How smooth a TDR looks to an SK-720

[mkovalcson]

The Jive's BEC is doing a great job as expected.

Right now I have absolutely no tail wag, and the tail is locked in. I haven't been able to shake it yet. It flies smoothly with now outward signs of vibration.

This is just a log from me flying it around in the back yard today.

This baby is dialed in!!!!!

To be clear the blue line is not the actual throttle value, but the vibrations at those throttle settings.

[airbound]

That looks great +1 --What servos are you running ? Mine is due in May--still undecided on servos-What heat sink are you using on the JIve ? Thanks Walt

[mkovalcson]

I'm using BLS 451's and a BLS 251 for servos.

My heat sink is not standard. NoteL The motor mount is upside down in this picture.

[Groucho_]

Mark,

Try 1700 RPMs and over... I have a feeling it won't look so smooth to the SK-720.

The self leveling function is lost at those RPMs on my bench tests - Red LED on the SK.

[mkovalcson]

Originally Posted by Groucho_

Mark,

Try 1700 RPMs and over... I have a feeling it won't look so smooth to the SK-720.

The self leveling function is lost at those RPMs on my bench tests - Red LED on the SK.

What pinion, motor and throttle settings are you using?

I thought you had a pretty stock setup just like mine.

I've heard that the graph on Page 41 of the TDR manual is off so I can't guarantee I was running these head speeds.

But they show the following with a Jive 80HV and Pyro 700-52 and 13T.
24% = 1400 rpm
48% = 1700 rpm
60% = 1850 rpm

I have a 120HV, but I wouldn't expect that to throw things off.

The comments on that page also mention the battery condition and I'm running relatively new TP 65C 4400mah batteries and had these charged on my PowerLab 8 V2 as an accurate charge to 4.2V per cell.

I haven't taken my digital tach out to see what head speeds I'm getting, but I'll see if I can get some baselines today.

The one thing that made the absolute biggest difference on tail vibration to me was the castle gear to TT umbrella mesh. If it is a bit too loose the vibrations go sky high, and too tight isn't very good either. I also have a good coat of MolyKote EM-50L in there which could dampen a bit of the vibrations.

I went through 3 iterations to get my castle gear / umbrella gear mesh where it is. A difference of a 0.26mm shim resulted in almost triple the vibs, I had. BTW I still have my 3 TT support bearings where the small sheet suggested. I hadn't repositioned them yet based on your testing.

[Groucho_]

Originally Posted by mkovalcson

What pinion, motor and throttle settings are you using?

I thought you had a pretty stock setup just like mine.

Yes, pretty much... Stock 13T Pinion, Pyro motor and helijive.

For throttle, I'm letting the SK govern the head-speeds, and in testing, I can go to 1450 with vibes at less than 0.60, and to 1550 with vibes less than 1.80. However once I start pushing 1600 things don't look as nice, with the SK SL going into tilt once I touch 1700.

With the helijive governing, vibe results were identical.

These figures are all without main blades - just bench tests - I've not had the chance to actually fly yet

Originally Posted by mkovalcson

But they show the following with a Jive 80HV and Pyro 700-52 and 13T.
24% = 1400 rpm
48% = 1700 rpm
60% = 1850 rpm

I have a 120HV, but I wouldn't expect that to throw things off.

In case it helps you, my Helijive throttle settings for 1350, 1450 & 1550 RPMs were 52%, 55% & 58%. This according to the SK playback log. The Helijive is also 120HV, so I'd expect that the figures would be similar. I don't recall if I enabled lower RPMs on the helijive for that test though...

Originally Posted by mkovalcson

The one thing that made the absolute biggest difference on tail vibration to me was the castle gear to TT umbrella mesh. If it is a bit too loose the vibrations go sky high, and too tight isn't very good either. I also have a good coat of MolyKote EM-50L in there which could dampen a bit of the vibrations.

I found that even removing the tail boom support struts made a difference in vibes. Essentially the main body of the machine seems very smooth, but the tail system seems to open the door to vibes at multiple points.

I haven't put any grease on the umbrella and TT gears - Indeed I've not put grease anywhere yet. However, although the Molykote would help in dampening vibes (and I will apply some if I get some), I highly doubt it would dampen them enough to keep the SL active at those 1700 RPMs.

Jan had told me that "There are always some points were the tail rotor is running less smooth which is not a problem if the flybarless electronic works well."

In fact he's correct - the FBL gyro does work well - It's only the SL that's thrown off by the increase in vibes at speed - Which is a pity nonetheless .

[abanihani]

Mark, I doubt you are getting those headspeads and I agree with Groucho on his estimates for his HS. I have tached mine last weekend and I got
30%~900 rpm
55%~ 1450 rpm
65%~ 1720 rpm.

This is on heliJive mode 6, 13T pinion and pyro motor. I am not sure how Jan got his HS in the manual. I will experiment this weekend with 14T pinion and mode 4 to see what I get for head speads.

[Groucho_]

Just checked one of my early posts on another thread, and yes, I too was using mode 6...

[mkovalcson]

Well my optical tach didn't work so I have no values.

So I decided to take it for a spin and then I did something stupid.

I landed it on my concrete patio from too much of a distance and at the last minute I slipped off the side of the concrete ledge.

So I'll be digging in my parts box ( 2nd TDR kit )

stripped main gear all other gears and umbrellas look fine.
boom
I assume the TT
CF tail rod
One main link
main and tail blades.

I'll verify my bearings and shafts are still good as well. I hit the TH but not in time.

Oh well. This was going to happen sooner or later, but this hurts because it was just a bad call. I should have walked in closer to my concrete pad before landing. As it is there is a retaining wall on one side and I have a wheel barrel and some potted plants on there. I had no business trying to land from the distance I was at.

New blades are on the way. I should have the rest of the heli perfect before they get here.

My TDR lost its virginity today

[abanihani]

Oh man, I am so sorry to hear that. Mistakes happen all the time so I would not worry about that. After all they are machines for us to have fun. Let me know of you need any part missing as I have an unused kit

[mkovalcson]

Originally Posted by abanihani

Oh man, I am so sorry to hear that. Mistakes happen all the time so I would not worry about that. After all they are machines for us to have fun. Let me know of you need any part missing as I have an unused kit

Thank you for the offer! I'm not worried, I've made my share of mistakes and this won't be the last.

However as I mentioned I also have an unopened TDR kit. It just took a while to get here. See below!

I guess I have to cut the box open now...
But that is what I got this second kit for !

[ZuvieleTeile]

Sorry Mark, that was too bad. . .
But hey, we learn from our mistakes.
I feel with you!!

@ Groucho
Bench tests have some value, but also they create sometimes vibrations.
Same when spooling up on a concrete or asphalt slab. Our flb systems don't like this too much. Better spooling up on lawn or a rubber mat, if you have to use a hard surface.

In essence, the vibrations in hovering are much different.

[mkovalcson]

So are you going to get two Diablo kits to have spare parts for it as well ?

At this point I'm thinking that I have enough helis that I can afford to be down one bird.

However, I think I'll go ahead and order the replacement parts for this as soon as I have my TDR running perfectly again and am sure I've replaced everything that needs replacing. I like having a whole bird worth of parts in the drawer for this heli as it is my favorite by a long shot.

[SimStream]

If you goto to view in the setup sk software and choose playback options and choose show rpm bottom left. Then playback that log thru the setup software (the one that shows a mini heli) it will tell you what rpm was at every stage. You can also see a graph of rpm on the software you were using.
I had no problem with vibes using the futaba foam and metal plate when i had a tdr
In mine and others opinion The sk probably has the best tail in the fbl business

[abanihani]

I ordered one only for the Diabolo, I also have too many helis to worry if one is down, in that event I will just order parts which at least are much easier to get than a new kit. The beauty of Diabolo is the availability
Of parts in the USA so I guess the turn around is much faster

[mkovalcson]

Originally Posted by SimStream

If you goto to view in the setup sk software and choose playback options and choose show rpm bottom left. Then playback that log thru the setup software (the one that shows a mini heli) it will tell you what rpm was at every stage. You can also see a graph of rpm on the software you were using.
I had no problem with vibes using the futaba foam and metal plate when i had a tdr
In mine and others opinion The sk probably has the best tail in the fbl business

That doesn't work unless you have a motor speed sensor going to the SK-720.




The best I can get is this which shows the Throttle percentage.

[Groucho_]

Mark,

Since you're rebuilding (sorry to hear about that...) - roughly attach a hyperion sensor to an esc/motor connection, spool up without blades and find out what throttle percentage you need to get the RPMs you want.

Then, since you're using the Jive governor, remove the sensor from the equation and finish the build...

It took me five to ten minutes to find my values for the Helijive. Though I kept the sensor installed, and will be using the SK Governor, but I can switch whenever I want/need, and have the Helijive values ready at hand...

[mkovalcson]

Originally Posted by Groucho_

Mark,

Since you're rebuilding (sorry to hear about that...) - roughly attach a hyperion sensor to an esc/motor connection, spool up without blades and find out what throttle percentage you need to get the RPMs you want.

Then, since you're using the Jive governor, remove the sensor from the equation and finish the build...

It took me five to ten minutes to find my values for the Helijive. Though I kept the sensor installed, and will be using the SK Governor, but I can switch whenever I want/need, and have the Helijive values ready at hand...

I'm sorry, but I don't have a hyperion sensor on hand and I really don't want to solder any wiring to the motor or ESC wires.

I just want my heli flying well again

[ZuvieleTeile]

No JLog yet Mark?

Tzzzz

[mkovalcson]

Originally Posted by ZuvieleTeile

No JLog yet Mark?

Tzzzz

Not yet. I'm not really pushing anything hard enough to need it.

And if I build a Diabolo I'll probably get a Kosmik ( assuming they work well ) which has an sd card and will do all the logging for me.

I love to have lots of information, but I don't want a bunch of stuff cluttering up my helis.

I think the Kosmik with higher current BEC and SD card will be a really cool product.