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        The Mpx Micro-Jet has arrived! (Part II)

#1 flieslikeabeagle Jun 05, 2005 03:45 AM

The Mpx Micro-Jet has arrived! (Part II)
 
This is the continuation of "The Mpx Micro-Jet has arrived!", part I, which can be found here:
http://www.rcgroups.com/forums/showthread.php?t=96321

#2 flieslikeabeagle Jun 05, 2005 03:48 AM

Let's get this Part II thread rolling:

Has anyone tried the Micro Jet as a slope soarer? With the good aerodynamics of the airframe, and a low AUW (no heavy motor or large battery pack to carry) I would think it would perform well. The tough Elapor foam would be icing on the cake.

-Flieslikeabeagle

#3 Numb Thumbs Jun 05, 2005 03:50 AM

I haven't yet, but I must give it a try next time the wind is around 20 knots.

Cheers

Numb Thumbs

#4 Jurgen Heilig Jun 05, 2005 03:57 AM

Quote:

Originally Posted by flieslikeabeagl
Let's get this Part II thread rolling:

Has anyone tried the Micro Jet as a slope soarer? With the good aerodynamics of the airframe, and a low AUW (no heavy motor or large battery pack to carry) I would think it would perform well. The tough Elapor foam would be icing on the cake.

-Flieslikeabeagle

I hate to disagree, but the MJ having good aerodynamics? You must be kidding. ;)

The Twin-Jet would be much more suitable for the slope.

:) Jürgen

#5 I Crash Often Jun 05, 2005 07:57 AM

I was just wanting to give the specs from mine.
I have a Himax 2815-2000, PHX-25, TP-2100, HS-55's and a APC 6x4.
It rolls off to the left pretty good but you have time to catch it.
It RIPS too!! I use full rates and when it is rocketing up and I give it full right stick, it spins around 400-500 rpm.
Also it is so cool to come out of a power dive and go over your head at 100mph.
It sounds just like a F1 race car.
One last thing it does is climbs straight up just as fast as it does level.
Well enough blabing, you guys already know how cool this plane is.

#6 flieslikeabeagle Jun 05, 2005 01:17 PM

Jurgen, disagreement is the spice of life, so by all means, disagree, especially if I might learn something from it!

What bad aerodynamic characteristic does the MJ have? I know it likes to torque roll left under power, and stall the air over the top of the LE if too much up elevator is applied, but the first problem will go away with no motor torque, and the second should go away as the wing loading of a slope version will be a lot lower??

I have no doubt the Twin-Jet would be more fun (bigger and easier to see, for one), but the MJ was on sale recently for $34... that's a whole lot less $$$ than the Twin-Jet, hence my interest. :)

-Flieslikeabeagle

#7 Jurgen Heilig Jun 05, 2005 01:44 PM

Quote:

Originally Posted by flieslikeabeagl
Jurgen, disagreement is the spice of life, so by all means, disagree, especially if I might learn something from it!

What bad aerodynamic characteristic does the MJ have? I know it likes to torque roll left under power, and stall the air over the top of the LE if too much up elevator is applied, but the first problem will go away with no motor torque, and the second should go away as the wing loading of a slope version will be a lot lower??
...

-Flieslikeabeagle

You were asking about the suitability of the Micro-Jet as a slope soarer. I am sure if you have a look at some PSS (Power Slope Soarers) models, you will see what it takes for good performance (Hint: high aspect wing ratio, glider wing section, etc. ;)).

:) Jürgen

#8 iceman3 Jun 05, 2005 02:03 PM

Hi all

I just wondered if anyone have tried an outrunner on the MJ? I have got a 300df motor that I have planned to use, but I am unsure about how to mount it properly. Anyone got a suggestion? If I can get this to fit, my MJ will weigh only about 250-260 grams, and that will give much easier handling/launching and maybe characteristics in the air, especially when I get 390 grams of thrust and a pitchspeed of about 70mph according to the test tables I have read.

#9 flieslikeabeagle Jun 05, 2005 04:21 PM

Hmm. I have no doubt that for high performance sloping something along those lines is the way to go, but I see folks around here sloping EPP flying wings routinely, and they have moderate wing aspect ratios and often dubious airfoils. I have also sloped a $5 foam chuck glider converted to 2-channel RC and had lots of fun with it ... it has little penetration, but it soars, and that is enough for me!

Do you not think the MJ would be better than my $5 foam toy glider? Is the delta planform that much draggier than those cheap EPP flying wings?

-Flieslikeabeagle

#10 flieslikeabeagle Jun 05, 2005 04:25 PM

iceman - how big a prop does that 300 DF want to swing? If it's bigger than the stock direct-drive inrunner setups, that "torque roll of death on launch" that the MJ is famous for will get worse...

One of my flying buddies is using the Skatty 400XT on an EPP flying wing. I believe it's manufactured by the same company as your 300DF, but is slightly larger and much lower Kv. He mounts it to a short piece of aluminum right-angle bracket, which in turn is glued down to the wing.

I believe the 300 DF is smaller in diameter than the stock Speed 400, so it should fit in the MJ, you just need to make up some sort of mount for it.

-Flieslikeabeagle

#11 Butch777 Jun 05, 2005 11:11 PM

MY microjet weighs 10oz flying. I fly it in the foothills and have brought it in for a landing several times when it just flew right by, power off and soared along the ridge. On one windy day, it took 6 attemps to land to get it in, it just wouldn't come down. But, I changed my airfoil to semi-semmeterical, that may have helped. Butch

#12 erashby Jun 06, 2005 12:28 AM

Quote:

Originally Posted by Butch777
But, I changed my airfoil to semi-symmetrical, that may have helped. Butch

How did you make it semi-symmetrical? Did you shave off or sand down the bottom?

#13 flieslikeabeagle Jun 06, 2005 02:29 AM

That's just what I was going to ask!

-Flieslikeabeagle

#14 iceman3 Jun 06, 2005 09:44 AM

flieslikeabagl

I have plans on using a 5x4.3 or maybe a camspeed 4.7x4.7. What do you think about that?

#15 kdk Jun 06, 2005 11:16 AM

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.


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