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-   -   Hitec SkyScout CG issue ??? (http://www.Wattflyer.com/forums/showthread.php?t=72856)

bigbob4877z 12-25-2013 08:25 PM

Hitec SkyScout CG issue ???
 
Anyone out there experience an issue using 2200 mah 3s lipo's in the Sky Scout? The rec size uses a 1300 mAH---ALOT LIGHTER ! All my surfaces are aligned dead nut. I installed aileron's into wing's too ! The plane flys like it's tail heavy. When power is on --the nose goes upward & climbs---sometimes ok but --then it like stalls almost when power is backed down. Once I give it down it kinda flops down like nose heavy. The CG in manuel says 85mm behind leadling edge. Iv'e set it at neutral---moved 2300 mah back & forth to change CG to where nose after power is off really flops down.

Maybe characteristic of plane ? I hope not ! I have not tried the 1300 mah yet ?

Thanks
BOB

CHELLIE 12-25-2013 08:33 PM

Hi Bob :) set the CG to 25% back from the front leading edge, forget what the manual says, they are always off, 25% back is a very safe place to start at, check the wings incident too, i like a 0 - 0 incident in my planes, if thats ok, add a little down thrust to the motor by shimming the motor, with the motor at the rear, the tail end of the motor should be pointing down a tad, about 2 to 3 degrees should be fine, try those recommendations one at a time, hope that helps, Chellie

bigbob4877z 12-26-2013 03:04 AM

Sky Scout issue !
 
Chellie --Do you fly one of theses ?

JetPlaneFlyer 12-26-2013 08:32 AM

Bob,

Climbing excessively under power is actually usually a sign of nose heaviness, not tail heaviness. A trully tail heavy plane will dive when you increase power. I know this may appear counter-intuitive but believe me, it's true.

Move the CG rearward in small steps re-trimming the elevator after each step to give level flight at cruise power. As the CG goes back (and you trim the elevator to suit) you will find that the model pitches up less when throttle in increased. When the climbing is acceptable or when the model starts to be twitchy on elevator stop moving the CG.

Setting the CG at 25% is a very rough 'rule of thumb' that on most planes is a safe place to start for the maiden flight, but you are well past the maiden flight stage now, final tweaking of the CG must be by flight testing.

CHELLIE 12-26-2013 09:16 AM

Quote:

Originally Posted by bigbob4877z (Post 935238)
Chellie --Do you fly one of theses ?

I have flown those planes in the past, they are a lot of fun.

solentlife 12-26-2013 09:56 AM

Personally ? I would put the smaller battery in, balance as per book and fly.

One of the problems of increased weight at any end of a 'beam' which a model in effect is, the effect on pitching can become extreme.

My Biplane with much heavier engine than designed but still balanced within CoG recc'd range would rear up when throttle closed. I removed the heavier engine, put the recc'd lighter in and she flew perfect, with CoG in same position.

There are far more factors involved in controlled level flight than just CoG and trim. I agree that most design specs are more to sell a model than to really fly it. Small packs that give too short flights, motors that are marginal power etc. etc. But most will actually fly. It is once you get it to fly, you start to modify or alter to suit your style or wants ...

One area that many trainers / first intermediate planes fall down on as I see .. is main wing incidence. Often it is just a tad too much +ve. Based on the lower power design set-ups. Put a decent power setup in and she climbs. So a quick remedy is to put a piece of card or thin wedge under the trailing edge of wing ... altering until the model flies as you want. Much easier than altering thrust lines of motors.

Nigel

bigbob4877z 12-26-2013 03:11 PM

Thanks everyone ! I'll try the smaller batteries @ neutral cog ! The Manuel does state you can use the 2200 mah size but - flys weird. This plane is pretty s
punky. I've seen several guys flying them at this little field by
my house. One guy put a little bigger motor on his & was flying inverted, did a knife edge, good aileron rolls just not at blinding speeds ! I have a Radio Pro that uses the 1350 mah & the plane is 40 % larger. Less stick time unless is all I got to loose.

Anyone recc a motor to use on this ?

CHELLIE 12-26-2013 08:17 PM

Quote:

Originally Posted by bigbob4877z (Post 935262)
Thanks everyone ! I'll try the smaller batteries @ neutral cog ! The Manuel does state you can use the 2200 mah size but - flys weird. This plane is pretty s
punky. I've seen several guys flying them at this little field by
my house. One guy put a little bigger motor on his & was flying inverted, did a knife edge, good aileron rolls just not at blinding speeds ! I have a Radio Pro that uses the 1350 mah & the plane is 40 % larger. Less stick time unless is all I got to loose.

Anyone recc a motor to use on this ?

your plane is very similar to the easystar, a lot of people like to Hot Rod them :) A few things you can do is to use a stronger motor like the one suggested in the video, the wings need to be braced with carbon fiber tube, some people clip from 5 to 10 inches off the wing tips to make them go really fast,


CHELLIE 12-26-2013 08:19 PM


CHELLIE 12-26-2013 08:34 PM

http://www.rcplanet.com/v/vspfiles/p...RC13210-2T.jpg
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http://www.rcplanet.com/v/vspfiles/t...s/clear1x1.gif http://www.rcplanet.com/v/vspfiles/t...s/clear1x1.gif Technical Specs
http://www.rcplanet.com/v/vspfiles/t...s/clear1x1.gif http://www.rcplanet.com/v/vspfiles/t...s/clear1x1.gif http://www.rcplanet.com/v/vspfiles/t...r_Left_Top.gif http://www.rcplanet.com/v/vspfiles/t...s/clear1x1.gif http://www.rcplanet.com/v/vspfiles/t..._Right_Top.gif http://www.rcplanet.com/v/vspfiles/t...s/clear1x1.gif Aileron: Optional
Assembly Time: Less than 1 Hour
Elevator: Yes
Experience Level: Beginner
Flying Weight: 24.5 oz (695 g)
Fuel Type: Electric
Is Assembly Required: Yes
Motor Size: 235-watt Brushless Outrunner (installed)
Overall Length: 38.6 in (980mm)
Plane Type: Sport Planes
Power Plant Size: 450-480 Electric
Radio: 3+ channel radio system
Recommended Environment: Outdoor
Recommended Motor Battery: 11.1V 3S 1300mAh LiPo
Rudder: Yes
Servos: (2) HS-55 servos (installed)
Speed Control: 18-Amp Brushless (installed)
Wing Area: 372 sq. in. (34.0 sq. dm.)
Wingspan: 54.5 in (1384mm)


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Description Reviews Support The beginner's RC airplane that can fly itself in a completely ready-to-fly version!
Exactly the same airplane as MPX4192 EasyStar, but with everything installed so that it's ready to fly (after you charge it up and attach the wing). 54" wingspan, 35" long, 370 sq. in. wing area, 24 oz. flying weight, 9.4 oz./sq. ft. wing loading. EasyStar has unusually stable flight that's perfect for beginners. It's somewhere between a sailplane (it will thermal) and a sport rc plane. It's very easy to handlaunch and fly. (We have video of a pilot handlaunching EasyStar but NOT holding the transmitter! EasyStar climbs right out - straight.) Beginner's hard landings hardly hurt it because it's made of resilient and repairable "Elapor" foam. Even after many crashes during the learning process, Easy Star will be ready for more where other trainers would be ready for the trash can. The motor and prop are mounted on top so hard landings won't break the prop. For 3 channel control: Rudder, Elevator, Motor control.Technical Specifications:
Length: 35"Wingspan: 54"Flying Weight: 24 oz.Controls: Elevator, Rudder, ThrottleWing Area: 370 sq. in.

solentlife 12-26-2013 08:37 PM

Cor Blimey Guv !!

Chellie - he's got enough trouble flying it now !! ;)

Let's get him up and happy first !! ;););)

Nigel
(suffering severe withdrawal symptoms from RC at moment !)

CHELLIE 12-26-2013 08:39 PM


CHELLIE 12-26-2013 09:56 PM

Quote:

Originally Posted by solentlife (Post 935276)
Cor Blimey Guv !!

Chellie - he's got enough trouble flying it now !! ;)

Let's get him up and happy first !! ;););)

Nigel
(suffering severe withdrawal symptoms from RC at moment !)

:D :D :D LOL Just letting him know that he will not outgrow that plane for some time, its fun to Hot Rod those planes :ws:

JetPlaneFlyer 12-26-2013 09:59 PM

Quote:

Originally Posted by solentlife (Post 935276)
Let's get him up and happy first !! ;););)

+1.. I think it's best to get to grips with the model in standard trim before you think about souping it up. Walk before you run;)

bigbob4877z 12-27-2013 02:55 AM

Sky Scout trim issue !
 
Well went out today---sucks 80 deg today--no wind--sun to my back. I used the smaller battery--1350 mah eflite battery. I pretty much got the same results---climbs when using full throttle. Once I backed off at midrange --seemed to fly ok---had 3-4 clicks down trim on elevator though--battery all the way forward to neutral cog !

Maybe characteristic of plane? Has good loop tracking--did split "s" perfect. I just have to have even more down to keep nose down to penetrate. I did try to move smaller battery back from very front 1/2 in or so--got worse ?

any one got anything else to try----Hobby shop advised me a customer put a 1/4 oz weight on tail ?

. It could use a little more power too. I'm used to my Quickie 500 sport--had OS 46 FSR ABC w/muffled tuned pipe on it---screamed. I converted it to electric w/32 eflite motor w/60amp esc--4s---not as fast as nitro though. Guys at the field always balked at it--"too noisy"--but was muffled tuned pipe---measured at 89 db--legal--used to tick them off.

I used to fly at a school--30-40 mins the "law" would show up !



thanks bob

CHELLIE 12-27-2013 06:33 AM

Quote:

Originally Posted by bigbob4877z (Post 935321)
Well went out today---sucks 80 deg today--no wind--sun to my back. I used the smaller battery--1350 mah eflite battery. I pretty much got the same results---climbs when using full throttle. Once I backed off at midrange --seemed to fly ok---had 3-4 clicks down trim on elevator though--battery all the way forward to neutral cog !

Maybe characteristic of plane? Has good loop tracking--did split "s" perfect. I just have to have even more down to keep nose down to penetrate. I did try to move smaller battery back from very front 1/2 in or so--got worse ?

any one got anything else to try----Hobby shop advised me a customer put a 1/4 oz weight on tail ?

. It could use a little more power too. I'm used to my Quickie 500 sport--had OS 46 FSR ABC w/muffled tuned pipe on it---screamed. I converted it to electric w/32 eflite motor w/60amp esc--4s---not as fast as nitro though. Guys at the field always balked at it--"too noisy"--but was muffled tuned pipe---measured at 89 db--legal--used to tick them off.

I used to fly at a school--30-40 mins the "law" would show up !



thanks bob

Hi Bob :ws: the problem is that the main wing may have pos incidence causing it to climb under power, or you need more down thrust on the motor, to help to load the main wing, remember these planes are a power glider, and will climb under power, so you have to tweak them in to fly the way you want them to fly, your plane is fine for a beginner, but if you want it to fly straight and true like a pattern plane, its going to need some adjusting, check the wing and Stab incidence, 0-0 is what to look for, if thats ok, add more down thrust to the motor, and thats about all you can really do, weight on the tail end will just cause problems. hope that helps, Chellie

solentlife 12-27-2013 06:41 AM

Agree with Chellie ...

It takes a pattern machine to be neutral at power settings ... a typical model though will climb on full power ... descend at less than cruise.

The trick is to set up the model for what YOU prefer. Either shim the t/e of wing or alter motor thrust line. But note that it will only track straight and level at one speed.

I prefer to shim the wing, altering motor down thrust will alter the right thrust line also - so it's a play with washers affair that can get frustrating !

Altering tail is more difficult unless its a screw on job ... usually that's fixed and you have to live with it or cut and re-glue.

Nigel

CHELLIE 12-27-2013 06:49 AM

. It could use a little more power too. I'm used to my Quickie 500 sport--had OS 46 FSR ABC w/muffled tuned pipe on it---screamed. I converted it to electric w/32 eflite motor w/60amp esc--4s---not as fast as nitro though. Guys at the field always balked at it--"too noisy"--but was muffled tuned pipe---measured at 89 db--legal--used to tick them off.


Hi Bob :ws: your Quicky 500 needs a 5 cell lipo and a 9x9 prop, then you can play with the Big Boys again :D :D :D LOL,the E flite 32 motor is a low 770 kv motor, so you need more cells to wake it up, E Flite motors are under rated, so you can push them a lot.


JetPlaneFlyer 12-27-2013 09:37 AM

Quote:

Originally Posted by bigbob4877z (Post 935321)
--battery all the way forward to neutral cog !

No surprise that it's climbing under power if you had the battery all the way forward. Like i explained in my last post, you want to edge the CG back (i.e. move battery back) to reduce under power pitching up. This will of course mean more down trim, but that's ok.

JetPlaneFlyer 12-27-2013 09:41 AM

Quote:

Originally Posted by CHELLIE (Post 935340)
weight on the tail end will just cause problems.

Chellie, no it wont. Providing he's not already at the safe aft limit of the CG then moving it back some more (and trimming in some down elevator) will reduce climb under power. Shimming wings and tails wont work unless you also adjust CG to compensate.

Trust me, I'm not wrong on this.

fhhuber 12-27-2013 05:50 PM

If CG is too far forward, then you will have up-elevator trim in the aircraft.
At some speed that trim will be just right.
Slower and the nose will drop.
Faster and the nose will go up.

A definitive test for the CG being too far forward is to roll inverted.
The aircraft should require a small amount of down elevator to prevent pitching down.
More than 1/3 stick travel "push" for level inverted flight means the CG NEEDS to be moved back.
You can push the CG back safely to the point where no down elevator is required for inverted flight, but further is not recommended.
I have pushed the CG back past 40% MAC on some aircraft using this method to check where CG should be.

When making CG adjustments you can immediately move it anywhere within the kit/ARF/RTF model's listed range. The design will have been tested and safe to fly anywhere in that range.
Safe to fly does not necessarily mean it will fly well.. Just that it will be controllable and should be able to land at a reasonable speed.

If you are moving CG outside the instruction's recommended range do it SLOWLY at a maximum 1/10 of the CG range distance at a time. (1/8 inch or less if you don't have more than a single point given as recommended CG)

A very good example of an ARF/RTF with bad recommended CG is the Dynam Me-262. To achieve recommended CG (given as a point) it requires adding a large chunk of lead in the nose-gear retract well.
After much testing, I don't have that lead in my airplane and have pushed the battery back more than 3 inches from its most forward possible location, pushing the CG back more than 3 inches from the recommended location and it STILL needs to go back more.
I know why they recommend the far forward CG... the thrustline is so low that full power at low airspeed flips the plane. The correct fix is what they do with the full scale reproductions.... advance the throttle slowly until there is enough airspeed. (original full scale the engines required careful, slow throttle adjustment or they exploded)

*************

JPF is 100% correct

bigbob4877z 01-01-2014 01:28 AM

ok everyone--got it ! 2200 mah 1 /12 " foward from where I had it. Flying ok now--a little nose heavy---I guess I can slide it back a little more.

It could use a little more power. Anyone out there got any suggestions? It comes with a 235 watt motor. scorpion ?

thanks

CHELLIE 01-01-2014 06:44 AM

Quote:

Originally Posted by bigbob4877z (Post 935795)
ok everyone--got it ! 2200 mah 1 /12 " foward from where I had it. Flying ok now--a little nose heavy---I guess I can slide it back a little more.

It could use a little more power. Anyone out there got any suggestions? It comes with a 235 watt motor. scorpion ?

thanks

use this EasyStar power set up from Heads up RC, it will give you plenty of power, its a 2200KV motor, use a 6x4 or 6x3 prop, dont use a O Ring prop saver hub, use a Prop adapter, make sure the numbers on the prop face Forwards, your stock motor is a 200 watt, 28mm x 28mm 1100kv motor, Hope that helps, Chellie

BTW, tell Jeff at Heads Up Rc That Chellie sent you :D

http://www.headsuphobby.com/Firepowe...00kv-C-424.htm


Inrunner Brushless Motor - 2200kv

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  • Item #: C-424





The Firepower 450 Inrunner is a 3.2 oz, 2200KV, 290 watt direct drive inrunner brushless motor capable of producing 23 oz of thrust from a 3-cell Lipo battery. This motor is the same size as a speed 400 brushed motor, so it is a drop-in fit on many models. It weighs less than a speed 400 brushed motor, and produces more thrust.
The Firepower 450 Inrunner is a good choice for upgrading the Multiplex Easy Star, Multiplex Mini Mag, JR Hawk, and Wing Dragon to brushless power with very little effort. We suggest using an HURC 30A ESC, an EMP 6x3 prop, and an 11.1v 1500 30C to 11.1v 2200 50C Lipo battery for great performance with these models.
The Firepower 450 Inrunner comes with 3.5mm bullet connectors installed.
MOUNTING OPTIONS: The Firepower 450 Inrunner can be mounted behind a firewall, or on the front side of a firewall by using the 2800 series 'X' mount which is available in our store. A 3.17mm Prop Adapter can be purchased to mount a prop on the motor shaft. The GWS Plastic Outrunner Mount can be purchased to mount the Firepower 450 Inrunner on a 10mm stick.
Propeller Test Data for the Firepower 450 Inrunner
Battery Size Propeller Size Thrust (oz.) Amps Notes 3-Cell 11.1v EMP 6 x 3E 23 oz. 18 amps 3-Cell 11.1v EMP 6 x 4E 21 oz. 17 amps 3-Cell 11.1v APC 6 X 4 Speed 400 19 oz. 17 amps 3-Cell 11.1v EMP 5 X 5E 15 oz. 17 amps 4-Cell 14.8v EMP 4.5 x 4.5E 18 oz. 18 amps 290 watts 4-Cell 14.8v APC 4.5 x 4.1E 16 oz. 17 amps Please be aware that the battery used can make a tremendous amount of difference in the performance of brushless motors. The above data was obtained using batteries in good condition that were fully charged. Thrust and amp draw may be less with the use of batteries rated at lower amp output, and slightly more using batteries rated for higher amp output. Other factors, such as ESC timing and variations in actual motor KV can affect the performance of brushless motors as well. We recommend the use of a Watt Meter to test the current draw of your particular power system, especially if you plan to use a prop that pushes the motor near it's maximum amp rating.
Firepower 450 Inrunner Specifications:
Weight = 3.2 ounces (92 grams)
Diameter = 1.1 inch (28 mm)
Motor length = 1.37 inch (35 mm)
Shaft = 3.17mm x 0.5 inch (13 mm)
Voltage = 6 - 17 (2 - 4 cell Lipo batteries)
Max Current = 19 amps or 290 watts for 30 seconds
KV = 2200
Mounting holes are spaced 19mm and 16mm, and accept 3mm screws

JetPlaneFlyer 01-01-2014 08:35 AM

Quote:

Originally Posted by bigbob4877z (Post 935795)
ok everyone--got it ! 2200 mah 1 /12 " foward from where I had it.

I'm not sure you did 'get it'.. The advice (mine at least) was that the CG was probably already too far forward and by moving the battery further forward still you will have made it worse.

bigbob4877z 01-01-2014 03:17 PM

Wow Chellie - perfect ! I'll give them a call . I want to make sure it will bolt to the pod that's there. ?


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