Discussion - Flying CCPM heli for first time - is this correct?

[Chiz]

Hello

I'm building a Dragonus II helicopter.

I've got a Spektrum DX7 radio. Now I've only flown a fixed pitch Honey Bee helicopter which I'm flying reasonably well.

I'm spending plenty of time on the Phoenix simulator with the radio before I attempt to fly the Dragonus. The kit has not arrived yet anyway so I have plenty of time.

Channel 1 controls throttle, channel 6 collective pitch.

Now can you tell me if this procedure is correct for a real helicopter. It works well in the simulator but I'm not too sure. I've deduced all this for myself and nobody has shown me the correct procedure so I'm sure I might be doing something slightly wrong.

I've found that if I leave it at the default setting - throttle goes from 0 to 100 and collective goes from 0 to 100, I can not hover upside down because the throttle drops too much.

So this is my procedure

1) Set the throttle so that the minimum is 25% and max is 75%
2) Set collective so that the minimum is 0% and max is 100%
3) With the throttle stick at bottom, turn on throttle hold switch so that it spins up to 25%
4) Now fly the helicopter as usual

Is this the correct setup and procedure for a real helicopter?

I'm using a linear throttle and collective curve, I'm not ready for advanced throttle curves just yet. Although I do realise a linear throttle from 25 to 75 is technically a curve.

Also I think I should be setting throttle from the radio itself and not the simulator since I'm going to need to do it that way with the real heli right?

Thanks

[3dbasher]

idle up

[Chiz]

3d

"Idle up" simply puts a cap on the low-end of the throttle right? Which is effectively what I've done.

I think I should setup the 3 available flight modes (and just use the first 2) and set throttle to be 0 at the low part on the first flight mode, and say 25 on the second flight mode.

I can't experiment at the moment since I'm still waiting for a charger for the radio.

Is there a FAQ on idle up and flight modes?

[3dbasher]

basically you've gotta match the throttle to the load on the motor/engine to acheive a constant rotor rpm... so more collective more throttle wether its postitve or negative blade angle.
leave your pitch curves linear in all flight modes, then i idle up set your throttle curve as follows L100 p2 75% p3 50% p4 75% h100% for the sim only of course

[gazza]

Regarding real helicopters I can only speak for the Chinook.
The throttle is basically a Two position lever with a ground mode and an air mode.
Ground mode is for spooling up and down and air mode.....Self explanatory
The throttle in air mode (100%rpm) is governor controlled to maintain constant RPM of the blades (225rpm) through the changes in collective/Cyclic pitch during flight and the collective is an entirely seperate mechanical system and is not linked to the throttle in any way.

[Smoothound]

Gazza,

I think you may be taking this a bit too seriously...

When he says real helicopters, I think he means REAL RC helicopters not REAL Real helicopters ie not the toys that many model shops now sell as RC Helicopters

[moyesboy]

The radio has a switch which changes between flight modes.
when in normal mode you set it so throttle stick down gives you a little bit of negative pitch and the throttle closed.
you need a little bit of negative as it spins up to stop a gust of wind lifting it or tipping it.
Yuo must not have full collective negative with the stick right down to start with or you will hit the blades on the tail boom when you land heavily.

when you fly aerobatics yuo switch to another flight mode with the blades already going round.
Then you get +10 degrees (for example) of collective with the stick right up with full throttle, zero degrees with 75-80% of throttle with the stick in the middle and -10 degrees and full throttle with the stick right down.
you don't use this setup for first flights because you can plant your heli into the ground very hard accidentally with full negative pitch.

for first flights you should setup all your flight modes the same so it doesn't matter which position the switch is in the heli will fly the same (less to go wrong then).

On your little heli you want to have the throttle so you get 2400 rpm at zero degrees, then make the throttle increase in a straight line from there to 100% at full pitch. Alternatively use a governor setting if your ESC has one.

If you have ambitions to fly upside down etc, then you can start with zero degrees at mid stick and say minus 2 degrees with the stick right down. Then you hover at 3/4 stick rather than half stick, like you need to to be able to hover upside down. but it makes the stick more sensitive because you only use half of the range flying right way up.

go to helifreak.com and look in finless bobs tech room for the trex build videos and there all about ccpm setup will be explained.

[gazza]

Gazza,

I think you may be taking this a bit too seriously...

When he says real helicopters, I think he means REAL RC helicopters not REAL Real helicopters ie not the toys that many model shops now sell as RC Helicopters

I knew that I just wanted to talk about Chinooks
Note to self...Must read things properly

[Chiz]

When you fly aerobatics yuo switch to another flight mode with the blades already going round.
Then you get +10 degrees (for example) of collective with the stick right up with full throttle, zero degrees with 75-80% of throttle with the stick in the middle and -10 degrees and full throttle with the stick right down.
you don't use this setup for first flights because you can plant your heli into the ground very hard accidentally with full negative pitch.

Thanks moyesboy

You've explained it perfectly. In the example above, for the 3d flight mode, I'd use a throttle curve of:

Low 100%
Int 87.5%
Mid 75%
Int 87.5%
High 75 %

That right?

Obviously that gives me a V curve.

For normal flight, like flying a fixed pitch heli:
Throttle:
Low 0%
High 100%
(linear curve)

Pitch:
Low -2
High +2
(linear curve again)


I realise these curves are extremely simple, just want to get started first.