Rotary Wing Forum  

Go Back   Rotary Wing Forum > Rotorcraft > Flight Testing

Reply
 
Thread Tools Rate Thread Display Modes
  #46  
Old 05-26-2010, 03:03 PM
Resasi's Avatar
Resasi Resasi is offline
Gold Supporter
 
Join Date: Jul 2007
Location: London/ Kilifi Kenya
Posts: 6,029
Default

Good video, thank you.
__________________
Leigh.
Reply With Quote
  #47  
Old 05-26-2010, 05:58 PM
SideKick's Avatar
SideKick SideKick is offline
Member
 
Join Date: Apr 2007
Location: Hebron MD
Posts: 332
Default

It also broadened my understanding, thanks
Reply With Quote
  #48  
Old 05-26-2010, 06:15 PM
GyroRon's Avatar
GyroRon GyroRon is online now
Shut up and fly
 
Join Date: Oct 2003
Location: Fort Mill South Carolina
Posts: 15,513
Default

I was told to never allow the blades to go slower than what they turn at the point of lift off. With the old engine the gyro would lift off at 260-270 RRPM, and I could easily get the rotors to 270 in flight by holding the airspeed at or close to zero and at high power setting. The gyro now lifts off about 275-285 rpms and I have again seen 270 in flight with only about half throttle and zero airspeed. I am afraid to see how slow I can possibly get them to.....
__________________
...Ask me and I will tell you..if you don't want to know then don't ask.
Reply With Quote
  #49  
Old 05-26-2010, 11:08 PM
birdy birdy is offline
Platinum Member
 
Join Date: Mar 2004
Location: Alice Springs-central Oz.
Posts: 5,292
Default

Birdy if you get the blades too slow, they loose their stiffness and you can flap them
Then flapn is the rong term Ron.
Fold would be more accurate.
but i dout that would be possable.

But in my own gyro with the long rotors and the amount of thrust my engine produces, it is very easy to slow the rotors to a rpm lower than the lowest rpms shown at lift off. I have avoided allowing them to go any slower as I was warned by the manufactor of the blades that at this slow of a speed they loose their stiffness and can flap or even buckle.... bad things would happen in other words.
A rosco witha a 912 is hardly a slug Ron, and iv spent hundreds of hours at full tap, just before sink, and iv never floded or buckeled a blade yet.
Like i said, it aint possable.
Wot is possable is over stressn the hub bar through too high a cyclic rate for the low rrpm if the machine pitches too fast.
Besides, CB says that a rotor can regain flyn rpm from as low as 50% normal rpm without too much hassle. Thats alot slower than the regular "horse it off" rrpm.

But what your saying is no matter how powerful your engine, nor how light your blade loading is, you can pull back stick and slow to zero airspeed at full power and there are no issues to be concerned about?
Been do'n just that for years Ron, And hold it at WOT, sinkn steady, almost to the ground and never hada problem.

Everythns relevant Ron.
High loaded rotors will have high flight rrpms, high min rrpms, and high min lift off rrpms.
low loaded rotors hare the same.
Its the percentage of veriation that counts.
If the blades a set to fly XX machine at XX load, they gouvern the rpms that suit the variants.

I dont have the advantage of a rotor tac, so i cant give numbers, but a regular move the ferel goes through many times a day is,
top off from a virtical climb, level the disc [ horisontal] , apply full power and go strate into a full power virtical sink. Itd start loosen rrpm at the bottom of the climb, loose more at the top, more from the rapid, high cyclic at the top, and more still till the decent start to steady. mite b e a good thing i dont hava taco, coz id probably never do it again.
Yes, they are ' mushy' till the rrpm catches up, but iv never floded/flaped once.
__________________
Ignorance is bliss, but only till you realise you were.

VPR, the ultimate.
Reply With Quote
  #50  
Old 05-27-2010, 03:44 AM
Fl90's Avatar
Fl90 Fl90 is offline
Gold Member
 
Join Date: Jun 2006
Location: Lake Placid, Fl
Posts: 1,721
Default

there's mushy.....and then there's MUSHY. I just got a machine with a rotor tach, and a bunch of other dials. I'm thinking of taping over them to keep my blood pressure down!

Phil

p.s. maybe a bigger rudder too.
Reply With Quote
  #51  
Old 05-27-2010, 04:25 AM
C. Beaty C. Beaty is offline
Gold Supporter
 
Join Date: Apr 2004
Location: Florida
Posts: 7,206
Default

Whether or not a rotor will flap catastrophically depends upon airspeed and the angle of flow through the rotor disc.

During rotor startup, flapping would be eliminated if the rotor disc could be tilted back 90º so that edgewise flow was eliminated. It would either start or slow down.
Reply With Quote
  #52  
Old 05-27-2010, 06:36 AM
MichaelBurton's Avatar
MichaelBurton MichaelBurton is offline
Gyro CFI
 
Join Date: Oct 2004
Location: Pleasant Grove, Utah. USA
Posts: 1,108
Default

Quote:
Originally Posted by C. Beaty View Post
Whether or not a rotor will flap catastrophically depends upon airspeed and the angle of flow through the rotor disc.

During rotor startup, flapping would be eliminated if the rotor disc could be tilted back 90º so that edgewise flow was eliminated. It would either start or slow down.
I guess I don't quite understand what you are saying.

Please explain
__________________
‘‘The Laws of Aerodynamics are unforgiving and the ground is hard.’’ Michael Collins (1987)

"A well designed aircraft is important but no substitute for proper knowledge. attitude, and experience. " (2011)

Click here to Join group and contribute photos

Photos by Michael Burton
Instructor and PRA event map
More about Michael Burton



Michael Burton
801.769.6404
Reply With Quote
  #53  
Old 05-27-2010, 07:06 AM
getut's Avatar
getut getut is offline
A 'lil twisted
 
Join Date: Oct 2006
Location: Salisbury, NC
Posts: 668
Default

Sounds like he's saying that if ground and tail behind the gyro weren't the limiting factor and you could rotate the blades back all the way (think drag chute or a gyro in a vertical descent) where the advancing air was hitting the bottom of disk straight on rather than mostly edge on like a normal takeoff.
__________________
.
Flying is the most fun you can have without being forced to cuddle afterwards.

Fishermen:
Fish from the bank, cast as far out as possible and dream of having a boat. Finally get the boat and ya start fishing toward the bank.

Gyro Pilots:
Stand on the ground stare into the sky and dream of one day flying. Get a gyro and ya start flying close to the ground.
Reply With Quote
  #54  
Old 05-27-2010, 07:22 AM
C. Beaty C. Beaty is offline
Gold Supporter
 
Join Date: Apr 2004
Location: Florida
Posts: 7,206
Default

Quote:
Originally Posted by MichaelBurton View Post
I guess I don't quite understand what you are saying.

Please explain
A rotor will recover from lower rpm in a vertical descent than with translational airspeed.
Attached Thumbnails
Click image for larger version

Name:	flap.JPG
Views:	130
Size:	14.7 KB
ID:	69938  
Reply With Quote
  #55  
Old 05-27-2010, 08:29 AM
MichaelBurton's Avatar
MichaelBurton MichaelBurton is offline
Gyro CFI
 
Join Date: Oct 2004
Location: Pleasant Grove, Utah. USA
Posts: 1,108
Default

Quote:
Originally Posted by C. Beaty View Post
A rotor will recover from lower rpm in a vertical descent than with translational airspeed.
I understood that and have seen it many times.

What I was having problems with was that 90 deg. Statement but now I think I understand. If the disk were tipped back far enough it would be the same as a vertical descent and there would be little or no flapping required as there would be no difference in the air velocity over the airfoil induced by the movement of the gyro. That is intuitive to me but I did not see how it would be applied to the situation of a low G flapping / mast bump event. Thanks for the graphic.
__________________
‘‘The Laws of Aerodynamics are unforgiving and the ground is hard.’’ Michael Collins (1987)

"A well designed aircraft is important but no substitute for proper knowledge. attitude, and experience. " (2011)

Click here to Join group and contribute photos

Photos by Michael Burton
Instructor and PRA event map
More about Michael Burton



Michael Burton
801.769.6404
Reply With Quote
  #56  
Old 05-27-2010, 06:17 PM
Redbaron's Avatar
Redbaron Redbaron is offline
Platinum Member
 
Join Date: Apr 2009
Location: earth
Posts: 2,567
Default

sorry for not respondin, had a stomach virus for a few days and felt like crap. the airspeed specs on my bee aren't much off from ralph taggarts original bee! this isn't voodoo lol my disk loading is light! ron your welcome to come over anytime, pm me when your free. it will fly slow under power maybe It was 10-12 mph hell I don't know its pretty neat to go that slow tho! got some rotor shake above 35mph, need to clean those bugs off. she doesn't like to go real fast thats for sure
__________________
Friends don't let friends drive pitch or torque over unstable gyros.
Reply With Quote
  #57  
Old 05-27-2010, 06:24 PM
Redbaron's Avatar
Redbaron Redbaron is offline
Platinum Member
 
Join Date: Apr 2009
Location: earth
Posts: 2,567
Default

I only went that slow under dead calm conditions! fly fast in strong thermals then you might see your rotor tach dance!

Quote:
Originally Posted by Fl90 View Post
there's mushy.....and then there's MUSHY. I just got a machine with a rotor tach, and a bunch of other dials. I'm thinking of taping over them to keep my blood pressure down!

Phil

p.s. maybe a bigger rudder too.
__________________
Friends don't let friends drive pitch or torque over unstable gyros.
Reply With Quote
  #58  
Old 05-27-2010, 10:14 PM
RotorTom's Avatar
RotorTom RotorTom is offline
Gold Member
 
Join Date: Feb 2008
Location: The Wild West
Posts: 788
Default

Is it me? Or does he just not make any sense?
Reply With Quote
  #59  
Old 05-28-2010, 04:13 AM
Fl90's Avatar
Fl90 Fl90 is offline
Gold Member
 
Join Date: Jun 2006
Location: Lake Placid, Fl
Posts: 1,721
Default

Just doesn't have a solid understanding of the gyro.

Best thing to do is keep him in discussions and feed him info as politely as possible. He is already flying, and this is a good source of information for him. We just need to keep him reading till it sinks in.

I hope I don't have to contribute to the flower fund.

Phil.
Reply With Quote
  #60  
Old 06-01-2010, 08:41 PM
Redbaron's Avatar
Redbaron Redbaron is offline
Platinum Member
 
Join Date: Apr 2009
Location: earth
Posts: 2,567
Default

sounds like you need some more brain food, I have a good understanding! you have been brainwashed by those " unstable gyros" that they are super unstable and dangerous lol

Quote:
Originally Posted by Fl90 View Post
Just doesn't have a solid understanding of the gyro.

Best thing to do is keep him in discussions and feed him info as politely as possible. He is already flying, and this is a good source of information for him. We just need to keep him reading till it sinks in.

I hope I don't have to contribute to the flower fund.

Phil.
__________________
Friends don't let friends drive pitch or torque over unstable gyros.
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -8. The time now is 06:52 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd.
Ad Management plugin by RedTyger