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Old Aug 30, 2012, 10:05 AM
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I thinks its a good idea as well. I map out my own helis vibe signature during setup by running up the heli with pinion disengaged from the main gear, then engaged with no blades, then tail blades and then mains.

This allows me to see exactly what object is related to each peak on the scale. It takes a little time, but works really well for me and I know exactly what each vibe peak is connected to.
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Old Sep 01, 2012, 02:18 AM
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that's a great idea and hopefully once the ball gets rolling others can through into the pot of vibe tracking knowledge.
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Old Sep 01, 2012, 07:01 AM
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that's a great idea and hopefully once the ball gets rolling others can through into the pot of vibe tracking knowledge.
Yeah, it really helped to me to learn what was coming from what. I can just glance now and know exactly what part the peaks are coming from without even knowing the associated RPMs.

Where I am weak is if the peaks are coming from sources other than the main spinning parts such as bearings.. I could also really use help when it comes to "up and down" vs "side to side" vibes, so I think we could all benefit from a vibe database of some sort
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Old Sep 01, 2012, 03:37 PM
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Yeah it takes some expertise (or in my case blind luck?) to spot bearing issues and harmonics. You really have to get your head inside the heli for those things. I remember spotting a cracked bearing race in a fairly well known builders heli last year. I warned him and within two flights it failed. He was astonished. This is my only reserve about stuffing my new 540 into a heli. The vibe logging feature the Sk720 and now the newer black edition has is priceless. It has throroughly spoiled me and is the mainstay of my heli diagnostics now. So flying the 540 without this is kind of a downer for me.
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Old Sep 01, 2012, 07:31 PM
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Starting to doubt my skills

Well I finally got my second Pro built and attempted to do a test over today, but had a slight mishap. I tell you, I have been flying for a few years now and I have never had as much trouble getting a heli back in the air as I have lately. I smashed a brand new Pro during its maiden a few months back due to the logging bug (my error for not having the proper fail safe set.) Now today I go to spool up and I accidentally bumped the rudder just a tiny bit right before lift off and the heli did a 360 on me before I knew what happened. I managed to hit TH before it rolled onto its side and the only damage is a stripped umbrella gear and the tail case was twisted out of the key hole on the boom.

It's an easy fix, but damn I'm starting to get gun shy here! I have moved the rudder with a heli spooled up sitting on the ground before, and have never had one spin on me like this. At first I thought something was wrong with the tail setup, but it's perfect and the gyro is correcting just as it should. I have been over every aspect of this build 10 times to make sure it was set up perfectly before maiden.

My guess is the unit saw the rudder blip and because I was sitting on my landing pad with rubber skid stops, the heli didn't move so the gyro sent the tail full bore until the heli broke loose and spun. A least I hope that all the issue is. I'm going to mount up on a swivel test stand just to make sure for the next try.

The good thing is I had killer low vibes on the short spool up. Less than .02 on the actual scale with no identifiable vibe peaks at all. The PC software said "0.0" when I asked to view the last vibe reading. This is pretty good considering the heli was on the ground where vibes are amplified back up into the heli more than what happens in the air.
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Old Sep 01, 2012, 08:57 PM
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one of these days they might have software that will just tell you where to look like "check tail shaft bearings", wouldn't that be cool !!!
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Old Sep 01, 2012, 09:25 PM
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one of these days they might have software that will just tell you where to look like "check tail shaft bearings", wouldn't that be cool !!!
It could be like the check engine lights on cars
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Old Sep 02, 2012, 02:06 AM
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Interesting you would say that. Georgi over at HF found a systematic vibe analysis program from a company that does this for upper end mechanical factories. It breaks down everything! In greater detail than anything I have ever seen. Really, down to fine details, stuff like seeing running bearing harmonics that can even spot one nicked ball in a bearing case and pinpoint which stator is slightly off in your motor winds.. They use the same accellerometers Art uses in the Sk720. He was trying to get Art to integrate this into our vibe analysis software. I have never seen Georgi so frustrated as he was when this didn't take off. It was and is a brilliant program. I don't know the financial details of it though and am sure that had alot to do with things.
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Old Sep 02, 2012, 08:58 AM
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i'm mildly impathic but shhhh don't tell anyone, ok ?
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Old Sep 02, 2012, 12:41 PM
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Guys:

I have read many instances of FBL heli's coming unglued and spinning, tipping, or doing a rainbow on takeoff and for the life of me, I can't get that out of any of my 3 axis controlled helicopters. The latest two helicopters for me are my Jet Ranger and my Ecureuil AS350, both of which have SK720's in them and I have never had these two heli's want to swap ends or orientation on takeoff.

In order to fly both of these helicopters in a very scale fashion, the takeoff is the most critical because of the angle of the mast to the ground. Both must come up on their rear skid tips so that they takeoff vertically and this requires input to the swash and rudder while doing so. The rudder input is required to make sure the thrust is balanced so the tail does not swing and the cyclic input is required to level the rotor disk so that the heli lifts off straight.

It could be because I do not take off directly the second the rotor is up to speed but take the time to bring it to speed then slowly increase collective until the skids are just light enough to allow movement. My goal is to make it so that the heli rises off and does not move in any direction but up so it is a very challenging takeoff requirement to meet. Even when these helis were in fishhead condition, I did not spool up then jump them up to speed up the takeoff but took the time to make sure that they rose as straight as possible.

I have always had trim at initialization enabled and have left the auto Bell trim on. The general vibes I am getting from club members is that I am flying these two helicopters unlike they have ever seen before at our club. There are very, very few scale helicopters there and even the pilots that fly circles around my in 3D capability are amazed at how they look in the air, to which I give a lot of the credit to the stabilization systems installed and taking tips from F3C helicopter setups to get the firm, yet docile, cyclic action needed for scale.

My Jet Ranger was using V3.02 up to last night and my AS350 was running 3.12 from when it was available until last night. I will not be getting out to the club until tomorrow to try out 3.15 in both but I don't expect anything different in performance than what I have now. I am just trying to help understand why it is that so many have crashed before even coming off the ground when I am moving the cyclics and rudder before liftoff and not getting the tendencies for the heli's to want to dump like I have seen in many, many posts. Hope this helps and take care.

Don
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Old Sep 02, 2012, 02:35 PM
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Originally Posted by Keyrigger View Post
Guys:

I have read many instances of FBL heli's coming unglued and spinning, tipping, or doing a rainbow on takeoff and for the life of me, I can't get that out of any of my 3 axis controlled helicopters. The latest two helicopters for me are my Jet Ranger and my Ecureuil AS350, both of which have SK720's in them and I have never had these two heli's want to swap ends or orientation on takeoff.

In order to fly both of these helicopters in a very scale fashion, the takeoff is the most critical because of the angle of the mast to the ground. Both must come up on their rear skid tips so that they takeoff vertically and this requires input to the swash and rudder while doing so. The rudder input is required to make sure the thrust is balanced so the tail does not swing and the cyclic input is required to level the rotor disk so that the heli lifts off straight.

It could be because I do not take off directly the second the rotor is up to speed but take the time to bring it to speed then slowly increase collective until the skids are just light enough to allow movement. My goal is to make it so that the heli rises off and does not move in any direction but up so it is a very challenging takeoff requirement to meet. Even when these helis were in fishhead condition, I did not spool up then jump them up to speed up the takeoff but took the time to make sure that they rose as straight as possible.

I have always had trim at initialization enabled and have left the auto Bell trim on. The general vibes I am getting from club members is that I am flying these two helicopters unlike they have ever seen before at our club. There are very, very few scale helicopters there and even the pilots that fly circles around my in 3D capability are amazed at how they look in the air, to which I give a lot of the credit to the stabilization systems installed and taking tips from F3C helicopter setups to get the firm, yet docile, cyclic action needed for scale.

My Jet Ranger was using V3.02 up to last night and my AS350 was running 3.12 from when it was available until last night. I will not be getting out to the club until tomorrow to try out 3.15 in both but I don't expect anything different in performance than what I have now. I am just trying to help understand why it is that so many have crashed before even coming off the ground when I am moving the cyclics and rudder before liftoff and not getting the tendencies for the heli's to want to dump like I have seen in many, many posts. Hope this helps and take care.

Don
Thanks for that info Keyrigger. I'm stumped with my spin issue I had yesterday on maiden for the exact same reason.

I have owned and been flying with my SK720 since they first came out a few years ago. I have more trouble free flights than I can count. I have also bumped the rudder many times with my heli sitting on the ground fully spun up. Usually it's because the tail will kick around just a few inches on spool up, so I bump it back around to get the heli straight before taking off. Never been any issue doing this.

I, like you have also never had any issues at all with the heli trying to roll or tip during takeoff, or had the need to "pop" my heli into the air.

This is why I was so caught off guard yesterday when my new build was all spooled and ready to go, and the slightest touch of the rudder sent the heli into a CC spin as if I was holding full rudder doing a ground piro

I really, really hope this isn't something different now with the new software since that is one thing different from before. My gyro and tail is set exactly as it needs to be, so revered gyro isn't the issue.

I guess time will tell once I get a new tail gear in and can give it another go. I just want to get it flying so I can relax and stop clenching my butt every time I time I spool up waiting for something to happen. Two crashes in less than 2 minutes flight time is starting to get embarrassing for someone that has been flying five years now.
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Old Sep 02, 2012, 02:56 PM
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That sounds like you have the direction reversed in the tail gyro compensation. If you have it reversed, as soon as the tail becomes light and you even slightly hit the rudder, it will violently spin and can destroy a heli if you don't get the collective to plant the skids. I have had that happen to me twice in a row and it was entirely my fault in both instances as I did not properly check the tail compensation before spinning up. Take care.

Don
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Old Sep 02, 2012, 03:28 PM
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Originally Posted by Keyrigger View Post
That sounds like you have the direction reversed in the tail gyro compensation. If you have it reversed, as soon as the tail becomes light and you even slightly hit the rudder, it will violently spin and can destroy a heli if you don't get the collective to plant the skids. I have had that happen to me twice in a row and it was entirely my fault in both instances as I did not properly check the tail compensation before spinning up. Take care.

Don
Thanks Don and that was my first thought, but the direction of the rudder and gyro all check out. I can power up, yaw the heli and see it correcting as it should.

Nevertheless, I plan on going through the tail wizard from scratch once I install the new gear and get the boom back on. I want to start fresh because as you say, almost all situations like this turn out be user error in some way or the other.
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Old Sep 02, 2012, 06:46 PM
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Just a thought but Im a Futaba man other than a DX-7 for BnF stuff like Mcpx, 130X etc

I hat the DX-7 Gyro 0---50---100 with everything below 50 gbeing Rate mode and above 50 HH mode using a gear channel

I noticed the DX-8 has a gyro mode now like Im used to.

100---0---100 everything right of 0 is HH and left of 0 is Rate or normal mode

This little difference had me in a BLUR piro with the slightest bit of light skid action a while back but it wasnt a FBL heli

Another time I had my belt twisted the wrong way on my Century Swift and the same thing happened
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Old Sep 02, 2012, 08:19 PM
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Well guys, I'm going to have to eat crow and painfully admit that my issue was completely my fault.

Don was correct in the tail compensating the wrong direction, and for some reason I had missed it during the setup and several times checking after the small incident.

I was checking my setup over and over trying to figure out what was wrong and during what seemed to be the tenth time, I was checking my rudder stick movements with the tail blades. Right rudder...leading edge of tail blades point right, Left rudder...they point left so all is good.........wait a minute!!! I stood there in disbelief that I had missed this so many times, especially as many helis as I have built and set up.

My brain was just locked into the fact that the leading edge was moving the direction I was moving the sticks, despite the fact that this would give opposite nose travel and have the rudder reversed.

BTW, James Ive had that twisted belt issue before, and that will wake you up in a hurry when the heli leaves the ground!

Thanks for the feedback and suggestions guys. I'm going to go tuck my tail between my legs, repair my heli and pretend this never happened.
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