How to avoid flying behind the power curve.

[THI]

I tend to agree with Eben (on the non-turbo engines )

Will this not eliminate a lot of the "surprise" when using a non-turbo engine?

Surprise like in "I now need the turbo to get me out of this mess, oops, I don't have a turbo

[saraf]

Ek wou dit nie in soveel woorde se nie, maar nou toe , ek het vir jou n lekker een met 120h op die clock.

Dan is jou probleme op n einde.

Groete

Eben jnr

[t-bird]

Hi THI

On non Turbo engines it will work the other way round.

You will set your pitch on your prop at the coast and it will be too course at altitude less power at altitude.

If you set your prop pitch at altitude you can over speed the engine at the coast more power at the coast.

[saraf]

Die krag om jou uit die moeilikheid uit te kry le in die Torque van die engine en nie die Kw nie.

Kyk die verskil tussen die Subaru en die Rotax

The 2.5-litre
engine delivers a powerful 126kW of power at 6,000rpm and 229Nm
of torque at 4,400rpm.

[Learjet]

SARAF wrote

I do not have allot of experience...

haha SARAF you are too humble - I don't think there are too many okes in the Cape with more flying experience than yours!

As for engine power comparisons... ja well no fine... but then you need to look at the relative weight (and drag etc) of the engine & aerie in order to assess overall performance.

This monster generates over 108,000 HP at just 102 RPM. But weighing in at 2,300 tons (the crankshaft alone weighs 300 tons) I don't think it's going to get anything airborne anytime soon. Even at the coast!

[saraf]

Ja ja , dave ,

Put to big enough wings on that sucker , a big enough prop and she WILL FLY......

[THI]

Ja ja , dave ,

Put to big enough wings on that sucker , a big enough prop and she WILL FLY......

Surely you mean big enough rotor

[MPL Pilot]

Grapkas!!

If I may add something to "flying behind the power curve" on final.

Quote
The reasons for these accidents are usually

- Down drafts
- Density altitude
- A dramatic change of the wind direction
- Rotors over obstacles
- Engine losses power out of ground effect


During training at Wagtail I found myself with the airspeed falling away due to gusting winds, after that incident I had with oom Johan during early hours of training, (we ran out of airspeed and had a hard landing). Since then I made a habit of keeping an eye on the airspeed indicator on short final and during the float before touchdown. This has helped to diagnose and avoid dangerous situations especially with wind gusting just before touch down.

[t-bird]

The idea was to talk about flying behind the power curve.

The turbo not kicking is was an example.

Same as the pax who looked a lot lighter the previous evening after some refreshments.

Gyronaut also pointed out that wet grass strips can have a negative effect on take-off performance

You can also have some mechanical problems.

All of above have an effect on the performance of the gyro on take off.

Rolling on the runway and flying in the ground effect is not flying behind the power curve.

When you decide to fly out of the ground effect at too steep an angle without the necessary airspeed then you have done it.

HOW NOT TO DO IT ?

AIRSPEED , AIRSPEED

divide the runway in quarters and when you do not have the necessary speed at 3 quarter abort.

And Eben suggestion to fit a 800 hp turbine to a RAF or fly at Upington with an unlimited runway

OTHER SUGGESTIONS ?

[OzGyro]

Hi All

Ok here is my 2 cents worth in regard to this matter. There are only two things you really need to have to avoid any of this, good airmanship and airspeed. At the end of the day one has to avoid getting in a position of being behind the power cure, this is primarily avoided by good decision making which in turn comes down to good airmanship.
We can all blame wotever factors we like, DA, turbo issues, weight etc.
Something I would like us all to give thought to, the last time you rocked up to the airfield to take a mate for a fly did any of you do the following?
1 - Preflight the aircraft
2 - Go for a solo flight first to get a feel for the aircraft, the surroundings and the factors affetcting that given day. I doubt very many of us have done it, if ever.
From what I have read and witnessed most cases of guys getting into trouble is when they are flying two up, the new generation of gyro has made it very easy to get into the air in good conditions and has probably even made us a little bit lazy in some regards. If you need a 914 turbo on boost to take off at the coast then you are probably doing something wrong.
I learnt to fly in a fully enclosed two seat machine weighing 250kg and with 27ft rotors add to this my instructor at 85kg and me at 95kg, ok no real issue you say. The real factor in this is the fact that this machine was powered by a 2 Stroke Rotax 618 add to this that the pre rotator was only capable of giving us 120rpm and the suddenly you begin to understand what rotor management and airspeed/groundspeed is all about. At approx 45 - 50Kts we would rotate this gyro, keep it slightly nose down and remain in ground effect until we accelerated to approx 60Kts on the clock, then and only then we would begin the climb. Learning to fly in what you call a marginal gyro teaches you lot and makes you understand and respect the Power/Drag curve.
There is an old saying - Complacency/Familiarity breeds contempt - How many of us have been guilty of this? I know I have.
Of course this is just my humble opinion. Safe flying to all.

Cheers
Darren

[t-bird]

Hi Darren

If your turbo does not engage on a 914 then you have a 912 ul which is 80 hp. The 618 's power to weight ratio is a lot higher than your 912 with the dead weight of the turbo.

You have lost 35 horses of 115

I agree with your rotor management principle and airmanship

[Wagtail]

Hi all,

Ebie, not wanting to get on your back, but the way I read it it sounds as if Torque is the important one and not Hp. ...this is not really true. Hp is the important number not torque....now while everybody sits up straight let me explain.
The formula to convert torque to horsepower is Torque X RPM) / 5252 = Horsepower.
Physics : Torque is a force, just like weight.
Hp is energy. Forces can be multiplied, devided split....
Energy can be converted, fuel to Hp, nuclear to heat to electricity and so on.
For a gyro to climb, it increases it's POTENTIAL energy ( it gets higher and higher ). Energy can be converted, never "created" or destroyed, so to climb you need to convert something :
Fuel converted into heat, converted into linear motion ( piston ) transfered to circular motion ( crankshaft ) converted to thrust by the prop accelerating a certain mass of air and so on.
Bottom line, it is the energy that gets you out of the tight spot, not the torque.

There is an old saying that you need torque to swing a big prop....no, not COMPLETELY true. with 0.00001Nm I can swing a 12 m prop...just very slow, but with 10 000 Hp I can swing that same prop and make a lot of wind......just tell me what the diameter is, I calculate the tip speed and then I calculate the RATIO of the gearbox to give the required tip speed......
The gearbox ratio will ultimately determine the torque transferred to the prop.

Luckely the Subaru has the Hp based on the torque and the fact that that torque is available at 5000 + rpm.

Enjoy the flying down to the coast, just keep an eye on those Subies while parked in Stellenbosch....I will have enough space in the Kriek to bring back two engines.....

Regards
Wagtail

[saraf]

HI Johan

NIce to hear form you again.

No problem, I am aware of the fact that the Hp is one of the contributing factors , but thanks for explaining that to all.

But like you said: " Luckely the Subaru has the Hp based on the torque and the fact that that torque is available at 5000 + rpm."

Ek hou jou dop daar op stellies met n vlak oog,

SIen julle daar

E

[t-bird]

Eben

And power to weight ratio of the subbie compared to the Rattax 914 ?

[M I Claase]

If you fly a gyro you will be behind the drag curve at least twice during any sorty and that is just before take off and just before landing! During take off you have to get in front off the drag curve, with airspeed, to fly and on landing you have to get behind the drag curve to stop flying! So ther is no way you can avoid it.