Crash - minor damage, but want opinions

[aamacgregor]

A couple of weeks ago I crashed my 130X while attempting to do a roll (my first outside of Phoenix) while exiting a figure-8, basically the heli dropped and hit the ground. It was a bit windy at the time, and the 130X wasn't all that high off the ground (a little over 5ft) - I assumed that the wind might have caught it a little and that in addition I'd had a dumb-thumb moment on the pitch control. I was quite pleased that there was no damage.

Today, I was out again with the 130X and thought that I'd have a go at hovering inverted (again a little over 5ft off the ground), however, as soon as I inverted it, it started dropping rapidly even though I was applying the appropriate amount of negative pitch on the stick - I tried to save it by applying full negative pitch, but it still kept dropping so I attempted to get it upright but didn't have the room and unfortunately planted it tail first into the ground. This time, there was no mechanical damage but the tail fin had snapped.

I was curious as to why I wasn't getting any lift by applying negative pitch, so when I got home I thought I'd have a little look, and this is what I found:

1) Full negative equates to 0 degrees pitch (when the flight mode is set to Idle Up).
2) There appeared to be some exponent in the pitch control just like the pitch curve I had set up for when the flight mode is set to Normal.
3) Point 2 had me thinking, so I checked the pitch curves for Normal and Idle Up
- Normal has the curved pitch curve as I specified when setting it up
- Idle Up has a linear pitch curve (-100 to +100), however, flicking the f-mode switch (Normal->Idle Up) strangely does not affect the pitch response on the 130X instead, both positions follow the pitch curve assigned to Normal instead but the throttle curve does change - linear when f-mode = Normal; and a flat 100% when f-mode = Idle Up).

I'm kind of at a loss as to why the pitch curve for Idle Up is not getting applied when I flick the switch to the Idle Up position when the throttle curve does get applied. Any thoughts you have on this matter would be much appreciated (DX7s).

Anyway, now something is broken, I'm looking at getting a carbon tail fin, but figure that if I'm paying for postage, then I may as well buy something else too, however, I don't want to spend too much money. These are the things that are currently on my long term upgrade list:

a) Metal gears
b) Lynx blade grips
c) Lynx tail slider
d) Lynx tail blade grips

I'm thinking that either the tail slider or the tail blade grips would be the highest priority (I have noticed that there is play in both which is probably why the tail isn't holding as it should under pitch pumps... maybe). Anyway, if you could only get one of the above upgrades, which one would you get?

As always, your input is always appreciated.

[PaulJC]

Get the metal 'a' tail gear and metal pitch slide, they are the 'need' parts really and an 'o' ring kit

I've never used a DX7 but assume it's similar to the 6/8, do you have to assign the pitch curves to the individual IU modes as well as the throttle, if you have the 130x powered up and at low stick (disconnect the motor), there should be an obvious change in pitch as you flick to IU if your modes and curves are set as per the manual

[kylelnsn]

Get the metal 'a' tail gear and metal pitch slide, they are the 'need' parts really and an 'o' ring kit

Your list is good already and with Paul's additions you would be onto a winner for sure!! Pitch slider is a great addition

[aamacgregor]

Get the metal 'a' tail gear and metal pitch slide, they are the 'need' parts really and an 'o' ring kit

Options 'a' and 'c' it is then. I have the O ring kit already, but haven't put them on yet.

I've never used a DX7 but assume it's similar to the 6/8, do you have to assign the pitch curves to the individual IU modes as well as the throttle, if you have the 130x powered up and at low stick (disconnect the motor), there should be an obvious change in pitch as you flick to IU if your modes and curves are set as per the manual

Yes you have to apply the pitch curves to the individual flight modes for each model. The DX7s only has two flight modes (Normal and Idle Up). As mentioned in my original post for the 130X I have the pitch curve for Normal set to a curve (the one suggested by the manual) and for Idle Up it is set to linear from -100 to +100. Flicking the f-mode switch to Idle Up does not apply the Idle Up settings for the pitch curve (when at low stick the pitch is zero degrees), but does apply the throttle curve for Idle Up. I find this behaviour weird, surely it should either apply both pitch and throttle curves, or if I hadn't set up the f-mode switch properly, neither?

[aamacgregor]

Your list is good already and with Paul's additions you would be onto a winner for sure!! Pitch slider is a great addition

You'll have an order coming your way shortly.

[Paz26181]

Have you set the fm switch to be your IU on your tx or is IU set to another switch?

[aamacgregor]

Yes the F-Mode switch is set to Flight Mode.

[PaulJC]

Well i've just quickly downloaded the DX7 manual and it doesn't seem there is any special requirements for the pitch curves to be activated in idle up, maybe if you do some screen shots of your curve set up might aid in someone being able to help

[tomatwalden]

I was curious as to why I wasn't getting any lift by applying negative pitch, so when I got home I thought I'd have a little look, and this is what I found:

1) Full negative equates to 0 degrees pitch (when the flight mode is set to Idle Up)....

As always, your input is always appreciated.

From point (1), sounds like you don't have zero-pitch set correctly. The 130x (in stock setup) has little markers on the main head and blade grips to allow you to set zero pitch.

Recently, I had very poor positive climb out, but ballistic negative climb out. Took three turns of all cyclic links to sort it out ...

[aamacgregor]

Firstly thanks PaulJC for your spot on diagnosis - I have now got to the bottom of the problem.

The fact is, I was being stupid! As it turns out, I hadn't put the stick low and clicked the f-mode switch (even though I was convinced I had) to compare the pitch at low stick. What I had actually done, is put the stick to low looked at the rotor blade pitch (roughly), put it back to middle, switched it to Idle Up and then put it to low stick and checked the rotor blade pitch again, at which point I thought that the pitch looked to be the same as before and therefore assumed that the same pitch curve was being applied to both settings. For some strange reason, what I had failed to notice is that when the stick is low in Normal mode, the rotor blades actually had a couple of degrees of positive pitch, and when set to Idle Up, the rotor blades had a couple of degrees of negative pitch. It was only after thinking about PaulJC's post that I actually left the stick at low and clicked the switch back and forth and thought to myself "That is kind of embarrassing! Not only is the pitch not zero as I had been reporting, but there is a significant change between Normal and Idle Up!".

In short, the reason why the 130X has been dropping when inverted is because the amount of available negative pitch has only been two degrees or so, and that has not been enough. So, now I have taken a proper look at the pitch of the rotor blades and it looks like rather than having a pitch of something like -10/+10 it has something like -2/+18 with centre stick being something like a whopping +6 degrees! Clearly I hadn't bothered doing a proper check of the set up yet before flying it after taking it out the box - lesson learned! The massive positive pitch would also explain why the tail isn't holding when the stick is at maximum positive in a pitch pump. So it looks like it hasn't been set up properly at the factory.

I'll pop the links off the swash plate and give them a few turns to bring centre stick down to zero degrees (and put the new 'O' rings on while I'm at it). So thank you, for your support.

[aamacgregor]

From point (1), sounds like you don't have zero-pitch set correctly. The 130x (in stock setup) has little markers on the main head and blade grips to allow you to set zero pitch.

Recently, I had very poor positive climb out, but ballistic negative climb out. Took three turns of all cyclic links to sort it out ...

You are absolutely correct!

[PaulJC]

The problem is sorted which is the main thing

[tomatwalden]

You are absolutely correct!

It's what I keep telling my wife - she just doesn't believe me ....

[aamacgregor]

The problem is sorted which is the main thing

Yeah and on the positive side, although finding the issue cost me a tail fin, it did give me an excuse to order a couple of upgrades! In the end I didn't see the metal 'A' gear on Kyle's web site (it was there, but I didn't notice it), so I added the Lynx tail blade grips instead of the metal 'A' gear to my order of a carbon tail fin and Lynx tail pitch slider. That said, I'm bound to need some new parts soon, so I'll order the metal 'A' gear when that happens.

It's what I keep telling my wife - she just doesn't believe me ....

Ah, but the wife is always right! My wife will often admit when I'm right and she's wrong, but for times when I'm wrong, I've used the line from Megamind a couple of times "You were right... and I was less right" She's seen the film, so she knows if I say that line, I'm admitting that I'm completely wrong.