Bubba Got a Boring Bar | WeaponsMan

Bubba Got a Boring Bar | WeaponsMan.

This is an amazing insight.  Reducing the weight of guns. This article has introduced a new term (as most Americans do) and its called ‘Skeletonizing’. The article mentions that most gun are made using light weight steel or aluminium components.  Reducing weight is probably not on the highest priority.  Yet there is a market for them simply because you would be carrying it all day in the battlefield while evading sniper shots.  What this means is that there is always a benefit to make things lighter.

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Flow Simulated Tests

I have found a nifty free program that could do a flow simulation and show it graphically as a video clip in .avi format.  It is called Flow Illustrator.  It is not accurate to replace a full blown Computational Fluid Dynamics software but it is free.  You will need to do your own model.  This is simply done by using a side view of the model.  You can do this by using an existing picture with non essential details such as background and people deleted.  I use Microsoft paint to edit my picture.  Please note that it is advisable for you to use the CUT function using SELECTION.  Once the image you need is cut from the original, you crop the rest leaving with a totally white background.  You can upload the picture and set three (3) variables; Reynolds number, time between frames and video length in seconds.  I only change the setting for video length.  If you want to do comparison of flow between two designs, you need to have the picture in the exact dimensions.  The value of the Reynold’s number will be shown on the video.

You can see the comparison video on this link.

A screen capture of the comparison is shown below

SNR3 with Deflector

Simulated flow on Satria Neon with Deflector

r3stock

Simulated Flow over Satria Neo with Standard Spoiler

Notice I have cut out the wheels to indicate flow of air under the floorpan.  Green coloured areas indicate high pressure/low velocity and Red indicates low pressure/high velocity.  The comparison helps to show that the original design with standard spoiler has a bigger wake left in the trail of the car.  The one with the deflector has a smaller wake as the height of the turbulence is reduced.

If you do another comparison with a sedan design, you would see that the wake is about the height of the boot.  The deflector now looks like what we intended it to be.  It is to reduce the wake by delaying air separation from the hatch.  This partly answer the previous question of why the Fuel Consumption curve is not logarithmic.  The deflector has therefore made the car more aerodynamic.  It makes it easier to cut through the air.  I would not be surprised if it has reduced the Cd value of the car.

Making the car aerodynamic has the added bonus of reducing drag and obtain faster acceleration and top speed.

Adjustable Spoilers Part 1

I have mentioned in some random postings on the internet of the need to have malleable aerodynamic surfaces to reduce drag in different driving conditions.  In fact Autospeed.com has mentioned this as a stumbling block in automotive design advances.  Articles such as this one has given me ideas about changing the effect of rear roof spoilers from just providing small down-force and drag to actually help reducing wakes.

Good spoilers

Spoilers to reduce wake meant for big profile vehicles such as MPVs and SUVs

 

Since I mentioned about Arduino in my last post, I have actually bought one from RS Online Catalog.  I have the Starter Kit for Arduino Uno which comes with lots of bits and pieces.  I have mentioned that I had never dealt with electronics before.  The most I have done is fondled with DC circuitry.  Hence an order was given and the money was pumped into the Open Source community. I hope they use it well.  I received the box and was amazed at the amount of things Malaysian Ringgit could buy.  When I say ‘the amount of things’ it is not about the quantity of odds and ends.  Its about reusable components.  This Starter Kit is amazing in terms of what things you can make with it.

It took me yet a few more days before I started fiddling with it.  I blame it on my age.  A child would rummage through it without a second thought.  A teenager would plug it in first and jump for joy to see the yellow LED lit up.  A twenty year old would skip all the pages and build it up with the first drawing.  I am 45 years of age.  I read every single page of the manual and tutorial first.   Even then, I went to the website Arduino.cc to have a look at the specifications of the blue thingy that i a permanent resident at the side of my bed.  Its entirely ok.  My wife has her TV/Android phone/ Android Tablet as companion.
I have this.

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It started with this

What that thing does is move the servo using a potentiometer.  The LCD shows the angle in degrees from the readout of the servo.  The LCD is meant as part of the development of what I intend to build.  I would use it to adjust the angle while doing testing.  I will adjust the angle of deflection and see the effect on the fuel consumption via the on board FC computer.

Yes that servo is tiny and has a stall torque in oz-in.  It came with the starter kit.  About mid of March I bought a bigger servo from MyDuino.com  and its a markedly bigger in size and now I have something that pulls in kg-cm.  The intention is to move a piece of aerodynamic surface as part of my car’s rear spoiler.  I have calculated that for a 1m span, the wind force acting on it at 200km/h would total 1.4Nm2.

A discussion on these sort of spoiler is well documented.  I have to admit that it does not contribute much on the actual down-force required for a front engined front drive car.  In fact, when looking at the profile, it would also provide less drag.  Quite simply when the designers made this, it was never meant to provide much effect other than cosmetics and form rather than function.  Proton now understands to sell it, it need to look nice.  Unfortunately.  In essence, the design and flow of the spoiler is very fluid.  This suggest a high amount of design work was invested in this one piece of fiber.  There is no argument that this part actually sells more of the car than any other body kit.  It is therefore wise to preserve the design as much as I possibly can.

 

Secondary Intake Pt 2

It is hard to write down the results of the test on the road.  It is hard because I have been very ecstatic about the results.  It has been two days of consecutive tests.  Repetitive results would provide an assurance that the reading was not a fluke.  And that is exactly what has happened.  The first day and second day results were the same.

Testing method was by observing the onboard Fuel Consumption meter, having the car maintaining 80km/h speed.   Location of tests were two; from Putrajaya to LDP Toll on my drive to work and from USJ exit to

PutrajayaTest 3 results Toll on the Elite Highway.  After two consecutive days, we can safely say that both readings were the same.

Putrajaya to LDP: 4.0l/100km

USJ to Putrajaya: 3.5l/100km

I use two different route as my daily travel plan on weekdays.  Therefore the test would provide me estimates on the effect of the modification towards my daily travel costs.  The second day of tests, I had become impatient on the way I should do these tests.  So on the return trip.  I did two separate tests; one at 70km/h and the other at 80km/h.  I had video taken to show that the consumption was 3.3l/100km when driven at 70.  Which is even more fuel savings.
Some friends were concerned about the fuel savings on actual performance.  I cannot say if there was any negative performance effect as I wanted to do this mod for Economy and not to increase power.  But I must say that the question has intrigued me. I look forward to making my own video stand to clamp on the seat headrest.  This will provide datalogging capabilities.

Debunking Myths

Some people I know do not want to take the reading seriously as many doubt the accuracy of the onboard computer.  Some would want me to do the ‘Fill up full at the Tank’ method.   When we take measurements, we need to reduce variance as much as possible to get closer to the truth.  Setting the datum at the petrol kiosk has several fundamental problems.

a) How do you know that you are actually filling up to the full?  An empty petrol tank can only be found on a car that is not running. A partial tank in reserve can contain 5 litres or less.  How much less?  We cannot possibly know.

b) When you fill up to the max, there’s two problems one is engineering wise and the other is behavioral

i)  You can never know whether a pump has delivered the correct amount of fuel you require by measuring at the fuel tank scale.  The scale of the meter is huge compared to the resolution we are trying to find out.

ii) If you are driving on full tank, then you think that this is just a game.  Someone who drives will a full tank all day is bringing with him weight that he does not need.  Carry only what you need.

They probably need to know how the FC reading works.  Its is pretty much simple.  The ECU controls the triggers to the fuel injectors.  All it needs is to count how many firing of the injectors were done since the event of the reset button press.  It multiplies the number of firings against the number of injectors, multiplies it against the flow capacity of the injectors and take the trip meter reading since button press.  The trip meter or distance measured is based on a magnetic pickup on the driven wheel which is fed directly to the ECU.

If you limit the use of the FC reading to measuring at constant speed and relatively short distance, then it is good enough.