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Old 08-17-2010, 11:58 AM   #1
WBFAir
 
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Default Will carbon tail blades make my tail hold better?

Hello all

Even though I've replaced everything else and have greatly reduce my tail blow out problem on heavy punch outs, I still have it to a certain degree.

Right now I am using a set of the K&D tail blades and even though they are better then the Aligns, being plastic I gotta think they probably are flexing a little.

So I was just wondering if going with carbons would make any difference?

Thanks all.
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Old 08-17-2010, 12:48 PM   #2
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Originally Posted by WBFAir View Post
Hello all

Even though I've replaced everything else and have greatly reduce my tail blow out problem on heavy punch outs, I still have it to a certain degree.

Right now I am using a set of the K&D tail blades and even though they are better then the Aligns, being plastic I gotta think they probably are flexing a little.

So I was just wondering if going with carbons would make any difference?

Thanks all.
They would not really help with the blow out problem. You need more tails authority to hold the tail from blowout. You may need to increase your headspeed or make sure you have enough pitch range at the tail blades.

Using CF tail blades will help with the tail feel though. They make it more crisp and locked in.
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Old 08-17-2010, 01:13 PM   #3
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Try the tail blades for the 450 pro. They're longer, and give the tail rotor a bit more authority. Helped a lot on my stretch 450. Otherwise, higher head speed will help.
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Old 08-17-2010, 03:07 PM   #4
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Yeah right now I'm running 2900 in Gov mode with a Castle Creation 60 amo ESC in Gov mode to a Scorpion 2221-8

I know that may be a bit on the low side but its as about as safe as I want to go with using the woddies.

Basically in my opinion I feel the problem is stemming from the new 40C packs I am using.

As I mentioned I've replaced everything, the Gyro (went to a 520), new 9257, whole new tail, new belt and entire belt drive gear.

The belt drive gear gave me the most improvement and as well when I tore it apart to replace that, I removed the the aftermarket metal frames and put the carbons back in.

So again, all in all to me what is happening here is that the torque of the 40C I think is just to much, so one putting in Carbons for the mains so I can run say 3000+, I think with the those will also just increase the torque as well.

So as a result I was just wondering if with carbon for the tail, they may have more power against that torque.

From what I've seen I think the stock V2 blades are like 59mm an you can also get some K&B's that are 61 which I think are for the Pro.

But I wonder if there are Carbons for the Pro, if they would be 61 and that would be the most I could do?
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Old 08-17-2010, 03:35 PM   #5
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Yeah right now I'm running 2900 in Gov mode with a Castle Creation 60 amo ESC in Gov mode to a Scorpion 2221-8

I know that may be a bit on the low side but its as about as safe as I want to go with using the woddies.

Basically in my opinion I feel the problem is stemming from the new 40C packs I am using.

As I mentioned I've replaced everything, the Gyro (went to a 520), new 9257, whole new tail, new belt and entire belt drive gear.

The belt drive gear gave me the most improvement and as well when I tore it apart to replace that, I removed the the aftermarket metal frames and put the carbons back in.

So again, all in all to me what is happening here is that the torque of the 40C I think is just to much, so one putting in Carbons for the mains so I can run say 3000+, I think with the those will also just increase the torque as well.

So as a result I was just wondering if with carbon for the tail, they may have more power against that torque.

From what I've seen I think the stock V2 blades are like 59mm an you can also get some K&B's that are 61 which I think are for the Pro.

But I wonder if there are Carbons for the Pro, if they would be 61 and that would be the most I could do?
As you increase the headspeed you also increase the tailspeed.....but there is a lot more to this than that.

As your headspeed increases the amount of lift created increases more than the drag...it becomes more efficient.

The tailspeed increasing also does the same thing....so overall as you increase your headspeed the heli gets better at making lift and less drag.

So you may need to increase your headspeed...especially if you have the pro tail ratio which is designed for an even higher headspeed.

Having a higher C rating on the pack does the opposite when in Gov mode...it does not need to fight as hard. Actually a low C rating is worse because your headspeed drops too low and then you loose tail holding power.

What are your ESC settings? Does your headspeed drop a lot?
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Old 08-17-2010, 04:23 PM   #6
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I get what your saying about the head speed creating less torque as since its spinning faster yes it is creating more lift and as well has more inertia so I get more punch with less pitch and also it is harder to slow down but I kinda disagree on the higher 40C thing.

Basically the higher the C the higher your amps are going to be an thus more power and torque.

If you cut into the air with say a sudden 12 degree pitch at say 3000 RPM and especially have a Gov that is going to increase that torque to try to maintain that and stay at the RPM and thus the tail stays at what ever its too, that creates a the same amount of resistance in the air whether you are driving that from a 20C pack or 40C pack, But with less C that is less amps and so less torque and so that is going to put less of a amount of opposite torque driving the body of the helicopter in the opposite direction.

But with more C that means more amps are available an thus more opposing torque and if the reverse push capabilities of the tail at its maximum pitch is exceeded by that torque, it is going to override what the tail can do an thus push the tail no matter what until that torque is reduced back down to where the tail is within its capacity and can pull it back.

I would gather this is why the Pro model has a slightly bigger tail blade as with more surface area, it has a higher capacity to counter act the higher torques that helo is expected to see.

As well you can also see that this worked like this for me as when I was running and do run the 20C's I used to use, now, I don't have the blowouts.

Again and I mean no offense airjawe but I remember I looked at your stuff before and if I am reading your signature specs right, you are running a CC 45, I am assuming a 3S, the Scorpion -8 on a 14T, and are running 3400RPM.

Well if I plug that all into the CC software it tells me you are way exceeding the Govs capacity at 101.4%.

So one if this is what you're running and especially at 13+, first I don't think you are even quite getting 3400 even at hover but as well, have absolutely no capacity of power an thus torque left over to keep it at what ever RPM it is running at.

So as you are not seeing much if any added torque via a sudden application of pitch, I doubt you would have any problems with a blowout.

Basically though what you are doing if I have all your specs right is really not all that much different that as have in not in Gov mode so I don't know why you don't go with say a 15T as that will at least bring you down to 94% which is still kinda high so even better would be a 16T (if there is one of those) and that would give you 88% and that would give you lots of room to keep that at 3400.

Now at 3400 on a 450 you may not be seeing this as it is normally seen as the inertia and the efficiency on such a light bird for that speed is just as you stated, very high, so heck if you like it the way it is I guess why change but I just thought I would bring that up.

One thing I would mention though is to watch your amp load as I am pulling about 31 amps on my rig and with a 40C. So if you do go with the 15 or 16T, at 3400 and the added amps from the Gov working properly, you may be getting really close to that 45's limit,

Btw this is why I went with the 60amp unit an my balance is OK. If I may suggest, you might want to try the new ICE 50 as that has the nice data logger and can help you see a lot of these things.

Anyway back to me, so for me running even at 2900 or 3000, with the added power capacity I have left, and a 40C, I am going to see a very large opposing torque increase on a punch out so I need to figure a way to counteract that.

Btw I just ordered up a set of 62mm Carbons and a set of the 61mm Pro K&D's so I'll try those an see what comes

Hope that wasn't offensive.
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Old 08-17-2010, 07:57 PM   #7
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I get what your saying about the head speed creating less torque as since its spinning faster yes it is creating more lift and as well has more inertia so I get more punch with less pitch and also it is harder to slow down but I kinda disagree on the higher 40C thing.

Basically the higher the C the higher your amps are going to be an thus more power and torque.

If you cut into the air with say a sudden 12 degree pitch at say 3000 RPM and especially have a Gov that is going to increase that torque to try to maintain that and stay at the RPM and thus the tail stays at what ever its too, that creates a the same amount of resistance in the air whether you are driving that from a 20C pack or 40C pack, But with less C that is less amps and so less torque and so that is going to put less of a amount of opposite torque driving the body of the helicopter in the opposite direction.

But with more C that means more amps are available an thus more opposing torque and if the reverse push capabilities of the tail at its maximum pitch is exceeded by that torque, it is going to override what the tail can do an thus push the tail no matter what until that torque is reduced back down to where the tail is within its capacity and can pull it back.

I would gather this is why the Pro model has a slightly bigger tail blade as with more surface area, it has a higher capacity to counter act the higher torques that helo is expected to see.

As well you can also see that this worked like this for me as when I was running and do run the 20C's I used to use, now, I don't have the blowouts.

Again and I mean no offense airjawe but I remember I looked at your stuff before and if I am reading your signature specs right, you are running a CC 45, I am assuming a 3S, the Scorpion -8 on a 14T, and are running 3400RPM.

Well if I plug that all into the CC software it tells me you are way exceeding the Govs capacity at 101.4%.

So one if this is what you're running and especially at 13+, first I don't think you are even quite getting 3400 even at hover but as well, have absolutely no capacity of power an thus torque left over to keep it at what ever RPM it is running at.

So as you are not seeing much if any added torque via a sudden application of pitch, I doubt you would have any problems with a blowout.

Basically though what you are doing if I have all your specs right is really not all that much different that as have in not in Gov mode so I don't know why you don't go with say a 15T as that will at least bring you down to 94% which is still kinda high so even better would be a 16T (if there is one of those) and that would give you 88% and that would give you lots of room to keep that at 3400.

Now at 3400 on a 450 you may not be seeing this as it is normally seen as the inertia and the efficiency on such a light bird for that speed is just as you stated, very high, so heck if you like it the way it is I guess why change but I just thought I would bring that up.

One thing I would mention though is to watch your amp load as I am pulling about 31 amps on my rig and with a 40C. So if you do go with the 15 or 16T, at 3400 and the added amps from the Gov working properly, you may be getting really close to that 45's limit,

Btw this is why I went with the 60amp unit an my balance is OK. If I may suggest, you might want to try the new ICE 50 as that has the nice data logger and can help you see a lot of these things.

Anyway back to me, so for me running even at 2900 or 3000, with the added power capacity I have left, and a 40C, I am going to see a very large opposing torque increase on a punch out so I need to figure a way to counteract that.

Btw I just ordered up a set of 62mm Carbons and a set of the 61mm Pro K&D's so I'll try those an see what comes

Hope that wasn't offensive.
Not offended at all! I very well know that I run outside of what the software says for me to do. I also run my timing at max by the way(20). I do get 3400 by the way...confirmed with a tach....and it does it all through the flight. Bottom line is the software is a guideline. I chose to go the low gearing route and I do hit 100% throttle but my max amp draw won't be so high because of it...I actually get a lot of efficiency because of my setup(4.5 min flights of 2.75D..not quite 3D)....and it doesn't really bog either. Of course I could listen to the software and get my headspeed to stay completely still but then I would make more heat and pull more amps. Long story short...no offense taken! By the way I do appreciate your sensitivity and not coming out blazing.

Now to your heli... are you getting more of a blowout with the 40C compared with the 20C? I thought you were in Gov mode...are you not in Gov mode?

My experience has been that a weak battery will let the headspeed drop and thus get into a blowout...meaning a higher C pack will hold the tail better. Unless you are not in gov mode and your throttle curve is too aggressive and leading to a blowout from your headspeed trying to increase.

Maybe your one-way is giving? That would explain the tail holding with a weaker pack too.
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Old 08-17-2010, 09:07 PM   #8
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Quote:
Originally Posted by WBFAir View Post
Hello all
Right now I am using a set of the K&D tail blades and even though they are better then the Aligns, being plastic I gotta think they probably are flexing a little.
So I was just wondering if going with carbons would make any difference?
Thanks all.
I got some 60mm length CF tail blades. Next tail rebuild I'll weigh the
stock blades vs. the CF blades.

They are slightly longer and wider so they'll give abit more
tail authority. If all other variables stay the same then tail blades
with more surface area may provide an improvment. And you may
have to lower your gyro gain abit.

Best bet - lose $8.00 and try them out for yourself.
You're going to anyways one day!
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Old 08-17-2010, 11:15 PM   #9
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Originally Posted by WBFAir View Post
Basically the higher the C the higher your amps are going to be an thus more power and torque.

If you cut into the air with say a sudden 12 degree pitch at say 3000 RPM and especially have a Gov that is going to increase that torque to try to maintain that and stay at the RPM and thus the tail stays at what ever its too, that creates a the same amount of resistance in the air whether you are driving that from a 20C pack or 40C pack, But with less C that is less amps and so less torque and so that is going to put less of a amount of opposite torque driving the body of the helicopter in the opposite direction.

But with more C that means more amps are available an thus more opposing torque and if the reverse push capabilities of the tail at its maximum pitch is exceeded by that torque, it is going to override what the tail can do an thus push the tail no matter what until that torque is reduced back down to where the tail is within its capacity and can pull it back.
just cutting in, but your logic is completely flawed on this ..an important factor is mainblade weight, also a very important factor in mechanical gain - headspeed .. lipo has nothing to do with amps when it comes to the tail directly .. what it has to do with is voltage maintained under load and resulting headspeed .. the mains are tied to the tail and you can NOT change that .. tail blades will have a minimal impact compared to anything else, headspeed, mechanical gain, mainblade type and weight, overall pitch, collective management, heli weight .. lipo 'C' rating is low on the list of importance so are tail blades ..
.. other things i personally would worry about before changing a tailblade or worrying about which 'C' rating i was going to fly next out of my cheezy lipo collection are tail servo strength, my bec/power supply to the heli and its ouput, and the tail inkage .. a good way to see whats going on is strap it down GOOD and spin it up and nail the rudder both ways paying close attention to what the servo/slider/ and linkage are doing .. a slider failing to go full travel under load is a sure sign theres a problem, or a belt slipping .. thats just a first step i would take to observe the issue .. but once again, looking at lipo C rating or tail blades is missing the bulk of a tail problem even if you find a sweet spot it will work by jostling lipos and tailblades it wont be ideal ... the tail should work pretty awesome from just about any flyable headspeed or lipo when its close to right .. then tailblades can become a fine tuning aid and running similar lipos can make things alittle more consistent ..
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Old 08-18-2010, 04:48 AM   #10
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dze

Hope no offence taking but I can't quite understand all your verbiage and phrasing there so its kinda hard to get what it is your saying but if you read in the first post, I have replaced everything that I could think of relating to this so everything is new and as tight as can be.

The first thing I replaced was then entire rear tail assembly, this includes the housing, bearings, shaft, slider and all linkage parts and arms.

I then suspected my Gyro and installed a brand new GY520.

Then I found an intermittent bad connection in my 9257's lead wire so I replaced that servo.

Note on those last two, I used to setup my helo with the servo's position for center but full travel statically in non HH, but via many recommendations, including Futaba stating the GY520 needs center servo in flight, I went to that mode by adjusting the servo position on the boom with center trim (and radio end points and subtrim) for hover no drift flight, then switched back to HH. Then as the 520 allows variable travel adjustments to either direction, I set it up for full travel in both directions using the Futaba link and software and adjusted the travel till I got a buzz from it bottoming out, then back that off till it just stopped.

Lastly I replaced the belt and then the belt gear drive assembly.

Before I did this though I tested the drive assembly's belt hub by marking it an looking for any slippage, to which there was none anyway.

Lastly to list I am currently running a separate CC BEC and with the Castle software have confirmed it is set to 6V to which note that the 9257 is a 4.8 V an I am using the Align .7V stepdown.

In regards to this, I won't get into the whole world of voltage vers load but just note that the 9257 is what Futaba states is the best servo to use with the 520 and for everyone that does use that and runs 6V, this is the typical step-down that gets used that I have read.

So again, everything that could be gone over and replaced has been done so and all including any linkage movements is working correctly.

Then just to answer others, I was using a setting of the Gyro gain at 15 this Sunday and the blow out was its most minimum but as well the Helo was a real dog and its punch outs were no where near as powerfully as they would need to be to do any 3D stuff safely. I bumped that up to 20 when I got home and did some light testing in the backyard to which it seems like that may be enough but the blowout is more now.

I want to give that setting a test at the field and see if that is a good setting and if not maybe I'll try something between 15 and 20.


But just to note, it really is my desire nto to lower this as this basically is canceling out the whole reason for going with a 40C pack. If having less punch by crankgin down the gain till I don't get a blowout was the key, I might as well have gone with a 30C.


As far as the Gyro gain that is set to 40% in the radio and I have tried it lower and it has no effect on the blowout so I have gone back to 40.

To answer one last question, no I have not tried a new oneway bearing but in all inspections it does not seem bad but I'll get a new one an try it just for the heck of it.

At any rate hopefully that answers all question respectfully.
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Old 08-18-2010, 06:19 AM   #11
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dze

Hope no offence taking but I can't quite understand all your verbiage and phrasing there so its kinda hard to get what it is your saying but if you read in the first post, I have replaced everything that I could think of relating to this so everything is new and as tight as can be.

The first thing I replaced was then entire rear tail assembly, this includes the housing, bearings, shaft, slider and all linkage parts and arms.

I then suspected my Gyro and installed a brand new GY520.

Then I found an intermittent bad connection in my 9257's lead wire so I replaced that servo.

Note on those last two, I used to setup my helo with the servo's position for center but full travel statically in non HH, but via many recommendations, including Futaba stating the GY520 needs center servo in flight, I went to that mode by adjusting the servo position on the boom with center trim (and radio end points and subtrim) for hover no drift flight, then switched back to HH. Then as the 520 allows variable travel adjustments to either direction, I set it up for full travel in both directions using the Futaba link and software and adjusted the travel till I got a buzz from it bottoming out, then back that off till it just stopped.

Lastly I replaced the belt and then the belt gear drive assembly.

Before I did this though I tested the drive assembly's belt hub by marking it an looking for any slippage, to which there was none anyway.

Lastly to list I am currently running a separate CC BEC and with the Castle software have confirmed it is set to 6V to which note that the 9257 is a 4.8 V an I am using the Align .7V stepdown.

In regards to this, I won't get into the whole world of voltage vers load but just note that the 9257 is what Futaba states is the best servo to use with the 520 and for everyone that does use that and runs 6V, this is the typical step-down that gets used that I have read.

So again, everything that could be gone over and replaced has been done so and all including any linkage movements is working correctly.

Then just to answer others, I was using a setting of the Gyro gain at 15 this Sunday and the blow out was its most minimum but as well the Helo was a real dog and its punch outs were no where near as powerfully as they would need to be to do any 3D stuff safely. I bumped that up to 20 when I got home and did some light testing in the backyard to which it seems like that may be enough but the blowout is more now.

I want to give that setting a test at the field and see if that is a good setting and if not maybe I'll try something between 15 and 20.


But just to note, it really is my desire nto to lower this as this basically is canceling out the whole reason for going with a 40C pack. If having less punch by crankgin down the gain till I don't get a blowout was the key, I might as well have gone with a 30C.


As far as the Gyro gain that is set to 40% in the radio and I have tried it lower and it has no effect on the blowout so I have gone back to 40.

To answer one last question, no I have not tried a new oneway bearing but in all inspections it does not seem bad but I'll get a new one an try it just for the heck of it.

At any rate hopefully that answers all question respectfully.
When you say blowout are you saying that the tail moves a lot...maybe a 45-90 degree turn? We need to be on the same page on what the heli is actually doing. To me a blowout is when the tail moves out of line and stays out there something like 45 degrees at the minimum....and sometimes if it is real bad it'll do a complete piro unintentionally!! This all usually happens when you do a full collective move. Anyway can you describe the 'blowout' better?

Does your headspeed drop when you do a move?

Do you have vibes...vibes will make heli drift which may seem like a blowout sometimes.

How much pitch do you have at the tailblades? Ideally 45 degrees against torque and 35 with torque but a little less is fine as well.
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Old 08-18-2010, 06:34 AM   #12
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The blow out amount will vary upon the load.

In other words, if I just go from a hover and hit it, I might get a 1/8 of a turn of a kick of the tail to the right but especially with the 520 now, it then pops back pretty quick.

But if I take the helo up to say 30ft then drop it and nail it just before hitting the ground, then it can get to more like 1/4 (or 90 degree) amount of a kick that then the gyro doesn't really bring that back.

As far as the RPM dropping, that's hard to say for 100% sure.

Without a doubt I hear the load noise from both the mains and the tail from an act like this but its hard to tell if it is also dropping RPM as how can you?

But having said that, with my gearing and setup, it is setup for a 90% range @ 2900 (have also pushed it to 2950 too btw) so unless the ESC isn't working, I would suspect I am not getting much RPM drop if the Gov is doing its job and also I can tell a significant difference if its not in Gov.

As well to note, I have tried the ESC gain at both 15 and incrementally up to 55 and there really isn't much noise diff.

To some degree I wish I had the ICE in there so I could tell but at this point, one the 60 is working perfectly as far as I can tell, two I really don't want to have to do all the installation of a new ESC for no reason as well as spend the money for the same reason, and three I really don't want to lose that extra 10 amps of capacity as I have even seen ICE reports of the -8 with the 40c's and with the top load creating parts on it, the hitting almost 50 amps so I really want that cap.

Again this is another reason I'm looking at this as a torque issue.

Light load = light torque = light blowout.

Heavy load = heavy torque = heavy blowout.

Then to answer you question on the tailblade pitch, I had never really measure it with my pitch gauge but against the torque, IE the slider moving towards me, it is set up for the max range so if that is not enough, there's no more pitch I can give.

Btw a little note on that, I had set this up last week with the original plastic Tail Rotor Control Arm. Then the other night I replaced that with the metal one they have now that's from the Sport/Pro.

After that the next day I was working on the pitch stuff a lot and was doing a lot of playing and moving around of the helo in HH mode powered up and as the arm apparently is a slight different ratio, the tail servo kept buzzing from the slider bottoming out anytime I would move the Helo in the direction that was to compensate for against torque.

So I had to do the whole centering process again.

Point is, if that was happening from just me moving the helo around just on the bench, I think this is pretty confident proof that the whole tail system is working to it's max in the, give it its max pitch against torque operation.
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Old 08-18-2010, 04:50 PM   #13
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The blow out amount will vary upon the load.

In other words, if I just go from a hover and hit it, I might get a 1/8 of a turn of a kick of the tail to the right but especially with the 520 now, it then pops back pretty quick.

But if I take the helo up to say 30ft then drop it and nail it just before hitting the ground, then it can get to more like 1/4 (or 90 degree) amount of a kick that then the gyro doesn't really bring that back.

As far as the RPM dropping, that's hard to say for 100% sure.

Without a doubt I hear the load noise from both the mains and the tail from an act like this but its hard to tell if it is also dropping RPM as how can you?

But having said that, with my gearing and setup, it is setup for a 90% range @ 2900 (have also pushed it to 2950 too btw) so unless the ESC isn't working, I would suspect I am not getting much RPM drop if the Gov is doing its job and also I can tell a significant difference if its not in Gov.

As well to note, I have tried the ESC gain at both 15 and incrementally up to 55 and there really isn't much noise diff.

To some degree I wish I had the ICE in there so I could tell but at this point, one the 60 is working perfectly as far as I can tell, two I really don't want to have to do all the installation of a new ESC for no reason as well as spend the money for the same reason, and three I really don't want to lose that extra 10 amps of capacity as I have even seen ICE reports of the -8 with the 40c's and with the top load creating parts on it, the hitting almost 50 amps so I really want that cap.

Again this is another reason I'm looking at this as a torque issue.

Light load = light torque = light blowout.

Heavy load = heavy torque = heavy blowout.

Then to answer you question on the tailblade pitch, I had never really measure it with my pitch gauge but against the torque, IE the slider moving towards me, it is set up for the max range so if that is not enough, there's no more pitch I can give.

Btw a little note on that, I had set this up last week with the original plastic Tail Rotor Control Arm. Then the other night I replaced that with the metal one they have now that's from the Sport/Pro.

After that the next day I was working on the pitch stuff a lot and was doing a lot of playing and moving around of the helo in HH mode powered up and as the arm apparently is a slight different ratio, the tail servo kept buzzing from the slider bottoming out anytime I would move the Helo in the direction that was to compensate for against torque.

So I had to do the whole centering process again.

Point is, if that was happening from just me moving the helo around just on the bench, I think this is pretty confident proof that the whole tail system is working to it's max in the, give it its max pitch against torque operation.
Just for kicks try a higher headspeed and see if it still does it?
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Old 08-18-2010, 05:34 PM   #14
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Get rid of your wooden blades - they would flex pretty hard on those punch outs and put untold strain on your system.

So I would do this - get CF main blades - run a 100% throttle curve - and NO GOVERNOR.
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Old 08-19-2010, 12:12 PM   #15
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Originally Posted by airjawed View Post
As you increase the headspeed you also increase the tailspeed.....but there is a lot more to this than that.

As your headspeed increases the amount of lift created increases more than the drag...it becomes more efficient.

The tailspeed increasing also does the same thing....so overall as you increase your headspeed the heli gets better at making lift and less drag.

Ok Iím a bit late but I noticed your statement and have to correct you cuz, well, itís not entirely correctÖ In fact, itís rather misleading.


The L/D ratio does not increase with airspeed, in fact itís quite the opposite, and yes, itís a bit more complicated then that.

First thing you have to understand is the fact that there are actually multiple forms of fluid dynamic drag that are affecting the rotors; Iím gonna try to explain the 2 most important onesÖ

-Induced drag: Is created by the lift generated by the wing, at slower air speeds a higher angle of attack is needed to sustain lift. A higher angle of attack leads to a higher amount of induced drag, so this form of drag will decrease as head speed increases because at a higher head-speeds the rotors need less pitch to create lift.

-Profile drag: AKA wind resistance AKA parasite drag AKA a lot of things... Has nothing to do with angle of attack, itís simply the drag created by friction... And it increases exponentially with airspeed.

So, as you increase head-speed you need less pitch to hover (meaning your experiencing less induced drag) however total induced drag at its highest point is less then total profile drag at a high head-speed.

Here is the important part; With a higher head-speed your profile drag will naturally be higher then with a medium or low head-speed right? Right...
When you add pitch you are essentially increasing angle of attack therefore increasing induced drag. So, considering the fact that induced drag and angle of attack go hand in hand, with a higher head speed a pitch pump would create MUCH more drag then at a lower head-speed? Why?
Because at a higher head-speed your profile drag is already high, when you punch the pitch you suddenly increase angle of attack which in tern increases induced drag... Meaning your total drag is higher then it would be if you were doing the same pitch pumps at a lower RPM.

This creates more torque that the tail rotors will need to compensate for...
Increasing head-speed will not solve your blowout issues... My guess, its slop thatís causing the issues, not head-speed. Unless of course your head speed is really THAT low, in which case you would have a lack of authority and terrible performance all around.


Anyway, just thought I would add that.
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Old 08-19-2010, 04:07 PM   #16
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Originally Posted by Vicovaludemero View Post
Ok Iím a bit late but I noticed your statement and have to correct you cuz, well, itís not entirely correctÖ In fact, itís rather misleading.


The L/D ratio does not increase with airspeed, in fact itís quite the opposite, and yes, itís a bit more complicated then that.

First thing you have to understand is the fact that there are actually multiple forms of fluid dynamic drag that are affecting the rotors; Iím gonna try to explain the 2 most important onesÖ

-Induced drag: Is created by the lift generated by the wing, at slower air speeds a higher angle of attack is needed to sustain lift. A higher angle of attack leads to a higher amount of induced drag, so this form of drag will decrease as head speed increases because at a higher head-speeds the rotors need less pitch to create lift.

-Profile drag: AKA wind resistance AKA parasite drag AKA a lot of things... Has nothing to do with angle of attack, itís simply the drag created by friction... And it increases exponentially with airspeed.

So, as you increase head-speed you need less pitch to hover (meaning your experiencing less induced drag) however total induced drag at its highest point is less then total profile drag at a high head-speed.

Here is the important part; With a higher head-speed your profile drag will naturally be higher then with a medium or low head-speed right? Right...
When you add pitch you are essentially increasing angle of attack therefore increasing induced drag. So, considering the fact that induced drag and angle of attack go hand in hand, with a higher head speed a pitch pump would create MUCH more drag then at a lower head-speed? Why?
Because at a higher head-speed your profile drag is already high, when you punch the pitch you suddenly increase angle of attack which in tern increases induced drag... Meaning your total drag is higher then it would be if you were doing the same pitch pumps at a lower RPM.

This creates more torque that the tail rotors will need to compensate for...
Increasing head-speed will not solve your blowout issues... My guess, its slop thatís causing the issues, not head-speed. Unless of course your head speed is really THAT low, in which case you would have a lack of authority and terrible performance all around.


Anyway, just thought I would add that.
Long story short...why does a heli not hold its tail when the headspeed is low? And then why does it then have improved tail control as the headspeed increases.

If you graph it all you will see that as you increase your headspeed the amount of drag does increase(in the head which creates the torque)...but the amount of tail thrust increases more than the drag does(which counters the torque)....therefore improving tail performance.
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Old 08-19-2010, 10:20 PM   #17
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Long story short...why does a heli not hold its tail when the headspeed is low? And then why does it then have improved tail control as the headspeed increases.

If you graph it all you will see that as you increase your headspeed the amount of drag does increase(in the head which creates the torque)...but the amount of tail thrust increases more than the drag does(which counters the torque)....therefore improving tail performance.


Which is why I said this in the end:
"....Unless of course your head speed is really THAT low, in which case you would have a lack of authority and terrible performance all around."

But he said his head-speed is 2900rpm, so head-speed doesn't sound like the culprit... Not to me anyway.

Do you have access to a wind tunnel and all of the equipment necessary to calculate the optimal airspeed for the airfoil that your rotors utilize? I doubt it, therefore you would not be able to graph it out all by yourself... However, if you take a look in a physical fluid dynamics text book you will see that the work has been done for you already, and that work all points to your head-speed theory being incorrect.

Any given airfoil is most efficient at a specific speed, the effect you are describing is the result of high induced drag due to a high angle of attack. With a low head-speed your helicopter requires a higher angle of attack to achieve lift, because the airfoil used (symmetrical/high performance) is most effective at a higher airspeed the angle of attack required to achieve lift creates too much induced drag and causes a lack of authority, which translates into poor handling characteristics.

Induced drag is what would causes a heli to bog out on pitch pumps, that bogging could theoretically cause blow-outs, but if that's the case neither a higher head-speed nor CF tail-rotors will help.

WBFAir
I would take dze's advice here... Sounds like it may be slop, slipping belt, gain set too low, some binding in the tail or maybe even a few of those combined.
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Old 08-20-2010, 02:46 AM   #18
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WBFair...what are your esc settings? Exactly which heli is this on?
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Old 08-20-2010, 11:32 AM   #19
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Hey guys sorry not to reply in a bit but I've been doing some testing but am still having the problem.

As there is a lot here, its really to much to get into any one point but just to mention for anyone talking about some issues with certain parts, bare what I will describe below, please go back through this as I have described how I have replaced virtually every part that is conceivably related to this with new ones and they are all setup, and working correctly and also note that I did this basically on part by part by part and tested basis over the past two weeks and none of them has been the smoking gun per say.

About the only thing that has some effect was when I replaced the tail belt drive assembly and that had some slight improvement but not by much.

So to mention the one part I haven't replaced yet is the One-way Bearing, (not that I think its bad) but I have one coming and a new One Way Bearing Shaft and that should be here today or tomorrow and will be replacing that.

Next to bring things up to speed, last night I put on a set of the 61mm K&D Pro tail blades and that has helped some, at this point now I don't get any blow out from a punch at hover but on a hard drop I can still get a full 1/4 turn. I also got a set of carbons but didn't try those as the K&D actually had much more surface area so I figured if anything they would probably be the same but being yellow, the K&D's are much easer to se.

Then I also tied a set of Maverikk carbon blades to give that a test and this had no effect either.

So at this point I'll try the one-way and see what happens, and if after that nothing changes I guess I just have to give up.

But thanks everyone for all their help and points, I think it was a very good discussion that a lot of people learned stuff from.

Btw J, the helo is a Trex 450SE V2 and below is a pic of the ESC settings.

Note, the only thing right now that is actually not right on that is that the Gov gain is set to 20 not 25, this actually helps a bit as the torque of a punch is a little softer. Again I have tested this from 15 all the way up to 55 and there is a very slight diff but its hardly worth mentioning it but at 15 the blowout is a little less and at 55 its more. But 15 is to low and it really cuts into the power ability so I don't like to run it that low. Actually even 20 is kinda low too and I really wish I could run it higher but because of the blowout I'm using it as a happy medium for now.

Also note on this, that these setting are all derived from a full days worth of, and even further on going, conversations and e-mails with Steve Rodgers who is Castles top Helo tech and the drafter of all their ESC setup instructions and these are the settings we have come up that, outside of the blowout issue, I will say have made my helo fly better then it ever has before.

And again in one respect to that, with all these settings, if I put one of my old 20C packs in, I don't get the blow-out.


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Old 08-20-2010, 02:06 PM   #20
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My gain is something like 13... not sure why you are so high and maybe that says something about your batteries or that your gain is overdriving and causing powerloss? I don't know but have you seen the 3 documents in CC's website on how to set gain? They are at the bottom of the page that has all the support stuff.

In order to rule out the gain/gov mode try to fly it with a flat curve in non-gov mode. You won't have to do anything other than change modes and then set the throttle curves at something flat above 85. Try a 100 flat and if still does it with that then you've got some slip or some really lame batteries.
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