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Old Nov 17, 2012, 02:39 PM
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eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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I think a lighter prop will just put less strain on the motor when accelerating. Not a lot in it though.

What size and pitch of prop are you using?
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Old Nov 18, 2012, 09:01 AM
Cut it twice, still too short
dglo's Avatar
Bay City, MI
Joined Oct 2007
647 Posts
The prop is a 16-10. Never used a Zoar prop before, it really is a thing of beauty. I should sand the finish off and paint it gray to look more scale, but don't know if I can bring myself to do that.
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Old Nov 18, 2012, 09:13 AM
Right Rudder
PittSpecial's Avatar
USA, FL, Orlando
Joined Nov 2010
9,675 Posts
Quote:
Originally Posted by dglo View Post
Quick update. Spent several hours with the dremel working on the wings and fuse, removed a grand total of one ounce. Also bought a Zoar wood E prop that weighs 1/2 ounce less than the APC. Don't know if the weight of the prop is a factor while in flight or not, but at least it will look a little better sitting on the scale. Also got some covering done, the polyspan is on both wings, when I get the fuse done I'll post some pics.

Doug
Doug,

It certainly does makes a difference. The less "Mass" up front on an Electric Motor the better assuming a good strong made propeller.

I believe you meant to say XOAR propeller.

Carlos
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Old Nov 18, 2012, 10:59 AM
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eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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Right - definitely don't give up on 3S then - you have plenty of pitch.
Watch out for the swing on take-off though. Best open the throttle slowly - looks more scale anyway.
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Old Nov 18, 2012, 11:02 AM
The Hun in the Sun
vonJaerschky's Avatar
Canada, BC, Comox
Joined Nov 2003
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It's a big rudder Robin, and mine shows no tendency at all to yaw drastically. I'm using an APC 16X10. A little bit of right rudder keeps her straight, even if jamming the throttle open (Which I agree just looks terrible!). It is without doubt the best flying model I've had in 30 years of this madness. In fact, I partially blame it for the crash of my Bf-109. I flew the Jungmeister a lot, and I got to the point that I forgot to remember that not everything flies so forgivingly!
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Old Nov 18, 2012, 11:27 AM
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E-Challenged's Avatar
United States, CA, Garden Grove
Joined Oct 2000
12,197 Posts
Quote:
Originally Posted by dglo View Post
Question: The more I research the subject, the more confused I get. Should I install a seperate switching bec? I'll be using a scorpion commander 70 amp esc with a 5v 4amp linear bec on 3s lipo. From what I can figure out this is kind of borderline as to wether to use a seperate bec or not. Any help? I'm using 2 Hitec HS635HB servos on elev and rud and 2 HS225BB servos on the ailerons.

Thanks,
Doug
Go to Dimension Engineering's website, read FAQ's on when you need to use a switch mode BEC and what amp rating you need for 3S and four full size servos. ( I use their Park BEC's rated at 1.5 amps for 3S lipos, 2.4Ghz receiver and four or more small servos. They have BEC's with higher amp rating for larger stuff/better safety margin to prevent brownout crashes. Alternative is to use separate flight battery pack to power receiver and servos same as in IC powered model and disable the Scorpion linear built-in BEC. Don't risk a crash with linear BEC.
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Old Nov 18, 2012, 02:56 PM
Cut it twice, still too short
dglo's Avatar
Bay City, MI
Joined Oct 2007
647 Posts
Carlos, Yes, I did mean XOAR.

Frank, Love hearing you talk about how well she flies, gets me more excited. Wants me to have her ready for maiden before the snow flies, but it'll probably be Spring.

Robin, thanks for the advice

E-Challenged, I've already been convinced by others, read the FAQ's, and installed a Sportbec, which is one step up from the parkbec, another problem solved by RCG before it caused a crash.
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Old Nov 18, 2012, 03:30 PM
Registered User
United States, TN, Blountville
Joined Oct 2002
3,586 Posts
Quote:
Originally Posted by dglo
Question: The more I research the subject, the more confused I get. Should I install a seperate switching bec? I'll be using a scorpion commander 70 amp esc with a 5v 4amp linear bec on 3s lipo. From what I can figure out this is kind of borderline as to wether to use a seperate bec or not. Any help? I'm using 2 Hitec HS635HB servos on elev and rud and 2 HS225BB servos on the ailerons.

Thanks,
Doug


Quote:
Originally Posted by E-Challenged View Post
Go to Dimension Engineering's website, read FAQ's on when you need to use a switch mode BEC and what amp rating you need for 3S and four full size servos. ( I use their Park BEC's rated at 1.5 amps for 3S lipos, 2.4Ghz receiver and four or more small servos. They have BEC's with higher amp rating for larger stuff/better safety margin to prevent brownout crashes. Alternative is to use separate flight battery pack to power receiver and servos same as in IC powered model and disable the Scorpion linear built-in BEC. Don't risk a crash with linear BEC.

225BB servos according to Servo City...
Control System: +Pulse Width Control 1500usec Neutral
Required Pulse: 3-5 Volt Peak to Peak Square Wave
Operating Voltage: 4.8-6.0 Volts
Operating Temperature Range: -20 to +60 Degree C
Operating Speed (4.8V): 0.14sec/60 at no load
Operating Speed (6.0V): 0.11sec/60 at no load
Stall Torque (4.8V): 54.15 oz/in. (3.9kg.cm)
Stall Torque (6.0V): 66.65 oz/in. (4.8kg.cm)
Operating Angle: 45 Deg. one side pulse traveling 400usec
360 Modifiable: No
Direction: Clockwise/Pulse Traveling 1500 to 1900usec
Current Drain (4.8V): 8mA/idle and 300mA no load operating
Current Drain (6.0V): 8.8mA/idle and 340mA no load operating
Dead Band Width: 8usec
Motor Type: 3 Pole Ferrite
Potentiometer Drive: Indirect Drive
Bearing Type: 1 Ball Bearing and 1 Oilite Bushing
Gear Type: Nylon
Connector Wire Length: 11.81" (300mm)
Dimensions: 1.27" x 0.66"x 1.22" (32.4 x 16.8 x 31mm)
Weight: 0.95oz (27g)

Granted under load, those current numbers are worthless other than idle and could be much higher.

HS635HB servos according to ServoCity:
Control System: +Pulse Width Control 1500usec Neutral
Required Pulse: 3-5 Volt Peak to Peak Square Wave
Operating Voltage: 4.8-6.0 Volts
Operating Temperature Range: -20 to +60 Degree C
Operating Speed (4.8V): 0.18sec/60 at no load
Operating Speed (6.0V): 0.15sec/60 at no load
Stall Torque (4.8V): 69 oz/in. (5.5kg.cm)
Stall Torque (6.0V): 83 oz/in. (6kg.cm)
Operating Angle: 45 Deg. one side pulse traveling 400usec
360 Modifiable: Yes
Direction: Clockwise/Pulse Traveling 1500 to 1900usec
Current Drain (4.8V): 5.3mA/idle and 400mA no load operating
Current Drain (6.0V): 6.6mA/idle and 500mA no load operating
Dead Band Width: 4usec
Motor Type: 3-Pole Ferrite
Potentiometer Drive: Indirect Drive
Bearing Type: Dual Ball Bearing
Gear Type: Karbonite Gears
Connector Wire Length: 11.81" (300mm)
Dimensions: 1.6" x 0.8"x 1.5" (40 x 20 x 39mm)
Weight: 1.83oz. (52.1g)

So, at no load, you are looking at minimum of an amp used by elevator and rudder without load but operating. The ailerons working will draw over 0.6A. Presuming the power needs of the receiver are 500 mA, then you are looking at conservative numbers of 1.0 + 0.6 + 0.5 or 2.1A What are your Rx specs?
Putting an amp meter on the ground on the positive from the Scorpion ESC's RX connection will give you a close to no load reading. Granted you have load from linkages, only when the servo has nothing but the horn/wheel will it see "no-load".
You would need something like an Eagle Tree system to get true flight loads on the servos to give accurate estimates of typical loads being recorded. With the design of the controls to be very light throughout the range of motion, if the model has similar setup for its flight controls the servo loads would stand to reason be less and more consistent throughout the range.
A servo at 60 degrees and holding may draw far less than between 0 and 60 and getting there...
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Old Nov 19, 2012, 03:08 AM
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eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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Of course you could attack the 'problem' from the other direction and instal some non-scale (perish the thought!) servo assist tabs to take most of the workload off the servos... if you're worried enough of course!

Makes more sense with a larger multi-engined type that is supposed to have trim tabs though...
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Old Nov 26, 2012, 07:51 PM
Cut it twice, still too short
dglo's Avatar
Bay City, MI
Joined Oct 2007
647 Posts
Covering is done!

Finished all the covering. When I started painting the white, I realized everything would need a second coat of polycrylic, so now that's done and I can get on to painting but I'm waiting on some graphic tape for making panel lines. Meanwhile I got the inst. panel done, the ailerons painted and some other little stuff. Still have to make up some plastic access panels and other little doo-dads to glue onto the fuse before painting.
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Old Nov 27, 2012, 05:15 AM
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eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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WOW! Love the instrument panel!

Where did THAT come from??!
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Old Nov 27, 2012, 05:53 AM
What's 3D?
trumps's Avatar
Australia, WA, Ellenbrook
Joined Feb 2008
3,316 Posts
Excellent work bud, looks good.

Craig
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Old Nov 27, 2012, 06:30 AM
Cut it twice, still too short
dglo's Avatar
Bay City, MI
Joined Oct 2007
647 Posts
I bought the gauges off the internet, don't remember where but they are 1/5 scale german WW2 era, 20 bucks I think. The panel is just foam fanfold sanded to the right thickness painted with testors enamel. I made the mag switch from a piece of balsa and a push pin.
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Old Nov 28, 2012, 09:08 AM
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eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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Well it certainly looks good Doug.

If you remember where could you post a link to the site so I could have a look and see if they have British types of the era just before the war please?
I have a DH Fox Moth to the same scale at about the same stage as yours.

The only trouble would be that my external finish is not likely to do justice to instruments like that!
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Old Nov 28, 2012, 10:54 AM
The Hun in the Sun
vonJaerschky's Avatar
Canada, BC, Comox
Joined Nov 2003
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Quote:
Originally Posted by dglo View Post
I bought the gauges off the internet, don't remember where.
I would guess that they are from aerocockpit in the Czech republic. I got the instruments there for my Jungmeister, and they also made the panel kit for my Bf-109.
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Last edited by vonJaerschky; Nov 28, 2012 at 11:11 AM.
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