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ASLAV (LAV-25) 8X8 Military Vehicle

Discussion in 'Road Giants 6x6/8x8/10x10' started by ScaleBuilder, Dec 19, 2014.

  1. ScaleBuilder

    ScaleBuilder Well-Known Member

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    Hi guys and welcome to Project: ASLAV

    ABOUT THE PROJECT

    ASLAV stands for Australian Light Armoured Vehicle. It is the Australian variant of the LAV-25. Here is the 1:1 scale:
    [​IMG]

    This is going to be a build log of a 1/10 scale ASLAV 8x8 Crawler using a scratch-built chassis, and parts from multiple vehicles. It won't look exactly like a scaled down version as I have some additions of my own to add to it.
    I first discovered the LAV-25 while playing Battlefield 3 (video game) and it became my favorite vehicle mainly because how unique it looked (it's not a truck, nor a tank), the 8 wheels, the 4 wheel steering and it being amphibious in non-surf water. So I thought why not make an RC out of it. However I will be making the ASLAV variant. (Because I'm Australian haha)
    The purpose is to make an all terrain water proof vehicle that can traverse on-road, off-road, mild to moderate rock crawling, and through water. It will also have the ability to recover other vehicles through the use if winches (and maybe a crane arm). It is planned on being amphibious eventually.
    For more information about this vehicle see here: ASLAV - The Australian Light Armoured Vehicle Programme by Paul D. Handel

    The next post will be about the planning process.
     
  2. ScaleBuilder

    ScaleBuilder Well-Known Member

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    PLANNING

    The planning is absolutely critical for this build. Without a plan, I would not even attempt it. Good thing I am a drafter by profession (CAD), so my job is to make things fit virtually, so that everything will fit in reality.

    Now, when planning I couldn't figure out how I was going to make the 8 wheels so close together because from what I've seen on other people's builds is that they have a real tough time with drive shafts popping out or needing to be ridiculously short as well as being on crazy angles. Then there's the matter of mounting the transmission, transfer box etc. Too much work I thought. The answer?...

    Motor on Axles.
    Specifically the Bully 2 Competition Axles (thanks to DJmedic for his recent "Project Ultimate Overkill videos")
    These axles used mainly on competition crawlers have the motor mounted directly onto the axle. Well to the transmission actually, but that transmission is also mounted directly onto the axle.
    So what benefits do these MOA's provide?
    1. No drive shafts means none of those problems mentioned above.
    2. Transmission is already included on the axle.
    3. Don't need transfer cases
    4. Don't need to make motor mounts.
    5. Don't need to make servo mounts.
    6. Steering links can be bought specifically for the axles.
    7. Pinion gear included.
    8. Axles included
    9. Hubs and hub carriers included
    10. Upper link mount, lower link mounts and shock mounts are on the MOA.
    And because it's a solid axle, it should be good for crawling, and I don't need to worry about camber links, lower arms, etc.

    So I drew up models using dimensions provided from either RC4WD or the manufacturers website for the multiple parts that make up this build. This is so I don't need to actually buy the parts to figure out if they all fit together.
    The program I use is Autodesk Inventor 2013 for the solid modelling and dimensional drawings.
    I came up with a design, then figured it wouldn't work, then scrapped it. Then another design, and another, improving it each time. I was finally happy with the 6th version as you can see below:

    Note that colours are not final.
    First is the rolling chassis without the body panels. The orange things at the front are the batteries. (More information on electronics later).
    [​IMG]
    [​IMG]
    Rear quarter view. Rear body panel is not yet finalized.
    [​IMG]
    Gotta have that stance picture lol
    [​IMG]

    Then I simply place that model onto a dimensional drawing and get the dimensions out of it (well there's more to it than that).
    First drawing shows steering angle, dimensions between shock towers etc.
    [​IMG]
    And without the wheels attached for a better view.
    [​IMG]

    Overall length with body shell is approx. 680mm. Width approx. 260mm.
    As you can see, the chassis and the drivetrain are symetrical. This makes things simple. The axles are mounted in reverse front to rear.
    The gap between axles 1 and 2, 3 and 4 are small. There is a larger gap between axles 2 and 3.

    The chassis will be made out of:
    20mm x 12mm x 1.4mm aluminium unequal angle.
    25mm x 20mm x 1.6mm aluminium unequal angle.

    The aluminium will be held together using m3 hex stainless steel screws of varying length. Stainless steel so they don't rust. Hex is better than Phillips as it does not strip as easily if you have good quality hex drivers.

    The center of gravity will be mostly towards the front for better crawling capabilities. The COG will be low thanks to the motor and servo's mounted down low on the steel solid axles.
    The total weight will be approximately 5.9kg at first.

    The body will be made out of folded sheet metal. Most likely 0.5mm thick aluminium. (It feels stronger in hand then you might think, not tin can stuff). The aluminum sheets will be mounted around a roll cage. The roll cage will be made from acrylic rods (plastic rods). And glued together into a shape of a roll cage using epoxy. I could braze a steel roll cage using oxy-acetylene, but I don't have that in my shed. The purpose of the plastic roll cage is to not protect from jumping 2 meters in the air then landing on it's roof...I have a Traxxas slash for that. But it is there for rigidity of the body panels, and ease of use for when adding and removing the body shell for access to the electronics. More on the body shell much later.
    UPDATE: No longer making plastic roll cage, instead a metal brace.

    The upper links in the drawings mention 50mm in length. However, I will be changing them to 40mm to get the MOA's mounted at an acceptable angle.
    Lower links are 30mm length, very short.

    Wheels are 1.9inch and the tires will be 103mm in overall diameter. Any larger and they will rub while steering.
    Because the wheels are only 1.9inch, the rim or tires might rub against the Bully 2 Comp axle hubs. So I will be offsetting each wheel using a 15mm wheel hex extension. So the track width will be 30mm wider overall.

    Then there is the matter of the electronics. UPDATE: Voltages updated, thanks drzoo2
    [​IMG]
    The ASLAV will be running off two 3s batteries. One battery for powering each of the two ESC's. Each ESC will power two brushed 35Turn motors.
    UPDATE: Will only need 1x 2s 7.4V Lipo Battery for everything.
    The servo's will be connected via a Y splitter.

    8 wheel drive , 4 wheel steering, 4 motors, 2s lipo power...hella yes

    Next post is parts arrival.
     
    #2 ScaleBuilder, Dec 19, 2014
    Last edited: Nov 28, 2017
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  3. drzoo2

    drzoo2 Studio Forums Elite
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    One note on your voltage for each motor. You have them wired in parallel so each motor will see 11.1v, not 5.55v. I'm mentioning it because you have listed a 7.4v max for each motor.

    Very awesome work...I'm guessing you do CAD for a living?
     
    #3 drzoo2, Dec 19, 2014
    Last edited: Dec 19, 2014
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  4. ScaleBuilder

    ScaleBuilder Well-Known Member

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    Yes, correct, I forgot to change that!
    yeah I do drafting/CAD for a living.
    thanks for posting.
     
  5. drzoo2

    drzoo2 Studio Forums Elite
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    No problem. Your work is defiantly that of a professional. Very clean. Solid Works?

    Are you changing the cell count on your main batteries to 2S to meet the motor voltage spec? I wouldn't change the parallel configuration to series.
    By rewiring what you have to making it series, meeting your 5.55v specification, you'll also significantly lower the power each motor is capable of using.

    Given your motor specs listed, 7.4v @ 5amps. Each motor has an effective DC resistance of 1.48ohms.....

    Put in series, you double the total resistance in the circuit to 2.96ohms while also halving the voltage as you have spec'd to 5.55v
    5.55v / 2.96ohms = 3.75amp draw each motor.
    5.55v * 3.75amps = 21 watts per motor.


    Leaving it parallel but dropping to 2S
    7.4 * 5amps = 37 watts per motor

    Unless of coarse your way ahead of me and you really want the lower power........
     
    #5 drzoo2, Dec 20, 2014
    Last edited: Dec 20, 2014
  6. HellRide

    HellRide New Member

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    dude that's pretty freaking awesome!
     
  7. ScaleBuilder

    ScaleBuilder Well-Known Member

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    Program is Autodesk Inventor 2013

    Yeah that's it.
    I was initially going for series but then changed the wiring to parallel. But forgot to change the numbers.
    so the motor max input should be 11.1v each so they handle 3s each.
    However, today I tested with just one 2s on 2 motors and it provided adequate power. So looks like I might go 4s instead of 6s.
    what do you think about wiring all 4 motors to just one ESC? (Parallel).
    I thought it was too risky but there is little amp draw from the 4 motors anyways.
     
    #7 ScaleBuilder, Dec 20, 2014
    Last edited: Dec 21, 2014
  8. ScaleBuilder

    ScaleBuilder Well-Known Member

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    Thanks man!
     
  9. drzoo2

    drzoo2 Studio Forums Elite
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    60amps seems adequate considering you listed the motors @5amps per but what you have to consider is the ESC source impedance and the load it was designed to handle. It's rated @ 60amps but if the load resistance begins to approach that of the source impedance of the ESC, you start dropping power at the ESC instead of the load (motor). I think this is why manufactures also rate their ESC's in motors turns. The total of 4 parallel 35turn motors should be roughly similar to a single 8.5turn.

    What is the motor limit for your ESC on 2S?
    And for 3S?
     
  10. ScaleBuilder

    ScaleBuilder Well-Known Member

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    Hmmm...impedance and resistance is beyond me! I'm no electrician...

    Anyways the ESC is a Hobbywing 1060 WP 60A brushed. According to the manufacturer's website, it can handle 1 or 2 motors. It did not mention anything about 3 or 4 motors etc.
    Also what was interesting that may relate to what your saying is that Hobbywing recommends increasing the turns of the motor when running with 2 instead of 1 motors.
    If running with 4 motors is roughly equivalent to a 8.5T motor, then this ESC is probably not suitable. It is only rated for 12T or more motors on 2s or 3s.
     
    #10 ScaleBuilder, Dec 21, 2014
    Last edited: Dec 21, 2014
  11. ScaleBuilder

    ScaleBuilder Well-Known Member

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    PARTS ARRIVAL

    First is some pictures. Sorry, I lost some of the other pictures, but this is most of what I ordered so far.
    I ordered half of the parts at first so I can test it and see how it works. Then I will order the rest of the parts.
    Note that a lot of parts will be painted later.
    [​IMG]
    Some more necessary stuff.
    [​IMG]
    Yeah racing shocks 70mm uncompressed hole to hole. Using the included soft springs. Team associated 30WT oil. UPDATE: These were temporary
    [​IMG]
    Wheels assembled already. Gmade sr-03 beadlocks with RC4WD Trail Buster tires. (I have since mounted the wheel nuts on the outside as it looks more "military").
    [​IMG]

    Here is a list of parts I have ordered:
    • Bully 2 Competition MOA's (front) x4
    • Bully 2 Competition steering links x4
    • Hobbywing 1060 WP 60A ESC Brushed x2
    • Savox waterproof servo x2
    • RC4WD 35T crawler motor brushed x4
    • Gmade SR-03 1.9 beadlock uncoated steel wheels x8
    • RC4WD Trail Buster 1.9 tires x10
    • 7.4V lipo x2
    • RC4WD 12mm wheel hex 15mm extenders x8
    • Yeah Racing 70mm shocks x8
    • Ball ends x20
    • Ball ends bent x20
    • Links aluminium 30mm x8
    • Links aluminium 40mm or 50mm x8
    • Set screws m3
    • Bunch of 14awg or 16awg cables
    • Bunch of m3 button head stainless steel nuts and bolts
    • Hook and loop tape for battery mounting (AKA Velcro)
    • Y-splitter cable for servos x2
    • A scale sleeping bag just because

    Next update: Assembling MOA's with links, shocks, wheels, etc.
     
    #11 ScaleBuilder, Dec 21, 2014
    Last edited: Nov 29, 2017
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  12. drzoo2

    drzoo2 Studio Forums Elite
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    Looking forward to your progression on this......
     
  13. BlackPhoenix

    BlackPhoenix Studio Forums Elite
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    This is looking pretty awesome so far. Earlier this year I was building an Australian Army Recovery Truck. It was based off the Mack MC3 which is one of the recovery vehicles they use (what I plan to drive when I join). Unfortunately I ended up not finishing the build as I was encountering too many problems and I wasn't able to get it all to work they way I had planned. I would like to revisit one day but working with all of that styrene has given me nightmares. Hahaha :)
     
  14. ScaleBuilder

    ScaleBuilder Well-Known Member

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    Sounds interesting!
    I was worried styrene would not be strong enough so I am going with sheet metal.
     
  15. ScaleBuilder

    ScaleBuilder Well-Known Member

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    MOTOR ON AXLE ASSEMBLY

    Ok, now I start building!
    [​IMG]
    This is how the lower links are assembled.
    [​IMG]
    A bunch of parts that make up the MOA assembly. The servo is temporary, will replace with a better servo later.
    [​IMG]
    This is how the 15mm wheel hex extenders get mounted onto the existing 12mm wheel hex. Then the wheel, then the washer, then the special wheel nut that looks like a bolt.
    [​IMG]
    Close up shot of the 15mm wheel hex extenders (between steering hub and wheel). They keep the tires from rubbing on the steering link ball end while steering. Gives it a nice wider stance too.
    UPDATE: Cant find original photo :(
    Here is the Bully 2 Competition MOA's assembled with motor, servo (temporary Traxxas servo), pinion gear, shocks, steering links, servo arm, upper and lower links.
    [​IMG]
    Close up shot of how the lower link and shock are mounted to the axle.
    [​IMG]

    (continued below)
     
    #15 ScaleBuilder, Dec 23, 2014
    Last edited: Nov 29, 2017
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  16. ScaleBuilder

    ScaleBuilder Well-Known Member

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    MOTOR ON AXLE ASSEMBLY

    And another picture showing how it looks directly from the front.
    [​IMG]

    If you look in the CVD's they don't have grease, so I will need to grease them. (noob question alert) Should I use my Tamiya grease stuff? It is for CVD's just want to make sure.
    Also, the gears are already coated with a light grease. Do I need to grease them up more, or is it done out of the box already? Thanks.
    I will be doing the greasing just before I run it, so that grease doesn't go everywhere as I'm working on it.

    I most likely won't be posting until boxing day, too busy cooking lobsters and ham!
    Next update is chassis.

    And Merry Christmas! :haveaniceday:
     
    #16 ScaleBuilder, Dec 23, 2014
    Last edited: Nov 29, 2017
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  17. ScaleBuilder

    ScaleBuilder Well-Known Member

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    CHASSIS

    aaaand...I'm back.

    Here is some of the chassis so far.
    [​IMG]
    I used a template for when I'm drilling holes. I move the same template across the chassis rails so that every hole spacing is exactly the same. I couldn't do this without a template.
    Sometimes I had to use three clamps, as I don't have a bench vice (or even a work bench lol).
    [​IMG]
    600mm length with holes drilled.
    [​IMG]
    Here is the template clamped onto the work piece while being drilled.
    [​IMG]

    I am now awaiting the rest of my parts to arrive. (After Christmas sale specials yay).

    next update will be the completed chassis.
     
    #17 ScaleBuilder, Dec 27, 2014
    Last edited: Nov 29, 2017
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  18. drzoo2

    drzoo2 Studio Forums Elite
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    I like using a dry lube so dirt doesn't build up in the grease. Graphite is great stuff but a real pain to use. It's messy and hard to get it to bond to the surface your trying to put it on.
     
    ScaleBuilder likes this.
  19. ScaleBuilder

    ScaleBuilder Well-Known Member

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    Thanks drzoo2, I will look into it.
     
    #19 ScaleBuilder, Dec 30, 2014
    Last edited: Dec 30, 2014
  20. ScaleBuilder

    ScaleBuilder Well-Known Member

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    CHASSIS

    An update on the chassis. I got it mostly assembled. Still need to do the cross members for more rigidity.
    [​IMG]
    I used a heat gun and the flat nozzle attachment to scrape off the annoying bar code sticker.
    [​IMG]
    8mm m3 bolts are just the right length with the m3 nyloc nuts.
    [​IMG]
    And here it is so far.
    [​IMG]
    Still have to wait a little while for the rest of the parts to arrive.

    Next update is either more chassis work or all 8 wheels assembled to the chassis.
     
    #20 ScaleBuilder, Dec 30, 2014
    Last edited: Nov 29, 2017

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