Typhon Acceleration during crash?

[SniperGT-15]

Hi guys, I have a random question in regards to physics. Early today I was at an abandoned air strip scratching the itch for speed. My previous PB was 102mph with my standard Typhon running Hobby wing 4985 w/ 32 pinion 34 scorched spool. Now I made some modifications and I have a 34T pinion making it 1:1. Anywho, first run I achieved 99 mph being very conservative. Second run, 102 then 103 on the third run. Keeping in mind that the tank is getting low as the temps are climbing. I decided to make a final run…

This final run ended up with my Typhon becoming air borne and identifying as a gymnast. It crashed and I had to do the 1/4 mile+ walk of shame. To my surprise my gps read 107 mph!!!

Finally I reached the physics question. Can the gps report a false reading due to inertia created by the crash. I would like to celebrate this PB but the crash left some uncertainty. Hopefully the Arrma team can shed some light on the matter.

 

[Bustedaw11]

I mean I'm no expert but... I've always felt like it could affect it.. its a very good question.
I'm sure the answers will sway back and forth...
I saw a 74 out of my mini b in a crash that id only seen a 72 with before (same exact situation as yours) and I always felt like it had something to do with the spin/flip it did. *shrugs*
Sorry I couldn't actually help you out.

 

[J.Rambo]

Hi guys, I have a random question in regards to physics. Early today I was at an abandoned air strip scratching the itch for speed. My previous PB was 102mph with my standard Typhon running Hobby wing 4985 w/ 32 pinion 34 scorched spool. Now I made some modifications and I have a 34T pinion making it 1:1. Anywho, first run I achieved 99 mph being very conservative. Second run, 102 then 103 on the third run. Keeping in mind that the tank is getting low as the temps are climbing. I decided to make a final run…

This final run ended up with my Typhon becoming air borne and identifying as a gymnast. It crashed and I had to do the 1/4 mile+ walk of shame. To my surprise my gps read 107 mph!!!

Finally I reached the physics question. Can the gps report a false reading due to inertia created by the crash. I would like to celebrate this PB but the crash left some uncertainty. Hopefully the Arrma team can shed some light on the matter.

I think it starts to slow as soon as the car loses traction or loses/drops power. Kinda like a bullet. As soon as it leaves barrel, the bullet begins slowing down. If there was obstructions in the way, it'll slow down even more. In my opinion, you earned that 107mph! Enjoy that PB!

 

[rotauq]

Crashes make the gps readings unreliable i am afraid. Especially when you hit something (rapid decelaration, followed by choas) or go airborne
As for formal speedrun records, the car needs to be able to return.

Unofficially you can be happy with this amazing result. As long as you aren't contending for world record, nobody will argue the PB.

 

[loryriga]

nah it doesn't seem possible. there's nothing that can accelerate the gps during a crash, only things that can slow it down.

 

[Bustedaw11]

I have a question.
I'm in another dedicated rc speed run group. @Notorious J pointed out how a crash can possibly register false readings on a gnss. So these are the questions I asked and I'm hoping someone here has answers.
*copied and pasted
I understand that. That's very necessary if chasing records and it keeps folks honest. I was encouraged to speed run when K-Bash started those Senton speed runs and personally, all I wanted was to learn techniques and applications behind a speed run. He tried to hit 100mph with his Senton 8s build last summer but gave up and moved on to more suitable platforms. It's always been my nature that when someone says "cant" to find why and how to change that to "can".

I'm curious though as I received alot of negative comments regarding my 104mph. It DID crash into a cornfield at the end. How does it register a false reading?
I really wish the GNSS added more info or allowed both modes(track and drag) at once. I've been very curious which run up and down Colonel Sam Drive did I hit the 129mph? I really wasn't watching my phone and was just practicing what another friend in AF told me about slowly easing into throttle(I used to just jam the throttle back). All I can say is one of 6 or 7 passes registered 129mph and I have to assume it was one the the early ones as battery only got weaker, right?
My next attempt a few days later saw me swerving and kissing a curb after going airborne at the end of my run when I hit the elevation change at the bridge.

But what you said has me curious. I KNOW the gnss isn't infallible, I had to replace my second one after EVERY SINGLE run registered 41mph no matter what. Is there a way to calibrate them to ensure effectiveness? Test for accuracy?Btw, that's how I crashed into the cornfield with the stock body and specs(at 104mph). I was watching the speed climb and not where rc was going lol. Same crash is where I lost my first gnss and 2s lipo.

It really comes down to if you are doing this for yourself or to prove something to others.
If you want to prove to others then you have to play by the set rules which state runs with a crash do not count.....

When flipping and rotating there could be a sudden rotational acceleration that gives the GPS a false speed reading.
No solid ways to calibrate or do anything with the GNSS and thank god because people could then poorly calibrate them to falsify their speeds.

Best thing you can do is try again! The better way to confirm speeds is to put a GoPro Hero inside the car and you can watch the speeds right up until the crash. Example of my recent run with the GoPro hero5 blk telemetry data added to the video.

Thanks. I hadn't considered that spinning or rotating could do that and it makes sense. I'm far too new at this to consider chasing records. I accept my name won't be mentioned in the same sentence as Raz, Omar, McCoy, vwturbowolf, or even Notorious J.
Like I said to other guys above, it's more personal and a learning curve for me. The folks who doubted the 104mph are entitled to their opinion and I've nothing to prove to anyone but myself. Incidently, all I can say for SURE is I watched myself surpass 100mph before another friend shouted something like "watch it" and by time I looked up, I was seeing it flip into the field. Even with the crash, the adrenalin rush was worth it!
One thing I love about this Forum is that many take the time to explain the science behind the "why". Like when @jkflow explained exactly what caused brownouts or @jondilly1974 explained why easing into throttle yields better results. Understanding why is very important and these are just two examples. I've learned so much from so many, including you.

Keep in mind, there is no internal component that impacts the speed reading, as silly as that sounds.
This is all based on received data from the satellites and internally comparing the timing between those signals. That is just the principle of GPS/GNSS in general.

2 sources could generate this inaccuracy, to my knowledge.
a) Weak or loss of signal and, believe it or not, the general randomness of signal processing.
Now of these 'consumer' devices it is possible that a low signal can be misinterpreted, signal loss is simply due to the antenna being out of line of sight while your rig cartwheels or tumbles. GPS/GNSS are only 99.99% (or thereabout) accurate and can and will be way off during 0.01%. It happens daily but most you will not notice.

b) GNSS can be accurate to 1 m (3 ft), now if your 4ft rig starts rotating at an insane speed it could be misconstrued as forward motion.

Keep in mind all this is toy grade, there is no application that only relies on GPS/GNSS alone, if it truly matters, would be fatal.
In most cases, though, it's 'good enough'.

There is a reason why true world record attempts still use optical devices, because you can never be 100% sure, just 99.99%

Found this discussion on here from a while back, thought I'd share lol.

https://www.arrmaforum.com/threads/speed-runners-how-fast-did-you-go-today.24467/

 

[RuffRiki]

I agree with @rotauq. I’d be happy with the speed deep down but in the world of speed runners it doesn’t count if u crash. You should be able to drive it back or go get it if you can’t see it to make a turn.

 

[rotauq]

nah it doesn't seem possible. there's nothing that can accelerate the gps during a crash, only things that can slow it down.

Fysically you are correct, yet the gps itself can misregister datapoints during the crash making it believe it went faster than it did...