new BVM conversion... Super Balsa Bandit... update ;) - RC Groups
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Aug 02, 2008, 06:38 PM
Tear down the WALL!
ralf dvorak's Avatar
Build Log

new BVM conversion... Super Balsa Bandit... update ;)

Ok, here we go.
This is not the start of the build log for my Super Bandit conversion, but just the inlet ducting how-to. Build log to follow, with more details on the planned setup.
I finally managed to finish my "98% perfect" workshop (pics to follow, too) and now finally got started on this ones' basics, while being away too much for work (LOTS to fly, plus just in the process of getting the 4th stripe back...)

Inlet/FSA is exactly 90% (of a DS-94) so we're about ideal there... then the inlet ducting has to be ala EB, but a little more bent for increased batt room and to clear the BV style blade spar.
This is a standard BV Super Balsa Bandit, bought off RCU as a go-fly package, but unfortunately started. The builder ran a bit amok with the aeropoxy glue gun...

So, I shaped the ducting by the inlet template and a half circle/120mm dia as a straight-shot, the area increasing constantly, with the plug about 10% longer than necessary.
Next came out the big Hacksaw... thick metal blade in it. I sliced the plug through about 3/4s of the way (evenly!), every 8-10mm or so on the respectice OUTside of the bend. Then I cut balsa spacers, about 1cm wide, 5cm long, of 1, 1,5 and 2mm balsa sheet.
By inserting the spacers of various thickness I could finely adjust the bends' curvature... adjusting them IN the fuselage and getting them even and stable enough to be pulled out several times took the aide of a few pushpins (through the balsa spacers in between the slices)and a few sharpened kebab sticks (through the foam slices)
Long story short: here are two inlet ducting plugs in the raw, evenly shaped (eyeballed by holding them next to each other, but I guess they're not further than 2-3mm apart now, and I will take care that they get closer when filled, glassed, filled and polished
Next step was to fill the gaps in the foam with a mixture of EP and microballoons, brushed on and pressed into the gaps (hotel key cards are perfect ) and then let cure.
In the meantime they're sanded and the remainder of the gaps filled up... tomorrow final sanding, gaps checking, spar/former clearance, etc.

Stay tuned!

Last edited by ralf dvorak; Feb 22, 2009 at 12:32 PM. Reason: update
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Aug 03, 2008, 09:36 AM
EDF rules... :)
AirX's Avatar

Was that your F-16 in the videos posted on Herbs thread? The color Scheme looks the same. Sure flew well and lots of authority.

Eric B.
Aug 03, 2008, 03:46 PM
Tear down the WALL!
ralf dvorak's Avatar


Hi Eric,
yes, that's mine, and that's me flying it, I'm the guy in the green T-Shirt

further on the SBB inlet plugs:
today I sanded them and equalled the contours a bit more, they're symmetrical enough for my taste... after I took the pics attached I applied two layers of glass, further putty/filler after that to come.
The alu disc is exactly 120mm dia, cut in half, checked with an empty shroud. The strip in the middle is in fact two strips of 0,6mm glass to replace the thickness of the saw cut. They're glued to the end of the plug to serve as the rear sanding template. The plug-in-flange will be glued on top (124,5mm dia in half) to create the fan shroud plug-in step, in my usual technique (EB, P-80, etc.)
More next week, gotta go to work this week...
Aug 04, 2008, 03:42 AM
smug in granny panties
monkamarm2000's Avatar
looks great ralf! I just finished a set for the bandit, forst one is a heavy pre built turbine but got a nib one untouched for second one. It was a pain though cause reg bandit has those tiny inlets.

Aug 04, 2008, 04:50 AM
The blade numbers go up to 11
stumax's Avatar
Mmmmmmmmm, don't ya just love sanding foam and filler! Somebody's gotta invent a robotic arm for that sooner or later. How much power's going in this one, Ralf?

Aug 04, 2008, 11:18 AM
Tear down the WALL!
ralf dvorak's Avatar


Stu, it's not that bad... the green foam sands really nice by hand with 80grit and the EP has 200% microballons in it, it sands nicely, too. For coarse works I have a nice tool:
see also attached pic.

The glass is on, cured, looking good and I'm gone for the week now,
cu all,

Aug 13, 2008, 07:17 PM
Tear down the WALL!
ralf dvorak's Avatar


...hi all,
here's the latest.
The plugs received a coat of microballoon resin each, and I sanded them to the final shape, tried to make them symmetrical as much as I could and I think it's ok. They're not JR CNC cut but I don't think one would notice once installed.
Then they got the first layer of filler, just for contrast and to spot pinholes. The first 2k filler layer is just curing.
Next I turned a bellmouth from green foam to test the anticipated setup outside. The foam is secured to the fan and covered in lengthwise strips of sellofilm and wrinkles shrunk away with a heatgun. Ideal conditions there... we'll see. I cut down my old P-80 thrust tube to be attached (92mm nozzle) to give it a realistic environment. Testing should commence at the weekend.
I'll keep you informed.
Aug 26, 2008, 08:47 PM
Registered User
maverick pro's Avatar
rd...nice to see another bandit conversion. the ducting looks good, nice work.

barry...i got the bandit and cant thank tam and you guys for my nice new inlet ducting. cant wait to get the fan setup and finnaly in the air after 2 years. i did do some more dieting with the bandit but without changing the gear i cant get any lighter than 12 lbs....yeah heavy . but i think the fan on 16 cell will do fine.

thanks again
Sep 25, 2008, 07:02 PM
Tear down the WALL!
ralf dvorak's Avatar

et violā!

two near perfect inlet ductings... they're just curing in the heated chamber.
They're one layer of 49g/mē glass, two layers of 163g/mē carbon... to withstand the sucking power of the fan. The fan I use has some ... the claimers don't have to worry about that.
I had the anticipated setup on the test stand the other day...6kW and 10kg+

more soon,
Sep 25, 2008, 07:57 PM
Build'em and Crash'em
Ken Lapointe's Avatar
Dam Ralph your duct work is amazing, if only my planes could look that good.
Sep 25, 2008, 08:04 PM
Registered User

I am new to this blog! I am looking for anyone that has built or who might be building the Fairchild A10. This is a scratch build plan. I have the plans, but I am seeking information as to a parts list and questions on the fan units. I have seen "unclecrash" blog sheet on this plane. If anyone knows if he is still on RC Groups, could you lead him to me.


Sep 25, 2008, 09:28 PM
Suspended Account
k_sonn's Avatar
Hey Ralf,

That ducting lookds awful. You should send it to me and make a new set

Seriously, the ducting looks awesome.

Sep 26, 2008, 02:41 AM
smug in granny panties
monkamarm2000's Avatar
very sexy!

Sep 26, 2008, 07:59 AM
Registered User
JB's Avatar
That's the way to go!
6kW and 10kg+ Wow
Sep 26, 2008, 12:02 PM
Registered User
flo's Avatar
Hi Ralf,
very nice work indeed.

wish i had your skills - so i could get my d..m duct done.
Kinda stalled on the A6 at the moment as Robert doesn`t get the LG done and Ronny still hasn`t done files on the duct work.

10+ kg sounds awsome.



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