Discussion Beginner Autogyro/Gyrocopter/Gyroplane Questions and Answers

[mnowell129]

Ok, 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 and
come up with something that we can live with so we
don't have to answer the same questions over and over.
So what I ask is that if there are corrections, let me know and I
will 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.....
mick

Gyrocopter Questions

1) What is a gyrocopter,autogyro,Autogiro,gyroplane?
A rotary winged aircraft that derives lift from a non powered
rotor(s) and is pulled (or pushed) forward by a conventional engine/propellor.
The names mean the same thing but are various marketing/registered
names for brand name aircraft. (all Kleenex is tissue, but not all
tissue 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 blades
on top of my airplane?
YES and NO, respectively. Most heli blades are the wrong airfoil
and 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, what
do you suggest?
Not to. Build a gyro from plans or a kit first to learn the different
flight 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 by
the area of the whole rotor disk. ~2-3 Ounces/sq foot for
two bladed systems, ~3-4 ounces per sq for 3 or 4 bladed systems.

8) Are there kits? Plans?
Yes
The Slow-G twin http://www.slow-g.com/
The PtGyro family : http://www.flyingbalsa.com
G3PO,BEGi and GT17: http://www.mickeynowell.com
Several from Arizona Autogyro : http://www.autogyro-rc.com/
The DAG01 http://home.att.net/~imsofaman/dave_...c_homepage.htm
Whopper
the plans:
http://www.vth.de/Modellbau/FMT/dow...t_downloads.asp
direct link to part1 and 2 of the plan:
http://www.vth.de/Modellbau/FMT/dow...Whopper%201.pdf
http://www.vth.de/Modellbau/FMT/dow...Whopper%202.pdf

link to the thread at rcgroups:
http://www.rcgroups.com/forums/showthread.php?t=487131

link to german thread incl. comments of creator:
http://www.rclineforum.de/forum/thr...c7b3a355edcd0e9

Mini/micromum
here's the link to the latest version of the Micromum plans:
http://www.rcgroups.com/forums/show...79&postcount=69

and this one is for the Minimum:
http://www.rcgroups.com/forums/showthread.php?t=543196
Twirl : http://www.rcgroups.com/forums/showp...3&postcount=63

9) Where is more information?
Almost any question you might ask has already been answered
at one of these places. Use the search feature to
look for specific words like "collective pitch" or
"direct control" or "advancing blade" and you will
find many questions and answers.
http://www.autogyro.com/
http://www.rcuniverse.com/forum/forumid_191/tt.htm
http://www.rcgroups.com/forums/forumdisplay.php?f=224
http://www.runryder.com/helicopter/f59p1/
http://rchangout.com/forums/forumdisplay.php?f=113

10) 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 and
it won't fly. What's wrong?
Gyrocopters don't scale well, namely the mast angle has to
change, the blade pitch has to be negative rather than
positive and the control systems have to change to
allow for the increased control response from the rotor
when 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, then
decide 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, especially
with 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 skill
level. 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 Gyros
are great. If you have advanced skill and/or have flown helicopters
G3PO and BEGi are good performers. None of these models are appropriate
for 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?
Yes
Generally in March at Spring Hill Florida,
September in Muncie Indiania and
new 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 condition
where the rotor is not just windmilling slowly but turning at a very
high rate. In this condition the centrifigal forces are high enough
for the rotor to be stable and it is producing enough lift to fly
and keep it self spinning. It is important to get the rotor into
autorotation before flying and allow the model to fly on its own
without up elevator.

17) What are the different rotor configurations like?
Single uncontrolled rotor : Very difficult to get to fly well. Requires
careful 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 by
RET. 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 but
the 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 and
capable 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 horizontal
stabs to make the aircraft stable. Need heavy duty (metal gear) servos.

Single "Heli" Rotor : More complicated head design, requires attention
to detail in assembly of the rotor head. Very stable rotor so
model doesn't need horizontal stab. Very manuverable, especially at low
airspeeds. No special servo requirements. Some parts must be commercially
purchased.

Hybrids : There are combination designs, such as a tilting spindle head
with 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 because
it has to spin much faster and has less mass. The controls get too sensitive
for 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 helicopters
and this is the reason the model helicopters have flybars, to tame the
high control rates that don't exist in full sized aircraft. This principle
can be illustrated by trying to balance a broom in the palm of your hand
and 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 positive
angle 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 purpose
built 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 different
angle of attack.

21) What is the advancing blade? Asymmetric Lift?
This is the condition where the forward going blade is getting
more 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 successfully
you have to apply cyclic pitch so the advancing blade has less angle of
attack than the retreating blade. The cyclic pitch can be either "flapping"
with a flapping hinge, or "feathering" with a feathering hinge. Un-controlled
rotors use flapping hinges, or in the case of dual rotors let the asymmetric lift
cancel each other out. Controlled rotors, tilting spindle or swashplates, use
feathering to cancel asymmetric lift. This is a slight amount of down elevator
in either case. This is an advanced topic with lots more to read in the references
above.

22) Where should the CG be? What is the "hang angle"?
The CG should be directly below the center of the rotor when it is
placed horizontally, or slightly ahead of that with models that have
a horizontal stab. This gave rise to the concept of "hang angle",
method that describes how far down the model hangs when hung from
the 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 getting
the 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 more
sensitive. 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 airspeed
which is ususally pretty low. Downwind turns and downwind passes
tend 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 wind
because 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 have
a limited glide angle (about 1:1, or 45 degrees down), but you can flare
to a zero rollout touchdown. Elevator controlled models are usually
less controllable with power off and tend to be built light so they
can 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 overall
flyability, although it does reduce the spin up time. The added
complexity is for advanced modellers.

29) What about pre-rotation?
Most models use the "hand flip" method. Some models have
used a drill or other motor to spin up. There are no models
that have built in pre-rotation, but I'm working on it.

[mnowell129]

No fair you sneaky readers. If you're going to read please comment yea or nay... either to specific items or the entire idea.....
If you are newbie please add questions so they can make it into the FAQ.
I'm just trying to help us all, newbies get a set of answers, oldies don't have to answer the same set of newbie questions....

[PT Gyro]

Hi Mickey,

I think this is a great idea.
You have also covered the basics very well.

One item that may need to be added is that Mike from Aerobalsa has some plans available since taking over the autogyro.com website.
This should be added to the "Kits and Plans"

Take care,
John

[mnowell129]

Originally Posted by PT Gyro

Hi Mickey,

I think this is a great idea.
You have also covered the basics very well.

One item that may need to be added is that Mike from Aerobalsa has some plans available since taking over the autogyro.com website.
This should be added to the "Kits and Plans"

Take care,
John

I saw that he was going to have the plans, but don't see them listed. Does anyone know what he has and how to get them?
mickey

[rcflyerfl]

Mickey
Nice job. If all would heed and build a proven model first, they would lot's more fun.
Might add what getting into auto-rotation is so they will know when it ready to take off. Not just power up and try to go.

Thanks,
Jim

[tnt2000]

Mickey,
If you did this earlier, I would have succeeded after very few trials....
I am getting close and hooked onto it.
Thanks for sharing great start point.

Junhee.

[johnvb]

OK, here's a question from an experienced fixed wing flyer but an autogyro newbie:

I'm looking for a brief description of all the different head/rotor configurations and their capabilities.

[iter]

Yes. Among others, Stacy Gillmore has done a Slow-Stick Flying Boat conversion with Slow-G rotors.

More details here: http://www.rcgroups.com/forums/showt...04#post5578790

[mnowell129]

Originally Posted by iter

It would be excellent if we could make this thread sticky, and have someone with permissions to delete chitchat (like this post) after say a week. It would work best if we kept this thread short and digestable, like the index thread over in the micro forum (http://www.rcgroups.com/forums/showthread.php?t=84771)

Ari.

I agree. I plan on making it sticky and deleting the chatter after about a week. I thought I'd give it a week so all the regular posters could comment and help me with stuff that I might have missed. I often write professional documents that are peer reviewed before release, I thought I'd extend the
same courtesy to you guys. You know how it is when there is a single author trying to represent many opinions, sometimes toes get smashed

[mnowell129]

Edited the opening post to add some questions and answers.
Thanks to all who have contributed so far.
mickey

[M. Smith]

All,

I will be adding plans to my website soon. Here is what I have:

Simple G
Sparky
Twist
Suitcase Minnie
Cierva C30
Delta hub, 4-blade for .25 size model

All are 1-sheet plans except for the C30, which is a 2-sheet plan. For now, pics and instructions are on Jim Baxter's Autogyro.com website. The plan sheets are available from me. Anyone interested can email me directly until I get it all listed on my website.

Mickey, your FAQ is great. Thanks for your thoughtful contribution to our hobby.

Mike Smith

[mnowell129]

Originally Posted by M. Smith

Mickey, your FAQ is great. Thanks for your thoughtful contribution to our hobby.

Mike Smith

Thanks, and you're welcome.
I'm having fun.

[dougmontgomery]

This Is great, Good job Mick.

[Bsouthwell]

Mickey,
The FAQ is great!! Very, Very good! Thanks for your fine work. I have got to give the Gyro's a try.

Bill

[mnowell129]

Originally Posted by Bsouthwell

Mickey,
The FAQ is great!! Very, Very good! Thanks for your fine work. I have got to give the Gyro's a try.

Bill

You're welcome. Nice to see someone from home. My family is from Kosciusko, I grew up in Jackson, went to school in Starkville, still have family in Carthage and Grenada.