Originally Posted by
jester_s1
On a project like this, you can waste a lot of time testing things that aren't really a big deal. Engineers are like that; they want to cover every possibility and do testing on every little thing to determine for themselves what they like the best. Good engineers learn from the past experiences of others and trust it so they can spend their time on the answers that no one has figured out yet. You guys have some major issues with your airframe design, so worry about that. We're telling you how the two gears behave, so listen to us. You're talking about a substantial structural change to go from trike to taildragger, so you're going to probably wind up with another airframe revision just for that. Set it up as a trike and give it a wide stance so it rolls well. The best ground handling model I've ever flown is my Kaos, so have a look at the wheel width and get close to that. A close second is my Ugly Stick which does happen to be a taildragger. One issue though that none of us regular RC pilots have to deal with though is that you're going to abuse your front wheel a lot. A Fultz nose gear would be a very good idea, and make your firewall nice and beefy with some good reinforcement. Nose wheels on models are notorious for bending and tearing out firewalls when models are landed on the nose, and I imagine that's about the same amount of stress you're going to be putting on yours.
They have given us 6 months to waste on a plane that can be build in 2 weekends. This is because they want us to go through the engineering process and test and document everything. A big part of this project is that 60 page detailed design report. All the testing we have been doing will end up in there and it will greatly improve our score if we can justify decisions made on the plane through testing.
I do believe that getting a top spot at this years competition requires to focus on many things that are not a big deal individual but together make a big difference in the score. Shaving off even 1 ounce could make as much as 10 point increase in the final score. If the pilot can do the same with conventional or tricycle landing gear but one saves 2-3 ounces - thats a big deal. If both weigh the same then we will figure out which one he is more comfortable with.
Looking the the
Kaos models, I can see that the configuration provides a lot of stability because 2 of the wheels are mounted on the wings. That definitely works for low wing planes but the structure is much different on a high wing design like ours. Why not convert to low wing? There are addition obstacles on the taxi mission that make it very difficult if the wing cannot clear over them.
In my honest opinion, I think conventional landing gear will be better. When looking at stability, the tail wheel being far from the CG, will make it impossible for the plane to tip forward or backward when going over the bumps. In the tricycle configuration, all 3 wheels are relatively close to each other and stability would suffer. When looking at weight, I will have to add an extra servo and everything that goes with it to control the front landing gear when I can get away with using a tail servo to do both on conventional landing gear.
As for control I don't think that a single front wheel would perform better than steering with a back wheel. Someone brought up that its better to control object with front steering like cars. Cars have been around for a long time and it has become standard to use front steering, so it must be better? I think cars have front steering to avoid accidents and make it much easier for the driver. If a driver keeps turning it will be easier to see the position of his front end rather than his rear when driving forward. Boats have a rudder at the back end and planes also have a rudder at the end when in the air.
From a historical standpoint, 80%-90% of bush planes have conventional landing gear. There must be a reason for this.
Even despite all of my information of stability, control and past data, the RC community keeps pushing me to use tricycle landing gear. I cant ignore that, so I need to test it out to figure out whats best. The taxi mission plays a huge role in the competition. If we fail that, we instantly lose 80% of our score so any time wasted with configurations is not really time being wasted. I have over 10 members on my team, I might as well come up with tasks for everyone. To me its very fun to test out different stuff and thats one of the main reasons I am part of this project.