Re: Autonomous airplane project

This project is apparently intended to be "quick and dirty" and cheap as
a lead-in to something else. It will not come down that way. My
experience is that for someone trying to start from scratch the initial
cost is going to be $1000.00 to have a plane-- any plane (well. . .
maybe not some of the toys or almost toys)-- on the field ready to take
off. You want something very special with about 3 to 5 times the flight
endurance of most R/C planes. Think $3000 to $5000 as a reasonable budget.
First, contact the guy at "RC Report" who writes the electric plane
column. Pete Young has a full-time day job teaching college students to
fly RC planes they design and build themselves. Grading is from very
serious requirements about how well the planes conform to specified
parameters. Pete is a professor in aeronautics and electronics at MIT.
He may know things that will help you with your effort.
Next, gasoline engines are much more fuel efficient than glow. You
should probably look at "Bruce Tharpe Engineering" and at his 'Giant
Flying King' with thought of using either a big electric motor or a
gasoline motor. This plane supposedly is easy to fly and will have a
lot of room inside for your experimental packages. Equip it with an
autopilot and maybe a GPS unit and it will be a lot safer (read: be able
to fly again) in the air and even find its way home. Both autopilots
and GPS units are readily available.
And, as mentioned by others, Find an experienced RC pilot above all to
fly it and teach you and your students to fly. Start up front by buying
and using a simulator. Flying a variety of aircraft on a computer
screen will be very enlightening in a lot of ways.
Reply to
Charlie
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I suppose you could say it is "quick and dirty" in a mechanical sense, but as I mentioned earlier this is primarily a comp eng project, so our emphasis is shifted away from mechanical and towards electrical. As far as cost and what can and can't be done, given previous discussion on the matter and research we've been doing we're hoping we can do quite a bit with under $1000. Note that our budget exceeds this, but we'd rather not put more than $500 of *easily broken* parts on a single plane. We may have to use a "toy" to accomplish that, but if a toy can carry our system and demonstrate autonomous flight then we're more than happy with it. I get the sense that the toy vs. not toy is a holy war among RC enthusiasts, and not very relevent to this project. We've all but settled on the electric EasyStar model; we're encouraged by the success that VR enthusiasts have had with it.
Thanks for the contact suggestion, we're always happy to have experts to turn to. It seems like there are some questions only experience can answer.
We currently have a GPS unit and a Co-pilot module, although we are optimistic about the plane's inherit stability making the latter unecessary. We're looking into black box modules that log flight data to aid in modeling the plane's in-flight behavior, after which we can apply the model to our control system.
Charlie wrote:
Reply to
NathanielC
On 30 Oct 2006 22:12:52 -0800, "NathanielC" wrote in :
I didn't intend it as an insult. "Proof of concept" is, in my book, synonymous. You want to show that your system can fly a plane safely and on a fixed course. Later on, if the proof-of-concept plane works, you can get into larger scale aircraft that can carry REAL scientific payloads. And that's really cool. I wish I lived closer to you guys. :o)
Sounds like a good test bed.
Later on you probably will want real-time telemetry and not just onboard black boxes. It adds a safety factor and can help in the search for a downed plane.
Marty -- The Big-8 hierarchies (comp, humanities, misc, news, rec, sci, soc, talk) are under new management. See
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Reply to
Martin X. Moleski, SJ
The concern that I am trying to express is that your choice of airframe will not begin to meet your needs because there might not be enough room inside.
Most trainers are about the same. The one I have is an old Hangar 9 "Cessna" ARF. That name means it is vaguely a generic light plane look-like with general Cessna color patterns. Span 60 inches, weight around 5 pounds, power Thunder Tiger Pro 46. Center fuselage outside measures nearly 4 inches wide and probably 5 inches high below the wing. There is no space left inside after the control package and protective foam is put in place.
A Google search says Taylor University is in Indiana. There must be dozens of R/C airplane clubs within a one to three hour drive. Do yourself a favor on a Saturday and/or Sunday when the winds are not too high and the temperatures are not too cold and go visit some of them. Look at their planes. Find an EasyStar either on a flight line or in a hobby shop and check it out.
Apologies: "Quick and dirty" is a term from vernacular. Not to be taken too literally. It means getting something done effectively and in a timely manner without a lot of formality. "Toy R/C Planes" in my references are just that. Try Wal Mart or Harbor Freight. The vast majority of the planes in the R/C fliers' universe are sophisticated and carefully tested miniature aircraft. The information and advice you are getting from other posters is from true world class national and international competitors and world class business people. I am awed.
My own best shot for low power consumption and space inside a plane would be a large electric sailplane. An available design might have a 4 to 6 inch cross section fuselage enlarged to perhaps 8 inches if needed to create a place for your electronic packages. Power is primarily atmospheric thermals with an electric motor to initially achieve a working altitude. Flight times can go on for longer than the pilot(s) can stand. I would like to leave a comment about winds up higher in your region, however. Someone I fly with has a cousin in Indiana who flys small electric foamies. So far two of them have gone too high and been picked up by those higher winds. Somewhere out there in the high sky, presumably, are two little lost airplanes unable to find their way back to earth. . .
Reply to
Charlie
| "Toy R/C Planes" in my references are just that. Try Wal Mart or | Harbor Freight. The vast majority of the planes in the R/C fliers' | universe are sophisticated and carefully tested miniature aircraft.
Ha!
| My own best shot for low power consumption and space inside a plane | would be a large electric sailplane.
I agree about the low power consumption -- sailplanes (another word for gliders) tend to be far more aerodynamic than other sorts of planes, and tend to have large aspect ratios, which means they need less power to stay aloft. (Yes, you can have an electric glider.)
The problem is that most gliders (electric or otherwise) have very little space inside, as the wider the fuselage is, the more drag it causes, and drag is the enemy. Granted, having a little wider fuse won't add much drag, but they tend to keep them very tight, often giving you barely enough room for only certain battery packs.
| An available design might have a 4 to 6 inch cross section fuselage | enlarged to perhaps 8 inches if needed to create a place for your | electronic packages.
Of course, if you want to enlarge your fuse, that means you'll be building your glider (or at least the fuse) yourself -- it's relatively difficult to widen the fuselage of an existing plane without ruining the structural strength and aerodynamics.
| Power is primarily atmospheric thermals with an electric motor to | initially achieve a working altitude.
... but finding thermals requires a signifigant amount of skill. (It's also fun!) People have made autonomous planes that take advantage of thermals and it's worked reasonably well, but it's probably not the way to go for the beginner.
But it has been done --
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(Really, this would be a relatively interesting project for programming your flight computer. You can either watch your airspeed and altitude for increases larger than you'd expect from just your motor alone, or look for increased air temperature outside the plane, and in either case when this happens you turn off the motor and start circling and see if you maintain or gain altitude.)
| Flight times can go on for longer than the pilot(s) can stand.
... or, until you're good at finding thermals, as long as your battery (for your motor) can stand, or if you're just using a high-start about 1-3 minutes each, or perhaps 30-60 seconds if it's a HLG (hand launch glider) :)
Learning to fly gliders (unpowered ones, anyways) gets you lots of launch and landing practice ...
| I would like to leave a comment about winds up higher in your region, | however. Someone I fly with has a cousin in Indiana who flys small | electric foamies. So far two of them have gone too high and been picked | up by those higher winds. Somewhere out there in the high sky, | presumably, are two little lost airplanes unable to find their way back | to earth. . .
The winds are indeed stronger up higher, but they're not generally *that* much stronger until you get to many thousands of feet up. What usually happens with a glider is that you find a good thermal, and you don't want to give it up, and your plane goes up and up and up until it's a speck in the sky, and then you glance away, and when you look back, you can't find your plane anymore. If you're smart, you then put your plane into a spin and hope to see it as it comes down (and some reflective tape on the wings helps a lot here) but many gliders have been lost this way (by flying too high to see.)
Contrary to popular belief, few people have flown so high that the sun has melted your glue joints, but flying into the sun IS a great way to not to be able to see your plane anymore!
It's rare that you hit sudden winds aloft that you can't even get your plane back because of them.
What happens with some small electrics, is that you hit a strong thermal and don't realize it until it's getting higher and higher, and then you lose sight of it like the larger gliders. Many people don't know to put them into a spin to help lose altitude and find them, and to make things worse, some of the park fliers with very limited controls are very difficult to make go into a spin, or can't even be made to dive fast enough to counteract the thermal. (And diving is dangerous too, as if you go too fast and then pull out, your wings tend to break.)
In one isn't familiar with the terms, `thermals' are just like the winds we're familiar with, but they're generally going up rather than to the side. There's a lot lot more that can be written about them, but I'm not going to dive into that subject here.
Reply to
Doug McLaren
On Thu, 2 Nov 2006 16:11:50 -0600, "wxfreqrs" wrote in :
Awesome!
It's a perfect application for the Honda 4-strokes. I'm not sure that anyone has worked out an oil system for aerobatic planes.
Marty -- The Big-8 hierarchies (comp, humanities, misc, news, rec, sci, soc, talk) are under new management. See
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Reply to
Martin X. Moleski, SJ
Just to get some closure to this one, here's our final shopping list for the project, heavily influenced by the 3 years of EasyStar discussion on the forums at rcgroups.com
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: EasyStar body: MPX4192 Hitec/Multiplex EasyStar ARF Electric RC Airplane ..... $ 59.90 (2 of these)
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Accessory Pack: MPX419AP Accessory Pack for EasyStar ..... $ 6.00
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Brushless motor: MM16154 Mega Brushless 400, 4 Turn ...... $ 94.90
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Lipo battery pack: TP420022 2S2P 4200 mAh "Pro Lite" 7.4V LiPoly Pack ..... $ 109.90 (3 of these)
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Prop: PE06040E 6x4E Thin Electric Prop ..... $ 2.80 (a half dozen of these)
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Motor controller: JESAP30W Jeti Advance PLUS 30 WITH Program Card ..... $ 79.90
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Battery charger: ETC2500 Li-Poly Smart Charger for 1-4 Cells ..... $ 49.70
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I think we're still missing motor leads, and we may get some NiCad batteries to use for test flights. Thanks again to everyone for all your help.
Reply to
NathanielC
On 4 Nov 2006 06:48:50 -0800, "NathanielC" wrote in :
That seems to me to add up to $403.10, although I didn't multiply $2.80 times 6 nor $109.90 by 3 because it wasn't clear whether these were unit prices or totals.
I personally wouldn't fool around with the NiCads. Learn the LiPo routine inside out from day one and have fun with them. They deliver more power per ounce and are going to teach you what you need to learn for future expansion of the project. See Red's Battery Clinic for more help:
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If you're thinking of NiCads so that you can have safer crashes, that's (in my view) the wrong approach. Get help from good RC pilots and develop good pilots on your staff. Build to fly, not to crash.
Let us know how it all turns out!
Marty -- The Big-8 hierarchies (comp, humanities, misc, news, rec, sci, soc, talk) are under new management. See
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Reply to
Martin X. Moleski, SJ

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