At crazy high RPM more weight provides some inertia. I do agree.

Speed records belonged to low weight Banshee and TDR.

In general high RPM is very spectacular, noise and fun.

In my opinion it is far from optimal due to:
- excessive stress on parts
- high currents which increase exponentially with RPM
- need for expensive electronics e.g. $800 200A Kontronik ESC.
- need for expensive 60C lipos

I did not replace any parts in my 800 for over a year. Hundreds of flights...

I know my flights are not spectacular but I have fun.

 

Thats right. I still don't know what you're getting at. First so talk about how there is little need for complex, high performance designs, then you start referencing videos of heavy helicopters smacking hard and saying there's no need for larger diameter main shafts, then you talk about how light helicopters are the way to go and now you start suggesting the 2 stage, high performance designs are the way to go?

 

Christian, designer of Oblivion 300 sent me a link to the video. There is 250 with extended blade gripps (low disk load). It behaves awesome:

 

Is it low disk loading or compensating for the high disk loading of the original helicopter?

 

Both. It can fly much better than original T-Rex 250.

 

Exactly, like I said before there is an optimal disk loading. I believe the trex 250 stock has too much disk loading which is why the extended blades helps. What will be interesting is flying the stock and extended versions in a considerable amount of wind and then see which one flies better.

 

Optimal disk load is 0 kg/m2. Imagine smak 3D with heli which has no weight at all.

Did anyone try hydrogen tanks?

You probably ment mass not weight...

 

Mass = Weight, Force = Mass x Acceleration: basic unit of mass is a kilogram
Simon

 

Confucius say: If it no have mass and take up space- it not matter. (Insert physics pun here)

 

Mass does not = weight, weight is measured in newtons while mass is measures in kilograms, weight is mass times acceleration due to gravity.

 

You say 0 weight would fly amazing, I don't agree with that. A 0 weight machine would fly in a very unusual way.
Think about this, for a heli to hover Fnet must equal 0. A weightless machine will hover when there is no thrust because there is 0 newtons pulling it down and 0 newtons pulling it up so it stays still.
If a gust of wind hits this machine you would have to flip the machine 90 degrees to counteract the push of the wind so if you wanted a stable non-drifting hover in this 0 disk loading machine you will need to fly it on the side like knife edge the whole time. Imagine you were to fly at a F3C competition which requires you to land after every hovering maneuver. You need to take off and immediately flip or roll 90 degrees to keep the heli in the same spot due to wind and you will need to bring the heli really low in knife edge before suddenly flipping it 90 degrees to land after the hovering maneuver. In a heli with considerable disk loading you would simply redirect the thrust slightly to counter the effects of wind as there's lots of thrust to counter the weight.

 

Are you going to say that flying smack 3D looks "usual way"? Did you see any full scale heli doing tic-tocks?

800 can easily hover pulling 40 Amps. Did you wonder why many put 160A ESCs in 700?

Look what Jan Henseleit wrote in TDR manual:
"For the same flight condition „Hovering at one position“ 570W is required at 1300 rpm at the rotor and at 1850 rpm you already need 1000W. At more than 2100 rpm 1500W are required, i. e. nearly the triple amount, although you do nothing more than hovering."

Do we really need 20kW motors in 700 class helis?

My 800 was able to reach 197km/h with 4.2kW motor.

This excessive power is applied to minimze gravity influence on heavy airframes.

Zeppelins were "weight less" and not particularly twitchy. Aerodynamic resistance and gross mass counts in that case.

Put Hindenburg on a scale:

This monster was floating in the air. Scale would show zero kg.

 

So you believe a helicopter hovering with its rotor perpendicular to the ground is fine?
The additional power draw in the higher and higher headspeeds is due to the increase in air resistance as the relative airspeed goes up.
Regarding the large ESCs in 700 size helis I have attached a castle log file of a 3D flight. You can view the logs via the castle log viewer software available for free download. You will notice that the current draw is not at 160 amps all the time, most of the time it is below 50 amps on a 700 size machine. Large ESCs are required for the high peaks in rapid direction changes and these peaks will not get much smaller in a apparent weightless machine as the mass is still there because F=MA.

 

Looks cool...

 

*Popcorn's Ready*

 

Do we really need 20kW motors in 700 class helis?

if you have to ask this question you will never understand the answer

 

Please show us your skills. More power will not make you a better pilot.

Can you do piro tic-tocks with old Rex 600 ESP on 6S?

Emil can:

 

I did not see any piro tictocs in that video. Maybe you posted the wrong one?
Anyway, here's just a lazy flight over the water. I don't think anyone filmed my freestyle rounds at 3DX last year.

 

Heres a video of me flying something thats not that overpowered. Synergy N7 nitro

 

A flight on my own machine from a while ago with a setup you definitely wouldn't approve of. Monster 4530 Scorpion motor and 5000mah packs on a Kontronik Helijive but still take note of the flight time and and overspeeding auto at the end which would be very difficult on a low disk loading machine. 4:00 minutes of almost unlimited power is good enough for me.