"Official" BH/LX B-2 Stealth "Spirit" 2x64mm EDF, Build/Mods Thread! - RC Groups
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Sep 12, 2009, 04:59 PM
RemE's Avatar

"Official" BH/LX B-2 Stealth "Spirit" 2x64mm EDF, Build/Mods Thread!

Hi All, I thought I'd try to start my first build/mod thread. I'm doing this with the hopes of keeping an independant organized discussion on this B2 model.

NOTE - I will Update this first post with links to helpfull items found along the way. If you decide to post your build here, may I suggest that you start a post with your build and then bookmark it. As you make changes along the way and post to the general thread, that you also go back to your bookmark and update that original post as you update your build. I will post a link to each persons build post here on page 1 which will give folks a good one stop place to easily see nice and complete builds.

Suggested Tips to insure a successful flight (will add more as this thread develops);

1 - Double check the control horns!, possibly re-glue to insure the drag rudder horns won't come loose in flight (sudden and immediate loss of control seems to be the first symptom of a failed drag rudder in flight).

2 - Gear collapse is fairly common, make sure the stock landing gear locks down. You may have to unbolt the gear to get to the push rod and bend the rod to archive the proper throw.

3 - Check steering servo. Make sure it doesn't hang in random positions, the clamping band that hold the servo in place could be to tight. So tight that it deforms the servo casing and destroys the guts of the servo.

4 - Set up as Delta Wing mix.

5 - Insure both drag rudders are both exactly the same. When open make sure they are open the exact same on each side, do this for the full range of motion.

6 - More to come.


Purchase Link Banana Hobbies Airframe Only; http://www.bananahobby.com/1890.html
Purchase Link for Banana Hobbies RTF Version; http://www.bananahobby.com/1886.html
Purchase Link for purchase in Germany; http://www.xpowershop.de/

Original BH Thread, closed due to pre-release meyhem; https://www.rcgroups.com/forums/show....php?t=1059925

Bananna Hobby's Demo Video;
B-2 Spirit! Stealth Bomber RC JET Flight Review in HD! Twin EDF RTF B-2! bananahobby.com! (10 min 1 sec)

Video of a Stock B2 Maiden Flight, good headcam video; https://www.rcgroups.com/forums/show...&postcount=341
Some nice pics, 2 Flight Videos and a B2 History Vid; http://www.msfc.jp/kenmamuya/contents.cgi?d=C1500
Original Flight Video, probable crash; http://zoome.jp/fuga3500gtfour/diary/158
Original Flight Video with Hot Landing; http://zoome.jp/fuga3500gtfour/diary/162
Hepdogs B2 "crosswind landing challenge" flight example; https://www.rcgroups.com/forums/show...59&postcount=1
Lushlife's maiden video; https://www.rcgroups.com/forums/show...3&postcount=57
Lushlife's 2nd day out; https://www.rcgroups.com/forums/show...8&postcount=71
Aero65's solid flight with yaw Gyros; https://www.rcgroups.com/forums/show...&postcount=473
Kenji Hamamoto's Functional Drag Rudder Airbrakes, over water!; https://www.rcgroups.com/forums/show...&postcount=476

Airframe Only Build Links;
RemE's Airframe Build; https://www.rcgroups.com/forums/show...94&postcount=3
Hugget's Airframe Build; https://www.rcgroups.com/forums/show...8&postcount=27
Lushlife's Build; https://www.rcgroups.com/forums/show...8&postcount=71

Stock ARF Build Links;

Please try not to make this a Banana Hobby bash thread if you can resist, they do their best. Let's get some good flying builds going and help each other!

For starters, here's the original Glam Photos from Pete at Banana Hobby.
Last edited by RemE; Feb 04, 2010 at 04:24 PM.
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Sep 12, 2009, 05:00 PM
RemE's Avatar
Here's an overview of the airframe only ARF Kit.

The overall finish is very good, my luck, got one with a paint flaw on one outer panel... Water decals are included on a big sheet.
Last edited by RemE; Feb 04, 2010 at 04:27 PM.
Sep 12, 2009, 05:01 PM
RemE's Avatar
My Build! This post will be updated as I progress and make changes.

I'm looking things over and deciding what to do with linkages etc. I will not be doing a stock build. The motors will either be Don's cool wind 4000Kv or EFlite DF480's in EDO 5 blade fans.

I've now spent many hours programming my 14Mz transmitter and I've decided to go with 12 servos on 12 seperate channels, so the wiring will be simple at least. I've got a nice mixing setup that will allow a serious "Crow" configuration of the surfaces to slow this thing down, individually adjustable retract servo channels with delay, seperate steering channel, manual and gyro control of the drag rudders for use as rudders and stabilizers, and manual opening of them both as drag brakes.

I will be re-working how the drag rudders operate to give solid accurate opening of the top and bottom surfaces.

Radio, 14MZ, 12 servos on 12 channels, no Y cables.
Ch 1 - Left drag rudder.
Ch 2 - Rt drag rudder.
Ch 3 - Throttle
Ch 4 - Left Outboard Ail
Ch 5 - Rt Outboard Ail
Ch 6 - Nose Steering
Ch 7 - Left Inboard Flap
Ch 8 - Rt Inboard Flap
Ch 9 - Bombay Doors
Ch10 - Left Main Retract
Ch11 - Nose Retract
Ch12 - Rt Main Retract

Motors - 2x E-Flite 480DF 4000Kv outrunners
Fans - 2x Don's EDO units.
ESCs - 2x Castle ICE-Lite 50's, I will be using 9A Schottky diodes (Vishay P/N 95SQ015) in the plus lines to the RX to allow redundant power supplies.
Battery - 5000mah 30C FlightMax, 521g (18.4oz.)
Gyros - 2x GWS PG-03, 1"x1"x.5", 7g Piezo's

After going thru all of the included hardware, it appears that no screws or backplates are included for the Drag Rudders. They provide 8 control horns, 4 backplates, and 8 screws. This will handle the elevons but leaves you with only horns for the drag rudders.

Because the drag rudders are not that thick (about 1/4"), I will use round toothpicks, that wedge nicely in the horns and surface holes, and glue with 30min epoxy.
Last edited by RemE; Dec 28, 2009 at 12:50 PM.
Sep 12, 2009, 06:17 PM
congrats,i wish i had one coming.is this the airframe only
Sep 12, 2009, 06:27 PM
RemE's Avatar
Yup this is the airframe only, If I'm going to put some love into this, I want to pick the components. But I do want to hear about how a stock one works out!
Sep 12, 2009, 06:47 PM
i agree 100%.im waiting on esc's and batt for my sapac f22 twin airfram only
thin i have a big decision to make on my next bird.i want another f18 but,i could swap electronics and put them in this.im glad i will have time to see how these b2's will work.i envy you my friend liooks like alot of cool stuff to
work on.good luck and enjoy. anthony
Sep 12, 2009, 10:18 PM
Registered Plan-a-holic
Hepdog's Avatar
WOW that is a nice chuck of foam.

I'm not seeing any slots for spars of any kind??? Does it rely on foam only? Not that this is a bad thing - but I like spars on flying wings.

The crow set up could be very useful. I always found mine to be a bugger to get down and slow down - landing approaches had to be very long and flat - not always an option.

I'm also very curious how the drag rudders opened with just a single servo if the linkages were on the outside??? I used a single servo but on the inside.....

Good of you to post so many pics. Thanks.
Sep 12, 2009, 10:34 PM
RemE's Avatar
I'll post up the stock drag rudder setup and if you have any single servo suggestions I'm open! The surfaces are thick enough that it may be possible to do an internal horn setup, hmmm.

There is no spar but the wing root is very chubby (it's about 1 1/4" thick at this joint and the foam is very dense) so I guess it's not needed.
Last edited by RemE; Sep 12, 2009 at 11:27 PM.
Sep 13, 2009, 01:19 AM
Registered Plan-a-holic
Hepdog's Avatar
OOOhhhh I see.

The stock way is not the way I would do it BUT it isn't a primary control surface used alot so any flex issues shouldn't be big....although if you get more top rudder deflection than bottom there is an accompanying pitch up. Not a huge issue but annoying all the same. Mostly only noticeable at higher speeds when the loads are higher.

I think you will be surprised at how effective the drag rudders are. Only need to open them a bit to pull a wing back.
Sep 13, 2009, 01:25 AM
Registered Plan-a-holic
Hepdog's Avatar
Here's pics of how I did mine. My wing was thick enough to house a single HS55 internaly and the hinge lines were far enough apart to get some decent leverage. It's a PITA to set up and maintain but looks good.

I think the stock set up might actually be better than trying to go internal. It really is very hard to access later on.
Sep 13, 2009, 09:10 AM
Registered User
Joe 1320's Avatar
It certainly looks stout enough to not need a spar. How dense is the foam?
Sep 13, 2009, 01:58 PM
RemE's Avatar
Hep, looks like we are on the same page. Here's my scribbles from last night where I was thinking about internal vs external linkages. While I love to tinker and prefer the sleek look of internal linkages I decided to go with the external linkage to keep it a little simpler and spent more time making a scale drawing.

It will still be a little challenge as the linkages will be short. The servo arm will go inside the wing and the pushrods will have to cut in at a steeper angle. This will give the top and bottom surfaces solid control. Since the links only pull under tension I'll be using small dia piano wire.
Sep 13, 2009, 02:00 PM
RemE's Avatar
Originally Posted by Joe 1320
It certainly looks stout enough to not need a spar. How dense is the foam?
The foam seems very dense, very little "bead" look on the surfaces.
Sep 13, 2009, 02:02 PM
RemE's Avatar
Thought I'd add this note from the previous thread from Hepdog regarding general B2 characteristics (BTW, I measured this B2 at 110 degrees);

"First someone needs to get their hands on one and measure the angle the wing LE's make on the nose. My big one is 110 but I've flown 90's as well. This really changes how they respond so I'm interested to see where Bananna went.

Next is careful attention to the CofG. Depends on the angle of the wings and how much extra area he added, but the CofG is super critical because that determines how much REFLEX needs to be in the elevons. Just like all flying wings, it needs reflex to fly right. I think the reflex also adds a stabalizing effect to the model as well.

Other than that, all of mine have been pitch senistive and roll sluggish. I fly with a standard elevon mix in my radio (Futaba) and put in -40% on the elevator, 0% on ailerons and 0% on the rudders.

I don't use gyros and really don't see a need - mine flys so heavy in roll that you have to hold inputs for quite a while (compared to a 3D machine). A gyro on the rudder channel might be interesting and better at preventing PIO, but I've just gotten use to a little natural arse wiggle. Dunno bout that one - if the rudders are set up right they shouldn't cause any pitch change when opened/closed but if not set up right ...a gyro opening/closing them without pilot input could actually get uncontrolable pretty quick - if open pulls the tip back and causes a rolling moment down then the PIO effect could set up a nasty cycle...or not.

Mine has no landing gear so I can always land directly into the wind. I've flipped her twice on landing because a crosswind got under one wing - once it starts to go over that low there is nothing you can do but watch and laugh...cry. Full opposite won't stop it cuz there is some really weird aerodynamics going on."
Last edited by RemE; Sep 13, 2009 at 02:11 PM.
Sep 13, 2009, 05:48 PM
RemE's Avatar
After going thru all of the included hardware, it appears that no screws or backplates are included for the Drag Rudders. They provide 8 control horns, 4 backplates, and 8 screws. This will handle the elevons but leaves you with only horns for the drag rudders.

Because the drag rudders are not that thick (about 1/4"), I will use round toothpicks, that wedge nicely in the horns and surface holes, and glue with 30min epoxy.

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