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Old Aug 13, 2003, 08:03 PM
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erashby's Avatar
Utah
Joined Aug 2001
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Microjet owners??Questions???

Tell me what motor, battery pack and prop you are using?
What is the amp draw or WOT flight duration? RPM?

What modifications have you made?

What is your Microjet's all up weight?
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Old Aug 14, 2003, 06:15 AM
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JVBAV8's Avatar
Honolulu Intl, Hawaii, United States
Joined Jun 2003
472 Posts
you've seen my stock setup
3s1p stock s 400 12.2 oz stock 5" prop

my new setup is
mega 16/15/4
6x5 aeronaut carbon prop
3s2p etec 1200s , more for cg and duration
15.4 oz still under box stock weight
can't give you a flight time or current draw
1/2 throttle and it pushes up my hand >1:1 thrust
full throttle is scary, seems as if if might get away
this is static thrust so at speed when the prop unloads
there should be even more thrust

just gotta know where the ground is
when you're diving with the power on
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Old Aug 14, 2003, 09:09 AM
"Bible Thumper"
AMTJIM's Avatar
United States, AZ, Tucson
Joined Mar 2001
1,924 Posts
Mine is 7 cell 600AE and the spd 400 it cam with. 2 HS-55 servos a GWS RX and a 20 amp GP ESC. Flies at 14.1 oz. I use a 5x4 APC E prop. Maybe going to try a 4.8 V spd 400 and 6 cells. Should take it down to low 13 oz. Like always, with good TM, stays up a while. Add up trim, loves to dive even with a good runninh throw, then detune it once in the air. Other than power, I don't think I am going to mod anything.
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Old Aug 14, 2003, 10:42 AM
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Brad Hale's Avatar
Cape Coral Florida
Joined Apr 2003
37 Posts
This looks to me to be a great little airplane. So far, I have 2 false starts and 1 good flight (3rd flight was very impressive!) on my new micro jet....it's been raining for days..for starters am flying with stock configuration sp 400 w/ stock prop. I am not sure about trim setup though. Yes, I read the instructions and have elevator up "pre" trim for launching.

For test flights i'm using a 900 ma nmhi 6 cell pack.......leftover from my very first plane....an XL firebird (15 planes since then). First flight I had the CG right on the factory location but the nose kept dropping even with full throttel and moving to full up elevator, traveled about 75 yards then "went in" at about a 30 degree angle.....no damage! Amazing!

For second flight I moved back the CG about 1/8". It held nose up a little better but still ended up nosing in at about 15 degrees. Again...no damage!

For third flight moved CG back another 1/8" (a 1/4" total now) and had a good flight. Once I got it going, I trimmed from "full up trim" to "full down trim" and it started to fly good. But when at WOT it goes nose up even with full down elevator it keeps going up....and up. Slow speeds resulted in the porposing action.

I guess here is my question. Should I be exactly "dead on" with the factory CG and how much up elevator should be set for launch and what position is it in for regular flight? Also, should I revert to the launching trim position for landing. Thanks in advance for your input.
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Old Aug 14, 2003, 11:52 AM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
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It's all there: http://www.rcgroups.com/forums/showt...from+multiplex

Current set-up: Hacker B20-18L, 7x KAN950, future-9e, CAM prop 4.7x4.7", weight: 387g. 16.800 rpm at 11A (static), about 10A during flight continuous full throttle.

Jürgen
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Old Aug 14, 2003, 12:09 PM
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Brad Hale's Avatar
Cape Coral Florida
Joined Apr 2003
37 Posts
Just found this discussion thread on Micro Jet Launching....No need to respond to my questions here...I am at this thread
http://www.rcgroups.com/forums/showt...hreadid=120022
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Old Aug 14, 2003, 04:43 PM
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Brad Hale's Avatar
Cape Coral Florida
Joined Apr 2003
37 Posts
Thanks for the link. It has the awnsers I a looking for.
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Old Sep 05, 2003, 02:54 AM
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erashby's Avatar
Utah
Joined Aug 2001
1,938 Posts
MJ ready for Maiden flight tomorrow

I finished my MJ and wanted to get any advice befoe the maiden flight tomorrow. I added a small carbon fiber rod to the fuselage. I reinforced the motor mount with carbon fiber tape, and I used magnets to make the fins and turtle deck removeable. There are four sets of magnets adding 13 grams of weight (Edited: I thought that it was an ounce of weight, but I was wrong). In retrospect I may remove the magnets and just use velcrow to save some weight.

Below are some pictures. My AUW is 10.4 oz (295gm). That is with a Razor 300 direct drive and a 4.7 x 2.3 Graupner cam folder, CC Phoenix 10 ESC, and 2S1P 1200 e-tech lipo batteries. At 7 amps I get 6.2 oz of static thrust. At WOT I get 9.3 amps at 7.1 oz of static thrust.

I will also test fly it with a 3S1P 1200 e-tech pack. My AUW goes to 11.2 oz. I get 8 oz of static thrust at 7 amps. And at WOT I get 11oz of static thrust at 14 amps. 14 Amps is more than the razor or the e-techs can handle.

If I go with a Mega 16/15/5T and a 5x5 spoon carbon zagi prop, then my AUW is 12.8oz with 2S1P: 13.6 with 3S1P, and 17.4 oz with 8cell kan 950 pack.

I get 10.8 oz of thrust at 7 amps for both the Kan 8 pack and the 3S1P e-tech. The 2S1P e-tech pack gives 6.5 oz at 4.6 amps.

So the question is which setup?
1) Razor 300 on 2S1P or 3S1P e-techs? (8oz thrust at 7 amps with AUW 11.2 oz for 3S1P)
or
2) Mega 5T on 3S1P e-techs? (greater thrust10.8 oz at 7 amps , but greater AUW13.6oz)
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Last edited by erashby; Sep 05, 2003 at 01:34 PM.
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Old Sep 05, 2003, 02:57 AM
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erashby's Avatar
Utah
Joined Aug 2001
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more picts

Magnetic fins
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Old Sep 05, 2003, 02:57 AM
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erashby's Avatar
Utah
Joined Aug 2001
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More Picts

Magnetic turtle deck.
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Old Sep 05, 2003, 03:32 AM
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JVBAV8's Avatar
Honolulu Intl, Hawaii, United States
Joined Jun 2003
472 Posts
gotta say the thrust to weight ratio of the razor
and 3s1p etec 1200 is higher than the mega with 3s1p 1200

power off performance such as glide speed and
reserve AOA(stall resistance) will be improved with the lighter weight

climb performance and top speed are not always accomplished
by adding thrust if the weight increases

don't worry about wot performance for extended times
you probably won't be flying full throttle the whole time
do worry about the current draw and the etec 1p limit
14a > 10c(12.00a)
if you don't punch full for extended periods it should be OK
I have ran 3s1p but usually run 3s2p
also I have a higher current draw that can be 24a with the 5.6x6
vario prop and mega 16/15/4

paint your canopy!
can use testors paint pens or magic marker
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Old Sep 05, 2003, 05:58 AM
Hmm, kerosene... :)
NightSwan's Avatar
Weert(LB) - the Netherlands
Joined May 2002
953 Posts
I flew mine on a mega16/15/3 on eight cells..
Wow.. fast!
Not an easy plane on that setup though...

Hans
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Old Sep 05, 2003, 08:12 AM
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erashby's Avatar
Utah
Joined Aug 2001
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Thanks for the comments. I will "dress" her up a bit. Paint cannopy, and add stickers, mostly to help with orientation. I could go with 3S2P and an AU of 13.8. That would allow WOT at 14 amps, but the razor doesn't like more than about 10 amps, I've been told.
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Old Sep 05, 2003, 08:50 AM
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Peter D Rieden's Avatar
Surrey, UK
Joined Mar 2003
388 Posts
Erashby said:
<I used magnets to make the fins and turtle deck removeable. There are four sets of magnets adding 13 grams of weight (Edited: I thought that it was an ounce of weight, but I was wrong). In retrospect I may remove the magnets and just use velcrow to save some weight. >

Can't comment on the fins (lots of people have used bolts, rawlplugs etc to make the fins removable) although I feel that loss of a fin in flight could be a "learning experience"!

However, I'd strongly recommend gluing the turtle deck on as directed in the instructions. The whole wing becomes MUCH stiffer once the deck is glued on and you may find that the structural performace of the magnetic deck isn't quite enough...

Peter D Rieden
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Old Sep 05, 2003, 09:26 AM
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Bill Glover's Avatar
United Kingdom, Bracknell
Joined Nov 2000
11,794 Posts
Re: Microjet owners??Questions???

Quote:
Originally posted by erashby
Tell me what motor, battery pack and prop you are using?
What is the amp draw or WOT flight duration? RPM?

What modifications have you made?

What is your Microjet's all up weight?

Kontronik Fun 400-28, 8x1700 AUP nimh, CAM 4.7x4.7.

Static 20A and 22,500 rpm. Flight timer set for 8 mins, typically land around 8:30 to 9:00 and have never hit LVC.

Mods: extended tray to move motor back (for correct CG), mylar hinged elevons, replaced elevon horns & linkages, sandpaper 'grips' for easier launching, ultra-brite LED in nose.

AUW 22.4 oz / 635 g.

Ballistic

All in here (plus details of other setups):

http://www.rcgroups.com/forums/showt...hreadid=107953
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