+ Reply to Thread
Page 1 of 4 1 2 3 ... LastLast
Results 1 to 10 of 34

Thread: CURT16 Building Process

  1. #1

    CURT16 Building Process

    This year i would like to post the building process of our second car in Cairo Uni FSAE team. i want to go forward to the core of the topic without typing too much as an intro, but what i would like to say that: i'am sure that in this topic our team will gain many things.

    This year we modify 2015 car with the main goals of:
    - Building a car complies with the rules(seems stupid, every team should do so) but unfortunately we didn't join the dynamic events last competition .
    - Finishing the car 4 month prior to the competition date (This year we are planing to join UK competition)
    - We don't have high goals regarding the dynamic events. joining the dynamic event with the main goal to finish the endurance is perfect for the team. But we do have some goals on the static events.

    Moving to every single system (Our goals regarding this system, and what we have finished so far).

    The power train:
    - Engine: in 2015 we have used KTM 450 EXC engine we do not have any plan to change it this year.
    - The intake system: this year some modification regarding to the material of the intake system and its integration on the car.
    - The exhaust system: Some modifications related to it's packing in the car.
    - The radiator: we will design another radiator with the main goal to finish the endurance.
    - The fuel system: we are still using the motorbike pump and we will modify the fuel tank.
    - For the differential and for financial reasons we will use Torsen differential, with some modification on its fixation.

    The suspension
    - Last year we have spent a lot of time on the suspension kinematics. but we ended with a complex suspension with some errors in the manufacturing and many deviations from the designed points. although we are working to increase the team understanding level of the suspension. but with the main target to finish the car very early we will do it simple, no time to spend to optimize the dynamics, no anti features , direct acting . . . if i want to set the suspension goals this year:
    1 - A simple suspension (Less time in designing and manufacturing)
    2 - well mechanical designed wheel assembly.

    - Although Mr Pat has advised us to use 13" wheels, but we do have 2 sets of tires + rims that are ready to be used. so this year we will go for 10" wheels.

    The brakes
    - We went very fine in braking system last year (we have some braking testing) this year we are planing to go for angled M/C pedal box (Decision matrix).
    - last yea we faced some problems in the brakes lines as we used local lines but this year we are planing to buy them from an international supplier.

    The chassis.
    - Unfortunately the main reason for not joining the dynamic events in FSG15 was the chassis , so we will focus more on the chassis rules.
    - Simple and minimum required tubes chassis is considered enough (Removing extra tubes, planar tubes, easy to be jigged during the welding process)
    - In Egypt we don't have the minimum required tubes stated in FSAE rules we have thicker and larger tubes. this year we want to deal with an international supplier to supply for our chassis tube (It's not a final decision) but this will reduce the chassis weight 20 kGs (As if you designed based on the minimum available tubes size in Egypt you will be lucky to end with a 50Kgs chassis).

    - The electric team
    we have switched from using the stock KTM ECU to megasquirt, so the team is now working with the engine team to run the engine .
    we want to do the minimum requirements from the competition regarding the electric system although we have received some negative feedbacks from the design judges in FSG15 as we have to use more sensors. but i think this year a running car 4 month before the competition is our main priority.

    In the next comments i will add what we have finished in the car CAD model.
    Last edited by Ahmad Rezq; 09-11-2015 at 11:09 AM.

  2. #2

    The Chassis Design.

    Some Photos from the Chassis Design.

    1.JPG2.JPG3.JPG4.JPG5.JPG

  3. #3
    We are planing to machine the suspension brackets and bolt them to square tubes in the chassis. But we are still analyzing the decision.
    Also as shown in the picture we will machine our rod end spacers.
    Attached Images

  4. #4
    Here's a suggestion if you want to decrease complexity and eliminate a major mechanical design fault: no rod ends in A-arms. Unless you have 5 independent link suspension there's no way to use them to make adjustments without introducing bending stress into the parts. Plus, it's lighter!

    Other list of suggestions:
    - why use bolted suspension brackets? waste of time, just waterjet some steel tabs and weld them on
    - why is the driver so far away from the engine? subtract that ~6" of chassis and save even more money and weight
    - your engine mount points are complete untriangulated
    - why is the front of the chassis so damn large? I see this a lot in developing teams, never can understand why the front bulkhead is so high. Just make the frontmost bulkhead the same size as the standard IA, no larger.
    - are you really using .5" od tubing for suspension arms? What wall thickness? rear a-arms look buckling prone to me, what is target car weight?
    - rear toe base is hilariously small, can you say "terminal toe compliance"
    - In addition the rear toe link is putting serious bending loads into the a-arm tube that it's mounted too. This could work in the sense that it won't break, but again looks like you're using very small OD tubing...
    - I seriously doubt you need that much space behind the chassis for the differential, just move the entire sprung assembly backwards relative to the wheels
    - rear bulkhead is untriangulated, use some of your .5" OD tubing to stiffen it up maybe. Or get rid of the 3-part upper member with 45-degree welded joints? seems to serve no purpose
    - side-view triangulation is pretty complete, top view not so much (thank you SES for only caring about side view)
    Penn Electric Racing

  5. #5
    Hello Adm, Thank you for your notes. I got your all points.

    - I'am about reduce the rear zone to save some weight (so completely agree with that point).
    - For the front zone height: I'am sure you went trough this process ( The Percy rule + the templates + steering column + steering wheel) all together defines the front zone.
    - 15 mm the outer diameter (yes in the shown pictures they are smaller but things they are updated now) of the suspension links (In Egypt market we have narrow options).
    - I'am planing to increase the toe base in the rear suspension (Totally agree with you).
    - (Edit) Target weight 180 kgs with +20 kgs acceptance (some lap simulations were done on optimum lap).
    - some members are added to the floors.
    Last edited by Ahmad Rezq; 09-11-2015 at 04:03 PM.

  6. #6
    Some short comments:
    I agree that rear-toe compliance would be bad. Increase the toe-base on the rear upright, and rethink the wishbone angles.

    Your firewall will need to come further forward, inline with your seat back. As for normal packaging, your fuel tank and battery and exhaust pipe would all be forward of the engine, but behind the firewall.

    Looking at your Percy template, it seams the driver sits very upright. That's fine if that's what you want, it creates good visibility, and possibly low yaw for turning. For our car I have chosen a much more reclined seat angle, of about 40 degrees to horizontal. This is for lower center-of-gravity, with a small trade-off in visibility.
    University of Tasmania (UTAS)

  7. #7
    Senior Member
    Join Date
    Mar 2005
    Location
    Australia
    Posts
    1,690
    Ahmad,

    Very good that you are doing this build-log. There are many, many benefits for your Team. I know you know this, because you have seen the results on Jonny's and Christian's (Aston Uni) similar threads.

    Most important at this early stage is that you keep all your thinking very fluid.

    DO NOT LOCK-IN ANY DETAILS OF THE DESIGN!

    So, do not put too much "value" on your current frame designs. Best to print out your above design, then DELETE the file on computer. Then do another dozen+++ similar quick-and-dirty layouts. Print on paper, and delete on computer. Or, better yet, just hand-sketch on paper.

    Then, after a week or two of all the different frame designs swirling around in your head, get the Team together to have a critical review session of all those different ideas, as they appear "roughly sketched on paper".

    Perhaps someone will suggest that Design-1 (ie. the one above) "...seems to have an unnecessarily large ground clearance of about 120 mm, which, err..., raises the whole car's CG too high?!!!". And other such useful comments (such as Adam's and Jonny's above).

    So you can tear-up that first sketch, and focus on the many other rough layouts you have...

    Repeat: Keep everything flexible now, so you can gradually home-in on a reasonably good design.

    Z
    Last edited by Z; 09-12-2015 at 05:15 AM. Reason: grammar!

  8. #8
    Ahmad,

    What is the reason for selecting that longitudinal position for the rear bulkhead?
    How much clearance do you think the driveshafts need to the chassis?
    How much angle can you run on your tripod joints?

    Please completely revise your rear toe control... even if it adds many kg. Rear toe compliance will destroy your chances of driving fast, a few extra kg will not.
    UQ Racing

  9. #9
    For the rear toe compliance issue, I think the most normal thing to do would be to move the lower upright mounting point forward. The rear upright mounting points don't need to be inline with the axle, so spread the 2 lower points out either side of the axle.
    University of Tasmania (UTAS)

  10. #10

    2nd trial

    Jonny Rochester
    Thank you for your notes. For the firewall a lot of modification after completing the car assembly with the engine parts.
    For the toe control I moved the rear control arm mount on the upright 30 mm to the right and the tie rod 30 mm to the left. Now the normal distance between the tie rod and the line connects the 2 control arms mounting point is 51 mm now.

    Z
    I do agree with you Erik in doing dozen of designs and modification as long as the team will follow the time of the design phase. and in this post 2nd trial with some modifications is attached.

    Mitchell

    What is the reason for selecting that longitudinal position for the rear bulkhead?
    How much clearance do you think the driveshafts need to the chassis?
    How much angle can you run on your tripod joints?
    - Actually the rear area was built with the main targets to ( 1- increase the engine area as we faced many troubles during the assembly of 2015 car , 2- No rear box design. 3 - supporting the control arms on the rear area corners) some Cms were added to the 2015 chassis design and i do agree it's very large)

    - In the shafts clearance : IMO the clearance that neither the sprocket nor the shafts hit the chassis tubes during their operation.

    - We are using Tripods and shafts from RCV, if i do remember very well i think about 12 degrees
    ------------------------------------------------------------------------------------------------------------------
    In the 2nd trial
    - the rear zone was minimized ( some inches were added to the cockpit )
    - The side impact area were redesigned to reduce the driver height from the ground to lower the CG and the nearest member to the ground is around 4 cm
    - Regarding the toe control as I've mentioned earlier I moved the rear control arm mount on the upright 30 mm to the right and the tie rod 30 mm to the left. Now the normal distance between the tie rod and the line connects the 2 control arms mounting point is 51 mm.
    ((SOME TUBES WILL BE ADDED TO THE FLOOR))

    I'am working on reducing the height of the bulkhead and also reducing the engine CG height.
    Attached Images
    Last edited by Ahmad Rezq; 09-13-2015 at 04:43 PM.

+ Reply to Thread
Page 1 of 4 1 2 3 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts