hand starting rotors

Redbaron

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whats the dos and don'ts of hand starting rotors? do instructors teach this? I've seen jon hand start his gyronimo on youtube! Whats the first onset of blade flap in wind? :bored:
 
First I am a novice at this so keep that in mind. When starting and until the rotors get to 100 -120 rpm you have to limit the angle of attack of the rotor blades as they come up to speed. Relative wind speed 5 -10 mph no more. Imagine looking at the plane of the rotor blades from the side. The high point of the plane should be in front of the gyro into the wind. Low point at the rear. This plane should be steady and the hub bar/rotors are not tilting about the teter bolt. If this plane changes and the high point moves from the front around to the advancing blade side you are getting close to flapping and have to reduce the angle of attack of the rotor. You will see the hub bar/rotors moving about the teeter bolt. Once the rotor has all the rpm it can get with this relative wind ie the rotor is tilted back to max and maybe the gyro is also tipped back on its rear wheel and the plane is steady high in front low in rear then more relative wind can be induced ie taxing faster but only go 5 mph faster until again max rotor rpm for this speed is achieved. Then go 5 mph more.

This is why it takes a lot of runway with light headwind to get the rotors up to speed. If the wind is blowing 20 mph down the runway then most of the rotor speed can be achieved before the gyro even moves forward by just controlling the angle of attack and avoid flapping until the rotors achieve all the speed they can get.

For me the hard part was understanding that with only 5 mph releative wind speed you need to get the rotors up to 100 rpm plus before adding more relative wind. And then only about 5 more mph wind in increments until you work the rotor rpm up to over 200 rpm. Then the rotors acclerate quickly with added relative wind increase.
 
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Let me back up just a little. When I get ready to start the rotors the stick is full forward. I tie mine because I cannot hold it and push the hub bar at the same time. When you start to push the hub bar around the first thing you notice is the blade that is advancing into the wind wants to rise pushing the opposite side down. They are starting to teeter which you don't want. When you are pushing on the hub bar you can counteract this by pushing slightly up on the side that wants to come down and you also are pushing to increase the speed. Once you get the rotor going as fast as you can by hand I get into the seat (strap in) and untie the stick. You just keep letting the stick move slightly back as the blades pick up speed very small amounts like half an inch or so. If the high part of the rotor plane starts moving around toward the advancing side the blades are starting to teeter and are going to flap ie hit the teeter stops pretty soon. You have to push the stick forward enough to prevent this. You just slowly let the blades get faster and faster till the stick is all the way back. Then you can also lift up the front of the gyro for more tilt. You should get about 100 rpm from this and you will hear the blades going fast enough to start the swishing sound.

I recommend one does this with the gyro tied in the front to something and without the engine running if you have a small breeze say 5 mph or less. Do this several times maybe 5 or 10 so you can get the feel for the blades starting to come up to about 100 rpm. You can get this rpm in a very slight breeze. This is the time that is most critical for blade flapping. It will give you a chance to see and hear what the blades are doing.

If the wind is faster that 5 mph the you can get higher and higher rpm. Just get all you can. Push the stick forward and the blades will slow down to the speed you acheived when hand pushing. You can then stop them by hand if necessary and start over again. I have been doing this quite a bit lately playing with the pitch on the blades. 0 deg or -1 makes them start and stop easier. Wind higher than 5 mph is harder to get the rpm up without flapping. I have done it with the pitch at +2 deg and 20 mph wind but it requires a lot of patience because the blades just don't want to pickup speed. You have to really nurse the stick back slowly to get to that 100 rpm without flapping.
 
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Lots of do's and dont's and some very good threads on the forum that you can search for with the forum search tool.

Instructor's certainly should teach this as it is a part of rotor control.

First indication will be a ticking of the rotor hitting the rotor stops and the stick beginning to twitch. This does progress quite quickly to a violent stick movement with the blades flapping/flexing and possible ground or airframe strike. Get the stick forward, throttle off, and stop the gyro.

From another novice, for a novice John a pretty good description.

I found that in a very light or no wind my blades will start slowing quite fast as soon as I stop patting them. In this case I quickly get into the seat and before fastening in, start the gyro moving forward very slowly to provide some incoming air to get them past the rpm where blade sail/flap starts, then stop and fasten in. If I took the time to fasten in a four point harness I simply could not get them up to speed. I find sometimes one does have to be patient as it can take a while, particularly with light blades.
 
1. Do a thorough engine warm-up before you spin up the rotors. Most people I have seen that do not do this end up flying with an engine that hasn't had a proper warm-up.

2. Get familiar with the "process" for your gyro. Practice the process several times before you try to actually start the rotors. For example, in the GyRonimo, it is necessary to climb up on the seat to reach the rotors and climb back down quickly, start the motor and move forward. This is no small task, but is mitigated by a set routine of foot and hand placement. Some machines require the motor to be running. Foot and hand placement, as well as a good wheel chock or brake routine is important for that process. Many machines require the stick to be held full forward to prevent a rotor strike or flap in wind. Make sure you have clearance with your head and helmet for your process. All of this needs to be worked out in advance.

3. Face the gyro into the wind. Starting the rotors with a crosswind could turn you over. Starting the rotors with a tailwind could be pointless, as the wind will be working against your efforts.

4. Start pushing the rotors slowly. This isn't a race at this point. Push each blade for the first few revolutions, then switch to every other blade once the speed comes up. Now it is a race. Timing is everything. The goal is to go "as fast as you can." If you have some wind helping, then you may quit as soon as you see the rotors coming up on their own. In fact, if you notice a rotor speed increase that you are not personally responsible for, you must stop, get seated and keep the stick at an appropriate angle.

5. The appropriate stick angle once seated depends on wind. If there is no wind, full back is generally required (though I tend to keep the rotor a smidge off the rear stop as it is easier to feel a coming flap that way). For wind that is keeping the rotors going for you or stronger, use the stick as a throttle. Forward to slow the rotors, back to speed them up. Of course, any sign of flap and move them full forward. Be careful not to let the rotors drag you backwards. You may not have sufficient braking to stop this with wheel brakes. Just push the stick forward to stop any tendency to go into reverse. Operating a gyro in reverse with the rotors spinning is an accident waiting to happen.

6. Begin moving forward. If your rotors have not started spinning up yet on their own, because you aren't getting any help from the wind, then move slowly. Your first goal is to move forward enough that you don't lose any RRPM you just worked so hard to create. The best way to lose it is to move too fast and cause a blade flap. A low speed, no wind blade flap "probably" won't flip you over, but it could. It could also certainly bend things up, and on some machines cause the rotor to strike the tail, causing a really bad day. So, once you are sure you are moving forward with a gentle breeze in your face, and are sure the rotors aren't slowing down. Add a bit more power. Just a bit. If the rotors start moving faster, you've got it. Repeat the process of adding just a tad more power until you get 80-100 RRPM. If at any time you feel the least hint of a flap, reduce the power and push the stick forward immediately. If you catch it in time, you can generally recover and continue, otherwise it is generally best to stop the machine and start over from scratch.

In all cases it is best to make your first tries in the presents and under the supervision of someone who knows the machine and has done this before, such as a CFI. This is not only for the purpose of getting the rotors spinning by the most practical and efficient methods, but for safety. I'll be the first one to say it is possible to get rotors up and flying while making a host of safety blunders that, but for blind, dumb, luck, could have ended badly.

That said...mechanical pre-rotators are a good thing!!! :D
 
Great post Jon.
 
Thank you Jon that was both very educational and informative. Damn we need to put stuff like that into some learning DVD or something like that. I am sure we could get guys with a wealth of knowledge make something educational that could be distributed maybe through PRA or local chapters.....
 
not for the novice

not for the novice

I must stress that hand-starting rotors is not for the novice. And since the original post was looking for the correct process to do this we must assume that he does NOT have any experience with it.

While I do agree that the process as defined by John is a good starting point and describes the process well. However, and I can't stress this enough,

BEFORE YOU EVEN THINK OF TRYING TO START A ROTOR, YOU BETTER HAVE ENOUGH EXPERIENCE TO BE READY TO FLY THE GYRO IF IT SHOULD GET AIRBORNE DURING THE PROCESS.

There have been too many accidents and injuries from people just wanting to "get the feel" of the rotor and it ends up costing major money and in some cased severe injury.

DON'T TRY THIS UNTIL YOU ARE READY TO FLY THE GYRO, BECAUSE ONCE THE ROTORS COME UP TO SPEED, YOU ARE FLYING!!!!
 
Thanks for your insight jon, I like how you explained using the stick as a throttle in the wind, this makes sence to me! Lots of good reading on this board!

1. Do a thorough engine warm-up before you spin up the rotors. Most people I have seen that do not do this end up flying with an engine that hasn't had a proper warm-up.

2. Get familiar with the "process" for your gyro. Practice the process several times before you try to actually start the rotors. For example, in the GyRonimo, it is necessary to climb up on the seat to reach the rotors and climb back down quickly, start the motor and move forward. This is no small task, but is mitigated by a set routine of foot and hand placement. Some machines require the motor to be running. Foot and hand placement, as well as a good wheel chock or brake routine is important for that process. Many machines require the stick to be held full forward to prevent a rotor strike or flap in wind. Make sure you have clearance with your head and helmet for your process. All of this needs to be worked out in advance.

3. Face the gyro into the wind. Starting the rotors with a crosswind could turn you over. Starting the rotors with a tailwind could be pointless, as the wind will be working against your efforts.

4. Start pushing the rotors slowly. This isn't a race at this point. Push each blade for the first few revolutions, then switch to every other blade once the speed comes up. Now it is a race. Timing is everything. The goal is to go "as fast as you can." If you have some wind helping, then you may quit as soon as you see the rotors coming up on their own. In fact, if you notice a rotor speed increase that you are not personally responsible for, you must stop, get seated and keep the stick at an appropriate angle.

5. The appropriate stick angle once seated depends on wind. If there is no wind, full back is generally required (though I tend to keep the rotor a smidge off the rear stop as it is easier to feel a coming flap that way). For wind that is keeping the rotors going for you or stronger, use the stick as a throttle. Forward to slow the rotors, back to speed them up. Of course, any sign of flap and move them full forward. Be careful not to let the rotors drag you backwards. You may not have sufficient braking to stop this with wheel brakes. Just push the stick forward to stop any tendency to go into reverse. Operating a gyro in reverse with the rotors spinning is an accident waiting to happen.

6. Begin moving forward. If your rotors have not started spinning up yet on their own, because you aren't getting any help from the wind, then move slowly. Your first goal is to move forward enough that you don't lose any RRPM you just worked so hard to create. The best way to lose it is to move too fast and cause a blade flap. A low speed, no wind blade flap "probably" won't flip you over, but it could. It could also certainly bend things up, and on some machines cause the rotor to strike the tail, causing a really bad day. So, once you are sure you are moving forward with a gentle breeze in your face, and are sure the rotors aren't slowing down. Add a bit more power. Just a bit. If the rotors start moving faster, you've got it. Repeat the process of adding just a tad more power until you get 80-100 RRPM. If at any time you feel the least hint of a flap, reduce the power and push the stick forward immediately. If you catch it in time, you can generally recover and continue, otherwise it is generally best to stop the machine and start over from scratch.

In all cases it is best to make your first tries in the presents and under the supervision of someone who knows the machine and has done this before, such as a CFI. This is not only for the purpose of getting the rotors spinning by the most practical and efficient methods, but for safety. I'll be the first one to say it is possible to get rotors up and flying while making a host of safety blunders that, but for blind, dumb, luck, could have ended badly.

That said...mechanical pre-rotators are a good thing!!! :D
 
If any of you have seen the show "timewarp" on discovery, I think it would be neat learning experience to see a rotor that was flapped in slow motion! Does anyone have video of a gyro that flapped its blades?
 
hand starting rotors

with a bensen type machine with a mac and the short mast I never saw a reason to carry the extra weight of a prerotator because I could reach the hub while sitting in the seat and with no wind and the engine at idle and the rotor full back I would push until it was turning as fast as it would go, then open the throttle a little and keep pushing as airspeed and rotor rpm increases, in about 200 ft the rpm will be faster than I can push, full rpm will be reached in about 5 or 600 ft. If there is no wind the rotor is left full back and airspeed is smoothly increased as rpm builds, any other method will work but will result in a longer ground run. If your machine has a longer mast then starting must be done while standing and it is best to have some type of spin up devise ,even a recoil starter will work.
 
I know that when the rotors are turn up about 100 it does not take long to get up to flight speed if have a good head wind.....
 
The starbee recoil prerotor seems like a good thing for someone trying to make weight, seems kinda pricey tho! :twitch:
 
I like the starbee recoil starter too. I have never used it, but it looks light and effective.

Worth the money if it works as suggested. Anyone have one of those? I'd like to know personal experience.
 
The StarBee recoil prerotator works well and is much safer than handstarting. With Sportcopter blades in 10 knots or more it's really easy and safe to get the blades spinning. In less than 5 knots it's hard work, the big advantage is that with some practice you can keep on pumping while taxing which gets the blades up to speed much quicker.

The contraption needs to be treated with care though, there is a pin that is a press fit and it likes to come loose and fall out after about 25 hours. A spot weld fixes that problem. And you need to take your time, if you get too aggressive the cable ends up where it's not supposed to be, and that means going back to start.
 
about 15 years ago, with my first gyro. A Mac powered Benson, with benson blades. While learning this process, I repeatedly would get a blade flap, most of the time I would see it coming and could stop the flap which had just started, EVEN USING A PRE-ROTATOR, and being conservative I would not spin up fast enough, before I would feed the air to the rotors.
Once in about a 15 - 20 knot wind - straight down the runway, I decided to try to fly the gyro.(1st error) I taxied to the end of the runway, turned into the wind, stick forward, a little prerotor. (2nd error) pulled the stick off the stop ( almost all the way back), and started a slow roll for takeoff. I was indicating about 25 mph, and did not allow the rotor to come up to speed. The FLAP which started was VERY VIOLENT, as the main landing gear tires were coming off the ground, bouncing from left side to right side. (I do not remember how many times I bounced from left side to right side, before I was able to arrest the Flap.
I was verrrrrry fortunate that I did not damage the gyro, or myself.
I would make the recomendation to all CFI's and ALL MORE EXPERINCED pilots (the rest of us) teach this to all newcomers. They need to recognize a Flap starting, how to arrest it, and then make the proper choice as to fly, or return to the Hangar and do a thorough inspection of the entire control system and airframe.
If you ever experience a severe flap of your blades, you will NEVER want to do that again.
 
When researching the Gizmo was told it would not get rotors much past 60 rrpm with a stationary gyro in no wind. Since I had been told DW's needed a lot more than that stopped considering it.

Love the electric one we got from Nicolas.
 
Resazi, I hand-started the 28-foot Dragon Wings on my old tandem Dominator a couple of times, but it was not pleasant. You have to "catch" them just right at low RRPM or they will simply flap and not accelerate. A light breeze is a big help.

DWs go into flapping very suddenly -- unlike more conventional blades, which usually give a couple of light taps before entering full-on, wrist-spraining stick gyrations.
 
IT NOT A FUN THING!
I can say I got my first taste of the light blade flap last week. the wind was behind me and I started to bring in the slow start prerotator when the blade started going side ways on me. I grabbed the controls with both hands and pushed it hard FWD into the rotor brake. this stopped the blades in 3 or 4 turns.. Thank god for that. After that when I got to that point again I had the blades turning about 70 or 80 RPM which did the trick.... No more blade flap.....
 
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