VNE ????

[asra]

I am very courious as to how I could workout my gyro's VNE ?Is it calculated, or test flown, or measured by stresses placed on the airframe, and components?Regards Sam.

[NiqueNaque]

I have no idea, so this will be interesting...

[asra]

Somewhere amongst all my paperwork "junk" I have it written somewhere. Goes something along the lines of flying it faster and faster until vibrations/control threatens the machines safety, and then back off a bit. Also seem to recall that it was recommended to get a very experienced pilot to do it. Seems to me that if he was experienced he wouldn't wanna do it. If you're real passionate about the subject, I can dig it out, but it's not much different (in essence) to what I said.

[Ken Watson]

I think it is a more personal decision based on risk. I set mine at 60knts because Robbie Glenn said if I dont exceed this I should never get in trouble. Sounds reasonable to me. Ken

[asra]

The actual VNE of the individual gyro is most likely an arbituary figure at best. Like Ken and Fred say, if the gyro has sufficient power, it will push to a speed where the pilot himself will start to feel uncomfortable with vibration or the way it begins to handle and that would be best to be regarded at its point of VNE.Pete

[asra]

All seems to easy, and I thought it might be a little more complex than that.When you compare a gyro to a FW aircraft, our machines become alot more complicated as airspeed is increased and the machine is pushed to its extreems.The rotor blade is what makes our machines more complex, as its mechanical simplicity, is quite complex in its workings.At max speeds our disc angle is quite shallow, and the retreeting blade has most of its surface area stalled. Couple this with possible pitch stability issues, and it can be quite scarry to even think about flying a gyro in this way.A simple formula would be safer.Regards Sam.

[asra]

[asra]

G'Day PeteTo clear it up for our members, the flip over you refer to is a roll and not a tumble.But the tumble can arise at minimal disc angles flying at high speeds, and combining PIO's, or turbullent conditions. I have had my machine flying straight and level at full noise 70 kt's, and even though it flew with no change in attitude, I was still very nerves and backed off after about a minute.I'm quite shure it would fly even faster if I lowerd the nose, butwill leave that to the test pilots. I suppose my consience got the better of me.Regards Sam.

[Brian]

Sam, the position of the stick in relation to the speed is important as you may find that the faster you go, the more you need to push the stick forward. The US post I read, the guys there reckoned they had 110 or 120 knots and full forward stick which im my humble opinion, extremely dangerous!!!I have had my old girl to 80 knots GPS and backed off there as it wasnt comfortable [ie to my normal cruise of 50 knots]plus the fuel flow meter wasnt saying nice things Always better to fly at a speed where you are comfortable at !! Remember that rough air isnt the place to try to go fast !!Brian

[asra]

There are old pilots and there are bold pilots...but there are no old bold pilots...Backing off just shows you are catching up to me in years Sam.Pete

[asra]

Hi BrianI agree with the stick movement, but there is, and can be a huge difference between airspeed (ASI) and ground speed (GPS).I have had my machine flying at 98 knots ground speed, at 2000 ft AGL, and couldnt get the extra 2 without lowering the nose.At that speed, my ASI was between 65 and 70 kt's.Airspeed = safetyGround speed = DangerRegards Sam.

[asra]

Hi guys,In 'helicopter' talk the VNE is governed by Main Rotor RPM because it is a set figure. The negative effects of the retreating blade 'flying' slower than the advancing blade is well documented and is called 'Retreating Blade Stall(RBS). Lower speed, lower induced airflow, higher angle of attack and reversed flow over the inboard section of rotor.... RBS. You have probably noticed that in most helicopters the VNE is around 125 to 130 kts due to the rotational speed of the blades... they cannot physically go any faster due to RBS.Because a gyro's RRPM is governed by airspeed if you have the power to go like the clappers then the arbitrary speed of RBS onset is continually being increased. You could technically fly much faster than a helicopter for the same rotor diameter. Thats of course if your blades don't fly off or you get blade flap (air is compressed at high speed, blades don't fly like they normally do)Decreasing rotor diameter or increasing RRPM will improve the VNE capabilities of a rotorcraft.Just remember though, a large christmas beatle travelling at over 200 km/hr will probably hurt.Paul

[NiqueNaque]

I remember a post made some time ago where the blade speed is limited by the number of blades that you have on your gyro..Time to have a dig in the archives from about 5 months ~ 8 months ago.

[Brian]

There certainly can be a big diference between ground speed and indicated airspeed. I would suggest that most IAS read faster than actual so thats where a GPS run in TWO directions are needed to get a true speed. You were certainly pushing hard there Sam and what a pity you couldnt get the 2 extra knots I have seen 100 knots a couple of times but had a strong tailwind.Brian