Tetrix Kit Possibilities

[Tassemet]

Hello all,

I was in FTC quite a few years ago, and have since been out of highschool about a year. In that year, I joined the Navy and learned a lot more about what we did electrically and physically with our robot that we never even thought about.

Going along those lines, I've bought the stuff to build with the tetrix kit just for fun here where i'm stationed and have fun with my shipmates.

During one suggestion on what to build, someone mentioned a helicopter, or some sort of flying object. In your opinions, do you believe the tetrix kit holds the possibility to make a well designed 'bot (and I mean well designed bot) fly with either a single (apache) or double rotor (chinook) design? Maybe not move around, but hover and look cool?

From what i've seen and read, the only main concern would be weight, and whether the motor or motors could spin a set of rotor or rotors with enough force and speed to pick the thing up off the ground.

And to this point, has anyone tried such a feat? If not, I still want to build things here and make some posts and videos as I go along just to try and see if I can make some magic happen.

Very Respectually,
Tassemet

[Hawiian Cadder]

I think that you could make a hovercraft without too much issue, i don't think that you could make a flying robot, maybe you could do it if you took ALL the weight of everything, but even then, i don't think that it is possible.

[Tassemet]

Also, seeing as how the kit is mine, i'm not worried about it being FTC legal. I have no problems overdriving motors a bit with more voltage then the stock battery pack comes with, or other modifications to gain power/weight advantages.

[Hawiian Cadder]

you will need to take off the integrated gearboxes on the motors. but beyond that there is not much extra performance that you can gain. the primary problem is the lack of a lightweight control system. if you used a different control system it might be possible, but still very difficult. the battery is also very heavy, and lighter batteries may not be able to power the robot for very long.

[Techhexium]

Well, the structural elements are made of Aluminum so it's possible.

Also, if you remove the gearbox from the motors, the motors will spin significantly faster than the 153 rpm indicated by the sticker on the motor.

If you didn't know, FIRST had its Aerial Robotics Demonstration (CARD) pilot in St. Louis during the championship, you may be able to find some videos in Youtube about that.

[Tassemet]

Well, the structural elements are made of Aluminum so it's possible.

Also, if you remove the gearbox from the motors, the motors will spin significantly faster than the 153 rpm indicated by the sticker on the motor.



One thing though, higher speed also means less torque. At least if what i read about the motors are right from another post on here. It seems max output achieved is around 11.81 kg/cm@76.1 RPM and for max efficiency (which is slightly under max output) 9.77 kg/cm@88RPM :yikes:

[Hawiian Cadder]

I think that it might be possible to build a flying robot, with FTC, but in the end there would be so few originally heavy ftc parts left that you might as well build it from scratch.

[Tassemet]

To be completely honest, we're doing this as a proof of concept deal with this kit. If it can do it, cool. If not, oh well.

We're that itching to apply what we've learned at school here, and that bored here between school and taking care of our duties as military forces that we want to try something completely crazy and potentially impossible just to do it.

[PayneTrain]

Given my experience with Tetrix, you might as well buy a dozen motors and save yourself from the grief of waiting for new ones... XD

[Tassemet]

Thanks for the advice, but I don't think i'll be burning out motors by rotating rotors.

[EricH]

Thanks for the advice, but I don't think i'll be burning out motors by rotating rotors.
FRC teams blew out quite a few FTC motors in the minibot competition. High rotational speed, light(ish) load. There's an inductor that's apparently quite susceptible to blowing out under some load. Whether or not spinning a rotor will do that, I'm not sure.

[Chris is me]

Stall that motor for more than 2 seconds and you're blowing that inductor.

[gblake]

Go to the Vex forum and search out the thread (it existed during last the last North American school year) that talked about trying to do the same thing with Vex parts.

Some of the contributors to that thread knew enough about aeronautics (or knew someone who knew) to make some reasonable assessments of the physics involved.

See if that info (or a resurrection of the conversation using Tetrix specs) can answer your question.

Also consider figuring out how much thrust you can create (by experimenting) using the motors and an appropriate prop. That will get you the bulk of what you need to know about maybe building a quad- or tri-rotor flyer.

If you want to build a true variable pitch helicoptor rotor, I think you are barking up the wrong tree. The Tetrix parts just aren't useful for making the small intricate mechanisms/controls that are the essence of a modern Apache/Chinook helicopter.

Blake

[PAR_WIG1350]

If immersed it in a denser fluid, such as mineral oil or water, it might be very possible. The rotors could be run at lower RPM (possibly with the stock gearbox attached) and the buoyant force would reduce the amount of lift that the rotors would need to provide. It might help to contain the motor(s) in a diving bell an run chain drives to the rotors. The greatest issue might be finding a suitable fluid and a vessel in which to contain it.

I'm not crazy, I just like to think :p .

[Tassemet]

Well, I have access to a lot of electronics measurement things here, whether I can borrow them or not though....

If it's an inductor that blows, that's an easy fix provided I know enough about it (size, resistance values etc.) to replace it.

Also, I didn't know those motors will blow out under a low load at a high RPM, it seems strange unless they were running them full out/overloading the motor. In that case, yeah. There's actually a forum where I pulled the exact specs on the power of the motor. Again from my post above, running them at maximum power seems to be the way to go.

As for the water tests, i'm not making this thing under water. Nor do I have access to a water tank/a way to keep electrical parts dry.
As for the apache style and micromovement, I have an idea that involves a universal shaft joint (like the kind found on a drive-shaft of a car) and some parts that will rotate the top half with a servo (aka pitch the rotor forward or rearward) while the body more or less stays still. Obviously, I have a lot of drawing and design still to go, but I think that having the whole rotor pitch forward will cause forward and rearward movement. I haven't thought about how to get left and right in, but one thing at a time, right?

Another option I have is something along the lines of a chinook- 2 motors 2 rotors versus the apache 2 motors, 1 rotor. Again, weight has to be kept to a minimum I understand, which is something I'm taking seriously into my design aspects.

Still, I'm waiting for my kit to come in... only 3 days left XD Until then, I'm working the theory/design aspect with some friends at a local hangout here. It's going to become our place to build, and the field outside will be our testing bed once we get too serious with rotors and such.

Speaking of rotors, which is a better design aspect, 2 bladed, 3 bladed, 4 bladed, or 8 bladed rotor, and should it be once piece or 8 individual rotors? I'm terrible with helicopter theory and my understanding of it is limited at best :(

[Tassemet]

If immersed it in a denser fluid, such as mineral oil or water, it might be very possible. The rotors could be run at lower RPM (possibly with the stock gearbox attached) and the buoyant force would reduce the amount of lift that the rotors would need to provide. It might help to contain the motor(s) in a diving bell an run chain drives to the rotors. The greatest issue might be finding a suitable fluid and a vessel in which to contain it.

I'm not crazy, I just like to think :p .

Explosive/flammable in great amounts?

[Alan Anderson]

Explosive/flammable in great amounts?

Mineral oil won't explode; it isn't nearly volatile enough. Its flash point is well above what would make it a flammable liquid. Mineral oil will burn (and produce nasty smoke) if you put it in contact with something hot enough for long enough, but that's true of many substances.

Perhaps you're thinking of mineral spirits?

[Tassemet]

Mineral oil won't explode; it isn't nearly volatile enough. Its flash point is well above what would make it a flammable liquid. Mineral oil will burn (and produce nasty smoke) if you put it in contact with something hot enough for long enough, but that's true of many substances.

Perhaps you're thinking of mineral spirits?

DOH! Of course I was thinking mineral spirits :yikes:

[EricH]

Well, I have access to a lot of electronics measurement things here, whether I can borrow them or not though....

If it's an inductor that blows, that's an easy fix provided I know enough about it (size, resistance values etc.) to replace it.

Also, I didn't know those motors will blow out under a low load at a high RPM, it seems strange unless they were running them full out/overloading the motor. In that case, yeah. There's actually a forum where I pulled the exact specs on the power of the motor. Again from my post above, running them at maximum power seems to be the way to go.
Quite a few FRC teams had a lot of trouble finding those inductors. I think someone did find a pretty close substitute; it's slightly larger than the one there. (The other option, at $30 a pop, was to replace the motor.)

I'm pretty certain that the FRC teams were running at full power to go up the pole (the entire idea was to get up the pole as fast as possible). If you have a heavier load than the pole-climbers, you'll almost certainly blow out inductors, repeatedly.

[Tassemet]

It sounds like a case of overloading the motors weight wise or having them reach a stall condition (aka 0RPM) which I expect draws too much current?