Soooo.... you want to try an Autogyro?

Please note:   This file is occasionally being updated, particularly in regard to the suggested beginning models, etc.  Much has changed/learned since originally written several years ago...

The following comments are the expression of GyroNUT modeler,  Jim Baxter, and while they do not necessarily reflect the opinion of every gyromodeler,    it is an accumulation of suggestions learned from working closely several years with many of the most active and knowledgeable R/C Autogyro modelers in the U.S.,  the U.K.,  France,  and Spain..... and is placed here in hopes that they will be an aid to the beginner...

If you feel you want to begin by scratching/designing a scale, semi-scale, or such... PLEASE DON'T!    Scale would be very difficult if not impossible until you have gained a strong knowledge of basic autogyro building and flying...   If you insist on going that direction at the very beginning, we can almost guarantee you severe problems...   and we are not going to be able to help you.    Begin first with the small and simple... avoid the frustrations of many, many, modelers who wanted to start at the top, only to quickly end up at the bottom.   We are constantly plagued with cries for help from modelers who insist they want to begin with a scale of a Bensen, as an example...   Unless you are a graduate aerodynamics student with lots of modeling experience, don`t even consider it.   Without some experience that can be very difficult to say the least.  Occasionally we are asked for help when someone tries to convert something to an Autogyro,  as an initial project.     Please don't begin with a the idea of converting your favorite model airplane into an Autogyro, and then ask for assistance when the model won't fly.    There is just nothing we can help in that situation except suggest you scrap the model and begin with a proven design... FIRST!

There`s more to it than just tossing a model aircraft together and go fly.   Let`s ask a few questions before we get down to the nitty gritty:

** Do you have some R/C experience?    By this we mean something beyond the trainer 40 stage.   Autogyros are just a tad more difficult than model airplanes,  but perhaps less difficult than helicopters.    If you are an experienced model helicopter flyer,  you should have little or no problem with an Autogyro,  but even a modeler with some airplane experience can/will experience some re-orientation and learning requirement.   If you have no (zero) R/C experience,  then an Autogyro is not the thing to begin with.    I would suggest you find a good instructor,  learn the basics of aircraft flying,  then (with the instructors assistance) go for an Autogyro.    Let me say this.... everyone I know of that has flown a model Autogyro for the first time,  finds the experience exceptionally satisfying and rewarding.... well worth the time and effort.

** Do you have a place to fly one?    That may sound like a silly question,  however you need to understand another requirement for flying an Autogyro.     The nature of it`s aerodynamic`s dictates that it must launch into the breeze.    If you build a small one that can be hand-launched into the breeze,  that is not much of a problem, since you only need a spot big enough to plop it down with very short landing roll.    However,  sooner or later you will have a model that needs a runway,  and wind direction becomes a very real problem.    You should not or I should say.... cannot... pull an Autogyro off the ground to clear the end of the field satisfactorily.   So, how much runway will you need?    Well, many factors need to be considered such as the altitude of your flying area,  strength of the breeze,  etc.,  but let`s just use an aproximate minimum figure of 300` into the breeze as a general guide for most model autogyros.   Landing space is not as much of a problem,  since with practice you can complete near zero ground roll touchdowns.

**Do you understand why and how an Autogyro flys?    If your answers is no,  then you need to browse the information posted here,  and the other pages of info we have posted to familiarize yourself with the idiosyncracies of model Autogyros.    Once you have a general idea of their flight characteristics,  then you will find understanding what they do and why they do it quite fascinating,  and learning to handle one will come much faster and far less frustrating.    We are speaking here of primarily true autogyros, those not requiring the assisstance of any, or at the most a short stubby winglet...  If you find all this just a bunch of "B. S."  (breezy speculation?),  then let me ask you... how many Autogyro modelers do you know personally?   Why aren`t there more of us?   The answer is that they are quite unique ,  can be difficult,  and the "average" modeler is just not interested in the challenge and/or work.

If you like a challenge, and want something unusual and unique,     Go for an Autogyro !

If you have read this far,  and are still interested,  then let me outline a few basic rules I think you need to know and follow:

I suspect not all Autogyro modelers will fully agree with everything I propose,   however my comments are pointed at the pure beginner with the hope that this will help you "get airborne" with a minimum of frustration and damage to your ego and wallet.

Begin small and simple!    First time autogyro modelers frequently express an interest in building and flying a scale model of one of the original classic autogyros of Juan de la Cierva,  as an initial project.   Even if you are a very experience modeler,  with a high degree of flying skill,  I still would recommend you begin with a simple,  small model.    Once you have mastered this,  then enjoy the world of scale autogyros,  or other challenging advanced designs incorporating servo controlled rotors,  etc.  Note: Since this article was first written back in 1996, a number sport scale model plans have surfaced, along with numerous non-scale model plans, well suited for the modeler with a little R/C experience to bulid and enjoy.   See our  plan page for further information all these model plans.   It is difficult to successfully convert a favorite model airplane to a model autogyro, even with some gyro experience, so that is certainly not recommend as a way to get started.   In addition, the power requirement for a a gyro is greater than the airplane.

There are a few plans,  and even fewer kits available.    Check out our  Plans page and "Autogyro  Co.   of  Arizona" for more information that regard.    I would suggest starting with something like the the GYRACE first (not a really true gyro, but it`s close enough to begin to get the idea),  then go on to the WHISTLER after that.   Both the Gyrace and the Whistler use winglets (short wings) to support the rotor, and are powered by a strong .25 up to a weak .45 engine.

The Whistler is a good model, formerly available in kit form, but now only in plans...   I would only suggest the Whistler for someone with a little experience, particularly since it requires the machining of a few aluminum parts.   The FALCON GYRO conversion to the venerable Falcon 40 model aircraft,  is a co-axial model and can be rather difficult for would be first timer, so it`s not recommended for the inexperienced.    The FA-61 would be an excellent beginner project.  Plans for Skip Ruff`s excellent model are now available from Bill Northrup Plan Service (see our plan page)    The FA-61 needs a strong .40 or any good .45 -.46.   The reason for different engine requirements on various autogyros,  in my opinion,  is due primarily to the amount of drag that different models present.  Drag is an important item of consideration with an autogyro.

The basic autogyro  (unlike the helicopter, or models using heli parts)  does not have a rotor blade control such as flybar cyclic control,  therefore can suffer from a roll into the retreating blade if not built/rigged/setup correctly.    So,  with this in mind,  I feel a dual rotor  (spread laterally,  such as on the tips of a winglet or booms)  provides you with significant lateral roll stability that the single rotor model  (Whistler, etc.)   may give you problems with.   

The basic GYRACE,  as per the plans,  is ok,  however I found that some modifications can turn a fair model into an excelllent one.    If you elect to follow my modification suggestions,  I think you will note a significant increase in slow speed performance,  such as during takeoff,  hovering into a breeze,    You may want to read my suggestions for Gyrace improvements .

Begin with a flat bottomed,  "Clark Y"  or "Clark W" airfoil shaped, rotor blade.    Flat "paddle" blades such as on the original Gyrace,  are relatively inefficient and not worth your time.   If you are not familiar with the Clark Y... simple take a good look at the Piper Cub aircraft airfoil.   The airfoil used on the original Whistler,  by John Kallend,  has a nearly perfect Clark Y blade airfoil.   I have,  along with many of the other gyro modelers have found that trimming / sanding the bottom of the Clark Y  (making it "flatter" on the bottom),  provides an excellent lifting rotor that also spins up quickly for launch.    It appears there are far more excellent rotor systems utilizing this type airfoil than any other.    Since originally completing this page I have completed a rough drawing of the airfoil I am using, for you to gander at.

Build your model with a  CG (center of gravity)  slightly forward of the rotor shaft center line.    This can be checked by holding your model by the rotor hub and noting what we call the "hang angle".    This is a negative  (nose down)  angle assumed by the model when held by the rotor center (shaft).    The degree of this "hang angle" depends on your particular models aerodynamics,  but generally is in the neighbor hood of minus 2 to perhaps minus 10 or more degrees.   Personally,  I feel it is relative to the size of the rotor and amount of drag presented by the rotor.    I find that models with a large and / or vertically raised rotor  (causing high drag)  will require more down hang angle.    As an example,  my Gyrace, with it`s low  (vertical)  rotors,  and low drag profile,  has a hang angle of only a few degrees.    A co-axial rotor model,  with it`s high vertical,  high drag rotors,  seems to want a large hang angle of perhaps 10 or more degrees.    All models differ some,  so the exact hang depends on your particular model,  and requires a bit of experimentation.  Note: Hang angle is indicative of CG location... the more the nose down hang, the further forward the CG.

If you have read the forum comment notes I have posted,  you will find Ralph Kalb explaining that,  for one thing,  this nose down "hang angle" is necessary to enable your model to properly begin and maintain an autorotating "glide" following a possible engine failure.

Begin with a tail dragging model,  rather than a tri-gear model,  if at all possible.    This is particularly important for flying off grass runways.    First,  the tail low / high nose high attitude assists tremendously in obtaining sufficient rotor speed for takeoff.    Second,  should you abort the takeoff with a tri-gear model,  the chance of a high speed "ground loop" is high... with significant rotor blade damage resulting.    Consider this:  with the drag / weight of the rotor being high,  vertically,  momentum can / will push the model over nose first,  and to the side when the nose wheel "digs in".    The Falcon Gyro can be easily converted,  during construction, to a tail dragger.   That modification alone,  contributed significantly to my version of this model acquiring 200 flights before being retired. Speaking of rotor blade damage,  prepare yourself for this frustration,  especially at the beginning.    It WILL happen and you will find yourself making new ones frequently until you have solved the mysteries of your model and / or your ability to handle these models.    Charles ("Jo Jo") Chaulet  of Antony,   France)  the fellow who has been fooling with autogyros for over a quarter century,  says he can`t even imagine how many blades he has made in all those years.   Jo Jo is the only autogyro model builder to have one of his models (a copy of one of Cierva`s first machines) on display in the "Museo Del Aire" (Spanish Aviation Museum)

You will need to eventually learn many of the "angles and dangles" as I call them,  in regard to autogyro aerodynamic rigging.    A web page listing of most of those   terms and their meaning has now been posted.    Keeping such things as blade incidence,  mast angle,  downthrust,  cone angle,  etc.,  within certain limits will aid significantly to the immediate success of your model.    Rotor types such as Teeter Bar,  Flapping,  Co-Axial,  Dual  (spread),  will be some things you will want /need to learn about. Check the Technical section of these pages and the posted "Forum Notes" for details on such items.

Flying an Autogyro can be an exceptionally exhilarating experience... the thrill and excitement of your first "trip around the pattern" is wonderful to say the least. There is just something unique about the sight and sound of the rotor (s)  that will hook you to this small segment of modeling.     But let me make one thing clear... you need at least a slight breeze to normally fly an autogyro.   To fly one in zero wind will require a good pre-rotation of the rotor and probably a long T/O roll.    If you hand launch in zero wind,   you`ll find yourself jogging like mad...  because you, yourself will have to make up for the wind.   Then if / when safely airborne in a zero wind condition the model must maintain sufficient forward speed to maintain lift.   Suggestion:  Don`t fly without at least a light breeze.     Takeoffs need to be completed at a slow pace.    Give the rotors a pre-spin with the model pointed into the breeze,  and increase the throttle at a slow steady rate during the roll.    Rapidly increasing the throttle may cause the model to launch straight up,  with a resulting rapid loss of control.   Should this happen, immediately reduce power.    A neat way to launch from the ground,  maintaining slow throttle use,  and remain within a decent orientation distance,  is to stand at mid-field so as to have the model pass by you on the roll.   This procedure is excellent for the initial testing of a new model,  when you you are never sure of just how it will react on the very first flight.    You should also check out the  Fying instructional page  in this technical section.

You will find it is important to color the model in a pattern that you,  personally,  find highly visible. Picture trying to fly a model airplane without a wing..!    That`s close to what an autogyro looks like in flight. Determining whether it is simply "coming or going" can pose a problem,  and when it is abeam  (sideways)  to you,  you need a way to recognize a turn towards or away from you.   I find that I have tocover the tops of the rotor blades in a highly visible, contrasting color to the bottom of the blades.   Then I constantly try keep the top of the rotor in sight... then I know the model is at least banking towards me.   A good procedure is to always turn into the wind, and towards yourself...  whenever possible. The one thing you do not want to do is allow the model to drift away from you, as it will rapidly become difficult to orientate on,  and you may face a deliberate autorotation landing situation.    When you encounter an emergency situation such as loss of orientation,  engine failure,  or just a plain loss of control,  the corrective procedure is generally always:   (1)  Reduce power to idle immediately.  (2)  Release the controls.  (3) Wait & watch.    Providing you have sufficient altitude,  the model will likely  (hopefully)  attain a level attitude, and begin an autorotational descent.   The rate of descent will depend on your particular model,  however it will probably resemble a "slow rock" coming straight down.   While the rate of descent may break the landing gear and propellor,  it should basically survive the event in reasonable condition.   Altitude permitting,  you may be able to lower the nose and re-gain some directional control.    If so,  and you have good orientation,  along with an operating engine,  slowly increase the power & bring the model home to a good landing.    If you do not have good orientation, cut the throttle to OFF,  let it land itself,  take a bearing on it`s location,  and prepare for a hike.  

Hand launch  (small)  models:  This is an important consideration for a safe,  comfortable launch,  since you are standing close to them at the time of release,  with orientation just not being a problem.    If your model is small enough to hold along the bottom,  directly below the rotor,  face into the breeze.    With the model pointing up at about a 45 degree angle,  give the rotor a spin,  allow it to accelerate while walking into the breeze and increasing the throttle to a safe flying power  (perhaps 3/4 open).  When the rotor really accelerates,  lower the nose to just slightly  (10 degrees)  above level and "push" it lightly up and into the air.    I have completed perhaps 500+ hand launches so far, (thru 1999)  and have noted that a sucessfull launch requires about 3 - 5 knots of breeze,  at the minimum.    In calm wind conditions,  running to accelerate the rotor and then shoving the model into the air is an invitation to potential disaster.    In this situation,  without the aid of a breeze,   model reaction is unpredictable.    It may just "fall out of the sky"  (autorotate to the ground).  

To repeat myself,  my recommendation:  that without a slight breeze,  do not attempt a hand launch of an autogyro.    One final note in regard to hand launching and this would apply to any time you want to test your gyro for lift and stability.    With some throttle applied,  hold your model nose high  (30 - 40 degrees?)  and walk slowly into the breeze.    Note not only the "lift" generated by the rotors,  but observe the direction of the lift.    Is it straight up the rotor shaft? Is it pulling to the left or right?   The answers to these questions can give you an excellent clue as to how the model will initially react at lift off on a ground takeoff or release on a hand launch.    When these "lift" clues were present on several sucessive tests,  I have actually "trimmed" the model and found it to launch under realtively "hands off" trimmed conditions. 

Especially during your initial flight experience,  there is an excellent chance you will break a servo gear or two, generally due to allowing the rotors to strike the ground on landing, etc. I might suggest you consider visiting a model car hobby shop,  and purchasing "Servo Gear Savers".    An excellent one is "Kimbrough Products No. 121, Large".    This simple mechanism fits many servos such as Airtronics,   Futaba,  and Hitec,  and can prevent expensive destruction of servo gears.

Should you decide you want to strike out on your own and attempt to design you own model....  it would be helpful if you reviewed the  Specs` and Parameters   page in addition to the new performance charts that we have worked out.  Rick Anderson`s Model Calculations chart will present you with some guidance on power and rotor size requirements.   Jim Baxter`s  Flight Prediction chart will hopefully give you additional understanding the importance of disk loading in regard to flight success.    Just remember that if you go your own way with your own design,  there is not much we can do help you if the model will not fly...  since we would not be able to determine specifically what you have done, right or wrong.   

Try it... you`ll like it

Jim Baxter, 1998-2003 To the   Technical pages
Back to the homepage.. Up dated: 02-04-03 ..jb