OpenRC HPD F1 Lexan Body version by condac

Last crawled date: 3 years ago

This car is designed to meet race regulation in real RC F1 races. And it have the performance to keep up with the real deal! Video of the fastest lap from a race: https://youtu.be/CIAOM8PESa4
This is a version of the HPD F1 to use a Lexan Body. Also the front and middle is redesigned. The front is stronger and middle part takes the battery 90 deg rotated.
It is compatible with the rear cradle but there is also a cradle that you build from several parts included, it is not as strong but easier to change individual parts and less waste of plastic when things break. The rear cradle is compatible with the original HPD version but there is also a wide version for this wider body and side_stabs are 2 different versions depending on combinations.
The car was designed to be printed in Nylon like 910 that is slightly rigid. But my prototype I made with prima value PLA did not break so it is very strong with PLA apart from the wings.
I strongly recommend to print the front wing in Bridge Nylon or something with similar flex. Rear wing I have used Bridge Nylon and it flex good and never breaks.
If you want to go cheap or cant find springs, I have used the spring from a ball pen and cut it to shorter length for front. And for rear you can ignore the side springs completely if you just want to go racing and print the plastic main rear spring that is included.
All parts is made in OpenSCAD and source is at github: https://github.com/condac/hpdf1_lexan
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2019 Experience update:
Materials!
Not as important as you might think. First time making this car, print all in a PLA to get started, it is cheap and easy to make replacement to things that break. When you are a beginner and learn to drive strong parts will not save you because a crash is a crash. But getting out there and start to drive and make the car work in the first place is more important than trying to figure out print settings and finding plastics.
All parts are printed in 100% infill and 4 perimeters.
Looking at my car now that have been through hell and back there is 3 parts that are original from the first prototype the rest have broken in some crash. And some parts have worn out before breaking! But there are replacement parts that have never failed also and that is what I want to share here what type of plastic that you use for upgrades.
PLA
My main car is still mainly PLA. Different PLA brands are better than other. I mainly use PrimaSelect, PrimaValue and ClasOhlson brand PLA (in Sweden) They have good toughness.
Nylon
The first alternative plastic to get is Bridge Nylon. Generic nylon might work but are often stiffer and break and do not flex in crashes (but still better than any PLA). Also keeping the parts wet and moist after they are printed makes them softer and tougher. Parts that are good in nylon:
Rear wing
Side_stab2
cradle_bottomPlate_wide
plastic_rearspring_10
And some parts that are better in nylon than PLA but will work better in other upgrades later:
Frontwing
cradle_rightBulkhead ( a bit soft and flexing in nylon but if PLA melts from motor temperature getting to hot its better than nothing)
Any temperature resistant plastic
The motor gets hot. During the hottest possible day one should tune the motor to never go over 80c/176f. I have around 55c on normal days (20c air temp) outdoor and then PLA can work. But on hotter days or on indoor tracks where the motor is working harder PLA is not working.
I have tried PETG ABS ASA as they should withstand the temperatures. But they all fail in crashes and are the worst compared to PLA in a crash.
I have also tried a generic Nylon and alloy 910 as it is a bit stiffer than Bridge nylon, but over some time the nylon will warp from the weight of the motor.
When driving indoors i accept the warp from the nylon and use it anyway. Outdoors I still search for a good material, The flex from nylon outdoors make the motor grind hard in the asfalt so not ideal. But as for now the nylon part is almost new and still not warped so it works.
PP (PolyPropylene)
The king of car crashes. Super soft and flexible but awesome toughness. I use this on the frontwing.stl. My first test with this plastic is still on my car 1 year since I made it. It have worn down to more than half its thickness on the tips that sometimes touch the ground and I have made countless front impacts and it just deforms slightly and i bend it back and drive along.
Front wing
Front Arms
There is one part that break that I have experimented with trying to make it better and that is the front arms. But believe it or not, they are extremely good in PLA. When I designed this car I made it so the front arms do not bend in a crash but they compress and send the force into the chassis, and this have worked well. Also they are printed with the plastic grains in the most optimal position. But having a front wing that is catching most of the crash is playing a bigger role.
But I have of course tried it in the indestructible PP and Bridge Nylon. But this seemed like it just moved the breaking part inward and the nose chassis break instead. So at some point something must break so it is much more easy to replace the front arms than the chassis. And having a lot of spare front arms are cheap compared to bigger parts.
But i have had front arms in PLA that have worn down the holes for the pins so the wheel wobble and I have to replace because of wear before they have broken in a crash, that might sum up how well they work.
Conclusion
When racing with this car the most common failure that have caused me to retire the car is impacts on the rear wheels. Breaking side_stabs or the cradle_bottomplate or cradle in general.
Parts that have survived over expectations are the main chassis and nose chassis. Main chassis have been worn down from toughing the ground and needed replacement because of the plastic got to thin. And the very high poles in the nose i have made so you can repair with a screw from underneath but i have never used a screw because it have not broken. The forces are just not there to bend them.