Re: Crazy robot idea for this year 2
 

This would depend on the ref's interpretation of 'translative' contact with the bridge. The example given in the rule is that contact is translative through the robot, but another example would be translative through the balls.

Re: Crazy robot idea for this year 2
 

For rotary wing aircraft, you require much more power due to losses and inefficiencies.

Check this link out to see the differences in propellers and rotors:
http://www.heli-chair.com/aerodynamics_101.html

Theoretical thrust developed by common airplane engine - propeller combinations:
300 hp, 78" propeller develops 1,300 pounds of thrust
80 hp, 50" propeller develops 400 pounds of thrust
1.5 hp, 12" propeller develops 10.5 pounds of thrust

Theoretical lift developed by common helicopters:
300 hp, 30' rotor develops 3,400 pounds of lift
25 hp, 12' rotor develops 347 pounds of lift
2 hp, 6' rotor develops 39 pounds of lift

Re: Crazy robot idea for this year 2
 

I don't know about you, fox, but I ain't flyin' no fixed-wing aircraft controlled by the FRC control system in no FRC arena! No way, no how--there isn't enough room for anything that big without a ton of power--also known as a great way to drain batteries. It'd probably hit the wall before it got up to speed anyway. And if it did get up to speed, take off, and not hit the wall, I doubt it could turn fast enough to stay in the arena. That puts the crowd at risk. A helicopter has a much, much smaller takeoff area, and can be slower flying around.

Re: Crazy robot idea for this year 2
 

You completely missed the point of my post which was that you don't need to balance weight with thrust to get a vehicle to fly. A Helicopter relies on the same principles as an aircraft however the wings move above the craft rather than the craft moving through the air to generate lift.

And spinning blades are any better? Let me tell you a story now that we're on the safety train--

One time, bout 5 years ago at the RC flying field I am a member of, there was a gentleman tuning a new helicopter he had just built. This was a 0.30 cubic inch engine size heli, nothing big, bout 5lbs weight, with a rotor diameter of about 3 feet. While checking the rotor balance, he lost radio communication and the throttle was stuck wide open. Luckly the collective was in the neutral position so it just sat there on the ground at full power. Well this guy decides that the best thing to do is to reach under the blade and pull the fuel line off the engine. While he was pulling on the line to get it off the radio cut back in and the machine twitched. The sound was sickening- his arm was clipped by the rotor and broke it in three places. We rushed him to the nearby hospital and the resulting damage was so bad it requied 68 stitches, multiple reconstructive surgeries and he nearly lost the arm. This was after they cut off the leather coat he was wearing to get to the wound.

I would far prefer seeing fixed wing aircraft than rotary wing aircraft.

Re: Crazy robot idea for this year 2
 

I got the point of your post. I was pointing out that fixed-wing aircraft are entirely impractical for anything FRC-sized, forcing a helicopter to be the default choice.

Fixed-wing planes have spinning blades too. I've been at a field where in 2 years, 2 people lost or just about lost fingers to an airplane's prop. And that's while I was there--I don't know about any incidents that happened at other times.

If a chopper has a problem, it can reasonably be expected to go in one direction: straight down, as far as it can go. It's relatively easy to figure out that safety: don't get under it. If a fixed-wing bird has a problem, you have a glide slope--and that slope can change based on what happens while it's on that slope. Makes it much harder to dodge, especially with an arena-type setup.

However, neither of the two is as unsafe as both of them in a single package...

Re: Crazy robot idea for this year 2
 

That story sounds like a failure to include emergency shut-down hardware, a failure of patience to let the helicopter simply run out of fuel, and a failure of common sense to not realize how dangerous it was to reach near a spinning rotor.

I can see a similar thing happening with the prop of a fixed-wing RC airplane.

Re: Crazy robot idea for this year 2
 

Correct, but the danger zone with an aircraft is much smaller than with a heli.

If anything was permitted to fly it would have to take place in a similar fashion as the SAE aero competitions if FIRST expected to keep the same kind of hardware. If they were to take place in a FIRST-style venue, the field would have to be enclosed with netting or chainlink fencing (depending on the design limitations of the machines) and the hardware would have to changed sufficiently to make it practical to build aerovehicles which could fly in such a space. Perhaps a minibot style competition where the robot deploys a flying vehicle powered by a similar minibot or LiPo battery and controlled with an RC aircraft control system. You could even tether the vehicle to the robot and send it power/control from the victors mounted on the robot chassis. I think it would be awesome to have the craft fitted with an auto-stabilization system and have the CRIO track the craft using the camera and send it commands autonomously based on that positional feedback and the intended goal of the craft. A fixed wing vehicle could be launched quite easily with a mechanism. Indoor RC flight is a very common and prevalent hobby in Canada since nobody wants to stand in a field trying to fly a model with frozen fingers in the winter. There are piles of small helicopters and aircraft on the market designed for indoor flight.

This all said, the Mabuchi style motors are very common motors for RC aircraft and helicopters and are more than capable pieces of hardware.

Re: Crazy robot idea for this year 2
 

The SAE competition is where I heard about the guys losing fingers. (I didn't actually see the incident--I was most likely fixing my team's plane.)

Indoor RC flight tends to be with very lightweight electrics, often foam, in fairly large venues like large-size gyms. Something the weight of an FRC control system would need a ton more power than one of those flyweights, just to get off the ground. (And that's assuming that you were allowed to power with lipos. Hauling the SLA around, that's slightly insane.)

Flying a very small RC off of a robot could be done with comparative safety. However, it would be very difficult to also have it tethered to the robot.

Re: Crazy robot idea for this year 2
 

Rather than making the entire robot fit in the hoop, why not mount a large fan/turbine on the robot. Aiming this at the backboard of the opponents hoops with enough air velocity could make it impossible to score (the upward air speed would have to be greater than the terminal speed of the ball to ensure this) A leaf blower powered by a pair of 500 series motors could probably accomplish this.

Re: Crazy robot idea for this year 2
 

It's not just the velocity. Better to think of it in terms of energy, momentum or force.

Re: Crazy robot idea for this year 2
 

Actually, the applied force and transferred energy, in this case, are velocity dependent according to the drag equation. The fluid density, ball area, and drag coefficient are fixed (unless you are using a very narrow stream of air, which would would change the area parameter). As a result, velocity really is the only relevant property of the airflow.

Re: Crazy robot idea for this year 2
 

The shape and direction of the air stream was exactly what I was getting at. If you have a narrow air stream, drag alone isn't a great model of the situation. If you point the air stream off to the side of the ball, you have to deal with other effects—like the air stream inducing rotation (an off-centre force, or energy used to accelerate the ball angularly), and the tendency of the ball to fall out of the air stream.

Re: Crazy robot idea for this year 2
 

The issue is that the ball is rarely moving through the airstream long enough for it to have any appreciable effect on it. One of my teams did some extensive testing on this concept and deemed it ineffective. We used a ducted fan housing for a radio controlled jet powered by an 0673 FisherPrice motor to no avail.

Re: Crazy robot idea for this year 2
 

That isn't a large enough airstream. The ideal blower would be a large fan, nearly 28 inches, housed in a duct with minimum blade tip clearances and powered by something like a "V-6" (118 style) with 2 cims, 2 0673s, and 2 RS550s. For extra velocity a nozzle with a hoop sized opening could be added. If less turbulence is desired, a grid of drinking straws covering the opening would give you more laminar flow (more directional and uniform). It could me mounted on gimbals and aimed at shooters or (more likely) fixed and angled such that one could park against the fender and defend the 3-point basket. Conveniently, backspin on the balls would create a lift force away from the hoop as a result of the Magnus effect.

Re: Crazy robot idea for this year 2
 

I actually thought about this a bit more after posting, I think the best soulution would be a 37 inch diameter fan pointed up and toward the key. With all the power in the KOP motors you could achieve about 3-4 times as much power as a large gym fan. This would almost certainly deflect any shots enough to miss.