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Old Apr 08, 2012, 09:33 AM
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Hampton, VA
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Swimmer,

Yes, the CG is proportional. Divide 14 by 18.8, then multiply by the 18.8" WS's CG. Or just place at the same point you did on the larger plane. You may want to add a tad more expo all around, until you get used to it. This little bird is very nimble at high and low speed. Good Luck on the maiden

Ksqm
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Old Apr 08, 2012, 08:30 PM
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Derby, Kansas
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Quote:
Originally Posted by ksqm View Post
Swimmer,

Yes, the CG is proportional. Divide 14 by 18.8, then multiply by the 18.8" WS's CG. Or just place at the same point you did on the larger plane. You may want to add a tad more expo all around, until you get used to it. This little bird is very nimble at high and low speed. Good Luck on the maiden

Ksqm
Those calculations puts CG at 1.675" and compared with the 18.8 looks correct. My thought is to use 35% expo because I use this when flying my other UM planes. I know expo is relative to the flyer but with your experience with the 14" do you consider beginning with 35% sufficient?
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Last edited by swimmer; Apr 08, 2012 at 08:55 PM.
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Old Apr 08, 2012, 09:00 PM
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Hampton, VA
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Swimmer,

Should be good!!! I normally go with max deflection on all control surfaces. The plane will flip in it's on length. Keeper light and you'll be amazed what you can do. I think my build was 85g AUW. Should be able to launch at 1/2 throttle. Have fun!!!

Ksqm

Ksqm
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Old Apr 10, 2012, 03:16 PM
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Originally Posted by ksqm View Post
Swimmer,

Should be good!!! I normally go with max deflection on all control surfaces. The plane will flip in it's on length. Keeper light and you'll be amazed what you can do. I think my build was 85g AUW. Should be able to launch at 1/2 throttle. Have fun!!!

Ksqm

Ksqm
My 14" came out 70g w/o battery. Just waiting for a decent day/evening to maiden it.
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Old Apr 10, 2012, 03:18 PM
Pusher jets rule!
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Mesa, AZ
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Good luck Allan! Let us know how it goes.

Pat
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Old Apr 10, 2012, 10:20 PM
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Here is my F22 hanger. A 24", 18.8" and the 14". Tape is on the wings for marking CG. Have yet to maiden the 14" and 24". Will wait for paint until have flown them a while.
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Last edited by swimmer; Apr 11, 2012 at 09:21 AM.
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Old Apr 12, 2012, 03:14 PM
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Swimmer,

Here you go. I'm also including a couple of pics. This was my "Fly Anywhere" plane. On 2S you can High Alpha and literally fly circles around yourself. On 3S it will "Boot, Scoot, and Boogie" as they say. Enjoy!!! And post pics/vids!!!
Ksqm,

The 1811 is a 2S, 7.4v motor. How long will it last on a 3S, 11.1volts?

Allan
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Old Apr 12, 2012, 03:38 PM
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Swimmer,

I still have my original 1811 I started with over 2 years ago. An it's getting ready to go into a Micro SR-71!!! Use GWS 4x?? or 4.5x?? props. I had a modified Toxic Toast F-14, about 120g-130g AUW, that I flew into the ground. It's a tough little motor. I used 3S bats from 250mAh to 450mAh. You can do a search to see what builds I've used it on.

Almost forgot. Use a Turnigy Plush 6a ESC. It's 2S also, but the only one I lost was my fault. Crossed uncovered motor leads and smoked it. I use these and nothing else so far.

Ksqm
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Old Apr 12, 2012, 04:40 PM
Pusher jets rule!
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Mesa, AZ
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Which SR are you doing? Or is it a scratch?

Pat
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Old Apr 12, 2012, 05:16 PM
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Crxmanpat,

Funny you should be asking that. I think it's an early version of jtechlaser's. I've had it cut out for over a year, maybe two. In fact, I was searching an external HD I have plans on to be sure. I wanted to make sure I have the CG right. It's the version that had just the lower cover, but I cut another set for the top. Man time fly's.

I plan to use my standard: HK 1811 2000kV motor, Turnigy Plush 6a ESC, BA 3.xx g Servos, and GWS 4.5x3 prop. Depending on batt, she'll be between 96g-120g and fast. I'm thinking it's 66% scale, about 15" WS. I'll post pics and vid in your thread.

Ksqm
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Old Apr 12, 2012, 05:49 PM
Pusher jets rule!
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Mesa, AZ
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Awesome. Yeah, Jim's and my SR's are pretty much identical, except mine is smaller.

I took the original design by Adam and tweaked it with some of Jim's design techniques.

Pat
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Old Apr 12, 2012, 08:54 PM
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Quote:
Originally Posted by ksqm View Post
Swimmer,

I still have my original 1811 I started with over 2 years ago. An it's getting ready to go into a Micro SR-71!!! Use GWS 4x?? or 4.5x?? props. I had a modified Toxic Toast F-14, about 120g-130g AUW, that I flew into the ground. It's a tough little motor. I used 3S bats from 250mAh to 450mAh. You can do a search to see what builds I've used it on.

Almost forgot. Use a Turnigy Plush 6a ESC. It's 2S also, but the only one I lost was my fault. Crossed uncovered motor leads and smoked it. I use these and nothing else so far.

Ksqm
Don't have a 2-3 Cell ESC on hand so ordered one from Heads Up. I'll fly the 14" with the 2 cell ESC and battery I have now to get a feel for how she flies.
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Old Apr 13, 2012, 05:50 PM
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14" Maiden...well, kinda.

Got my 14" out today for the maiden. I don't know if it is my 2S batteries, batteries charged, or motor placement but it just has no power. Did not want to turn right or left well at all. Flight is anemic and only 1-2 feet above ground at most.

Looking at the prop from behind the motor looks a little high so the air flow is not directed equally above and below over the tailerons. Not bad just not perfect. Should I shim it directing more of the air flow equally?

My plane weighs 69g (2.4oz). Motor is the HK 1811. Prop on with writing facing forward.

Anyone have any idea?

Allan
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Old Apr 13, 2012, 06:02 PM
Pusher jets rule!
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Mesa, AZ
Joined Jan 2006
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Allan,

You're probably going to have to bump up to a 3S pack. The Hyperion 3S 450 is a great little pack, and I used to use them all the time on the 18.8" version until I bumped up to 850.

http://www.allerc.com/hyperion-g3-cx...ck-p-4504.html

Pat
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Old Apr 13, 2012, 06:06 PM
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Quote:
Originally Posted by swimmer View Post
Got my 14" out today for the maiden. I don't know if it is my 2S batteries, batteries charged, or motor placement but it just has no power. Did not want to turn right or left well at all. Flight is anemic and only 1-2 feet above ground at most.

Looking at the prop from behind the motor looks a little high so the air flow is not directed equally above and below over the tailerons. Not bad just not perfect. Should I shim it directing more of the air flow equally?

My plane weighs 69g (2.4oz). Motor is the HK 1811. Prop on with writing facing forward.

Anyone have any idea?

Allan
I have an 11.5in F-22 (scaled down). It also has some turning problems. Whenever you try to turn left, it starts to bank and then just does a knife edge. If you increase the speed, it snap rolls. The problem was the CG was a bit tail heavy, so that could be your F-22's problem. Add some nose weight, and try again.
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