I assume
that following in the footsteps of the great tech pioneers it's made from paper. Can't figure out the rest of the acronym though.
Airbus has conducted a new test of a glider it thinks could one day fly on Mars. But Mars has such a thin atmosphere, we hear you ask, how could Bernoulli's Principle work in such a rarified gaseous environment? Airbus' Perlan 2 glider project is designed to address just such atmospheric problems, as it aims to create a …
I came to say the same thing, it looks very much like a Scaled Composites design - not just the windows, but the tail too (which has traditionally been a way to tell designer's work in aeronautical circles).
Edit:
Having looked it up, it appears that Bert Rutan was not involved, but it sure looks like one of his.
The original is not Rutan - it is Alvin and the other deep sea submersibles. Canopies stop being a realistic solution past a certain pressure differential, especially if you have aero (or hydro) dynamic requirements to contend with.
Checkered window pattern coctail:
1. Pressure differential of 1 bar (or more - for the submersible equivalent)
2. No pressure suits
3. Aerodynamics requirements
Shake with some coffee and serve to an engineer - you will get the same result in most cases.
Something like it would fly much closer to the ground on Mars, so any sensors would would not have to have as great a range.
This is very impressive. The U2 (which IIRC did switch off its engine to conserve fuel) managed 70 000, but both it and the SR71 pilots had full pressure suits to do so.
In truth the biggest issue I could see for a Mars glider is a) How do you fold it into the aeroshell and b)How do you deploy them at Mars?
On Mars, you'll apparently be expecting two pilots to do the job. That is feasible.
The biggest question for the moment is indeed how to get the plane to Mars. 1800 pounds of mass is within the limits of what a rocket can lift into orbit, but the bigger issue is the wingspan. 84 feet translates to around 25 meters, half of that is thus around 12 meters (taking the width of the fuselage into account). I don't have any figures on the length of the fuselage, but the available drawings seem to indicate that one wing is longer than the fuselage itself, so I'm taking wing length as principal constraint.
I don't think a rocket can house a 12-meter structure at its top safely. Maybe I'm wrong, but I think it would be better to have that plane as blueprints for the trip, and have it built locally with on-site materials.
Which, obviously, requires that the materials be available on Mars, which is probably not going to happen anytime this century, but hey, next century's colony will have a plane.
That's still cool.
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I always wondered about this whole "let's find the materials when we get there" thing. When you look at the amount of hardware and energy it takes to process any type of ore into a useable material, it seems hardly likely that it's more efficient to process the material there than to ship it over. In the case of aluminium alloys you'd need vehicles capable of mining the ore out of the ground, probably including explosives to break up rocks, then a crushing plant, then a separation plant, then a foundry, then some form of forming plant (rolling, forging, whatever) then machining hardware, plus the people and energy to make it all happen. Then you'd need life support for the months it would take to build all that, process what you need and then build whatever you actually set out to build in the first place. Seems extraordinarily wasteful unless you're going to need literally tonnes of whatever material you happen to need.
Sure Mark Watney and co were processing rocket fuel on site, but that was just a simple chemical reaction that was handled remotely with minimal hardware.
U2 switch engine off ? Myth. Flew at 60,000 engine with about 70 lbs thrust at altitude. Source : SkunkWorks, Ben Ritchie. SR71 about 85,000 max. Still classified ITIRC. After all, ruins of the West still like to pretend progress in Engineering is being made. According to rumour and innuendo, possibly well informed, is that this glider is the test bed to ensure designers are on right track for a Mars plane. A Mars plane will need to demonstrate flight at 100,00 feet. Perlan project originally were aiming at that height because it is a nice round figure. Utility as a Mars palne got Airbus and NASA interested, especially after Steve Fossets cumulo-granitis untimely death and reduction in funding.
That last 10,000 feet means serious aerodynamics and wing engineering as some airflow will have to go supersonic to keep plane airborne. Lookup "coffin corner" for the aerodynamic conundrum involved. If the designers succeed in getting Perlan II up to 100,000 feet, a Mars atmospheric vehicle is possible.
How such a machine could be delivered, assembled and launched is another matter. Noble project anyway. Go for it.
"That last 10,000 feet means serious aerodynamics and wing engineering as some airflow will have to go supersonic to keep plane airborne."
It depends. Mars gravity is only 1/3 G. So the aircraft will only need 1/3rd the lift of this test glider to fly on Mars.
But yes, if it will still have to go supersonic on Mars despite the low G then they've got some real design challenges ahead.
It would probably arrive in pieces.
The issue with getting to mars is about how to get moving towards mars and then how to stop moving towards mars. The first bit generally requires a really big engine and is fairly self evident. The second bit can be done either with a really big engine or by aerobraking i.e. by using the drag from the martian atmostphere to slow you down. Thus far (AFAIK) everything that has been thrown at mars has used aerobraking because it's a whole lot more efficient than lugging a big rocket plus fuel. As mentioned above, how do you then fit something that big behind a heat shield?
"This is very impressive. The U2 (which IIRC did switch off its engine to conserve fuel) managed 70 000, but both it and the SR71 pilots had full pressure suits to do so."
The pressure suits that Lockheed U-2 pilots wear doesn't give them much protection from the low pressure at 70,000 feet - the cockpit used to be pressurised to the equivalent of 29,000 feet, and even then some pilots experienced decompression sickness i.e. the bends when under a high workload (for example during tours over Afghanistan when long sorties were flown with not enough rest between one and the next.)
There have been several incidents when pilots have blacked out, become disorientated, or have forgotton how to operate the controls due to the effects of DCS and have come close to losing an aircraft, so the airframe of the U-2 fleet was updated in 2012 to allow a cockpit pressure equivalent of 15,000 feet to prevent any further occurrences.
Apart from efficient oxygen delivery, the primary funtion of the pressure suit is to make an ejection at 70,000 feet survivable (i.e. to prevent almost instant loss of consciousness and nasties like boiling bodily fluids.)
" The U2 (which IIRC did switch off its engine to conserve fuel) "
You're wrong on that score. The U2 spent virtually the entire mission in "coffin corner", so switching off the engine would have nasty consequences.
https://en.wikipedia.org/wiki/Coffin_corner_(aerodynamics)
Airbus is a name sponsor so gets its name appended to pretty mich everything the Perlan project does. Its not really an Airbus project though. They only provide (part of) the financial budget. Consistently calling it an airbus project is a disservice to a group of highly motivated volunteers imho.
Let's hope they don't get their units mixed up.
"No, in aeronautics you use USian measurements. Feet for altitude, pounds for thrust etc, etc"
Wrong,
In gliding, the units used are metric. (Probably something to do with the fact that gliding was developed as a sport mainly in Germany).
Competitive classes are distinguished by wingspan (13.5m, 15m, 18m, 20m, unlimited (also metric)) and MTOW (525, 600, 750, 850 kg). Instrumentation is very often (though not in the US), metric.
Good luck to the perlan group, but do not believe that anything Airbus but money is involved.
by the way: the goal of the project is to explore the upper reaches of mountain waves. So far the limits for these vertical air-movements have not been established in detail.
aviation metric ? err, no, not quite. So many Merkin built planes that Naval units are an Aviation international standard in much of the world. Knots, feet and so on. Europeans, especially those a bit further east are metric all way. Makes for a hard to read altimeter when the scale units are changed.
As for sponsorship, bit more to it than mere advertising. Have a look at Boeing 787 and 777-x wings. Compare to DG505 and similar. Modern glider wings are incredibly efficient, especially compared to other planes. As matériels science has improved, those same efficient airfoils and shapes are being used on the heavy stuff. Airbus and NASA are using it for what it is, a literal blue sky research project. Expect Airbus to consider an A3xx twin engine long long range design in 5 years if not already hidden in the designers offices.
One hopes Boeing are getting better at fiber structures though. Glider manufacturers have been at it since 1957 and I know of no composite gliders that develop cracks, unlike 787s.
From the Perlan website:
- Airbus is providing consulting on carbon fiber manufacturing quality.
- Airbus is providing the Perlan Project with critical consultations on aircraft and systems reliability.
So it appears that Airbus aren't making any parts themselves, but providing advice - and money.
Europeans, especially those a bit further east are metric all way. Makes for a hard to read altimeter when the scale units are changed.
Thought that was more in eastern block and eastward from there. Bugger if you're used to flight levels being roughly 100ft.
In gliding, the units used are metric. (Probably something to do with the fact that gliding was developed as a sport mainly in Germany).
Not true everywhere: the units used in gliding depend on where you are and its quite messy.
European gliding uses metric units.
In the USA they use feet, knots, nautical miles and pounds weight. Their airspeed indicators are upside down: zero at the top, cruising speeds at the bottom and some older aircraft still use mph rather than knots. I have no idea why they do this when speedometers in road vehicles are the right way up. Everywhere else I've flown the ASI has zero at the bottom and normal climbing and cruising speeds at the top.
In the UK its quite a mixture. Gliders airframes are metric for length, weight and wing area, instruments are ICAO (knots for speed and rate of climb, altitudes in feet), but distance is a mess. We use statute miles when talking to ATC but, because the badge scheme and racing tasks are metric, we think in kilometers for all cross-country flights and related distances.
BTW, until shortly after WW2, all European aircraft had metric instruments, but some time, in the 50s IIRC, all powered civil aircraft throughout the Western world adopted ICAO navigational units (knots, feet, statute miles) along along with their air traffic control systems.
The migration to SI units as internationally agreed in 1945, from that time on all non-SI units were considered 'alternative'. These alternatives were removed progressively and are entirely absent in the latest issue dated 2010.
http://www.icao.int/secretariat/PostalHistory/
annex_5_units_of_measurement_to_be_used_in_air_and_ground_operations.htm
{S} its a Challenge. Thats why Steve Fosset was original big sponsor. Perlan Project was originally a bunch of highly skilled glider pilots and builders aiming at a very difficult challenge. Still is but with bigger backing because a use for the cresults of the challenge is seen. Also the science knowledge gained when flying slow enough to directly observe upper atmosphere. Good enough for me.
>What on earth (or Mars) has that to do with how a wing works?
http://www.planeandpilotmag.com/article/bernoulli-or-newton-whos-right-about-lift/
http://users.df.uba.ar/sgil/physics_paper_doc/papers_phys/fluids/Bernoulli_Newton_lift.pdf
So yes, it has everything to do with how an air[o]foil works ... got my flame suit, hence icon ^, not pissed off, though ... ;-)
"So yes, it has everything to do with how an air[o]foil works"
Yes, and let's not forget that utter bullshit how "the air has to meet up at the trailing edge". It's clearly all Bernoulli's doing, all of it, as evidenced by the fact that a) no aircraft can keep flying upside down and b) no model aircraft has ever flown with wings made of a single FLAT sheet of material.
...oh wait...
well said sir. Utter bull the lot. Actual physics is simply Newtons Third Law. Air is displaced down, airfoil reacts buy going up. The airfoils shape influences its efficiency, as the Englishman Cayley demonstrated in 1809 ! Wings are just very energy efficient in doing it compared to using concentrated air displacement. eg, compare rotor wash from V22 Osprey with say, Sea Stallion. One blows Merkin 4WDs away, one throws up dust and small stones. A plane going overhead at same height barely makes a slight breeze.
It is not simply Newton's Third Law; if it was just down to Newton's Third Law then delta-winged aircraft, such as Concorde, wouldn't work. The downwash from an aerofoil occurs at the trailing edge of a wing which, in a delta-winged aircraft, is right at the rear of the aircraft, so if the lift came from downwash then it would produce a turning moment about the CoG/CoP, not a lifting moment through it. Furthermore, the direction of airflow over a wing isn't simply from the leading edge to the trailing edge but also along the wing to the wingtips, where quite a bit of energy is wasted in producing tip-vortices, hence the incorporation of winglets.
"if the lift came from downwash..." but it doesn't come from downwash, does it? Any object being pushed through the air with a positive aspect ratio will push the air it displaces down and forwards. The reaction is up (lift) and back (drag). The pressure differences at different parts of the wings surface are not the cause of the lift, they are a consequence of it.
"Any object being pushed through the air with a positive aspect ratio will push the air it displaces down and forwards."
I assume by "positive aspect ratio" you mean positive Angle of Attack (AoA), but the problem with this explanation is that, as the AoA increases, the lift vector would reduce and the drag vector would increase, and stalls due to upper airflow separation wouldn't be an issue because, in this explanation, all lift is generated below the wing. In practice though, both the lift & drag vectors increase with higher AoAs until upper flow separation leads to a stall and loss of lift.
It's also worth considering a non-symmetrical aerofoil with positive camber; such an aerofoil can have a completely flat lower surface but will still generate lift at zero AoA.
In reality its a combination of all the principles discussed. It's neither purely Newtons third law (Or asymmetric airfoils at 0 AoA should produce negative instead of positive lift forces and aerodynamic stall wouldn't be a problem) and its not purely Bernoulli's principle (as this wouldn't propely explain "barn door" wing lift and symmetric airfoil effects)
The real explanation is that it all depends on the specific speed, AoA, wing profile, air density, temperature, humidity, etc, etc. To really do it properly involves things like flowtubes, reynolds numbers, mach numbers, boundry layer effects and some other fun parts of physics that are hard to explain in text format.
> The downwash from an aerofoil occurs at the trailing edge of a wing
Bernoulli explains the pressure distribution around the wing, Newton explains why the plane doesn't fall out of the sky.
The 'downwash' exists all over and under the wing. As the pressure on the top surface drops, the air above that 'falls' down towards it. The higher pressure on the lower surface 'pushes' air away. The nett result is that air is accelerated downwards from slightly in front of the wing* to somewhat behind it. At the trailing edge the air continues to move downwards.
It is the _acceleration_ of the air from not moving to moving downwards that counters the acceleration that gravity applies to the aircraft.
* at trans-sonic and supersonic speeds it no longer does so in front of the wing.
Since the pilot is quite close to the viewports the view is not that bad from the videos and photographs I've seen. On top of that, at landing config (full landing flaps in the lower atmosphere) the attitude will probably be quite noticably nose down, giving a better view than you'd expect out the top viewports. That big central strut will limit vision a little bit but it shouldn't be too bad. A glider is VERY sensitive to crosswind so you're barely ever coming down onto the runway completely dead straight anyway.
I've read* that Red Mars book and it said they used airships on Mars.
I want my money back!
[*I say "read". I got about 3/4 the way through, before it started getting really boring and I gave up... just after the point were the author spent about 4 pages describing someone drawing circles on a piece of paper, whilst musing on the personalities of his companions]
Most modern 2 seaters and a lot of single seaters have a very reclined body position for the (front) pilot. This is not actually as bad as it seems, the seat is normally well molded to provide a body position that allows a comfortable position and enough support to keep the head up for looking out.
(See for instance this shot of a DG-300 pilot and not how he is positioned. Very reclined indeed. But from experience I can tell you that it's relatively comfortable. Sure you start getting a bit of a sore bum after a few hours but that happens in any glider (and usually even sooner in those where you are positioned more upright)
Most modern 2 seaters and a lot of single seaters have a very reclined body position for the (front) pilot. This is not actually as bad as it seems
It is when you try to do a high-AoA stall drill in a K21, and then realise you're a little *too* reclined...
I won't make that mistake again.
Vic.
I am sure it can fly. It can get up to the required INDICATED airpeed and fly about.
Tougher on landing or takeoff though. The actual speed over ground would be hundreds of miles per hour. So even if there were a 10 mile long runway on Mars, the tuchdown speed would be something like 600 mph.
Austin Meyer wrote about this long ago: http://www.x-plane.com/adventures/mars.html