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Old Jan 27, 2013, 07:40 PM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
4,430 Posts
Build Log
E-Scorpion

Thought I would try my hand a building a foamy, need a project to do while I rehab. The pic below gives you an idea of shape. Some preliminary numbers.
WS=52", L=61.5" Power=JF90/Het 700-68-1200Kv on 12S. Wing area =715sq.in. Retracts, with ailerons, flaps,split elevators, rudders. Component weights come to approx 6.5lb. I asked J Morgan to guesstimate a weight for a fuse, his guess, approx 4.5lb. Also, there should be some additional lift due to the large bottom area. I should see around 11.5lb thrust/and approx 4.4-4.5Kw.

So I am looking at around 11lb, will try to lighten it some! Better than a 1:1 thrust ratio, and approx 400+W/LB. Wing loading is a little higher than I would like, but I think back about C/N's JHH-F-86, I think it was 13lb at 3500W. C/N, correct me if I am wrong!
Plans are drawn, templates cut for wing, stab and tail cores.

Just thought I would run this by you guys before I start any building. I know this is just asking for it, but any thoughts or opinions.

Addendum: In talking with some other members of RCG, they wondered about my numbers. Just for comparison, lets use the Y/A Starfire, specs are close.
Specs:
Length:......................62 1/4"
Wing Span:................50 1/4"
Wing Area:................620 sq."
Weight:.....................10-11 lbs
I seriously doubt that any actually came in at that weight all dressed out. And yet they flew very well on the OS91/Dynamax system, with possibly less thrust than my proposed EDF set-up. All things considered, I think I'm in the ballpark.
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Last edited by CoolerByTheLake; Mar 11, 2013 at 11:56 PM.
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Old Jan 27, 2013, 09:32 PM
Air Assassin
RogueAce's Avatar
United States, FL, Pompano Beach
Joined Oct 2012
353 Posts
I will be watching !!
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Old Jan 28, 2013, 12:26 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
2,946 Posts
Quote:
Originally Posted by RogueAce View Post
I will be watching !!
Ditto!
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Old Jan 28, 2013, 08:02 AM
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Denver CO
Joined Apr 2008
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Old Jan 28, 2013, 07:53 PM
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unclecrash's Avatar
white lake michigan
Joined Oct 2004
3,650 Posts
D you keep slobbering like that, he's gonna need floats to get this plane of the pond
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Old Jan 28, 2013, 11:14 PM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
4,430 Posts
Here's the intended project.

Specs from the Aviation Design site.
Model
E-SCORPION
Span - 49’’.....Length - 59’’
Weight in EDF version - 7.1 lbs without batteries, 9.3 lbs with batteries
Fan -1 fan 90 mm, 3 kg (6.6 lbs) to 4 kg (8.8 lbs) thrust
100 A controller
8S or 9 S lipo pack, from 3400 to 4400 mah

If you read the first post, I threw most of these specs out. Had to be some what bigger. My specs:
Span-52" ...Length-61.5"
Weight with batteries--approx 11lb
Fan- JetFan90/Het 1200kv approx thrust 11.5lb/5.25Kg
120A ESC
12S-5000, 35/70C
Also added, Flaps, and rudders.
The bulk of my extra weight is in the batteries and additional servos.

I'm not in a big hurry on this, so no build thread. I have the core blanks, hot wired out, but left the wing panels over size in case this doesn't work as planned, I can use them later. And a whole bundle of FFF, to experiment with! 25x2'x4' pieces. I have no illusions on how this my pan out.. This may be harder than making a composite fuse! I'm no John Morgan or a humbertomelo.

I recall seeing the Scorpion years ago and thought it was rather unique. Had seen Hoover or die's build on this, thought I'd give it a try. Link to his thead below.
Scratch-Built Mini Scorpion 60"L X 44"W
http://www.rcgroups.com/forums/showt...ght=e+scorpion

Not to much to show, but alot has been done. As mentioned core blanks cut, airfoil templates done, all measurments scaled out.
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Last edited by CoolerByTheLake; Jan 29, 2013 at 09:38 PM.
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Old Jan 29, 2013, 05:49 AM
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Denver CO
Joined Apr 2008
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Dreams do come true, if you work on them hard enough.
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Old Jan 29, 2013, 11:19 PM
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St.Catharines, Ontario
Joined Jan 2009
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love the shape. deffinitely subbed.

Rich
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Old Jan 30, 2013, 12:41 AM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
4,430 Posts
Well I have made my selection on the servos. Based on torque, size, weight, reliability, and of couse cost! I have chosen to go with Hitecs. Some will cringe, but if they want to pay for JR's I will more than gladly accept! It's all I can afford!!!
All have gotten excellent reviews.
Looking at:
(5) HS-225MG's--Ailerons, elevators, steering
(2) HS- 645MG's--flaps
(2) HS-82MG's--rudders
(1) HS-81---retract's
At 6V's

I had said back in post # 6, I wasn't going to do a build thread, but I may change my mind. I had no problem in making the fuse for the Sabre, (I knew I could do it) but I'm alot more apprehensive about doing foam!! The bar has been set pretty high!

Still working out some details. A fair amount of things to order, yet. Just have to wait for tax rebate
.Missed the delivery of the motor I orded from Effux Rc, didn't here them at the door. Set-up re-delivery for tommorrow. Disappointed to say the least!

That's all for now.
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Last edited by CoolerByTheLake; Jan 30, 2013 at 01:18 AM.
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Old Jan 30, 2013, 01:04 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
2,946 Posts
Quit stalling You know you want to do a build thread,we all want you to do a build thread, it's a done deal.
Looking forward to your build,even if you decide just to do an occasional update type thread.
Stuart
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Old Jan 30, 2013, 07:41 AM
Air Assassin
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United States, FL, Pompano Beach
Joined Oct 2012
353 Posts
Exactly what I told him Stuart !! We don't care if it's a year long build...we just want to watch it come together.
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Old Jan 30, 2013, 09:08 AM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
4,430 Posts
You guys are encouragable!!! BUT, I better get my arse in gear here, and get my taxes done, or there will be NO MONEY to do the build!


UPDATE, 12.40PM
TAXES are FILED!!! There will be money for the build.
Lets do a happy dance!


2nd UP DATE, 2:55 PM
Things are looking up, USPS just dropped off the motor I ordered from Efflux RC. Gary did a nice job extending the leads. As the driver didn't see a vehicle in the driveway, she thought no one was home. I did warn her that in the next couple of weeks to expect more deliveries!!!
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Last edited by CoolerByTheLake; Jan 30, 2013 at 02:59 PM.
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Old Jan 30, 2013, 06:22 PM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
4,430 Posts
As many times as I have went to the Aviation Design site, I missed this little ditty.
- Very easy to fly.
- Short take off and landing due to big airfoil thickness (13%),large flaps and low wing loading

With total disregard , I picked, what I thought "looked good" for an airfoil. Below is the 9.5% I choose, compared to a 12% one, considerable difference. Back 6" from L.E. max thickness is 2 9/16" on 12%, on the 9.5% its 1 13/16" I can only guess how much thicker a 13% would be. May have to look into a change.
One thing at a time. Any suggestions for the airfoil? Not to late to make a change.

Mounting the fan and wing pose its own problems. Ducting goes over the wing, that can be delt with. With width of fuse, fan formers will be long. I plan on using lots of 1/8th" 6-ply here, also on wing spars, and stab mounting. Have an idea here for that. Bud Nosen's business is just out of town (30mi) and he has a great selection of wood. The LHS gets a lot from him, thinking special order. As cold as it is up here, not much chance for wood to warp! Looking at -20 Fri AM.

Now with tax refund on it's way, time to start finalizing my " list" of goodies. That still gives me a good week to do it, then wait for parcels to start rolling in!!

With the prodding of RogueAce and Stupot46, I guess I need to get some new batteries for my camera. Looks like I will be taking lots of photo's!
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Last edited by CoolerByTheLake; Jan 30, 2013 at 06:34 PM.
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Old Jan 31, 2013, 01:22 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
2,946 Posts
Looks like we have a result folks! Let the "creativity"commence!
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Old Jan 31, 2013, 01:22 AM
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p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,195 Posts
How long is your root and tip cord and what is the sweep or angle. Also need panel length. Is the wing build up or a core? I prefer to use the RG14 or RG15. What is the max thickness that can be used?
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Last edited by p901P901; Jan 31, 2013 at 01:28 AM.
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