After I’d managed to break my F1 car the first time I Drove it Outside, I thought it was time to road test the new and improved version again.
You may remember from my last article in this series that I’d spun the car at high speed and managed to sheer three axles, completely losing three wheels.
Well, after reprinting them at 100% infill and after a little ‘safe’ test drive in my kitchen it was time to hit the road again, but this time I was going to film it all!
It’s winter time here in the UK so finding a dry day can be tricky. Although I avoided the dark this time I, ended up taking the car out on damp tarmac. I never learn do I?
Before I took the car outside I needed to tidy up the electronics a little. This was for a few reasons:
- Crash Protection – So the lid would fit holding everything in safely
- Weight Distribution – Ensuring the car was well balanced
- Cooling – Making sure the speed controller fan wasn’t obstructed
- Promises – I previously said I’d do this and report back to you
Now, I’m not saying that the layout is amazing but it’s functional and it all fits in this way. My wires are longer than they need to be so at some point I might do some trimming and re soldering, but for now I’m happy.
As you can see from the picture the speed controller is at the back with the fan facing forward in a little open space.
The battery is towards the front and the switch is hanging outside the car ready to be trapped by the lid. This is intentional as for testing I prefer the switch to be immediately accessible.
The receiver, well that’s no where to be seen? It’s actually hiding just above the steering servo and you can just see it if you look carefully. This position allows the antenna wire to feed through the little hole in the lid, which I believe is actually intended for attaching a driver and helmet to the car.
With the electronics in place, I’m now ready to take the car outside for a little test drive, just as it starts to rain.
OpenRC F1 Car Road Test
For this test run I decided to take the car on a quiet little tarmac lane. There is some gravel so I need to be a bit careful as my tyres are rock hard and this could send the car all over the place.
I set up my camera and started the test drive. The rain had stopped by now but as you can see from the video, the road is mostly wet and the wind is in full swing.
You may notice that in this video I only have half a front spoiler. That’s because after I’d broken it a few weeks ago I decided to glue it temporarily, knowing I’d break it again.
Just before I shot this video the car ran over a stone about the size of a pea, bounced up and broke the front spoiler.
It’s also worth noting that after this video was taken I managed to roll the car and break the other half of the spoiler too. Somehow the rest of the car survived!
I was filming at the time but unfortunately the car was out of camera shot when I rolled it, so I haven’t published this video. I might do though as the clattering sound is entertaining, just after the car has sped past the camera.
All is well now though and I consider this test driver to be a success, partly because the new, stronger axles all stayed in one piece and partly because I learned a lot about how to improve the car.
Two things you’ll notice about the cars handling:
- The car bounces a lot, especially over the gravel
- The rear end is difficult to control under power
I do have potential solutions to both of these and have already started to make these improvements, which I’ll complete before the next road test. Let me elaborate on these solutions…
Much Improved Tyres
What worried me about using a thickness of any less than this is that the tyre walls would be too thin, as I had found on previous Tyres I’ve Designed and Made.
I have solved this by creating a custom profile in my Makerware slicer, so that I could keep the tyre walls at 2mm thick, but reduce the thickness of the surface of the tyre right down from 4mm to 1.2mm.
I have 3D printed a single tyre with these new settings and the new tyre is worlds apart from the original ones I have on the car now. The tyre is great, but I ran out of NinjaFlex so I’ve immediately ordered more so that I can 3D print the other three tyres using the same settings.
Although it’s tricky to quantify the difference in softness, I can tell you that if I squeeze an original tyre (while fitted on the wheel) as hard as I can the tyre hardly deforms at all. It’s basically rock solid.
Now, look at the picture of the new tyre fitted to the car and resting on a green peas sized object, only under it’s own weight. This is the size of the stone that almost flipped the car during testing and broke the front spoiler.
Looking at this image you can see that the new tyre will easily absorb such an object and handle rough surfaces much better. Only testing will tell, but I’m excited that this is a massive improvement over my original tyre settings.
This will certainly improve the cars ability to handle bumps and reduce the bounce I’ve been seeing in testing. It’ll also improve grip and so help me keep control of the rear end under acceleration.
Oh and after weighing the old and new tyres there’s a 19 gram saving in weight for each tyre, so the rotational mass and overall weight of the car will be significantly reduced too. Bonus!
There’s more, I have another exciting solution to the unpredictable rear end issue and when I read about someone else who’d used it and seen the improvement first hand in his video, I just had to give this a go. It’s so good, it might be considered cheating.
Vehicle Stability Control
Part of the problem with the rear end of my OpenRC F1 car build is that I cannot accelerate to anywhere near full power without the rear end snaking to the point where I lose control completely.
My driving skills aren’t quite up to controlling this and my reaction speed (I’m now 40 you know) isn’t as good as it used to be either. So it’s time to cheat and use a little electronic vehicle stability control.
When I’d heard that a guy called Larry Fortna had used a flight stabilizer to auto correct his steering when his car went out of line I was very intrigued.
What it does in my car is apply the brakes to different wheels independently to correct the course of the car in the event of the car suddenly not pointing in the direction that was expected.
Luckily it’s only activated itself once, but it was useful and probably kept me on the road. With an RC car you don’t have independent braking on each wheel, but you do have electronic control of the steering.
What this flight stabilizer does is fit into a radio controlled aircraft, using a gyroscope to automatically adjust the pitch, roll and yaw to keep the aircraft flying straight in windy conditions.
If you think about it, there’s little difference between adjusting the rudder in a plane when the yaw changes unexpectedly and adjusting the steering in a car when the back end skips out (effectively the yaw changing suddenly).
Now I’m no flight expert, but I can see how connecting a flight stabilizer between the receiver and the steering servo using the rudder inputs/outputs might just work.
Check out Larrys video and you’ll see how stable his car is. I appreciate that it looks hot and dry where he is, but with his flight stabilizer installed that car looks mightily controllable compared to mine.
Yes, I’ve ordered the same flight stabilizer myself. It was only about £12 from HobbyKing, with the male to male servo cable (sold separately) which I also need to connect it up. It’s fully adjustable with reverse switches too, so it should be easy to setup.
When the flight stabilizer and the new NinjaFlex arrives I’ll fit the stabilizer, then 3D print and fit the rest of the new tyres too. Expect a new, improved road test coming soon and you might even see my newly 3D printed front spoiler by then.
To find out more about this project visit my dedicated OpenRC F1 Car Page.
Also, why not join my 3D Printing Facebook Group for the real inside information on this and other exciting projects. You can even post your own projects there!
Thanks to Daniel Noree for making this amazing OpenRC Formula 1 car design available to the public and thank you for reading and taking an interest in it.
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