Model Lightweight RC Plane

No helium?
What is in an airship to keep it up? A big fire inside a hot-air balloon?

Hydrogen =)

not goin for the airship now..goin for the plane....

A brick flies pretty well if it has enough speed.

*smacks Audioguru with a carp*

The reality is here that solar cells are not going to produce enough power for propulsion at ANY stage of flight. There probably isn't even going to be enough to power the receiver and/or servos. Without "cheating" like has been suggested, you're going to have to convince the powers that be to let you use batteries charged from ground based energy sources like a small wind generator. You'll need batteries that can dump a large amount of current in a short time like ni-cads or even a pseudocapacitor. Either way weight will be a big issue.

As requested by others several posts ago, can the OP give more detail about the contest rules or a link to where they can be found? We seem to be flying in circles without them.
John

The rules allow a push at the beginning of the flight.
So make a rocket and put the plane into orbit.

The winning plane stays up for the longest time. A plane in orbit will stay up for weeks.

Yeah, for that reason alone I think the glider is the best way to go.

lol..sorry guys..its actually not a contest..its a uni project, and only our group is doin the solar flyer..but our grades depend on it!!!!!!we have a project supervisor, and basically wht's needed is a plane tht has the capapbility to be in the air indefinitely for ANY amount of time.therefore solar seems our only option.he wants us to devise a system such tht there is enough juice in the batteries to run it during the day and night..the project description tells us tht we can use a brushless DC motor and a Li-Po battery to provide the boost, but these are only guidelines..not rules..basically we have to work things out..only rule is tht it has to run on alternate energy..we were thinkin of having several receiver dishes tht will direct the sunlight onto the bottom of the plane, which will b comvered with solar panels..but the problem is the tracking system which is complicatd.so we might have to settle for the solar covered plane..flying wings are supposed to b hard to control right???.also i like to know of efficient and long distance control systems for RC planes.is going for computer based control too ambitious??

oh..and i forgot...it should b able to carry a payload of sensors, or u know..a useful payload..in the description they have indicated tht our plane could b used as a communcation relay post after a disaster, or have the ability to take images and map a certain area..basically the ability to do some useful stuff..pretyty hard isn;t it..and mind u, we're only 1st years!!!!!!!!!!!

oh..and i forgot...it should b able to carry a payload of sensors, or u know..a useful payload..in the description they have indicated tht our plane could b used as a communcation relay post after a disaster, or have the ability to take images and map a certain area..basically the ability to do some useful stuff..pretyty hard isn;t it..and mind u, we're only 1st years!!!!!!!!!!!and we hav a budget of about 2000 Aussie Dollars..but im sure all of it will go for solar panels...there are quite a few auto pilot and computer control modules available on the neet...is it good to use them?

Solar powerer aircraft are neither easy, small, nor inexpensive to build, but they can be built. Search on them.

A lead is: https://www.nasa.gov/centers/dryden/news/FactSheets/FS-054-DFRC.html

Contrary to your assumption about ease of control, a flying wing is not at all difficult to control. The Zagi series of models is a good example, to say nothing of the Northrup products for the military. The key to a flying wing is the airfoil, which will typically have a reflexed traiing edge compared to an aircraft with a conventional elevator. The wing must have a pitching down moment when the angle of attack is increased, because there is no elevator to do that. John

Aren't you taught anything in your Uni?
You have an impossible project and you don't know anything about its basics such as aeronautics, model airplanes or electronics.

I hope you get a few marks for trying hard.

i know quite alot about electronics from my prev studies..AND WE ARE 1ST YEAR STUDENTS!!!!!!its sort of an inter-disciplinary project..3 of us from mechatronics and 3 from aeronautics...we get marks for tryin hard, and basically we gotta do research and find stuff..and we hav a supervisor..

What sort of charging circuit are you using?
What sort of motors,servos,remote control etc.are you using?
Would you like to post your own ideas or just get ours?

You seem to have some advanced courses there .
You need to contribute some to the collective.
Don't be shy.

Look here:
**broken link removed**
and here :https://www.rcgroups.com/forums/index.php
and type in solar power. There is alot of info on batteries, power systems, building and materials.
sam

*turns on announcer voice from Williams' Smash TV arcade game*

"GOOD LUCK... YOU'LL NEED IT!"

Seriously though, what you are attempting to do is going to be mind bogglingly difficult to pull off.

The story told of the Rutan Voyager is that the original concept and preliminary estimates of feasability (e.g., the amount fuel, duration of flight, airspeed) were done on a napkin (or envelope?) at dinner.

The OP has enough information at this time to make preliminary estimates of feasibility. I would suggest starting with the power source and finding out how many watts per unit area can be produced and weight per watt they can expect with current technology photocells. For the airplane, there are good sources for estimating the wattage needed to fly a certain weight. Weights for the motor and batteries per watt or watt-hour, respectively, are also available.

Then, I would add a couple of recommendations: 1) It seems unlikely that one would be able to fly day and night under power using only the electrical energy gained during the day with currently available photocells. Thus, I would assume that during daylight, the aircraft could soar to conserve battery power. A reasonable assumption might be that the craft could soar no more than 1/2 of the time. 2) Wing loading for model sailplanes of up to 4 M span is generally limited to 10 to 20 oz/sq. ft., with larger models able to handle the higher loading better. Full-scale gliders (e.g., the Slingsby designs) have loadings of 4 to 6 lbs/ft.sq. with wingspans of 15 to 18 M. The relatively constant ratio of wing loading to wingspan, not area, is well known. If you assume a value of around 4 to 5 oz./ M span, a 2 M glider will fly with a loading of 8 to 10 oz./sq. ft.; an 18 M glider will support a loading of 90 oz./ ft. sq. Those are very rough estimates; just don't expect an airplane with a 10 M wing and 20lbs. /sq. ft. to soar very well.

Thus, you can find the power per pound available, the power per pound needed for powered flight, hours of sunlight, hours of powered flight needed, size and weight of batteries for night flying, and wingspan needed to be able to soar effectively. Then, all you need to do is design the airframe to meet those weight, size, and strength requirements. I would definitely suggest waiting for the Summer and going South, if possible.

As suggested above, don't be shy. Throw some of your estimates out for us to help you on. John