Want to build RC Gyro, please help with basic specks

[asra]

Well me mate Jeff B has got me interested in Gyros.Knowing absolutely nothing about them I thought it would be a good idea to build a decent sized RC gyro with roughly 600mm blades from a RC heli.So know what I would like to know is some basic specks.Hang angles n stuff, blade pitch n stuff airframe dimensions and anything yas thing relevent.This should be fun !

[Greg Mitchell]

Excellent!Revmax you might like to check out the yank forum, there have been a few RC gyro threads there.www.rotaryforum.comGood luck.Mitch

[asra]

Thanks Mitch.Lots of stuff on that forum, so much that I got lost.Are there plans available that I may be able to scale down.

[Greg Mitchell]

Carl,You can down load a copy of Ralph Taggart"s Gyrobee plans off the internet. It is a pusher gyro, like most of us fly.Mitch.

[asra]

Thanks Mitch .I found them. http://taggart.glg.msu.edu/ftproot/gbeer50.pdfI wonder is there a 3 view drawing that could give some basic specks.

[Greg Mitchell]

Dont know, try Jukka Tervamaki (sp?) his site usually has some good graphics and plenty of insight.Mitch

[jeff b]

Have fun mate. Let me know how you get on organising that TIF in the full size version

[asra]

All sorted Jeff. Australia day at Palmers Island.I am just going to start making a RC Gyro and see how it pans out and have started with some surpluss bits from T600. will be using 6S 5000mA LiPo, have some ESC"s and 42-60 600KV motor for propulsion, 35-30 1050 kv to pre spool the head and was just going to use some 25mm box section for the frame.What pitch should I run on the blades. (have some semi symetricals)What angles of insidence should the head run between.What cyclic (left right) should be run

[asra]

Good old brushless motors. you could do away with the pre rotator as a quick spin by hand would do the job. Blade pitch = try 1.5 degreesSet head at 9 degrees to the horizontal / Keel.Head movement should be 9 degrees forward, back, left and right. In other words total movement in roll would equal 18 degrees. Total movement in pitch would equal 18 degrees. Hang machine at 9 degrees (if CLT) Check this out it may help if my explainations dont.

[asra]

Thanks Sam. Starting to understand the lingo. I have made the head with privision for pre rotor and just worked out a much lighter set up than my original idea but will leave it off for now.

[asra]

OK The ball is rolling.As pictured so far.Just some alloy box section, alloy angle and alloy sheet.Electric motor, motor mount.The UC us from a RC Trainer.Head and maingear is from a T600. Jeff should find that amusing.a few parts on order and a few parts to make.

[jeff b]

Looks good so far Carl. Yes it brings back some RC heli memories. Nice work

[MechFx]

google rc autogyro plans revealed this .....Beginner Autogyro/Gyrocopter/Gyroplane Questions and AnswersOk, here"s a starting point for a sticky on Autogyros.If I left someone out, I"m sorry, I did this very quickly.My proposal is that we all edit on this for a few days andcome up with something that we can live with so wedon"t have to answer the same questions over and over.So what I ask is that if there are corrections, let me know and Iwill edit the original and re-post until we get something we can live with.I"d like to not drag this out forever so can we get it done in 1 week,then we can figure out how to make it a sticky.....mickGyrocopter Questions1) What is a gyrocopter,autogyro,Autogiro,gyroplane?A rotary winged aircraft that derives lift from a non poweredrotor(s) and is pulled (or pushed) forward by a conventional engine/propellor.The names mean the same thing but are various marketing/registerednames for brand name aircraft. (all Kleenex is tissue, but not alltissue is Kleenex....)2) Are they hard to fly?Somewhere between an advanced 4 channel airplane and a helicopter.Typically they are considered not beginner models.3) Are they hard to design? Don"t I just put some helicopter bladeson top of my airplane?YES and NO, respectively. Most heli blades are the wrong airfoiland the wrong aspect ratio for gyrocopter blades. http://www.aerobalsa.com is a good source for gyrocopter blades.4) I have an old fuselage I want to convert to an autogyro, whatdo you suggest?Not to. Build a gyro from plans or a kit first to learn the differentflight characteristics. Then set out to design your own.5) What are the controls?Several types:Fixed rotor with rudder and elevator control.This is very difficult with a single rotor, very easy with a dual (side by side) rotor.A tilting spindle cyclic control rotor ("direct control") that tilts for aileron and used rudder and elevator.A tilting spindle cyclic control rotor ("direct control") that tilts for aileron and elevator with a regular rudder.A rotor that uses "helicopter" type controls like a swashplate.6) What kind of power do I need?Generally thrust needs to be greater than weight.7) What kind of "wing" loading?The disk loading is the weight of the model divided bythe area of the whole rotor disk. ~2-3 Ounces/sq foot fortwo bladed systems, ~3-4 ounces per sq for 3 or 4 bladed systems.8) Are there kits? Plans?YesThe Slow-G twin http://www.slow-g.com/The PtGyro family : http://www.flyingbalsa.comG3PO,BEGi and GT17: http://www.mickeynowell.comSeveral from Arizona Autogyro : http://www.autogyro-rc.com/The DAG01 http://home.att.net/~imsofaman/dave_....htmWhopperthe plans:http://www.vth.de/Modellbau/FMT/dow....oads.aspdirect link to part1 and 2 of the plan:http://www.vth.de/Modellbau/FMT/dow....er%202.pdflink to the thread at rcgroups:http://www.rcgroups.com/forums/showt...p?t=487131link to german thread incl. comments of creator:http://www.rclineforum.de/forum/thr....micromumhere"s the link to the latest version of the Micromum plans:http://www.rcgroups.com/forums/show....ostcount=69and this one is for the Minimum:http://www.rcgroups.com/forums/showt...?t=543196Twirl : http://www.rcgroups.com/forums/showp...3&postcount=639) Where is more information?Almost any question you might ask has already been answeredat one of these places. Use the search feature to look for specific words like "collective pitch" or"direct control" or "advancing blade" and you willfind many questions and answers.http://www.autogyro.com/http://www.r...ay.php?f=11310) Which ones are the easiest to get to fly?The Slow-G, Twirl, Whopper, and any of the plans for the dual rotor designs like the Spin Doctor from flying models.11) I"ve designed a scale Bensen/Brock/Little Nellie andit won"t fly. What"s wrong?Gyrocopters don"t scale well, namely the mast angle has tochange, the blade pitch has to be negative rather thanpositive and the control systems have to change toallow for the increased control response from the rotorwhen they are scaled down to model size.12) I got a from a garage sale, should I try to fly it?Probably not. Build a modern design, learn to fly it, thendecide if you should attempt the _ you got from the sale.13) I really want to build a scale _, how should I start?Build a known design first, learn to fly it, then re-evaluate.Gyrocopters really demand a different (not particularly harder,just different) skill level, especiallywith regard to the left transmitter stick (throttle and rudder).Trying to learn this on an unknown new aircraft is challenging.14) What is the best way to get started?Build a kit or a known good design appropriate for your skilllevel. If you are an beginner/new airplane pilot try a twin rotor first, Twirl, Slow-G or Whopper.If you have beyond beginner skills with airplanes the PT Gyrosare great. If you have advanced skill and/or have flown helicoptersG3PO and BEGi are good performers. None of these models are appropriatefor rank beginners to R/C. The models from Arizona are more scale oriented if that is your desire.15) Are there some gyrocopter fly-ins?YesGenerally in March at Spring Hill Florida,September in Muncie Indiania andnew this year Lakeland Florida in ??InterEx http://www.inter-ex.com/ (Thanks to Stephan B)16) When I try to take off and I pull up elevator my model just rolls over on it"s back and does the funky chicken, what"s wrong?Your rotor has not reached full "autorotation". This is the conditionwhere the rotor is not just windmilling slowly but turning at a very high rate. In this condition the centrifigal forces are high enoughfor the rotor to be stable and it is producing enough lift to flyand keep it self spinning. It is important to get the rotor intoautorotation before flying and allow the model to fly on its ownwithout up elevator.17) What are the different rotor configurations like?Single uncontrolled rotor : Very difficult to get to fly well. Requirescareful design to get trimmed. Controlled by rudder/elevator and throttle (RET),or in the smallest case throttle and rudder only. Has the least manuverability.Dual uncontrolled rotor : Easiest to construct and get flying. Controlled byRET. Stable and manuverable, capable of loops and rolls. Poor control at low airspeed since the rotor is capable of making lift at almost no airspeed butthe control surfaces lose effectiveness. No control at all in vertical descent.Single Tilting Spindle Rotor : Requires a little more attention in building.Much more rotor control especially at low airspeed. More sensitive controls andcapable of aerobatics (loops, rolls, stall turns, etc.) Good control in vertical descents. Most scale appearing rotor head. Easiest to hand fabricate.The rotor is slightly unstable in model size so these models have horizontalstabs to make the aircraft stable. Need heavy duty (metal gear) servos.Single "Heli" Rotor : More complicated head design, requires attentionto detail in assembly of the rotor head. Very stable rotor somodel doesn"t need horizontal stab. Very manuverable, especially at lowairspeeds. No special servo requirements. Some parts must be commerciallypurchased. Hybrids : There are combination designs, such as a tilting spindle headwith a flybar. These possess some of the qualities of both types of models.18) Why aren"t there any scale "Bensen" type gyrocopters?The bensen style rotor head becomes unstable in model form, mainly becauseit has to spin much faster and has less mass. The controls get too sensitivefor a human to fly, much like an airplane with such a high roll rate that you can"t keep it level. The same problem happens with model helicoptersand this is the reason the model helicopters have flybars, to tame thehigh control rates that don"t exist in full sized aircraft. This principlecan be illustrate

d by trying to balance a broom in the palm of your handand then trying to balance a 1/10 scale broom in your hand. 19) Why do model rotor blades have to be set to negative incidence while full sized gyrocopters have positive incidence?The lift to drag ratio (L/D) of small airfoils is much worse than bigger airfoils due to "Reynolds Number" effects. Autorotation is only achieved at close to the best L/D for the airfoil which is much lower (at negative incidence relative to the rotor shaft) angles than full sized. The rotor blade still has a positiveangle of attack with respect to the air since the whole rotor is tilted back.This also explains the model heli blades are poorer performers than purposebuilt gyrocopter blades with high L/D ratios.20) Why do models have a greater mast angle than full sized?Same problem as #19, little airfoils are less efficient and need a differentangle of attack.21) What is the advancing blade? Asymmetric Lift?This is the condition where the forward going blade is gettingmore wind than the one going backwards causing a difference (asymmetry)in lift. If you do nothing about it the advancing blade will rise up in front (due to gyroscopic precession of the rotor) trying to flip the aircraft up vertically. To fly successfullyyou have to apply cyclic pitch so the advancing blade has less angle ofattack than the retreating blade. The cyclic pitch can be either "flapping" with a flapping hinge, or "feathering" with a feathering hinge. Un-controlledrotors use flapping hinges, or in the case of dual rotors let the asymmetric liftcancel each other out. Controlled rotors, tilting spindle or swashplates, usefeathering to cancel asymmetric lift. This is a slight amount of down elevatorin either case. This is an advanced topic with lots more to read in the referencesabove.22) Where should the CG be? What is the "hang angle"?The CG should be directly below the center of the rotor when it isplaced horizontally, or slightly ahead of that with models that havea horizontal stab. This gave rise to the concept of "hang angle", method that describes how far down the model hangs when hung fromthe rotor. Generally the hang angle is roughly the mast rake angle,which results in the CG being centered under the center of the rotor.23) What"s the difference between a puller or pusher layout?The puller results in a shorter (height) model that has better ground handling.The pusher layout is harder in model form because model propellers are longer relative to the model size than full size. This makes gettingthe overall proportions more difficult and getting the thrust angles more challenging. The pusher layout is shorter in length which worsens the stability, this makes the more sensitive model rotors even moresensitive. Most models, expecially for beginners, are puller layout.24) Can you hand launch?Yes. Most models hand launch well, especially with a slight breeze.25) How about high winds? Crosswinds?High winds are ok as long as they aren"t higher than the max airspeedwhich is ususally pretty low. Downwind turns and downwind passestend to get the gyro really moving and need attention to the throttle.Crosswinds are the worst possible condition for gyrocopters. Rise of Ground takeoffs are possible if you can line up roughly (10-20 degrees)with the wind. Otherwise it"s best to hand launch directly in the wind.Landings with crosswinds are usually not a problem, just land into the windbecause you have no rollout, so you can land across most runways easily.26) Engine out situations?Tilting spindle and swashplate controlled models have full control. You havea limited glide angle (about 1:1, or 45 degrees down), but you can flareto a zero rollout touchdown. Elevator controlled models are usually less controllable with power off and tend to be built light so theycan just descend vertically to a "plop" landing. A little forward speed reduces the sink rate.27) Touch and goes?Easily.28) Does collective pitch help?Not much. It has been done and doesn"t add much to the overallflyability, although it does reduce the spin up time. The addedcomplexity is for advanced modellers.29) What about pre-rotation?Most models use the "hand flip" method. Some models haveused a drill or other motor to spin up. There are no modelsthat have built in pre-rotation, but I"m working on it.

[asra]

Wow !Thanks Art.

[asra]

I have ditched the alloy fin and added G10 Fins and rudder.Added some wheels2 x ESC"s one for main motor and one for pre rotor.The pre rotor motor is an EMAX 950kV with an old Align 3.8:1 planetry gearbox, with a 10T pinion driving the T600 maingear, I estimate the pre spool head speed to around 300RPM.The ESC for the pre spool is set to "Super soft" start so I I have to do is flick a switch on the TX and it will wind up, taking about 6 seconds to reach full RPM.Next the servos will be mounted, bopefully tonight. Some InoLab 650MG should do the job.Putting a model together with pop rivets is so much fun