GYRODYNAMICS

Have noted ongoing happenings among all you people which narrow down to about basic 3.
Point is these items were uncovered and cured during our R&D which resulted in the Giro V all of
which was detailed in the 2/2000 RCM
Perhaps that is to far back so will breifly report the 3 once more.

1...Stability> maximum stability was found with winged versions ala the early Kelletts etc.
Similiar results were seen with "forward vertical stabiliers" ala as used on Giro V which had
a wing-like seperator for them. Later the "Wing" was replaced with a metal arrow shaft and
performance remained the same.
With wing less Gyros it is a help to have additional forward lateral area, usually as with the
rotor pylon.

2...Airstream Force> one would seldom consider the magnitiude this force presents and that
easily can collapse rotor control linkages and overcome servos.
The force magnitude increases with increases in rotor disc frontal area and with flight speed. Increases are as of a square of the speed and quadruple area increases
Often the problem is seen in flight as changes in circumstances cause the rotor to move full back and be held there.
Solution was to use very robust control linkages, rotor head and a minimum 120 in oz servo
with metal gears.

3...Gyro tilts on take off at lift off time> this factor is common to all autogyros and is labeled
"retreating blade stall" or techniucally a lift differential.
Fortunately the factor is only present during a small portion of the rotor rpm spectrum starting
just before lift off rpm is attained and ending as flight RPM is achieved.
Full scale solution to this problem is to power up the rotor the flight RPM before commencing
take off. The method is called "Pre Spin"
This factor was added to model Gyros and with it hundreds of flights have taken off with no aborts.
Method is to adapt engine starting routine to the rotor. Rotor is equipped witth a propeller spinner and rotor is pre spun ala an engine with a 700 RPM B&D portable hand drill motor.
Note that flight RPM commences at about 350 RPM>
Further note that determining Gyrodynamics at first envolved crashs and rebuilds. A better solution was found using a "car tunnel": The Gyro is attached to the hood of the car and action can be observed at various speeds.
Again, hopefully info will be helpful to many. we need all the Gyro people we can get?
And please don;t forget> Autogyros over Spring Hill February 22-23, 2005
Good luck!

Hal [email protected] .

Thats great info Mr. deBolt. Thanks!

I did not get a chance to read your article in that issue of RCM. I know of your GYRO V model as I saw it listed in the RCM plans catalog.

I am on the lookout for a back issue copy so I can read it over.

Thanks again!

Hi Hal

Item 2 on your list is obviated by using an offset gimbal. I have experimented with various amounts of offset and generally speaking It enables me to use very standard servos that are never overloaded. On a particularly windy day just holding the pitch linkage in my hand I discivered once that the offset was sufficient enough to make the pitch tend to want to move in a forward direction !! This was on a 42" diameter rotor but the size is irrelevant.

Offset gimbals are used on full size and it is this that allows the more thinly muscled pilot to move the pitch of the rotor fore and aft with little or no stick forces.


Cheerio

Sean

Hi Sean,
Good to see you here again, have wondered about you all.
First I have Emailed you several times with no reply??
Will you please Email me and include your Email address? Thanks! [email protected]
I am aware of what you say about offset, we discussed it several times.
In fact I have a Giro V set up with some offset so to investigate. But I can not fly, sad?
Also it seems larger craft see things some differently than smaller ones, thus before suggesting
something it needs to be proven?
At this time what is suggested concerning the airstream force is a proven method so itt is
quite safe to suggest it?
Actually I posted Gyrodynamics because I saw evidence that people were entering the Gyro
phase I have been with and seemingly seeing factors which I initially saw and had to conquer
the hard way. Especially John Warren and Colin Duthie, We need to help each other?
About it, hope all is well with you all!

Hal deBolt

Hi Hal

I read your Gyro V article via RCM’s online archive it is a good article. (anyone with an active RCM Subscription can read it) So as I read it a large surface area pylon will make up for wings for stability? Like a canopy/pylon combo. Like in this one http://www.autogyro.com/models/g-too.htm

Or http://www.rcuniverse.com/forum/upfi...73/Ig11184.jpg

SG

What incidence angle for the rotor blades do you use on your autogyros? I am using a flat bottom airfoil with reflex.

SG

Hi to all of you

let me introduce myself. I'm a newbie from France. I'm just fascinated by gyros and try now to make one myself.
Some of you may find it stupid, but i'm not keen on ready-to-fly kits, although suited for beginners. I prefer the thrills of making my own mistakes.
I hope, i can convert my flying skills as a plane pilot into rc piloting.
I have been in touch with Mike Smith from aerobalsa for months, and I wonder how fast will a 70" rotor spin (SG6042)?
Can anybody answer this question please?

thanks for your support

best regards

Hello fellow gyroplane enthusiast !!!! Rotor RPM is dependant upon several factors, including blade incidence, blade airfoil, rotor plane angle, rotor system airspeed, and load (weight) acting upon rotor system. It may be hard to predict the actual rotor RPM without experimentation. Good luck with your gyro trials and happy flying !!! Charlie Anderson

Hi ottogyro58,

thank you for your quick answer
I don't need a very accurate answer. I just need to know an approximate speed range, in order to design the blade mounts. Neither too heavy, nor too weak regarding the dynamic stress on them.

regards from Alsatia

Hello !!! I would guesstimate a rpm range of 400-800 rpm with 1000 on the high end. Good luck with your new rotor system and please keep us informed of your progress. Thanx !!! Charlie Anderson

hi ottogyro58,

I will post the results here, but don't expect them for this year. I first need to have the blades, and this depends on how quick aerobalsa can respond to orders.
I will surely be back with questions before I come with answers

bye

Hello All,

Does anyone know where I can get polypropylene sheet for hub hinge material, from a local source. (central Florida)(is that what a coffee can lid is maid out of)??????? Is there a better cyclic loading flexible material then polypropylene? For those who have tried this material what thickness would you use for a .40 sized gyro? I was thinking about .030� to .040� I’m using www.autogyro.com for help on a lot of the design. My gyro has all ready flown successfully how ever the flapping hinge hub is not that I built was not that great. I could use Hal’s design from the RCM gyro 5 but It would require an Aircraft Spruce order ($$ shipping & a long wait) for aircraft piano hinge.

SG

SG,
Where are you in Central Florida.

Jim

Daytona, but i go to Orlando, Jacksonville, and Merit Island alot

SG

SG,
I am going to Deland this weekend.. I have used the (# 5 recycle mark) containers from WalMart. But I think they do stretch a little. Bill F has sent me some good polypropylene ..It should be availible in the big cities without buying a big sheet.

Are you going to Spring Hill this month?

Jim

What is in spring hill?
SG

SC,
The Annual Spring Hill Auto Gyro Meet. Feb. 23-24 Thursday and Friday.. Saturday and Sunday is Vintage Airplanes.

Jim

For .030 or .040 polypropylene, go to www.mcmaster.com, on the home page in the bottom right corner,under raw materials and springs, click on plastics > film > polypropylene > thickness. A 12" x 12" X .030 thick piece is $5.64. I also use Garolite grade 10, for the mounting pads on my blades, you can check out the specifications for it on this website also. I also buy my 4/40 socket head capscrews here to by boxes of 100. Usually get my order in about two days. The only problem I have with this web site, is that I usually end up buying more than I had planed on. Also, if you send me your e mail address, I can send you pictures of a rotor head that just might work on your gyro.

Neat web site,

Looks like he carry’s a ton of stuff I like the verity of sizes they carry. They wouldn’t happen to carry the Hillman T nuts with 3 holes instead of 3 spikes would they? The thinnest polypropylene I could find is 1/16� on the web site and locally. I ran in to a dead end at the local Daytona plastic shop 48 x 96 is there smallest sheet and it was over 40 bucks so I skipped that. Enough material for 40 hubs. I’m trying out a Kevlar hub with a carbon disk as a rotor drupe stopper. The lay-up is curing on the mold plate right now. My hallow molded e-glass / Carbon blades have worked great, if the Kevlar hub doesn’t work ill give mc master a call. I’m assuming that Polypropylene goes to run out in cyclic loading like spring steel, I know Kevlar will work in that respect.

Thanks for the info

SG

Rcairplanenut, try going back to the mcmaster web site again, you must have looked under sheets of polyproplyene, look under "FILM", thickness goes all the way down to .005

Found it i was looking under sheet before

Thanks

sg

Here is the new composite hub, I will have to do spool up test and see how it works out

Sg

I found the T nuts in 50 bluk pak on mcmaster I have been looking forever for those. Thanks for the web site.

Hello all,

I Had the first full flight my Gyro 2day, there where a few test hops in November 2004. A 5 minute and 2 minute flight. It fly’s great but I cracked the epoxy on the Kevlar hub, so I will be giving Mc Master a call some time soon for some polypropylene. Since the rotor blades are maid from a molded composite I think I will go to 4 blades and make them slightly shorter for better tail clearance. www.autogyro.com and Hal’s Gyro 5 article help make this project a reality.

SG

I have a rotor hub that is almost idenitical to yours. My blade holder is made from garolite grade 10/f4, and have had some spetacular crashes, and have only broken the blade holder that was converted into a delta hub. My curent blade holder is made from 1/8 material, and that is to stiff. I have purchased 3/32 material, but have not made the new blade holder yet. I to have purchased polypropylene for the blade holder, and as of yet, have not made it. I will bea trying to contact you personally for your email address.

Gary Ten Pas