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Model Lightweight RC Plane

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Electric power is one option as already discussed. Besides batteries, super-capacitors (e.g, 1F caps) are commonly used to supply power. The obstacles to solar power are just too great for most modelers.

Other options for portable power include compressed gases, particularly carbon dioxide, and rubber bands. Rubber bands may sound old fashioned, but I believe the world record for indoor flight with them is on the order of an hour or more. Of course, for such performance, the entire model weights only a few grams and uses exotic materials for the structure.

This being an electronics forum, however, the OP may want to consider the alternative of capacitors for powering an electric model. John
 
Thunderchild said:
haha that can't work the generator drag will be higher than the prop power as it is not 100 % efficient and if it were nothing would happen anyway because they would balance


That wasn't the idea at all... If the motor isn't running off the battery, and the prop is still spinning the motor while the plane glides, some power must be generated, even just a small amount, why not make some use of it by storing it back to the battery. Solar panels alone most likely won't run the motor contuiously for flight, nor keep the batteries charged for an endless flight. Just thinking of ways to extend flight time.

The prop and motor are already there, the drag will be the same.
 
ah I thought he meant another motor and prop acting as a permanent generator. anyhow the idea is still not that feasible because with those little brush motors and I should think any motor and generator the generation or rather the use of the power generated will cause resistance - enough to stop it turning, I reversed a toy car motor one of those kidi things that run on 6 volts with a 2-4 amp motor the children can drive around in it. well I got hold of one that was slung out and tried to reverse it as a generator man that took some elbow grease to turn, if just turned no problem but if I gave it a load like a lamp it became quite a beast to turn
 
HarveyH42 said:
If the motor isn't running off the battery, and the prop is still spinning the motor while the plane glides, some power must be generated, even just a small amount, why not make some use of it by storing it back to the battery. The prop and motor are already there, the drag will be the same.

Current technology for model gliders allows the prop to fold, so it doesn't produce much drag compared to one that is not folded. The configuration of a battery-powered motor with folding-prop and a glider that can use gravity and solar power (i.e., thermals) has proved to be the most efficient. The free-wheeling prop, even if it produces some electrical energy is so inefficient and drag producing that flight times are reduced compared to a simple glider and folding prop, even if one ignores thermals. Add in thermals, and flight times can be very long. John
 
Yes John,
Change the definition of "Solar Power" to be the heating power of the sun on the land which creates rising currents of warm air. Thermals. They can power a glider all day long. Steer the glider to where the hawks are circling in a Thermal.:D
 
i will b meetin my team members probably tmrw..will keep u guys posted..been lookin at some sites for aircraft modelers too...this is gonna b a hard job..besides im talkin abt 2000 AUSTRALIAN DOLLARS...they said the maximum they'll giv us is tht amount..to reduce weight, instead of having elevators,ailerons and everything, cant we steer the aircraft by havin 2 props and then varying the speed of them?for landin we decrease both..im wonderin whether sombody suggested this already..thanks for all the help guys..will keep u all posted on any developments..
 
yes I suggested the dual prop steering but thats off the top of my head I can't guarantee anything.

I did have a thought though after taking a look at some small solar panels that I have, they are boards with little elements (each making about 0.5 volts) stuck to them, the actual solar elements that make up the necesary of the pannel probably weigh about 1/4 to 1/3 of the total panel weight so consider that in selecting pannels, you may be able to remove the single elements and embed them more easily into the wings etc.
 
yes..tht is a good idea..but due to the nature of the project, we hav to b careful in ensuring tht the aerodynamics are not affected also right?
 
NYE,

You have to think like a bird.( a long distance traveler like a Canada Goose.).
Steering with props? Great. Battery to get plane up? Also good. If you want to squeeze more out, think of this.
Once your plane is in the air, get it as far up as the battery will take it. Now shut motors down, and glide for let's say 30 seconds, and restart motors to climb again. Just like that. So like a bird, get in the air, save energy by gliding and restart the cycle again.

Have fun.
 
Let me toss out a few of things to consider in your meeting. Using differential power to steer and to control altitude is a proven method. Model Aviation (March, 1997, page27) had a very nice design called RC Turbo Sport. A couple of us built them. They were capable of flying outdoors on a calm day, but any wind made them almost impossible to control, even by experienced RC pilots. Is there an experienced pilot in your group? The motors and radio equipment for the RC Turbo Sport are still being sold by a small company that sells them incorporated into ligtweight blimps and the like. The only name I have is S.G. Corporation, ElCajon, California 92020. Cost (1997)for a complete model, motors, and radio was $20USD. I have seen similar ads in more recent magazines. The cost seemed reasonable, but I didn't pay any more attention to them than that. BTW, Model Aviation is the publication of the Academy of Model Aeronautics (AMA), which is the major USA model avaition organization.

My personal view is that control by differential power is still a novelty and is very difficult to get the hang of. The weight of the extra motor and prop exceeds the weight of light-weight servos and other methods of control, such as, heated wires, to say nothing of the effects on drag and duration. From experience, I can tell you that controlling a polyhedral airplane with a single control (rudder only) is far easier than using differential power.

If you can express your design goals more concretely, I am sure many on this group will have much more to add. One thing you need to define is whether you want an airplane capable of flying outdoors and in what wind conditions? Will soaring (e.g., engine off flight) be allowed. What level of control do you need? Are there targets for weight, duration, load, or speed? Are there limits on wingspan and chord?

Good luck. John
 
Do you have a link to the contest rules. Please post them if not.

jpanhalt said:
My personal view is that control by differential power is still a novelty and is very difficult to get the hang of. The weight of the extra motor and prop exceeds the weight of light-weight servos and other methods of control, such as, heated wires, to say nothing of the effects on drag and duration. From experience, I can tell you that controlling a polyhedral airplane with a single control (rudder only) is far easier than using differential power.
I agree.

You need to figure out if the solar cells + motor + prop will provide enough thrust to overcome the weight/drag they will impart on the airplane. As I said earlier. If not, use a small motor/prop and only enough cells to turn the prop. The propulsion system is there only to conform to the rules. You will be entering a glider. Another advantage is that you machine will fly nearly as well on a cloudy day as in bright sunshine.
 
Use a pretty powerful brushless motor and lithium battery to propel your glider high enough then drop them by a parachute because they are too heavy for the glider to carry around.
Then have a tiny motor from a pager's vibrator powered by a tiny solar cell from a calculator. The motor will spin a small propeller and will look like it is doing something.
 
hey guys..sorry for the long delay...we might go in for a solar powered airship sort of device..it will basically be a huge wing filled with helium..hope it works and our supervisor approves of it...
 
nye said:
hey guys..sorry for the long delay...we might go in for a solar powered airship sort of device..it will basically be a huge wing filled with helium..hope it works and our supervisor approves of it...

A wing by its nature has a large surface area to volumn ratio.
Helium has a lifting force of 1 gram per liter. [SIZE=-1][/SIZE]

Helium has so little lift this may be a waste of time.

Sorry.


[SIZE=-1] [/SIZE]
 
You could do a blimp, but to have solar cells on it it'd have to be very large.
 
if it will be airtight as I suppose it will what about vacuuming it ? nothing is lighter than nothing at all but still air (the atmosphere in which the wing must fly) is 1g per litre so you have to make sure that there are more litres of vacuum than there are grammes to the whole project could be tricky, easier to make an airbaloon frankly or an airship
 
A vacuum inside the wings? Then the wings must be made of steel or heavy glass because of the 15 pounds per square inch pressure and it will fly like a brick.

How would you control the bouyancy of a helium balloon? It is rising too quickly so dump some helium. It is dropping too quickly so dump some passengers.:D
 
we've abandoned the helium idea..we were thinkin of goin for an airship, but then our supervisor told tht its hard to control them...can somebody tell me where i can find the schematics or components for a circuit tht will track the plane??as in say for example a laser or dish will always be 'in line of sight' withh the plane...cos we might hav a series of reflective dishes along the lfight path, with the capapbility to track the plane, and re-direct the sunlight on to it...plus..wht's the maximum range of radio remote control???
 
Common RC transmitter/receivers are 3/4 watt, range is pretty much line of site (if you can see it to control it you're fine) about a mile. Tracking the plane itself is probably harder than the rest of the project together.
 
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