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.

Real World Test

It came as an afterthought.  It was never my direct intention to have done what I made.  I had initially made a Secondary Intake for reducing fuel consumption of this car.   See my previous article.  Then I wanted to make the spoiler adjustable so that it can actually be useful.  This was on my previous thinking that the spoiler functioned as perceived.  That it provided down force and that if I took it out, the handling would suffer.

This then changed somehow without any premeditated intentions.  What I have right now is a combination of efficiency solutions.  The secondary intake initially showed that I could save money in the movement of the throttle.  That was fine.  Then the aerodynamics were sorted.  Never did I thought the two combined mods made significant fuel saving changes.

I did a test run yesterday for 230km in total.  This was a return trip on the North South Highway.  It was to test the Deflector at speeds above 90km/h.  It performed admirably by registering an Indicated average Fuel Consumption (FC) of less than 5.0 l/100km. You can see the YouTube video here . Yes, this means I now have a YouTube account.  Forgive me I am rather slow at 46 years old.  I have only now found the use for it.

During the same journey I made similar tests for speeds of 100, 120 and inadvertently 130km/h.  All of these test results were on solid straight roads with the AC switched on.  I plotted the values which I had observed on a spreadsheet.  I had expected a exponential curve from 100 to 130km/h.  But I could not get it.  The only time I observed a high FC is when the car was being driven at 100km/h up a 20 degree incline.

capture_11092014_004322The table is now UPDATED on 9 November 2014.

The data is based on observed data from factory standard equipment.  They are not absolute and the value is AVERAGE Fuel Consumption.  The last data if drawn to scale should be closer but it should also be higher.

A few things floated in my mind.  As engineers we are told that aerodynamic load is very much affected by speed of the object or vehicle.  This aerodynamic load increases .  Fuel consumption will increase dramatically as speed increases.  Perhaps it is too early and too easy to say that somehow with the combination of both modification, we have come to a point where the world is no longer flat.  I might need to spend more day trips to Melaka to do more tests.  One might say that these values at these speeds are insignificant as the speeds are low.  But these speeds are what normal people are driving at.  This is the whole point of doing these modifications.  It is so normal people could save money driving normally.

Should anyone ask about performance degradation; I simply did not see any.  The maximum top speed is still attainable.

Deflector Part 2

Just a quick one as I do not want to give away too much.  Finally managed to do up the fibre glass work with Chooped Mat and Roving.  The Roving is better suited to hold the surface on the edges as it is stronger.

 

Producing the top surface Needed to brace this securely on this working design.  I would not need to get a really solid grip on the production model as it will totally be fibre glass.  As it is now, wood is used as the main structural material.  I would only need this working design to make some sets of mould.  The finished product would therefore be much lighter and look nice.

Deflector mounted on car

Deflector mounted on car

Had a spin around Putrajaya.  About 45km distance.  First round registered 4.3 l/100km while the second registered 4.5l/100km.  Will keep doing test and maybe try to add more surface area on the bottom.  I am very happy as it is, there was little effort to try and clean it up.  Not even fillers and it still meets the target.  Probably I might get better results with the extension.

Deflector

This is one of those Excuse Post that tells you what I have been doing for the few months without any updates.  Its going to be just pictures.  I am contemplating registering my current work as an Intellectual Property with the Malaysian IP Office.  This does not make me backtrack on my support for Open Source inventing.  The Adjustable Spoiler is rightfully Open Source while this is not.  I shall be making an air deflector.  I need to protect the design as it is truly my own.  Its like making a spoiler from scratch.  And by showing these pictures, anybody could do it.  Therefore it still has it part in this blog with the exception that it is not really simple for me to come up with it.  I am not talking about the pencil sketches, Sketchup models and DoubleCad XT 5 that I made prior to really hands on down to the dirt work I did in the back of my house.  I am talking about the amount of work going into cutting the wooden pieces, gluing, screwing, filing and general woodwork.  Then fitting every bit and pieces onto the back of the car to make everything… well er… fit.

Deflector

Deflector and Jig

 

The main surface is made up of laminated cork material.  It came off one of the IKEA wardrobe that we had to dispose off to a newly married brother in law.  We had two of the enclosures.  We scavenged parts from one to repair the other.  We end up with some nice boards and material that contributes to my material storage (or junk if you are a housewife).  I could not use the cork board on its own as it was flimsy.  It does not have enough rigidity to achieve what I wanted.  So I had this pieces cut from a single board and pasted them together with contact glue.  But I had to make a jig to force the pieces to form an arch while the glue is drying.  Contact glue is insufficient to hold the shape for very long.  I would need to cover it with resin to force it to retain its shape AND make it waterproof.  This is cork that we are talking about.  Compressed Cork board that will easily expand when water creeps in and dry off.

 

Bracers

Side Bracers

For want of the real engineering name I would call them just Bracers.  This are intended for the mounting of the Deflector and holding them to the bases below.  Notice how the pieces are identical.  Manual filing is required to keep the shape that I wanted.  At this point in time, a general shape as close as possible to the intended final product requires wood working techniques that I have stopped using since my teens.

Base

Bases

This third part shall be the base where the bracers shall be attached. The base shall be mounted on the hatch of the car using 6mm bolts.  I have yet to source for a suitable retaining nut that is suitable.

 

I find woodworking as very satisfying.   It is a forgiving material.  My late father had woodworking as a hobby that consumed him after his retirement from the Government.   It just occurred to me that it is a dying skill here in Malaysia if not already extinct.  But it gives me the flexibility to make a prototype.  I do not foresee using wood or cork making its way as part of the final product but I must say it is an option I would like to keep.  You do not even need special training to work with wood.  Therefore I just lowered the ease of getting manpower to do it.  I may however use it as a composite material.  But I need to answer myself; Why?

 

Adjustable Spoilers Part 5

A day after posting Part 4.  I did a calculation using a spreadsheet.  I could either stick to my existing HITEC or get a slightly bigger one.  There’s a local Arduino reseller that has lots of TowerPro MG945 which has a stall torque rating of 12kg/cm at 6VDC.  I am definitely going to buy this.  Although the gears are of metal, due to the power that’s required, I prefer Nylon to take in the additional service demand.   I would also need to reduce the surface area by 30% while limiting the angle to not more than 30º.  As preparation to accept this servo I had to install a 3 wire cable taken from a power cord extension.  The length is about 1.3m which is sufficiently long to have the new controller next to the mid console close to the handbrake.  I have routed this through holes that were meant for the rear water jet for the wiper and through one for the spoiler mounting.  It’s a bit harder than just that, as I had to remove two panels and I had to make sure the cable was not interfering with the rear seat belt mechanism.

Cable Routing for Servo

While at the same time, I found the bracket for the reverse sensor a bit too big for my liking.  I therefore made holes to shave off 20g.  It was not planned.  Since it was hard to remove these panels, I would not be seeing it for many years to come.

Reverse Sensor BracketA few more days and I finished my mechanical build of the spoiler and had it fitted on the car yesterday 27 May 2014.  I had a spin in it around Putrajaya, in the most decent of 80km/h speed.  It did not fell off even though all of the wooden part was held in place by nothing more than Dunlop Contact Adhesive and two screws.  I had another spin today at much more livelier speed around the same track and it is still there on the roof.  I might add more screws to keep it all sane.  I used normal green coloured Garden Wire to secure the angle of attack.  I do not want the angle to be too big that it would add drag and load onto the new assembly.

Rev1 Front 3/4 view

New Wing

Rev1 Rear 3/4 view

I am happy to report that on the first test, I recorded an 18% fuel consumption reduction.  Initially the average at 80km/h is 5.3l/100km.  Now it is 4.3l/100km.  Tell me again how much that hybrid costs!  This is amazing.  Previously I could only make 4.0l/100km on a flat straight road.  But with this spoiler. I could drive it normally without having to use hyper-milling techniques to get close to that.  It goes to show that it does make sense to make the air separation as late as possible.  The angle of the spoiler closely matches the angle of the hatch.  I cannot be too sure if I had also reduced the wake.

With that I have completed the mechanical build and managed to clean the wet kitchen area of my house clear from tools and debris.  This gives much joy to my wife.  The next steps will be to finalize the electronics.

 

Adjustable Spoilers Part 3

I have purchased an Original Copy of an R3 rear spoiler for the Satria Neo to work on as a working development platform.  It is made out of Glass Fibre.  I normally would not do this if not for the fact that I was the told that the real deal would take some time to be ready.  I had gone to the Proton Parts Centre in Glenmarie, Shah Alam, Selangor to buy some parts for my other car.  I had asked for two sets but was told that it is not normally held in stock.  I was told that these parts do need to be back ordered.

Since what I am trying to do is make a full scale mock up and as a real working unit for further tests and development, I guess it would be ok.  It costs RM 140.00 which I purchased from an accessory shop called Brother’s from their main office in Kelana Jaya, Selangor.  There are actually two models of similar looking spoilers.  The difference is on the mounting holes.  I bought the proper one and took two more days before doing something about it.

I transferred dimensions from the spoiler to the wooden prototype wing and vice versa.  The wooden wing was wider than the spoiler’s trailing edge.  I chose to cut by 40mm offset from the shoulder of the trailing edge.  The hardest part was trying to cut it exactly straight as the spoiler is curved on all axises.  I used another straight wooden piece to make it straight.  I used a wooden saw, a dremel and a powered jigsaw.  And it came out shitty.  In retrospect, I should have just used the jigsaw.  I just had to be steady with it as an oscillating power tool is difficult to hold steady.

Severed Wing

Severed Wing

 

Once the trailing edge was cut, I tried placing the Standard Hitec Servo Motor around the cavity to see if there was room.  This has been the main question in my mind for weeks.  If the servo was too big, additional modifications are needed which would drag my schedule longer.

Servo Fits!

Placing the servo for fit testing

You can see from that picture that the Glass Fibre wing was made in several separate pieces.  Where they mate and glued to each other, there is some internal projections that hampered the fitment.

While finding placement for the servo it dawned on me that it would be easier to use the glass fibre cutoff as the moveable wing.  All it need would be to fit wooden pieces at either end.  These wooden pieces would then act as a swivel point on one end and a driven end at the other.  The driven end would only be a place for me to install a Servo Arm.  Then it occurred to me to measure the weights of the wooden wing and cutoff to compare.

Weight of Fibre Wing stands at 650g

Weight of Fibre Wing stands at 650g

Wooden Wing

Wooden Wing weight is at 442g

This appeared to me as simply amazing find.  While it is well understood that Glass Fibre is light and commonly used as lightening body shells, in this case; wood would be the ideal material.  Wood has very good compression properties.  In a spoiler, there would be some downforce on the top surface and wood would be excellent in this aspect of design.  It is strong while remaining light.  The negative side of it is its long term condition when exposed to wet, hot and humid weather of the tropics.  A nice light coat of shellac or even Plastidip could help reduce that.

While I had the wife’s baking scale out, I weighed the remaining part of the glass fibre wing. It weighed in 1073g.  In total the whole glass fibre wing would then be in excess of 1.7kg.  If we replaced that with wood, we could see a weight savings of more than 20%.

1073g

1073g

This could lead to replacing most of the structure into wood.  Saves fuel consumption by making a cleaner aerodynamic profile while saving weight!  Looks like I am onto something good here.