Xenon Gyro

[t-bird]

28-29 Inches of boost in the cruise.

[FO Gyro]

My power setting at 80 is 5200 rpm (I have never flown another gyro) so would love some input from the Magni Ela etc etc guys?

Eagle 1, just out of interest, my MT-03 at 5000 RPM, 28-29" on the Highveld sits at 95 mph (1 up only). I'm actually not sure what our rotor length is. Two up, she sits at 90 mph at the same power setting. At 5200RPM, MP about 30-31", she flies at 105 mph, but that's actually beyond Vne. I still don't understand why Vne on the MT-03 is 100 mph. Seems a little too conservative.

Longer rotors, for the same rotor RPM, will give a higher tip speed. The induced drag from angle of attack might be less, but the form drag will be higher, hence the reduced resulting cruise speed.

[Gyronaut]

FO (or should that be Senior FO?)

Thats impressive performance. I'd be keen to know what your rotor RPM is under the conditions described (1 up 90mph/5000rpm/29"map vs 2 up 105/31") ? I have found that the heavier I am the higher my rotor rpm is for a given altitude and speed. Strangely, I have been unable to link rotor rpm directly to engine rpm or manifold air pressure. Will monitor next flight.

I agree with you that the VNE seems low on your machine for the cruise speeds you achieve at those power settings. When do you get to use your turbo then?? :D . I have exceeded the VNE on my machine several times intentionally and find that all that happens is that it starts to shake/shudder. [Yeah yeah I know this should only ever be attempted with a ballistic chute and all that... Dont start Brian!] I believe shudder is because the retreating blade (closer to the hub) is actually slower than the forward motion of the aircraft and therefore creates reverse airflow. The higher the speed the greater the reverse airflow and the greater the turbulence created by the rotor which is felt as shake/shudder. I can almost imagine it behind my left shoulder, make sense?

Which brings me to a point I have not contemplated before... ANOTHER benefit of a gyro over other aircraft!! Helicopters are prone to retreating blade stall at high speed which will manifest itself in the tip (lift generating area) of the rotor. This stall will cause a sudden loss of lift in that sector of the retreating blades' rotation. Clearly the loss of lift will result in a sudden roll. Should the roll progress to the point that the controls hit the stops and not be corrected you will find yourself in a high speed dynamic rollover. Right? [Will spoil your day for sure] If you agree then you will also agree that this cannot happen in a gyro, even if you overspeed the rotor somehow. All that will happen is that the reverse airflow in the 'stalled' area of the blade will grow larger creating more drag. Until this interferes with the airflow over the lift generating tip it will have no effect on the lift vector.

Not sure if I'm off the mark but am keen to hear the views of more knowledgeable people. (And Brian)

[Coyote]

FO Gyro - hell bud your aerie is a bullet. My aerie has been taken up to 115 mph (vne) and as JR said nothing happened - but I have not personally been in the aircraft over 100mph. Now that we have satrted this discussion I will look tommorow at my MP also. At 80 mph my rotor rpm is 330 unless i am comong out of a steep turn then it increases to around 360 and then drops back. My understanding is that the rotor rpm on the MT is alot higher ??? any idea what your rpm is at cruise?

[t-bird]

29 inches one up and halve tank 105 mph in the Ela.
RPM just under 5000. Maybe a courser prop.
29 inches 2 up full tank hot day 90 mph

The QNH also have a big effect on the performance

Rotor RPM on Ela and Magni about 380 RPM in Gauteng at 7000 feet it increases to over 400 RPM

[FO Gyro]

The Germans are apparently very weight conscious, and they have done a good job in the MT-03 to get weight down, hence the performance figures.

Jetranger, in the MT-03, my rotor RPM 1 up is about 370 RPM, 2 up, it is about 400 RPM, and about 410 RPM with a heavy passenger. These numbers are slightly higher compared to my Magni Gyro that I owned previously.

Please forgive me if I am insulting your knowledge, but one's engine RPM has no direct link to your rotor RPM, although there are exceptions. If you fly at a very low indicated speed, with full power, the rotor RPM will drop. In this state, the rotor is less loaded, because the engine is assisting to keep the aircraft at a constant altitude. In other words, the rotor has to work less, because the engine is keeping it in the air. If you had an engine powerful enough, you could literally sit hanging on the prop, and the rotor RPM would drop to zero. This is not a good situation in gyro's. I have heard of a rule of thumb that said that one shouldn't let one's sustained rotor RPM drop by more than 10%. eg. if Rotor RPM is 350 in the cruise, don't let it get less than 350 - 35 = 315 RPM when flying at a very low airspeed with lots of power. Rather reduce the power a bit, and the rotor RPM will increase again.

Jetranger, I only get to use full turbo on a very short runway, otherwise there is not need to use 40" of manifold pressure. I never need it in flight. I normally take off with climb power (35" MP).

Attached is a photo of my gyro at 10 700feet. You can see the rotor RPM on the left of the photo at 370 RPM. I would imagine the rotor RPM would have increased slightly to about 380RPM if I accelerated to 90-95mph (my normal cruise speed), so I think I am correct in saying that rotor RPM does increase slightly with altitude, but not by much.

t-bird, the ELA figures you give are about the same as what I get on my machine. At the end of the day, the performance of any aircraft is directly proportion to its weight if using a similar wing profile.

[Gyronaut]

I will check next flight but I am sure my rotor rpm does not drop by as much as 10% when I go into a power-on hover. (320-32=288 - nada) Dont think I have ever seen it below 320. Logically it should drop yes but cant say that I have noticed a marked drop and I often pull the nose up into a hover with power on. (obviously not full power) Does reduce the rate of descent significantly.

[Coyote]

T-Bird - I flew this morning and was watching my manifold preasure. At 80mph (5000rpm) i was reading 29 and sometimes 30 inches. (generally stayed at 29)

[FO Gyro]

Also flew today on the Highveld. Generally flew at 28" which gave 95 mph. 29" felt a bit too fast today as the Highveld is slightly turbulent with the warm weather we are having. 29" gives over 100mph, around 105. For me 27" and 4900 RPM is comfortable at 90 mph.

[t-bird]

Hi Eagle1

If you where 2 up then the Sycamore is 10 mph slower than the Ela and Magni.
If one up 20 mph slower.

[Gyronaut]

must be 2-up unless he went solo without telling us. Also doubt that he will be taking note of airspeed, map, density altitude etc. to report back to us. If he's anything like me he'll be thinking of where the hell he is going to put this thing if the donkey dies. Something we never 'unlearn'.

Is that with or without cabin heat on Eagle1?

[Coyote]

Stefan Grove (110kgs plus instructor)) the owner of Sycamore flew my plane on Friday and was straight and level at 4700 rpm so it is not possible to compare unless all the conditions are exactly the same. The ELA is not faster it was just faster under the conditions that you tested. My aerie flies at 100mph but seems to be happy at 80 mph and as I am not trying to get down as soon as possible I am quite happy to fly where she is comfortable.

[Coyote]

I was chatting to Merik (303) and his comments were valid - a larger rotor has more drag (aerodynamic fact) but the secondary effects have to be calculated under the exact same conditions to accurately determine the true results. If he wanted to race gyros then he would go for the smallest possible rotor (less drag) but then the motor would be working far harder to generate enough lift.

Quite frankly I am not that obsessed with speed – flying these type of aircrafts is about the journey there and spending time in the air. If you are trying to beat everyone there then you have totally missed the point of flying.

[t-bird]

I am going to start a new topic – Gyro speed comparison

[Wako]

I fully agree with TBird who has done his homework well and present his case without emotion against all other that has either a vested interest or are busy with damage control on the marketing side.