OK Collective - help me here.
I've been checking blade tracking forever but I don't recall seeing this phenomenon before. I have it with my home made grips and my entirely stock stuff.
Spin the upper rotor to enough rpm to feel some lift and look at the tracking. Mine is good but not perfect. If I slowly increase throttle the blades are tracking perfectly during the rpm increase. When I stabilize the rpm at the higher rpm, I see just a little tracking error again. I run rpm of both blades to the point where the heli is certainly lifting - if I let go the heli will fly away.
BUT - when I decrease throttle the blades loose anything that even resembles good tracking. The error is perhaps 3/8" at the tips during deceleration. When the rpm stabilizes at the lower rpm the blades settle again. I thought that it was my grips, but I get the same phenom with new balanced blades.

What's that about? Is mine the only one?
And what does that do to the fight dynamics? I know that when my blade tracking is off by that amount the heli shakes and has virtually no lift. Lift loss has to be a huge factor in flight as we try to decelerate for a landing. It seems to me that the loss of lift is disproportionate to the rpm change when I come in from the yard to the patio where I land. I thought it was air washing over the house and pushing the heli down. Now I'm not so sure.

thoughts?
Soloboss

try the throttle trim trick - throttling back to 0 is similar to you shutting off your car engine to slow down, power steering goes, power brakes go, nothing works right, etc - throttling the car back to idle just slows down and everything keeps working

i use the "start" method now - Stop Throttle And Resort to Trim lol - spin up with throttle trim (wow, that's just like a real heli), fly around with the throttle (behaves more like collective), spin down with throttle trim when completely done - keeps the head speed up and the heli stable and in control

i'll try it in a minute here and check the tracking on my cx's

must remember to chop both if crash


edge

The flutter that I see happens when I decrease throttle gently from 'lift' rpm down somewhat. I'm not chopping the throttle to zero to see the effect. That's what concerns me. Any decrease in throttle flutters the blades.
I hope it's just mine because this isn't a problem we need. And if it is just mine, I have no idea what to do about it.

This is an aerodynamic occurance, there is nothing wrong with it and nothing you can do about it. When blades are tracked on a real Helo, they are typically tracked at a hover, once IGE and once HOGE, they are tracked again at various speeds... in the case of the CH-47, they are tracked at (if I remember right) 60Kts, 90kts, 120kts, and 140kts. The key is to get the tracking to the best possible tracking for the flying you will do. Now in the case of rc, I would suggest (still new to RC) that you simply track it the best you can.

I like the idea of using the throttle trim with the throttle. I did that for a while some time back and I liked the response, but I just knew that it was going to cost me a 4 in1.

Since the trim pot is just changing the location (range) of the throttle I can't get rid of the trim pot and just use the throttle. And like you, I like the idea of spinning up the rig using the trim, then flying using throttle. That's cool.
BUT I can see myself trashing a 4 in 1. We need one of our wizards to give us the mod to take the throttle circuit to minimum. Maybe a kill switch? Something that will supersede the trim and let us kill the throttle in the event of a crash. If we open the throttle circuit, will the heli go crazy from the lack of signal?
Does this warrant a new post so we can get all of the thoughts on a clean sheet?
Soloboss

Solo, mine doesn't do that phenomenom; for whatever reason; maybe it's the XTREME blades. If I'm reading this correctly, then the blades are so loose in the grips that the forward resistance is outweighing the centrifigal force to keep them in alignment at slower rpm's and they push back some out of alignment and flutter. At the higher rpm's, they track correctly with much more centrifigal force. That's just my opinion. You might try adding a tiny bit of weight at the tips, such as tracking tape for decoration.

You can temporarily get them aligned, tighten them and see if the flutter goes away. This would test my theory.

Gary

I'm getting the flutter from my stock blades (no grips - rigid mount like from the factory) also. I was hoping that it was my grips.
From reading the post from chilei, it's normal. I guess I never noticed it before.

You'd think that I'd recall that from trimming my CH-47. I do that in the back yard where it's grassy so if I fall off the heli I don't get hurt. My neighbors hate that CH-47 in the back yard because of the noise and the mess is makes, but it sure blows the leaves out of the neighborhood. Unfortunately it also blows the water out of the neighbors pools. Har Har Har

So it sounds like you have a story to tell, chilei. What's up with that? And if you are watching the CX forum, are you a new flier?
Curious minds need to know.
And we are always looking for new victims for our Collective.

Soloboss

Perhaps it's the stiffness of the Xtreme blades. That would make sense. The flutter may just be flex in our flexy blades.
I just looked at the Xtreme grips on Michael's site (ushobbysupply.com). No wonder you are a fan. That's a really good looking piece. Makes my home made stuff look cheap. I'll paint my home made setup. That'll fix the look.

Yea, might be; or I just don't notice it. I'll look closer, but I need good straight shafts and I haven't had that for awhile.

On the XTREMES, they have the airfoil right to the tips, (explains the good lift) so they always looks like they are not tracking, but what You are really seeing is the depth of the blade; it isn't like the stocks where they feather to almost flat.

What I look for is deviation up and down motion; if I don't see that, then I know it's good.

Something else I noticed; If I'm balancing two blades that differ greatly in weight, (numbers don't match) then i try to put the weight on the C.G. of the blade and not at the tips, cause that causes some fluttering as well. I got that tip from a thread I started not too long ago about how to balance blades. I also don't layer the tape; I put a slender rectangular piece of clear packing tape running with the blade, not perpendicular to it on the underneath side with the center at approx. the C/G of the blade. If it is still too light, I cut carefully a square piece of that, lift it up and move it to the outside of the blade. This balances the blade without having to add any more tape or layering it. If it's heavy after doing that, then I lift up the small piece again and move it towards the hub more.

So, I'm distributing the weight as it needs to be with most of the weight at the C/G

I have had similar problems with blades...just crash it and put on a new set and it goes away To be serious I think it's the blades change them out and it should go away.

Soloboss, I have flown CH-47's, UH-1 Hueys, and HH-65 Dolphins, been flying real aircraft since 1990. As far as RC's, I have only been flying them for two weeks. I have a Blade CP pro, hover it in my back yard, but my definition of hovering the RC is nothing like my definition of hovering the other aircraft!!!! heheh, I'd like to think the definitions will come together shortly!

BTW... I enjoyed your comment on trimming your CH-47 in the backyard, very creative! I am new in the forum and have been enjoying it a great deal!

I'm thinking that if you "hovered" the Huey like you (probably) hover the BCPP, all of your passengers would be wearing barf bags! Taking on the CPP is quite an undertaking. I started with the CP and decided that the cost to keep myself in the air would be monumental. So I sold it and went with the Blade CX. Yeah, I know - it's coaxial. But the movement is much closer to the movement of a scale / real heli. I also have a Falcon 40 single rotor, fixed pitch so I can learn to fly a single rotor heli. I'm gaining on that one slowly and I don't practice anywhere near enough to get good. The advantage of the Falcon (or EF Sabre or Walkera #4) is that I need only straighten the blades on the hub following a rough landing. With the collective pitch helis there is typically more alignment required. I need to fly - straighten - fly again to get my practice time in. I do see a larger collective pitch in my future, but it's still a long way out there.

If I were one of the lucky few who have natural eye hand coordination and take naturally to the helicopter flight dynamics, I would be into a more sophisticated machine. But with that, I would have bypassed the little coaxial helis and that would be a loss as I have become really attached to my CX. It's great indoors and even outside in calm weather. IF you follow the CX / CX2 threads you'll find a dedicated group that's always up to something resourceful and creative. We tend not to take things too seriously, but that statement is not supported by our (empty) bank accounts.

If you are into anything resembling a hover in two weeks with a collective pitch heli, all I can say is WELL DONE, my friend.
With this post you are making a lot of 'fliers' jealous. Many have the desire to fly a real heli, but we know that it's not happening. Not in this lifetime.
So the RC world becomes our reality and it does truly take on a life of its own. It's a great pastime and this forum is a gathering place an amazingly diverse group of people.

Welcome aboard and get comfortable. This is a great place to loose hours of your life.

Thanks a lot solo! I am far from satisfied with my hover but can keep the aircraft in a 20X20 area. I believe I was helped by my knowlege that no helicopter requires much input at all and that simply muscling it around does not work, you truely have to nudge it where you want it. I went with the CP Pro because I like the challenge and like the thought that if I learn on a hard one, I will be less damaging on a bigger and more expensive helo. May be flawed logic but I am going with it! My CPP has the Bell-Hiller upgrade as well (bought used... with a lot of parts).

I know that many want to fly the real thing, I was very fortunate, the Army paid for my flight training and the first 1, 400 hours of Huey and Chinook time, the USCG paid for the 2,000 hours of HH-65 time. And yes, when learining the Huey, I remember looking at the tower through the greenhouse on more than one occasion. But rest assured, while I was flying 0 scale aircraft, I always wanted to get into RC helos, only weeks ago did I decide what the hell and did it!

Thanks for the welcome! I am busy finding information here, and can offer no RC advice specific but can certainly offer information as it translates from 0scale helos and aerodynamics.

I have already been eyeing other helos in my trips to the "parts dept" of my hobby store!

Hey Chilei, so is flying a real helicopter harder or keeping the CP Pro in a hover more difficult? : ) All consequences (death!) and responsibilities aside of flying a real aircraft, the way our RC helis are designed, does it require completely different stick movements compared to your old rides?

- K

I don't want to miss the opportunity to thank you for your contribution to the defense of this fine country. Through the efforts of yourself and thousands more like you, we can keep playing with our toys - ummm - pursuing our hobbies.
And yeah, we're a bit jealous of your 'pastime'.

Thank you!

In my couple of weeks, I have found that they handle very much like a real helo... I found myself several times with mine and thinking that I know what it looks like from the inside. I have found that there are some differences. 1. I am used to feeling the sensation and noting very minute change and I can not pick up on that as fast (I have to see the attitude of the helo and the relative movement) 2. I have the benefit of knowing that a very small input gets the change going and an opposite input removes said input, so I may be at an advantage with having that knowlege from the start as opposed to getting it later. I never expected it to be easy or to be big motions (killing snakes, or stiring the pot as we used to refer to it). 3. not having guages for altitude and specific heading, or attitude for that matter is a bit more difficult.

My initial thoughts are that someone going from RCs would have a bit easier time learning real helos due to the control touch than someone going the other way... it is very difficult to control it from the outside.

Incidently, my wife was looking through my RC Helo mag and noted the simulator, asked why I didn't have one instead of spending hours fixing it... about an hour later we were at the hobby shop getting one. The Realflight sim works great but I was told I could download the other aircraft and then found out that the blade model is based on an aircraft which I have to get in an expansion pack. I plan on getting it, but have been using one of the other models. After hovering it for a few hours on the sim, I flew mine with great results!! Anyone learning should get a sim... I have noted a huge change.

Soloboss, thanks for the sentiment, I have always loved my service (Army and USCG) and have been lucky to be able to do what I love. With that in mind though, there are many who are making far greater sacrifices than I... for those, I will join you in a heartfelt thanks!

Welcome! I used to be in the Navy, last stationed in Norfolk. Lived in Hampton, near the AFB. I would have liked Norfolk if I would have ever been there! I was on an attack sub and we were out to sea like 85% of the time. You wonder why I got out...

Sweet! I am in VA beach. Like the Sub mission, read a great book I know you have heard of... Blindman's Bluff... great read!

Simulators are great, aren't they? I wasn't a sim user until I got the single rotor heli. I was having a lot of trouble and my problem was so repeatable that it was predictable. That is frequently a sign of heli problems - either setup or a real problem. Then I got the sim and the sim helis are set up perfectly. But my problem on the sim was the same as in RC flight. Exactly the same. And you know what that means. The problem was the stupid human at the helm. So I am able to work on my skills and save repair costs. Lucky my.

For a real pilot a single rotor heli may work well for you. The mechanics of a coaxial have you controlling the servos and the servos directly control the lower rotor via the swash plate. And whatever you do is negated by the upper rotor / flybar. So as you said, you need to see the heli move to be able to know what it's doing.
On the other hand, a single rotor has the servos running the blades directly, but the flybar is in the equation to slow the response of the input. The neat thing about the flybar is the paddles on the flybar will "plate" at flight rpm. You will know what the heli is about to do by watching the flybar plate. When it moves, you can correct it before the heli moves. And you fly by watching the plate - add control and return the stick to center, watch the plate and correct as required. It's not like feeling the heli, but it does give you a reference that moves prior to the heli movement.
Just thoughts.

Soloboss,

I tried a greater concentration of weight at the tip of the flybar, instead of the spread of 3 collars length, I put a slightly heavier 'bullet' shaped weight off another flybar mod. and the slight flutter I noticed after reading Your post, all but dissappeared ! Runs much more truer now; I don't know why, but I sure like it now ! ! The heli will sit stationary on a glass coffee table, and won't creep, even at near takeoff speeds.

When the weight is distributed over a greater distance, that's when I get the 'shivers' to more or less degree. You might experiment and see.

Gary

That's worth a look. Thanks Gary.

lol if you put lead weights on your heli do you have to include a sticker for california saying it may cause cancer?

we got something the other day that had lead warning stickers all over it


edge