How fast can a RC boat accelerate ?

[Himalaya]

FAIL. hehehehe

6.26 seconds to 354 km/h - ProStock on gasoline.

So how long does it take to do 0~3kmh?

[7500RPM]

FAIL. hehehehe

6.26 seconds to 354 km/h - ProStock on gasoline.

Pro Stock is the BEST, No turbo's, blowers or NOS,
These cars launch the hardest than any car out there!

[Fluid]

You can't possibly accel 0-100kmh faster than 2 seconds on tires unless driven by jet power...

FAIL. hehehehe

6.26 seconds to 354 km/h - ProStock on gasoline.

[7500RPM]

I think you better look at Top Fuel Dragsters, 0- 300+ Mph in under 5 seconds! 1320 feet

This part from Wikipedia:

A top fuel dragster accelerates from a standstill to 100 mph (160 km/h) in as little as 0.7 seconds (less than one fifth the time required by a production Porsche 911 Turbo to reach 60 mph) and can exceed 280 mph (450 km/h) in just 660 feet (0.2 km). This acceleration subjects the driver to a maximum force of about 5.7 G.

To put these speeds in perspective, if you were traveling at 200 mph and crossed the start line at the same time as a Top Fuel car got the green light, you would still wind up losing the race at the end of the quarter mile.[1]

[Himalaya]

Yes you are right that's an impressive push, especially when considering they were powered by prev.gen. batt tech.

You can't possibly accel 0-100kmh faster than 2 seconds on tires unless driven by jet power. Traction and weight are always fighting against each other. Fortunately propellers don't have this limitation, making 1.x seconds accel possible which I never imagined can be so amazingly fast.

[NativePaul]

I think 0-85 in 3.1s is still faster than you can do on road tires.
Have you looked at what they do in Thailand? they love their R/C boat drag racing over there.
clip
john-tom.com

[Himalaya]

Well you brought up an interesting point to discuss. Here's a typical accel curve from a test on a BMW 5. Reading the curve it's pretty clear that 0~3kmh took 0.2s; 3~50 took 2.1s. Not even close, 10+ times apart actually.

In real world most if not all accel curves show a steap and linear starting section, the linearity will last for some seconds while the max torque is still the limiting factor. After that the accel slows down second by second because the engine is approaching its max power and the air/water resistance increased dramatically as the speed goes up.

I do agree with you though that accel from a dead stop does take a little bit more time, for a car the tires need to establish their grip/traction; for a boat it should be careful not to jump off the water, losing thrust.

[Fluid]

You cannot compare the acceleration of your cat (awesome as it is!) with a car - if you start from a rolling start and the car starts from a stop. The slowest part of any acceleration is from 0 to 3 km/h and you will find that 0 to 3 km/h can take as long as getting from 3 km/h to 50 km/h. Inertia is a powerful 'force'.

We have done some FE drag racing in the past - another Texas club tried to get it going as a regular event but it failed. With our oval race boats from five years ago - NiMH power and all - I believe the fastest anyone in our club got was 3.1 seconds to 85 mph in 165 feet from a dead stop.



.

[Ub Hauled]

I like your approach... accel is def not seen often in debates here...

[Himalaya]

Good day guys.

Not sure if this is a new topic for at most time we talk more about top speeds. One day as I was glancing my Eagletree GPS data and had some interesting findings. The data was acquired with THIS HPR115 cat.

Here are the graphs.

Obviously just speed runs back and forth, boring to read. but when zoomed in it looked different. From the graph it reads 1.6s from 0~100kmh, 2.2s to 120kmh. To my knowledge this is faster than any super sport cars, even Bugatti or Lambo. And it's so simple to gain this, just pull and hold the trigger.

Looking closer into the graph we can tell that the cat did not start from absolute zero speed, it was drifting with a speed of roughly 3kmh. It took 1.5s from 3~100kmh, so the average acceleration would be
(100-3)*1000/3600/1.5/9.8 = 1.83G

I have to say I was pretty surprised about how hard the props pushed my HPR115. Thought this could be another interesting way of boating besides top speeds.