Regarding Dynamic Loading due to piston

[vishnumohan95]

Hello there. I am a powertrain member of TeamKART, IIT Kharagpur.
We have recently finished the designing part of our next car. We calculated the centre of mass of our KTM 390 engine and aligned it with the midplane of our chassis. We have also ensured that the centre of mass of the remaining components roughly lie at the mid plane of the chassis. However, we have not taken into consideration the dynamic forces produced by the piston as we didn’t know much about the internal engine balancing. The centreline of the cylinder is at a 4cm distance from the chassis midplane.

Is there any team who has tried this? Will this design face any problems in the technical scrutiny? Any constructive comments regarding the design are welcome.

1309

[DougMilliken]

...dynamic forces produced by the piston...
Reminds me of the problem of the unbalanced handkerchief, as addressed by the Schnorcedes team at "The Grand Prix of Gibraltar".
This scene starts at about 7:00 https://www.youtube.com/watch?v=mfchbxFoaOY and goes to about 11:30 (don't miss the end).

[Will M]

Hi there vishnumohan95, welcome to the forum!
There are a lot of great resources here so please look around.
You might find a thread on this exact topic!
There are also a lot of experienced people here.
They can be rude but have valuable knowledge.
Try to look past their rudeness and focus on the engineering.

Every car will face scrutiny at the completion for The design judging.
The most important thing is to be able to explain your engineering process.
You must understand the benefits and detriments of your your design.
If you can explain the trade offs then you will do well.
If you just copy an existing design you still must explain the engineering process.
A well rationalized compromise may do better than a copy.

For the specifics of you design be ready with estimates of the forces from the engine on the car from the changes in RPM.
Maybe it is small and will not make a difference.
Maybe it is large and requires counter measures.
Make a free body diagram for this.
Also do some search on drag race cars.
Their engines create such torque so as to significantly unload one rear tire.

I hope this helps and again welcome to the forum!

William

(sorry for any spelling mistakes. It is hard to type in a taxi!)

[MCoach]

This reminds me of all of the threads asking about the negative aero effect of engine exhaust tips pointing forward.


vishnumohan95, I think this may be a non-issue. How many kW of power does you engine produce?

[vishnumohan95]

Hello MCoach,
We use KTM Duke 390 single cylinder engine. It roughly produces an output of 25kW.

[MCoach]

Hello MCoach,
We use KTM Duke 390 single cylinder engine. It roughly produces an output of 25kW.

I would see it as non-issue unless you can produce a measured result showing a significant difference it makes in terms of vehicle set-up or design.
Would this effect cause you have a different spring choice from right to left? Would this cause you to choose 5% anti-squat geometry over 8% from your analysis without this effect?



Do not lose focus of the creature which produces the feather you've studied so close.