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Old Jan 31, 2008, 05:10 PM
RocketRob is offline
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Lancer CG?


I have finishedmy 72" span Lancer from Bob Holman plans and have it set up for rc.
Does anyone have any suggestions for initial CG?
Thanks Rob
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Old Jan 31, 2008, 09:02 PM
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Poke the numbers into this CG calculator. Start with the static margin set to 10% and then do it again for 3 or 4% and that would be your preffered CG range.

http://www.geistware.com/rcmodeling/cg_super_calc.htm
Old Jan 31, 2008, 11:20 PM
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CG for Lancer


Quote:
Originally Posted by RocketRob
I have finishedmy 72" span Lancer from Bob Holman plans and have it set up for rc.
Does anyone have any suggestions for initial CG?
Thanks Rob
I agree with 10%. I've used Plane Geometry for Lancer CGs. It says 5.5 inches from the L.E. at the wing root for a lancer 72. I'm pretty sure we used this numer on a Mates model and it worked great.
Can we see some photos?
I'm a real fan of these models. Look and fly great.


Enjoy

Allan
Old Feb 01, 2008, 07:45 AM
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Thanks guys!

I'll get some photos, but we have had such rain for the month of January - I havn't been able to get her outside.

Currently it balances at the forward spar which is around 3" from leading edge.

It is powered by an inverted webra .28 diesel swinging a 10x6 prop
Last edited by RocketRob; Feb 01, 2008 at 07:55 AM.
Old Feb 02, 2008, 03:38 AM
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Beautiful Lancers Eut

Here is the one I got from Eut a couple of years ago. It has an MPX brushless motor. It is one of my prized possessions that I only fly on calm sunny days.
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Old Feb 02, 2008, 07:20 AM
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Hey Kasra,
That plane gets prettier every time I see it!
Kasra's Lancer was the inspiration for my Littlest Lancer which became the inspiration for my 72" Lancer.

Where is your CG relative to Main Wing Cord?
Old Feb 02, 2008, 01:33 PM
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Hey Kasra, did you recover the left stabilizer?
Old Feb 02, 2008, 09:28 PM
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3''aft leading edge works out to 33% MAC front wing - just a bit in front of the main spar

Flew very well

Plenty of power from the .28 Webra Diesel
10x6 apc 11,600 static

the calc program lists 4.04 lbs thrust and 65mph pitch speed
Old Feb 02, 2008, 09:52 PM
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Good looking Lancers. Rocket
Old Feb 02, 2008, 11:07 PM
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Thanks Man!
Old Feb 03, 2008, 06:12 AM
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Hi Rob, Nice looking Lancers. I like that hot red color I measured my CG at 3.75 inches tonight from the leading edge at the fuselage. The plane flies nose heavy and I will move the CG to 4" next. I don't know about 5.5 inches. That sounds a little too far.

Eut, I have not touched the airframe. Could you measure the CG on one of your Lancers please?

Thanks,

Kasra
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Old Feb 03, 2008, 04:45 PM
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Rearward CG


Quote:
Originally Posted by kasra
Hi Rob, Nice looking Lancers. I like that hot red color I measured my CG at 3.75 inches tonight from the leading edge at the fuselage. The plane flies nose heavy and I will move the CG to 4" next. I don't know about 5.5 inches. That sounds a little too far.

Eut, I have not touched the airframe. Could you measure the CG on one of your Lancers please?

Thanks,

Kasra
I'm pretty confident on the number at 5.5 inches. I've Used Plane Geometry a lot and have never come unstuck. Lancer has a generous tailplane and moment which lets the CG go back. The problem with forward CG is it makes for a one speed model. As soon as the pace goes on the nose comes up. It is too stable. I like to work the CG back to where the model only just pulls out of the dive when left alone. This way it si more sensitive to thermals too. 5.5 inches will still give positve recovery though as 10% margin is still nicely positive and is a good general seating before you start tuning.
Try working back to this and you will be rewarded with a more responsive and flaoty model when in lift. You may want to reduce elevator through as the sensitivity improves.

Allan

PS I would like to hear the veiws of a Master like Eut too!
Old Feb 05, 2008, 09:12 AM
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Kasra - Allan,
I think you guys both might be right.
I believe Allan is referring to the 72" span while Kasra is flying the 48-50" span?

Either way I have a rather large aft cg to explore!
Old Feb 17, 2008, 11:08 PM
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Some Aerials

4.04 lbs thrust in a 3lb, 1oz airframe and 65 mph pitch speed - Diesel

Not your grandaddys Lancer
Last edited by RocketRob; Feb 17, 2008 at 11:25 PM.


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