Less Rpm=more Lift

[sirlandsalot]

I have always beeped the RRPM up if able for heavy lifts. I have also heard that if the rotor RPM is a tad slow, you can get more TQ therefor better lift??? any idea's on that

[epicyclic]

the old 204 myth

[Over-Talk]

Don't try this with a 212 (or a 205 with a 212 rotor system).......that rotor design doesn't like this.

 

Don't try this on a Hughes/MD 500.......their tail rotors stall if they slow down too much.

 

I have tried this on some models (within Flight Manual limits, of course). I found the lower RRPM lowered the torque...but it also lowered the lift. So then I had to raise the collective which brought the torque back to near where it was originally.

 

Now that I am older (wiser??) I leave it at 100%, and if it doesn't fly I put it back on the ground.

 

Just imagine your family is taking a sightseeing tour and some pilot is using this sort of technique to get them in the air. AAARGH!!

 

Just say NO. It's a lot more professional than beeping-down the RRPM.

[Outwest]

Remember, torque and RPM are not related.......you can have a huge amount of torque with zero RPM. Think about taking a bicycle and putting the front wheel against a wall. Now stand on the pedals.....lots of torque. Any RPM?

 

The only thing that gives you torque is good old fashioned horsepower.....there is no substitute for ponies

 

Some rotor systems do provide more lift at low speed with RRPM less than normal cruise value, the S76 being one of them. Nick Lappos gave a very good explanation about this in a post on another forum a few years back. He explained that when they design a rotor system it is all about trade-offs. Good lift in the hover vs high speed cruise. You can have a very efficient rotor system that will pull stumps, but will only be able to do 60 knots and vice versa.

 

As to the comment about the 212 rotor system, although it is a different airfoil than the 204/205, it is the infamous torque (HP) limiter that has it settling out from under you if you droop it off, not the rotor system.

 

[Helilog56]

Hmmmm......I wonder how many RFM's state to beep down Nr for extra lift?

 

In helicopters........RPM = life.

[Outwest]

Hmmmm......I wonder how many RFM's state to beep down Nr for extra lift?

 

As far as I know, only the S76 during OEI.....but the S61 is approved to droop to 72%, that's 146 RPM during rejected take-offs

[lamanated]

Remember also that unless someone has checked the RPM's with a strobex etc with digital readouts, you can never be assured the gauge is correct. I've never seen a jetbox or a 500 with one that was dead on, and none over read

[407driver]

Hmmmm......I wonder how many RFM's state to beep down Nr for extra lift?

 

In helicopters........RPM = life.

I'm with Dr Bob on this one. In theory the airspeed is exponential in the lift formula

[gwk]

The 412 in cruise responds positivley to having the RRPM reduced, which also requires you to increase the TQ slightly, and I beleive that it approved by the manufacturer, but I,ll check.

 

As per pre descent checks, RRPM must be returned to 100%, prior to final descent.

 

I,ve played with lowering it on the 204, and felt the same, if it,s that heavy, make another trip and let someone else be the hero!

 

As for the 212 and TQ limiter, obviously designed by a knob who never had to fly the thing, I,ll bet that one item led to more accidents than everything else on the 212.

[sirlandsalot]

Hmmmm......I wonder how many RFM's state to beep down Nr for extra lift?

 

In helicopters........RPM = life.

 

 

Well that is the way I have always been taught, I agree completely A guy told me this, whom has very high time on the line, I do listen to the high timers however I do have to choose what to believe. I have never heard of reducing RPM to get more TQ to get more lift! seems like a crazy idea, THAT is why I posted this!!!!!

 

I would think reducing RPM reduces airflow which reduces lift?? I am not askiing either for an answer like take another load, I have no problem at all telling any client" if you don't like it, carry it yourself" That is not my question here.

 

the topic came up talking about astars and setting the RPM, I couldn't even beep it down if I wanted, and the last thing in the world I want particularly in a 350, is low rotor!!! I Respect what this guy tells me but I question this.