Extreme Flight 48 inch Laser EXP - Page 54 - RC Groups
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Jul 15, 2012, 04:27 PM
Facts, Logic, 3D
Tom K.'s Avatar
Quote:
Originally Posted by Batfire2000
My laser is nose heavy. 2200 4 cell 293 gr. Hacker A30-14L 143 gr. Hacker ESC 45 gr. MKS DS 6100 servos 9.5 gr. Cg at the middle of the wing tube. Battery was pretty far foward. Flew nose heavy. Ended up moving battery all the way back to the wing tube and still flies nose heavy. Just does not make sence to me. Has anyone had to add weight to the tail ?? Thanks
What does it do when you flip it inverted at 3/4 throttle?

--Tom K.
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Jul 15, 2012, 04:50 PM
Registered User
Continues to drop, fast
Jul 15, 2012, 04:51 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Quote:
Originally Posted by Batfire2000
My laser is nose heavy. 2200 4 cell 293 gr. Hacker A30-14L 143 gr. Hacker ESC 45 gr. MKS DS 6100 servos 9.5 gr. Cg at the middle of the wing tube. Battery was pretty far foward. Flew nose heavy. Ended up moving battery all the way back to the wing tube and still flies nose heavy. Just does not make sence to me. Has anyone had to add weight to the tail ?? Thanks
IMHO the Laser does tend slightly to nose heaviness. It needs to balance at the former behind the wing tube for neutral handling but if you use a heavy battery that's hard to achieve.

I think your problem is very light servos and a rather heavy battery. I used Savox servos (SH-0255 and 0257) which add about 13g to the tail compared to yours and my battery (Gens Ace 4s 2200mAh) is only 250g. With this kit I need the battery to be almost at the wing tube, so I can see how you will be nose heavy.

I certainly recommend beefier servos anyway, you really need them, especially on the elevator. The other easy change is go for a wood prop (if you haven't already), that can take 10-15g off the nose. lighter batteries would be good too, I'd recommend the Gens Ace 30c.
Jul 15, 2012, 05:07 PM
Facts, Logic, 3D
Tom K.'s Avatar
Quote:
Originally Posted by Batfire2000
Continues to drop, fast
Yikes! That sounds extremely odd. Normally these EF planes balance around the same area or at least within reason.

--Tom K.
Jul 15, 2012, 05:32 PM
Registered User
What seems so strange to me is when you CG the plane on the ground it seems tail heavy. So I move the battery foward and it balances. Fly it, nose heavy, move the battery back several inches, nose heavy. ???
Jul 15, 2012, 05:34 PM
Volts>amps
stgdz's Avatar
Quote:
Originally Posted by Batfire2000
What seems so strange to me is when you CG the plane on the ground it seems tail heavy. So I move the battery foward and it balances. Fly it, nose heavy, move the battery back several inches, nose heavy. ???
So what does it do when you put it in a dive 3-400 ft up?
Jul 15, 2012, 05:42 PM
Facts, Logic, 3D
Tom K.'s Avatar
Quote:
Originally Posted by Batfire2000
What seems so strange to me is when you CG the plane on the ground it seems tail heavy. So I move the battery foward and it balances. Fly it, nose heavy, move the battery back several inches, nose heavy. ???
Maybe something's screwy. I'll probably get my head bit off for saying this, but have you checked the incidence and/or thrustline? It's a possibility. To check for thrustline (easiest), trim for upright level flight at 3/4-full throttle. Fly across the field upright at 3/4-full throttle into the wind, and chop the throttle and take your fingers off the sticks. If the plane climbs, too much downthrust (Motor pulls plane down, counter with up trim. Motor no longer pulling plane down, up trim only factor), if it dives, too much upthrust (visa versa), if it keeps going straight, then the thrustline is fine. The other thing to do would be to level the fuse up on a workbench and use an incidence meter to check the incidence of the wings and stab. Sometimes people mistake a mechanical issue like this for CG, so it's understandable. I had a brand X have way too much downthrust AND incidence issues, and the dang thing flew around like it had an elephant riding in the trunk!

Thrustline is easy to fix... just shim the motor up or down with washers or other shims. Incidence is a bit tougher to mess with, so hopefully it's either thrustline or CG.

Good luck! If you have any in-depth questions or comments feel free to PM me.

--Tom K.
Jul 15, 2012, 05:51 PM
It's gone...
_OZ_'s Avatar
All that matters is how it flies. The published CG is just a starting point to tune from. It takes quite a few flights to get things right.
I don't have the Laser but I do have the 48" Extra 300 and the two wont be dramatically different. I added 7 grams to the tail of mine Extra and that allowed me to move the pack forward and off the wingtube.
I followed the procedures outlined in my blog link below.
It took some time, but I feel the efforts were worth and I learned a lot about how different things affect how the plane flies.

Tom is an excellent pilot form what I have seen and his advice is usually just as excellent, but I would not go changing thrust lines and incidences yet. The Goldsmith guide will address those issues after you have set your CG. Give it a shot, I think you will like the results.
Jul 15, 2012, 06:00 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Quote:
Originally Posted by Batfire2000
What seems so strange to me is when you CG the plane on the ground it seems tail heavy. So I move the battery foward and it balances. Fly it, nose heavy, move the battery back several inches, nose heavy. ???
Did you read my previous post? I have a Laser, it needs to balance at the former behind the wing joiner tube for neutral trim. if it balances much further forward than that then it will be nose heavy in flight..

So where does it balance?

Steve

PS.. i agree , whatever you do dont even think about adjusting thrust lines or incidence angle.. this simply sounds like you are balanced nose heavy, the CG location advised in the manual is a bit far forward, so don't pay much attention to it.
Jul 15, 2012, 06:44 PM
It's gone...
_OZ_'s Avatar
Quote:
Originally Posted by JetPlaneFlyer
...it needs to balance at the former behind the wing joiner tube for neutral trim. if it balances much further forward than that then it will be nose heavy in flight..
That is the same place my Extra balances too.
Jul 31, 2012, 10:43 AM
C-Main Champ
djmoose's Avatar
Hey guys, just wanted to let you know that thanks to Chris Hinson, ATTF is giving away a Laser EXP as one of our grand prizes for August.

http://allthingsthatfly.com/prize.php

Thanks Chris!
moose
Jul 31, 2012, 12:12 PM
Some.. call him Tim...
Ducati Mechanic's Avatar
Nice! I think I need a car decal..
Jul 31, 2012, 05:03 PM
inverted-i-fly
3drcparts's Avatar
Dam, ripped my landing gear block out today in a harder than expected harrier landing, landing gear is fine, pretty shocked that the block broke before the gear
Jul 31, 2012, 05:14 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Quote:
Originally Posted by Inverted-I-Fly
Dam, ripped my landing gear block out today in a harder than expected harrier landing, landing gear is fine, pretty shocked that the block broke before the gear
That's not so good.. did you CA all the joints around the gear plate like the manual says? Lets hope this isn't a sign of a inherent weakness, do you have any photos to show where it failed?

FWIW I bust the l/g leg on my Laser second time out, it didn't do anything to the mounting plate.
Jul 31, 2012, 05:50 PM
It's gone...
_OZ_'s Avatar
Quote:
Originally Posted by djmoose
Hey guys, just wanted to let you know that thanks to Chris Hinson, ATTF is giving away a Laser EXP as one of our grand prizes for August.

http://allthingsthatfly.com/prize.php

Thanks Chris!
moose
Entered! Thanks Moose and Chris!


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