Disc Loading....what is too low?

[Brian]

so mitch your going up 30% to recomended in the book. i can"t say i blame you . i"m looking at the same. soo.. what is too much ?sam i"ve seen your photos of hang and c of g test before. i just can"t remember how the c of g. is effected by rotor length. can you tell me where your post is again ?My version of too big of rotors is something like this, gyro feels flighty in thermals /wirlys etc and when pushed hard from S&L to hard turn, dont respond quickly. If you have a rotor tacho, you should be around 350 revs and no lower than 300. Thats my personal opinion. I like a low disc loading as I like to be comfortable when fully loaded on a hot day and still have good performance to be able to work close to the ground with safety.Also, TA"s should have a rough idea and if all else fails, call Ross Symes.

[Greg Mitchell]

Tony,I believe the disc loading kept with certain parameters is a good thing.Disc loading is a subjective thing.I liked my little floaty Butterfly at 1.34 psf (average/half full).I really like the Monarch at 1.44 psf but at 1.59 psf the blades are spinning well into the 380"s with a fuel load of fuel and a bit of "pace up". I have been told that once you get up over 365 rrpm approx, then the drag on the blade becomes problematic. Therefore, the tips speeds are also as important a set of numbers as the rotor rpm.Tony, I am very much a newbie with approx 110 hrs and just this last few months have looked into the disc loading issue as a result of wanting to add more weight to the gyro. I figured I needed to look at the numbers to see what I could do without going another bigger engine. :I am now quoting some figures from my training diary, pre-solo days.500 lb AUW gyro with

[Greg Mitchell]

G"Day Chopper,Good post. Mitch

[Brian]

G"Day Chopper,Good post. Mitch Hi Mitch, I"m not much in the technical department so I just say what feels comfortable to me flying. I have learnt a lot from Rob thankfully plus having a rotor tacho gives an actual to what the blades are doing.

[tonydenton]

mitch, rather than me looking back through books could you put up the disc looking formula please?

[Greg Mitchell]

Tony,Disc Loading is derived by dividing the AUW of the Gyro by the Disc Area...this will give the upper limit.Then do it again empty of fuel. There"s your ultimate lower limit.Pie (3.1416) X Radius Squared (Feet) = Disc Area (sq/ft)AUW (lbs) / Disc Area = Disc Loading (lbs/sq/ft)21 fT Blades21 divided by 2 = 10.5 radius ftTherefore, radius squared is 10.5 X 10.5 = 110.25 sq ft3.1416 X 110.25 = 346.36 sq ft500 lb AUW Gyro Divided By 346.36 = 1.44 lbs sq ftCheers,Mitch

[tonydenton]

thanks mitch, it makes it clearer but with all the maths there are still some grey areas . if you had one brand of rotors and only changed the brand you could increase the rotor area only by some 15% [ not disc area ]. the disc area doesn"t factor in the chord of the rotors.so the disc area/load

[Greg Mitchell]

Tony,"if it flys well for what i want and how i fly then it doesn"t really mater."

[Brian]

"if it flys well for what i want and how i fly then it doesn"t really mater."

[birdy]

[i]"if it flys well for what i want and how i fly then it doesn"t really mater."

[Greg Mitchell]

If we could, I really like to focus on the original question of "what is to low?"There are a lot of experienced gyroplane pilots here as a newbie pilot, given recent events and my intended upgrades I would appreciate a bottom end figure.Fact is most likely it"s the Musterers who fly some of the lowest disc loadings and I feel there must be a number we can assign to that bottom end. I know Birdy, Chopper and others have an intuitive feel and understanding of all of this, I however do not.Perhaps we could identify the lower end disc loading figure to be when the rotor rpm drops below a certain number. A number that might worry a seasoned Musterer.The weekend flyers such as myself can identify more readily with rotor rpm numbers and not everyone cares about, the who, why, what, when, where and how of the blades. So I apolagise for being a pain in the butt with it.Mitch.

[tonydenton]

mitch and dave , ok i admit not the clearest statement to make . i might be able to clear it up. firstly i should apoligse to brian for putting his name in with my choice of words. mitch now you mention you do have stats including chord[ which is all i was tryind to show the difference that doesnt show up on your disc loading math] if you have all the maths for it including chord why dont you press the equals button on the calulator and that will be your real answer. if your chasing lower disc loading than that,then your only doing what i have done. started off with a known and made some changes to suit me only. i dont lend it out or let my gyro be flown by a t/a that isnt the correct size [my size]eg; waddles would crash, his arms and legs are to short. no offence al.

[Greg Mitchell]

Good Morning Tony,My Fault Tony. I should have stated that the math included chord width variations etc.Fly Safe and enjoy the flying.Cheers,Mitch

[Greg Mitchell]

Tony,Do you have the Beaty Excel spreadsheet for disc and blade loadings etc?It is a wonderfull tool for what you are doing now with your research.Cheers,Mitch.

[birdy]

dave , i learnt my solo in a rosco machine and did about 25hrs, yes they fly well.so a couple of t/a said what to do[changes] to suit me when building mine. i ended up with a machine that suits me for how i fly.Tony, the first time i raced in the Fink Desert race, i rode an XR600.Wen i finished [ still alive] i thought " wot a magic machine, nuthn beets an XR600."Next year i rode a KTM600.An hour quicker and no stepoffs, and i thought, " geez, them XRs are heavy pigs o bikes."Same goes for any machine, horse, woman,................. .Mitch, your lookn for a definate, there isnt one.Too many vairiables.There is only a "happy allrounder", and that depends on more vairiables.The min size rotor is mainly dependant on available thrust. [ prop]The max size rotor is usualy dependant on function.I cant think of anythn besides engineering that would stop you putn 60" blades on ya butterfly. Itd still fly, but control would be so slow itd be getn dangerously overrotored for even the best.