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Extreme Flight Edge Build

Old 04-05-2017, 08:00 PM
  #1  
Vic Z
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Default Extreme Flight Edge Build

Like Derek I am building this plane. Quality and fit is awesome which is great since it is my first build and first balsa.
Used locktite on the control arms and put ca on the ends per Dereks experience. Got servos centered and all that.
Ready to put the cowl on but i used a laopared moror which is about 1/8" longer than suggested motor.
There is going to be about 3/8" between the spinner and the cowl which will look a little awkward.
Any tricks?
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Old 04-06-2017, 12:12 AM
  #2  
dereckbc
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There is some slop in the Cowl and it may be enough so that you can just extend the Cowl the 1/8 inch.

I made two mods one mod gave me COG issues to deal with that might bite you. I used the EF motor, but I used a Castle Creations Lite 50 ESC which is 14 grams heavier. To my disbelief it required me to use 3 of the Great Planes weights for a total of 21 grams on the rear LG. I drilled them out, and used longer wood screws that attach the LG to the fuselage. Otherwise it was real nose heavy. So make sure you check CG before maiden or else landing is not going to be fun.

FWIW use the Side Force Generators until you get real comfortable with the plane. Eliminates Tip Stalls, and if COG is right almost Zero Air Speed landings.
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Old 04-06-2017, 02:35 AM
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Only thing that crosses my mind is that some of the DuBro plastic spinners have about 1/8" between the shaft mounting surface and the outer rear diameter of the spinner. I prefer the EF aluminum backed spinners though. They are lighter and run truer in my experience.

Get that cowl extended as far as you can. I prefer to use card stock hinged on tape to set my hole locations. Using just tape can move around quite a bit while spanning some cowl gaps.

Another thing I like to do is mark the bottom of the wings at the center of the main spar. This makes it easier to reference when the wings are installed for final balancing.

I have a 176g motor on 1/2" Standoffs, 57g esc mounted right side of motor box and 20g servos. My 2650mAh 4s balances the plane with about 1 3/4" of the battery placed forward of the firewall, into the motor box. (yeah that heavy servo so far back creates a lot of tail weight).

This plane would make an ideal candidate for a carrier landing contest.

Last edited by birdDog; 04-07-2017 at 02:51 AM.
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Old 04-06-2017, 02:59 AM
  #4  
Vic Z
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Thank you.
Picked up the Dubro spinner. It does have the lip, but they are never true. Close enough I'm sure since it doesn't weigh anything.
Got it all together. Looks like my 4s 2200s will be a way into the motor box to cg if i use the spar. Might have a slight height problem when velcro is in.
Just need to install sfg's, secure battery, slap on the decals,and she is ready for maiden.
Thanks for the help guys.
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Old 04-06-2017, 04:47 AM
  #5  
dereckbc
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Originally Posted by Vic Z View Post
Thank you.
Picked up the Dubro spinner. It does have the lip, but they are never true. Close enough I'm sure since it doesn't weigh anything.
Got it all together. Looks like my 4s 2200s will be a way into the motor box to cg if i use the spar. Might have a slight height problem when velcro is in.
I just do not understand why my COG is so far off. I cannot even think about using 4S batteries. I am using 3S 2200 mah and they pretty much are as far back as they can go touching the Wing Tube. The ESC is only 14 grams heavier than the Airboss EF recommends. It took 21 grams of weight to get it to balance.
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Old 04-06-2017, 06:44 AM
  #6  
Vic Z
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That's strange that it would be so far off. The esc on yours is ony 1/4 oz heavier than recomended. I was thinking mine was almost tail heavy.
I havent measured yet. I just stuck my fingers under the wing tube when i was fitting the rx and such. That's probably close i imaging.
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Old 04-06-2017, 09:17 AM
  #7  
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The Edge is a bit restricted on motor choices if you want to have the cowl fitting correctly, you need a motor with a bolt on prop adapter, the collet type make the prop stand out too far.

CG depends on what motor you use. If you use a 150g motor your batteries will have to go well forward. A larger motor like dereckbg's 175g one and combined with batteries at the top end of the acceptable range (4S 2650) will make it nose heavy for sure.
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Old 04-06-2017, 05:53 PM
  #8  
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Originally Posted by JetPlaneFlyer View Post
CG depends on what motor you use. If you use a 150g motor your batteries will have to go well forward. A larger motor like dereckbg's 175g one and combined with batteries at the top end of the acceptable range (4S 2650) will make it nose heavy for sure.
Beg your pardon, but my motor is the Torque 2814T, weighs 143 grams, and using 3S 2200 mah batteries. It is nose heavy and took 21 grams in the tail to balance it.
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Old 04-06-2017, 08:02 PM
  #9  
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Originally Posted by dereckbc View Post
Beg your pardon, but my motor is the Torque 2814T, weighs 143 grams, and using 3S 2200 mah batteries. It is nose heavy and took 21 grams in the tail to balance it.
Sorry, on re-reading I see it was BirdDog and not yourself that mentioned the 175g motor and 4S 2650 batteries..

I can only think that your batteries are very heavy, or that you are trying to achieve a very rearward CG. The CG range in the manual is very much on the tail heavy side. This is because the mean chord line on the wings is swept forward which means that the Edge needs a more forward CG than the other planes in the EF range, but the manual is generic. It's been a while since I checked mine but 90mm from the LE rings a bell which is right at the front of the recommended range.

The inverted test will tell you if the CG is right. As I recall balanced in the middle of the suggested range mine climbed quite strongly when rolled inverted indicating a much too far rear CG. You see this in landing too, the plane tends to balloon when you slow for landing which makes landings tricky. I know a few people who got into all sorts of problems with their Edges simply due to using the CG as per manual, they tried resorting to all sorts of 'fudges' such as up-thrust on the motor to try so solve the problem that was in reality simply a case of CG too far back.

FWIW I use a 200g motor and still manage to get a perfectly trimmed CG even with a 4S 2600mAh battery, though the ESC and battery do have to be placed as far back as possible.

Last edited by JetPlaneFlyer; 04-06-2017 at 08:27 PM.
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Old 04-06-2017, 08:37 PM
  #10  
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Question is what C rating 3S are you using Derek ?

I can get a 3S 2200 heavier than a 4S 2600 just by going high on C rating ...

Nigel
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Old 04-07-2017, 01:34 AM
  #11  
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Originally Posted by solentlife View Post
Question is what C rating 3S are you using Derek ?

I can get a 3S 2200 heavier than a 4S 2600 just by going high on C rating ...

Nigel
Gen Ace 3S 2200 mah 25C. Yes I know a 30 or 40C 2200 will be heavier than 25C. That is why I am racking my brain.

I spoke with a user by the name of Doc Austin that shows up here and on RCG. He builds a lot of EF models and is stumped. He cannot imagine using a ESC 14 grams heavier would make it nose heavy especially since I used Digital HS 5077-MG servos which are a few grams heavier than the factory recommended servos.

Granted I am not an expert builder, but I did not stray far from the factory instructions. Only mods I made is using digital servos, upgraded ESC of 14 grams extra weight, and Dubro hinges. I have not looked at the specs of the factory recommended battery but the Gens Ace are suppose to be 184 grams.
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Old 04-07-2017, 01:38 AM
  #12  
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Originally Posted by JetPlaneFlyer View Post
I can only think that your batteries are very heavy, or that you are trying to achieve a very rearward CG. The CG range in the manual is very much on the tail heavy side.
Manual has it at 3.75 to 4.25 inches. I am using 4.00 inches using the Great Plains Balancer.

My only question is do I balance inverted or right side up? Does not seem to make much difference other than Inverted seems more sensitive. Even done it on my fingers.

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Old 04-07-2017, 02:46 AM
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1/8" (3.2mm) in FRONT of CENTER of wing spar. Slight amount of UP elevator STICK while inverted, very slight. Very very slight. Only a little. Tiny bit. And that is exactly where I intend to keep it.

51.8 ounces ready to fly with 284 gram 4s 2650mAh 40c stuffed 1.75" into motor box. (4x aluminum cased servos at 20g each)
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Old 04-07-2017, 07:18 AM
  #14  
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With mid wing models --- its always a matter to settle which way up to balance ...

I usually decide by picking up and trying each way by hand and see which is more stable to test. I know my EF Extra 300 is best inverted .... if I try right way up - its too sensitive and in fact can easily get it wrong.
Most models like this carry the battery above mid line of fuselage and of course we have rudder / fin etc above. This puts weight centre point above mid line of fuselage ... so inverted it is.

I have Hobby Kings version of that balancer .... its crap ! I mean the HK version !! The adjustable horizontals are so unstable .....

Nigel
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Old 04-08-2017, 06:11 PM
  #15  
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Originally Posted by dereckbc View Post
Manual has it at 3.75 to 4.25 inches. I am using 4.00 inches using the Great Plains Balancer.

My only question is do I balance inverted or right side up? Does not seem to make much difference other than Inverted seems more sensitive. Even done it on my fingers.
4" is too far back, move it the the front of the recommended range (3.5") or even slightly further forward. The manual is wrong on CG range, this has been pointed out many times by many users. FWIW Doc Austin also advises to use the very forward most CG position.

Don't get too excited about how you measure it, finger tips are good enough, fine adjustment should always be by flight testing anyway.

It's actually a testament to the docile nature of the Edge that it can be flown with the CG so far aft and still remain quite flyable, but you will see a very noticeable improvement if you move the CG forward.
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Old 04-08-2017, 06:23 PM
  #16  
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Originally Posted by birdDog View Post
1/8" (3.2mm) in FRONT of CENTER of wing spar. Slight amount of UP elevator STICK while inverted, very slight. Very very slight. Only a little. Tiny bit. And that is exactly where I intend to keep it.
If you really mean 'up' elevator (ie 'pulling the stick') then that would mean that the plane is trying to climb when inverted?.. If that's the case your CG is too far back, which is never a good place to be.
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Old 04-08-2017, 06:43 PM
  #17  
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PS.. I just checked my notes when I trimmed my Edge EXP back in 2012 and my memory turned out to be right. 90mm was where mine ended up after flight testing. This produced a neutral trim that would fly level either upright or inverted.

With a 3S battery this would usually mean having the battery stuffed well forward into the battery box. If you are using a heavier spinner that would also have an adverse effect on CG.
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Old 04-08-2017, 07:09 PM
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Originally Posted by JetPlaneFlyer View Post
If you really mean 'up' elevator (ie 'pulling the stick') then that would mean that the plane is trying to climb when inverted?.. If that's the case your CG is too far back, which is never a good place to be.

Which is exactly why I capitalized the words UP and STICK. I am well aware of the confusion surrounding elevator discussion.

All of these measurements, which can be skewed via center line vs. fuselage taper (yes, splitting hairs) and generally involve sighting to the leading edge, potentially adding parallax error, are the reason I like to measure using the wing tube as the datum. Looking back at my original measurement of 1/8" in front of center of wing spar, this places my CG at 86mm from leading edge, at fuselage. I would imagine a 90mm balance point (which would be balanced on the main spar) will give you a neutral CG, upright to inverted flight.

EXP series plane designs are extremely tuned. Well worth the money.

Last edited by birdDog; 04-08-2017 at 07:44 PM.
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Old 04-08-2017, 07:52 PM
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yeah, that's bang in line with my findings. 86mm should mean you need to ever so slightly 'push' the stick for inverted, 90mm is hands off level inverted.

100mm is crazy tail heavy and on most planes would probably not survive the first flight but the Edge masks a too far back CG remarkably well, you can get away with murder... But it still flies much better with a CG in the 85-90mm range.
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Old 04-09-2017, 02:30 AM
  #20  
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Originally Posted by JetPlaneFlyer View Post
4" is too far back, move it the the front of the recommended range (3.5") or even slightly further forward. The manual is wrong on CG range, this has been pointed out many times by many users..
I hope you are right. Can you link to a thread where that is stated?
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Old 04-09-2017, 03:09 AM
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3.38" Is my balance and 3.54" is Jetplaneflyers balance. 4" is way too far and this is where all your additional tail weight comes from. Ours balance on the main spar.

Trust me.
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Old 04-09-2017, 03:21 AM
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Found it!

That CG range is for the 60" Edge EXP.

http://extremeflightrc.com/assets/im...anual_rev1.pdf
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Old 04-09-2017, 05:34 AM
  #23  
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Originally Posted by birdDog View Post
Found it!

That CG range is for the 60" Edge EXP.

http://extremeflightrc.com/assets/im...anual_rev1.pdf
Thanks but mine is 48-inch. However I will try moving it up.

Last edited by dereckbc; 04-09-2017 at 06:06 AM.
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Old 04-09-2017, 12:00 PM
  #24  
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Yeah. It will work.

Last edited by birdDog; 04-09-2017 at 03:44 PM.
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Old 04-10-2017, 07:00 AM
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Originally Posted by dereckbc View Post
I hope you are right. Can you link to a thread where that is stated?
The CG is discussed many times in the very long 48" Edge EXP thread over on RCGroups, but the thread is thousands of posts long.

Just do the inverted CG test and it will instantly tell you if your CG is right or not.. To be fair the manual says that's how you should adjust the CG, so if you follow the manual you will end up ok.
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