Lotus E21 construction report part 27
Wheel design, wheel nuts and a real premiere: the first time I designed a working rear light.
The wheel nuts are a pretty simple. Indeed, I was not able to include the female features for picking up the wheel gun adapter. However, one wheel nut consists out of fife elements. Basically it is only two cylinders and a conical frustum. The wheel hubs are fixed to the rims on order not to lose them during a pit stop (this system was introduced in 2012 I think).
The wheel design was a lit le bit tricky. I needed three approaches to get them done:
1. The first approach (with white paper – because I was not able to find structural cardboard in the correct colour) was designed as medium size wheels. Page 44 of the 2013 FIA Formula One regulations:
12.4 Wheel dimensions:
12.4.1 Complete wheel width must lie between 305mm and 355mm when fitted to the front of the car and between 365mm and 380mm when fitted to the rear.
12.4.2 Complete wheel diameter must not exceed 660mm when fitted with dry-weather tyres or 670mm when fitted with wet weather tyres.
My wheels were designed with 33mm at the front and 37mm at the rear. I made a dimension check with the finished rim cylinder (without spokes). There, I detected, that the rear axle was about 4mm and the front about 3mm too wide (max. 180mm). So this design was dumped in a very early stage.
2. For the second approach, I found a cardboard, which has almost the correct colour. However, the rims are covered with a thin paper in the correct colour. In this approach, I designed the wheels to the minimum allowed distance. This time I made it to the complete rim with spokes, followed by another regulation test. To my astonishment, the car was to wide by 9mm at the rear and 7mm at the front.
The reason for this was, that the spokes collided with the brake calipers, so I had to redesign the whole cross section of the rims. One of the largest design faults I’ve ever done…
3. For the final approach, I redesigned the whole cross section with highest care and to the minimum dimensions permitted. This approach finally works and the car should be just within the regulations by less than half a mil.
At the moment I am waiting for the OZ logo which my dad is reworking it graphically (the logo is bent around the rim radius and I do not have a powerful photo tool to do this). Most of the tires are also finished and only waiting till the rim is lacquered.
And finally, a premiere: For the very first time, I designed a working rear light. It was a bit of a challenge to find appropriate electronic components. The geometrical boundary conditions are 9.5mm x 11.5mm in cross section (inner dimensions of the rear crash structure). Finally, I found a 6V micro cell battery (for an LED, a minimum voltage of 3V is required) with 10mm in diameter and 16.3mm in length. A sliding switch with 20mm x 14mm x 8.5mm was too large. Even if I removed the unnecessary material, the switch is too large. So my electronics consists only from the battery with a cardboard pick up structure, two LEDs incorporated in the light housing and wiring. It is just enough space to get it fit into the rear crash structure.
Lotus E21 construction report part 26
Engine cover with PDRS, internal areo devices, fitting last barge boards and starting wheel design.
A lot of time passed by since my last post, mainly caused by moving into a new flat. However, I can report some new bits on the car.
First to the engine cover. Maybe the most tricky part/assembly on the whole car. As mentioned in the previous post, I cannot produce the engine cover exactly to its original dimensions, but I have to adapt it to the bodywork that is already fitted to the car. This is a process, that usually takes a lot of time and several prototypes (up to twelve in case of a Renault R26 ten years ago) are made on my previous cars. On the Lotus I surprised myself in building only two protoype engine covers till I reached the ideal shape. The engine cover consists of five main elements (one cover each side pod/radiators, one over each side of the engine, central piece at the top/airbox) plus the PDRS duct.
PDRS means Passive Drag Reduction System and is actually a passive f-duct system. A few teams (for example Lotus and Mercedes) tried to get them work and actually tested them on track. As this system with its (passive) fluid switch is highly complex and no team was able to get it work properly (as far as I know and remember). Also Lotus aborted the project after FP2 at Belgium GP in 2013. However, due to their limited resources, they used one airbox with its PDRS inlets over the entire season and only closed them, when PDRS was not in use.
Secondly, the shape of the internal areo covers are finished and only needs to be covered with carbon texture. The intention of the internal areo devices is to reduce the drag of the internal airflow. These internal areo covers appeared first in the 2009/2010 season. They mainly cover the engine and secure a relatively clean surface to minimise the drag for the airflow which exits the radiators.
I also started to fit the last barge boards, which I already produced a few month ago, but did not fit them in order to prevent damage in the course of working on the car. Now, the car is almost finished, and I don’t need to work at the car directly any more – so no more danger of damaging them.
The last major project are the wheels. Unfortunately I was not able to find a proper gold paper (the Lotus rims were painted in gold each year). So I have to produce the structure of the rims from white paper and cover it with thin gold paper. Not the perfect way…
Remaining to-do’s are:
- Finishing rain light
- Wheel nuts
- Finishing wheels
- Cover internal aero with carbon structure
- Fitting pre-manufactured items (wind screen, top camera, antenna, pitot-tube)
A few pictures from the engine cover production:
And a few of the finished engine cover.
Some more of the internal aero devices, barge board and starting point of the wheel manufacturing.
Lotus E21 construction report part 25
Brake ducts, wheel hubs, cockpit padding, start designing engine cover and internal aero devices.
The brake ducts/drums are pretty complex shapes, but were fun to build. They are, even if they are 2013s, actually not less complicated than 2017 brake ducts. The packaging of the whole brake ventilation stuff is impressively thight (as almost everything is on this car – but not that extreme as the 2014 upwards car generation). The rear drums feature a row of little wings to generate downforce directly at the wheel. The front ducts only feature a few vanes.
The wheel hubs are relatively simple shapes, but each consisting of 16 parts. Front and rears are almost identical.
One of the most complicated things to design and manufacture is the cockpit padding. In real-life, it is filled with a foam. My one includes a structure inside and is covered by black paper. The difficulty here is, that the cockpit opening is not to 100 per cent exact (means also not 100 per cent symmetric). So I had to design the padding not to the exact original measurements but to the model’s shape – finally it is slightly asymmetric, but it fits pretty well.
Probably the most complex part on the entire car is the engine cover. Same as the cockpit padding, its shape has to be designed to the already existing bodywork on the model. Surprisingly the first design was already pretty good. Just two prototypes had to be designed till the right shape was found.
Remaining to-do’s:
- Finishing rain light
- Wheel nuts
- Wheels
- PDRS
- Engine cover
- Internal aero
I don’t like to place another completely wrong estimated date of completion – like I’ve done in the previous post. 😂
Lotus E21 construction report part 24
Brakes, safety belts, cockpit electronics, starting cockpit padding, brake ducts and rain light.
And again two and a half moth flew by since the last post. This time again some bits are fitted to the car and the to-do list gets shorter and shorter. The completion of the car comes closer and closer. An expected finish could be at earliest by the end of April.
Remaining to-do’s:
- Finishing cockpit padding
- Finshing brake ducts
- Finishing rain light
- Finishing wheel hubs
- Wheel nuts
- Wheels
- PDRS
- Engine cover
- Internal aero
The first five bits on the list are a work of maybe two weeks. The car is looking more and more attractive from day to day. But to increase the suspens till the “roll” out (maybe better move out), there won’t be any picture of the ful car any more. Just on details. 🙂
Lotus E21 construction report part 22
Brake fluid reservoirs, exhaust pipes, fire extinguisher, radiator pipes, beer and more…
Nice progress over the last days. There’s not a lot missing any more. Main sites are front suspension, brakes, brake ducts, wheels and engine cover.
When I come to the end of a car build, I usually create a to do list with all the stuff on which is left. On this list I rate all elements with
+ which means, it’s an easy, quick and nice, simple to build element
~ which means, it’s a pretty simple element, but takes it’s time and is not that nice to manufacture
– which means, it takes a lot of time to build the element
Front suspension, cockpit padding and engine cover are the last three minus elements (maybe also the rims).
The components and assemblies, I produced during the last few days are stuff like exhaust end pipes (with their helmholtz resonater – more on that in picture caption below), fire extinguisher, brake bias lever, dashboard, roll sensor, brake fluid reservoirs, pitot tube and some electronic stuff at the front end of the chassis.
Beside all this, I created a rim instruction. So the rim design is already done.
Unfortunately I lost the drive shafts during the summer… 😦 So light delay at the rear suspension build.
At the moment, the car is at about 4000 parts.
Lotus E21 construction report part 21
More to come in the next weeks…
Design start of cockpit internals, fitting radiators and finishing rear suspension components.
As uni stuff (exams) is coming to an end slowly, I’ve a bit more time left now and car progress will speed a bit up during the next time.
Over the last few weeks, I’ve done quite a lot of (more or less) small detail work on the car. First of all, I’ve found a suitable grid for protecting my radiators (metal grid with about 1mm mesh size). After fitting this to the rad ducts, I was finally able to fix the radiators to the car. A bit of detail work is still missing there, i.e. proper sealing, pipes, etc..
The next building site was the finishing of all the rear suspension components with clear lacquer. As I don’t have a proper paint shop (room), I had to wait for acceptable outside temperatures for lacquering on our balcony.
Next point are the cockpit internals. As I have to wait a lot during finishing and mounting the rear suspension, I need a site where I can build at and not touching the car a lot. So seat is more ore less done (picture series below), steering wheel (picture series below) is well on the way and some small bits such as “dashboard” (that’s the tiny bit at the drivers right hand side with fire extinguisher and ignition button on it) or belts are missing.
There’s not too much stuff missing at the car now. Front suspension, brakes, wheels and engine cover. Nevertheless, I expect finishing the car not before middle of autumn – maybe October.
Lotus E21 construction report part 20
Summary report of December, January, February
Design start of front and rear suspension, manufacturing rear suspension and barge boards.
In December I started designing the front and rear suspension. Designing the suspension is one process, to get the suspension properly onto the car is a different step… The design of the suspension is based on the chassis/gearbox mounting points and the wheel position. The manufacturing of the rear suspension is almost done, just the pullrod is missing. The positioning of the upright relative to the chassis is one of the most essential points in the building process as it defines the position of the car above the ground in finished stage. For this reason I did a jig to position the upright correctly and connect it via the suspension arms with the chassis.
Also the barge boards are already manufactured and are awaiting the lacquering process (as well as all the suspension elements).
Lotus E21 construction report part 19
Slowest progress ever…
Redesign of cooling ducts, finishing airbox, starting with electronics design and fitting process of the radiators.
There was a little progress over the summer since the last post. My intended finishing date for the car was something about in spring 2017, but with the current progress rate it could move into the summer. 🙂 But one after the other:
- I finished the redesign of the side pod cooling ducts. I did a design, when I built the monocoque back in autumn ’13, but in spring this year they proved to have a wrong size and position to fit the radiators (collisions with floor and exhaust end pipe). So, after the redesign they look fine, but it’s still a huge challenge to manage this tight packaging. I see more problems coming when designing the engine cover. 🙂
- Quick note on the airbox: All done, lacquered, fitted and sealed. No problems at all.
- A few weeks ago, I started with the electronics design. The electronics are fitted in the side pods each below the radiators, below the drivers seat and at the front of the monocoque. The rh side pod is already filled up with just missing out the cooling duct for one of the boxes. Btw – all electronics data are free available at mclarenelectronics.com – thanks MES for that!
- At the mo, I’m fighting to get the radiators properly fitted to the ducts.
Lotus E21 construction report part 18
End of “creative break”
Finishing rear wing and start of of internal duct design. Furthermore – finishing my Bachelor degree.
As my Facebook followers might have noticed, I had something like a creative break on building my Lotus. Main reason for this is to find on uni. As I was finishing my BSc degree in Mechanical Engineering and starting my Master studies, there was a lot of stuff to execute. I guess, now in the summer month, there should be much more progress on the car than during the past few month.
Two days ago, I restarted working on my E21. The last few bits I did on the car was assembling, painting and fitting the rear wing to the car.
After removing the existing side pod cooling ducts due to non-compatible size of themselves (a design error), I started to design new one with all the given circumstances. The left cooling duct houses the water and gearbox-oil radiator, the left one engine-oil and ERS radiator. I’m still not completely sure, where the hydraulics cooler sits. Probably at the top of the monocoque below the airbox. As you will see in the pictures below, it’s a tough challenge to achieve the extremely tight packaging, especially in the area around the exhaust system and the radiators.
The airbox is a bit more complex than the previous airboxes I’ve built so far, but the design process didn’t showed any big problems.
Next things on the to-do list are finishing these ducts, than design and build all the electronics sitting in the side pods (ECU, PCU,…) and the PDRS ductings. Now let’s take a look onto the car.
Lotus E21 construction report part 17
Interim Report:
Something about Rear Crash Structure, ERS Battery, Exhaust System and Rear Wing
Pretty long time went on since my last post. Some work on uni, some work in Formula Student and a move into a new flat prohibited me working a lot on the Lotus. Nevertheless there are some news since the last report.
Where should I start? Probably it’s worth mentioning at the beginning that the gearbox is now finally fitted to the engine. This comes along with the finishing of the hydraulics pump/hydraulics system which sits on the right hand side of the engine beside/behind the oil pump.
After fitting the gearbox to the engine, I started working on the rear crash structure. Nothing very impressive or interessting to tell about it. With the fit of the rear crash to the gearbox, the car reached its full lenght of 507mm. It should actually be 508mm long, but one mm is within the acceptable tolerance (indeed it’s less than 0.2% deviation). Of course the rear crash structure is hollow to allow the fit of a working rear light. 🙂
Another work which was done within the last two month is the production and fit of the ERS-battery. Although the battery isn’t visible on the finished car, I produced a simple battery model, just as a “nice to have item”.
Next point on my (still endless long) to-do-list was the manufacturing of the exhaust manifold. Always a very demanding and not really liked work. For the first time in my modelling career, I produced an exhaust system, lacquered with a chrome spray. And it looks convincing. The system is already fitted on the car. And the packaging is stunning. I had quite a few problems to make the underbody fit to the car with the mounted exhaust manifolds.
Subsequently I started working on the rear wing. End plates and flaps are finished, DRS and beam wing are still under construction.
There are also some bad news. I had to grind off the whole cooling ducts in the side pods as they were too wide at the bottom. Coming along with this, my radiators are also worthless and need to be redesigned. Luckily radiators are not very demanding to design and build.
The car currently has about 3100 parts. About expected 2500 more to come.
At the end a nice video of the first try to fit the underbody to the chassis.