Yeah but the fastest board in the world cant even beat an anolog popsicle skate off the line though.
In your picture it shows 64 km/h by GPS. So maybe something is wrong by the gearing or GPS might reacted too slow. But please post that video, would be interesting. Was that a flat street or slightly downhill?
But 64 km/h = 39,8 mph
68 mph / 39,8 mph = 1,708 factor
For double the speed you need 8 times the power (2 x 2 x 2) but we only have 1,708 times the speed it would be 1,708 * 1,708 * 1,708 = 4,98
1742 W * 4,98 = 8675 W
8675 W / 740W = 11,7 hp
for 96 mph it would be
96 mph / 39,8 mph = 2,41 factor
2,41 * 2,41 * 2,41 = 14
1742 W * 14 = 24388 W
24388 W / 740W = 33 hp
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If you enter 6 Sq/Ft in that calculation you get 33hp as result. No idea what is right. In my runs i never use the speed tuck or try to be aerodynamic.
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A typical motorcycle has a 3.4sq’ frontal area for a reference example.
Why are you guys looking at cars and motorbikes??? This has all been done before. The equation below takes into account all drag (including frontal pressure and skin friction drag) as it is based on experimental data.
Dusts off experimental windtunnel aerodynamics book
Drag of a human
D = Cd * (vH/S) * q q is based on airspeed and at 61.36mph ,it is 9.0lb/ft^2 v = volume of body H = height of body S = surface area of body Based on 16 subjects, the vH/S value varied from 0.65-0.82ft^2 with the mean at 0.72ft^2
Cd of several positions: Standing face forward 12 Standing sideways 5 Sitting forward 7.8 sitting sideways 4.5 squatting face forward 4.3 squatting sideways 3.5 So I assumed 5 for Cd.
Therefore at 61mph… D = 32.4 lbf
Converting to metric yields… 3.93 kW
Now all that is needed is rolling resistance force and the power required to move someone at said speed would be approximated
At 20mph, D = 3.6lbf Power = 143W
So 27 times the power, nine times the drag force at thrice the speed.
So its a cubic relationship which makes sense and is what @ackmaniac was saying before
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dusty book, sounds like old data… what is the position, the publish date? just saying if you really want to get all science and you don’t know both and the latter is more than about 3-4 years i’d be looking for a new source 
it really depends, but here’s a question I need you to answer first…
Do you plan to take the autobahn on your daily board travels and also, do you value your life?
Personally for daily travels and just cruising around 25-30mph is good enough with good margins for me.
@Cobber Found this, sadly all the measurements are with leathers on. Is 2010 a relevant enough age source 
Here is the article, quite an interesting read: https://www.researchgate.net/publication/229401390_Downhill_skateboard_aerodynamics
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As far as I can tell, the numbers you provided only represent the power required for wind resistance. I think another 10-20% more power would be required for losses at thr motor, trasmission and to rolling resistance.
From my own experimental data Ive found that it took me 4000 watts to hit 49mph.
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You do know all airplanes are based on data from the 1950s right? The best delta aircraft (fighter jets) models are based on wind tunnel data from the 60s…
CFD models are based on experimental data from the 30s-70s. The reason is that back then they did not have the computational power to do models and therefore they had to rely on experimental data which is much more expensive than running CFD on a computer these days.
Also physics doesn’t change over a course of 50 years…
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Correct! This is purely the power that is needed to overcome drag due to air.
What isn’t taken into account are the following:
-Rolling resistance: The other main source of drag. To experimentally determine it you would require your board, some weights, a fish scale and someone to pull steadily. You can then pull around however much you weigh on the board, and see how much force it takes to pull it at a constant speed. This number should not vary with speed if I remember correctly. What will affect it is the wheel material and the surface that you are riding on.
-Losses in your gearbox: Whether it is a direct drive or a belt drive There will be losses in transmitting the power from your motor to the wheel if gearing is involved. This does not apply to hub motors since the essentially are the wheel.
-Losses in your motor: This includes copper losses and iron losses from the magnets. I’m not going to even pretend I understand this, as magnetism is black magic to me.
-Losses from your ESC: Any losses incurred in the fet switching and powering of all sensors and stuff associated with the ESC
-Losses in your battery: This includes electrical loss due to current transmission and chemical losses from the reaction inside the battery. Yes, your battery also has losses!
What we see measured by the ESC as power (Voltage x Current) is the electrical power going into the ESC and already takes into account battery losses. You can kind of estimate the power coming out of the ESC by taking the RMS Voltage and Current but if I recall that isn’t always too accurate. Most ESCs operate at 90% efficiency. Motor efficiency for an outrunner is usually in the 80-90% range at peak efficiency and I know planetary gearboxes are somewhere in the low 90s at peak efficiency, I don’t deal with belt driven setups at work so I cant say what their efficiency is, although I imagine is similar. So you could assume a ~70% drivetrain efficiency, 60% if you want to be conservative.
Was that at a constant speed or while accelerating? Those two will differ. You could try going at a constant speed at several speed, eg. 5, 10, 15, 20, 30 for like 30 seconds for things to stabilize and then a cubic curve could be fit and extrapolated to define a model for you and your board.
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It was still acceleraing but pretty darn close to the drag limited top speed. Heres the video, speed starts flat lining.
Here is a shreenshot at topspeed.
0
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That was awesome btw, pulling 130-140 batt amps at times 
Also noticed you were getting pretty close to thermal throttling on the vesc, what’s your cooling look like?
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That’s crazy! Were you even tucking??? If only we had empty streets like those here…
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No real cooling actually, I use FOC box’s and they are mounted within the enclousure. I rarely break 35mph so its not much of a concern typically. Im putting these motors on a bigger battery and it should easily break into the 50’s. Unfortunately that closed street I test on is only 1/4 mile long so Ill have to accelerate harder at low speed which pushes my vesc temps up even faster if I want to break 50 and still have room to slow down in time.
@PXSS
I am tucking as best a 270lb guy can lol 
The street is empty because they permanently baracaded it on both ends to prevent cars from taking shortcuts through the neighborhood to avoid highway traffic 
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I’ve got an almost mile long silky smooth top speed test track outside my front door that I’m going to test the v4xls on 
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I dont think youll need more than a few hundred feet to hit top speed on the XL’s! Those should accelerate hard! I cant wait for the XL’s either
Several things I want to try, 2wd rear, 2wd fwd, 4wd v4xl front/6374 190 rear, 4wd v4xl rear/6374 190 front
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Yeah Ive seen you mention a few of those before, cant wait to see your results!
After the sucess Ive had with the AWD V3’s im just going strait for AWD XL’s. The AWD V3 board is easily the best balance of speed, accerlation and efficiency Ive experieiced yet. AWD XL FTW!
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