£100 speed challenge (Project Ender) TARGET 100MPH!

[Alex97]

1 hour ago, Paul Busby said:

This is a cool idea man.

When my CNC arrives I might try and join in on this endeavour and do something of my own as a learning experience

Interesting ideas with the aero as well, only point I would make about the "thumb" is that it was done like this for safety. The regulations dictate the maximum height and surface area for the front of the car, I think give the option, a lot of teams would be more angular and pointy.

if you go back to before they introduced these rules, all the cars had very high noses that suspended the wing and forced air under the car.
Obviously you can imagine the danger if one of those high noses were to slide over the top of another car towards the cockpit

No doubt once you get it yet up I might need your assistance? 

[JoeMower]

Reminds me of this

[Alex97]

Just now, JoeMower said:

Reminds me of this

Let's see if JCB will sponsor me 😂

[Paul Busby]

2 minutes ago, Alex97 said:

No doubt once you get it yet up I might need your assistance? 

We can probably help each other out tbh. I'm learning as I go for sure. 3D printer will be next on the list.

 

I'm far from an expert in any of this, I just have a bit of business cash saved up that I'm investing back in so I have a fall back business in place should we end up back in this spot again, or unable to return to business as usual (or something Brexit related).

 

I enjoy RC and I'm really enjoying manufacturing parts so that's where I'm going to push forward!

 

I think the CNC machine I have ordered (and since upgraded) will actually be able to mill out most of that shell design as one piece, so could technically make a mould and then get it vacuum formed... might slide out of budget though

[mayzie12]

Glad to see someone having a bit of fun for speed on the cheap.

 

On the body front, I might be able to help a bit. I completed my uni project a few years ago on the aerodynamics of RC cars and it's a tricky old thing as the scale of them ruins everything!

 

I'd stay away from trying to do underbody aerodyanmics personally. Get the balance right with good front aero to stop it lifting, and you can use pretty flat shaped aerofoils at the back to keep the balance of downforce at the back for little penalty in drag. Sticking on a flat floor is generally not just as simple as doing it! Admitedly i was doing a short wide car, you're doing a long narrow one, but underbody aero is the most difficult thing to get working right. And if it's wrong it causes a lot of greif.

The simplest way to do it all of us at ROSSA has found is just to leave the back of the shell as open as possible.

 

Attached my project if you want a ganders. It shows how easy it was to get a splitter and spoiler working, but soon as I chucked on a flat floor and a diffuser things start to get complicated. Rather than go on about it here I'll let you read it if you want 

ME40005_SEM0000_1617_7789527_5919348_Craig_Mays_Thesis.pdf

Edited June 26, 2020 by mayzie12

[Alex97]

1 minute ago, mayzie12 said:

Glad to see someone having a bit of fun for speed on the cheap.

 

On the body front, I might be able to help a bit. I completed my uni project a few years ago on the aerodynamics of RC cars and it's a tricky old thing as the scale of them ruins everything!

 

I'd stay away from trying to do underbody aerodyanmics personally. Get the balance right with good front aero to stop it lifting, and you can use pretty flat shaped aerofoils at the back to keep the balance of downforce at the back for little penalty in drag. Sticking on a flat floor is generally not just as simple as doing it! Admitedly i was doing a short wide car, you're doing a long narrow one, but underbody aero is the most difficult thing to get working right. And if it's wrong it causes a lot of greif.

The simplest way to do it all of us at ROSSA has found is just to leave the back of the shell as open as possible.

 

Attached my project if you want a ganders. It shows how easy it was to get a splitter and spoiler working, but soon as I chucked on a flat floor and a diffuser things start to get complicated. Rather than go on about it here I'll let you read it if you want 

ME40005_SEM0000_1617_7789527_5919348_Craig_Mays_Thesis.pdf 3.58 MB · 4 downloads

Hi, thanks for the info. 

 

 

The attachment isn't working ☹️

[mayzie12]

2 minutes ago, Alex97 said:

Hi, thanks for the info. 

 

 

The attachment isn't working ☹️

 

Classic forum attatchments

 

We'll go for the old fashioned way...

 

https://drive.google.com/file/d/1A6cNQ-AlLN1yNGCgYO61dnHrw5N1eg85/view?usp=sharing

 

[Alex97]

After a rainy Sunday I got a lot of the mounting brackets modeled up and front servo mount done. This is a cut away view, if I get time i'll model up the rear motor mount and front wishbones / steering assembly. 

 

total length is 550mm which isn't too long but the body is very low at 45mm at the front and then 60mm at the back. 

 

here's a cut away view of what the inside looks like...

 

 

The pole was a tie so I ended up going for orange. 

[Alex97]

I printed the rear floor and mounted it to the chassis. This will probably be a test car as there's a few bits I'll need to change for the final car...

 

 

 

Edit - the rear has been tweeked slightly so there's no suspension so will rely on the chassis and tires. I'll be using 1/10 foam tires so I might have to make the rear end slightly wider to allow them to fit as there won't be much room under the shell once everything is in place. I'm 90% happy with how my printer is working but room for improvement. 

Edited June 30, 2020 by Alex97

[Tony]

Following with interest.

[Alex97]

After doing a test fit yesterday the rear end was too narrow so I made it about 20mm wider which required me to remodel several parts which took a few hours however everything "should" be good now. I ordered the tires, motor and servo yesterday so hopefully within a few weeks the chassis will be finished so I can get a test run in before I start making the body just to make sure  that everything is as it should be. 

 

I've also given the project a name, Ender which is named after the 3D printer. 

 

Also here's an underside picture... 

 

[Alex97]

Right, progress....

 

 

I got the rear end and front assembly mounted this afternoon which means we've now got 4 wheels mounted to the chassis. The rear tires are 1/10 touring foams and the front are just the stock mardave ones however I'll be printing some new ones and using o rings later. I buggered up on one of the rear holes as the drill slipped so it's about 2mm to the left meaning that I've only got 3 of the 4 rear screws holding the mount in place. 

 

I've also made some tweeks to the front end so when I print the final model it will be slightly different. 

 

I've got got a 17t pinion attached however it's in the closet position so I should be able to run a 25t for the speed runs which will give me a 25t-46t gear ratio which should get me over 100mph. I'll start on the body next week but hopefully within the next few weeks I should have the first prototype finished but over the winter months I'll work on the final version. 

 

[Ag100]

Taking shape 👍

[Alex97]

Front wheel printed...

 

 

 

 

The wheel is printed and then a o ring is fitted for traction.

 

 

I should start printing the body next week however this will take a while as each piece will take around 15 hours and there's 5 parts. 

[Alex97]

The ESC arrived today, all wired up and electronics mounting plate has been designed. 

 

 

I've decided that I'll be running a super shorty battery pack as it fits perfectly into the centre of the chassis so I'll be ordering some of them soon. I gave the car a quick run on my desk and the power is crazy! Currently it's running a 17/46 gear ratio however the final will be closer to 25/46 which will give me a "true" speed of around 200mph so once aero and resistance is taken into account I reckon 100mph should be achievable.

 

Body should be started next week if not the week after. 

[Alex97]

After a few issues the electronics mount has been printed!

 

 

 

Please excuse the messy cables other than the motor cables everything still needs to be cleaned up. 

 

 

A bit of progress this week...

 

Electronics mounted designed and printed 

ESC and motor wired up

4 24v brushless fans added and wired in with a buck converter to boost the voltage

 

 

This is just the prototype chassis so as I go along things will changed as modeling something on the PC is one thing however getting it to interact with everything is something else. 

Edited July 16, 2020 by Alex97

[Alex97]

big update... 

 

I started printing off the body and found that i'd made everything a little too tight and i wasn't 100% happy. I set about re desiging the whole rear end, the sidepods and rear are now one solid part (24 hour print) and the defuser is held on with 9 screws. overall a much more solid design so worth the time. I've also got rid off the mounts internally and i'm now using two plates that will hold everything in place. 

 

 

 

[Logie]

Nice, good job so far looking brill

[Alex97]

30 minutes ago, Logie said:

Nice, good job so far looking brill

Thanks you, progress has been slow recently since lock down has been lift however I doubt I'll get any runs in this year to I've got plenty of time 😂

[Alex97]

This hasn't been forgotten however I just haven't had the time to get on with this and i've had a few printer issues so it's currently on hold, it should be a Winter project. 

 

 

[Alex97]

Update- 

 

I had a few goes at printing the body but it was around 250g all in VS a normal shell onroad shell at 75g so added quite a bit of weight plus all of it would have needed to be sanded down to reduce drag, a lot to get something i'd be happy with. . 

 

I can see why not many people have printed bodies as it allows you to get whatever shapes you want but on a budget printer unless you really know what your doing you'll always struggle. it's been a great learning cuve and reminded me how to use a lot of the CAD fuctions that i'd forgotten about, plus kept me busy during the first lockdown. 

 

This project was good fun and i've found I enjoy the design side more than the running side of RC.

 

All is not lost, i've been playing arouns with a X12 pan car and transfered a lot of the electronics to that. This has a custom made carbon fibre chassis and uses a normal 1/12 LMP body so much easier. It's ready for the first test run however everything is very damp and with a 2.5t motor even on 50% with a low tooth pinion i'll struggle to keep it in a stright line. 

[Paul Busby]

What filament were you printing with mate?

[Alex97]

2 hours ago, Paul Busby said:

What filament were you printing with mate?

PETG

[Paul Busby]

Probably wouldnt be sufficient saveing to be worth while when it's an entire body, also not exactly practical to 3D print, but I can do some bits out of carbon fibre nylon which should be about 20-30% lighter.

 

I also still don't have my CNC up and running

 

Should be early next year I get to that stage, might even have a new one if they sort this bloody brexit trade deal out.

Edited December 23, 2020 by Paul Busby
Profanity

[Alex97]

2 hours ago, Paul Busby said:

Probably wouldnt be sufficient saveing to be worth while when it's an entire body, also not exactly practical to 3D print, but I can do some bits out of carbon fibre nylon which should be about 20-30% lighter.

 

I also still don't have my CNC up and running

 

Should be early next year I get to that stage, might even have a new one if they sort this bloody brexit trade deal out.

I'm using a £150 printer, for most RC things it's great plus small things around the house. 

 

For the above model I had the chassis machined and printed everything else (other than running gear) then used an off the shelf body. 

 

 I'm using the mardave parts for another chassis, currently I'm printing the chassis to do a test fit and then I'll send it off to be made out of carbon fibre, it will also use a 1/12 LMP shell.