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Servo power?

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markzoom@digiverse.net - 15 Nov 2006 11:46 GMT
What size servos should I use for a 90", high wing, 25cc  gas/petrol
trainer/camera plane?
STOL, Mildly aerobatic.

Servo Types
Standard          : about 3.3 KG/cm torque
Medium torque : BB 5 to 6 KG/cm torque
High Torque     : over 10KG/cm torque

Does this sound about right as the *minimum*?:

Throttle                          --- Standard
Ailerons (a servo each) ---  BB medium torque
Rudder (+tailwheel)       --- BB Medium Torque
Elevator                         --- BB medium torque
Flaps                             --- High Torque (or 1 BB medium for
each flap)

Also, Is one 6V (5cell nimh)  2300 mah battery pack enough ?
Jarhead - 15 Nov 2006 15:23 GMT
| What size servos should I use for a 90", high wing, 25cc  gas/petrol
| trainer/camera plane?
[quoted text clipped - 15 lines]
|
| Also, Is one 6V (5cell nimh)  2300 mah battery pack enough ?

80 inch Robinhood, (Curtis Robin stand off scale) that I bashed by
removing the dihedral, beefing up the spars with spruce along with using
hardwood in the cabin area, plus adding flaps and functional struts.

I used,  T-Standard, A-BB Med, R-BB Hi, E-BB Hi, F-BB Med for each flap.

A 1400Mah NiCad battery has been sufficient for 10 years. ( The packs
started out C size and are now AA size for the same capacity) I started
out with a BB medium torque on the rudder but it didn't last long flying
off of grass as well as pavement.

BTW it is powered by an OS BGX-3500 (2.1 CI)

Signature

Jarhead

markzoom@digiverse.net - 15 Nov 2006 16:17 GMT
> | What size servos should I use for a 90", high wing, 25cc  gas/petrol
> | trainer/camera plane?
[quoted text clipped - 31 lines]
> --
> Jarhead

Okeydokey, thanks for giving me a rough idea.

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Ted Campanelli - 15 Nov 2006 16:29 GMT
Ted shuffled out of his cave and grunted these great (and sometimes not
so great) words of knowledge:

Here you go.  Plug the information in and it will tell you what you
need.  There are also several other nice calculators there.

http://www.csd.net/~cgadd/eflight/calcs_servo.htm

> What size servos should I use for a 90", high wing, 25cc  gas/petrol
> trainer/camera plane?
[quoted text clipped - 15 lines]
>
> Also, Is one 6V (5cell nimh)  2300 mah battery pack enough ?
markzoom@digiverse.net - 15 Nov 2006 19:01 GMT
> Ted shuffled out of his cave and grunted these great (and sometimes not
> so great) words of knowledge:
[quoted text clipped - 3 lines]
>
> http://www.csd.net/~cgadd/eflight/calcs_servo.htm

Nice one!

> > What size servos should I use for a 90", high wing, 25cc  gas/petrol
> > trainer/camera plane?
[quoted text clipped - 15 lines]
> >
> > Also, Is one 6V (5cell nimh)  2300 mah battery pack enough ?
Random Excess - 15 Nov 2006 18:01 GMT
>What size servos should I use for a 90", high wing, 25cc  gas/petrol
>trainer/camera plane?
>STOL, Mildly aerobatic.

 I dunno, but I strongly believe that any and all "camera" planes
should be electric powered because electric motors don't vibrate a
fraction as much as IC engines, especially gasoline ones, and you have
the option to eliminate vibration completely by turning the motor off
during a photo run, and then restarting it.

Tejas Pedro
Doug McLaren - 15 Nov 2006 18:34 GMT
| >What size servos should I use for a 90", high wing, 25cc  gas/petrol
| >trainer/camera plane?
[quoted text clipped - 5 lines]
| the option to eliminate vibration completely by turning the motor off
| during a photo run, and then restarting it.

That would be ideal, yes, but the electric equivilent of a 25cc gas
engine would cost a bundle.

Like it or not, above a certain size, going electric costs a lot more
than going glow or gas.  Things are certainly improving, but the cost
difference is still pretty signifigant, and it gets worse if you
already have all the gas/glow support equipment you need, but don't
have the electric support equipment.

As an example, I'm currently assembling an Ultrastick 25e.  Motor =
$90, ESC = $115, a single battery pack is around $130, though I'm
cheating a bit by going with emoli cells I've already got.  Setting up
a similar glow setup for this plane would cost $80 for the engine, $10
for a servo and $10 for a gas tank -- and this is still a small plane
by glow standards.

(On a side note, I'm really impressed with this ARF, though I haven't
flown it yet.  I'll bet if I had all my tools ready to go, ESC all
soldered up, battery pack ready to go, I could have assembled it in a
single hour.  No glueing needed whatsoever!)

Signature

Doug McLaren, dougmc@frenzied.us
The earth is like a tiny grain of sand, only much, much heavier.

The Natural Philosopher - 15 Nov 2006 18:41 GMT
> | >What size servos should I use for a 90", high wing, 25cc  gas/petrol
> | >trainer/camera plane?
[quoted text clipped - 8 lines]
> That would be ideal, yes, but the electric equivilent of a 25cc gas
> engine would cost a bundle.

So build something smaller.
markzoom@digiverse.net - 15 Nov 2006 19:29 GMT
> | >What size servos should I use for a 90", high wing, 25cc  gas/petrol
> | >trainer/camera plane?
[quoted text clipped - 30 lines]
> Doug McLaren, dougmc@frenzied.us
> The earth is like a tiny grain of sand, only much, much heavier.

You hit it pretty much on the head. The plane will have to be a
platform for a semi-pro video camera likely to weigh about 2lb. The
engine will be anti-vibration mounted, as will the camera. The plan is
to use it for footage for a travel documentary.

The ultimate challenge is to fly it through a rock arch in some sea
cliffs. It means that I will have to fly it into the arch and set it
for a slight climb and turn when the failsafe kicks in as it loses
radio contact on the other side, it should regain RC contact when it
comes into vision again. I think that would make quite a spectacular
vid (even if it piles into the cliff!).  Obviously I'll film  all the
less risky stuff first....
The Natural Philosopher - 15 Nov 2006 22:32 GMT
>> | >What size servos should I use for a 90", high wing, 25cc  gas/petrol
>> | >trainer/camera plane?
[quoted text clipped - 43 lines]
> vid (even if it piles into the cliff!).  Obviously I'll film  all the
> less risky stuff first....

I could carry 2lb payload on my 200W electric 60" old timer..just.

Certainly a 5lb plane with 350W - an easy sort of cheapish electric
setup could carry 2lb. Something like the venerable senior telemaster is
in that ball park. Power train about $200
markzoom@digiverse.net - 16 Nov 2006 09:58 GMT
> >> | >What size servos should I use for a 90", high wing, 25cc  gas/petrol
> >> | >trainer/camera plane?
[quoted text clipped - 49 lines]
> setup could carry 2lb. Something like the venerable senior telemaster is
> in that ball park. Power train about $200

The brand new strimmer engine cost me ?30 ($50 US)

It needs to be STOL, fly in windy conditions, cope with turbulence and
be able to carry floats as well, with a decent climb rate. The video
camera may need to be on a tilt-swivel mount.
I already have small electric and glow planes (glow is out because the
fuel is unobtainable)
I can always fork out for a big electric setup at a later stage, but
right now this is the cheapest and favourite option.
The thing is, the locals there might get interested in building some,
and strimmer engines are widely and cheaply available. Conversly,  glow
engines would have to be got mail order and expensive glow fuel would
have to be delivered by ship because it's volatile, lead time 4 weeks.
I'm fed up with glow engines anyway.
Doug McLaren - 19 Nov 2006 15:19 GMT
| The ultimate challenge is to fly it through a rock arch in some sea
| cliffs. It means that I will have to fly it into the arch and set it
| for a slight climb and turn when the failsafe kicks in as it loses
| radio contact on the other side, it should regain RC contact when it
| comes into vision again.

You might not ever lose contact -- the cliff will probably attenuate
the signal greatly, but unless you're really far away enough of it
might still diffract around the cliff to control the plane.

Of course, it's hard to fly a plane you can't see, so ...

| I think that would make quite a spectacular vid (even if it piles
| into the cliff!).  Obviously I'll film all the less risky stuff
| first....

Sounds like a great way to destroy a plane!  Be sure to have somebody
filming on the other side so you can catch the crash!

Signature

Doug McLaren, dougmc@frenzied.us
Only those who dare to fail greatly can ever achieve greatly.
--Robert F. Kennedy

Random Excess - 15 Nov 2006 19:33 GMT
>| >What size servos should I use for a 90", high wing, 25cc  gas/petrol
>| >trainer/camera plane?
[quoted text clipped - 11 lines]
>Like it or not, above a certain size, going electric costs a lot more
>than going glow or gas.

 Do you want good pictures or not?

 Electric motors vibrate less, much less, than IC engines, and can be
turned off and on in flight, a huge advantage especially for quality
minded photogs.  It's laugh out loud funny to me that so many rc'ers
can sink very many hundreds or even thousands of dollars into the
brand new latest hobby gadgetry and yet somehow manage to continue to
gripe out about the cost of electric power.  Guy with a 10K plane and
a 2K radio, "electric is too expensive."  Get real, bro.

>Things are certainly improving, but the cost
>difference is still pretty signifigant, and it gets worse if you
[quoted text clipped - 7 lines]
>for a servo and $10 for a gas tank -- and this is still a small plane
>by glow standards.

 My vision of a camera plane is that of a 100+" span sailplane-like
platform.  "Old" electic flight technology (meaning much less
expensive) motors & batteries would be more than sufficient power.

>(On a side note, I'm really impressed with this ARF, though I haven't
>flown it yet.  I'll bet if I had all my tools ready to go, ESC all
>soldered up, battery pack ready to go, I could have assembled it in a
>single hour.  No glueing needed whatsoever!)

 See?  You're really just another electric fan!  <g>

 Which, btw, I'm not.  I gotta smell that exhaust.  If I ever go all
electric I'll need to have a downwind camp stove nearby boiling glow
fuel.

Tejas Pedro
markzoom@digiverse.net - 15 Nov 2006 20:06 GMT
> >| >What size servos should I use for a 90", high wing, 25cc  gas/petrol
> >| >trainer/camera plane?
[quoted text clipped - 13 lines]
>
>   Do you want good pictures or not?

Of course. Videos, not just pictures.

>   Electric motors vibrate less, much less, than IC engines, and can be
> turned off and on in flight, a huge advantage especially for quality
[quoted text clipped - 3 lines]
> gripe out about the cost of electric power.  Guy with a 10K plane and
> a 2K radio, "electric is too expensive."  Get real, bro.

Sure, but it needs to carry a broadcast quality video cam.

> >Things are certainly improving, but the cost
> >difference is still pretty signifigant, and it gets worse if you
[quoted text clipped - 11 lines]
> platform.  "Old" electic flight technology (meaning much less
> expensive) motors & batteries would be more than sufficient power.

Sure, but it won't carry a 2lb pro video cam, possibly on a swivel-tilt
platform, nor will it cope with windy conditions or flying uphill fast.
You can fit a *still* or even a small consumer video cam onto pretty
much any plane nowdays, but to shoot pro vids where I want to do it,
the plane I'm building is my first choice.

> >(On a side note, I'm really impressed with this ARF, though I haven't
> >flown it yet.  I'll bet if I had all my tools ready to go, ESC all
> >soldered up, battery pack ready to go, I could have assembled it in a
> >single hour.  No glueing needed whatsoever!)
>
>   See?  You're really just another electric fan!  <g>

Lol!
I have 'lectric gliders too and some 400 size own design funplanes. I
prefer peaceful electric to stinky, dirty glow. I left the pull start
on this petrol engine (quite light one) and it starts with two pulls.
No messing with glow batteries and needle valves. The fuel is cheaper
too. Anyway, you can't get glow fuel where I want to film.

>   Which, btw, I'm not.  I gotta smell that exhaust.  If I ever go all
> electric I'll need to have a downwind camp stove nearby boiling glow
> fuel.
>
> Tejas Pedro
The Natural Philosopher - 15 Nov 2006 22:33 GMT
>>> | >What size servos should I use for a 90", high wing, 25cc  gas/petrol
>>> | >trainer/camera plane?
[quoted text clipped - 42 lines]
> Sure, but it won't carry a 2lb pro video cam, possibly on a swivel-tilt
> platform, nor will it cope with windy conditions or flying uphill fast.

You should see some of teh slope sorarers mate! They are FAST as greased
weasel sh.t.

> You can fit a *still* or even a small consumer video cam onto pretty
> much any plane nowdays, but to shoot pro vids where I want to do it,
[quoted text clipped - 18 lines]
>>
>> Tejas Pedro
Random Excess - 16 Nov 2006 14:57 GMT
>Sure, but it won't carry a 2lb pro video cam, possibly on a swivel-tilt
>platform, nor will it cope with windy conditions or flying uphill fast.
>You can fit a *still* or even a small consumer video cam onto pretty
>much any plane nowdays, but to shoot pro vids where I want to do it,
>the plane I'm building is my first choice.

 It sounds like an interesting project.  Good luck and I hope you
have fun with it.

Tejas Pedro
markzoom@digiverse.net - 19 Nov 2006 20:04 GMT
> >Sure, but it won't carry a 2lb pro video cam, possibly on a swivel-tilt
> >platform, nor will it cope with windy conditions or flying uphill fast.
[quoted text clipped - 4 lines]
>   It sounds like an interesting project.  Good luck and I hope you
> have fun with it.

Cheers, I'm already having fun designing the plane.

> Tejas Pedro
Doug McLaren - 15 Nov 2006 20:19 GMT
| >Like it or not, above a certain size, going electric costs a lot more
| >than going glow or gas.
|
|   Do you want good pictures or not?

Of course.  And I want a pony too.

In any event, you can get pretty good pictures with a gas/glow plane
by building in an appropriate vibration daming mechanism into your
camera mount.  Then all you have to worry about is the exhaust from
your engine fouling your camera ...

| minded photogs.  It's laugh out loud funny to me that so many rc'ers
| can sink very many hundreds or even thousands of dollars into the
| brand new latest hobby gadgetry and yet somehow manage to continue to
| gripe out about the cost of electric power.  Guy with a 10K plane and
| a 2K radio, "electric is too expensive."  Get real, bro.

I was thinking more of a $300 plane, $50 radio and $50 camera, but
hey, get real bro.

If you've got $10k to put into a plane, you should be able to get
great results, IC or electric.

| My vision of a camera plane is that of a 100+" span sailplane-like
| platform.  "Old" electic flight technology (meaning much less
| expensive) motors & batteries would be more than sufficient power.

Yes, that would work nicely.  And contrary to what the other poster
said, as long as you watch the CoG carefully, a somewhat high
performance 100+" glider certainly should be able to tolerate another
2 lbs of weight without much trouble, though if you mount the camera
underneath, I wonder about landings without a landing gear -- I guess
you'd want to add one.

| >(On a side note, I'm really impressed with this ARF, though I haven't
| >flown it yet.  I'll bet if I had all my tools ready to go, ESC all
| >soldered up, battery pack ready to go, I could have assembled it in a
| >single hour.  No glueing needed whatsoever!)
|
|   See?  You're really just another electric fan!  <g>

Absolutely.  But I'm not an electric (or glow) fanboy -- I know the
advantages and disadvantages of electric vs. IC.

| Which, btw, I'm not.  I gotta smell that exhaust.  If I ever go all
| electric I'll need to have a downwind camp stove nearby boiling glow
| fuel.

I recall seeing some scents to add to your glow fuel at the R/C car
shop.  Seriously.  I imagine it's only a short matter of time before
somebody makes some nitro-smelling cologne, if it hasn't already been
done.

Signature

Doug McLaren, dougmc@frenzied.us       Nature abhors a vacuum. So does my dog.

Storm's Hamilton - 15 Nov 2006 20:49 GMT
> | >What size servos should I use for a 90", high wing, 25cc  gas/petrol
> | >trainer/camera plane?
[quoted text clipped - 26 lines]
> soldered up, battery pack ready to go, I could have assembled it in a
> single hour.  No glueing needed whatsoever!)

Coincidentally I was in Austin last week at one of the Hobbytowns looking at
that plane,the ultra stick 25e.  I ended up with a Formosa glider which I
will power with existing parts.  Went by the Cedar Park shop(rc cars mostly)
and bought an Evolution 1.0 NX for $150.
mk
H Davis - 15 Nov 2006 23:19 GMT
> That would be ideal, yes, but the electric equivilent of a 25cc gas
> engine would cost a bundle.
[quoted text clipped - 16 lines]
> soldered up, battery pack ready to go, I could have assembled it in a
> single hour.  No glueing needed whatsoever!)

A fellow in our club just maidened the Ultra Stick 25e, and loves it. Of all
of the electrics I've seen, this one is pretty awesome. I know very little
about electrics, but this plane will serve to spur me into learning more
about them. The plane is just dead solid. The guy who has it is not usually
impressed with electrics, but I sense a difference in his attitude with this
one. Of course, he has more motor than he needs on the plane, but it really
performs extremely well with it. I believe he said it is an AXI that is two
steps over the one which he was intially considering.

I'm still sticking with glow for now, but I have ventured into the dark side
in a couple of small ways. We'll see how those "ventures" go.

Harlan
markzoom@digiverse.net - 15 Nov 2006 19:10 GMT
> >What size servos should I use for a 90", high wing, 25cc  gas/petrol
> >trainer/camera plane?
[quoted text clipped - 7 lines]
>
> Tejas Pedro

Yes, I thought about that and might do it electric, but I'm going for
the cheapest option first (The strimmer motor was dead cheap). I can
still use the plane just for fun if it's no good for filming.
The plane will likely have to cope with fairly windy conditions like
high coastal and mountain cliffs. It must also be able to carry floats
as well as a decent video cam.
The Raven - 16 Nov 2006 09:37 GMT
> What size servos should I use for a 90", high wing, 25cc  gas/petrol
> trainer/camera plane?
[quoted text clipped - 15 lines]
>
> Also, Is one 6V (5cell nimh)  2300 mah battery pack enough ?

Having built a low wing plane very similar in spec to what you mention I'd
recommend something around the 10Kg rating. That will be more than adequate
for what you need, and ideal for aerobatics while maintaining a safety
margin.

Do a search for a servo torque calculator. Provide the dimensions, max
deflection, and max airspeed for a control surface and see what comes up.

I used Hitec HS-645MG servos. 7.7Kg at 4.8V (from memory) with almost 10Kg
at 6V.

Watch 5 cell packs as fully charged they could be outputting well over 6V,
enough to give some receivers/servos a bad case of the jitters. I'm using a
2500mah 4.8V pack (NiMh) but haven't done enough flying to see how quick
they run down (battery checker says OK after 3 flights).

Signature

The Raven
http://www.80scartoons.co.uk/batfinkquote.mp3
** Now I will bring chaos to the world!

markzoom@digiverse.net - 16 Nov 2006 10:19 GMT
> > What size servos should I use for a 90", high wing, 25cc  gas/petrol
> > trainer/camera plane?
[quoted text clipped - 20 lines]
> for what you need, and ideal for aerobatics while maintaining a safety
> margin.

Yup, though my plane will be a high winger and of fairly modular build
as I will make what fits in a suitcase here and finish off the rest on
the Island. I can make the whole nose section, apennage, control
surfaces and undercarriage here and assemble the rest of the fuz and
the wings over there.
Incidentally, their main building wood there is Japanese cedar,
selections of which are similar to medium grade balsa. It's also
incredibly cheap.

> Do a search for a servo torque calculator. Provide the dimensions, max
> deflection, and max airspeed for a control surface and see what comes up.

Nice chap kindly posted a link above already, I didn't know there was
such a thing before.

> I used Hitec HS-645MG servos. 7.7Kg at 4.8V (from memory) with almost 10Kg
> at 6V.

I have a couple of the plastic gear 645s, but I'm ordering some cheap
Tower Pro servos from Hong Kong.

> Watch 5 cell packs as fully charged they could be outputting well over 6V,
> enough to give some receivers/servos a bad case of the jitters. I'm using a
> 2500mah 4.8V pack (NiMh) but haven't done enough flying to see how quick
> they run down (battery checker says OK after 3 flights).

I have plenty of 2300mah NiMh AA batteries ready to solder up into
flight packs. I will check the max voltage as you suggest. Leaving them
to settle after charging probably helps.

> --
> The Raven
> http://www.80scartoons.co.uk/batfinkquote.mp3
> ** Now I will bring chaos to the world!
quikjr - 27 Nov 2006 19:18 GMT
I have the Ultra Stick Mini and just bought the Ultra Stick 25e. And on
of the 32 motors to power it.
If the 25e is any where near as aerobatic and fun as the Mini is, i
will be an absolute winner.
EFlite 32 mtr..Phoenix 60 ESC with Ultimate BEC installed for the xtr
servos .. 6-HS225BB servos .. 2- 2s2p 4200 mAh Thunder Power batts i
series (4200 mAh @ 14.8 volts) and a new JR 7202 synthisized radio t
fly it with.
So now .. bring on the wind. And Fun fly contests. Yeeha

--
quikj
 
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