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PocketGCC mirror

January 25, 2006 on 10:55 pm | In Announcements | No Comments

Today, I have setup a mirror for PocketGCC files, mainly for the users of the PocketGCC yahoo group, but its available for everyone to use. You can get it HERE.

I think there are a lot of files that need to be added, and hope to also add a good amount of documentation files to the mirror, such as howtos and tutorials.

If you have any file that you think would benefit PocketGCC users, please drop me an email at geek at iraqigeek dot com with a description of what you have, and how you think it would benefit the PocketGCC community.

EDITED ON 03/02/2010: The mirror used Philer which doesn’t seem to work on my new host. I’ve pulled that package offline and instead created a 7z file with all the PocketGCC related files I have and updated the link above to point to it.

Some ideas about RC planes

January 22, 2006 on 6:49 pm | In Technology | 4 Comments

I’ve always been a big fan of aviation, and always wanted to learn to fly RC planes, and even build a few of my own, but living in Iraq during the embargo years didn’t help much in fulfilling this dream.

Anyways, I’ve been reading and following RC groups around the net for quite some time, and though I still haven’t flown an RC plane, I think I’ve learn quite a lot from reading all the forums around the net.

One of the topics that are often discussed is long endurance RC planes, especially within the UAV (unmanned aerial vehicles) communities and how to achieve this. Most of the discussion usually revolves around using composite materials in building the air frame, or how to improve fuel consumption and engine efficiency, and sometimes (very rare) someone thinks about hybrid RC planes but without having any clear idea on how to do this.

So, here are some of the ideas that I’ve had across the years:

First, I want to talk about hybrids. When thinking about a hybrid, most people tend to use the same analogy for cars, which is using the gas powered engine to charge a set of batteries that are later used to power an electric motor that in turn drives the car. This usually works in cars because cars don’t usually utilize the power provided by these engines to its full extent, and spend a considerable amount of time idling in traffic jams. This analogy falls apart with airplanes since they are bound by physics laws and have to keep moving above a particular minimum speed. So, what kind of hybrid solution can be used?

Well, my idea is about using solar cells to provide electric power. I think it has already been proven that its possible to fly a glider using solar power alone, at least during day, and have a gas powered engine kick in only when the plane requires extra thrust, say during climb. Even if those solar cells don’t provide enough power to drive a propeller, they can still be used to provide power to run the flight electronics and servos, and even drive a relatively high power video (and/or telemetry) link for many hours.

Integrating solar power in an RC plane, even with not so efficient cells, doesn’t add a lot of weight. There are many (extremely) light weight, and flexible solar cells being sold around the net for very reasonable prices, that will not add much weight to the RC plane. If you consider the weight saving from requiring having less battery packs on board, there is a good chance that there won’t be any increase in weight at all. You would still need to have some battery packs on board to provide for backup and insure stable operation, but no big packs would have to be carried on board.

Next in line, there is engine efficiency. There has been a lot of talk about how 4-stroke engines are more fuel efficient, and how fuel injection, electronic ignition, and using smaller carburetors can dramatically reduce fuel consumption, so there’s not much to talk about here.

One, simplistic, way to increase flight time is to simply carry more fuel. The way I am thinking about achieving this is by designing a wet-wing, aka using the wing structure as a fuel tank. While this is no new idea in real planes (even small Cessna planes use wet-wings), I still have to see someone implement this in an RC plane. Some of the advantages of using a wet-wing design include increased available space in the plane haul, relatively lighter and possibly smaller haul design since the weight of the fuel will be carried inside the wings. Other benefits include less strain on the area where the body of the plane attaches to the wings, since the body will be considerably lighter.

The major hurdle, and the reason I think no one has done this on an RC plane, is that it’s not really easy to seal the wing structure against leaks while still maintaining the flexibility and light weight of the (dry) wing. Another reason is that in building such a wing, you need to thoroughly consider the materials that will be used in the construction of the wings, since the fuel can be corrosive against many materials.

Considering the huge advances in composite materials, and how they are being increasingly used in the construction of RC planes, such as carbon fiber, epoxy, Kevlar, and Teflon, I believe its has become more feasible to build such a wing. It will still require a considerable amount of engineering work in making casts for the custom wing molds, but I believe it’s doable.

Another idea that I’ve been thinking about, though I don’t know if it works or not, is using part of the thrust generated by the propeller as a sort of a super charger (or turbo charger if you want), to increase the amount of air that is going to the engine, and hence increase the total power generated by the engine. Of course we are talking about internal combustion engines here. In a very simplistic way, this can be achieved by using an adapter to increase the area of the carburetor air intake, hence catching more of the air flow generated by the propeller. Again, I don’t know if this will provide any significant increase in power, or if it will provide any increase at all, but I think it’s not that hard to experiment with to find out.

Of course, one could integrate ideas and build a wet-wing and have the top surface of the wing covered with solar cells. It will be quite a feat to do that, but I think the outcome, if properly engineered, would be quite remarkable.

I guess that’s about it for this post. I have a lot of other ideas for UAVs, dealing with automatic route planning, maintaining constant low ground altitude (while avoiding crashing), terrain following, and laser guidance, but I think that I would be getting myself in a good amount of troubles by discussing those topics anywhere online, especially if such topics are raised by an Iraqi guy. I already get enough hostile comments from many people around the net just because of where I come from. I guess there are a lot of ignorant people out there who truly believe that ignorance is indeed a bliss, but what can you do about that?

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