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Old Mar 13, 2008, 09:33 PM
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Canberra, Australia
Joined Jan 2003
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Mirage 2000 Gurnli or Kamdex Help needed

Has anyone else had experience with this model (possibly sold by a different supplier).
My example needs more power or better air flow
The motor is an outrunner 2826 (purple) and the battery was a 1500mAh Lipo.
Can anyone tell me what rpm/v the stock outrunner is ?
The model needs a better motor and I have another 4200 rpm/v outrunner that should fit if the fan is suitable

Any tips to improve flight.
Possible ideas are a shaped exhaust
New motor/battery
Bigger cheater holes. Currently the reciever is partially blocking one of them.
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Old Mar 14, 2008, 01:16 AM
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EDFjet's Avatar
Albury, Australia
Joined Feb 2008
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Higher Rating lipo will help. What is the discharge rating on the current lipo?

Also, what size fan are you running

Liam
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Old Mar 14, 2008, 01:49 AM
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I have already placed an order for a better LiPo as the one in it was only a 1500mAh and was unmarked but I guess a 15C. It was hot after the flight which must be a bad sign.
The new one will be a 2200MaH.
I have not touched the fan but it says it is a 70mm unit.
Is it best to have cheater holes on the top or bottom ?
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Old Mar 14, 2008, 01:57 AM
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Albury, Australia
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If you are going to use cheater holes, better for it to be on the bottom.

If the new lipo is 25/30c you will notice and increase in thrust. Have an idea of the area of the intakes?

If you are thinking about a new motor. A HET 2W in a Wemotec WM480 or HET 6904 fan should give you a good amount of thrust.
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Old Mar 24, 2008, 03:14 AM
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Australia, QLD, Mooloolaba
Joined Aug 2007
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Hello Col, only other point to consider here is the weight of the model. I have the Kamdax version, and it doesn't like any extra weight.

AUW of the Kamdax jet including 1800 mah 20c lipo = 550 grams.

I have ditched the stock fan and replaced with a Wemotec minifan. I tried running a high rpm/kv outrunner, but was seriously laking in watts. I have since replaced with a 3800 kv inrunner, producing about 300w.

The cheaters holes are on either side of the fuse, in front of the fan to help improve airflow, which is a problem for the Kamdax jet.

Hope this helps
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Old Mar 24, 2008, 07:11 PM
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Canberra, Australia
Joined Jan 2003
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Do you know what make/model the inrunner motor you used is ?
Have you any pictures of your model after the addition of extra cheater holes that you could post. My model came with two cheater holes already on either side of the fuselage but one was partially blocked by the reciever

What was performance like afterwards. Mine currently will barely climb. My best flight was from a hill with a light wind giving ridge lift which meant that staying up was not a problem, allowing me to try rolls etc.
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Old Mar 24, 2008, 10:10 PM
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Quote:
Originally Posted by Burdo
Hello Col, only other point to consider here is the weight of the model. I have the Kamdax version, and it doesn't like any extra weight.

AUW of the Kamdax jet including 1800 mah 20c lipo = 550 grams.

I have ditched the stock fan and replaced with a Wemotec minifan. I tried running a high rpm/kv outrunner, but was seriously laking in watts. I have since replaced with a 3800 kv inrunner, producing about 300w.

The cheaters holes are on either side of the fuse, in front of the fan to help improve airflow, which is a problem for the Kamdax jet.

Hope this helps
I don't have this model, so forgive my intrusion, but it looks like a knockoff of the Kamdax M2000, which I have flown a bunch.
Those two holes are not actually cheater holes. What they are is holes that were there for plastic mounts for the Kamdax glow powered fan. It kind of shows how sometimes someone can copy something without really understanding it. The Kamdax required cheater holes for really good flight, would not be surprised if a copy did, too, and I don't know if those holes for the motor mounts will cut it.
On the original one, what worked best was a hole on the bottom in front of the fan.
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Old Mar 27, 2008, 07:34 PM
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raleigh, NC usa
Joined Aug 2001
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m2000

I do not know if you built it or bought it built but there are a lot of options on smoothing the air path to the fan unit and proper placement of the cheater holes in the forums. It is well worth a search on how to do this properly before you start cutting. Ive found that no matter how careful you are - holes weaken the fuselage

The ability to squeeze a new fan in there after it is built is pretty remote without serious work and added weight.

I am assuming that the fan is from Kamdax . . if so, a common fault ive seen in many was rough foam edges around the mount causing the entry air in front and back of the fan to be disrupted.

A large divot front and back existed in mine that needed to be carefully smoothed out. I flew mine without cheater holes and it was ok . . .I smoothed the inside extensively as well as the intakes so that there was a clear path all the way back to the unit.

I would concentrate on these things:

Loose the gear if you can, it is a huge drag on performance

get newer chemistry 3s preferably 4s Lipo batteries, I would go for a little lighter on capacity and higher C rating, consider 25-30c 1800s rather than the 2200's unless you can find a pack that is similar in weight to the 1800s with a similar c rating.

Make sure the weight of the batteries is such that it will balance out the plane . . the cg is tough to hit without adding lead and that is wasted weight.. try to balance the plane loaded without the battery using lead in the battery compartment. Weigh the lead req. to balance on the cg then match that to your shopping needs . . you may have to go to the 2200 to make it work right, if not, use the lightest/ highest C rating you can work with.

Clean up any glue joints you can reach in the ducts to make the flow undisturbed and make sure your motor wires are as tight together as possible and secured to prevent disruption of flow on the exit. Smooth the inside of the intakes to a nice rounded edge.

I have no idea who's fan unit you are using but . .. . .the original fan/motor set up that Kamdax sold in these airplanes was ok . . just ok. I hear the gas fans were better but the E powered made for good sport planes.

I would recommend a better motor with higher KV that is compatible with the fan unit.

Balance the fan and make sure there is no damage to the unit.

I had one with the original factory provided set up and was not completely happy with the stock fan.

I tried to do a fanendectomy and ended up just converting it to a pusher as it was easier and now flies much better...I went with an outrunner using a 3 blade prop and pusher set up..Kamdax has notes on how to do it on their site.

There is a lot of room for improvement in so far as looks - paint and panel lines are ok - resist the temptation to add weight as any added weight drastically effects the performance of the stock set up.

just my two cents!

Before you spend a lot of money on this airplane think carefully about other options that may provide more bang for the buck.

Don't get me wrong, this is a fun edf but is will not burn up the skies without some serious effort and cash.

If you want something faster, consider converting it to a pusher, the vertical is much better and the top end is actually better with a much lower dollars/knot!

pv
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Last edited by pval3; Mar 27, 2008 at 07:41 PM.
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Old Mar 27, 2008, 09:57 PM
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Canberra, Australia
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Thanks for your advice. My air flow is not very clean currently with wires and the speed controller obstructing the airflow. I will attempt to improve this.
My model came with an outrunner motor which I have not been able to identify but think along the lines of a Mystery 3500.
I plan to stick with a ducted fan in the long term instead of going to a pusher as it some how seems more pure to me, and a pusher seems like cheating. I might though try a temporary pusher set up as I am sure the flight performance would be better.
If I was to try a 4s battery is the fan likely to accept this or am I likely to lose a blade.
Access to the fan unit is not easy and would require cutting the foam to get it out.
I have heard that narrowing the duct after the fan will speed the air flow and can improve results. Whether this applies to this particular model I do not know.
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Old Mar 27, 2008, 10:04 PM
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Albury, Australia
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I wouldnt reccomend 4s on that motor, your amp draw will be huge, and i doubt the lifespan of the motor with that much voltage across it. What size esc are you running anyway?

Yes an eflux tube may improve performance. Normally the diameter of the exhaust is %10 of the diameter of the fan...

Have you tried flying it with the new pack?

I would be thinking you should go something in the 25c or 30c range to squeeze every last rpm from that motor.

Stick with EDF man, ull love it
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Old Mar 27, 2008, 10:35 PM
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I did not get much extra thrust with the new 2200mAh battery but flight time was longer and I expect the battery is not being abused so badly.
I guess the next step is to try putting in the 4200rpm/v motor.
I do not know what the current ESC is but I have a 30A ESC I can use.
I am flying from a small hill , and when there is a light wind the extra lift is useful.
The model rolls OK but I can not see it looping the way some of the videos show with out a lot more power.
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Old Mar 27, 2008, 10:57 PM
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Albury, Australia
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If you do plan on using a hotter wind motor, get a higher rated speedy. I doubt a 30A speedy will able to handle that. Have you connected your setup to a Watt meter to get some numbers?
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Old Mar 28, 2008, 04:52 AM
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raleigh, NC usa
Joined Aug 2001
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recs

Hey Colbourne,

My recommendations are general as to the battery/fan/motor as I am making general assumptions as to what set up you are running currently. I am assuming that you do in fact have the Kamdax stock set up too.

If you are running a "mystery" motor and it came with a 3s pack, stick with it until you either upgrade to a better motor or at least know what your amp draw is under 3s and 4s batteries.

The higher the C rating, the less abuse you are doing to your packs and the more rpm you can eek out of your current set up - think sucking a soda through a capillary tube rather than a straw the higher the C rating the bigger the tube and the less work your motor has to do to get the power out.

You will also need a bigger esc than 30A if you are going to really work this thing -the last poster was dead on - 30A isnt going to cut it under most of the hotter motor set ups as well as most 4s set ups (make sure your esc is in fact 4s capable before you even go down that road as many lower and mid level escs in this 20-30A range do not seem to be).

If you do not have the specifics for the max rpm on the fan unit, and can not get it online, you will need to seriously start thinking about changing out the unit. You can push it as far as you want but remember that eventually it is going to blow apart. Run it until it dies or just swap it out to something you know will work.
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Old Apr 19, 2008, 06:26 AM
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Burdo's Avatar
Australia, QLD, Mooloolaba
Joined Aug 2007
316 Posts
Quote:
Originally Posted by colbourne
Do you know what make/model the inrunner motor you used is ?
Have you any pictures of your model after the addition of extra cheater holes that you could post. My model came with two cheater holes already on either side of the fuselage but one was partially blocked by the reciever

What was performance like afterwards. Mine currently will barely climb. My best flight was from a hill with a light wind giving ridge lift which meant that staying up was not a problem, allowing me to try rolls etc.
The motor I'm using is an obscure motor purchased from ebay, but works just fine. Don't expect anything with unlimited climbing ability, but enough to get the thing in the air and keep it there comfortably. If you want unlimited performance try a HET 6904 fan with a Typhoon 2W motor.

Here are some pics of the model with the cheater holes. I've tried to make them look a little sexy, so there not your typical square ugly looking things. I've also cut some holes underneath as well. Again, from what I've read about these things, they need as much help with getting the airflow ticking along. The performance after the cheaters was definitely noticeable. I've already trashed two of these things using all types of set ups. (Brushed motor/stock set up/without cheaters/4900 RPM outrunner) etc..etc..
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Old Apr 27, 2008, 10:16 PM
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Canberra, Australia
Joined Jan 2003
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My current set up is now :-

One big cheater hole in bottom of the fuselage.

Rounded inlet.

Wheels removed but wire left in place to protect model on landing.

Front servo removed as now not needed.

2100mAh 20c lipo .

No extra ballast was required.


Hand launching is ok holding model at very rear and giving a good throw. I switched the model to mode 2 (throttle on left stick) as otherwise it was easy to hit the mixer switch on launching . ( Stupid radio design)

The new battery made an appreciable difference and is still cool on landing after a ten minute flight.
I would like to try a 25C or 30C when I have one available.

The model still needs more thrust but at least now I feel I can enjoy it rather than just be struggling to stay in the air. I can now do high banked turns which before resulted in great loss of speed and height.
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