyze
- Integrate
- Iterate
- Converge (most important)
- Screen
- Visualize
- Assess Risk
Lecture 1 – Slide 17
In terms of the design ladder, undergraduate education primarily focuses on which step?
Step 1–Analyze.
Lecture 1–Slide 17
Who founded skunkworks?
Kelly Johnson
Lecture 1 – Slide 18
What are the two main classifications of subsonic/transonic commercial airplanes?
- Prop
- Jet
Lecture 1 – Slide 39
What are the two main categories of supersonic commercial aircraft?
Supersonic Buisness Jet (SBJ)
Suspersonic commercial transport (SCT)–First Gen, and 2nd gen
Lecture 1 – Slide 50
Give some examples of 1st generation Supsonic commercial transports (SCTs).
- Concorde
- Tupelev Tu-144
- Boeing B2707
- Douglas AST
Lecture 1– Slide 50
Why does Loftin’s method not require iteration?
Due to the way the empty weight formulation is calculated.
Hypersonic Convergence – Slide 3
In Loftin’s approach, empty weight is correlated with __________ instead of _______.
Power Loading
TOGW
Hypersonic Convergence – Slide 3
List all six steps for the Roskam design process.
- Guess TOGW
- Determine We from regression
- Determine Wf from the trajectory
- Calculate Performance constraints
- Determine S and T from TOGW_new
- Iterate until TOGW is converged
Hypersonic Convergence – Slide 4
Conventional sizing methods for subsonic/supersonic aircraft only _______, leaving the _____ and ____to be sized independently.
wing and propulsion system simultaneously
fuselage and empennage
Hypersonic Convergence – Slide 8
To size a hypersonic vehicle, the sizing methodology must _____________.
Consider the total integration of the system simultaneously. In other words, all aspects of the design must be considered simultaneously.
Hypersonic Convergence – Slide 8
Explain how hypersonic convergence considers the total integration of the system simultaneously.
By explicitly including volume in the convergence logic and defines both the weight and the volume associated with all critical components.
Hypersonic Convergence – Slide 8
For a hypersonic vehicle to be capable of useful missions a single blended body must generate/include what main four items?
- Volume
- Lift
- Thrust
- Control Forces
Hypersonic Convergence – Slide 9
Hypersonic convergence relies on solving how many core equations iteratively?
Two equations. The volume budget and the weight budget.
Hypersonic Convergence – Slide 11
In the hypersonic convergence equations, which parameter is integrated until the weight and volume budged equations coverage?
The planform area.
Hypersonic Convergence – Slide 11
What is Kuchemanns slenderness parameter?
A nondimensional parameter which relates the volume of the vehicle to its planform area.
Hypersonic Convergence – Slide 12
What is the definition (mathmatically) of Kuchemann’s slenderness parameter (tau)?
tau = V_tot / S_pln^(3/2)
Hypersonic Convergence – Slide 12
What are the three required initial values for hypersonic convergence?
- Range of Tau
- TOGW
- Planform area (S_pln)
Hypersonic Convergence – Slide 14
What does the term K_W refer to in hypersonic convergence methodologies?
The ratio of the wetted planform area to the total platform area.
Kw:= S_wet/S_pln
Hypersonic Convergence – Slide 18
What is the analog for Loftin’s performance matching in hypersonic convergence?
Constraint analysis
Hypersonic Convergence – Slide 23
And hypersonic convergence what are the primary outputs of constraint analysis?
The thrust to weight ratio (T/W).
Hypersonic Convergence – Slide 23
In hypersonic convergence what is the objective of the trajectory analysis?
Compute the fuel fraction required to perform the specified mission.
Hypersonic Convergence – Slide 27
In hypersonic convergence trajectory analysis, what is the definition of the fuel fraction?
Weight of the fuel divided by the takeoff gross weight.
ff = W_fuel / TOGW
Hypersonic Convergence – Slide 27
What is the “heart” of the hypersonic convergence process?
The wight and volume budget.
Hypersonic Convergence – Slide 29
Fundamentally, the hypersonic convergence process can be through of as _____________.
The solution of two algebraic equations. The two equations are the weight budget and the volume budget equations.
Hypersonic Convergence – Slide 29
In the hypersonic convergence logic, when is convergence attained?
When the initial takeoff gross weight and the new takeoff gross weight are approximately the same.
Hypersonic Convergence – Slide 37
From what period what the “time of little change” according to Loftin?
1918–1926
Lab Mod 1 – Slide 12
During the period between 1918–1926, general aviation in the US consisted of?
Barnstormers mostly utilizing surplus Curtiss JN-4D Jenny’s.
Lab Mod 1 – Slide 12
During the period between 1918–1926, why was wing loading kept low?
To operate out of existing airfields with short runways. Low wing loading corresponds to low stall speeds. This allows pilots to use shorter runways.
Lab Mod 1 – Slide 12
What was the first airplane to utilize a wing with greater than 6 to 8 percent thickness ratio?
The Fokker Trimotor
Lab Mod 1 – Slide 14
During the period between 1918 and 1926, what was the primary driver of airplane development?
Air races with high speed aircraft.
Lab Mod 1 – Slide 14
From the Loftin study, what period was the “Time of revolution?”
1926 to 1939
Lab Mod 1 – Slide 16
During the period between 1926 to 1939, what plane popularized the monoplane configuration?
The Ryan NYP
Lab Mod 1 – Slide 17
What was the first aircraft in the US to employ a smooth all-metal stressed skin semi-monocoque type structure?
The Northrop Alpha
Lab Mod 1 – Slide 19
What was the first aircraft that allowed airline companies to make a profit off passenger transport and not just the mail?
The DC-3.
Lab Mod 1 – Slide 20
Why is the Loftin approach still valid today?
Because the evolution of prop-driven aircraft has mostly stagnated since the advent of jet aircraft.
Lab Mod 1 – Slide 2
What was the education, employment, and position of Lawrence K. Loftin?
- University of Virginia
- NASA Langley
- Director of Aeronautical research
Lab Mod 1 – Slide 2
According to Loftin, the evolution of the modern aircraft can be characterized by _______________.
A series of technological levels which extend over a period of years.
Lab Mod 1 – Slide 2
According to Loftin, why was there little a/c development between 1918-1926?
The prevailing attitude after WWI was that there would not be another major armed conflict. Aircraft research suffered as a consequence.
Lab Mod 1 – Slide 12
What aircraft did Charles Lindbergh fly from New York to Paris?
A Ryan NYP
Lab Mod 1 – Slide 16
What was the Lockheed Vega’s claim to fame?
It had the highest level of aerodynamic efficiency achieved by a high-wing monoplane with fixed landing gear by 1930.
Lab Mod 1 – Slide 17
Why was the Lockheed Orion only produced in limited quantities?
The Orion was a single-engine aircraft. In the late 1930s, government regulations disallowed the use of single-engine aircraft for scheduled passenger-carrying operations.
Lab Mod 1 – Slide 19
The B-17 bomber incorporated the technological advances of the DC-3 and the Boeing 247D but varied in what respect?
The B-17 has four engines instead of two.
Lab Mod 1 – Slide 22
The first aircraft which assembled most of the advanced design characteristics of the 1930s was the _________.
Boeing D47
Lab Mod 1 – Slide 19
What were some of the “synergistic” design features of the Boeing 247?
- Cantilever wings
- Retractable landing gear
- Radial engines
- Variable speed, constant speed props
- Single-speed geared turbocharger
- All metal stressed skin structure
- IFR instrumentation
Lab Mod 1 – Slide 20
Why did the Boeing 247 have a low wing loading?
Because it did not have any high-lift devices.
Lab Mod 1 – Slide 20
True or False
The DC-3 incorporated all the advanced technical features of the Boeing 247 and the Douglas DC-2.
True
Lab Mod 1 – Slide 20
How many passengers could the DC-3 carry?
21
Lab Mod 1 – Slide 20
Why does the DC-3 have a higher zero-lift drag coefficient than the Boeing 247?
The DC-3 has a larger fuselage. It therefore has a larger ratio of wetted area to wing area.
Lab Mod 1 – Slide 21
How do the lift-to-drag ratio values compare between the DC-3 and the Boeing 247?
The L/D value for the DC-3 is slightly higher than the Boeing 247 (14.7 vs. 13.5). The higher aspect ratio of the DC-3 accounts for the discrepancy.
Lab Mod 1 – Slide 21
What are the three aircraft associated with the so-called “final configuration” of prop-driven aircraft?
- The Douglas DC-3
- The Boeing B-17
- The Seversky XP-35
Lab Mod 1 – Slide 22
What post-1930 aircraft is generally associated with a low purchase price, operation, and maintenance cost while being easy to fly.
The Piper Cub
Lab Mod 1 – Slide 23
What airplane represents the stagnation point for Bi-Plane Design?
The Beech Staggerwing D-17
Lab Mod 1 – Slide 24
What is the distinctive feature of the Beech Staggerwing D-17?
The negative stagger of the wings. The top wing is further aft than the bottom.
Notes: The top wing was set back to accommodate stability requirements.
Lab Mod 1 – Slide 24
What was the main difference between aeronautical research in WWI vs. WWII?
WWI was characterized by experimentation of all types. By WWII, the final form of the prop-driven aircraft had crystallized. The emphasis was now placed on achieving higher performance with the standard design.
Lab Mod 1 – Slide 26 & 27
In order to accommodate the aircraft needs of the second world war, what was aeronautical research primarily focused on?
- Lighter weight
- stronger structures
- More powerful engines
- Detailed aerodynamic refinement
Lab Mod 1 – Slide 27
True or False
According to Loftin, “the use of NACA laminar flow airfoil sections has never resulted in any significant reduction in the drag as a result of the achievement of laminar flow.”
True
Lab Mod 1 – Slide 28
To accomodate high wing loading while maintaining low stall speeds, aerodynamic research center on _______.
High lift devices.
Lab Mod 1 – Slide 28
True or False
The leading edge flap was a German development and data was only made available after the war.
True
Lab Mod 1 – Slide 28
What are some reasons why the “ideal” zero-lift drag coefficient is not attainable in practice?
- Projections of outside items
- Roughness/unevenness of the surface
- Leakage of air through the structure
- Utilization of air for cooling purposes
Lab Mod 1 – Slide 29
True or False
During the development period of WWII, it was often the case that reductions in drag were more a function of good design rather than a different configuration.
True
Lab Mod 1 – Slide 29
What ultimately limits the use of propeller aircraft?
The compressibility limits when approaching and reaching the critical Mach number.
Lab Mod 1 – Slide 30
How do aircraft compressibility problems typically manifest themselves on airplanes?
- Limited speed
- Large changes in stability and trim characteristics
- Loss of control effectiveness
- Loss of propulsive efficiency
- Aircraft oscillation and general lack of control
Lab Mod 1 – Slide 30
What “flying qualities” did the 1941 NACA report suggest?
- Longitudional Stability/Control
- Lateral Stability/Control
- Stalling Characteristiics
Lab Mod 1 – Slide 32
What aircraft is commonly associated with the highest level of technical refinement ever achieved in a prop-driven fighter aircraft?
The P-51 mustang.
Lab Mod 1 – Slide 33
Who is credited for the design of the P-51 mustang?
Edgar Schmued
Lecture Notes
What WWII era aircraft had a speed higher than the P-51 Mustang?
The Dornier Do 335 Pfiel (tractor and push props)
Lab Mod 1 – Slide 36
True or False
New propeller-driven aircraft manufactured since 1945 have largely exceeded the capabilities of WWII-era craft.
False. New propeller-driven aircraft designed since WWII are of the same general layout, and their aerodynamic qualities have not greatly improved.
Lab Mod 1 – Slide 39
What is likely the most significant improvement to prop aircraft since WWII?
The supercharger for reciprocating engines and pressurized cabins.
Lab Mod 1 – Slide 39
What two aircraft hold the seaplane and land-based prop-driven speed records, respectively?
Seaplane = Macchi M.C.72
Land Based = F8F Bearcat Rare Bear
Lab Mod 1 – Slide 39
What two families of aircraft dominated passenger transport until jet transport became available?
The DC-6 and DC-7 and the Lockheed Constellation series.
Lab Mod 1 – Slide 40
The Lockheed L.1049G Super Constellation was known for what qualities?
- About 15% of total engine power was attributed to recycled exhaust velocity.
- “Probably” the lowest specific fuel consumption of any reciprocating aircraft engine.
Lab Mod 1 – Slide 41
What are the pros and cons of a turbo-prop vs regular reciprocating engine?
Per unit weight, the turboprop offers 2 to 3 times the shaft horsepower provided by a reciprocating engine but has a significantly higher specific fuel consumption.
Lab Mod 1 – Slide 41
What was the largest passenger-carrying turboprop aircraft to date?
The Tupolev Tu-114
Lab Mod 1 – Slide 42
In terms of executive aircraft, what aircraft is considered one of the most exceptional aircraft?
Piaggio P180 Avanti
Lab Mod 1 – Slide 43
The Piaggio P180 Avanti is known for what characteristics?
The Three surface configuration (TSC). This reduces the drag at any c.g. location.
Lab Mod 1 – Slide 43
What are the key performance parameters provided by Loftin?
Hint: There are 8
- Maximum Speed
- Stall Speed
- Wing Loading
- Maximum Lift coefficient
- Power Loading
- Zero lift drag coefficient
- Skin friction coefficient
- Maximum L/D
Lab Mod 1 – Slide 47
What are the three phases of aircraft design development?
- Conceptual Design
- Preliminary Design
- Detailed Design
Lab 2 – Slide 4
