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Guest Komodo

New Boy On The Block

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Guest Komodo

Doing some theory work today on the engine, I noticed that this design completes one stroke in 60 degrees of output shaft rotation, as opposed to 180 degrees in a conventional crankshaft equipped vehicle. This basically means that for every 720 degrees a conventional engine would turn to complete one full four stroke cycle, this design would have completed 3 power strokes. Given that the mean piston speed will remain somwhere around that of a conventional engine at around 20m/s, this would mean the engine would idle at around 300rpm, and reach it rev limit at around 3000rpm, however it would still sound like it was running normal speed. (Wouldn't want it sounding like a diesel now would we...:lol:)

 

Based on this, I adapted some theoretical engine performance equations to fit, and the results I got were quite impressive. For a naturally aspirated 1.5 litre engine of this design, it would be packing around 240bhp at 3000rpm (6000 conventional)

 

Thats without taking into account the extra efficiency gained from using the crankless design, which should add around another 25%.

 

Of course this is all purely theoretical, but promising none the less.

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Guest Komodo

A few further calculations based ona turbocharged engine, using a light pressure 0.4bar turbo, output is around 295bhp, and using a larger 0.8 bar turbo, the graph is showing an estimated output of over 400bhp. From 1500cc, and without being highly stressed!

 

I'm going to have to get some prices on having the components made, I want one of these engines in my car!

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Guest Komodo

Some pictures of the new suspension set up, with what can almost be recognised as proper geometry.

post-17737-1202924820.jpg

post-17737-1202924896.jpg

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Guest kaiza

this stuff is awesome. we just finished working on CF body panels for the engineering dept. FSAE car last year and that was a tough job in itself. whats the process for fabbing the CF chassis? are the tubes precut and then joined with matting?

 

as a hint (if you're not doing this already): although i don't understand chassis design, i took the engineers SW file and redid it as weldments - it took the file down from 30+mb to 5mb.

 

just a couple of questions -

 

1) are you doing an engineering degree?

 

2) how hard is it to design a car from the ground up? i'm toying with the idea for my major project this year - thing is i don't know a whole lot about cars and how they go together, but i'm willing to put in the hours to learn because i can't get the idea out of my head!

 

after seeing the engineers attempt to build a car i'm a bit concerned about taking on a project like this myself, but i don't have any intention of actually building the car i design. im definitely going to read up on those books superbad mentioned - do you know any other good references on car design fundamentals?

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Guest Komodo

Yes I am already using the weldments feature to design the tubeframe design. As for fabbing, I have no idea at present to be honest!

 

I am doing an engineering HND, although I have been told my progress is somewhat above what is expected of HND students.

 

I wouldn't recommend taking a project like this on unless you are competent with the CAD software you use. A classmate is trying to do a similar chassis with less understanding of solidworks and his progress is substaintially slower. If you have a good grasp of modelling and a good fundamental knowledge of chassis/engines then there is no reason not to give it a go, be prepared to put in the time to do it. Bare in mind that I spend on average 4 hours a day on this. That might not sound a lot, but juggling that in between a 36 hour uni shedule, 25 hour work shedule plus socialising/sleeping time, and it takes up a fair amount of my free time!

 

I have been advised that ideally I should have designed the suspension first, and the chassis should come last, ideally to tie everything else together. I do agree with this method wholeheartedly, but since I have no intention of building the thing at present it doesnt really matter. The suspension was deisgned using some basic theory taken from some old suspension books form the uni library.

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Guest Komodo

Got one of my cylinder heads back from the rapid prototyping machine today. The printer is about 4 years old and basic to say the least, the surface finish says it all. Still, it was a nice way to spend £100 of uni money making my drawings into 3d reality...

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Guest Komodo

I done a more detailed check of the new suspension geometry today, most of it looks to be quite good for a rough guess, a few things will need to be changed though.

 

 

Here is the front setup. Everything is lined up despite the disparity between the instant centre distances. (Far left and right bottom points)

 

Static camber at 2.9deg should be about right for a race/track car, but this will need further analysis to set correctl yto compensate for changes under bump and rebound.

 

Scrub radius is too mkuch at present at 132.34mm, this is because the hubs are not correctly mated to the wheels. I will be looking to bring this down to around 60mm when the wheels are aligned properly. This should provide adequate feedback through the wheel without causing unnessasrily heavy steering.

 

Rollcentre is 32.5mm below the ground. This is good, I can't remember the justification as to why at the moment though.

post-17737-1204746883.jpg

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Guest Komodo

Rear suspension has the same issue as the front with regards to scrub radius. Other than that my rough sketch doesn't appear to have turned out too badly.

 

Rear roll centre is located 11.16mm above ground now. Being higher at the rear it is closer to the CoG hieght, which as a result reduces the torque moment under cornering.

post-17737-1204747620.jpg

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Guest Komodo

The roll axis can now be drawn between the front and rear roll centres. It;s is shown here as the dashed line that intersects the ground plane.

 

This is as far as I have got so far, and to be honest, my module doesn't require that I go any further, although I may continue at my own pace as by drawing these models I learn so much about chassis design and suspension behaviour!

post-17737-1204747840.jpg

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Guest Komodo

Today, deprived of sleep after last night storm giving my poor excuse for patios doors a battering, I thought it put my delusion to use and attempt some bodywork. Have little success in finding any kind of useful walkthrough tutorials on the subject, I simply made it up as I went along. It's a mess at the end of the day, but it can be recognised as a car now at least!

 

First is the early model, ever so slightly crude, but it got me the shape I was aiming for to progress on from...

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Guest Komodo

I'll add the other pictures tomorrow, 15 minutes to upload a single file at 2.30am is beyond a joke!

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