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.
Finishing Underbody and Coanda Exhaust
Finally, the underbody is finished. What happened since the last post? Beside manufacturing the Coanda exhausts, where I used a colour spray lacquer (chrome) for the first time, I added loads and loads of small features to the floor. That means stuff like skid blocks, heat shields, IR cam housings, tyre vanes, diffuser strakes, diffuser gurney, live locks, some sponsor/partner labels, reinforcement stuff, bolts, skid planks or CFRP textures.
As I mentioned, I introduced some new techniques, namely the chrome spray lacquer for the Coanda exhaust groove for example. After it initially worked flawless, it happened that I run a bit into trouble when applying the final layer of clear lacquer. On the chrome can it says, it’s not compatible with clear lacquer, but I thought, clear lacquer will just run off the chrome surface. Instead, it dissolved most of the chrome…
Another new technique was, to use a special glue for applying big-surfaced CFRP areas. Previously, if I bonded on the CFRP texture (90g/m² paper) with my usual glue, it happened that the paper started to dent. The new glue is much less aggressive and does not show this properties.
Enough blathered, here are some pics of 448 glued paper snippets:
The WordPress.com stats helper monkeys prepared a 2014 annual report for my blog.
A special year ends for me. The obvious highlight was working at Red Bull Technology, a lifetime dream got true! This experience ended up in our special vid which was produced by Siemens in cooperation with RBT. Click here to watch. In meantime I am back on uni finishing my studies in MechEng before returning to Formula 1.
In terms of building my paper cars, it was a bit more quiet than the years before. There was some progress on my Lotus, however I’m working now over 16 month on this car. The famous RB7 took me just 12 month. But there’s some light at the end of the tunnel: I expect to finish the E21 in summer.
Last but not least, my FB page has now more followers than my native village has inhabitants (that’s actually not that difficult, as we have just a bit less than 1300 inhabitants :D ).
Anyway, I want to greet all of my fans with this and wish you a happy new year and you’ll read from me in 2015.
Here’s an excerpt:
The Louvre Museum has 8.5 million visitors per year. This blog was viewed about 180,000 times in 2014. If it were an exhibit at the Louvre Museum, it would take about 8 days for that many people to see it.
With the underbody, I’m working now on (one of) the most important aerodynamic feature(s) of my Lotus. The underbody produces about 30% of the cars (negative) lift, but just a little fraction of its drag. The side of the floor is sealed by vortices, created by the barge boards at the leading edge of the floor.
Special features on the Lotus floor are the Coanda-exhaust sealed diffuser and the blown starter hole.
The Coanda exhaust, was the difference making aero feature in the seasons 2012 and 2013. The Coanda-effect describes the phenomenon of a fluid-flow, following a convex surface instead of separation of it and move along its original flow direction. In Formula 1, this effect was used, to lead the high-energy exhaust plume between the rear tyres and the floor to seal the diffuser. Some teams were able to control this tweak better than others. At the end of the 2013 season, Williams was faster by removing its Coanda system. The most effective systems were built probably by Red Bull and Lotus.
The blown starter hole is an aero tweak, to prevent flow separation at the middle area of the diffuser. There you take “good” air from the side of the car and lead it to the diffuser and exit it via the starter hole to re-energize the boundary layer. With the ban of the classic starter holes in 2014, some teams use vortex-generators to convert the air to a turbulent flow for preventing a stall.
Gearbox and Underbody Manufacturing
After finishing the Renault RS27-2013 engine, I started to design the gearbox (my usual process chain: monocoque-engine-gearbox-underbody-systems-suspension-wings-bodywork-wheels). The Lotus’ gearbox is a bit of a pain to do as they are one of the last teams, not to use a Carbon composite housing. It’s a cast Titanium structure. Williams is the second team in the grid not using a Carbon gearbox (Aluminium). To rebuild metal structures from paper is always very difficult. Anyway, it’s (almost) done and I can be pretty satisfied with it.
The whole suspension stuff is located within the gearbox. That’s a trend which appeared about three years ago. Before, most of the suspension stuff (dampers, springs) was mounted outside the housing beside the gear cluster. With the aero development over the last years, the teams started to locate all this stuff inside the housing in front of the gears, to get a tighter ass. I don’t know, if I’ll add all this stuff inside the gearbox. I will do the ARB and the drive shaft definitely but I won’t do the gears.
This week I also started with the underbody design.
Over the last few weeks I, was working on the RS27 Renault engine. In the meantime it’s all done except the fitting bolts to the chassis. The engine has something around 700 parts in its final stage.
The engine is much more detailed then the one at the RB7. As you might know, the Lotus E21 and the Red Bull RB7 have the same engines with just a few minor visible improvements. At the RB7 I haven’t built a throttle hydraulic unit or the injection system was much more trivial. Also the engine block as well as the pick-up points for the monocoque and the gearbox should be a bit more stiff and rigid. All in all, an expected overall improvement of the engine.
News on the Engine Manufacturing
This is more a tiny update just to keep the blog rollin. There will be more progress on the car when I’m back to uni finishing my mechanical engineering degree at the beginning of October. So look forward to that time!
As the engine is a fully stressed member of the car it’s very important to get a stiff and reliable connection between the engine and the monocoque as well as the gearbox. These connections I achieve with steel pins of 1.2mm diameter. On the real cars, the regulations dictates six M12 bolts to fix the engine to the monocoque as well as to the gearbox. Regulations around the engine cover bore, distance between cylinder axes, crankshaft height, bank angle, CoG, etc. With a bit of understanding of some engineering subjects and this data, it’s not that difficult to redesigned this engine from paper. It’s actually a bit like reverse engineering.