Fly to "space" . Solar plane plans a record.

[All Darc]

Well, space it's sometimes not a very used word. The guy who jung in a astronaut suit from a meteorological hellium balloon wasn't in space, otherwise the ballom would not work, since space it's suposed to be vacuum.



This plane intents not top "space" but to reach a record using solar cells:

https://insideevs.com/sunpower-solar...edge-of-space/






I supose it will be a record for propeller airplanes, since jet airplanes with few rockets added already reached such altitude.

[freebeard]

Electric jets with electric rockets?

[All Darc]

No, I refered about a rocket assistance added to combustion turbinel militar airplanes.

in the movie The Right Suff (1983) they showed a record attempt of CHuck Yeager, using a military airplane that had some rockets added to the back of the plane body. The the movie producers forgot to add the rockets to the plane used in the shooting.
But you can see when he activates the rockets in the controll panel of the plane.

Watch in 03:20 :

https://www.youtube.com/watch?v=ruEfQanG2Ww

This solar plane will not get even closer to that. It's a different record modality.

Originally Posted by freebeard

Electric jets with electric rockets?

[Piotrsko]

How are they getting past the humongous stall speed at altitude? Them wings will vibrate like a guitar string

[gone-ot]

Originally Posted by Piotrsko

How are they getting past the humongous stall speed at altitude? Them wings will vibrate like a guitar string

Get high enough (ie: edge of space) and there's neither air to fly on nor air to buffet the F-106 Starfighter's stubby wings.

[Piotrsko]

At those altitudes, the stall speed will not be significantly below the VNE, perhaps only a knot or two. tthere may nort be many air molecules, but they are moving awful fast. The major structural failure point is flutter of the control surfaces leading to flutter of the other surfaces. The F104 didn't have that problem because it was capable of mach + speeds. It had other issues especially near or at stall. The survivor sitting on a pole outside the test pilot school at Edwards AFB has a bunch of reaction rockets scattered around the fuselage to control the nasty stall/ tumble habits at apogee.

Col Payne has stories of his altitude records in a diamante of both almost freezing and controlling the glider at I believe 60,000 ft perhaps much higher.

[All Darc]

A bit of subject change.

Have you heard about a drone for Mars mission ?

On Mars, despite you get 1/3 of gravity, you have 1/100 of atmospheric pressure.
And sun's power, for sollar cells, it's 50% than on Earth.

But NASA will build a drone, mini helicopter, for Mars. Imagine the energy for blades rotation at 1/100 of air presure, despite 1/3 of gravity.

https://www.youtube.com/watch?v=2xSDBNzAtPs

Someone will say that if blades run faster in a air pressure way lower, the energy to move the air would, in theory, be the same. But the key point it's the loss due friction, much more relevant in this case.

[teoman]

Nasa does have very efficient solar panels. %40 if i remember correctly. You never get back the energy you invested to make them but for a mission to mars I suppose that is worth it.

I think they would also have very efficient and very expensive bearings too.

Using capacitors for the flight might be a good idea. They are not effected by the cold and have many more cycles than batteries.

[redpoint5]

Originally Posted by All Darc

A bit of subject change.

Have you heard about a drone for Mars mission ?

On Mars, despite you get 1/3 of gravity, you have 1/100 of atmospheric pressure.
And sun's power, for sollar cells, it's 50% than on Earth.

But NASA will build a drone, mini helicopter, for Mars. Imagine the energy for blades rotation at 1/100 of air presure, despite 1/3 of gravity.

Someone will say that if blades run faster in a air pressure way lower, the energy to move the air would, in theory, be the same. But the key point it's the loss due friction, much more relevant in this case.

I'll have to think about this one more, but a helicopter would be at more risk of "retreating blade stall" and advancing blade overspeed on Mars. The lower atmospheric pressure also lowers the speed of sound to a little over 500 MPH. Helicopter blades are not designed to approach the speed of sound. The advancing blade (blade traveling forward relative to the helicopter direction of travel) "sees" the speed of the blade tip plus the airspeed of the helicopter. The retreating blade (blade traveling backward relative to the helicopter direction of travel) "sees" the blade tip speed minus the airspeed of the helicopter. The side of the helicopter with the advancing blade has much greater lift (it's like a headwind on an airplane) than the retreating side (like a tailwind on an airplane).

You'd have to design the helicopter such that the advancing blade doesn't approach the relatively low speed of sound on Mars, while avoiding a retreating blade stall. This is probably accomplished by long blades.

Anyhow, I hope they do it since video/images are inspiring, even if the scientific value isn't as high as other experiments.

[All Darc]

The most efficient solar cell, mlti junction, do not reach 40% withou sun light concentration. If I remamber well the record of non concentrated photovoltaics it's 33% or so.

The problem it's also that the solar panel area, for this Mars drone project, it's too small.

The risk of damage, since it will fly by computer as even light speed took 3 minutes from Mars to Earth (6 minutes come and back), it's high. Any sand hiting the blades at such speed would be 30 times more strong in impact than a sand hitting a ordinary frone on Earth.

If the blade hit the ground, bye bye... Human can damage drones easily by landing mistakes. Computers even more. If they will take 800 million dollars in this project, they should put 3 or 4 drones in the probe, since it's too risk to send just one drone and find out it broked in the first day.

Originally Posted by teoman

Nasa does have very efficient solar panels. %40 if i remember correctly. You never get back the energy you invested to make them but for a mission to mars I suppose that is worth it.

I think they would also have very efficient and very expensive bearings too.

Using capacitors for the flight might be a good idea. They are not effected by the cold and have many more cycles than batteries.