The Definitive Guide to Anti-Squat on Scale RC Crawlers - Part I: The Theory (Textbook Version)
ฝัง
- เผยแพร่เมื่อ 2 มิ.ย. 2024
- This is the first Anti-Squat explanation specific to RC Rock Crawlers. Learn what works and what myths abound. Not all physics from full scale 1:1 vehicles translate to scale rigs! Get your tuning right with the knowledge in this video. This is the Part 1: THEORY.
00:00 Intro
00:39 The Myth
00:54 How Do You Drive?
01:49 Velocity Definition
02:06 Acceleration Definition
02:33 Real World Examples
03:34 The Balance Scale Analogy
04:30 Acceleration and Sprung Weight
05:50 Anti-Dive
06:07 Full Droop
06:24 Rear Torque
07:14 Other Factors
07:21 Front Overdrive
07:41 Ultra-Light Sprung Weight
08:02 Traction
08:24 Link Risers
09:20 Pro Tips that Work
10:02 Negative Springs
10:18 Larger Wheels
10:43 Real Life Geometry
10:47 Priorities
10:56 End
11:01 About the Author
11:22 Acknowledgements
#antisquat #antirise #antidive #linkriser #acceleration #velocity #rc #rccrawler #crawler #rccrawlers #rctruck #rccar #rccars #rc trucks #radiocontrol #rccrawling #rccrawl #newtonslawofmotion #newtonslaws #newtonslawsofmotion #kineticenergy #potentialenergy #inertia
About The Author
/ jason-chamberlain-9697...
Backhoe Dragster - 100mph JCB GT
• Backhoe Dragster - 100...
New vs Old Muscle cars drag racing
• New vs Old Muscle cars...
Tesla Plaid vs ZR1 Corvette Drag Race
• Tesla Plaid vs ZR1 Cor...
Enginerding: What Is Anti-Squat & How Does It Actually Affect Mountain Bike Performance?
www.pinkbike.com/news/definit...
Motorcycle Handling and Chassis Design by Tony Foale
motochassis.com/product/book-...
Losing Grip - Center of Gravity and Being Clever about Upgrades
www.bigsquidrc.com/losing-gri...
CRAWLPEDIA: 4-Link Suspension Guide - Anti-Squat, Anti-Dive, & Roll Center
www.crawlpedia.com/4_link_sus...
Correction: 10:36 Numbers are Backwards - เพลง
![[TH] VCT Masters Shanghai Playoffs DAY 3 // FNC vs FUT | EDG vs PRX](http://i.ytimg.com/vi/pw2T5v0ogDI/mqdefault.jpg)
I'm an engineer too, studying RC Crawler from 5 years always making experiments for better climbing performances.
I agree in most of your assertions except the one about rear tire size.
In my opinion, study and real life experiments... there is a phenomenon you have messed: bigger rear tire elevate the CG far from oblique ground, reducing the momentum of the CG weight respect to the fulcrum (that is the point the rear tire touch the ground).
Having enough torque and total grip, the matter is: how far is the GC from the ground ?
Bigger tires give more traction because of a wider footprint, but elevating the GC (if there is no other change to chassis) makes wheelie most probably.
Thanks for sharing !
That is a fair point. My assumptions was that you correct the chassis height when switching tire size. However, your point is valid in that the axle and tire height will always be higher than smaller wheels.
Finally someone who has the correct information when it comes to crawling! Very accurate and detailed. Pay attention people this spot on!💯🤜
Thank you!
a man of science...you speak my language sir. Thank you for the epic explanation and illustrations.
You are very welcome.
Extremely useful! Thank you!
First off i really like your video. Always looking to absorb info and knowledge. One thing im thinking about though is that when on an incline there is still acceleration affecting the crawler even if its not moving. Gravity 9.81m/s/s. F=ma. No accel no force. Just a thought. It may be a low acceleration but its still there and will increase with velocity upwards. This may make anti squat still a thing. Just my 2 cents.
I like your line of thinking. It's a little out there, no offense intended, but you are trying to understand and putting up some fair terms.
The gravitational constant is in the units of acceleration - true. In this case, gravity is pulling your mass downward, equalling a static force F on the chassis. This is the force causing your vehicle to push against the springs and your tires to compress. It's also the force that translates mass into a weight. Remember, mass is mass anywhere in the universe, but weight is relative to your gravity constant. It translates to a vertical static force acting on the vehicle. This is far different that the dynamic weight shift caused by horizontal motion.
Anti-Squat is a horizontal acceleration where the wheels move out from underneath the chassis, wanting to compress your rear shocks. Anti-squat linkage counteracts the force on the shock and keeps the chassis level.
The fact that a gravitational acceleration exists in the world has nothing to do with the acceleration anti-squat is reacting too. I hope that makes sense.
This was a great video! Really enjoyed watching it and appreciate your insight! Thank you
Glad you enjoyed it!
Thanks Jason, super informative video here. Going to make some mods to my cheater rig and see how I can improve.
Great explaine 👍
Thanks for sharing 👍 is it possible that you can upload a video regarding the various mounting points for the upper links on some chassis and how that might effect the performance?
Good idea. I can try to get to that. For now, if you move the rear upper link UP on the chassis, it increases Anti-Squat. Move it DOWN and it lowers your Anti-Squat. Remember this only matters when you are accelerating. If you are slow speed creeping - it doesn't matter. I would set them wherever it's most convenient for your build. I have mine UP for clearance to the lower links.
Great lesson 👍🏻😃
It's true! But regardless, I always use link risers because when are you ever at a constant velocity when climbing? You will come to a stop, and to get going again, you'll have to accelerate. However small, a link riser may reduce how much the front lifts by 3%. But that 3% may be exactly what I need to complete that climb. 👍
What do you think of a crawler with absolutely no suspension/real world suspensions movement for climbing?
For RC crawling, I feel like all you really need is articulation between the front and rear wheels. You could theoretically get rid of all the links, and simply have a single rotational pivot around the roll axis (using an airplane coordinate system) somewhere between the front and rear axles. Anti-squat, anti-dive, anti-roll 4-bar linkage arrangements are all carry over from full sized vehicles (which need those parameters BTW) whereas 1/10 scale doesn't need it for many reasons which I tried to highlight - sprung weight, overdrive, etc. I don't think most people could wrap their heads around that concept yet, and it wouldn't fit any rule classes, but I may build one someday soon.
Small details make a difference for sure. In the realm of anti-squat, the acceleration has to be great enough to at least overcome shock friction, and crawlers run very thick and slow oil. You may not even NEED AS to keep the chassis level because the shocks are doing it.
It still seems like magic to me!
Good stuff to know right here
When your crawler gets stopped or slowed by a low traction situation, such as climbing a rock, what do you do?
I'm not sure I understand the question. If your wheels are slipping, I slow down and try to regain traction. If your wheels are bound up you gotta go backwards to dislodge. It is possible to drive forward with spinning wheels, like a drift or rally car - in which case your linkage design is negated. You can also try popping the throttle and see if you can surge past the obstacle.
@@BoomslangSuss what does popping the throttle do?
If you hit the throttle, it’s just another technique in the quiver to try. Sometimes a quick impulse with momentum will help you clear an obstacle if a slow approach doesn’t work.
@@BoomslangSuss so you accelerate?
@@kel5944 Yes, that would be an acceleration event. Yes, anti-squat kicks in for that situation assuming you're inducing enough dynamic weight shift.
Thanks for sharing
My pleasure
Hell Yeah very informative
this is amazing. thank you. My issues is what happens if you go fast and slow, axial rr10 bomber two speed tranny and sensored brushless... Im struggling to find the happy medium
Aren't we all...😂
Is there a negative effect to raising the rear links? I have found link risers helpful to avoid binding issues and making space for bent or high clearance links.
Not really. If you need it for clearance, that is a great reason.
Anti squat has no effect on slow speed...correct but it certainly has on acceleration.... Crawler constantly accelerate.. So a rear axle riser make sense in some application 😉 BTW in one graphic the weight bias shown is the opposite of the picture.10:35
Oh snap! Good eye. Thanks for that.
But what if I want to put the lower link of the rear suspension parallel to the ground, and achieve 90-95% anti-squat? Do I need to mount the upper link on the rear axle higher, and make the front mount on the frame lower than the horizon?
You can achieve your desired anti-squat with a variety of linkage variations. I would suggest taking picture of your vehicle from the side and draw the lines. Then you can play with the lines on the screen and see what changes what.
Good work! #saved
IC at the end of the video in front of the vehicle.... how does it relate to AS not providing force to the front ? torque twist not a thing as there is no acceleration ?
It doesn't matter if the IC is in front of or behind the front wheel. The calculation is performed where the rear tire/IC line intersects a vertical line above the front axle. Look at the diagram.
Torque twist is more of a static response, not a dynamic response to acceleration. Roll center is the sideways dynamic response to fast cornering accelerations.
This is GREAT!
Mind if I share it?
I am interested in hearing more of your thoughts. RWD RC drifting is also one of these areas with a lot of myths floating around.
Of course! Please link as much as you like. I am hoping more people can better understand physics.
I have not dived into drifting very deeply, but now you have me interested.
I have been pondering this more. The tires in a drift car are slipping and spinning. The traction force would use the Kinetic coefficient of friction rather than the Static coefficient. Kinetic friction is always lower than static friction, so lifting the front end on a vehicle with spinning wheels will be tougher, though theoretically possible. I've seen drag race cars that are spinning their wheels and still manage to lift and even flip. This comes from massive horsepower and torque coupled with inertial downforce from the tires. You can't generate that with a typical drift or rally car. So technically AS would be in play on a drift car to a smaller degree, but it would also be largely unnecessary because the chassis stays level regardless.
Is anti-dive like a car with anti-squat but driving in reverse?
Yes, it is. I haven’t heard it described that way, but you are exactly correct.
From my understanding the more of an angle the shock is at makes it less effective because it’s simple ergonomics straight up n down is more efficient because the path is clearer & has no binding.
A shock should be mounted on spherical pin joints at either end, so there should not be binding in any orientation. A shock that is vertical produces less travel and higher spring force. A shock that is laid down allows more
wheel travel and has softer effective spring rate. It’s all geometry.
Your statement is true. However in a RC rock crawler that’s not the goal. No one is looking to achieve that instead we are looking to achieve flex. Full scale rigs would do the same if driving it like that didn’t suck. 🤣.
Flex is overrated
Slow crawler don't give a squat about anti squat as op mentions several times.
I also find it funny how he left out 2 of the most important factors of the equation, shock fuid and how it wrecks his his careful math and tire inserts/foam/ 3d prints complete change the grip and dive during acceleration
@@simonrenfort3410 Great ideas for future videos. Traction and inserts is a topic all on it's own!
For some reason this presentation is very nostalgic. :)
That’s funny. Might be the stock music I selected ha ha. I’m going to redo it very soon with audio commentary more like my other videos.
Everything you just explained was for a 1.1 vehicle that's driven from inside the vehicle. None of this transfers over to crawling an RC car.
This has everything to do with rc lol.. only issue I have is is definitely makes a difference when you are crawling slow.
How do physics apply differently based on your seating position? That makes zero sense.
@shaynejenkins446 The mass of the seating position is reflected in the CG location calculation. Sprung weight and CG are totally different on full size and scale. See 7:21 and 10:43
@@BoomslangSussI totally understand what you’re saying. I was replying to the guy that said physics were different for 1:1 applications.
@@joshuagregg7579 Thanks buddy!
Geometry, including anti-squat plays a part in slow speed rock crawling 100% as much as it does in go fast applications. Don't care how much you claim it doesn't, when it clearly does. There's perfect examples of it demonstrated
I'd love to see a perfect example of this. It would defy physics. Demonstrate it please.
Back that up with demonstrations/science instead of anecdotal information.
You're confusing rock crawling with rock bouncing. If you drive your crawler like a bouncer in order to clear a path then you missed the point...
@@laurentius1986 you are very correct, sir. I try to show the difference in the video between rock bouncing and crawling.
@CzarSoFar What exact physics would be defied by geometry doing what geometry does? There's examples of it on youtube. Geometry is nothing more than math, nothing magical about it, regardless of how little you understand it. Link positions change how a vehicle behaves, regardless of how fast or slow it's going. Can literally watch the rear end lift on a steep climb with a link riser, because this mythical creature called, geometry.
Interesting video but i found some bits hard to follow as the screen disappeared before i was finished reading or understanding and im not slow just not superman
And thankyou
I just went and fitted rear link risers on three of my crawlers 🥲
If it makes you a more confident driver, who am I to change that!
Great video easy to understand and at the End was even better YOO ITS U Jason 😊 much love from old friend/ridin bud ,, j@cOb. From. MH👍