The Fan-Pushed R/C Cart A.k.a. the Computer Cart

Introduction: The Fan-Pushed R/C Cart A.k.a. the Computer Cart

I've decided to do something different and am actually telling you, the viewer, now that this is a work in progress. As I write this, the cart is still being perfected. Also this is a video documentary, with the "steps" being the different versions explained both in video and text, and running footage of the later versions.

The Computer Cart. It's not blistering fast. It can't turn on a dime. It can't go in reverse. It's neither the biggest nor smallest r/c car out there, and knex r/c cars aren't anything new (in fact, I believe knex themselves sell a few r/c building sets). So why? What was the point of this? The answer; to enter it as a TSA project (1%) and just for pure fun (99%!). We wanted to make an r/c vehicle so unique that it would be awesome and fun to drive even if it wasn't the biggest, baddest r/c cart. I think we can say we accomplished that more or less judging from the picture. That is the current version as of the day this video log was originally posted. Looking at it, it is a cart built out of knex, riding on mismatched wheels, controlled by a 6-channel r/c airplane transmitter and receiver and two servos(also off the airplane), powered by a 3 cell lithium polymer battery (also off the airplane) and a 5 volt regulator for the receiver, and pushed about by a computer fan. I think the cart speaks for itself! And this car looks radically different from the first versions. This video documentary will show this cart and its transformations as we go through the versions and improve the cart.

Oh I almost forgot, you might be wondering who built/contributed to this. Well:

Build Team
- Eduardo Perez
- Robert Meyers
- Mike Aleman
- Tray

Thank You To:
- Ryan Bishop (Donated Servo and First engine, the Nidec)
- HP (Donated second and current engine, the Delta)
- Mr. Doyle and Mr. Zimmerman (for letting us work on the project)

Step 1: Before We Begin...

     Lets talk about the engine and the different engine configurations the cart has gone through before settling on the Delta .  The engines are computer fans, completely stock.  From Version 1 to 4.5, the main (or sometimes only) drive engine was a Nidec Beta V Series TA 350DC Brushless Fan.  It arrived in a plastic green case at our little workshop room (Thank God our Tech teacher was nice enough to give us our own little room to build in so we don't have people constantly bugging us and touching our stuff.  It really does happen!).  We removed the green case.  It is the fan in the first picture.

A little info on this fan:

- It draws 2.3 amps at 12 volts
- It has an awesome feature built in which I call 'Safe Start' that first powers the fan on at low power to ensure the fan can spin.  Once spinning is confirmed (takes about 1.5 seconds), the fan kicks into high gear and spools to full speed.  If it can't spin, power is cut for 6-10 seconds before attempting to restart.
- It has pushed Version 4.5 to a top speed of about 5-6mph.  Not bad for just one computer fan pushing the cart (not the most frictionless thing, it's those knobby tires) and all the electronics.

     In addition to this fan, we've added a cool-master, traded it out for a slightly more powerful fan of unknown manufacturer, took that one off, and finally overhauled the main engine for the Delta.

     The Delta fan was also given to us, and what a find!  One of our build team member's dad works at HP, and they were throwing away a server rack cooling fan because it had a damaged front fan bearing, still ran though (more on the problem in the first running footage of Version 5).  Hp instead gave it to his dad, who gave it to our group.  Thank you HP!  It arrived at our little workshop room in a metal casing and, as seen in picture two, we immediately proceeded to remove it.  Now in all seriousness, we are not completely reckless; we have reasons for removing the grills.  The grills in both cases were removed to minimize size and weight.  Although the fans are mounted to a children's toy (knex frame), the cart will never be handled by children.  The people who DO handle the cart know not to stick any fingers or other body parts into the rotating blades.  Finally, The power is cut (battery unplugged) every time we deal with the fan.

Some info on this fan:

- It is a Delta GFB0912GHG Brushless Fan.
- It draws 3.3 amps at 12 volts.
- It has two counter-rotating fans in the same case!
- Each fan has the built in "Safe Start" feature.  The fans are independent from one another.
- Top Speed with this engine is unknown at this time (I just fixed a random throttle cutout problem, more on that in the first running footage of Version 5).

Now that we've talked about the engine a bit, let us go back to when this all began, Version 1.

Step 2: Version 1

August 28, 2011

     This is it, the beginning, the first version.  Recently, at this time, I received the Nidec Fan, and decided to test it's thrust power.  Turns out, the fan was powerful enough to convince me to proceed with the project.  Once I took the video seen below, I showed it to the other members of the build team, and they liked it too, so we continued to advance the project.

Features of This Version
- 3-wheeled stance
- Basic frame (Quickly built for this test)
- Single engine
- No throttle control
- No steering control

Step 3: Version 2

September 11, 2011

    I'm saying this now, yes the video quality is extremely poor.  I apologize, but I didn't realize that the settings on the camera were set to poor quality until a few days after the video was shot and the picture taken, and by then Version 3 was in the works, so this was the only video available.  Now that this project was official, a better, sturdier frame was whipped up.  The frame was designed so that the rear wheel could pivot, and a servo neatly nestled into a groove in the rear of the cart.  Wires were then strung from the servo to the rear wheel, and we got steering.  The receiver was zip-tied somewhere on the cart, and a 6-volt lantern battery was used to power it.  A crude battery cage was added to hold the lithium battery. A second fan was added, the Cool-Master 0.3 amp, 12 volt Brushless Fan.

Features of This Cart
- 3-wheeled stance
- Reinforced frame
- Dual engine
- Very slow (over-weighted, a lot slower than walking, max speed around 1 to 1.5mph)
- Steering control
- NO throttle control (plug in and watch it go, crash it somewhere and unplug it to stop.  Not a problem since the cart is so SLOW).

Step 4: Version 3

September 15, 2011

     The 3rd Version.  This one was the first version with throttle control, though the throttle control requires two additional batteries in addition to the two already on the cart, and an additional controller and receiver (in the black box).  We got a slightly stronger fan of unknown company (12 volt, 0.56 amp Brushless Fan) to replace the Cool-Master.  I managed to find a four-AA battery holder and used that to replace the heavy 6-volt lantern battery.

Features of This Cart
- 3-wheeled stance
- Reinforced frame (same as Version 2)
- Dual engine
- slow (over-weighted still, but not as badly, max speed around 2.5 to 3mph)
- Steering control
- throttle control
- currently running on four different battery packs (six if you include the two transmitter battery packs)

Step 5: Version 4

September 24, 2011

We finally got a control board soldered up, complete with 5-volt regulator, relay to trigger motors and throttle control board. What this means is that the entire setup for the first time since Version 1 can run off of one single battery! The black box is gone, along with the rechargeable 3 volt (inside black box), the 9-volt, the four-AA battery holder, and any temporary mounting pieces for the components that were removed.

Features of This Cart
- 3-wheeled stance
- Reinforced frame (same as Version 2)
- Dual engine
- This version attained max speed that can be achieved with this engine (max speed is ~5mph)
- Steering control
- New throttle control
- Currently running on one battery pack and SINGLE transmitter and receiver.
- Unstable at high speed, prone to tipping (see 2nd running footage video, 2 steps ahead)

Step 6: Version 4 Running Footage 1

September 25, 2011

     Here is video 1 of version four in action.

Step 7: Version 4 Running Footage 2

September 25, 2011

  Here in video 2, you'll see what I meant in the intro to Version 4 by "prone to tipping".

Step 8: Version 4 Revised (4.5)

September 27, 2011

So if you payed attention in Version 4, you'll remember the throttle board was generating too much heat. Well it burned, so we were back at square one. We came up with the mechanical throttle shown in the video. Though not shown in the video or the picture (was done after they were taken), the top fan was removed after testing the cart without it proved it wasn't adding much thrust and was just draining the battery and making the cart unstable (high center of gravity). Also the original servo arm was found and added to the throttle servo.

Features of This Cart
- 3-wheeled stance
- Reinforced frame (slightly different than Version 2 to accommodate throttle servo)
- Single engine (see end of video)
- This version also attained max speed that can be achieved with this engine (max speed is ~5mph)
- Steering control
- New(er) throttle control
- Currently running on one battery pack and SINGLE transmitter and receiver
- More stable at high speed thanks to removal of top fan (see end of video), less prone to tipping

Step 9: Version 4 Revised (4.5) School Running Footage

September 28, 2011

     We got the chance to run this thing at school, which is where we've been working on this since Version 2.  While I was at it, I realized that we were caught on camera, though we show up blurry because the knobby wheels and the tile makes the camera shake constantly.  Either way, I pointed out the four build team members, the rest of the people were spectators.  One of the members, Tray, appears late in the video, so keep watching and you'll eventually see him.

Step 10: Version 5

October 4, 2011

Well, so far, this is where we are right now. As mentioned in the video, the new Delta engine was originally ran in Version 4.5. We had the intent of keeping the fan on 4.5, however the swaying rear wheel proved too unstable. So, determined to achieve stability at the higher speed the new engine provides, the basic frame was kept, but radical modifications were done. The new front assembly accommodates the new steering mechanism and new battery cage location (battery cage was kept the same, just shifted forward). The cleared up space in front of the fan houses the steering servo, and new wires were strung from the servo to the steering mechanism (not the best way to steer, but it works). An axle was added to the rear of the cart, which now holds two rear wheels instead of one. The frame kept sagging because it wasn't designed for two rear wheels, but a few parts changed out and we were back in business. The fan was fixed after the 1st school running video. Also, eventually you'll see the wheels will be different than those currently on the cart.

Features of This Cart
- 4-wheeled stance
- Heavily modified reinforced frame
- Single (new) engine
- This version's new max speed is unknown at this time, it's not finished completely yet
- EDIT 10/20/11: Max speed, without either camera, is ~8.5mph
- Steering control
- Throttle control
- Currently running on one battery pack and SINGLE transmitter and receiver
- Extremely stable at high speed thanks to four wheels and front steering, NOT prone to tipping

Step 11: Version 5 School Run 1

October 5, 2011

The first ever run of this Version, and it's apparent that we need to do some work. The drifting, while fun, is annoying when you're going for top speed. IGNORE THE END OF THE VIDEO!!!! It turns out the random throttle cutouts were a battery connection problem. The fan spool-up time is unacceptable; the video explains this in the beginning. In this run, the grey connectors that "tend to slide apart" (see picture in intro of Version 5) were still in place, and when i crashed at the end of the video, the front ones slid apart. It also disconnected some steering parts, which is why at the end it crawls back into the room.

Step 12: Project Progress So Far

October 13, 2011

This is where we are right now. For the most part, I've fixed the throttle cutout problem. We replaced the grey connectors that slid apart. Probably the biggest thing is that we fixed the engine!! Turns out, the bearing was fine, but the ring which properly seats the fan on the bearing was worn at one side. After securing the fan back in the right position, we epoxied the front of the front fan, filling the gap between the fan and the ring. Now it spins beautifully! The tires are giving us trouble now; our attempts to replace them with self-made tires with more grip have only slowed down our cart significantly. We're thinking thinner tires, we'll try that next. Oh yeah, did I mention we got a camera video transmitter/receiver? Once mounted it will send us a live video feed of what the cart is seeing, so we can control it from another room! Now we need a tv...

(Actual) Picture coming soon...

More to come as we continue with this project, thanks for watching/reading and stay tuned!

Step 13: Version 5 Bugs Fixed

October 20, 2011

The cart no longer has random throttle cutouts! Also that issue over the wheels having no traction was fixed. The wheels on the cart in the picture are the normal wheels. They give maximum speed, but don't have too much grip (they still give enough grip to control the cart at max speed). If you're a good driver, you can actually drift the cart without spinning out. If you can control the drift, it's not a problem. If it's really needed though, the front wheels and the rubber for the rear wheels shown in the second picture can be added. They give a tremendous increase in grip, but sacrifice some speed for it. Luckily, with the current knex design, wheels can be swapped out quickly and easily, so switching between the two options isn't a problem.

Step 14: Version 5 Second Run

October 21, 2011

Second run of the cart. In this run, the cart actually is carrying more weight than normal. It's carrying the new wireless camera and 9 Volt for it, as well as the recording camera. Max speed has been reduced to ~7.5mph int his run.

Step 15: Wireless Camera Attached

October 25, 2011

Robert brought in this really old and small TV...perfect! In the video, we're testing the camera by doing a little driving by just looking at the live feed on the TV. The receiver for the camera currently has the stock antenna attached, this will eventually be swapped out for something bigger. Small 'oops' at the end.

Step 16: Progress So Far

October 25, 2011

We are working on getting a better antenna for the camera receiver so that we can receive picture from a remote room. We need to get measurements so that Robert can begin to design the frame for the 3D Printer

More coming soon!


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