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# Questions tagged [vtol]

For questions about vehicles capable of vertical take-off and landing.

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### what is Limit load factor structural and aerodynamic envelope at structural design gross weight and maximum gross weight?

As an aerospace engineer, as soon as I saw the words "structural and aerodynamic envelope" the first thing that popped into my mind that is it V-n diagram? But when I searched about it in ...
87 views

### How the power gained from exhaust of an engine is calculated?

Ryan XV-5 Vertifan used exhaust gas from engine to rotate the fan inside the wing. If I want to design an aircraft using this propulsion system how can I calculate how much power I can get from a ...
140 views

### Why does the V-Bat not counter-rotate?

V-Bat is a VTOL aircraft built by a company called Martin UAV. It seems to have a single pusher propeller. But then why does it not counter-rotate to balance the rotation of the propeller? Any clear ...
2k views

### How much thrust is lost through a curved exhaust nozzle?

In modern VTOL aircraft energy is usually directed through nozzles to achieve vertical lift. How much energy is lost when changing the direction of flow in static thrust conditions?
1 vote
219 views

### What is the major difference between this VTOL setup and an actual helicopter, in terms of degree of freedom?

I am studying QNET VTOL(Vertical Take off & Landing) system. I want to know how it is different from an actual helicopter . According to my understanding, an actual helicopter has 6 degrees of ...
723 views

### Why do F-35B jets hover with their weapons bay doors partially open?

This is an interesting phenomenon noted for F-35B aircraft during vertical flight and vertical landing. They will do so with their weapons bay doors partially opened. ...
10k views

### How does the F-35B not flip over during transition?

As the engine nozzle rotates, the lift-fan cannot. Wouldn't this imbalance of moments around the center of gravity result in the F-35 pitching up onto its back? As can be seen at 5:14 in this video: ...
237 views

### What is the decrease in power when a drone is in descent?

For a quad-copter, or a fixed-wing drone with quad-rotor formation, how much would the power of the motor decrease when a constant speed descent is needed to bring the drone back to the ground? Does ...
157 views

### If I put two ductfans behind one another, would I got the sum of the rated thrust or other thrust values?

I am trying to design a VTOL system for a drone and I don't want to have extending motor arms that make it look like a quadcopter. I want to use duct fans and thrust vectoring nozzles. However, the ...
267 views

### How does the Urbanaero flying car move forward?

From the pictures of UrbanAero flying car: https://www.urbanaero.com/cityhawk, I can see that can achieve VTOL using the two propeller in front of and in the back of the passenger compartments. ...
3k views

### Could a plane land vertically in a strong headwind?

I know there are VTOL craft meant to take off and land with a vertical trajectory. But, under the perfect wind conditions, could a normal airplane ever land (safely) with a vertical or nearly vertical ...
755 views

### How a takeoff decision point(TDP) for vertical takeoff vehicle is defined?

For a vertical takeoff vehicle like a helicopter, how the takeoff decision point is defined or computed? Look at the snapshot below, seems the height of TDP is related to the rejected takeoff distance?...
394 views

### Can you have a Hybrid Turboprop-Jet engine?

To start things off I am writing this to gain information for vehicles in a story, so I am more so looking for theoretical possibilities, unless there are real world examples. The background and my ...
5k views

### Why do VTOL aircraft (F-35 or Harrier) have only one engine?

Why do VTOL aircraft (F-35 or Harrier) have only one engine? Is it because it is simpler and less expensive? Or what are the reasons?
641 views

### Why does Harrier have split hot exhaust nozzles?

This is a repost after the original questions were deemed too complicated. Hawker Sea Hawk shot by Smudge 9000 under CC-SA 2.0 licence. Harriers seem to inherit elements from Sea Hawk, that the ...
1 vote
203 views

### I need some help to understand the rationales behind some STOVL jet designs, especially the Pegasus-Harrier configuration [closed]

In the question:Why do VTOL aircraft (F-35 or Harrier) have only one engine? Aeroailas answered why mature STOVL fighter designs only use one main engine, but did not answer why there are no mature ...
18k views

### Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?

As I understood from this article, wings on an airplane basically create lift by pushing air down. Maintaining the lift force expends energy because air needs to be continually accelerated downwards. ...
1 vote
88 views

### Can a normally poorly handling airframe with high moments of inertia actually have superior flight dynamics under autonomous control? [closed]

I’m not a pilot but know a thing or two about flight dynamics. As you know there are currently quite a few aircraft under development designed for low-and-slow and (eventually) autonomous flight. ...
596 views

### Did any VTOL aircraft implement an airfoil with engine-blown exhaust?

Did any VTOL aircraft implement an airfoil with engine-blown exhaust?
1 vote
2k views

### What would be the Sref i.e. Reference Wing Area for Drag Build Up Calculation in case of a box wing design?

Would Sref be sum of areas of both, the front and the back wing? or just one wing? Assuming both the wings have equal areas (image below) Details - So, I am calculating drag using the component drag ...
94 views

### The cost of maintaining VTOL devices

Which device for VTOL flight costs the most to maintain for a given number of flight hours? A tiltwing mechanism? A 2D thrust-vectoring nozzle (vectoring only between VTOL position and cruise ...
1k views

### How to calculate lift and drag coeffecients for VTOL aircraft in the takeoff stage?

How would I calculate CL and CD for a VTOL aircraft while it is in it's takeoff/landing stage? The particular aircraft is a fixed wing/quadcopter hybrid so I know that I can treat this as a thin ...
781 views

### Why is the F-35B's elevator not in neutral position when in vertical flight mode?

I was watching videos of F-35B taking off and landing vertically on ships when I realized that when transitioning from horizontal to vertical flight mode (I don't know the exact vocabulary to describe ...
241 views

### Would this quadrilateral-shaped airfoil produce lift with a zero angle of attack?

I have been recently studying the shapes and characteristics of different high-lift airfoils that have been used for VTOL aircrafts. While studying these different designs today, a particular ...
1 vote
2k views

### How do STOVL and V/STOL aircraft differ?

Wikipedia's page for STOVL begins with A short take-off and vertical landing aircraft (STOVL aircraft) is a fixed-wing aircraft that is able to take off from a short runway (or take off vertically ...
223 views

### How do I calculate the total cruise power from the propellers accounting for the losses?

Let's say I have an aircraft with four propellers (see diagram below) and I am supposed to calculate the cruise power required to drive the aircraft forward. The wing creates the lift and propellers ...
104 views

### How to use a set of Pressure Transducer to mimic pitot static tube for VTOL vertical airspeed indicator?

May i know if i have 3 pressure transducer, 1 facing upwards and the other downwards to measure the vertical velocity of a VTOL (Vertical Takeoff and Landing aircraft) and another 1 on the nose of the ...
474 views

### What is the typical procedure if an engine fails during a vertical takeoff?

My understanding of VTOL aircraft (correct me if I am mistaken) is that the plane accelerates vertically until it's a bit off the ground, at which point the thrust is slowly vectored horizontally, and ...
2k views

### What are the disadvantages of a Tail providing lift? (tandem-wings included)

Most aircraft feature the tailplane configuration, which requires the main wing to provide higher lift than the weight of the plane itself, what seems counterproductive. Few aircraft have featured ...
813 views

### Which prop location creates more lift? Leading edge or blown flap?

Which prop creates more lift? Leading edge or blown flap? In distributed propulsion there seem to be 3 prop locations: leading edge (NASA X57, blackfly), blown flap (Lillium), and pusher prop (...
205 views

### XFY-1 Vertical take-off mechanics

Hi I saw this video the other day of an XFY-1 doing a vertical take-off and landing and moving left to right while hovering. See the video Here. After watching this I had a few questions on how ...
103 views

### Questions regarding VTOL and VMU inhibits [closed]

I have been working on a game which has futuristic VTOL-capable air and aerospace crafts. A player recently wrote that the stall warning (tone and aural) and AoA (tone and visual) were distracting/...
296 views

### Is a chambered fan more efficient than a ducted fan?

A chambered fan is not exposed to the oncoming airflow in forward flight. I am working on a VTOL design that uses a chambered fan. There will be a wing attached to top of the thrust arms. Could it ...
825 views

### Would this hybrid impeller design create enough thrust for a VTOL aircraft?

I am wondering if combining a centrifugal blower impeller with an Archimedes screw impeller would create a hybrid impeller that would create enough thrust to lift up a VTOL aircraft. Please reference ...
21k views

### Can you identify this fighter aircraft?

If someone can identify this aircraft, please tell me which aircraft this is?
556 views

### Why does the US Marine Corps fly the Harrier, a VTOL or operationally STOVL aircraft?

The UK flies the Harrier because they have STOBAR carriers, but why does the United States Marine Corps fly the Harrier?
836 views

### Why aren't tilting propellers used as an alternative for ailerons or elevators?

I was wondering what are the reasons for not using tilted propellers fixed to ailerons/elevators/elevons? Or even on wings with no control surfaces at all? Wouldn't the 2nd way of thrust vectoring ...
826 views

### What is the current state of regulation regarding VTOL aircraft in the LSA category?

With quite a few concept designs in progress, I am curious what the current FAA regulations are regarding vertical takeoff and landing vehicles in the light sport aircraft category.
1 vote
1k views

### Disadvantages of using thrust vectoring only in an aircraft with variable rotation nacelles such as the X-19

Take a quad tilt rotor aircraft such as the curtiss-wright X-19 or even a bi-tilt aircraft such as the V-22. What would be the advantages or disadvantages of using thrust vectoring only for control ...
446 views

### What are the commercial benefits of VTOL? [closed]

there are a lot of companies doing R&D on VTOL aircraft. I understand their necessity for the military, but for civilian aviation, there are a very few application that requires it( medevac, ...
1 vote
165 views

### About F-35 hover/ roll posts responsiveness [closed]

how responsive is the f35 in hover. especially in the roll axis. What do think of the roll posts? is it a good concept?
292 views

### Could wing tilting be a mechanism for VTOL and high angle of attack for jetliners? [closed]

My question is about turbofan airliners, could an airplane tilt its wings 90 degrees so that the fuselage horizontal axis is perpendicular to the longitudinal axis of the turbo fan. This way an ...
833 views

### During VTOL landings, do Harrier pilots cut power before touching the ground?

When vertically landing, do Harrier pilots cut power before they touch the ground?
373 views

### Are there planes that can fly without wings? How would a plane be able to fly without wings? [duplicate]

Are there any planes that can fly without wings? How do they produce lift? How do they control the attitude?
2k views

### How to calculate the power required during transition from VTOL to fixed wing?

In a VTOL, I have calculated the power required for take off and cruise which was not difficult at all. Between take off and cruise, there is a phase where the VTOL has to transition by tilting the ...
477 views

### Does the Lilium VTOL wings produces lift during takeoff?

I just had a look on some of the recent development in the personal VTOL electrical aircrafts. I am wondering if the Lilium VTOL wings produces lift during takeoff? I would expect a quit high wind ...
1 vote
128 views

### What's the smallest 3-blade propeller for this motor? [closed]

I've got a 15470 brushless 35kw motor from China How do I find the smallest 3-blade propeller I can use for this motor? Here are it's specs, Max Power: 35KW Max Amp: 400A Max RPM: 8500 Max Volt: 120v ...
84 views

### How are rotorcraft and/or VTOL aircraft handled once they get to an airport? [duplicate]

I am asking this from an ATC perspective ... my experience as a pilot is that they would make helicopters fly the same approach but once they got the airport environment in site where do they go? Taxi ...