iceman3, I know little about the 300DF motor you're using. If it has a high enough Kv to put out the power you need with the props you suggest, then you should be good. Those prop sizes are very close to the stock size for the MJ, so the torque roll shouldn't be significantly worse (with more power it will get a bit worse, but then again you'll get better acceleration so there will be more chance of recovery as the control surfaces become effective more quickly).

I'm no expert on the MJ, so I'll wait for someone else chime in.

-Flieslikeabeagle

I'm flying my MPX Micro Jet with the following

3 cell 2100mAh Lipo
16/15/7
APC 7x5 E prop

Only pulls 9.5 amps static off the charger and the total weight is 15 ounces on the nose. It's not a blistering rocket ship but is pretty darn fast! Goes vertical no problem.

It has very gentle stall characteristics. Pull off the power and it just poropuses along, landings are slow and gentle.

Flies inverted very well, probably the best of any flying wing i've flown.

I fly a bit of slope also and don't see any reason why it woulnd't fly well there either.

Todd
www.toddsmodels.com

Yup,
I just sanded the bottom of the wing before I carbonfibered it, to strengthen it. Butch

I have a micro jet that I destroyed 3 times and it still flies. The nose looks like the concorde. With enough power anything can fly.

The answer to launch problems seems to be a catapault/bungy launcher like the one at:

http://www.geocities.com/stormeflyer...cher.html20052

I'm in the process of designing/building mine at the moment, based loosly on this one. Mine will have a bit of a ramp built in rather than flat like this one.

Cheers

Numb Thumbs

PS I'll let you know how mine goes!

hey thumbs, that page dont work

Take off the numbers:

http://www.geocities.com/stormeflyers/launcher.html

Cheers

Numb Thumbs

Well i flew it this morning with the 3 cell packs and made a big difference. hand launches much better and goes like heck.

i got micro jet the other day and i built it in an hour whilst watching TV ( very easy) and i ditched the 400 and put a 480 in and i am goint to use 8 cells and the Graupner push on prop that came with it. When testin the motor at full my tacho reads around
345 how many RPM does thi equate to 3,450? And how much does a 400 on 8 cells with a Grupner prop give. Can't wait to fly

Flying Scotsman I'm not sure about your RPM question but I'll tach mine tomorrow and see.
I have a few hours flying this model now and its a lot of fun to fly. Zips right along even at half throttle. Hand launches are touchy but I have the hang of this one now. I've modified the canopy hold down to use Radio Shack rare earth magnets and that works much better then the stock clips. With my setup, (stock motor, pixie 20 esc, HS81BB's, GWS receiver, 3 cell 900mh lipos) I need just a bit of lead in the nose.
Yesterday I gave it a camo paint job, heres a pic

Here are my numbers for a 16/15/4:

Mega 16/15/4 / 3S 2200 mAh / 18 Amp ESC
Propellor Thrust gms RPM Amps
Graupner Speed 4.7x4.7 430 19200 13
Graupner Speed 5.2x5.2 500 16500 17
Graupner Speed 5.5x4.3 630 18000 16
Graupner Slim 5x4 640 17200 18.5

APC 5x5 400 18000 15.3
Generic 6x3 560 16500 19

Cheers

Numb Thumbs

Originally Posted by kdk

I flew mine for the first time this morning and it's real hard to hand launch. it seems very underpowered. I'm thinking its because im using 2 cell 1320 TP packs instead of 3 cell packs maybe. I'm using the stock motor and prop too. I had a friend give it a good right handed toss and with me already on the sticks it flew away ok and flew real nice once it got going.

kdk

2 cells is far to low You would be better with a 7.2 volt 480 motor and a 3 cell pack of around 2100 mah. If you are using the stock 6 volt motor 3 cells will make it go very well but will burn out the motor after say 10 - 20 flights

Hi all

I finally got to put the MJ together with the Justgofly 300DF motor. Yesterday the weather was good enough to give it a try. The setup was as follows, 3sp Etec 1250Mah, camspeed 4,7x4,7 prop, cc Phoenix 10 and the weight came out about 300 grams. On the maiden I had my doubts because I am used to a 660 grams MJ with Mega 16-15-3 motor and heavy PQ 3sp 2600 Mah packs. I worried for nothing, the plane almost went vertical out of my hand on 3/4 throttle and a it was a delight to fly. I didn`t think handlaunching the MJ could be so easy. With the Justgofly 300DF motor I got about 10 minutes of flying with some throttle management. This motor is very silent and you could only hear the prop working from distance. I am very pleased with this setup and the speed is very good, since I don`t have a radar gun it`s hard to say exactly but 80-90 kmh straight and in a shallow dive it will go a lot faster, but I was to nervous to try low passes on the maiden to check it out. The one thing that surprised me was that it wasn`t ducking in high speed, and i figured out it must be because I mounted the motor with a L bracket and it is seated about 5cm outside the body with lots of air for the prop to work with. All in all a great setup for the MJ.

Hi iceman3,

that is real cool. do u have pics of the mount?
Thanks.

casioppc

I don`t have a digital camera but I will get one pretty soon so I can take some pics and maybe a little video. I can try to explain the mounting in words, but a picture say a lot more. I prepared the motormount/Lbracket with drilling holes for the motor with the standardmounting that follows as a guide. Then I made 4 slots in the Lbracketfor the tiewrap with a file. About 1cm deep so that the tiewrap would get a good hold. I used the standard mounting holes in the MJ frame and thats it, pretty easy with a good drill and a file. I have thougth of a setup with mounting of the engine outside the body for a long time, because i got those strange sounds from the prop in high speed turns, and later I have heard that it is because that the prop looses air to work with. With the motor/prop about 5cm outside the body, it seems that this problem is gone. I must say I am surprised that this tiny little motor can pack so much power, and because of the weight reduction from my former setup it is much like night and day to fly and not to forget handlaunch.