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R/C 'Copter on Mars!

#1
It's beginning to look like the Mars 2020 rover will be carrying its own R/C 'copter to the Red Planet. I can't wait to see this in action. Or to see who will be the first one here to create their own model of this machine! ;)

"However, perhaps the most innovative payload for Mars 2020 is the Mars Helicopter Scout (MHS), a solar powered helicopter drone that would enable an extended range of visual observations of the surrounding terrain as well as identification of potential up-close investigative targets of interest." From nasaspaceflight.com's article.

The amount of autonomy required by this aircraft is amazing. Most 'copter flyers here on Earth would have trouble flying with a half-second latency. Because of the long distances, radio signals take anywhere from 5 minutes to 10's of minutes to make the 1-way trip between the planets. Thus, this 'copter will have to fly under 100% autonomous control.



http://www.ainonline.com/aviation-news/aerospace/2016-06-23/nasa-helicopter-could-fly-mars

https://www.nasaspaceflight.com/2016/10/mars-2020-rover-eyesight-skycrane-landing/
 

PsyBorg

Wake up! Time to fly!
#2
I have to question the validity of flight based on earth proven principles. Is the air dense enough for a propped craft to create lift? Is gravity less or more there? Knowing our battery tech and solar use can they get viable flight times. Can the rover replace a broken prop?

Kudos to the dudes who managed to scam up 15 million dollars in grants to fly RC though. That's one hell of a sponsorship. :applause:
 
#3
I think if they are smart enough to get stuff there they are probably smart enough to figure out flight requirements in the Mars atmosphere. That will be one hell of a walk of shame when it crashes. lol
 
#4
From the nasaspaceflight article,

The MHS would be capable of flying for no more than three minutes per day and cover a distance of only 1 km (0.62 miles) daily
This craft weights 1kg and has a 1 meter rotor span. On mars, that weight will be equivalent to about 0.38 kg on earth. Manned helicopters have been up to 42,500ft on earth, and mars atmosphere is more like 60-80k feet. This will be a record breaking craft by any means, but it does sound within the realm of possibility. That said, it will have a very short flight time, but sounds like it flies pretty fast.
 

Craftydan

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#5
Honestly, I'd think the 0.006 ATM pressure would be the big hurdle for flying thingamabobers on Mars.

Most people see the CO2 or cold and think that's why the place is unlivable, but to put this into perspective, that's roughly equivalent to an altitude of 84km or 275,000'. This is one of the big reasons for the skycrane instead of a parachute -- you need reaction mass to kill all of the delta-V, since there simply isn't even enough atmosphere there to slow a descending lander via parachute.

So far the world record for Helicopter altitude is in the low 40k' (looks like someone recently beat it by a few thousand feet, but I can't find anything more official than the pilot's blog and an un-cited Wikipedia blurb), where the air is roughly 30 times thicker. Airbreather fixed wing have gotten *ALMOST* this high (a MiG-25M back in '77) (Edit: Correction -- almost *HALF* as high). A few drones have also hit around this altitude. Rocket planes have gotten higher, but all of these airframes have pushed to the coffin-corner to get there -- extreme speed, right at stall for that altitude.

Granted, each of these airframes had to not only maintain lift at target altitude, but they had to carry enough fuel to get there, so not having to climb out of the gravity well is an advantage . . . but this whirly bird is solar powered? Another 1/2AU out? I'm curious to see how this widget pans out, and I do wish them the best, but you can color me skeptical.
 
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PsyBorg

Wake up! Time to fly!
#6
Like I said. Them dudes got a 15 mil sponsorship to fly RC. As far as them being smart enough to get there and being smart enough to fly once they are there.... I seen too many govt studies for the most useless of things get approved. I'm with Dan on this one.

Skeptical dog.jpg
 
#7
It would surely be record breaking. They say it would only fly 3min/day which means the battery is extremely small. Altitude limits for manned aircraft are also slightly different then what is possible using unmanned systems. By any measure though this would be a record breaking feat. I had a professor in school that worked on a martian glider for a mars mission. They even did glide tests at 60k ft altitude with a balloon drop and the thing broke the sound barrier. Aerodynamic flying machines do work on mars. The reason they use rockets instead of parachutes or wings for rover entry decent and landing (EDL) is because of the huge amount of energy involved. The NASA mars glider project wasn't ultimately selected because it couldn't land, and thus was a suicide mission. They only have so much mass allowance on each trip.
 

Craftydan

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#8
Aerodynamic flying machines do work on mars.
When they do, I'll be happy to agree with you. Until then . . . we'll see.

This has yet to be accomplished using any traditional technique that works here, short of what works in space already. Even the sound breaking test you mention (see coffin-corner) happened at 4.5 times lower equivalent altitude at 12 times thicker air. Reducing the needed lift by 2/3 isn't as strong of an advantage as it sounds, with the gas that will generate it being so crazy thin. My point with the parachute (which have been used, but that landing was rough enough to deploy the airbags ;) ) is the forces that will drag an airframe to a stop from extreme speed are the same forces that will keep an airframe aloft. Neither project is impossible but while the tests have been promising, the science is extrapolated and unproven.

1kg of mass allowance is still CRAZY expensive, but over the entire 830kg of the lander, and the popularity of flying autonomous toys (NASA/ESA are PR organizations, after all), I can see them ear-marking a single kilogram on a "even if it doesn't work it will look cool" moon-shot-like project.

We've still got about 4 years before the design is packed away and sent skyward . . . and then the long drift in the deep dark. Until then, we'll see.
 
#9
You don't have to be exactly at an equivalent altitude to have a valid test. The glider that flew was scaled to provide equivilant performance at an achievable altitude. Look up scaling by non dimensional numbers if you are not familiar with aerodynamically scale engineering test articles. The numbers must indicate that it is possible, or they wouldn't have gotten the money. That said, it is still an extremely ambitious project.
 

Craftydan

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#10
Yeah, I've done scaling before. A lot of scaling. It's the black art of the engineering world and the heart of good hard science. Where the dominant modeled factors remain dominant, it's amazingly useful -- I use it all the time around here when re-sizing poorly-spec'ed gear off the cuff . . . but unproven is still unproven.

It doesn't have to be in those conditions to be valid, but the farther away from it gets, the more faith is put in the assumption that "model = reality" -- that assumption can have some rather nasty consequences when you move the science to an engineered product. Dropping a scale parachute into a pressurized wind chamber is a fair proving ground with the proper scaling, but if you've seen the video's of it the tests, the engineers going in were sweating bullets.

As Psy mentioned, I too have seen sufficiently convincing proposals which promised amazing results for next to nothing pass governmental scrutiny -- $15M is pocket change compared to the mass allowance cost, after all -- but that being said, I don't think we're looking at another Theranos project . . . but will the back-of-the-envelope calculations that got the $15M or the extra study and testing they squirreled away from the production (and profit) margins pan out? I hope so . . . but we'll see.
 
#11
In this video from JPL, they show some tests inside a vacuum chamber with pressures reduced to that of Mars. Clearly, they have at least that real-world experience to draw on.


So, while I think some serious challenges are in store, I'm not quite as skeptical as Dan. The idea may not be mature enough to constitute a primary mission objective, but it's certainly a valid item to include as a technology demonstration.

Remember, the air bag landings seemed pretty audacious at first (one item to note -- the parachutes slowed the lander quite a bit, but retro-rockets slowed it to a stop about 30 meters above the surface, where the airbag-encased lander was dropped to fall/bounce to a stop). Then, the Curiosity "sky-crane" seemed especially challenging. Yet, both of those methods proved themselves worthy.

I have a great deal of faith in the JPL gang -- I think this stands a good chance of working.
 
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#12
As Crafty Dan said vacuum chamber and lab tests don't guarantee a system will work, but that video is extremely promising. That vacuum chamber test is done in earth gravity... Crazy stuff does often work. We don't have to assume it doesn't work until proven otherwise. If everyone thought like that we wouldn't have crazy stuff like the rocket boosters that can land themselves that Blue Origin and Spacex have. The sky crane idea is still crazy in my book... just a crazy risky thing that works.

It will be interesting to see what comes of this project.
 
#13
For the vacuum chamber test done in Earth gravity, they only need reduce the weight of the craft appropriately (probably by removing the batteries/computer and controlling it through wires). Of course, that will change the balance and inertia, but there's no other way of doing these tests (short of loading a vacuum chamber on an aircraft and flying a 3/8 g parabola). In all, $15M seems pretty cheap for this sophisticated of a tech demo.

Keep in mind that I'm no engineer -- simply a recovering meteorologist. But the principles seem sound to me. I think the greatest challenge will be in the electronic "smarts" to control it. This thing will have to set down with near-zero horizontal velocity in order to avoid tipping over.
 
#14
I do happen to hold an engineering degree, and it looks like a fun project. From the video, the smarts and control system are where it is at. It looks like many a first flight for a new pilot even tipping over on a flat surface. Machine vision and ranging is probably one of the larger costs. My senior year, I helped with image processing on a team that made a robot play chess. That was a very simple machine vision implementation, but the hardest part was coping with lighting variations and other environmental factors. I agree, $15M is not a bad price.

Many people can't appreciate the difficulty of designing a craft when almost the whole process has to be done in CAD and simulations. We are talking about a team doing months of number crunching and creating a series of tests that involve making models from extremely expensive materials tested in multi million dollar equipment.
 
#15
Computer models are most certainly a useful tool in the engineering process... with the caveat that those models MUST be verified and validated by rigorous testing. And there are many such engineering models whose predictions have been repeatedly proven to represent reality, especially in the aerodynamic world.

Take, for instance, the Space Shuttle. Although many of its components had been tested in real-world conditions (the engines had been run for full duration burns, the orbiter had been carried aloft and dropped for glide tests, wind tunnel tests at hypersonic speeds, etc.), the entire system had NEVER been flown (outside of computer simulations) before two brave souls climbed aboard for its first mission (that, I pray, will be the LAST time a spacecraft is ever launched on a first flight with a crew). And almost all of the model predictions of the Space Shuttle system's performance were proved accurate -- the vehicle performed almost entirely as expected throughout the many different environments and flight envelopes in which it operated.

The Martian surface pressure is about 6-7 millibars -- equivalent to conditions in our atmosphere at just over 100,000 feet. Tests of both powered and unpowered aircraft actually have been flown up to at least 98,000' in recent years, so the thought of aircraft actually working in the Martian atmosphere is well beyond simple speculation. Furthermore, wind tunnel tests using Mars conditions have also proven out these concepts.

In the near future, actual glider tests are planned where the aircraft is carried aloft to above 120,000' and then released -- these tests will certainly provide additional data points to either confirm or improve the model predictions.

Thus, I have great faith that the aerodynamic aspects of these aircraft are well understood, and pose little challenge compared to the software side of the house.
 

PsyBorg

Wake up! Time to fly!
#16
They may have a promising start but as we all know in the multi rotor world durability is always an issue. They not only have to get past the whole aeronautic issues they have to contemplate an conquer ecological ones as well. Heat and cold being the one enemy of electronics. High revving motors are going to produce heat that when added to the extreme low temperatures on mars will be problematic as we all know what happens to metal that gets put thru that kind of change. We also know plastics get very brittle with extreme cold. Carbon fiber is strong but I don't know what it would be like in that kind of cold. Anything done for temperature management is usually heavy and we know weight will be this things bane.

Next is power systems. We know the rovers have done well on the large solar panels they were designed with. I have seen pictures where the dust is covering a good portion of those. That tiny one they believe they can recharge with will get the same way over a much shorter period of time so that will be another major hurdle to overcome.

Bottom line the flight aspects may be easier to over come then other just as important issues like the few I have come up with off the top of my head.
 
#17
Personally I believe in engineering and technology. If they could get the drone to Mars then they sure as hell can calculate the lift that's needed to get it flying under the harsh conditions of Mars.
They are rocket scientists after all :)
 

PsyBorg

Wake up! Time to fly!
#18
Rockets HAVE to be aerodynamic.. We fly over powered bricks. Those two thought trains CAN'T ride the same rails on any planet that I can think of.

Can they do it... probably. Will they do it.. not in my life time. Question is cost and need. They can accomplish flight better in low G using a fish pump and jets to push it around with puffs of air more efficiently then with a motor driven air frame imo.
 

Munk

Unabashed Builder
#20
Having worked around the types of tools used for the analysis on these types of projects, I'd have to say I'd go with the engineers on this one. It's amazing to what depth real world situations can be simulated nowadays, and it only improves year by year. Real world tests are in every way still needed for proper validation, and it seems that they have some promising results with what they are working with.

Will it fail? Maybe, but my money's on the guys with two degrees staying up past four in the morning just to make sure the board traces are wide enough to provide the proper amount of convective cooling. That kind of iterative testing is what JPL is known and loved for, and whether or not they fail, I'm excited to see what comes of it :D