Lotus E21 construction report part 7

Side Pod and Airbox Manufacturing

Nice progress in the past few weeks. After bonding together the two halfs of the monocoque I immediately started designing the side pods. Always one of the most challenging things. The shape of a modern F1 side pod is such a masterpiece this days that it’s really hard to model it from paper. As the proper pods surface is bent in two directions and paper is basically not drapable and just able to be bent in one direction, I had to simplify the shape to a developable, just in one direction bent surface. It actually worked out well with the usual problems at this stage.

Second big point of progess is the airbox. The E21’s airbox is the most car typical airbox since the Merc 2010/11 fin style airbox. The two PDRS (Passive Drag Reduction System) floppy ears were a bit of a pain to do and the right hand one did not got perfect, but it’s acceptable. This is also my very first airbox, I did with full details like roll hoop inside, profiled leading edge and so on. The car will propably get a bit too high (it’s already very close to the 950mm limit). I will propably measure it at RBT with a more adequate measuring tool than a set square.

Another huge improvement is the surface finishing of the car by sanding every single surface up to 1500 sand paper. This will help strongly during the paint process. The paint process itself will be 2 stepped. With a first stage lacquering of all the painted (means red’n’black surface with the sponsor labels on it) surface by approximately 7 or 8 layers and second stage will be with all aditional features like bodywork fixing flange, carbon fibre texture, etc.

Quick forecast over the next weeks. On 28th of Jan, RB10 will be launched. Hope it’s as good as the 9 end season car. 🙂 I expect finishing off the whole stuff on the monocoque next weekend to get started 1st stage lacquering the car. And starting parallel with the engine, which shouldn’t be that a big challenge as I have already built the same one for the RB7 and have seen the engine in flesh now for many (very many) times – but didn’t took any drawings, sketches, dimensions or anything else with me. Just the stuff which I was able to memorize in my head.


The 5 stages of the side pod shape. Top left was the initially calculated shape. The next ones are all refined shapes by using my side pod jig to evaluate the perfect shape. Was a very challenging task, but I brought it to a very satisfying level.


My side pod jigs. The left hand one is for evaluating the best shape and the right hand one is/was the bond on jig for forcing the pod into the right shape during bonding on the car.


Side pod during bonding process. There were a few stages to get it finished. I also applied a glue film on the inside of the pod to give it a bit more stiffness.


First airbox test. Height check and so on. The fairing between the air inlet and the monocoque went thru the same process as the side pods.


Airbox with seperated roll hoop. I guess, what means that  I don’t know, that Lotus is using a carbon roll hoop. Even if I know that f.e. STR or FI are using Aluminium ones.


Bonded in roll hoop. It was a bit difficult in the end to get access to the (later bonded on)PDRS inlets.


Moulding of the PDRS inlet. The negative mould tool is from full cardboard and sanded into right shape.


Chassis at it’s current stage. As you can see, the first sponsor logos are already fitted. Airbox is bonded on and looking quite good.


Rear view of the car. The internal ducting of the airbox will be a bit challenging. But that’s nothing to worry about this time. That’s the problem of March or so.


Rear end of the monocoque. It’s looking really good now. I’m very satisfied with most of my work. Note the nice louvres beside the impact structure beside the drivers head. They are there for helping ventilation of the engine/radiator bay.


The nice vanes and winglets on top of the side pod. Note the nice moulded top edge of the vanes. They are sanded up to 1500 sand paper to a almost perfect shape (rounded edges, ball shaped front corners).


One of the few differences between the real car and my model (apart from the size) is my logo. There are two reasons for it: I decided to label now all my cars with at least one of my logos. Second reason, almost more important, I can hide the cutting edge between the side pod and the actual (structural) chassis. Nice turn I would say.


And a bit of fun at the end. It’s not going on so seriously during my car build all time. I might not missunderstood the sense of an airbox, but that’s definitely assembled in the wrong position.


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About paulsf1

My name is Paul Bischof. I’m a student in mechanical engineering at the Technical University of Graz in Austria, expected finishing in February 2016. Since I was eight years old, I am building model planes out of paperboard. Since 2004 I scratch (that means building without an assembling set) Formula 1 and sportscars in 1:10th scale. The average time I need for such a car is around 400 to 700 hours within 4 to 8 months. One car has around 3500 up to 5000 single components. On this blog, you can take a look on my work and later, after my studies, hopefully you can see me in Formula 1.

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