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Apr 21, 2017, 07:15 PM
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Thunder Chicken's Avatar
I received the 800mm Rainbow V2 a while back. I ran a 2204-2300kv quad motor, 6x4 prop, 25a esc, 3s 850 battery and MG90 servos. I moved the servos out the wing a bit to line up better with the hinge line. It weighed in at 235grams.
The control surfaces were very stiff, so i cut some slots in the hinge. On the second flight, i lost elevator control in a fast dive. It had been fine at slower speeds. Maybe the MG90's were not up to the task but I find it hard to believe! At any rate, some hot glue and hinge tape is now required. The wing tried to peel itself apart from the center section forward towards the spar cutouts. This is my first EPP foam plane, way more durable than foam board, balsa...forget it!
Maybe some laminating film would stiffen it up and help it to hold together, but id really like to figure out why I had no control response. This is my first wing, but I cant see it having trait like that. Im guessing just a combo of stiff hinge line, fast flight and maybe the wing flexing enough to bind the elevons.
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Apr 21, 2017, 07:23 PM
BMAT prior life.. USAF Retired
PHerder's Avatar
Grantham Kid posted how he loosens up the hinge foam in a video at the bottom of post #1.

I tried it with good results.
Apr 21, 2017, 09:03 PM
Up! Up! And Away!
GottaZoom's Avatar
Quote:
Originally Posted by Thunder Chicken
Im guessing just a combo of stiff hinge line, fast flight and maybe the wing flexing enough to bind the elevons.
Hoping to throw mine up for a maiden next week. Finished it up today but I should have listened and changed out the elevon horns from the start .... now I get to redo them since the stock horn folded there is no down elevator on one side.

Oh, what glue did you use?

Quote:
Originally Posted by PHerder
Grantham Kid posted how he loosens up the hinge foam in a video at the bottom of post #1.
Did that also. 5g servos are handling them but even still they are still a still stiff versus my Delta Ray foam hinges.
Apr 22, 2017, 09:23 AM
flyin' fool
goldguy's Avatar
Balancing a wing................

Start off with balancing from tip to tip. Then check the factory recommendation here .................... http://fwcg.3dzone.dk/. Start off with 19/20 percent.

Hand toss without the prop and look for the sweet spot, which is the least amount of reflex using CG adjustments of give you a nice long flat glide without any TX input.

On the power maiden, don't slam open the throttle on launch, you'll only make bad things worse.

Patience if the key word.
Apr 22, 2017, 09:28 AM
flyin' fool
goldguy's Avatar
Smooth easy flexing hinges are best done with an iron. This actually strengthens the hinge, as scrapping can cause damage. Test on a scrap to find the correct temp. Run the iron once over the completely flexed hinge, then flex back and forth until cooled.
Apr 22, 2017, 01:07 PM
Up! Up! And Away!
GottaZoom's Avatar
Quote:
Originally Posted by goldguy
...Then check the factory recommendation here .................... http://fwcg.3dzone.dk/. Start off with 19/20 percent.
Thanks. My quick (imprecise) estimates show 110mm is very close to 20% and the range is fairly small. Will start with the heavier battery.
Apr 22, 2017, 03:43 PM
flyin' fool
goldguy's Avatar
On small wings, even 1/8" makes a big difference.
Apr 24, 2017, 11:58 AM
Registered User

Updated FPV Pod


Updated FPV pod with larger battery area. Will fit a Runcam HD and battery (max battery dimensions 62mm x 19mm)
Apr 25, 2017, 05:41 PM
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Thunder Chicken's Avatar
Thanks for the CG link above!
Im thinking this too hard through though......
at 110mm, im tail heavy. almost a 1/4" farther back balances it, making it "tail heavy'. However, when i hand toss it, it nose dives. Flying it, it would not pull out of a dive.
at 1/2 throttle it handles fine, WOT it would climb a bit but was basically in trim close enough.
Apr 25, 2017, 06:07 PM
Chasin' that Neon Rainbow
Grantham Kid's Avatar
Thread OP
Quote:
Originally Posted by Thunder Chicken
Thanks for the CG link above!
Im thinking this too hard through though......
at 110mm, im tail heavy. almost a 1/4" farther back balances it, making it "tail heavy'. However, when i hand toss it, it nose dives. Flying it, it would not pull out of a dive.
at 1/2 throttle it handles fine, WOT it would climb a bit but was basically in trim close enough.
How much reflex have you got? If it dives from a hand toss, you don't have enough reflex. Full stop.

Can you take some photos showing how you have set it up?

I really think it is a build issue as these are very easy to set up.

GK
Apr 27, 2017, 07:36 AM
Registered User
Thunder Chicken's Avatar
I'll get a pic next time im out flying, but that'll be a few weeks now, just got a surprise storm of 10" of snow......
I've completely rebuilt it from its last crash, i'll make sure there's some reflex, i had a slight amount before, but likely not enough? It launched fine with 1/2 throttle and was in trim flying around at 1/2 throttle or so, but would not pull out of a WOT loop =)
Should the motor have any down thrust? I also did not use the plywood motor mount, i made a wedge from EPP glued to the top of wing like the crash test hobby scythe.
Apr 27, 2017, 05:40 PM
Chasin' that Neon Rainbow
Grantham Kid's Avatar
Thread OP
Minimum of 6 -7 mm reflex for a start. You only need enough that the plane will glide nicely without power.
If the plane climbs under power then you need motor downthrust. (motor lower at the back)
Apr 28, 2017, 07:04 PM
Chasin' that Neon Rainbow
Grantham Kid's Avatar
Thread OP
Snow is a good time to test it. Soft landing.... LOL
Just make sure the ESC doesn't get wet.
May 04, 2017, 05:05 PM
Registered User
Thunder Chicken's Avatar
Thanks to the advice, the wing flew fine today! I'm very happy with it infact, for $20cdn!!!
I may laminate it (or the next one more likely).
I have a 2204-2300kv motor, 850, 3s battery on it and it goes like stink. Now that i have it flyign nice, i was able to get some expo dialed in and make it a smooth flyer. I need a bit of down thrust, or a mix on throttle/elevator, as it does climb under power. (mix will be easier!)
We have 2 of these in the club now, time for some combat!
(pic of the reflex Grantham, I had to add a fair bit from what I had)
May 04, 2017, 07:05 PM
Chasin' that Neon Rainbow
Grantham Kid's Avatar
Thread OP
That reflex looks very similar to mine. Great that it has overcome your problem.
I personally prefer to pack out the top of the motor with little washers rather than mixing but each to their own.
Have fun.


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