First crash questions

[Sean U.]

Well it finally happened; I had my first crash with my Hawk Sport
(third flight without training gear). I don't feel so bad because I
feel that I'm well overdue for my first crash at 15hrs and about 57
flights (flying figure 8s pretty well, starting to work on nose in
turn figure 8s). Even though officially it is my first crash it was
not really due to pilot error. The battery went low and the throttle
went to idle at about 20ft, I think this is a feature/warning on the
Futaba 9C that you better land now. I have had this happen before, but
I was very near the ground and the throttle came back after landing
and going to full low stick (reset). Unfortunately it landed a little
faster and harder than I wanted. I tried to auto it on the way down
but don't think I gave it enough, or any, negative collective. It hit
the ground a little nose in and broke the front landing strut and tail
strike. The blade that hit the tail only has a small dent in the
leading edge and a groove in the trailing edge near the grip where it
hit the blade holder, after swinging around from the tail strike.
Other than those issues a normal crash kit should fix everything. Here
are my questions:

1) On the 9C, when the throttle goes to idle, from low battery, do I
have all other control and does it take going to full low throttle to
reset throttle control? It all happened so fast, I thought I was
controlling it, but not sure.

2) When performing an auto, do I need to get into negative collective
to keep rotor speed up before giving positive collective?

3) Could the blade tightness have made it easier for them to strike
the tail? I think they were a little too loose. If they were tighter
would they have hit the tail or would it have lead to more blade
damage?

4) Can I still use the same blades? One has a small dent in the
leading edge, but otherwise seems good.

I'll get it fixed this next week and get it back in the air.

Thanks for the help in answering my questions.

Sean

[Sean U.]

Can anyone give me a hand with these questions?

Thanks,

Sean

[Joe Bill]

"Sean U." <sulrich@surewest.net> wrote in message
news:498ac7cd.0408272140.22563532@posting.google.c om...
>
> 1) On the 9C, when the throttle goes to idle, from low battery, do I
> have all other control and does it take going to full low throttle to
> reset throttle control? It all happened so fast, I thought I was
> controlling it, but not sure.
>
This one's tough to answer as most people quit flying long before the low
battery alert goes off. You're the first person I've heard of who's gone
into that no-man's land. But I would venture a guess that you're gonna lose
all channels equally due to low battery, and this is a dangerous situation
as you effectively can lose control altogether. I'd recommend developing
the habit of stopping around 9.0v before the 9C alert goes off at 8.5v (I
expect the voltage roll-off once it gets down to 9.0v is pretty fast so you
may not even have 10 minutes for it to drop to 8.5v). Not sure what going
to full low throttle would have to do with "resetting" anything.

> 2) When performing an auto, do I need to get into negative collective
> to keep rotor speed up before giving positive collective?

I'm by no means an expert on autos and still practice them at the end of
every flight and occasionally bounce one off the ground due to not flaring
soon enough (or too soon). But typically I go to full negative pitch while
in throttle-hold (roughly -3 degrees) to help get it down near the ground
while I still have head-speed to play with. I fly a Raptor 50 w/600mm
blades, but have heard the Raptor 30 with its 550mm blades are a whole lot
harder to auto due to less energy in the blades. I would expect a Hawk
(30-sized) to have the same issues.

The book "The Basics of Radio Control Helicopters" says that you need more
than -2 degrees negative pitch to be able to keep the head-speed up on the
descent, and that you need more than +8 degrees of positive pitch to arrest
the fall for landing. It recommends a pitch range of -3 to +12 for autos,
although it cautions to be careful with +12 if flying with the engine as
that may overload the engine and bog it down.

But, when you're not planning to do autos, then you try and make-do with
what you've got. On the 2 or 3 unplanned autos I've done, I've done them in
idle-up 2 (where I normally fly) with -9 to +9 pitch, so I have consciously
remembered to only go about halfway on negative pitch as otherwise I'll
plummet to the ground too fast and probably flare too late and bounce.
>
> 3) Could the blade tightness have made it easier for them to strike
> the tail? I think they were a little too loose. If they were tighter
> would they have hit the tail or would it have lead to more blade
> damage?
>

The main blades being too loose is generally thought of as the #1 cause of
boom strikes, although any time the heli body hits the ground with speed
you're likely to have the main blades flex down and a boom strike is likely
(I know - I've done this about 5 times). The general rule of thumb is that
if you extend the blades out and then turn the helicopter over on its side
and the blades stay in place, then they're tight enough. You can generally
avoid boom strikes by not hitting the ground :) although I had an in-air
boom strike once that looked and sounded like I'd had a mid-air collision
with someone. Never could figure out the cause.

> 4) Can I still use the same blades? One has a small dent in the
> leading edge, but otherwise seems good.

You don't say if you're using woodies or carbons or fiberglass, but in
general everything I've seen says replace the blades after a crash,
especially if you've had a boom strike, as you don't know what structural
damage you've done to them and you don't want them shredding on you on the
next flight when they're spinning at 1800 rpms.

>
> I'll get it fixed this next week and get it back in the air.
>
> Thanks for the help in answering my questions.
>
> Sean
>

[Tim]

Joe Bill wrote:
<snip>
>
> This one's tough to answer as most people quit flying long before the
> low battery alert goes off. You're the first person I've heard of
> who's gone into that no-man's land.
>
<snip>

I had a similar thing happen when my Rx battery dipped below the cut-off
voltage set on my GV-1 governor. The GV-1 dropped the revs to a preset (low)
position and the heli started coming down. It took me a few seconds to
realise what was going on, but fortunately, the rotor speed was still enough
to let me bring the model down gently, though it was a long way away from
me! I'm more diligent at keeping an eye on the battery checker now...

Tim


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[Steve R.]

Hi Joe & Sean,

"Joe Bill" <joebill@swbell.net> wrote in message
news:F8SYc.7513$ju3.5334@newssvr23.news.prodigy.co m...
>
> "Sean U." <sulrich@surewest.net> wrote in message
> news:498ac7cd.0408272140.22563532@posting.google.c om...
>>
>> 1) On the 9C, when the throttle goes to idle, from low battery, do I
>> have all other control and does it take going to full low throttle to
>> reset throttle control? It all happened so fast, I thought I was
>> controlling it, but not sure.
>>
> This one's tough to answer as most people quit flying long before the low
> battery alert goes off. You're the first person I've heard of who's gone
> into that no-man's land. But I would venture a guess that you're gonna
> lose
> all channels equally due to low battery, and this is a dangerous situation
> as you effectively can lose control altogether. I'd recommend developing
> the habit of stopping around 9.0v before the 9C alert goes off at 8.5v (I
> expect the voltage roll-off once it gets down to 9.0v is pretty fast so
> you
> may not even have 10 minutes for it to drop to 8.5v). Not sure what going
> to full low throttle would have to do with "resetting" anything.
>
I've flown a 9Z radio since 1995. I've taken my helicopter down to the
battery fail safe one time. You know, flying all day, BSing with the guys,
and loose track of how many flights I've had. My helicopter also had a GV-1
on it at the time. When the engine cut to idle, I thought it had quit so I
flipped throttle hold and auto'd down with no problems. I had full control
of the model at all times. When I walked out to get it, the engine was
sitting there, happily idling along. I flipped off the throttle hold, added
power and brought her back into a hover which lasted about 30 seconds before
the throttle dropped to idle again. "That's" when I figured out what the
problem was. :-o I shut down everything and sure enough, the flight
battery was almost fully drained. I count that as a free helicopter! Thank
you very much, Mr. Futaba! :-)

Joe, Futaba radios that have the battery fail safe come programmed to idle
the throttle when the voltage dropped below a predetermined point. When
this happens, if the pilot lowers the throttle stick to idle position and
brings it back up again, the system will let you have throttle again for
about 30 seconds and then cut back to idle. It's supposed to give the pilot
the time to put the bird on the ground before the entire flight system shuts
down from lack of voltage. In my case, it saved my helicopter. Believe me,
I have no illusions but that I was VERY lucky that day but the battery fail
safe obviously worked in my case. I "wouldn't" recommend trying this
yourself! ;-)

FWIW!
Fly Safe,
Steve R.

[Mark]

> >> 1) On the 9C, when the throttle goes to idle, from low battery, do I
> >> have all other control and does it take going to full low throttle to
> >> reset throttle control? It all happened so fast, I thought I was
> >> controlling it, but not sure.
> >>


> and loose track of how many flights I've had. My helicopter also had a
GV-1
> on it at the time. When the engine cut to idle, I thought it had quit so
I
> flipped throttle hold and auto'd down with no problems. I had full
control
> of the model at all times. When I walked out to get it, the engine was
> sitting there, happily idling along. I flipped off the throttle hold,
added
> power and brought her back into a hover which lasted about 30 seconds
before
> the throttle dropped to idle again. "

> Joe, Futaba radios that have the battery fail safe come programmed to idle
> the throttle when the voltage dropped below a predetermined point. When
> this happens, if the pilot lowers the throttle stick to idle position and
> brings it back up again, the system will let you have throttle again for
> about 30 seconds and then cut back to idle.

The Futaba Battery failsafe moves the throttle to the position that you have
set when you set up the failsafe. It doesn't automatically set it to idle.
YOU have to program the failsafe settings correctly. This is most important
for helicopters. By default, all channels are set to Hold I think. So on
loss of signal or a flat battery, the throttle will stay where it was unless
you have set the failsafe properly. Obviously, Sean did . So in answer to
his question, When the throttle goes to the failsafe set point from low
battery, Yes, you lower the stick to that set point or below and that resets
it, to give you another 30 seconds or so ( as Steve said ) of throttle
control until it trips again.

Mark H

[Beav]

"Joe Bill" <joebill@swbell.net> wrote in message
news:F8SYc.7513$ju3.5334@newssvr23.news.prodigy.co m...
>
> "Sean U." <sulrich@surewest.net> wrote in message
> news:498ac7cd.0408272140.22563532@posting.google.c om...
> >
> > 1) On the 9C, when the throttle goes to idle, from low battery, do I
> > have all other control and does it take going to full low throttle to
> > reset throttle control? It all happened so fast, I thought I was
> > controlling it, but not sure.
> >
> This one's tough to answer as most people quit flying long before the low
> battery alert goes off.

Not so tough. When the battery low point closes the throttle, closing the
throttle manuallly will re-engage the control and NONE of the other cntrols
are affected. Closing the throttle will allow you to open it and throttle
the motor back up again too, and everything is fine for 30 seconds. Then it
closes the throttle again.

The first time it does it is a good indicator to get that machine on the
floor NOW.


You're the first person I've heard of who's gone
> into that no-man's land. But I would venture a guess that you're gonna
lose
> all channels equally due to low battery,

Not on the Futaba. The "throttle closed" is a warning before the final
death.

and this is a dangerous situation
> as you effectively can lose control altogether. I'd recommend developing
> the habit of stopping around 9.0v before the 9C alert goes off at 8.5v (I
> expect the voltage roll-off once it gets down to 9.0v is pretty fast so
you
> may not even have 10 minutes for it to drop to 8.5v).

If the batteries are Nicads, the drop in voltage is still quite slow, unlike
the drop off in pwer from a NiMih. they hold voltage for longer, but when
they start to drop, they REALLY drop.

Not sure what going
> to full low throttle would have to do with "resetting" anything.

It does exactly that. The Rx shuts the throttle, but closing it at the Tx
end allows it to be re-opened, but only for half a minute before the cycle
begins again. This has been a feature of high end Futaba's since the late
80's starting with their first PCM set.

>
> > 2) When performing an auto, do I need to get into negative collective
> > to keep rotor speed up before giving positive collective?

Yes. Around -3 is plenty too. Any more than -3 and the descent rate is hard
to control and any less and the blade speed is hard to maintain.

>
> I'm by no means an expert on autos and still practice them at the end of
> every flight and occasionally bounce one off the ground due to not flaring
> soon enough (or too soon). But typically I go to full negative pitch
while
> in throttle-hold (roughly -3 degrees) to help get it down near the ground
> while I still have head-speed to play with. I fly a Raptor 50 w/600mm
> blades, but have heard the Raptor 30 with its 550mm blades are a whole lot
> harder to auto due to less energy in the blades. I would expect a Hawk
> (30-sized) to have the same issues.
>
> The book "The Basics of Radio Control Helicopters" says that you need more
> than -2 degrees negative pitch to be able to keep the head-speed up on the
> descent, and that you need more than +8 degrees of positive pitch to
arrest
> the fall for landing.

I'd agree with the negative pitch values, but the positive should be as much
as you can get. You CAN manage with 8 degrees, but it requires good
management at the end to get it down without damage if you don't have an
excess of pitch available.

It recommends a pitch range of -3 to +12 for autos,

Perfect for learning auto's.

> although it cautions to be careful with +12 if flying with the engine as
> that may overload the engine and bog it down.

You can't drive 12 degrees, but you don't ever need to. The pitch curve for
auto's is completely independent of any of the other pitch curves, so you
set each curve accordingly.

>
> But, when you're not planning to do autos, then you try and make-do with
> what you've got. On the 2 or 3 unplanned autos I've done, I've done them
in
> idle-up 2 (where I normally fly) with -9 to +9 pitch, so I have
consciously
> remembered to only go about halfway on negative pitch as otherwise I'll
> plummet to the ground too fast and probably flare too late and bounce.
> >
> > 3) Could the blade tightness have made it easier for them to strike
> > the tail? I think they were a little too loose. If they were tighter
> > would they have hit the tail or would it have lead to more blade
> > damage?
> >
>
> The main blades being too loose is generally thought of as the #1 cause of
> boom strikes,

Actually, the number one cause of boom strikes at the end of an auto is the
amount of back stick held in when the skids contact the ground. If there's
ANY back stick held in, you're buying a new back end. the last thing a flyer
should do before they touch down at the end of an auto, is to puh a TINY
amount of forwards stick in. That completely eliminates the possiblilty of
having any back stick in, and the worst that will happen is the heli slides
on instead of stopping. (dead)

although any time the heli body hits the ground with speed
> you're likely to have the main blades flex down and a boom strike is
likely
> (I know - I've done this about 5 times). The general rule of thumb is
that
> if you extend the blades out and then turn the helicopter over on its side
> and the blades stay in place, then they're tight enough. You can
generally
> avoid boom strikes by not hitting the ground :) although I had an in-air
> boom strike once that looked and sounded like I'd had a mid-air collision
> with someone. Never could figure out the cause.

THAT was likely due to having the blades too loose in the grips and having a
lot of positive pitch in causing the blades to lag too much. Just sit yur
heli on the bench and put full pitch in, then fold the blades. It won't take
long 'til one blade is under the horizontal stabiliser.


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk

[Steve R.]

Mark, you are absolutely correct on that point. We have to program the set
points.

In my case, I just got lucky because I don't remember specifically setting
anything with regards to the battery fail safe. It happened to go to a nice
comfortable idle, all on it's own.

I guess it's better to be lucky than good! :-)

Fly Safe,
Steve R.


"Mark" <mark.hutching.remove.this@xtra.co.nz> wrote in message
news:z4qZc.20601$N77.856611@news.xtra.co.nz...
>
> The Futaba Battery failsafe moves the throttle to the position that you
> have
> set when you set up the failsafe. It doesn't automatically set it to idle.
> YOU have to program the failsafe settings correctly. This is most
> important
> for helicopters. By default, all channels are set to Hold I think. So on
> loss of signal or a flat battery, the throttle will stay where it was
> unless
> you have set the failsafe properly. Obviously, Sean did . So in answer to
> his question, When the throttle goes to the failsafe set point from low
> battery, Yes, you lower the stick to that set point or below and that
> resets
> it, to give you another 30 seconds or so ( as Steve said ) of throttle
> control until it trips again.
>
> Mark H
>
>

[RECKLESS LOONY]

On Thu, 02 Sep 2004 02:21:59 GMT, "Steve R."
<srhodes13@houston.rr.nospam.com> wrote:


>
>In my case, I just got lucky because I don't remember specifically setting
>anything with regards to the battery fail safe. It happened to go to a nice
>comfortable idle, all on it's own.

It is a feature if the PCM Rx and it cannot be disabled.



Reckless Loony
More reckless and loonier than ever Muhahaha !!

>
>Fly Safe,
>Steve R.
>

[Kevin R]

"Mark" <mark.hutching.remove.this@xtra.co.nz> wrote in message
news:z4qZc.20601$N77.856611@news.xtra.co.nz...
>> >> 1) On the 9C, when the throttle goes to idle, from low battery, do I
>> >> have all other control and does it take going to full low throttle to
>> >> reset throttle control? It all happened so fast, I thought I was
>> >> controlling it, but not sure.
>> >>
>
>
>> and loose track of how many flights I've had. My helicopter also had a
> GV-1
>> on it at the time. When the engine cut to idle, I thought it had quit so
> I
>> flipped throttle hold and auto'd down with no problems. I had full
> control
>> of the model at all times. When I walked out to get it, the engine was
>> sitting there, happily idling along. I flipped off the throttle hold,
> added
>> power and brought her back into a hover which lasted about 30 seconds
> before
>> the throttle dropped to idle again. "
>
>> Joe, Futaba radios that have the battery fail safe come programmed to
>> idle
>> the throttle when the voltage dropped below a predetermined point. When
>> this happens, if the pilot lowers the throttle stick to idle position and
>> brings it back up again, the system will let you have throttle again for
>> about 30 seconds and then cut back to idle.
>
> The Futaba Battery failsafe moves the throttle to the position that you
> have
> set when you set up the failsafe. It doesn't automatically set it to idle.
> YOU have to program the failsafe settings correctly. This is most
> important
> for helicopters. By default, all channels are set to Hold I think. So on
> loss of signal or a flat battery, the throttle will stay where it was
> unless
> you have set the failsafe properly. Obviously, Sean did . So in answer to
> his question, When the throttle goes to the failsafe set point from low
> battery, Yes, you lower the stick to that set point or below and that
> resets
> it, to give you another 30 seconds or so ( as Steve said ) of throttle
> control until it trips again.
>
> Mark H
>
Mark you cannot set the low battery warning its built in on the receiver
have a look at this from Futaba, I know this states for a 6X but as its a
receiver function this can happen on any set with the right receiver

What is 'battery failsafe'? What does this mean? How does it work?
Battery failsafe is an automatic safety function of the 6X Super computer
radio. When the receiver's battery voltage drops below a predetermined cut
off (approximately 3.8v) and remains there for more than a set amount of
time (several seconds - this allows for occasional hard drains caused by
violent maneuvers such as snaps which immediately returns the voltage back
to above 3.8v), the receiver recognizes that you are in a dangerous
condition, and brings your throttle servo to a high idle. This is a warning
that you must safely retrieve the model (land for aircraft/helicopters), as
you are reaching a point where there will not be sufficient voltage to
operate the receiver.

How does it work? The transmitter periodically sends commands to the
receiver that are to be used in the event of a failsafe situation. When the
receiver determines a failsafe situation is occurring, it obeys these stored
commands. In a battery failsafe situation it obeys only the throttle command
but obeys regular transmitter commands for all other channels. It continues
to analyze the transmitter's commands for throttle, and when the transmitter
command is the one set as the 'reset' for the failsafe is received then it
releases the failsafe hold on throttle.

As an additional safety of this feature, you can pull your throttle stick to
idle and readvance it, allowing you to use power to return the model to you,
and you will have throttle control for approximately 30 seconds before the
feature reactivates, returning the throttle to high idle. IT IS IMPERATIVE
THAT YOU LAND OR OTHERWISE RETRIEVE YOUR MODEL IMMEDIATELY BEFORE LOSING
CONTROL OF THE MODEL

[Kevin R]

"Kevin R" <dontemailme@ntlworld.com> wrote in message
news:xhi0d.115$3x4.25@newsfe2-gui.ntli.net...
>
> "Mark" <mark.hutching.remove.this@xtra.co.nz> wrote in message
> news:z4qZc.20601$N77.856611@news.xtra.co.nz...
>>> >> 1) On the 9C, when the throttle goes to idle, from low battery, do I
>>> >> have all other control and does it take going to full low throttle to
>>> >> reset throttle control? It all happened so fast, I thought I was
>>> >> controlling it, but not sure.
>>> >>
>>
>>
>>> and loose track of how many flights I've had. My helicopter also had a
>> GV-1
>>> on it at the time. When the engine cut to idle, I thought it had quit
>>> so
>> I
>>> flipped throttle hold and auto'd down with no problems. I had full
>> control
>>> of the model at all times. When I walked out to get it, the engine was
>>> sitting there, happily idling along. I flipped off the throttle hold,
>> added
>>> power and brought her back into a hover which lasted about 30 seconds
>> before
>>> the throttle dropped to idle again. "
>>
>>> Joe, Futaba radios that have the battery fail safe come programmed to
>>> idle
>>> the throttle when the voltage dropped below a predetermined point. When
>>> this happens, if the pilot lowers the throttle stick to idle position
>>> and
>>> brings it back up again, the system will let you have throttle again for
>>> about 30 seconds and then cut back to idle.
>>
>> The Futaba Battery failsafe moves the throttle to the position that you
>> have
>> set when you set up the failsafe. It doesn't automatically set it to
>> idle.
>> YOU have to program the failsafe settings correctly. This is most
>> important
>> for helicopters. By default, all channels are set to Hold I think. So on
>> loss of signal or a flat battery, the throttle will stay where it was
>> unless
>> you have set the failsafe properly. Obviously, Sean did . So in answer to
>> his question, When the throttle goes to the failsafe set point from low
>> battery, Yes, you lower the stick to that set point or below and that
>> resets
>> it, to give you another 30 seconds or so ( as Steve said ) of throttle
>> control until it trips again.
>>
>> Mark H
>>
> Mark you cannot set the low battery warning its built in on the receiver
> have a look at this from Futaba, I know this states for a 6X but as its a
> receiver function this can happen on any set with the right receiver
>
> What is 'battery failsafe'? What does this mean? How does it work?
> Battery failsafe is an automatic safety function of the 6X Super computer
> radio. When the receiver's battery voltage drops below a predetermined cut
> off (approximately 3.8v) and remains there for more than a set amount of
> time (several seconds - this allows for occasional hard drains caused by
> violent maneuvers such as snaps which immediately returns the voltage back
> to above 3.8v), the receiver recognizes that you are in a dangerous
> condition, and brings your throttle servo to a high idle. This is a
> warning that you must safely retrieve the model (land for
> aircraft/helicopters), as you are reaching a point where there will not be
> sufficient voltage to operate the receiver.
>
> How does it work? The transmitter periodically sends commands to the
> receiver that are to be used in the event of a failsafe situation. When
> the receiver determines a failsafe situation is occurring, it obeys these
> stored commands. In a battery failsafe situation it obeys only the
> throttle command but obeys regular transmitter commands for all other
> channels. It continues to analyze the transmitter's commands for throttle,
> and when the transmitter command is the one set as the 'reset' for the
> failsafe is received then it releases the failsafe hold on throttle.
>
> As an additional safety of this feature, you can pull your throttle stick
> to idle and readvance it, allowing you to use power to return the model to
> you, and you will have throttle control for approximately 30 seconds
> before the feature reactivates, returning the throttle to high idle. IT IS
> IMPERATIVE THAT YOU LAND OR OTHERWISE RETRIEVE YOUR MODEL IMMEDIATELY
> BEFORE LOSING CONTROL OF THE MODEL
Just found this
Battery failsafe is an automatic safety function of the 9Z computer radio.
When the receiver's battery voltage drops below a predetermined cut off
(approximately 3.8v) and remains there for more than a set amount of time
(several seconds - this allows for occasional hard drains caused by violent
maneuvers such as snaps which immediately