hi hillberg,
in fact I was wondering if a heavier rotor was ot more difficult to bring at flight rpm then his wooden rotor ?
you right it is not a question of material
cheers
G

Blade profile is what's important not the material of construction

Map out the airfoil shape for performance

Sorry Giro, been busy, and the thread title didn't lend itself to checking.

I don't mind balancing on the mains, but I don't do it much anymore.

I doubt you are asking about hand patting procedures, but are more interested in normal takeoffs.
After I am in flight mode, I taxi to a run up area, disengage rotor brake and give the blades a small spin up...Not flight speed! This lets me know theres no strange vibes or bangs and bumps coming. Do engine/control checks. Reengage brake. Make sure at an airport you algin blades fore and aft!!!! If tower tells you to hold short for traffic and they turn at your taxiway, tower will not see your blades.
Once I have the active, I always remind tower it will take a min to spin up...
Go to the intersection (widest part) and turn into wind (almost always 10-15kts from my 2 oclock position) flatten rotor disk with stick full forward. Increase throttle a bit, and engage slowly but smoothly the pre rotator. When blades are spinning as a blur or about 200-220 rpms I smoothly start to bring back the stick. If you have an rpm gauge you will watch the rpms decay immidiately, release brake pressure and begin roll no faster then a man walks and as soon as you see the rom decay reverse and start to build you can go a tiny bit faster, or add more disk back.
Keep doing this until your nose wheel gets light. As soon as the nose wheel is up increase throttle and speed togther. You do not need fast forward motion if the rotors are moving fast.
I like to hop off ground and let rig weathervane 5 feet off ground. Flatten disk and pick up speed in "ground effect" until I am at full speed then climb out.
This is from an airport with a massive runway complex.

Hi Henry, That procedure seems the best of all worlds. I'd add that if the blades don't seem to be accelerating if you lift the stick just off full back it will tell you if they are starting the hinge(flap) you only feel blade flap (hinging) when the blades are colliding so badly they are bending the mast on each strike of the teeter stop. By this point you are often only a second or two from smacking them into the ground. In open frame gyro I used to feel the breeze on my face (about 8-10mph) was enough initially. Then once they really started to pick up up to 12mph then after they picked up again they were pretty much beyond hinging. Sounds like you have excellent blade management.

Indeed it is I ;)

Girodreamer and I have managed to catch up since the first comment and suggested this thread. Mad Muz we're in the same state have we met? Seems like we might have traveled in the same circles. I found a couple of the comments above I might throw an opinion in glad to be a member. Please forgive me if I don't know how to use the forum well for a bit.

hi all.

I am happy that your are here with us, we are not numerous, we are not experts, but we have a lot of fun together, this forum has strictly no other goal then being a friendly space .

hi
I had told him that we were cool people !
A new kid on the block !
The forum is becoming an Australian gyroplane club hahaha
I hope he will show us Ozzies surfer babes !
welcome aboard
jean michel

Benry, Cameron,

I completely agree with you .. but I have two problem with your method :

- the first is that I have never been trained to "feel" the rotor reaction as both of you obviously have

- the second is that my blades weight 16 kilos each , and my rotor is 7.7 m in diameter (nothing to see with a superb wooden rotor like yours)

this is why need to work my rotor management .. before attempting to take off in your manners folks .... lack of education

Cameron ... when your glider is ok, and you club back in activity .. I'll come and get training from you if you accept me ... I am not kidding


Yes probably wise. There was a suggestion above. When I've flown in gyros with bigger blades and pre-rotators the technique is similar you pre-spin up until they are fast but they don't need to be ridiculous. You then taxi forward slowly enough to feel a breeze on your face around 8-10 mph. The blades should start to accelerate, if they don't there could be two reasons one you don't have enough speed (be careful of that one) and two you have too much speed and your angle of attack is too high on the retreating side. If they are accelerating its all good keep doing this until they don't keep comming up faster then add another couple of mph say 12mph they blades should be accelerating faster now. At this point they will start to blur and your machine will start to resist forward motion on little throttle so you add more throttle the blades are likely over the hump not likely to flap (hinge) anymore unless you do ridiculous things at this point again add a little more now you are doing 15mph if they are a blur they aren't going to flap. From this speed my old VW would lift the nose and I ceased worrying about blade speed because I could gun it from here and they won't hinge. The inertia will have an impact I think both of my blades together are about 16kg I must weight them they might be heavier but they are significantly lighter than my metal blades. Anyway the time is all you need blade length is probably more an impediment than actual mass (although it will effect it). The good thing about this method is the fundamental principle you are trying to follow is keeping the angle of attack of the retreating blade as low as possible throughout. Pushing the blades with too much airspeed too soon increases angle of attack and drag which reduces autorotation and slows time/distance to wind up. So you are trying to add a little speed at a time only. If you look back at the first video thats what Steve was doing there was bugger all wind that day and they'd all do take offs like this every time. In strong winds they spin up even quicker. The key to that take off was the slow start and hence less runway being used.

If you wanted to experiment I'd make a couple of suggestions. If you have a park brake use it if not build some wheel chocks. Park in some safe area on a day with a bit of wind but not too much a nice steady breeze. rig some sort of wind sock at least 5 m ahead of you as you'll know a thermal is coming through before it hits your rotors. Have a mate with a radio stand beside or in front of the disk just to watch the distance to the rear of your rotor. Once you've wound up the rotors to what you think they might get in a single seater by hand or a little more but don't go to 220rpm - sorry never used a rotor tacho so don't have much guidance I'd suspect 100rpm would be fine. Now once up turn off your engine so you can concentrate on the rotors only and so if they do hinge(flap) they most likely won't hit the prop. Gradually ease the blades back to full back if its a stonger wind say 12-15mph you will need to gradually bring them back as 15mph is enough to hinge them at low rpm so you hold a shallow disk angle they should either maintain rpm or start building. You can then ease back stick and observe if they are maintaining but not climbing you have gone too far if they are descending you haven't pulled back far enough and this is the key point. When your blades are hinging they bang the stick around violently. Why does this happen and why is it so violent? Its violent because if you have the stick full back the blades when hinging hit the stop at 180degrees (full back position if 0 degrees is full forward) because the stick is locked on the back stops the mast absorbs the impact until it is so violent that it is actually bending the mast around is a circle following each rotor as it goes to retreating then forward. So the circular stick motion is actually the mast moving around (consider the forces involved to do that!) and this is pulling the control rods around which is translating into stick movement. If you stick is not fully back then hinging will appear gently at first as a tap, tap, tap if this happens full forward stick straight away! However if you pull back to full and just hope they are not hinging then you won't know until its developed fully. Now you don't want to wind up with the stick not fully back so what you do is watch the blades and if they don't seem to be spinning up then you bring the stick just off the back stop if they are just starting the hinge/flap this will manifest as stick movement but not fully developed cut power full forward stick etc.

Now you also need to develop the mental picture of your rotors winding up normally. The should make a nice circle in front of you from your perspective it should be a nice circle what you are used to seeing. However when they are hinging they are lifting up then diving back the blade will sort of whoosh up at the nose so at 0 degrees they will be higher than the normal circle then sort of swoop down. Its subtle but its there and its the first sign once you have that mental picture in your head that's the first clue, but you'll probably learn to know when they are decaying or accelerating first.

If you did want to experiment just let you know what you should see. from the outside side on it will look like a giant S shape rear swinging to the ground front swooping up the observer should be looking for the back of your disk getting close to the ground at which point they should call you off. If they are standing at 3/4 looking to the front they should just look for the disk getting low at the back if its getting close to the ground you are getting into hinging.

Watch this video this is one of the gyrogliders I used to instruct in, the club is opperating out of a different airstrip but the driver here is too aggressive and they start the blades hinging/flapping. watch from 47 seconds to about 53 seconds where the instructor signals to not go any faster. I'm not criticizing here this stuff can happen particularly with an inexperienced driver or observer I was trained to look for this low disk angle when I was observing. if the disk isn't a few feet off the ground you are hinging/flapping. Again not a criticism and the instructor has picked it up and corrected for it. I had a driver who was lead foot and would often put me into this sort of position. It will be easier for you as you will be controlling your own speed. If attempting wind up primarily with wind find someone you can trust and show them this video. They were about 2 seconds from hitting the ground here. Get your observer to correct you long before you get this bad.

https://www.youtube.com/watch?v=6GqHCIzVFNU

So once you can wind up stationary in wind you'll have learnt what speeds your rotors need to get up to speed. then you just translate that into movement on the ground to match that speed. If you find your rotors wind up at 10mph minimum then when taxiing only do 10mph minimum initially if they only get so fast at 10mph then top off at say 150rpm and when a gust at 12mph will get them accelerating then that's the next stage. etc. But go easy, blades are bloodly expensive.

Giro, the key to this all is you move forward way slower then think. No faster then an old man at a Golden Corral on prime rib day.
I mean slowwww

Why thank you, that may be the nicest compliment I have had in a long while!
Perhaps a new way to greet gyro guys?
"You sir, have great blade management!"
"Ahhh yes, why thank you my good man!"
Sou ds positively gentile!