TDR Technical Stuff (Tips) & Build Videos

[helicraze]

2009 head, flies better in FFF
2010 head, flies worse in FFF (Pitch up easy)

2009 head can wobble at 1600RPM, at any other RPM its ok just 1600RPM.

All my friends convert to 2009 head as it feels more precise and quick to respond and better in FFF.

You english is very good.

[Heli G]

Originally Posted by helicraze

Since i flew the 09 version for 6 months before i got my 10 version, the 09 version is much better in all aspects IMHO (only if you fly at 1600RPM you get a wobble).

The 10 version pitches easily in FFF

HC, I haven’t tried the 2009 head at all but didn’t find the 2010 head to pitch up at all, whether in forward flight or very fast forward flight. Was there a specific head speed you found this and with which blades? Am currently running 1700 and 1850 with Radix standard 710mm and Jan's white blades – max pitch is 13 deg, but I have my new TDR setup for 14 deg’s and will also be flying the Radix FBL 710’s as soon as the weather allows.

[helicraze]

This was at 1850RPM and 14 deg pitch with standard radix blades, if you get enough speed you will see what i mean

[aussiemick]

Originally Posted by helicraze

This was at 1850RPM and 14 deg pitch with standard radix blades, if you get enough speed you will see what i mean

I don't get the pitch up at full speed (and yes, it is going very fast).

I run about 1900Headspeed and 14.5' collective in speed flying mode, I have the cyclic backed off to about 6', I run Radix 710 FBL blades.

The elevator function does get a bit touchy but with expo and reduced rates then it flies flat out from one end of the field to the other without any input at all from me.

Maybe you didnt have the VBar setup spot on when you tried the 2010 head out....????

Mick

[jointer]

I think it might be also blades.
You mean the heli in FFF will behave like if you added pitch, but you did not?
I do not fly much very fast FF, but i did not noticed anything like this at medium speed.
And i have my CoG bit at front.
But when i tried Torsion blades, they "bite" in the air during fast loops or turns, similar like if you added pitch fast.

[helicraze]

Adding heavier blades and more RPM and less cyclic will make it less pronunced.

Fly the 2010 head if you like it, i fly both and there are different behaviours in flight, myself and others prefer the 2009 non rocking type.

[chilau]

Is it easy to convert the 2010 head to the 2009 non rocking type, read in a earlier post that you can put a sleeve on the feathering shaft to take out the rocking.
I did similar a mod on the Srimok to stiffen the head up.

[Heli G]

Originally Posted by chilau

Is it easy to convert the 2010 head to the 2009 non rocking type, read in a earlier post that you can put a sleeve on the feathering shaft to take out the rocking.
I did similar a mod on the Srimok to stiffen the head up.

HC will be able to explain better, but I believe the 2010 black spindle bushing (0109) allows for play (0.2mm) so the spindle has a small amount of “teetering”, whereas the 2009 white spindle bushing does not have any play.

[g-bru]

Is it a case of simply replacing the black bushings with the white ones, therefore not having to replace the whole hub?

G.


Sent from my iPhone using Tapatalk

[jointer]

G-bru, yes, you need JUST the white bushings.
You can even use the hard o-rings which comes with the 2010, but expect the head will be very stiff, so i get now front-back tail wag under 1400RPM and ugly shake in hover at 1600-1700RPM.

[helicraze]

Yep replace the black bush with the white one, and remove the set screw that holds the spindle, its not needed. Flies nicer IMHO

[g-bru]

Ok fellas, thanks.

Will swop them out for the white bushes if I find the flight characteristics not to my liking.

G.

[jointer]

By my short experience, you get more aglility and more precise control with 2009.
But my feeling is you need also to control the heli more then with 2010.
For relaxed flights, 2010 head might be better, there is anyway some difference.

[majicjohnson]

You guys don't think with your speeds with this machine you are getting retreating blade stall. An area near the hub and tip start to stall and max effect at 9.00 position acting 90 degrees later Heli will pitch up. Different blade types and pitch will effect this. Also Inc head speed will help as well. Just a thought, no other Heli would get close to the speeds to suffer this but maybe just maybe the TDR does.

MJ

[aussiemick]

If my calcs are correct the tip speed of the blades is 603kmh, at 2000 headspeed.
Take off the 250kmh of full speed (only possible in a dive) and the retreating tip is still going at 350kmh.

The inside 300mm of the retreating blade would be going slower than the helis airspeed, and so yes that part of the blade would not be lifting.

I reckon the FBL controller is seeing this pitch up tendency and adjusts the swash accordingly. For a FB heli this would be a heap bigger issue as for a FBL heli.

Mick

[majicjohnson]

There is a bit more to it than just tip speed.

The advancing blade will be tip speed plus forward speed and the retreating blade will be less forward air speed.

We know lift formula is lift=Cl1/2RhoV2S (So velocity squared in this case for now), the advancing blade will naturally generate more lift if uncorrected so we have flapping to compensate for Dissymetry of lift. The advancing blade will flap up reducing AofA through increasing induced flow and retreating side will flap down increasing AofA.

There will come a point where aerodynamics just won't keep up with what is required to balance out and the retreating side tip will stall whilst the reverse flow of the inbound section increases with increasing forward speed.

So we approach what we know as retreating blade stall, to overcome we are told 3 things: reduce power (pitch), increase rpm if we can or reduce forward airspeed. Generally if not the heli will pitch up and have a tendency to roll to the retreating side.

This is prob worth a thread on its own but when I see at 14 degrees pitch not 12 and this is happening with a change in hub design I just wonder if this is what is going on.

MJ

[Vinger]

Originally Posted by majicjohnson

There is a bit more to it than just tip speed.

The advancing blade will be tip speed plus forward speed and the retreating blade will be less forward air speed.

We know lift formula is lift=Cl1/2RhoV2S (So velocity squared in this case for now), the advancing blade will naturally generate more lift if uncorrected so we have flapping to compensate for Dissymetry of lift. The advancing blade will flap up reducing AofA through increasing induced flow and retreating side will flap down increasing AofA.

There will come a point where aerodynamics just won't keep up with what is required to balance out and the retreating side tip will stall whilst the reverse flow of the inbound section increases with increasing forward speed.

So we approach what we know as retreating blade stall, to overcome we are told 3 things: reduce power (pitch), increase rpm if we can or reduce forward airspeed. Generally if not the heli will pitch up and have a tendency to roll to the retreating side.

This is prob worth a thread on its own but when I see at 14 degrees pitch not 12 and this is happening with a change in hub design I just wonder if this is what is going on.

MJ

You have to figure in the lead/lagging of the blades as well. IOT to balance lift across the disc, the advancing blade lags, giving it effectively less lift and when the blade reaches the retreating side it moves from lagging to leading, effectively increasing relative flow as well as increasing lift by straightening out.

That's the biggest contributor to getting the lift equal on RC helicopters as we use very rigid heads which allows for minimal flapping.

[majicjohnson]

I think you have lead/lag the wrong way around. Lead/lag is a direct result of flapping. Flapping isn't just mechanical the actual blade will flex as well. As a blade flaps up (advancing side) the cofg moves towards the centre of rotation so it wants to accelerate (lead). Other conditions may cause this such as changes in drag, hooks law. Clasic example, ice scater spinning arms out slow, pulls arms in speeds up.

My point was that with a hub design change it could have changed the characteristics of the machine and different bladed, pitch settings as some have described have helped which makes sense.

I'm not going to go in to anymore aerodynamics as it's starting to hijack the thread. A great read is Wagdendonk. It's almost the first book you read when becoming a Commercial Helicopter Pilot.

MJ

[JiriK]

Could you guys post pictures of your TDR battery mounting setups?

I just received my second pair of Turnigy nano 6s4000 45c packs and I´m going to to make a "stick" out of them.

I´ll be using these packs in a Logo600se (as my TDR is still months away) but I´d prefer to be able to use the same packs in both helicopters.. Currently using some plastic Align battery trays in logo.

[aussiemick]

I don't have pictures of my packs but I can say they are just a long stick pack

I joined the 2 6S packs together with 1mm thick fibreglass strips, a strip 40mm wide and 300mm long on either side of the 2 packs.
I then lengthened the power wires and the balance taps.
Lastly heat-shrink over the whole lot, there are now two sets of power leads and balance taps coming out the front of the "stick".
You just have to be sure that you know which balance tap belongs to which set of power leads.

Mick