When you go low upside down...

[moyesboy]

with a nitro and a governor:
Have you noticed that when you hover really low, like 6" upside down the ground effect is massive. The governor really starts to throttle the motor back and it sits there with not much negative pitch going strangely quiet.
The disconceting thing is the motor has to open up agan when you go to climb out, so it doesn't shoot up in the air as much - it climbs out of the ground effect and then needs more collective to keep it going.
Yuo don't get so much grond eeffect right side up.
Try it- the climb out from inverted at 3 ft, compared to the climb out from 6 inches.

My trex450 doesn't seem to react the same way - maybe the size of the rotor disc has somethign to do with it- there is more perimiter of disc for the air to leak out in proportion to the area - scale law.

[nightstalker]

Dont forget that there is no body of the heli below so its cleaner air and that means less pitch needed,
Sometimes when people have no gov and they go inverted and the throttle curve is set the same either way up that the head screams when inverted, so you end up lowering the curve less than you would when up right to stop the head speeding when inverted

[Sesame]

Ive often wondered why it seams the heli finds hovering inverted harder than when the heli is the correct way up.

I first saw it when practicing in Pheonix if you try it with the rappy 30. it hovers around quite happily the right way up, but soon as you go inverted the same model struggles, I thought it was just a thing in the program, but ive found the same with my little 450, not so much with the knight thats got oodles of power in any direction for a beginner like me

[Merlins51]

When you're inverted your centre of mass is above you centre of lift (i.e. the rotor disk) so you're naturally unstable and therefore require more effort to stabilise it.
When you're flying the the right way up, you have a pendulum effect that tends to naturally right the heli when you bank it.

That's one of the reasons why high-wing aircraft are used as trainers, because they're generally more stable than low wing aircraft.

[golddust]

....things can get expensive :-)

[moyesboy]

Regarding stability:
With the head speed wound up to 2000+ on a .50, or 3000 or a little 450 there is a lot of inherant stability in the rotor disc so I'm not noticing the pendulum sability reversal that much.
compare to a fixed wing its really hard to roll axially due to the distance of CG from the dics. There's a 3DNT in our club that rolls really nice, its a squat low profile thing with the OS90 mounted in the top so I guess that is why.

In Phoenix
The raptor30 is set up as sport and has less negative pich available than positive so it hardly climbs out of an inverted hover. you can edit that and make a variant with equalized collective pitch.

I never flew my heli low inverted before I got the governor, so I never experienced the resulting overspeed.

....things can get expensive :-)

Yes probably- I'm going out to drill my rappy into the deck tonight.

[robgt]

Which governor are you using Gordon?

Cheers,
Rob

[Sesame]

ive fitted and set everything up without any problems, but the thought of fitting this govenor for some reason fills me with dread and I really dont know why.

[simon_h]

....but the thought of fitting this govenor for some reason fills me with dread and I really dont know why.

Just do it. Put a Revlock 10 in my Evo today and have just had the most relaxing couple of flights for a long time. Really bounced about on the pitch and the headspeed just kept itself to what was required with no overspeeding on the way down. Just dial your selected headspeed and go fly. It does exactly what it says on the tin.

Simon

[robgt]

No reason to be worried - if you're unsure of anything, post questions.
The Governor really helps flying - it's one less thing to have to think about - the headspeed should be pretty much constant so you can concentrate on flying and know that the power you need at any time is there...

Cheers,
Rob

[colin n]

that ain't right.

there is no way that ground effect can change the engine rpm if the governor is working.!!

it does get less noisey however but only because u are probably nose in and the exhaust is faceing away from u.