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Dec 09, 2019, 06:43 AM
EB-66C Team Member
J Morgan's Avatar
That "partial" cockpit looks great Ken! Nice job!

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Dec 09, 2019, 10:37 PM
Classic jets rule
AIR SALLY's Avatar
Quote:
Originally Posted by Dirty Dee
Looking great!

With your model being a C variant, I noticed something in various pictures and models for you to consider adding to your airframe.

Comparing the A vs the C, the C has a small angled fairing (not sure what the right technical name is) at the root that blends into the fuselage. Looks like the mold and plans dont have this included as part of your build.
That is called a LEX.....leading edge extension.
Dec 10, 2019, 04:10 AM
Big gov never Works
St. Martin's Avatar
It could cause a shift in the cg, if added as an after thought. The CG may need to move forward. Also, it may change the relationship of the root and tip airfoils, if mechanical and/or aerodynamic washout is used. Just a thought..

Fuzz
Dec 10, 2019, 10:01 AM
Registered User
Dirty Dee's Avatar
Thanks for clarifying Air Sally
Dec 10, 2019, 10:48 AM
Registered User
Remembered reading somewhere (Aerodynamics for Engineers?) that when it was added to the F-5G it added something like 18% of lift. Understand it generates a conical vortex at the wing roots that delays detaching of airflow, thus stall. Does that mean it increases the critical angle of attack? Perhaps some of you aero whish can help explain? Popcorns & smiles.
Dec 10, 2019, 11:15 AM
Build'em and Crash'em
Ken Lapointe's Avatar
Thread OP
I scaled the LEX out and its all of about 3 by 2.75 inch triangle. While it may have some effect it will probably be minimal when compared to the wing tip tanks, those things are huge. I also figure they must have put them on the C version for a reason. I just need to see how hard it will be to add them on. I would need to add parts to the wing and also to the fuse because of the way the fuse has the root molded in.


Did some painting and finished up the cockpit. Pilots are from Benchmark RC.

Of course looking at the pictures now I see a few areas that need to be touched up.
Dec 10, 2019, 12:10 PM
Pro Hoarder
turbonut's Avatar
Cockpit is looking great..That is a big canopy to fill up so it needs it.
Latest blog entry: In flight
Dec 10, 2019, 12:13 PM
gravity tester's Avatar
Hi Ken-
Been silently stalking the thread for a while and she is really looking great. Do you have a link for Benchmark RC you can share? My search has come up empty but I am probably spelling "RC" wrong or something. Thanks!
Dec 10, 2019, 01:08 PM
Build'em and Crash'em
Ken Lapointe's Avatar
Thread OP
Quote:
Originally Posted by gravity tester
Hi Ken-
Been silently stalking the thread for a while and she is really looking great. Do you have a link for Benchmark RC you can share? My search has come up empty but I am probably spelling "RC" wrong or something. Thanks!
https://www.rcgroups.com/forums/show...ilot-full-body

https://mhartfab.wixsite.com/benchmark-rc
Dec 10, 2019, 07:26 PM
Build'em and Crash'em
Ken Lapointe's Avatar
Thread OP
Well its a Navy carrier trainer so I guess it needs a tailhook. Was gonna make it out of wood but did not look forward to trying to drill lots of holes in a straight line, so I broke out the CAD and 3D printer.

I'll need to make a few tweaks to the first draft. I have to add a section to the back of the tail wedge to mate with the pivot and need to change the hook shape. Also need to figure out how to make it easy to attach and remove.
Dec 10, 2019, 08:47 PM
go fly! no crashes!
Synwpn's Avatar
Looks good Ken!
Dec 11, 2019, 02:32 PM
Build'em and Crash'em
Ken Lapointe's Avatar
Thread OP
Did the weigh in today for weight estimates and battery placement.

Airframe weight as is with servos, fan, esc , etc is 11.6 lbs.

Throw in 2x6S 6000 packs and its RTF weight before finishing is 16.5 lbs

I'll estimate another 2 lbs for paint, decals, linkages, servo wires, tail hook. So I'll estimate the completed plane at 18.5 lbs.

At 5Kw thats 270 Watts per lb, which should be fine for a jet trainer.

Battery placement ends up being 1 pack right in front of the spar and 1 right behind it. Now I just need to make some battery trays.

I did weigh the duct work, some actual weights, some calculated by the 3D printing software, but verified by what I could weigh.

My ductwork comes in at 10 oz. The kit fiberglass parts come in at 6oz, but still need the seams glued and taped along with carbon fiber tow, figure another 2 oz. So my plastic comes in about 2 oz heavier. I'm fine with the slight weight increase as I think the printed ductwork is much better.

I could lose 7.5 oz by deleting the cockpit and pilots, but what fun would that be.
Dec 11, 2019, 04:14 PM
Pro Hoarder
turbonut's Avatar
I bet the wing loading isnt too bad and that has a big high lift wing so it should fly great
Latest blog entry: In flight
Dec 11, 2019, 04:25 PM
Registered User
Castel101's Avatar
Looking good Ken, thanks for the data on the ducts weight!
Dec 12, 2019, 09:14 PM
Registered User
70 ragtop's Avatar
Looking good Ken! The weight adds up so fast, but I agree it's going to fly great!
You're doing a JF100 with a 780 motor? I think that setup would be pretty happy on 14S, the stick on the left can always be used for slowing it down
Little extra umph is always nice, especially for us grass flyers


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