Multplex twin jet + DUCTED FAN X 2

[rc muncher]

I am reaching into the world of ducted fan units and I’m gonna start with two of them
Togther!!

I intend to take a bare multiplex twin jet (epp fuselage) reinforce the fuselage and wings with fibreglass rods the ones you get in small kites –provides flexibility, elastic properties that will allow the wings and fuselage to give way but provide enough strength to stop it tearing and bending. I am also contemplating making the wing detachable for two reasons travel purposes and secondly I may rig up the wing fuselage connection to detach on heavy landings. Will use tape on the plane to give it strength and protect against scratches and should provide a nice clean surface may make it more aerodynamic.

Then use stronger servos to allow for the added speed
Upgrade mounting on servos (have herd nightmare tales of the servo coming lose and the plane spinning into a head on with some very hard ground. wiping the plane out and making it only fit for packing material. )

Then comes the fun part adding the two little screams with 56mm ducted fan unit. Then put them in a 150mm strengthened cardboard duct (light, easy to make and replicable) with shaped nozzles. I guess my first question is mounting the fan units on top of the wings or bellow them not sure which would be best?

Second is. Will it be flyable and to what extent

What kind of thrust are we looking at? I have no experience with ducted fans

Any comments and suggests are much appreciated as want to get this thing started ASAP so I can tear up some sky.
I am going to call this thing (if it works) the Air Muncher mkI

Cheers and fly well
R. C . Muncher

[Scarey]

Skip all the reinforcement mods, airframe is stong enough. I run two HET 3w motors as a pusher with CAM 5.5 props, faster then any EDF setup. The standard HS 81 Servo`s are fine. I have flown this plane on 4S a couple of times w/o problems. Two mini fans/HET 6904 with Two 2w-20 and 4S lipo
might be faster but not much (draggy airframe and increased weight).

The setup (LS XF) will only get you 2.85 Lbs static thrust (not enough).
If you want blistering speed you will need a 700 to 1200 watt setup.
Check out the pusher forum 600 or 700 watt twin jet.

Someone has done it as a monojet one EDF but that was still slow.

[Sluf7]

this may help.

http://www.wattsup.co.nz/phpBB2/viewtopic.php?t=45

[Scarey]

Maybe a single midi fan with 1500 watts.

The one in the link is only 650 watts.

[Scarey]

One midi fan or equiv.
Quannum drive 36-55 5mm Shaft 1345kv 45A
Good 540 heat sink
80 Amp HV ESC
8S Lipo good for 60 amps cont.
will produce 2200 gm static thrust (1500+ watts)
all for $ 250 dollars US + your $ 75 dollar airframe.
Check out United hobbies.

Watched a video of a mini turbine on a twin jet had the same performace as my 800+ watt setup but sounded way cooler.

[tIANcI]

8S set up in a Twin Jet? I really wanna see how the batteries fit ... :)

[bmaaa]

You can also try a.... turbine !

With 1kg dry weight for 1,5 kg thrust, I am quite happy with this set-up :D and the sound : :D :D :D

Complete built thread + VIDEOS : HERE (http://www.rcgroups.com/forums/showthread.php?t=537867&page=5)

http://www.bmichels.com/Images/Demarage_HOT-2

[Scarey]

Lots of room for 8s bats or fuel for a turbine.

[tIANcI]

I think a TJ with a nice EDF will be a superb fun ... a 70mm fan thats screaming at 40,000 RPM? :)

[rc muncher]

i have decided to upgrade my thinking and use some of unitted hobbies 7 bladed midi fans. i want some serious power either the 3.5 or 4 inch edfs models using a Quannum 36-55 still using a twin edf setup i was wondering what lipos i have had very limited experience using twin motor setups.
and rember this has to be stuffed into a modifed multiplex twin jet---fun
secondly how the heck would u wire it all up?

Would welcome any comments suggestions or just ideas to help me with this
R C Mucher

[rc muncher]

I am reaching into the world of ducted fan units and I’m gonna start with two of them
Togther!!

I intend to take a bare multiplex twin jet (epp fuselage) reinforce the fuselage and wings with fibreglass rods the ones you get in small kites –provides flexibility, elastic properties that will allow the wings and fuselage to give way but provide enough strength to stop it tearing and bending. I am also contemplating making the wing detachable for two reasons travel purposes and secondly I may rig up the wing fuselage connection to detach on heavy landings. Will use tape on the plane to give it strength and protect against scratches and should provide a nice clean surface may make it more aerodynamic.

Then use stronger servos to allow for the added speed
Upgrade mounting on servos (have herd nightmare tales of the servo coming lose and the plane spinning into a head on with some very hard ground. wiping the plane out and making it only fit for packing material. )

Then comes the fun part adding the two little screams with 56mm ducted fan unit. Then put them in a 150mm strengthened cardboard duct (light, easy to make and replicable) with shaped nozzles. I guess my first question is mounting the fan units on top of the wings or bellow them not sure which would be best?

Second is. Will it be flyable and to what extent

What kind of thrust are we looking at? I have no experience with ducted fans

Any comments and suggests are much appreciated as want to get this thing started ASAP so I can tear up some sky.
I am going to call this thing (if it works) the Air Muncher mkI

Cheers and fly well
R. C . Muncher
midi edf

--------------------------------------------------------------------------------

i have decided to upgrade my thinking and use some of unitted hobbies 7 bladed midi fans. i want some serious power either the 3.5 or 4 inch edfs models using a Quannum 36-55 still using a twin edf setup i was wondering what lipos i have had very limited experience using twin motor setups.
and rember this has to be stuffed into a modifed multiplex twin jet---fun
secondly how the heck would u wire it all up?

Would welcome any comments suggestions or just ideas to help me with this
R C Mucher

[jonnyjetprop]

Do you mean something like this?

http://www.gworksdesign.com/Pages/CUDA1.HTML

Just think what a modern twin minifan setup (Mega 16/20/2 on 4s) could do :eek:

John

[rvincent]

2 Alpha fans and JS motors and 5 blade rotors will get you easily into the 1KW club ;) My mig on this set up with JS/Alpha 5 blade/ 4S 2200 get 530 watts. A pair of these willl get this plane moving very nicely and over 50oz's thrust as well :cool:

[Scarey]

This jet weighs 16 oz, one Midi fan with Quantum UH 1350 kV on 8S setup will weigh 2.6 lbs. AUW RTF will be 3.7 Lbs with 5.2 to 5.5 Lbs static trust.
Power to weight ratio = 1.5 to 1 (Very fast). LS setup will weigh 2.8 lbs RTF
with power to weight ratio = 1.2 to 1 but will cost more and more work since it is two of everything.

I advise you to use a midi fan and not the UH fan. UH fan has lower efflux = slower top end speed. Not sure if 8s will work with that fan snce it has 7 blade (higher amp draw).

Scarey

[Scarey]

well, I decided to take my own advice. this will be a 1500watt monojet.

[Scarey]

Well maiden today went well. Overshot landing a bit. AUW RTF was just under 4 lbs. Hand launched a little less scary than a microjet for comparison. Flew with 7S on BP hobbies 80A esc and max amps 3100 HV.

[Tram]

NIce.. :)

We need some video.. :D

Jeff
www.CommonSenseRC.com

[Scarey]

New version with 602 springair retracts. Maidened it on 8S 3100 Mah Lipo.
Flew well, very fast. Will try to get some video.
Some pics and vid of retracts.

http://www.rcgroups.com/forums/showthread.php?t=753752#post8315643

Version one w/o retracts on 7S flight Vid

http://www.rcgroups.com/forums/showthread.php?t=724271