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January 09, 2011

Dual Rotor Gyroplane

Dual Rotor Gyroplane/Gyrocopter/Autogyro - DGiPi

This is totally something new to me n yet i started my rc involvement with helis. we know autorotation landings for helis as an unpowered maneuver which practically used to end a flying session (for most of the pros/semi pros of course. but do we ever thought that autorotation can be use to create lift n used as wing for an airplane? well thats just what this vintage aircraft does. unpowered rotor as wings. so how it works?






here's to a better quality video (courtesy frm wanakaw - arca).



my interest in gyroplane started here as a challenge, there you'll find simple n brief introduction into gyros world: http://www.umranrc.com/forum/viewthread.php?thread_id=3124&rowstart=0

here's some links for further reading:

http://www.autogyro.com/

http://www.rcgroups.com/forums/showthread.php?t=614030&highlight=gyroplane

http://www.w-p.dds.nl/bookaut/

in this post i'll concentrate on my DGiPi developement.




you might ask why dual rotor? most of the aircraft is with a single rotor setup. well, from my reading thru all the faqs n beginner in gyros suggested that first, we should build a well know/ working model as our first gyro. second, i would be easier to handle a dual rotor setup for a beginner. so im a beginner in this, so i follow what others suggest. except, the first one.

as im used to build on what i already have, so the first rule seems to be broken. the best dual rotor setup which i've found on RCG, is TWIRL by Alfoot. its weight 250g. n most of my build will not be lower that 400g. so have to make some change in plans. i decide to used alfoots twirl as my reference. but i'll build mine as a stick gyro instead of al's 3mm depron all around. first need to read a lot. have to know what i'm into. how to make it fly as al's twirl but with more weight. i'm thinking of wing loading as my plane build. but found that in gyros, we are more interested in discloading instead. i would say it would be as wing loading in plane, but instead of wing area, we r calculating the rotor disc area. hmmm, just like helis. but i believe not many of us even bother what our helis disc load is.

Disc Loading :  http://www.autogyro.com/technic/f-1.htm

1 rotor = Weight/Area of rotor

Side by siden rotor = Total Weight/Total Area of rotor

To calculate disk loading:

Step 1 : know the weight in ounce (oz). times weight in grams with 0.0353 to get the weight in ounce.

Step 2 : know the rotor radius. basically its the length of ur rotor blade in inch (in).

Step 3 : know the total rotor area in square feet (sqft). need formula tu find an area of a circle - radius^2*PI . as our radius is in inch, so devide by 144. we'll get :

(radius^2*3.14)/144 = rotor area in sqft

well need to double this number for dual rotor setup as we'll have to saperate rotor area.

step 4 : calculate the disc load with this formula :

discloading (oz/sqft)= total weight (oz)/total rotor area (sqft)




n from here we can simple reverse engineer the formula to find the appropriate rotor size. but first, how this disc load relates to the gyro flying character?

as we know for wing loading, the smaller the number, we can make a shorter take offs n slower flight. it seems to be true for gyros too. the suggested number would be below 5oz/sqft. below 3 n it will be a floater.

will continued ...