How smooth a TDR looks to an SK-720

[Groucho_]

Originally Posted by mkovalcson

I really don't want to solder any wiring to the motor or ESC wires.

No need to solder - Thats what I meant when I said to attach it roughly to the connection... Just wedge that really thin wire between the male and female connectors.

A sensor is a good thing to have on hand to set your head speeds, and the Hyperion sensor is very inexpensive, the cheapest thing on the TDR in fact...

[mkovalcson]

Originally Posted by Groucho_

No need to solder - Thats what I meant when I said to attach it roughly to the connection... Just wedge that really thin wire between the male and female connectors.

A sensor is a good thing to have on hand to set your head speeds, and the Hyperion sensor is very inexpensive, the cheapest thing on the TDR in fact...

OK, next time I order some heli parts then. I've already got my order in for new blades, and I'm not ordering this by itself.

[abanihani]

I knew it, I smell a Diabolo on the way to you Mark. I will post photos when I get mine, hehehe

[ZuvieleTeile]

I know, you want one of those Mark. . .

Otherwise It wouldn't be you.
I got a JLog1, which I don't use right now and it could find it's way into an envelope to Knoxville and be used there for 'testing" purposes for a while. . .

Hey, does this look like clutter??

[mkovalcson]

Here's the thing.

I'm sorry to say it, but I'm not really worried about how fast the blades are turning.

The TDR makes a different pitch with each change in rpm, but otherwise flies very consistantly.

I do care about vibrations and I have all the info I need there. I know my BEC circuit is working great and I have nice long flight times and my batteries are coming back with plenty of juice left.

If I happen to be running 1600 rpm at 60%, I actually don't care. The heli flies fantastic!

Or it did this morning

I don't know the exact speed my Protos or T550 is running either. Does it really matter?

[DT75]

I don't know exact HS either. I've set 4 flatlines (35-45-55-60%, ATV 100/100), and fly for the most part at 45% and 55%. Tached it with a Skytach early on, but can't remember the results exactly anymore...

I will use the same values when setting up the Diabolo, as they work so great in the TDR, and decide which motor pinion to use after the maiden.

Will probably tach 'em sometime during the summer, but mostly just to have an idea, not to hunt for exact rpm's.

[mkovalcson]

LOL

A few TDR owners get Diabolos and we get good feedback and suddenly we are all getting in line

Of course when people own and fly a TDR and then really like a Diabolo and think they are built as well as a TDR but with a different personality, it really says a lot!

I guess we just have a mutual admiration society over here!

Still I'm giving myself a whole season before I buy another helicopter...

[SimStream]

Yeh sorry, I think I must have read groucho's post about the SK gov and presumed you used it too. My mistake

Originally Posted by mkovalcson

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.

[mkovalcson]

After tearing my TDR down I found out that I had to order a BLS 251 gearset as well, so I added a hyperion V2 tach sensor to that order.

[helizen]

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.

Is SL working for you or is it still the same situation?

[mkovalcson]

Originally Posted by helizen

Is SL working for you or is it still the same situation?

Self leveling is working fine for me at 60% throttle and I haven't seen it come down with any vibration alarms.

Now if I could just get their Data Viewer software to work again! I haven't been able to look at it since I installed a Hyperion v2 tach sensor.

[desertstalker]

No reason SL shouldnt work on a TDR, people have it working fine on a Trex700 at 2100+RPM so...

[Groucho_]

Originally Posted by desertstalker

No reason SL shouldnt work on a TDR, people have it working fine on a Trex700 at 2100+RPM so...

Actually there is a reason... Vibrations...

I have them shoot up at anything over 1450 RPMs from zero to around three at 1550 and over ten at 1700.

SL switches off at 1700...

I'll be restricting myself to 1350, 1450 & 1550 RPMs as my headspeeds.

[NRPY]

Strange. Do you know where the vibes are coming from (which frequency)? Have you tried shimming the backlash in that one gear that mkovalcson was talking about? He said it had a significant effect on his vibe scores.

[Groucho_]

They're from the tail-side of the heli.

Mostly the tail boom and the torque tube and bearings within.

Apparently high vibes on this machine are normal according to some owners who posted about this here. Even Jan himself told me that this is normal... Essentially I believe that the heli wasn't built to pass self-levelling vibration criteria, it just needed to be able to play well with the V-Bar or other FBL gyros. Which it does perfectly.

I was surprised that even removing the tail boom support struts lessened the vibrations... I also moved the torque tube bearings around quite a bit. The readings varied substantially with each sequence. The best I found was to have all three bearings equally spaced - using the measurements in the old manual for the outer two bearings, with the third between them.

Still, you can see the tail fin vibrating. I don't like seeing that...

[NRPY]

Is it possible to move the SK to another location, far away from the tailboom? It might be worth investigating. Perhaps a custom gyro mount somewhere up front? I don't have mine yet, so I'm not sure what the frame layout looks like.

[Groucho_]

I agree with your line of thinking...

The way to fix this is through better mounting.

Unfortunately the TDR's gyro mounting plate is located in what is arguably the worst place on any helicopter - At the point where the tail boom joins up with the body...

I've mitigated the effects of the vibrations, and their ability to bother the SK-720 somewhat by using Allign PU gel and a metal plate for mounting the gyro to the plate. I get good results at lower vibrations with this, but the gel and metal plate can only do so much, and don't do much at all at the higher RPMs I mentioned.

I suppose that the gyro could be mounted at the front, using an extended ESC tray - which I already have. This would however entail a complete rewiring of the servo cables from the back to the front.

I am loathe to do this unless I have proof positive that it actually works though...

[mkovalcson]

Groucho,

I'm getting head speed 1530 at 48% throttle and 1666 at 60% throttle

From what I can see giving it a 90% collective peak at 60% throttle resulted in 48 rpm dip and a 90% collective peak at 48% throttle resulted in 32 rpm dip.

Since my rebuild I'm running slightly higher vibs, but I think after a few more flights things will smooth down a bit.

At 60% throttle I'm currently getting about 6.3g's with a few peaks at about 7g's.
I think that I should be able to get that down to mid 5's.

I can tell you that I used the auto level at 60% throttle the other day and it worked.

I want to do a bit more testing, but I can see that right now 1700 or so would probably put it well into no bailout territory.

[NRPY]

Originally Posted by Groucho_

I agree with your line of thinking...

I suppose that the gyro could be mounted at the front, using an extended ESC tray - which I already have. This would however entail a complete rewiring of the servo cables from the back to the front.

I am loathe to do this unless I have proof positive that it actually works though...

I'm wondering about this (without having a TDR to look at). If you mounted a power bus where the SK-720 is currently located, it seems like all your servo, ESC, and BEC wires wouldn't need to be re-routed because you could just connect them to the power bus instead of the SK-720 itself. Then you would just need to run the 3 patch cables from the power bus to where ever you end up mounting the SK-720; thus minimizing the necessary re-wiring. What do you think?

Tell me more about this extended ESC tray. Any pics? Is it available from Henseleit, or is it a custom part. If it's a readily available part, I'll be the guinea pig for testing when my TDR arrives.

[Groucho_]

Originally Posted by NRPY

If you mounted a power bus where the SK-720 is currently located, it seems like all your servo, ESC, and BEC wires wouldn't need to be re-routed because you could just connect them to the power bus instead of the SK-720 itself.

Yes, that is one way of going about it.

Though if it did work in getting the vibes lower, one would maybe want to go ahead and redo the cable runs eliminating the powerbus and routing everything directly to the front.

Originally Posted by NRPY

Tell me more about this extended ESC tray.

Here's the link for the tray: http://www.cr-modelltechnik.de/rizub.htm

It's not perfect. Ideally there'd be another set of holes milled for the cable ties, and some larger holes for the esc cables to pass through.