Originally Posted by chadandrews

Thanks Steve!!! For the compliments and videos!!! Would you look at that, very nice. I am familiar with the full lotas floats, having built 4 homebuilt aircraft thats what we used on them. Ahhhh Look closely at the sport copter video, full left rudder during prerotation and a set of water rudders....So cool. yep thats in the future design for sure. Neat how they are the full length of the gyro...I bet my carbon z cub floats would do the trick.

Agreed! The water rudders made the difference. It would be interesting to see how well that translates to the modeling side of things. I'm a bit familiar with the Sportcopters design. The prerotation system on their gyros use a friction wheel rubbing against the prop hub. The pilot can engage that as softly as he needs to. I'd imagine he wasn't pushing the prerotator as hard as he could have been. I obviously don't know that for certain but it would make sense. Of course on the model gyros like yours, that use an electric prerotation system, you don't have that option. It's basically all or nothing.

That brings me to a question. How do you have the prerotator programmed in your radio system? Are you using a switch, or some kind of proportional slider control on the radio? Is the ESC programmed as an airplane or helicopter with soft start? For now, I've got a Castle Creations ESC programmed as an airplane with the response parameters set as slow as possible. I also found a setting in my radio that slows down the rate at which a servo would move when the control is activated. All of this is assigned to a switch. Watching the servo graph in the transmitter, if I was using full throws (which I'm not), it would take 45 to 50 seconds to move from one extreme to the other. I've played with it with the rotor hub removed. It'll be a while before I take it outside and try it with the rotor hub installed. It might be too fast even at that. In which case, I can assign the control to a slider that I move directly. I'm just curious to know how you set yours up.

Fly Safe,
Steve R.

Hi Steve,

The prerotator is programmed in the radio for 12 second servo rate from -100 to +100, or is 0 to +100. One of them, I have it on the "trainer" button on my DX9, so I press it and it starts up nice and slow and then takes 12 seconds to reach full speed. The top speed can be adjusted by lowering the +100%. But a properly chosen motor / gear combo should yield 100%. I choose the trainer button because it is a momentary switch. No danger of leaving it on by accident. Also, with the model gyro, as opposed to the large one, we can control the torque, with the momentary switch and the 12 second delay, I have plenty of time to release the button if the torque is too high and just press it again to maintain. Make sense?

Originally Posted by chadandrews

Hi Steve,

The prerotator is programmed in the radio for 12 second servo rate from -100 to +100, or is 0 to +100. One of them, I have it on the "trainer" button on my DX9, so I press it and it starts up nice and slow and then takes 12 seconds to reach full speed. The top speed can be adjusted by lowering the +100%. But a properly chosen motor / gear combo should yield 100%. I choose the trainer button because it is a momentary switch. No danger of leaving it on by accident. Also, with the model gyro, as opposed to the large one, we can control the torque, with the momentary switch and the 12 second delay, I have plenty of time to release the button if the torque is too high and just press it again to maintain. Make sense?

That does make sense, thanks. I guess one of the things I was considering was the weight of the rotor system and the stress on the prerotation gears which seem "very" small and light for this application. Not having any experience with this aspect of the model, I was concerned about trying to speed the rotor system up too quickly and stripping gears as the rotor system on the GyrOne is quite heavy, much more so than any model helicopter I've owned.

The switch I chose is one I've never really used before in any other application and it's one that I don't naturally make contact with in any other situation so I'm not too worried about accidental activation. Since I was slowing the travel rates down so slow, almost four times slower than what you're doing if I'm understanding all this correctly, I chose to not use the momentary switch. Considering what you just said though, I think I'll probably swap back to the momentary switch anyway. It really does make sense and there's always that first time of hitting a switch unintentionally. In this case, that could definitely cost me the model. Better safe than sorry.

Now, when you mention achieving 100% prerotation, are you just talking 100% in the radio, or 100% of your target rpms on the rotor system? In my case, since I wound up with a higher Kv motor than recommended, I doubt I'll get to 100% in the radio. That's Ok with me as long as it works. I suppose if everything is setup correctly, they should be one and the same but from what I've seen in the experimental full size versions, prerotation rpms rarely approached 100% in-flight rpms. If the model will approach 100% in-flight rpms, I think that would be great. Seems like it would greatly reduce the chance of roll over on take-off from too slow an rpm. Thanks for all the feedback, this is helping a lot!

Fly Safe,
Steve R.

Hi Steve,

I was referring too 100% on the radio, with correlation to a properly setup motor. So yeah, it would be 100% of the rotor rpm as well. Mine actually exceeds flight rpm a tad But Woody can literally take off in two feet!! One odd thing I did notice, is that in a no wind condition with the gyro stationary I get blade flap at max prerotation. if the gyro is moving forward or there is a little breeze the flap is completely gone. I suspect it has something to do with the rotor being turned artificially vs. the relative wind pushing it as it is designed to do, forces on the blade and all that good stuff. But whatever way i have it setup, i have zero complaints, it really works well. Guess I got lucky on my 45th try hahaha

Originally Posted by chadandrews

Hi Steve,

But whatever way i have it setup, i have zero complaints, it really works well. Guess I got lucky on my 45th try hahaha

Well, with your help and others, I'm hoping to get there a little faster than that but I understand there's a learning curve and one way or the other with RC aircraft, there is always dues to pay!

I gotta get that trainer up and running first. I hope to get that started next month. Then the real fun/frustration(?) begins.

Fly Safe,
Steve R.

The norm is for the pre rotator to be either on a slider switch, or rotary or 3 position switch. With Futaba high end radio so probably others too it is possible to put mixes in that prevent the rotator working.
You won't need a pre rotator on the Whippit for example, just the correct shim to give negative attack on the blade.
Here is my latest Whippit for the 2016 Gyro meets.



This is the first one I built, it flies a dream, ROG hands off.

Originally Posted by BigTradioman

The norm is for the pre rotator to be either on a slider switch, or rotary or 3 position switch. With Futaba high end radio so probably others too it is possible to put mixes in that prevent the rotator working.
You won't need a pre rotator on the Whippit for example, just the correct shim to give negative attack on the blade.

Thanks Tim. I considered a slider too. I've got them on either side of my radio. The rotary knobs are top center of the transmitter and would require taking one hand or the other off the controls to operate and I don't like that idea in this case. I'll play around with the different configurations and try to decide which I prefer.

On the shimming issue. You've used that word before. The instructions I have with my GyrOne don't mention anything about that. I understand what you're getting at, setting the pitch incidence of the rotor blades to an angle that maximizes the efficiency of the autorotation. What I'm curious about is, how do you set that? I understand you're putting shims under the blades to change their angle relative to the hub plate but, do you actually measure the blade angles, or experiment with it until it's working like you want it to, or a combination of both? What angle of incidence are you usually aiming for? I've seen a number of videos where the model is simply held up in the wind and they seem to spool right up. The pilot would be able to feel the lift/pull being generated by the rotor system as it gains rpms and, I'd think, that would give them a good idea as to whether or not the model is ready for flight.

Thanks for the input!

Fly Safe,
Steve R.

Hi Steve,

I'll jump in on the shimming. Your exactly right in your thinking, it's negative blade angle (well lets call it that) or how the blade looks in relation to the rotor shaft. Tipping it down in the leading edge (or up in the tail) will cause it to windmill more easily but reduces lift. Its a delicate balance to get the amount of lift you need, and a nice blade spin up. This is most evident on smaller models that have lots of blade lifting force but need rpm to get the blades into auto-rotation. You'll find as the model gets more heavy and larger the blade angle is less. You will also find that most start using pre-rotators on the larger models because they are difficult to get the blades started by windmilling. On my model I have no shim at all and the blade appears flat to the hub. I can give mine a hand flip and roll down the strip but the roll out will be long to get the blades up to speed.

Chad

Originally Posted by chadandrews

Hi Steve,

I'll jump in on the shimming. Your exactly right in your thinking, it's negative blade angle (well lets call it that) or how the blade looks in relation to the rotor shaft. Tipping it down in the leading edge (or up in the tail) will cause it to windmill more easily but reduces lift. Its a delicate balance to get the amount of lift you need, and a nice blade spin up. This is most evident on smaller models that have lots of blade lifting force but need rpm to get the blades into auto-rotation. You'll find as the model gets more heavy and larger the blade angle is less. You will also find that most start using pre-rotators on the larger models because they are difficult to get the blades started by windmilling. On my model I have no shim at all and the blade appears flat to the hub. I can give mine a hand flip and roll down the strip but the roll out will be long to get the blades up to speed.

Chad

Thanks Chad, that's kind of what I was thinking. I've flown helicopters from the very start of my RC hobby experience and the first thing I started learning to do after I got comfortable with forward flight, was autorotations. Through the years, as I've gotten more comfortable with it, I've played around with autos and experimented with how the model responded to various situations and collective settings. It's been a slow process that depended heavily on the prevailing conditions at the field that day and how brave I was feeling too! What I've found generally is, with most of my models I end up with the collective between -1 and -2 degrees incidence in a steady state autorotation. How did I figure that out? I've had friends some out and note the position of the control stick once I was happy that the autorotation was established and stable. Then we'd simply go back to the table, put the pitch gauge on a blade and check the incidence with control stick in the noted position. That -1 to -2 setting has been fairly consistent through a number of models I've owned from, to use today's vernacular, 550 size birds all the way up to an 800 class Bergen gasser I'm currently flying. That Bergen, by the way, is the easiest autoing model helicopter I've ever owned, in spite of it's near 15 lb weight. I did have one day, many years ago with a 60 size Miniature Aircraft X-Cell when the conditions were about as perfect as they could be and I was feeling particularly confident. I was experimenting with seeing how slowly I could float the model down in an autorotation. The winds were unusually steady that day about something between 10 and 15 mph. The model was coming down very slowly, almost just sitting there, and I'd have "just" enough inertia left over to cushion the touchdown for landing. Finally a guy walked out and asked what collective setting I was autoing at. Of course, I had no idea what that was so I had him watch the stick position while I did another auto. When we put the model on the table and positioned the control on the transmitter. It turned out that the model was autoing down at a blade incidence of just a hairs width over +1 degrees incidence. Until that day, I wouldn't have believed a model helicopter would auto with the collective setting in positive numbers. Mind you, the conditions were perfect and the rotor was turning so slow I could almost count the blades, but it worked.

I'm going to order the Scout trainer after the first of the month. I'm looking forward to experimenting around with that aspect of it's setup. On the GyrOne, it's a pretty good sized bird and based on what you just said, I think I can understand why they don't mention shimming the blades. I've got them mounted on the hub at the moment and they look like they're pretty much set at 0 degrees incidence and I imagine that's work out just fine. We'll see.

Thanks for the reply & Fly Safe,
Steve R.

Hi Steve,

Hats off on the heli flying, i had a go at it years ago and it was just too much going on for me to control it. Mind you it probably wasn't the best heli, Kyosho Nexus 30, but i found it very hard to control so i just stuck with fixed wing until i got bitten by the autogyro bug. Sounds liek a nice smooth auto on the bigger ship. I dunno, but it's been my experience the bigger the ship, the easier they are to control. Not sure if its visual or because they are bigger they don't dance around like the smaller stuff. I have always favored the larger.

Yep, play around with it is the best thing to do until you fully understand what effect each change has on what. In my earlier experiments I have always went with achieving the best lift which was a mistake. Most times it would head for the clouds in a vertical climb and sometime i would save it, most times not. Hahaha. Now I always start with more shim then I think is required, the blades spin up awesome, and if it doesn't lift off due to lack of lift, no big deal, no harm done. Lower the the shim amount and try again. At least this way I know I am getting the rpm i need to get rid of the deathly roll on take off and if it doesn't take off then it won't be damaged. The shims are pretty sensitive, and I mean the thickness of a piece of tape sensitive. I have literally gone from no take off to perfect test hop in the thickness of a piece of tape under the trailing edge. So it's worth some experimenting. Reading most of the post's here you will see a lot of people settle on the usual 0.8mm shim place a cm or so behind the blade bolt hole. It gives a good spin up and lift combo.

Hope this helps,

Chad

Originally Posted by chadandrews

Hi Steve,

Hats off on the heli flying, i had a go at it years ago and it was just too much going on for me to control it. Mind you it probably wasn't the best heli, Kyosho Nexus 30, but i found it very hard to control so i just stuck with fixed wing until i got bitten by the autogyro bug. Sounds liek a nice smooth auto on the bigger ship. I dunno, but it's been my experience the bigger the ship, the easier they are to control. Not sure if its visual or because they are bigger they don't dance around like the smaller stuff. I have always favored the larger.

Yep, play around with it is the best thing to do until you fully understand what effect each change has on what. In my earlier experiments I have always went with achieving the best lift which was a mistake. Most times it would head for the clouds in a vertical climb and sometime i would save it, most times not. Hahaha. Now I always start with more shim then I think is required, the blades spin up awesome, and if it doesn't lift off due to lack of lift, no big deal, no harm done. Lower the the shim amount and try again. At least this way I know I am getting the rpm i need to get rid of the deathly roll on take off and if it doesn't take off then it won't be damaged. The shims are pretty sensitive, and I mean the thickness of a piece of tape sensitive. I have literally gone from no take off to perfect test hop in the thickness of a piece of tape under the trailing edge. So it's worth some experimenting. Reading most of the post's here you will see a lot of people settle on the usual 0.8mm shim place a cm or so behind the blade bolt hole. It gives a good spin up and lift combo.

Hope this helps,

Chad

Thanks Chad, that helps a lot. When you say "tape," what kind of tape are you talking about? When you first mentioned the word, I was thinking scotch tape, like what you'd use to wrap a birthday present, or are you using something with a little more thickness?

Fly Safe,
Steve R.

We use electricians insulating tape or masking (painters) tape.

Originally Posted by BigTradioman

We use electricians insulating tape or masking (painters) tape.

Got it! Thanks Tim. Actually, I was thinking the scotch tape might be a little thin for the purpose but simply didn't know. I suppose it might depend on how much the pilot wants to "fine tune" things but the masking or electricians tape sounds good. I've got lots of that around the house!

Chad, PM sent!

Originally Posted by chadandrews

I done a little drawing for ya... Its just a strip to move it outwards to clear the channel. Small piece 1/8" AL should do the trick, on one of my heads I have it made from GF for a little more crash resistance, hahah

Hopefully we are all talking about the same thing

This is the information I have been searching for as well as all the other hints contained the thread.
I've been puzzling over how to implement the sacrificial bolt idea. The deep sides to the blade holder had me foxed I was thinking they must have ground away a lot of the tall sides.
Just need now to source some strong alloy sheet or thin bar.
I presume the bar/sheet would have to be quite thick since it has no sides to stiffen it? (I wonder if I could use a steel plate?)
Shame the blade holder is not the other way up then it would be stiff and it would be easy to just fit a plastic/nylon sacrificial bolt.

Just found this picture of a blade saver mod.

Is there a report on how the first flights went?