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Old Aug 27, 2012, 08:16 AM
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Kurt's Avatar
United States, TX, Houston
Joined Sep 2003
1,931 Posts
Quote:
Originally Posted by medroller View Post
I've been flying my rad with the 2826/6 motor on 4cells and real happy with the speed, but one of my servos crapped itself on the weekend and she went in nose first. But I have one sitting in the shed waiting for the turnigy2836 motor, which has just arrived.
Bummer on the servo - about how many flights did you have on her?
What size prop are you running with the 2826?
I really need to get a watt-meter.... the 5x5 probably is too small even with 3S?

2826 ratings are 342W, 34A.

Quote:
Originally Posted by medroller View Post
Hey Kurt, I was running the same motor as you are. I noticed on 4s, the motor would start to break down when it got to hot. In the foam on top of the motor, I cut a hole and glued a tiny scoop.
Thanks Med - we're thinking the same way. Flew her the other night on 3S, with the last ~1/2" of foam engine nacelle cut away and the motor was barely warm. A little scoop is in the plans, unfortunately with the solid motor mount the air intake really has to be just behind the mount so air can only go through the motor through the holes in the stator part.
Can you post a pic of your scoop pls?

Yes I use Orange 6-ch with satellite in all my planes, so far no issues whatsoever! (knock on wood...)
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Old Aug 27, 2012, 12:27 PM
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mrmurder1975's Avatar
Joined Dec 2007
624 Posts
maidened the radjet yesterday.

should of stayed at home!
gave it a chuck and it rolled left straight into the ground.the pointy nose is no longer so pointy.
gave it another chuck,harder and with more throttle. again it rolled left but this time leaving a nice big split down in the foam under the cockpit and almost snapping off one of the torpedo shaped things on the end of the wing (dont know what they are called)

its running a 2200kv motor,as the stock one that came with it was dud straight out of the box (typical or what). also a plush 40a,1300 3s lipo and a 6x4 prop. others are using the same set up so i dont know why its not working for me. seems to be suffering the same problems as my (mikeys rc version) scratch f117, the dreaded torque roll.
i solved that with the scratch by moving the battery further out over the right wing (viewed behind) and using about a 1/4 throttle on launch with a medium power under arm throw. (flys well now!)

not sure how i will do the same with the jet. the battery/fuse area is barely wider than the battery,as you all know. although i do currently have the battery mounted on the left hand side of the airframe so maybe moving it over to the right will shift the lateral cg enough to stop the roll. i have already balanced the lateral cg though,took a penny taped under the wing to balance it.

i think on the next throw i will give it about the same amount of throttle as it takes the f117 to launch but a bit of a harder throw as the radjet seems to like quite a lot of power to get going.
also the recommended cg is c*ap! way too nose heavy. many people are saying 400mm from the nose is optimal. i have mine about 390mm (ish), i didnt go back as far as 400 as i didnt want to weaken the airframe by carving out more foam but in hindsight i think i will follow the masses and go to 400 as when it was torque rolling,it was going nose down at the same time. maybe that extra 10mm or so along with the other measures will get this bloody thing to fly.

after all the hassle of getting it to my door,and the dud motor, i thought it would be too much to ask for it fly on the first throw. seems i was right!

**i have just carved out more foam and now have my cg at the 400 mark. hopefully along with moving the battery over to the other side my next launch will be successful.**

if anyone has any tips on how i can solve the torque roll,or any tips in general,im all ears!
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Old Aug 27, 2012, 01:04 PM
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setxws6's Avatar
USA, TX, Lumberton
Joined Oct 2005
383 Posts
Wow sorry to hear you had a bad first impression.

I mounted my 3s 1300mah flat down the middle of the jet, not on one side or the other. It fits were it will squeeze in between the walls of the jet, behind the canopy. I did have to carve out some foam. I can take a picture of it if it would help.

I've found that the CG is really good anywhere between the front square wing mount tabs all the way to just in front of the finger grip on the underbelly.

I do however have a 3000kv motor with a 4.7x4.2 apc prop, so I really don't have any torque roll on throttle up ever. But I do launch with about half throttle and at a 45 degree angle. I grab it using the finger tab on the underbelly to launch it. I have a funjet ultra with a 2200kv 4s 3300mah lipo and 7x5 apc sport prop, and it torque rolles hard, but I still don't have any problems launch it. Just toss it with a upward angle with half power. It will roll on it's side, but I quickly recover it with no problems.
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Old Aug 27, 2012, 05:59 PM
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mrmurder1975's Avatar
Joined Dec 2007
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Quote:
Originally Posted by setxws6 View Post
Wow sorry to hear you had a bad first impression.

I mounted my 3s 1300mah flat down the middle of the jet, not on one side or the other. It fits were it will squeeze in between the walls of the jet, behind the canopy. I did have to carve out some foam. I can take a picture of it if it would help.

I've found that the CG is really good anywhere between the front square wing mount tabs all the way to just in front of the finger grip on the underbelly.

I do however have a 3000kv motor with a 4.7x4.2 apc prop, so I really don't have any torque roll on throttle up ever. But I do launch with about half throttle and at a 45 degree angle. I grab it using the finger tab on the underbelly to launch it. I have a funjet ultra with a 2200kv 4s 3300mah lipo and 7x5 apc sport prop, and it torque rolles hard, but I still don't have any problems launch it. Just toss it with a upward angle with half power. It will roll on it's side, but I quickly recover it with no problems.

yes please,i would be interested in seeing a pic or 2 of how you have yours set up.
do you think i would be better off with a smaller prop? the only thing i have smaller is a 5x5e or the stock prop that came with it.
maybe i should go down to a 4.7x4.2 like you? i mean if you can run that prop on a 3000kv with no problems,then it might be the way to go for me too....
anyway,thanks for the info. just waiting for some decent weather (not easy to come by in summer in the uk) to go give it another try!
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Old Aug 27, 2012, 08:25 PM
ZX-10R pilot
setxws6's Avatar
USA, TX, Lumberton
Joined Oct 2005
383 Posts
Okay here's some pics of my dirty old bird. I use a 3s 1300mah 40C skylipo, Futaba Fasst 7ch reciever, Dons wicked 3000kv outrunner (little bigger and heavier than stock), Proton 40A esc, APC 4.7x4.2

The prop you're using sounds to be right for that much KV, unless you went to a 4s 1000-1300mah lipo, then you'd have to prop down to something like a 5x5 maybe. It all depends on what the motors rated for and what watts and amps looks like with each prop. I thought I was getting Dons wicked 2700kv motor and was going to use an APC 5x5 prop, but by accident got the 3000kv. But with a change of prop to 4.7x4.2, I'm getting similar performance.
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Old Aug 27, 2012, 10:00 PM
Pony Express
United States, IL, Cary
Joined Jul 2011
16 Posts
I have my Nanotech 1300 3S way back as well. Flies so much better that way. Like so many others, I cut lots of foam out of the fuse and also carefully cut hatch tops off and reattached with magnets. So much easier to get at ESC and battery.

Quote:
Originally Posted by Dillzio View Post
That's great Colin, but just what does that have to do with the radjet?

I've decided to (try to) set my jet up with a CG 393mm back from the nose tip, which seems to be what many recommend. I tried putting thumb tacks at this point to balance my finger on, but found that wasn't accurate enough so I ended up using my coat hanger CG rig (see attached pics)

For me to achieve the CG I wanted with a 3S battery 1300mah nanotech I need the battery pushed so far back that it touches the ESC. The battery is so far back that the only way to get it out is by pulling on the wires.

Radjet fliers, is that seriously how far back all of you keep your batteries? Doesn't that make it hard to get the battery out?

Also, how on earth do people like Rattlesnake fly with 1000mah 6s packs? Rattlesnake, i noticed you can remove your whole top deck, is that so you can mount your battery closer to the middle of the airframe and still have access to it?
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Old Aug 28, 2012, 12:49 AM
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Australia, QLD, Townsville
Joined Jul 2011
229 Posts
heres some pics of the tiny scoop , It's just an angle cut from a ec3 connector.


The aftermath


And the bigger powerplant 2350kv for the next rad
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Old Aug 28, 2012, 07:47 AM
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Owatonna MN 55060
Joined Sep 2005
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Launch Tips

Quote:
Originally Posted by mrmurder1975 View Post
if anyone has any tips on how i can solve the torque roll,or any tips in general,im all ears!
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Put some extra up trim on a switch (I use normal flap position on my DX - 7)

Mix rudder to aileron so you can turn it with the left stick (10% each way works for me)

Throw it full throttle
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Old Aug 28, 2012, 04:00 PM
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THESANDMAN's Avatar
United States, NY, New York
Joined Oct 2010
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toss it at an angle opposite of the torque roll. it will lvel out to the point where you can control it .
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Old Aug 28, 2012, 09:11 PM
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Australia, QLD, Townsville
Joined Jul 2011
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Quote:
Originally Posted by THESANDMAN View Post
toss it at an angle opposite of the torque roll. it will lvel out to the point where you can control it .
Yep ,that's the way.

Went out to test the 2836 motor today. I was trying different props with 3 and 4 cells everything was going good , UNTIL!! ,On the last flight I chucked in my new 1300 nano 45c. It was very nose heavy, but with a good throw and punching the power in , she took to the air. after 2 WOT runs the motor stopped. I thought she was gone ,but I had height and got her back with no damage. I had a 5by5 prop on s and I reckon I was pulling around the 800watt and high 50's amps. The motor got so hot that the foam bubbled at least an inch or so back up the fuse.
I have a 2200kv ntm prop drive, so I'll throw that in and see what happens.

I take full responsibility, but maybe those nano's really Do let the juices flow.

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Last edited by medroller; Aug 28, 2012 at 09:27 PM.
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Old Aug 28, 2012, 09:19 PM
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THESANDMAN's Avatar
United States, NY, New York
Joined Oct 2010
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Quote:
Originally Posted by medroller View Post
Yep ,that's the way.

Went out to test the 2836 motor today. I was trying different props with 3 and 4 cells everything was going good , UNTIL!! ,On the last flight I chucked in my new 1300 nano 45c. It was very nose heavy, but with a good throw and punching the power in , she took to the air. after 2 WOT runs the motor stopped. I thought she was gone ,but I had height and got her back with no damage. I had a 5by5 prop on s and I reckon I was pulling around the 800watt and high 50's amps. The motor got so hot that the foam bubbled at least an inch or so back up the fuse.
I have a 2200kv ntm prop drive, so I'll throw that in and see what happens.

I take full responsibility, but maybe those nano's really Do let the juices flow.
those 2836 motors have a short life span your lucky to get 20 flights with a 4s with a 3 cell they will ast but anything higher . they just burn up . i went through three of those motors ,and decided on getting an edf motor that was capable of both 3s and 4s it was recomended by someone here on rc groups. ive gotten over 20 flights without a hitch.and the speed is compatable to the 2836 i just upgraded to a het2w30 motor . but i havent installed it in my flyjet yet. so as of right now im happy with the motor im running im getting a top speed of around 115 on my flyjet x83 on this radjet it will easly do 120 with a four cell
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Old Aug 29, 2012, 12:28 AM
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Australia, QLD, Townsville
Joined Jul 2011
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Quote:
Originally Posted by THESANDMAN View Post
those 2836 motors have a short life span your lucky to get 20 flights with a 4s with a 3 cell they will ast but anything higher . they just burn up . i went through three of those motors ,and decided on getting an edf motor that was capable of both 3s and 4s it was recomended by someone here on rc groups. ive gotten over 20 flights without a hitch.and the speed is compatable to the 2836 i just upgraded to a het2w30 motor . but i havent installed it in my flyjet yet. so as of right now im happy with the motor im running im getting a top speed of around 115 on my flyjet x83 on this radjet it will easly do 120 with a four cell
I just ordered another 2836, ( bugger). The 2836 2200kv ntm that I was going to put in ,has the same bolt pattern ,but the wires come out the side, I'll see if I can mod the end bell. So for the time being, I'm putting the 2826 back in. she does handle short burts of 4s .

Even though we get good info off these sites, it's still a learning curve.
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Old Aug 29, 2012, 07:04 AM
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Joined Dec 2007
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thanks for the tips gents. however, before i saw all this i went out yesterday for another crack at it.....

can you guess how it ended?!?

same as before!! only this time i managed to very nearly snap it in half!
its fixed again now but my radjet is quickly becoming more hot glue than foam!
good idea about throwing it at an angle opposite to the torque roll,why didn't i think of that. i will also dial in a bit rudder to aileron (thanks gohmer) and between the two,hopefully that will bring me some success.
i am a little concerned about throwing it at full throttle,i currently throw it (hard) at half and its got a hell of a lot of thrust at half throttle,almost too much to hang onto with those little finger holds. i have visions of it getting out of control and raking the back of my hand at full pelt! anyone else throw theirs with a 2200 kv and a 6x4 at full throttle? seems a bit dangerous!!
maybe i should just man up and try it!

anyway,thanks for the input gents and as soon as the British summertime weather permits,i will be back at the field for another attempt!
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Old Aug 29, 2012, 08:18 AM
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Paramanic's Avatar
United Kingdom, Scotland, Motherwell
Joined Dec 2011
209 Posts
has anyone done a rudder mod to this plane?
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Old Aug 29, 2012, 09:49 AM
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Owatonna MN 55060
Joined Sep 2005
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Quote:
Originally Posted by mrmurder1975 View Post
thanks for the tips gents. however, before i saw all this i went out yesterday for another crack at it.....

can you guess how it ended?!?

same as before!! only this time i managed to very nearly snap it in half!
its fixed again now but my radjet is quickly becoming more hot glue than foam!
good idea about throwing it at an angle opposite to the torque roll,why didn't i think of that. i will also dial in a bit rudder to aileron (thanks gohmer) and between the two,hopefully that will bring me some success.
i am a little concerned about throwing it at full throttle,i currently throw it (hard) at half and its got a hell of a lot of thrust at half throttle,almost too much to hang onto with those little finger holds. i have visions of it getting out of control and raking the back of my hand at full pelt! anyone else throw theirs with a 2200 kv and a 6x4 at full throttle? seems a bit dangerous!!
maybe i should just man up and try it!

anyway,thanks for the input gents and as soon as the British summertime weather permits,i will be back at the field for another attempt!
Try some sandpaper glued in the finger grip notches. I always throw mine full throttle. One has a 2900 KV motor with a 6X4 prop. Also try the up trim on a switch.
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