03-07-2006 12:28

Tytus Gerrish

Re: pic: Twin Fan Powered Vex Prototype#2

ahh cool! does it work? where did those fans come from?

03-07-2006 12:56

Wetzel

Re: pic: Twin Fan Powered Vex Prototype#2

Can you reverse the direction of the fans?

Wetzel

03-07-2006 13:37

Re: pic: Twin Fan Powered Vex Prototype#2

As for steering, a servo controlled flap behind the fans, and putting an omni wheel on the front wheel would make steering like a boat possible.

For braking, a servo with a piece of rubber on the arm pressing onto a main axel, so once you disable the fans, the servo acts as a brake.

03-07-2006 13:38

Jeff K.

Re: pic: Twin Fan Powered Vex Prototype#2

That is a work of VEX
lol

When you say main axle, do you mean rear axle, and are both wheels on the same axle?

03-07-2006 15:08

Arkorobotics

Re: pic: Twin Fan Powered Vex Prototype#2

The fans I got at Hobby People, they are High Power Lightweight FAN UNIT.

The Speed Controller clames to be reverseable but it doesn't do it on the VEX set.

The flap wont do much because the vex set itself is not really aerodynamic, but I will give it a shot.

The axes are seperate one axis for one wheel and one for the other.

03-07-2006 15:24

i like dirt

Re: pic: Twin Fan Powered Vex Prototype#2

I think I have an idea to help you with your steering. But you're going to have to sacrifice your original 3 wheel design. I suggest you turn it into a 4 wheel drive and using a rack and pinion setup of gears turn it into a car drive.

03-07-2006 15:28

Dan Petrovic

Re: pic: Twin Fan Powered Vex Prototype#2

Or couldn't he just rotate the one front wheel he has now?

The tread would have to go back on that wheel, though

03-07-2006 16:30

Mike AA

Re: pic: Twin Fan Powered Vex Prototype#2

or, if another speed controller is acquired you could use the fans for steering. Slow one down as you turn its direction, kinda just like our larger robots...


-Mike

03-07-2006 17:00

1902_Battery_SGT

Re: pic: Twin Fan Powered Vex Prototype#2

for steering how about putting a servo on the front wheel?

03-07-2006 17:59

billbo911

Re: pic: Twin Fan Powered Vex Prototype#2

Read this reply I put on your first thread, it may help you with the speed controller issue and reverse.

03-07-2006 18:58

Arkorobotics

Re: pic: Twin Fan Powered Vex Prototype#2

Yes! Your were right when you put it to neutral it stops then when you reverse it goes backwards, but not on full power. This means I can steer and brake by going backwards. W00t thanks so much! My plan B was to do it like jets when they land on aircraft carriers with that rope and hook idea. Thanks so much, I will try to get a video of it as soon as I can.

04-07-2006 14:06

bear24rw

Re: pic: Twin Fan Powered Vex Prototype#2

Are you using the stock motor on the fans?

04-07-2006 15:09

Morgan Gillespie

Re: pic: Twin Fan Powered Vex Prototype#2

As for steering you can do it the same way new cruise liners do it, rather than put a rudder behind the fan turn/angle the entire fan. This if done right would take -/= power to do that moving rudders or turning the front wheel. This technique has made cruise liners much more fuel efficient and is now standard, granted this is air, not water and fuel isn't your concern. It is still a way to solve the problem at hand.

05-07-2006 16:29

travis48elite

Re: pic: Twin Fan Powered Vex Prototype#2

I must say that is very initiative and cool! I would like to see that thing in action!

05-07-2006 20:21

Arkorobotics

Re: pic: Twin Fan Powered Vex Prototype#2

You know how jets landing on aircraft carriers with a cable, does anyone think that would work for this? Like have a cable out and have it hook on and slow it down?

05-07-2006 23:47

bear24rw

Re: pic: Twin Fan Powered Vex Prototype#2

The only thing that i can see possibly going wrong with that is if it hit the cable and then bounces back... Do you plan on just having a length of cable pulled taught between two poles or something?

06-07-2006 00:20

Andrew Blair

Re: pic: Twin Fan Powered Vex Prototype#2

Why not just have it track in a circle? Bind up one wheel a bit, get in a large area of pavement, let it go, and when it comes back around at 20 mph, throw a coat on it.

Or you could just grab a friend and put him 75 yards downrange.

06-07-2006 01:08

bear24rw

Re: pic: Twin Fan Powered Vex Prototype#2

Instead of binding a wheel why not just angle the front one?

06-07-2006 01:37

Arkorobotics

Re: pic: Twin Fan Powered Vex Prototype#2

ummm .. I did that to my friend and trying to catch a chunk of metal going 20MPH that has 2 fast fan blades is not a good idea. He actually slowed it down by kicking it a bit (not enought to damage it) and then jumped forward and used his hands to stop it. You can really get hurt trying to stop it.

It also now has a name now, it's called "Kamikaze". The reason is that if you don't stop it .. it will commit suicide. There are no brakes no controls and it's going 20MPH in a specific direction, so it's a Kamikaze... sorta.

06-07-2006 14:52

Nuttyman54

Re: pic: Twin Fan Powered Vex Prototype#2

you could make it like a control-line plane and just tie a string/cable to it

07-07-2006 23:41

sanddrag

Re: pic: Twin Fan Powered Vex Prototype#2

I just drove my RC car with the same speed control and there is something like a 1 second delay before you can go into reverse. And just like you said, there is less power in reverse. Make sure you calibrate it though if you haven't already. There's a chance you may get slightly increased performance.

08-07-2006 13:29

amos229

Re: pic: Twin Fan Powered Vex Prototype#2

i would position a servo on each wheel and then just rub one wheel or the other with a bar connected to a servo. hit both wheels to stop.

09-07-2006 17:28

gblake

Re: pic: Twin Fan Powered Vex Prototype#2

Steering & Braking Options (some already discussed)

• Two Hooks, one on each side. A servo on each can drag the on the ground to steer. Put both down to slow down or stop like a carrier landing.

• Two bars, one on each side. A servo on each bar can drag that bar on a rear wheel to slow that wheel.

• Get control over the fan speeds.

• Mount the fans on rotating platforms aimed by geared servos. Point the fans toward opposite sides to stop. Point them at the same off-axis point to steer.

• Stop (once) by deploying a parachute that is attached to the car and catches all the wind from the fans.

• Turn (and slow/stop) by dropping raising baffle plates behind the fans. To stop have the plates block all thrust coming out of the fans (leave a gap between the plates and the fan.

• Turn by putting a rudder (on the nose or) aft of the fans. Aft is better.

• Stop by lifting the nose wheel and letting a nose mounted skid plate create enough friction to slow you to a crawl.

• Turn by making an "active" chassis that uses a servo to slightly alter the rear wheel alignments and makes the robot turn.

• Stop by running into a pillowcase or net (or high grass).

• Stop by running your power through a switch that only remains closed if you have a command from your remote telling a servo to keep it closed. Good for safety...

[edit]

• My wife Jodie came up with this one - Raise and lower air-dams (sort-of like the ailerons on a wing) to create enough drag to turn it, instead of using a rudder.

• Instead of popping a chute; for a one-time stop, you could drop a grappling hook or anchor.

I still like the idea of plates that open/close over the back of the fans to let thrust out and/or point it. It will have sort-of a jet engine look to it; can be controlled by chains and sprockets from the middle of the machine; and if the default is to block the thrust, they will give you both a smoothly controlled start-up and a failsafe mode (I think you can rig this using just the default code).
[/edit]

Also - Put some shielding (strong screening won't hurt airflow but will keep fingers and other debris out) on the front and back of those fans, and some padding on the leading edges of this missile. Do it before someone gets hurt....

Blake

09-07-2006 17:59

Arkorobotics

Re: pic: Twin Fan Powered Vex Prototype#2

The two hook idea is excellent I think I will try that, it is cheap and easy to make. Plus I just want to experiment around, I want to see if it works. So thank you.

And yes.. I did put a cover over the fans that don't effect the intake, and still give out the same power.