Why does the Blade 400D feel so different?

[traeside]

Okay I don’t have a lot of fly time but I normally can keep my Belt CP in hover in my garage for full packs without doing any touch and goes. I talked my buddy into getting the Blade 400D because of the DX6I and I had heard it is a great heli. So right off the bat I tried hovering his 400 and the thing just seems so touchy the head speed needs to be so high to get it to lift off and then it just seems far too sensitive to inputs. The littlest pull back on the throttle and it will set down like it is jumping to -12 pitch. I checked it in throttle hold and it is only going to -2 but it just seems like I need to get the head speed down so it is not hopping all over the place. I gave it a few turns to increase the pitch and it still does not lift off anywhere as easy as mine. I am using Align 325 pros. (Anyone use bigger blades?) Blades are balanced and tracking is spot on. Is this just how it is and he is going to learn this way? Is this how my T-Rex 500 I am building is going to feel?
Okay last question the elevator servo died so I put in an E-flite EFLD75 servo replacing the original EFLD75H servo. Io called E-flite and they said they are the same but I am not sure if this is adding to my problem I looks to be slower.
Thanks for any help

[sokal]

the 400 will fly much diffrent than the cpp
i have both to help with the touchyness raise you expo to about 20 on the aile and elev
3/4 stick is about 75% rpm and a 3 foot hover normal
some have changed thier throttle curve to help with rpm issues i used stock settings

but now i mostly fly in stunt mode to 90-100% rpm all the time

mosly you will just have to get used to her shes quite powerfull and agile

[sokal]

on the servo note
its best to use all the same servos in the cyclic area

i have the JR combo thier are other who use the spectrum combo and know how to set it up

[carlo_the_wonder_frog]

Instead of reducing headspeed by lowering the values in your throttle curves, you should really install a smaller pinion. ESC's like to be at 80% or more throttle all the time, they are most efficient that way.

[sokal]

hey carlo so i should lower my thro to 80 all across
i use 100-95-90-95-100

seems to fly well
what is a better recommendation

[Wolfpackin]

As usual, Carlo is correct.
I'm running my throttle curve at 0-40-80-90-100 in Normal mode.
I think the heli is more solid and responsive that way.
You just need to acclimate to the noise and power of the heli and you'll be fine.
If you find that the heli is too responsive or twitchy then go ahead and add some positive expo until you adjust to the small inputs required to control it.

[Wolfpackin]

sokal,

Not that I know as much as you two but I think you are fine with that curve.
I spoke to Jim Robertson, father of Jamie Robertson from the youtube videos, on the phone not too long ago. He told me Jamie runs 100% across the board with the stock setup and Radix blades.

Sparx will disagree, but I know of many people who are running the same curve as you or higher. A lot of it is personal preference but I don't think there is any problem with the head handling these speeds. And there is definately no issue with the motor running at 100% or close most of the time. As Carlo stated they like 80% or higher to be efficient.

[traeside]

Oaky guy’s thanks for all the info lets see if I can just get use to the ride. Thanks
As for the servos I am hoping the H at the end of the original servo just indicates that it was included with the model kit. And that is what E-flite said it was. I was just checking because it looks to lag behind a bit.

I think maybe i will look for a smaller pinion as well
thanks again,

[sparx-]

Not so much disagree Wolfpackin, just a matter of preference. I personally do not like running headspeeds of 3000rpm+ on plastic and wood blades. It is risky and I am not willing to take that risk. Others are and that is their preference. Right now I am running 2900rpm and that is only because if I lower my throttle curve anymore it will bring the motor out of it "power band" and make it less efficient. I am going to be ordering a 9T pinion to bring my headspeed down closer to what I like. I have 9T pinions here, but the Stock motor has a stepped shaft and requires you to use Eflite Pinions ( shocking :) ).

Also, in my past experience, I have found that running Plastic Head Blocks are 3000rpm+ start showing just how out of balance the HeadBlock is. There is a reason Align started putting CNC Alum Headblocks on their SA and S Helis.

I have no doubt that Jamie has no issues running 100% throttle. But you have to remember, he is in a different class of flying then most of us. His collective management is many times better then mine for sure. This means ALOT when you are talking about the stress you put on a heli and its power system.

SPaRX

[Wolfpackin]

Fair enough.:)

And part of the reason I'm running a higher headspeed is because of my altitude of 8,000FASL. I found the stock curve just didn't have any punch.

And on top of that I don't use full collective yet so I'm not getting near 100% throttle. I'm usually around +/-90%.

[glassier]

Okay I don’t have a lot of fly time but I normally can keep my Belt CP in hover in my garage for full packs without doing any touch and goes. I talked my buddy into getting the Blade 400D because of the DX6I and I had heard it is a great heli. So right off the bat I tried hovering his 400 and the thing just seems so touchy the head speed needs to be so high to get it to lift off and then it just seems far too sensitive to inputs. The littlest pull back on the throttle and it will set down like it is jumping to -12 pitch. I checked it in throttle hold and it is only going to -2 but it just seems like I need to get the head speed down so it is not hopping all over the place. I gave it a few turns to increase the pitch and it still does not lift off anywhere as easy as mine. I am using Align 325 pros. (Anyone use bigger blades?) Blades are balanced and tracking is spot on. Is this just how it is and he is going to learn this way? Is this how my T-Rex 500 I am building is going to feel?
Okay last question the elevator servo died so I put in an E-flite EFLD75 servo replacing the original EFLD75H servo. Io called E-flite and they said they are the same but I am not sure if this is adding to my problem I looks to be slower.
Thanks for any help
I've tried the Align blades and you don't get near the lift from them as you would from a properly balanced set of stock blades. Just a thought.;)

[swooper]

Hey Traeside, looks to me that his swashplate is too low, thas why it has no negative pich, you should be able to set it to get pitchs around 10 degrees on the high and low points.

[traeside]

Glassier I did notice less lift from my Align blades then a set of cheepo blades I was running on my belt CP. I will look around and see if I can find some with better lift.
Thanks
Swooper it was at -10 and 10 I went to -8 and 12 but it did not help so I think I will get 9T pinion like some of you are running.
Note on the Servo even though E-flite told me on the phone the DS75 and the DS75H were the same, They are NOT the same I took them apart to compare and the gearing (number of teeth) is different. So that was a big part of my problem in trying to fly the thing the other night. sense it was the elevator servo and it was running slower I was constantly over compensating.

[dieselracer]

A stock B400 at 100% tachs in at 2800 RPM with the stock battery. Which is fine for woodies. I have tached 4 B400 with the same results. I say you just get used to the "touchy" B400. As you get better you will actually like the faster response. I have flown many B400's and they actually respond very slow for me. Just get used to it. Because eventually you will want it more responsive.

[traeside]

A stock B400 at 100% tachs in at 2800 RPM with the stock battery. Which is fine for woodies. I have tached 4 B400 with the same results. I say you just get used to the "touchy" B400. As you get better you will actually like the faster response. I have flown many B400's and they actually respond very slow for me. Just get used to it. Because eventually you will want it more responsive.

Yeah I was thinking that people were going to say that, I guess I just got lucky starting with my Belt CP as it flies way easer. Now I am not looking as forward as I was to finishing me T-Rex 500. if it is that touchy I am going to be banging into everything LOL

[newhelliguy]

The larger heli should be more stable. I just built a trex 600 and it is very stable. I bought a used b400 and It didnt have servos so I put my original servos and I could not even controll the heli. The main heli guy at my local field could not even fly it. If your stock servos are not good(most of the time) this heli is not really controllable. After I replaced my servos with hs65 it was very easy to fly. it may be your servos are not working properly because the larger the heli the more stable it is all thing being equal. My 600 is very stable as Im sure your trex will be as well as your 400 if it is the servos that are the problem.

[sparx-]

A stock B400 at 100% tachs in at 2800 RPM with the stock battery. Which is fine for woodies. I have tached 4 B400 with the same results. I say you just get used to the "touchy" B400. As you get better you will actually like the faster response. I have flown many B400's and they actually respond very slow for me. Just get used to it. Because eventually you will want it more responsive.

Man.. I must have a hot motor then. With 335mm Align Wood Blades, mine tached at 3000rpm at 0 pitch with 90% throttle.

I just tached mine again tonight, this time with 315mm Align Blades and it tached at 3000rpm at 0 pitch with 80% throttle.

Granted I am not using the Stock battery, but I would not expect to see that much of a difference.

SPaRX

[eugenefelisco]

Man.. I must have a hot motor then. With 335mm Align Wood Blades, mine tached at 3000rpm at 0 pitch with 90% throttle.

I just tached mine again tonight, this time with 315mm Align Blades and it tached at 3000rpm at 0 pitch with 80% throttle.

Granted I am not using the Stock battery, but I would not expect to see that much of a difference.

SPaRX

Your drive train and esc still stock? Why do you have soo much headspeed? I gotta borrow a tach meter and do mine also.

[SeaComms]

In an ideal world, the 3800kv motor will run at 3800 rpm per volt. Assuming the battery is actually running at 11.1 volts, no load on the motor (0 pitch) and no loss, you should have a headspeed of 3012rpm. Add in to this a motor efficiency of around 85% (an average) and this will drop to 2561rpm. Looking at a flight logger (from another forum) on a stock Blade 400 it was averaging approx 10 volts flying in normal mode doing basic forward flight.

Assuming perfect efficiency, this translates to 2714 rpm, but in the real world with the efficiency factor thrown in, this would drop to about 2300 rpm.

So yeah - you have one hot motor :)

NOTES. Calculations based on 10 tooth pinion and 140 tooth main gear for a reduction of 14 to 1. Battery voltage from the flight logger data was taken from this post (http://www.rcgroups.com/forums/showpost.php?p=9604333&postcount=3129) on RCgroups.

[sparx-]

SeaComms, first off, that guy is not using a Stock battery. And that Lipo he is using in those graphs must be absolute crap. It does not hold voltage well at all.

I posted datagraphs of one of my flights here..........

http://www.helifreak.com/showthread.php?t=68901

That is a Stock Motor and Stock Esc on a 10T pinion. I was running a very MILD throttle curve at that time. That flight was almost constant flips, loops and rolls. It was holding the RPM up pretty good around 2600-2700 rpm.

I am not running a 100-90-80-90-100 throttle curve. And it holds 2900 rpms pretty consistantly. That is the TC I am running in the last video I posted yesterday.

So I am really lost as to what is different between my setup and other peoples. The only thing I can think of is the Batteries we are using. These LoongMax Lipos really hold their voltage well. Maybe the Stock Blade 400 lipo does not?

SPaRX

[SeaComms]

Hey Sparx, just looking at those graphs of yours, and yes, your battery is holding much more like I would expect - the drops to 9.3 on that other one are scary - I would have stopped flying to see what the hell was wrong if I saw that...

On yours, at point 1 minute 51 seconds on the second graph, you have pretty much exactly 11 volts. So I used this and did a quick calculation and with no loss (100% motor efficiency) you should get 2985 rpm. When you then look back at graph number one, thats exactly where it is.

So how does the logger work out what the head speed is? Is it based on a formula that is maybe not allowing for motor efficiency percentages? or is it measuring something like pulses to the motor or what? How do they work?

EDIT: Or, am I wrong in the thought that the motor efficiency rating effects the overall speed? (just a thought when out the back havin a smoke......)

Not having a dig at ya, just curious......

[sparx-]

The Datalogger logs the actual RPM of the motor via the feedback pulse. I then use that to apply a formula with the gear ratio to get the actual RPM of the head. I have also verified these RPMs with an Optical Tach to verify that the datalogger is getting the correct results and it is.

Like I said, I am baffled as to what is going on. I have my throttle curves on those charts. And I have checked with my Tach numerous times at 0 pitch to verify my findings. If you ask me, its like this motor is not 3800kv, but more like 4100-4200kv.

I have been running numbers for weeks on those calcs. I just do not get it. We both know that there is no way that these motor are running at 100% efficiency. It just does not happen in the real world.

This is all a mystery to me :). But I can tell you this, if I up my throttle curve to 100-95-90-95-100, I am getting 3100 rpms on my tach. With 100-90-80-90-100, I am getting 2900. And I have taken these measurement probably 10 times each now.

SPaRX

[SeaComms]

Wow.... as you say, it sounds like it is not a 3800kv motor. In the graphs it seems to hold the head speed pretty well while flying too, so power is not an issue either.

Would love to see some others run the same tests to see if that sort of headspeed is consistant with this motor across the board (well, actually would love to run it myself).

Guess in the long run its not a really big deal, just my curiosity getting the better of me!! I should be more concerned about actually flying the damn thing!

[sparx-]

Believe me.. I have been scratching my head about this for weeks. I need to order a 9T pinion so I can run the motor closer to 100%. I really do not like having a throttle curve that goes below 85% and I do not need 3000rpm. 2800rpm is just fine in my book.

SPaRX