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Old 02-15-2013, 09:35 AM   #16
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Default The second revision.

And I hope this will be the last one

After two days of intense testing with the actual car I can say with confidence that the 4WS is at least as fast as any other TC out there. For me it offers the option to gain more steering and/or a better balance just by doing little changes with the rear steering. Now that the car nearly reached the maturity phase I used all collected information to redesign every prototype part of the car.

This is the result:



Now the details. Like I mentioned before I forgot the camberlink holes on the shocktower. So I added them and did a complete redesign to both towers. The rear tower lost the outer two holes for the shock because I never used them or saw a team driver use them. This has the effect that the shocktower can be a little more narrow to be out of the way of the rear camberlink when the shock is fully compressed. With the lowered shocktower the car is 8mm lower (TC6=64,5mm; 4WS=56,5mm).

Front shocktower:


Rear shocktower:


from behind:



Lets take a look at the servo and its surrounding:


Servos always have these big holes (5mm diameter) instead the 3mm I would need for the screws. To prevent any movement I designed an insert to fit the holes in the servo. It has two threads and allows to mount the servo to the spurgearbulkhead without having the spurgearbulkhead bend like it could happen on my previousdesign:






The spurgearbulkheads got a new design because of the new servo mounting, a lowered servo (it now sits on the chassis) and a little finetuning with the belttension.

Spurgearbulkhead, right:


Spurgearbulkhead, left:



I also changed the LiPo-brace for two (or more) reasons:
1. a rear brace can also be used to secure the servo, protect it in impacts and limit the servomovement under load to zero
2. the shorty is now hold in place by three elements and is secured better.






The chassis itself changed not, but the positions of the drill holes changed a lot:



New are two maintenance holes below the right spurgearbulkhead to be able to unscrew or check the screws that secure the servo.




Now I hope I didn't make an error. If you guys see something strange please tell me. I will look at it some more and then order some cfk.

I think with these ideas the car will be bulletproof and offer the full variety of setup possibilities. In about 3-4 weeks the car will have the new parts. Then I will again focus on setup and later prove its abilities in a race.

Edit: What I am wondering right now. If it would be possible to use a one-way or spool in the rear?
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Old 02-15-2013, 09:50 AM   #17
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To me it would seam u wouldn't want as much steering in the rear as in the front . Also why couldn't u keep servo in same position as stock and just run a longer link to rear this would keep ur links close to center line and low with more efficient angles , giving more Lineior steering. Love the concept and approach very nice attention to detail . How about u make some more servo spaces bushings . I'll buy 5 pair . U have a product that u can sell 10000 of there alone !!!
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Old 02-15-2013, 10:11 AM   #18
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This is the best homebrew project I've ever seen on RCTech. AE should hire you. Good luck, I'm quite interested in your results.
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Old 02-15-2013, 10:22 AM   #19
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Originally Posted by jlfx car audio View Post
To me it would seam u wouldn't want as much steering in the rear as in the front . Also why couldn't u keep servo in same position as stock and just run a longer link to rear this would keep ur links close to center line and low with more efficient angles , giving more Lenoir steering. Love the concept and approach
The reason for the location change of the servo is:
1. weight balance
2. the position had to be changed anyway
3. without position change one turnbuckle would have to go below the topdeck between battery and spurgearbulkhead => collision
4. the turnbuckle angle does not have an inconsistent effect on the steering angle right now. Except you want the tires to turn into the same direction you actually can not reduce the angle of the front turnbuckle with the actual servo position.

This is what I found out in many days of trying with different servo positions. Maybe you saw something I missed. Can you visualize your idea? Thanks!


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How about u make some more servo spaces bushings . I'll buy 5 pair . U have a product that u can sell 10000 of there alone !!!
Really? I check out the prize and tell you. Then you can decide if you want them. Or I mail the CAD-drawing and you let them mill on your own...
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Old 02-15-2013, 10:29 AM   #20
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I can see it in my head but doing the PC work is the part I'm ignorant about including spelling as u can see...
I mean could u not lay servo down with horn on inside and both rods connected to same side of horn ( tho I think this might be the problem being front and rear have to turn opposite directions...) just looking at ur tirod angles when u to the right it seems as it wouldn't be linear (more progressive) than to the left
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Old 02-15-2013, 10:36 AM   #21
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I can see it in my head but doing the PC work is the part I'm ignorant about including spelling as u can see...
You know it's bad when someone from Germany writes better English than you.
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Old 02-15-2013, 10:44 AM   #22
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I can see it in my head but doing the PC work is the part I'm ignorant about including spelling as u can see...
I mean could u not lay servo down with horn on inside and both rods connected to same side of horn ( tho I think this might be the problem being front and rear have to turn opposite directions...) just looking at ur tirod angles when u to the right it seems as it wouldn't be linear (more progressive) than to the left
OK, I think I know what you mean. I think I tried this idea. But I did the collision test with the old spurgearbulkheads and it didn't work for the full servoarmangle. There was also a collision with the battery. Another thing is that I had to push the battery forward to an unhealthy amount. But you are right with the servo that way the angles are nice. Unfortunately I would need a low 1S battery to make this idea work. It is always a compromise. Nevertheless, thank you for this thought
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Old 02-15-2013, 11:42 AM   #23
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Einfach nur geil! Muss nen irrer Aufwand gewesen sein, alle Teile ins CAD zu bekommen, ne?

Gruß,

Christian
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Old 02-15-2013, 12:03 PM   #24
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You know it's bad when someone from Germany writes better English than you.
Yea tell me about it ... I spell so bad my super smart phone can correct all my bad spellings and if I do manage to get it right , my phone will auto sign it (to fit my normal spelling ) its that smart of a phone .
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Old 02-15-2013, 12:48 PM   #25
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Einfach nur geil! Muss nen irrer Aufwand gewesen sein, alle Teile ins CAD zu bekommen, ne?

Gruß,

Christian
Danke für die Blumen

Es hat mich ca. eine Woche gekostet den gesamten TC6 in CAD nachzubauen. Ich weiß garnicht mehr was mich damals geritten hatte Heute hätte ich keine Lust mehr darauf!
Der Rest (also der 4WS und andere Varianten) war im Prinzip nicht mehr so aufwändig. Nur die Servopositionierung kostete richtig Zeit. Die Teilegeometrie selber ist relativ simpel.
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Old 02-15-2013, 07:51 PM   #26
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With your current design, do you feel like the car is twitchy? Do you still feel like it has too much steering? Is it something that takes a while to get used to?
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Old 02-15-2013, 08:44 PM   #27
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This is totally cool !!

After looking through the entire ROAR rules, I couldn't find anything in regards to 4 wheel steering. If this was allowed, it might only be done in the modified class.

Question, Did you ever think of just adding a second servo behind the battery, and wire it with the one up front ?
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Old 02-16-2013, 02:55 AM   #28
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With your current design, do you feel like the car is twitchy? Do you still feel like it has too much steering? Is it something that takes a while to get used to?
After the above mentioned setupchanges the car was very easy to drive. One thing you have to get used to is the on power steering. You can release the steering much earlier than with a normal TC. I got used to it after the second test day.



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Question, Did you ever think of just adding a second servo behind the battery, and wire it with the one up front ?
No, I didn't. What advantages will I have from the use of two servos that will react in the same way?
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Old 02-16-2013, 03:26 AM   #29
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This is the best homebrew project I've ever seen on RCTech. AE should hire you. Good luck, I'm quite interested in your results.
+1
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Old 02-16-2013, 03:31 AM   #30
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This is totally cool !!

After looking through the entire ROAR rules, I couldn't find anything in regards to 4 wheel steering. If this was allowed, it might only be done in the modified class.

Question, Did you ever think of just adding a second servo behind the battery, and wire it with the one up front ?
I actually built a hpi pro 2 that way ten years ago with a second servo in the rear and used an airtronix splicer cable ,had both servos hooked up to steering port of the receiver and I messed around with it but had inconsistent results.This project has been much more thought out and developed out of pure engineering brilliance. It is something to be admired.
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