450 Is training gear causing my crashes?

[Mda1701d]

Hello all,
After spending all weekend going right through all the setup again on the 450L, and replacing yet another stripped tail drive gear set, all is still not well.
I went right through the DIR again, swash is now dead level high, low and mid. All blade pitches checked and CG perfect.
Spooled up again tonight to check, and still the heli wants to tip when on the ground, if left for more than about 10 seconds. So I tried to pop it up a bit sooner, with throttle lowered to about 40%, but the heli is instantly unstable and cant be corrected in time before yet another tail strike, and more stripped gears.
I wonder if its the training gear upsetting the gyro (3GX ver 4) and causing more problems than it is helping.
Does anyone else have a veiw on this, or any more ideas?? I know many people say that training gear cant be used on these, I would worry that it will go over the minute I spool without now. Im going to order one more set of gears, then give up I think.
Thanks for any help,
Mark

 

[Dirk]

I can guarantee you that the training gear is not the problem. I used training gear on my 450 DFC when I learned to fly.

I see two problems. One is your 3GX is on version 4, which is an absolute DOG on the tail! Most of us have reverted back to Version 3.1 I think. Secondly, the 3GX does NOT like being on the ground. They tend to tip the heli over if kept on the ground, and seeing that you are keeping the heli on the ground for ten seconds you are really the 3GX off.

Is your tail compensating in the correct direction? Have a look at Lee's how to on checking gyro compensation direction.

Hang in there, between all of us we'll get it sorted.

 

[Admiral]

Hi Mda1701d
I maidened a 450 yesterday and yes they the 3GX does not like training gear, I use a hoop rather than the traditional training gear but I have found that no 3 Axis gyro likes the influence of the additional weight and the normal training gear is even worse because all four legs can vibrate independently. I had issues other than using the 3GX that I wanted to test so I used the hoop but only lifted off an inch or two at the most, when I was sure everything was going OK I removed the hoop and had a good maiden. BTW it still had a slight tendency to want to tip I normally stabilize on the ground under power then lift away quickly.

 

[Mda1701d]

Hey, Thanks for the words Dirk.
Your comments on the 3GX all seem right. After more than a few seconds spooling (just after mid stick has been reached, with me being nervous and raising slowly) the heli tries to tip. It can be compensated, but the manual warns against this.
I checked the tail again at the weekend, Lee's vid is great for this, very clear, all seems correct on mine.
I also spent a long time making sure it was smooth, and the servo horn at 90, as well as the control rod travel dead centre.
Its very disappointing, after spending hours and months on the Phoenix sim, I can hover, land in the centre of the target evey time, loop, roll, hover inverted and almost cut the grass!! Yet can't even spend 2 seconds in the air in real life!!
I looked back at the vid we did of the first time I hopped it up, with no training gear, and even though it was a windy day, and moved around alot, it looked stable.
I wonder if trying some bigger landing skids would be the answer? Maybe from a 500??

 

[Admiral]

There we have both views, I have the tail issues on my 500 but not on the 450's, and yes they hate being on the ground.

 

[Mda1701d]

Thanks for the comments Admiral!!
I had slightly more success with the welding wire gear I made for a start, but decided it was too heavy.
This thing is awfully scary whirling sideways, four angry yellow balls and a massive strimmer!!!!!
Anyone got any uses for stripped gears?? I got loads of them now!!!!

 

[Admiral]

No use for stripped umbrella gears, but it may ease the problem if you stick a foam ball off your training gear on the bottom of your vertical stabilizer.

 

[Dirk]

Going with bigger landing gear is a good idea. The training gear that I used consisted of 4 carbon tubes with small white balls on the ends. Weighs nothing.

I think you must zap some 500 gear on there.

Keep us posted.

 

[Mda1701d]

The traing gear i have has 4 carbon sticks with big angry yellow balls on the end. Was supposed to be for a 450. The bin men can have it now! It doesnt seem very heavy, but it must add to the momentum of the heli, and also vibrations.500 landing skids will be the next thing to try i think.

 

[Slobberdog]

If your training gear gives you a vibe it will be a nightmare for the 3gx, I have 3 3gx units on my heli's, and the only tip over I have had is because I had used end point adjustment in my radio to limit servo travel,

 

[Mda1701d]

Interesting slobberdog.....
I think all my travels are set at 100% but they go to 125 on spektrum? Do you think this could be a problem? I am trying to upload a vid of some hops i tried a few weeks ago when it seemed a bit more stable

 

[Lee]

Does it always try to tip the same way?
I'm guessing to the left.
What I have noticed with training gear.
When the heli becomes light on the skids, it starts to drift left. As all helis do.
The training gear obviously stops the heli from tipping to the left, but the 3GX sees this as a unintentional command.
It therefore fights against the training gear, and eventually wins the battle, and the heli tips over.
If this is the case. Holding a touch of right aileron while spooling up may help.
It may not, but it could be worth a try.

 

[Slobberdog]

I would recommend leaving all your end points at 100% and don't move them,

Then I don't like the training gear on the smaller heli's they always shake as they are never thick or heavy, but it is the best thing to have if you are not comfortable with getting the heli off the ground and keeping it in the air.

That being said the 3Gx is a sensitive soul and quite temperamental to being left on the ground with vibration, V4 was supposed to cure that but I hated it on my 450 so went back to 3.1 which I like, and have not got v4 on any of my birds either,

+1 to what Lee said, once you get the heli light on the training gear balls it's ok to use cyclic input as the heli thinks its in the air.

 

[Mda1701d]

Thanks chaps!
It seems to try to tip to the left at first as you say Lee, but then there seems to be a compensation as it goes light, and certainly last night it tipped wildly to the right. All happened in a split second, and didnt get more than a foot off the ground. More gears stripped.
I have posted a vid of the first time I spooled up and hopped in the garden, here....
Trex dominator first hops - YouTube

At this point, I didnt have training gear, so I made a small frame from alloy welding wire to increase the footprint. I wasn't too happy with it though, as it was quite heavy. The heli didnt show any of the signs of trying to tip over like it does now, but it was quite windy on the day.
One more thought I had was that my 3GX is underneath, so very close to the centre point of the training gear.
I've ordered the 500 skids, and yet more gears, so I'll try again. If, however I'm wrong, and the heli flys as it does now without the gear, then its problem solved anyway, because it will be in a million bits on the floor!!
Thanks for the help all!!

 

[Slobberdog]

The Heli looked good in the video as you say try it without the training gear if you can, also it might have been said if you can try not to touch the cyclic until it's off the ground, that will help with the gyro not trying to fight your inputs, it's a good idea to try the 500 undercarriage as well as the bigger footprint it brings the tail and tail blades further off the ground, which might help with blade strikes,

 

[Lee]

Looked fine in the video.
I def think it was the training gear fighting the gyro on lift off.
500 skids are the way to go.

 

[treff]

I would definitely put 500 skids on you 450. I have them on 2 of mine and when learning will save you a lot 0f heart ache also as suggested put one of those yellow foam balls of your training gear onto the vertical fin at the rear. This will take out the sting
of any tail landings. Good luck.

 

[danhampson]

When I first got my 450 I put 500 skids and vertical fin on.

The vertical fin stops tail blade strikes and stripped tail gears.

 

[Sparse]

on aside note as i have been told the 3gx should be level at mid stick, and not the whole range of travel. the 3gx will get confused because its trying to adjust for things not being level. you need to be level at mid stick and let the 3gx do its job. and i never used version 4 to many horror stories. hope this help. john salt writes really informative pdf books, for swash setup. and all sorts of heli stuff and ccpm setup. look him up and have a read. www. rc helicopter fun.com

 

[Mda1701d]

Hi sparse,
Thanks for your comments. I wonder if you could please clarify a bit about your meaning of 3gx being level at mid stick....
I have 0 pitch at mid, maybe you refer to this? I now have 500 skids on, ready to try, just need a calm day. Cheers, mark.