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Hey Guys,
Sorry it's been a while. I've been on the road swamped with work.
Just a quick reminder I'll be at PRI in Indianapolis this week at Booth #137. We are also running our lap time simulation 101 seminar as well in room 201. If your based in the US I'm looking forward to seeing you all there.
In the mean time I have some food for thought for you all. Recently I have been reading about the life of Col John Boyd. He is the father of Energy Management methodology for fighter aircraft and some have called him the Father of the F-15 and F-16. One of his greatest contribution was the specific power equation. This is,
Ps = V*(T-D)/W
Where
Ps = Specific power (m/s)
V = Vehicle velocity (m/s)
T = Thrust or applied longitudinal forces (N)
D = Drag (N)
W = Weight of the vehicle (N)
Anyway I have a little twister for you all. Why is this so significant and for those of you how choose to accept this mission see if you can apply it to an analysis of a FSAE car.
See you at PRI guys.
All the Best
Danny Nowlan
Director
ChassisSim Technologies
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I'll give this a shot! :)
It's so significant because in air combat if you have a higher specific power you can out manoeuvre your opponent whether that be in a straight line or in turns. So you play to your strengths, if you have higher specific power in a turn and low specific power in a climb (compared to them) you engage in a turning battle rather than trying to out climb them because you have a greater chance of victory in that situation. The same applies to two cars battling on track (or against a stop watch).
It can be applied to FSAE in all cases, in fact, it's probably an interesting thing to compare between cars, acceleration is simpler because you can estimate rough drag co-efficients and frontal areas for the cars and the forward thrust based on engine data, weight can come from something like racecar engineering.
Cornering is a little more tricky but i think you could apply it still by making some approximations. Maybe consider all cars cornering at 1g, find Fy and Fz forces, then effective mu values and compare to tyre data peaks. Extrapolate out what your peak Fy values could be, assume these values, calculate cornering g and then this is your T value in the equation where your 1g situation is the D value. Not quite sure how the Velocity would factor in but that's just an idea from me.
It's probably all wrong :) but i think if i understand it correctly you can still apply it to all FSAE scenarios (straight line or cornering).
Certainly worth thinking about in any case!
Christian
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Christian,
My apologies for the delay on this. I've just been hammered on a few things.
Your observations are spot on. The only thing I would add to this is that specific excess power applies everywhere through out the flight continuum. The holy grail of fighter design is to be able to pull maximum g while losing minimum energy. The achilles heel of the current generation of western fighters such as the F-15 and F-16 while they can pull high sustained energy to do so they have the after burners plugged in making it a nice juicy target for an IR missile. It's not that often that I'll mix what I do professional to what I do privately but here is a video of the SAAB Gripen that illustrates the holy grail,
http://youtu.be/t2PPS_g3Yvw
Note for half the flight it's pulling high g with the afterburner off.
At the other end of the spectrum is the F-35 Joint strike fighter
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I'd also add that any power/energy calculations can be used, after removing the aero component, as an input to a tyre thermal model.
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Hey Guys,
First things first I trust everyone had a great Christmas and a Happy New year. I also trust you are raring to go on your new projects.
I've had a few requests for the presentation that I gave at the Professional Motorsport World Expo in Cologne/Germany on November 15 2014. I figured I could do one better. Here is the tutorial/episode of Dan's Vehicle Dynamics Corner,
http://www.chassissim.com/blog/chass...4-presentation
Enjoy
All the Best
Danny Nowlan
Director
ChassisSim Technologies
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Hey Guys,
I've just posted this video on the Shaker rig toolbox,
http://www.chassissim.com/blog/chass...er-rig-toolbox
It's a really powerful tool for understanding the frequency behaviour of the car. It's also been used to tune mechanical grip in applications such as IndyCar, FIA GT and V8 Supercars hence why it would be a useful tool for everyone to consider.
Enjoy
Danny Nowlan
Director
ChassisSim Technologies
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Hey Guys,
Some exciting news for everyone. We are know offering unlimited use of ChassisSim Online per month. You can find out more here,
http://www.chassissim.com/blog/chass...imulation-tool
Obviously I have quoted professional prices. However if you guys want to make use of this (in particular the shaker rig toolbox we discussed last week is part of ChassisSim Elite Online) then get into contact with me and I'm sure we can work something out.
Enjoy Guys
All the Best
Danny Nowlan
Director
ChassisSim Technologies
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Hey Guys,
From tuning in to some of the discussions over the last couple of weeks this is worth another look,
http://www.chassissim.com/blog/chass...-do-what-we-do
It gives a background of why ChassisSim went down the road it did. Some good food for thought.
Enjoy
Danny Nowlan
Director
ChassisSim Technologies
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Hey Guys,
On March 3 2015 I ran a webinar for Altair Engineering on how to use ChassisSim for both automotive and motorsport use. Here is the link for the recording,
http://www.chassissim.com/blog/chass...ing-chassissim
I used a couple of case studies that showed how ChassisSim can be used in road car design. In particular I covered suspension geometry changes using the lap time simulation.
I also touched upon the shaker rig toolbox and track replay simulation. All important elements that can apply to Formula SAE.
Enjoy
Danny Nowlan
Director
ChassisSim Technologies
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Hey Guys,
One of the questions I get asked a lot is can ChassisSim be used on a FSAE car? The answer is a big yes and this latest episode of Dan's Vehicle Dynamics Corner shows you how,
http://www.chassissim.com/blog/chass...ormula-student
I should also add that everything here is not theory. ChassisSim has been used in anger in FSAE. Some valuable lessons have been learned and it would only be appropriate to share
it with everyone so you can all get the benefit in using a tool like ChassisSim.
Enjoy.
All the Best
Danny Nowlan
Director
ChassisSim Technologies
