Hot answers tagged

49

Mass doesn't affect the maximum distance, only the maximum endurance. For example, image two identical planes A and B: A weights 50kg less than B. Assuming no wind (horizontal / vertical) and speed of best glide, both gliders will land at the exact same spot. The lighter airplane A however will arrive later than B, as the speed of best glide is less than ...


42

All airplanes can glide, if they couldn't they wouldn't be able to fly in the first place. When you glide an aircraft you are converting height into airspeed, which you can use to move across the ground. How far you can go across the ground for height lost is called the glide ratio for the aircraft. Gliders have a very high glide ratio as their wings are ...


36

A glider and a paper airplane operate on the same principle: Exchanging whatever potential energy (altitude) they have for the kinetic energy (airspeed) required to keep air moving over the wings so they produce lift, giving a stable, controlled descent (glide). In both cases the airfoil will not stall unless it exceeds its critical angle of attack which is ...


33

All airplanes can glide. Some glide better than others. A very old reference I read talked about engine-out landings in military aircraft. Their procedure was arrive at the airfield at X feet, circle once and land. Trainers like the T-33 needed 2,500 feet, other aircraft needed 3,500-5,000 feet. An F-104, which is basically an engine with fins, needed 20,...


33

The number one emergency in a glider is a tow rope break at low altitude, less than 200 feet above the ground with no appreciable headwind. Below 200 feet, the proper technique is to land straight ahead, which usually means landing off airport. Between 200ft and 500ft, it is possible to make a U-turn back to the runway, and land in the opposite direction ...


33

With basic instruments (altimeter, speed and climb indicator and compass): Forget it! A glider can enter a cloud when thermalling into it from below. Below the cloud the rising air was governed by dry adiabatic laws. Once it crosses into the cloud, the air is fully saturated and humidity starts to condense - after all, this is how clouds form. Now the ...


32

Yes, it is normal. With very rare exceptions, gliders are not allowed to operate in IMC (instrument Meteorological Conditions) and must remain clear of clouds. There are also powered aircraft that do not have attitude indicators, mostly for the same reason (VFR, Visual Flight Rules only).


30

Yes learn both, but... not at the same time. As Dave says, there are too many differences to be absorbing simultaneously. It's like a new airline pilot taking a type course on a Dash 8 and an RJ at the same time. It'll burn you out. If all this is a hobby activity in the first place with no urgent time lines, drop the power training for now and go take a ...


29

White is indeed chosen for thermal reasons. Gliders use epoxy resins which cure at room temperature and are then tempered at 60°C. This tempering shifts the glass transition temperature to something close to the tempering temperature, so the structure must not be heated under stress to more than this temperature. To limit heating by solar radiation, black ...


27

No. A (pure) glider cannot make a go-around in the way a powered machine can. The glide path can be influenced by airbrakes, flaps, chutes or slipping, but mostly those are for reducing your L/D, i.e. steepening the approach (you win again, gravity!). Gaining height without updraft is only possible by converting kinetic energy (speed), and that gain is ...


27

I'm aware that under zero power it is a glider, but there are gliders that sustain flight and have enough lift to climb etc. This statement is a bit incorrect. Gliders don't climb like aircraft as they are constantly falling to the ground unless they catch a thermal, wave lift or ridge lift, in which case they can ride the updraft to gain altitude. In ...


26

Yes, all aircraft have a glide ratio. On many of the higher-performance fighters, it's 1:1 at best (1 foot altitude traded for one foot forward gliding). Many of the newer fighter aircraft are intentionally unstable. They aren't really flown by the pilot; they're flown by a Flight Control Computer System (FLCCS) which depends on electrical and hydraulic ...


25

Thankfully, I never had to make this choice. In my training I learned to stay in the plane and flare at the height of the treetops, then let the plane sink into the branches and have them stop and suspend the aircraft. The fuselage is quite effective as a protective shell, and up on top the branches are thin and flexible. Use the parachute only to hoist ...


25

To expand on Quiet Flyer's answer, it's technical and economic at the same time. Technical: Winch is limiting because you are deposited in the same spot over the field, whereas a tow, if the pilot knows what he's doing, can take you to a thermal up to a few miles from the field. Plus you can get towed higher. If you had to choose the launch method that ...


24

Many modern gliders only have one wheel -- two is a great luxury! In a glider the wing and flight controls remain effective until the aircraft is almost completely stopped - with a little training and practice it's possible to balance on the one (or two) wheels right up to the point where you're nearly stopped, at which point the glider will gently tip onto ...


24

Yes, it is safe. Well, there is a reason why the stick travels as far as it does. One is the restriction in long-term maximum stick forces of 15 N (see §22.143(b) in the linked PDF), which is easier to fulfil if the stick has more travel. The other is the required roll speed to switch from +45° roll angle to -45° roll angle within 5 seconds for a glider ...


24

Gliders, as every other aircraft, are susceptible to bird strikes. This is a detached glider's tail after hitting a 10 kg vulture: The accident was caused when the crew lost control of the airplane following the loss of a part of the tail assembly after the vertical stabilizer on the airplane struck a griffon vulture head-on. Some ...


23

I am not a glider pilot, but the principle holds for flying any fixed wing aircraft1: you should keep your head level with the aircraft, as you described, not the horizon. As your instructor explained, there may come—or will come—a time when you are not able to keep your head level with the horizon due to the nature of a particular maneuver or orientation, ...


23

If you ever get the chance, do try a winch start in a glider. It is, to say the least, an interesting experience. I do not believe it would be accepted by the general public. So, that is one more reason, it would scare the paying passengers.


22

Yes, the yaw string on the canopy of a glider is there to show you whether or not you are coordinated, especially during turns. It indicates the relative wind, so will be straight unless the glider is slipping or skidding, in which case it will swing to the left or right. For those not familiar with them, here is an image that shows one: According to ...


22

In addition to the other answers, let´s look at this L/D(=E) diagram of the enticing DG-1000 from DG Flugzeugbau (but fear not, 'tis true for all gliders) : The best L/D ratio is equal for different wing loadings, but is occuring at different speeds - the higher the load, the higher speed. You can also see that the minimum/stall speed is also higher for ...


22

Here are some options for flying in an environmentally friendly way: Use an electric trainer: Since last year the all electric trainer aircraft Pipistrel Alpha Electro has FAA certification. Assuming the batteries are charged with renewable energy, this would mean no greenhouse gas emissions at all (excluding manufacturing). It will probably still take some ...


21

I won't prove it's not possible, but I'd would be surprised it is. I'll develop the reasons why and provide the physical framework you can use to compute a solution to have, with some effort, a final answer. The glider case cannot be scaled up to an airliner It works with a glider for two reasons: The height to be reached before the glider is able to gain ...


20

No, a glider can't make a go around, but if they are going fast enough they can make a low pass (which looks like a go around), but that generally means that they won't be in a position to actually land even if they wanted to. The key to safely managing and landing a glider is energy management. When coming in to land it can't be too slow and low OR too ...


20

With current technology the L/D might go up to 70 or 75, and going higher would require an almost impractically large wing span. Gliders need to fly in tight circles to use updrafts, and the larger the wingspan becomes, the bigger the speed difference between inner and outer wing will be. Also, landing such a wide wing without dropping a wingtip will be very ...


19

There are very small jets that for hype-related reasons are called wingsuits. As current jet technology (and propeller technology) is easily capable of producing (from a human-portable frame) enough thrust to lift itself and a human-sized load, there is no obstacle to creating a true powered wingsuit. The reaction surfaces are very small in relation to the ...


19

As an ex-hang-glider pilot... Two other answers have covered the basic concept of gliding - namely that you're constantly descending, and to stay aloft you need to be in air that's rising faster than you're descending. Early hang gliders and paragliders had no problems staying up in normal ridge lift with glide ratios of 7ish:1. Before that, they were just ...


19

As pointed out by Juan's answer, they are not required for the kind of operations allowed for gliders, so they are left out for cost reasons. Furthermore, artificial horizons are relatively complex and expensive instruments, at least in contrast with most other instruments you see in a glider cockpit. Older models need to keep their gyroscopes running in ...


18

You're correct -- they're speedbrakes, often referred to as spoilers, and are retracted when striving for efficient flight, but are generally extended in the landing pattern so that you have correction available if you start to get slightly low. Also frequently extended when the glider is left on the ground to reduce the effect of gusty winds & the ...


18

Perlan II will climb to extreme altitudes on wave lift, not thermal lift. Wave lift is created when strong winds blow approximately perpendicular to a mountain range, and the wind speed increases steadily with altitude. This creates a standing wave in the atmosphere, kind of like the ripple behind a rock in a fast moving stream of water. On the leading edge ...


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