# How can I estimate the minimum runway needed to take off with a hang glider?

New Alexandria
• How can I estimate the minimum runway needed to take off with a hang glider? New Alexandria

I'm interested in short, or trick, take-offs - such as from platforms, tall trees, etc.

I think that I should have

This will let me add to my intuition from regular launches (from sites with known-good launch conditions), and estimate how much velocity I need to add via a run / push.

The methodology to count the wind measure seem a bit more grey, right now.

I can have a sense of the wind where I am, but it may quickly change beyond my launch site. Since I'm considering how to launch from a stationary position, it would be good to feed my senses / calculations more data like this.

• What you need is enough lift to remain in the air. For that, the maximum lift of your hang glider needs to exceed the total weight.

When you know the total weight of the glider (you included), you can derive the theoretical minimum airspeed from the lift formula:

$$L_{max}=\frac12{\rho}V^2C_{max}S$$ $$V_{min}=\sqrt{\frac{2W}{{\rho}C_{max}S}}$$

Where:

• $L$ = lift
• $\rho$ = air density
• $V$ = air speed
• $C_{max}$ = maximum lift coefficient
• $S$ = wing surface
• $W$ = weight

Now you have to know your maximum lift coefficient. Suppose this is 1.2, and for safety and initial manoeuvring, let's add a margin of 40% to the weight.

Let's say your mass is 85 kg, and the glider has a mass of 35 kg. The total weight would be 120 kg — that is about 1,177N weight, which for the sake of safety margin is increased to 1,650N.

I'll estimate the surface of the wing to be $16m^2$. Assume a normal day, the air density will be about $1.225kg/m^3$.

Filling in the numbers is the formula:

$$V_{min}=\sqrt{\frac{2\times1,650}{1.225\times1.2\times16}}$$

Any wind speed you get you can subtract from this figure: what is left you have to achieve by pushing, running or diving.

Tags
• I'm interested in short, or trick, take-offs - such as from platforms, tall trees, etc. I think that I should have a wind speed and direction measure an understanding of my wing surface area This will let me add to my intuition from regular launches (from sites with known-good launch conditions), and estimate how much velocity I need to add via a run / push. The methodology to count the wind measure seem a bit more grey, right now. I can have a sense of the wind where I am, but it may quickly change beyond my launch site. Since I'm considering how to launch from a stationary

• Here are a few thoughts: 'Real' accidents happen much too seldom to be of any real measure, and they would have to be compensated for the number of passenger kilometers as well to be objective. Large airlines may have be involved in more accidents, but they have more aircraft. Many airlines low down on the reports had accidents many years ago. Avherald and the like may be good sources but emphasize that they don't report on all accidents. Different jurisdictions have different reporting requirements. What is a fair and unbiased method of measuring airline safety?

• The alpha vane is an external probe used to measure the angle of attack. I have been trying to understand how exactly it works, but I can't find any clear explanation or simulation. Is the vane static or dynamic i.e. does it rotate along its central axis? Given that it has a significant surface area, I think that it would either: Rotate because of the force/drag exerted by the airflow, and give an angle of attack proportional or equal to its angle of rotation Measure the force being exerted on it via a force sensor embedded in the surface Is either of these correct? In short, how

• Let's say I call up Wx and have the wind direction and I know the runway headings from my charts and the pattern is empty. I can do the math, but it's tedious and slow and even worse when there are multiple runways. This is what I usually do: Runways are 13 and 31 Wind is 253° which rounds to 25 $25-13=12$ $31-25=6$ I'm going to use Runway 31 Is there a trick to determine best runway quickly without doing the math?

• It's easy to go online and look at prices of a Cessna 172, but what are some examples of how to breakdown the real world costs of ownership? how much other maintenance should you plan for? How much does an engine overhaul cost? Insurance hangar etc.. It would be great to also get some typical costs and ranges, since some element are more predictable than others. Obviously the costs will vary based on individual aircraft and location, as well as over time, but I'm looking for information that would help someone make the buy/rent decision. Prices can also vary geographically. I'm asking

• I'm a student pursuing a US Private Pilot License, and recently scheduled my checkride. I've been training in a 1981 Piper Warrior (PA-28-161), but if its annual goes sour I may have to take my club's 1980 Piper Archer (PA-28-181). I have well over §61.109's 40 hours in the Warrior alone, and only ~10 hours in the Archer. I have a separate club checkout and CFI solo endorsement for each... the box is really for. Of course I'd rather test in my more-experienced plane, but I'm asking specifically for regulations here if Plan A falls through. Are there any regulations or headaches that I

• In a full motion Level C or D simulator like those used by the airlines and for jet type ratings: How should a pilot log the simulator time in their logbook? I.e. Can you log: Total Time Instrument Time Time in Type Cross Country Time Night Time Landings (including night landings) Dual given/received Anything else?

• Many larger airports (class Bravos) have a landing fee. What's the process for assessing and collecting the fees? How do these landing fees work with general aviation aircraft? Where can I find out what the fee will be? Is it published? How will I be charged the fee? (Pay before leaving the airport, bill sent to my home, etc.) Is the landing fee a flat rate or is it calculated based on aircraft... for a scenic flight. He lives very close to a moderately busy class B airport while my home airport and FBO is over an hour away from him. I offer to fly into the class B airport to pick him up

• Where can I find nice flutter animations/videos (other than YouTube) to add to a presentation without violating Copyright regulations ? It can either be for wings as well as blade arrays. Are you aware of any OpenSource database on this topic ?

• translate to a deflection of the surfaces, mimicking the "old" mechanical control setup. It is my understanding that this is the design choice of Boeing in its new aircrafts. I do not wish to discuss how Airbus and Boeing made their design decisions, but rather see if there has been performed a study on what interface is preferred by pilots, eventually differentiating among private/commercial pilots...Provided an aircraft with a fly-by-wire system, there are basically two possible choices when it comes deciding how to let the pilots interface with it: rate control / attitude hold: a deflection

Data information