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RE: Sig Kougar Build - 3/18/2010 3:36 PM   
racingjeff1



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Status: offline 		On 6S @ 1700W that should really move, unless that plane weighs 10lbs+. Sounds as if you may not have the correct electric setup. There are not too many planes that can catch my Kougar and I am running a 14.8v setup at just under 1000W.

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RE: Sig Kougar Build - 3/18/2010 6:37 PM   
_Tommy D



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quote:

ORIGINAL: racingjeff1

On 6S @ 1700W that should really move, unless that plane weighs 10lbs+. Sounds as if you may not have the correct electric setup. There are not too many planes that can catch my Kougar and I am running a 14.8v setup at just under 1000W.


Hi Jeff

I’m always open to suggestions so here is my setup.

Scorpion 4020 12. On 6S it turns a 12x12 @ just about 10,000 RPM. It’s costing me 72A on a 6S LiPo. Under load the battery sags to about 3.75 VPC.

The Watt reading is just over 1700. I don’t put much faith in total watts as it’s RPM that moves a plane. However with that said with so little heat generated I’m definitely not adding watts via heat/waste.

Model has a 61” WS and resembles a Kaos. AUW is in the 6.5lb range.

Flat and level it’s about 100 MPH. Better in a dive so perhaps “fast” is relative to some degree.

Tommy D


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RE: Sig Kougar Build - 3/18/2010 7:07 PM   
racingjeff1



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Status: offline 		Hi Tommy,

I would have to say you have the wrong setup. 6.5lb plane should run 5S pack preferable 5000maH. Your motor rpm/kv is too slow, and your prop is not matched to a motor that is requiring a large prop, by large I mean something like a 15x8 or 15x10. I have seen a number of websites and mfg sites that try to equate a glow or gas engine to a electric motor that are way to simplistic. Your own comment is curious about the "rpm moving the plane" that would be true in a glow where the engine wants to run at a high rpm naturally where it makes usable rpm power, then needs to be constricted by a prop to bring it down to a useful rpm for actual torque, basically a fight going on there. Whereas electric motors make theoretical torque naturally at 0 rpm, but obviously that is not useful but we can operate them at low rpms to make the torque we need. So off the top of my head you need a motor in the 50-60-650 to 750 rpm/kv range on an 15x8 or 10 prop on a 5S Lipo. Those are numbers from some testing and in practice, I use motocalc as well as a neat bench test rig to get real data. However I did not work an exact details workout for your specific airplane, I am just giving you an idea.

If you did not know about it already try http://www.motocalc.com for some fun computer sims. I did find some pitfalls when bench testing real systems.

Jeff

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RE: Sig Kougar Build - 3/18/2010 9:18 PM   
_Tommy D



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Status: offline 		Jeff

The only way I'm going to be able to swing a 15" screw is....

I convert the model to a tail dragger I think traditional trikes look beyond dumb as tail draggers. Ill give ya some slack if you retract them up though!

Bend new legs that resemble a Giraffe in length!

Sorry son it's 12"s or SMALLER on this one. The airframe selected the prop diameter for me, so all I can do is operate a low KV motor on high volts and try to emulate a 2S setup.



Thanks

Tommy D

FYI all you ever wanted to know about Props can be found here. I don't put much merit on test rigs these days. When I started to use in flight data capture devices it indicated that static test rigs were usually good enough for... well just that "good enough" or ballpark.



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RE: Sig Kougar Build - 3/18/2010 10:06 PM   
racingjeff1



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Status: offline 		you can try a HIGHER rpm/kv motor then to turn that 12x12 in the proper range.

Well I have been running electrics since the days of Nicads, have converted several models of my own and friends aircraft of all sizes and I can tell you by initial motocalc tests that were then proven on my bench test dyno are right on.

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RE: Sig Kougar Build - 3/19/2010 1:02 AM   
_Tommy D



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quote:

ORIGINAL: racingjeff1

you can try a HIGHER rpm/kv motor then to turn that 12x12 in the proper range.



Jeff

I'm already in the 70A range. I want to fly not weld ! =) That is if your suggesting an even higher KV motor on 6S.

At 70+A the VPC is dropping to 3.7. Can't go any higher. Heck the CC 80 is right at the limit if you know what I mean.

No this setup would work nice is say a smaller airframe like the Kougar, I'm afraid my bird is too big/draggy.

Say, what setup are you flying in your Kougar? From looking at the huge fuel tank area/short nose I was thinking something in the 8S range if I ever converted one.

Take Care

Tommy D


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RE: Sig Kougar Build - 3/19/2010 4:58 AM   
_Tommy D



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Status: offline 		Well I ran the old Max H 40 tonight. Had to tighten the head a bit but otherwise ran pretty darn good. Has a nice low idle and revs up pretty nice.

Think Ill fly it on this and keep the OS 46AX on the shelf for now.

Tommy D

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RE: Sig Kougar Build - 4/11/2010 12:28 AM   
_Tommy D



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Status: offline 		Score 1 more Kougar at Toledo!



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RE: Sig Kougar Build - 4/11/2010 1:02 AM   
claude roland


 

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RE: Sig Kougar Build - 4/12/2010 5:26 PM   
BillS


 

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Status: offline 		For what it is worth:
With standard gear a 11-diameter prop clips the grass on take off on landing. An 11” X 6 prop idols better on an OS 50 but I prefer to use a 10” X 8 prop even though landings are too fast.

Don’t see how props larger than 11 “ diameter could be satisfactory.

Bill


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RE: Sig Kougar Build - 4/14/2010 8:20 PM   
BillS


 

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Status: offline 		Someday when all my Kougars are beyond repair an ARF substitute will be necessary. Has anyone found an ARF that flies like the Kougar?

Bill

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RE: Sig Kougar Build - 4/14/2010 11:45 PM   
JWQ500RC



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Status: offline 		Nothing flies like a Kougar!!

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RE: Sig Kougar Build - 4/18/2010 9:45 PM   
_Tommy D



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Status: offline 		Guys

Where exactly is the balance point for the Kougar?

I just refit mine with a OS46AX and with no fuel in the model its very nose heavy as balanced by Sigs web site instructions. They suggested near 8"s inverted from the TRAILING edge of the wing.

Thoughts?

Thanks

Tommy D

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RE: Sig Kougar Build - 4/19/2010 7:37 PM   
BillS


 

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Status: offline 		All my manuals state "1/2 back from the leading edge at the wing tip.

Bet it will not fly long at 8" from the trailing edge which looks to be about 1" too far back.

Bill

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RE: Sig Kougar Build - 4/19/2010 8:52 PM   
_Tommy D



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Status: offline 		Thanks Bill

I placed pins at about 1/2 and 3/4" back from the LE at each ting tip. Then I connected a string, and marked the wing nearest the fuse.

I'm slightly rearward of the 3/4" CG however I'm thinking with Fuel the model will be forward of the CG.

Sig must be measuring without the Ailerons, as there about 1".

Tommy D

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RE: Sig Kougar Build - 4/20/2010 6:19 PM   
BillS


 

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Status: offline 		I also use the string method but mark the top of the canopy since I balance in a cradle.

The Kougar flies well with a forward CG and slight up reflex in the ailerons and first flights are much safer. A little rear CG amplifies any bad traits. Stall and snap can be pronounded as the CG is moved back. Stall speed is high and I like to find out what speed stalls occur before moving the CG back.

Good luck with the initial flights.

Bill

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RE: Sig Kougar Build - 4/25/2010 1:11 AM   
_Tommy D



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Status: offline 		Kougar maiden went off ok. Just a few minor glitches.....

Really climbs like a home sick angel when given the guns. Looks like there is almost no down-thrust on the model. Do you guys know what it calls for? I was going to add a few degrees to try and help out the climb. Also model needs a ton of elevator to hold inverted. Figure changing the thrust line would not hurt here either.

Otherwise it's a fine model.

Tommy

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RE: Sig Kougar Build - 4/25/2010 9:37 PM   
_Tommy D



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Status: offline 		... added a couple of degrees of down thrust, will see what happens next time.

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RE: Sig Kougar Build - 5/1/2010 6:21 AM   
_Tommy D



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Status: offline 		2 degrees of downthrust helped out a lot. I only made 2 flights today <15+ MPH winds> and should know more Saturday with lighter winds.

Man, this is one nice landing model!

Tommy D

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RE: Sig Kougar Build - 7/4/2010 7:08 AM   
yukonpete



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Status: offline 		I completed my Kougar today. The build lasted 3 weeks and I will try an maiden her next week.


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RE: Sig Kougar Build - 7/4/2010 8:54 AM   
claude roland


 

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RE: Sig Kougar Build - 7/4/2010 10:30 AM   
YUKONFLYR



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quote:

ORIGINAL: yukonpete

I completed my Kougar today. The build lasted 3 weeks and I will try an maiden her next week.



Nice Job Pete on the Kougar!

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RE: Sig Kougar Build - 7/4/2010 7:04 PM   
catracer343



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Status: offline 		I just finished up my Kougar a few days ago...#2 for me! -Can't wait to get it up in the air! I made a few small mods to this one...let's hope the ailerons don't buzz of it on a high speed dive!

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RE: Sig Kougar Build - 7/4/2010 8:01 PM   
claude roland


 

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Status: offline 		The KOUGAR is the most beautiful airplane rc world in my opinion

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RE: Sig Kougar Build - 7/4/2010 8:06 PM   
yukonpete



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Status: offline 		I'm yet to fly one! I will let you know nexrt week what I think


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