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.

Rear Crash Structure

Finished rear crash structure.

Gear Box with Rear Crash

Rear crash structure fitted to the gear box.

ERS Battery

ERS battery installed to the car. The battery will disappear after fitting the underbody.

Exhaust Manifolds unpainted

The raw and unpainted exhaust manifolds. Each pipe consists out of a steel wire as the core element wrapped with some layers of paper.

Exhaust Manifolds painted

Painting process of the rh exhaust manifolds.

Exhaust Manifold

The finished rh side exhaust manifold.

Car from felow

The engine area from below with fitted exhaust manifolds.

RH Exhaust Manifold

Rh side exhaust manifold.

LH Exhaust Manifold

Lh side exhaust manifold. There is a heat shield clearly visible to protect the power steering hydraulic line.

Unterbody

The underbody is waiting for getting fitted to the car.

Exhaust Manifold fitted

The lh side exhaust manifold with the fitted underbody. The packaging is extremely neat.

RWEP internal Structure

The RWEP internal structure. It’s a bit more complex as it looks from the outside. Each endplate consists from almost 40 parts.

RWEPs

RWEP vanes.

RW

The rear wing in its current state.

Cooling Ducts

The destroyed cooling ducts…

At the end a nice video of the first try to fit the underbody to the chassis.

 

Lotus E21 construction report part 16

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:

Floor Structure

That’s the floor structure shortly before getting “carbon fibred”. The white stuff you can see is mainly some reinforcement structure. I tried to rebuild the structures as true to the original as possible. Some of the white stuff at the front is also just a 3d radius.

Coanda Exhaust Painting

That’s my first try with coloured lacquer. To paint the Coanda exhaust grooves with chrome seemed to be a good idea. It looked great as you can see in the next picture. But unfortunately the chrome lacquer and the final clear lacquer aren’t good friends…

Coanda Exhaust Panel

The Coanda exhaust panel after painting. The chrome is pretty soft, so you can see my finger print at the end of the Coanda groove. I did a little bit of a hardness/dryness test.

Floor Stay

The famous Lotus floor stay. Wonderful shape! Teams racked their brains to find out, why the Lotus stay was shaped like this. It stayed just for the 2013 season in this configuration.

Floor Front Corner

The floor front corner with its weird shape. The strange bulge coming from the inside of the car houses the lower crash elements.

Blown Starter Hole Intake

The blown starter hole air intake below the Coanda exhaust. Red Bull introduced this idea already in 2012. Lotus and Caterham followed in 2013.

Coanda Exhaust Panel Inside

The Coanda exhaust panel from the inside. Not very spectacular, but you  can see the port for the exhaust manifold, the whole heat shielding and some live locks (i.e. kind of bolts) to fix the surrounding bodywork.

Tyre Vanes

The tyre vanes which help to lead the exhaust plume towards the gap between the tyres and the floor. You can also see the IR sensor housing (outside of the main tyre vane) which looks at the rear tyre to log their temperature development.

Floor Rear

The rear of the floor with the diffuser. Very good visible is the diffuser gurney which helps to prevent a stall on the diffuser underside. With the new restriction of the diffuser height mid of 2011, teams switched from the classic diffuser gurney to a slotted gurney which is more like a little wing at the top of the diffuser. Another tweak to handle the new diffuser height restriction of 125mm (it’s actually not new any more in 2013/14), was to expand more in width. So, the diffuser rise starts with a width of just about 700mm and expands to the rear to the full 1000mm (or slightly below).

Diffuser

The diffuser viewed from the rear. That’s a very good view to see why it’s called “slotted gurney”. It’s not actually a gurney, but a little wing with a gap to the top surface of the diffuser. Often this wing is also provided with a little gurney itself.

Floor Underside

The Underbody from below. You can see all the fixing bolts where the floor is fixed to the chassis and the engine. Notice the different wear of the three skid block pieces.

Skid Block Front

As already visible at the top picture, the Skid Block is splitted in three pieces (permitted by the regulations). This shows the front piece which is fitted to the T-Tray and is therefore the element which mostly slides on the track.

Diffuser

A good view on the important heat shields which prevent floor damage due to hot exhaust gases. The shedding edge you can see is the area, where the exhaust plume enters the floors underside. Also notice the different CFRP structures at the diffuser.

Car

The car in current state. Still no end in sight, but slowly you can imagine whereabouts this project will lead…

2014 in review

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.

Cheers, Paul!

Signature

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.

Click here to see the complete report.

Lotus E21 construction report part 15

Underbody Manufacturing

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.

Underbody

The underbody in current state viewed from the top. You can see very good, how narrow the rear of the car is. The two ducts left and right are the ducts to blow the starter hole. Above this ducts, the exhaust will exit the bodywork in its Coanda-groove. More on this later.

Diffuser

Trailing edge of the diffuser. Because of the special shape, the rear of the underbody is a bit deformed due to internal stresses. But with adding another layer of paper (the top one), this should be solved…

Underbody

The leading edge of the underbody. Weird stuff…

Underbody

A better view on the blown starter hole ducts. You can clearly see how it works. There’s an awful lot of air coming from the side of the car. I expect just a very small percentage of this air effectively find its way thru the starter hole. The two cutouts/dents which you can see at the inside halfaway thru the duct are there for the pullrods.

Underbody

Nice rear view where you can see very good the deformed sides. You also can see the exits of this two ducts, which are beside the gearbox later on the car. This ducts end about at the rear axle center line.

Barge Boards

The barge boards which produce the vortex at the leading edge of the floor. This are far the most comlex boards I’ve ever seen in F1. They consist from four airfoils with the last two ones splitted. Lotus used them just in the 2013 season. In 2014 they returned to a more conservative design.

Rear

Underbody pre-fitted to the car. You see the amazing packaging around the gearbox. Here you can see again the cutout for the pullrod. At the moment you can see the rocker there.

Car

This will be a tough challenge to make the underbody fit perfectly to the car…

Lotus E21 construction report part 14

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.

Gearbox

Front bulkhead of the gearbox. The starting point of the design. You can clearly see the six pick up points to mount the gearbox to the engine. At the real car, this is realized by six M12 studs.

Gearbox

First attempt for the basic structure. The shape is pretty trivial. I just needed one try to get it done. Very important is the integration of the studs into the structure. They have to pick up the whole load. It’s the first gearbox, where I do it this way. My previous gearboxes were just bonded to the rear face of the engine. The advantage here is a much higher stiffness between the engine and gearbox.

Gearbox

The first try to fit the gearbox to the car. Even without glue, the connection is so stiff, that I can carry the car just by holding it on the gearbox.

Gearbox

Finished gearbox housing mounted to the car and pre fitted underbody.

Gearbox

From the top you can see how tiny the gearbox is. There’s loads of space between the wheels and the gearbox for aero tweaks.

Gearbox

Gearbox removed from the engine.

Gearbox

Rh side of the gearbox housing. The hole that you can see at the lower front of the housing is for the ARB. The top front one for adjusting the heave damper. You can also see the angled rocker. At the rear you can see the fixing point for the rear crash structure.

Gearbox

Lh side of the gearbox housing. At the rear below the final drive, the oil pump will be located.

Gearbox

My gearbox drawing. I had to stretch the gearbox by about 3mm compared to the drawing to reach the correct whelbase.

Gearbox

With the gearbox mounted, the cars current length is at 458mm. With the rear crash structure attached it will reach its full length of 508mm.

Gearbox

Top view of the car with mounted gearbox.

Underbody

Current state of the underbody. There’s still a lot of work left to do. Note the blown starter hole in the diffuser area. That’s to prohibit a flow separation. More on this later on during the build of the underbody.

Lotus E21 construction report part 13

Engine Manufacturing

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.

Renault RS27

The Renault RS27 engine in its current state, viewed from the right front. You can see the carbon fibre moulded oil tank very well. There is a cutout in the rear wall of the monocoque to accommodate the oil tank between the chassis (fuel tank) and the engine. The oil itself is cooled by the radiator in the rh side pod (temp. approx 90°C – 95°C).

Renault RS27

The part of the injection system which is located within the engine manifold. You can see the frame where the injectors sit on which inject the fuel under a pressure of 100bar into the inlet cones. The current 2014 F1 engines have direct injection with a pressure of 500bar. Direct injection saves fuel compared to a conventional injection system.

Renault RS27

A view into the engine manifold with mounted injection system. I took some design borrowings for the injectors from older Renault engines as there were no pictures available from the RS27. On a YouTube video, published by Renault Sports F1, you can see a few bits of the system of the 2011 engine (on the test bench).

Renault RS27

During the transportation back to Graz, the oil filler came off the oiltank (top of the tank). I’ll redo it before fitting the engine to the car. The two lines you can see coming from the inside of the V to the rh side of the engine are for the throttle control and will lead into the ECU (Engine Control Unit).

Renault RS27

The RS27 engine from the top. The inlet manifold, which is fed by the airbox, is a CFRP item with a heat protection layer on the outside to prevent the air for the combustion process getting hot due to the engine/radiator heat.

Renault RS27

Cam(shaft) cover at the rh side. I’m not 100% sure what this line is for, which leads into the manifold. But I expect it to be the supply for the pneumatic valves. Even if they should work passively, I’m sure, there are some losses during a race and you have to refill the chambers of the valves.

Renault RS27

Lh side cam cover. Same as the rh one, just with the additional water inlet.

Renault RS27

Rear view of the engine. You can see a part of the hydraulic throttle system. The two hyd connectors which supply the unit are missing. You can see also the two upper bolts to fit the gearbox. The four other bolts (which are required by the regulations) will probably be fixed to the gearbox.

Renault RS27

Rh side of the engine with the oil pumps being visible at the bottom of the engine. There will also be the hydraulic pump of the rh side of the engine beside the oil pumps. But I will not mount it before fitted the gearbox as I think, the hyds pump is fixed to the gearbox.

Renault RS27

Lh side of the engine. You can see the water pump (front) and the alternator (back). I’ll have to replace the alternator with a MGU I guess.

Renault RS27 with chassis

The Renault RS27 pre assembled to the chassis. Again you can see how small such an engine is. The dimensions length x with x height are 49.8mm x 71.7mm x 54.1mm.

Renault RS27 with chassis

Renault RS27 with chassis.

Lotus E21 construction report part 12

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.

Monocoque, Radiators, Engine

Current state of the car. At the left hand side of the car, you can see the water cooler and gearbox oil radiator, rh side is the engine oil as well as the KERS radiator. Between the engine and the Monocoque you can see the engine oil tank which catches about four litres of oil.

Engine

It’s again and again very impressive, how tiny the V8 engines were. Not to speak from the current downsized V6s. In the Le mans cars, the engines are often equipped with an additional brace as they are too weak to work as a fully stressed member.

Engine

Rear upper engine stud. This stud is fully integrated into the engine structure and picks up the upper gearbox mounting point.

Engine

Engine manifold. Fuel injection system and air filter will sit in here in a few weeks time.

Engine

The water pump at the lh side of the engine. There is another ancillary item going to sit behind the water pump.

Engine

The oil pump on the lower rh side of the engine. Beside the oil pump, the hydraulic pump/manifold is placed. It’s not designed yet. The hydraulic system powers throttle, clutch, gearchange, differential, power steering and DRS actuator. The hydraulic linked suspension is a completely independent system.

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