Newbie with queries

[flykiwi]

Hi,

This is my first post, just come across this forum and it looks great... sorry for such a long post, but I have been building up a few queries over the last couple of months.

I have an HDX 450... have had a few 'incidents', and have managed to rebuild and get into the air again OK.

First query, I notice that my grub screw on the main shaft collar does not fit the keyed area of the shaft, it is off by a couple of mm (yes, I have the shaft in the right way ).

It has always been this way (brought the Heli near new - second hand). Is this normal for an HDX 450? Not sure what could be wrong.

Next few queries are all about tail rotor issues.

Issue one: After my first 'incident with the ground', I have developed a tail wag. My first incident popped my tail servo apart, so had to get a new one... I put the tail wag down to the servo, but I have since constructed another out of spares, and the wag is still there. Have played around with gyro gain, don't think it is that. Any other common things cause tail wag? (My next queries may be related.) Gryo is a Futaba 240, and servos have been the JR Sport SM 8.

Issue two: How much vibration is too much vibration? I am wondering if this is the problem relating to issue 1 and 3? Seems to be due to tail rotor, have changed shaft, have new bearings on the way.

Issue three: loss of tail rotor authority. Has happened a few times. I think the first couple were due to a ceased bearing. Fixed that. But I have had a couple of times (the last resulting in my most serve crash yet) where, perhaps by bad collective control, getting the rotor rpm too low, the tail has started spinning, first time it happened, I regained control after about 5 or 6 revolutions of the heli, and everything seemed fine... on the next battery... it happened again and I did not regain control...

In order to try and fix issue 1, I went to the new plastic tail rotor pulley as there was room for the pulley to move left and right on the shaft by about .5-1mm. I notice the new one has 11 teeth where as my aluminum one had 10. I am wondering if this was enough to reduce tail rotor effectiveness at low rpm?

I am considering putting on the front pulley on the tail, because it seems to be a bit tighter there. Anyone know of any issues with this? Belt alignment is my main concern.

In other posts I have read about slowing down the tail rotor, why would you want to do that? Just curious.

Well, once again, apologies for such a long post, I was thinking of spreading them out, but am keen to get back in the air .

Thanks for any help.
Regards
Colin

[RotoN3D]

Colin,

Sounds like you got allot going on here. There are many ideas to remidies for your issues not all pointing to any particular part of the heli. So I suggest especially getting this heli second hand, you need to start over with all the basic adjustments in the head, tail, gyro, everything. If you are a newbie and I can say that I am as well to learn about your basic setup by watching Finless Bob videos on the HDX 450 and locate the gyro tutorial as well and start fresh.

Regards,

R3D

[flykiwi]

Hi, thanks for the reply.

A bit more details about the heli's history... the helicopter was second hand, but very new, only a couple of flights (supposedly... it looked pretty new, no signs of wear and tear anywhere).

When I received it, it came with a DVD of Finless's videos... very useful! (Have since downloaded more!)

I re-setup the head (it needed it, the previous owner obviously didn't watch the videos!), tail and pretty much everything in-between.

In terms of the main shaft key being seemingly in the wrong place for the grub screws, I can't see how any change could be made to bring it to the right place, other than the collar having a longer flange on the bottom.

Do other peoples grub screw go into the keyed area of the shaft?

As for where to start on the tail, yep, you are right, a lot going on, and I have no idea...

Thing is it was good before my first crash, so can't blame the heli's history for that. The shaft has been changed since also.

One thing I am unsure on is how much vibration is there allowed to be? I know you want as little as possible, but how little?

When feeling the stabilizers, you get a numb feeling from the vibrations, is this OK? Is any visible vibrations of the stabilizers acceptable?

I have new bearings on the way, so shall put them in and see if it makes a difference but I imagine the current bearings have had very little use. Have balanced the tail rotor blades, but still have some vibration there.

Regards
Colin

[RotoN3D]

Colin,

Make sure you can hover your heli with little or no tail drift with the switch on your gyro turned off. That is part of the first steps in setting up a gyro. When you initialize the gyro making sure when you power it up your heli doesn't get bumped or moved in the process. Wait a few seconds and if your gyro is working and set up properly you should have a rock solid tail more obediant than a canine cop. As far as the vibes, check tail blade balance or bent tail shaft.

Regards,

R3D

[flykiwi]

Hi R3D,

I did go through the gyro setup initially, but I guess a fair bit has changed since, so shall give it another go... only problem is it might take me a day or two... just starting to learn how to do loops, have done about 7.5 so far :( (you know the feeling when you think you should stop, calm the nerves... but keep going anyway?... Got to learn to listen to myself more often, kept it at 7 loops instead of 7.5!)

So shall go through the re-setup process, including the gyro, and see how it goes... Still not sure it is gyro related because sometimes when I flick up to mode 1 and pick up the revs, the twitching tends to lessen a bit.

But shall do the setup again and see what happens... shall post back in a couple of days.

Thanks
Colin

[PTFlyer]

I had a simmilar problem with my tail at one point.......couldn't figure it out.......changed servo's then went so far as a new gyro.....all after checking and changing the gears for the tail.......

after the last un wanted piro/ near wreck I decided to check the last link, the one way bearing.....it seemed fine, but upon closer look the bearing collar had a grove worn in it, this allowed the bearing to not lock up all the time...whne adding power it would slip.....changed the bearing (just in case) and the collar and I haven't had it happen again


not sure if this is your problem but worth a look........

also the main shaft......I know you said it is installed the correct way........but just for giggles I'd flip it and see if the grove then lines up with the collar grub....again...worth a shot.

[mx101]

I am also a newbie with an HDX450, I have had a couple crashes but have since put many flights on it without any issue. Upon receiving new main shafts from HD I noticed that the new ones have an extra key way cut just above the bigger one? Not sure why but the the new smaller key way is in the correct position. Same place as the Align main shaft. As for the tail rotor I also had significant vibration due to having the belt to loose. When I tightened up a little the vibration dropped to near nil. I was also able to greatly reduce the gain on the gyro.

Steve

[flykiwi]

Interesting... so the one way bearing seemed to cause some tail wag?

I am in the process of replacing the main bearings, they seem quite gritty, so who knows, maybe that will help.

As for the main shaft, yip, flipped it and then the groove is way off. I am currently using align shafts as they are a bit easier to come by here, the current align shafts have an 'Align' text engraved on them, and this sets in between the two shaft bearings.

Even in pieces I can't see how it could go back together and have the key in the right place for the main shaft collar grub screw. The grub screw ends up straddling the key and non key parts of the shaft.

Do other people have this alignment of the shaft?

By the way, the key in the HDX and Align shafts are in exactly the same places (at least in the shafts I have had from Helidirect).

Regards
Colin

[flykiwi]

Hi Steve,

Just to confirm, so when you use your new shaft you use the key that is in exactly the same place as the Align shaft?

When I use HD or Align shafts (I use Align now because they are cheaper), my grub screw always goes half over the key and half over the non keyed area of the shaft. Probably holds worse being half and half rather than not at all, but have not had any problems with it coming loose (yet!)

Interesting about the belt, I never know how tight it should be, but think I have it reasonably tight.

Colin

[MiniCwik]

I had a similar issue with my hybrid T-Rex/HDX 450 SE but resolved it.

I have the STK superframe in my T-Rex, and use the all Aluminum head from HeliDrect which is the same head in the HDX kit.

What is needed is a taller collar, the one that goes above the main gear, as mine was also not lining up. Once I got the new collar from HeliDirect, all lined up fine and all was resolved. It also helped space down the main gear as it was so tight to the frame.

Here is a link to it - http://www.helidirect.com/product_info.php?products_id=1360 read the one posted review.

[Rogerdee]

Converted my 2 SEs to STK Superframes.

These is the gears I use:
http://www.helidirect.com/product_info.php?cPath=250&products_id=1455
This is the 106T(Not 109T) which slows the tail rotor.
No problems with Align mainshafts but you MUST use the Helidirect thicker spacer between the main gear and bearing.
I noticed that 2 of the standard align spacers are almost the same thickness ?Have not tried as I have enough thicker spacers.
Also,use the metal Align tail rotor shaft/pinion and remove the idler pulley on the tail case.

Roger 0274314632

[flykiwi]

I think I have the right lower collar, the one that came with the Helidirect autorotation sleeves.

Also, the tail gears seem to line up reasonably well. I actually just brought Align gears as Helidirect don't seem to be doing the original main gears anymore... which meant I also needed to buy a new hub... which I thought I would also need a new Align auto rotation sleeve... turns out, as you say, the align sleeve and collar are too small, still need to use the HDX sleeve and collar.

However, after all that, on the top collar, the grub screw still seems to be 'missing' the keyed area, or at least ending up directly over the change from non keyed to keyed area. I am wondering if there is another version of the collar around? It is almost like the same distance out as if you were using the small lower collar, but I am reasonably sure I am not (because the tail gears line up, and it is definitely bigger than the Align one).

Regards
Colin

[flykiwi]

Hi Roger,

So your grub screw on the top goes into the keyed area of the main shaft?

Also a query about the gears... I have read a couple of posts about slowing the tail rotor... I have the 106T gear, just wondering what the reason is people want to slow the tail rotor, I thought faster would be better.

Another reason I ask is that I have the new plastic version 2 tail gear and shaft which is 11 tooth rather than 10, which I guess also slows the tail rotor down 10% or so.
With it on I have had a couple of times where I loose tail rotor control after probably loosing too much head speed... just wondering if the plastic 11 tooth gear is a good thing or not.

So you use the Align tail rotor shaft and pinion in an HDX tail rotor assembly? Had a quick look at this as I have quite a few tail issues at the moment, but the space for the gear in the tail rotor assembly seemed bigger than the Align one, so thought the gear and shaft would have too much movement... but maybe I did not look hard enough.

I see you are another kiwi flyer :-) I was beginning to wonder if I was the only kiwi with HDX parts... glad I am not :-)

Regards
Colin

[jcc]

I just purchased a new and assembled HDX450SE-V3. This heli is fully assembled and has been hovered. It includes 3 Hitec HS-56HB servos and 1 Hitec HS-5245MG on the tail, a GY401, Castle Creations Phoenix 45 controller, and a Castle Link USB programmer. It also came with a new Thunder Power 2070 mah/11.1v battery and an E-station BC5 balance charger.

I have a DX6 and an AR6000. I'm waiting on my Phoenix Simulator to arrive where I will practice before I fly.

So, I am open to any tips that you can give me.

Jesse

[Rototerrier]

I have 10 years of RC Air experience and only about 6 months of heli. I can do flips and rolls and combinations of the 2...ie: very limited 3D. I would be nowhere near where I am without my prior air experience. I you have never flown anything, then I would suggest starting out flying planes on the sim. Learn forward flight and normal stick orientations first. Once you can fly a plane you can quickly pick up forward flight of a heli. Once a heli is in forward motion, the controls are exactly like an airplane, you just have to control the rudder...where a plane you can get away with only Ail and Elev. Helis are much harder, but soooooooo much more fun once it clicks.

But, if you have flown before, then learn to hover tail in on the sim and then get a really nice set of training gear for your heli and go for it. I stumbled across this a while back in my continuing quest for learning 3D. http://www.heliguy.com/nexus/learning.html

Some pretty good advice on getting started. Give it a read, it will help.

Happy flying and welcome to the family.

[Rogerdee]

Hi again Colin,
Changed a mainshaft yesterday-Align-and the screw lined up spot on.

Tail rotor speed-many posts about this-do a search-tail rotor speed was way to high.

I dont have the HDX tail assembly as I converted my SE-I have an Align tail assembly on one and a Copterx on the other-no problems.

Good luck

Roger