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Old Mar 30, 2011, 07:39 AM
michigan jet guy
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mirage 2000

okay before i build one of cad designed f-84g's i want to build something from someonelses plans first. Ifound these plans online i forgot where but figurered it is a delta wing which i hear is easy to fly, I wouldn't know never fly one. Now i know i need 4.75 sq in for a 70 mm fan and scaled these plans accordingly. I plan on using a change sun 70 mm fan as the price is rifgt and not after crazy numbers or really high performance. I don't know what motor maybe someone can suggest one. I laid the top view of the ducts i plan to make on the plan can someone tell me if these look right. I'm a newcomer to the edf scene. I've done a few pushers and i like them, But i need to do edf to get my jet fix if you will. I plan on building as light as possible and fiberglassing this and if it works out ok maybe doing some detailing. So what do you think. Will this be a good first edf if you will? Phil
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Old Mar 30, 2011, 09:52 AM
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Those are plans for the Phillip Noel Mirage. They were in the first issue of RC Jet International back in like 1994. You may be able to order a kit off of his website. It used the RK 720 fan unit.

For edf, a good rule of thumb is move the fan further toward the back of the airplane when converting from a glow fan. You'll have to balance the weight of the battery in the nose forward of the intakes. I'd move the fan back at least one bulkhead if not two. Moving the fan back also lets you keep the inlets seperated for a longer time before they join (if you redraw the openings) and that creates more room between the inlets so that you can slide the batteries further toward the back to avoid being too nose heavy. I've seen it happen where the fan was too far forward and the battery size/weight was restricted and thus flights were shorter...it happened to me early on!

For the inlet ducting, I'd use heavy cardstock for the curved parts, or cereal box cardboard, or donut box material. Wet it with water and it's a lot easier to work with. The inner inlet wall can be made from regular balsa sheet or thin 3mm depron.
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Old Mar 30, 2011, 03:41 PM
ANDY su27/andy c
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Philp Noel also designed a smaller version which is suitable for WMT480. or in my case I installed the WMT 609 fan on 6s Mega22/20/3 1000w @40amp
AUW 40oz.
I dont know if this plan is still available check with TRAPLET.

Andy C
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Old Mar 30, 2011, 11:02 PM
michigan jet guy
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ok thanks for the info on fan placement that will come in handy. I was planning on doing fiberglass ducts i want to try that. Last question for now do deltas fly easier? Phil
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Old Mar 31, 2011, 07:01 AM
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Cool! I recently designed and built a 55mm EDF mirage, however, it is a box fuse. I have a thread in this forum as well. IMHO, I think this type of delta is more of a challenge to fly than a traditional wing/stab setup. The plane is extremely sensitive to CG, and highly maneuverable -- she will turn and change direction on a dime. Very fast and squirly. Nice slow speed/high alpha performance, and i have yet to stall her. It took me a few flights to get the CG and control throws down, and now she is a bit more calm, but the plane definitely requires constant attention in the air. In comparison, I also built a 64mm L-39 that practically flies itelf.
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Old Mar 31, 2011, 07:21 AM
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In the early days of the EDF era when we flew with heavy NiCd cells was not a bad thought to place the engine further back. But now with the much lighter lipo's I would be careful with this.
My first Mirage had the engine at the back batterie was 14x 2000sanyo subc cells. That was in2000

The fan is placed where you can see the brown tape.
The second was 4s 3700mAh lipo with the same engine. Five years ago
See the difference


The third is a lot smaller but here also is the engine placed more in front. Last week
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Last edited by Von W; Mar 31, 2011 at 07:23 AM. Reason: iets vergeten
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Old Mar 31, 2011, 07:23 AM
michigan jet guy
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hmm maybe i should wait on this one then as my flying skills are not quite up to that yet. On the other hand i could build it and have to look foward to as my flying skills increase. Phil
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Old Mar 31, 2011, 07:26 AM
michigan jet guy
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well i suppose maybe then i should keep the fan in the location located on the plans or move it foward just a tad seeing how i wont be using ni cads. I also plan on using electric retracts. Don't know how much the nose gear would affect the balance. Phil
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Old Mar 31, 2011, 07:33 AM
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I like deltas cause you can fly them very slowly at high angle of attack if you have enough power, and they fly no more difficult than other models but they are much more sensitive to their CG.
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Old Mar 31, 2011, 07:41 AM
michigan jet guy
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so i should be able to handle this with intermediate flying skills asm long as it is balanced right. Cooll. I'm goona start on this after i finish my cessna 150. Any recommendations for a fant unit and such? Was wanting to the change sun 70mm with 4 or 5s lipos. Phil
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Old Mar 31, 2011, 11:04 AM
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The battery weight I fly with today is about the same as with nicads, I just have enough capacity to fly for 5 minutes or so. Batteries may be a little lighter than back then, but not half, unless you chose to fly smaller cells. What I've seen happen many times is people pulling a lot of amps and too small packs and they get low voltage cutoff and/or they puff packs. If you run lighter packs and this happens and you want to go with larger packs to support the amp draw, you may end up being too nose heavy because you can't slide the packs farther back. So, you end up with dead weight in the form of ballast in the tail to compensate for heavier packs, or you have to buy a different motor that pulls less amps. If you move the fan back and thus create more room between the inlet ducting, you can run the heavier packs and slide them back far enough to balance the jet without dead weight in the back. If you run lighter packs to keep the weight down (usually that's a mistake but it depends on the situation), you can slide the packs forward to achieve the proper cg.
Not that I didn't say move the fan all the way back to the tail, I said move it back one bulkhead.
Admittedly, I haven't built a Mirage so I'm not fully familiar with them, but over the last 12 years I've been designing and flying edf models, I've got a feel for where the fan should go, especially after placing it too far forward a few times. My Wattage F-22 edf conversion was one example, I had to rebuild it after a crash and I moved the fan back, and lost the 4 oz of ballast in the tail.
Good luck!
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Old Mar 31, 2011, 11:43 AM
michigan jet guy
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alright i'm going to move it back oe bulkhed as that explanation makes a lot of sense. will the long inkes caus eproblems or will they be ok? this will be my first edf jet so fire away with the suggestions and ideas. Thanks ed. Phil
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Old Mar 31, 2011, 11:58 AM
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I've often wondered how others figured out fan placement. For my mirage, I thought the fan would be more towards the center of the plane. Luckily, I built the airframe first, did some test gliding, and referenced other mirage models to get the proper CG. Then I began placing equipment according to the CG. In order to get my model to balance properly, I had to install the fan as far aft as possible -- allowing me to use 1300 - 2200mah 3S 30C batteries. Is there a better method of doing this?
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Old Mar 31, 2011, 12:35 PM
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I agree that it depends on the model where you put the motor. And many of the foam jets have indeed much too small battery packs for a proper flight time. Thats wy when I design a model I always maximize the battery pack. At the Mirage, I was wrong it had 12 sanyo subc 2000mAh cells instead of 14 cells. that came on around 720gr and now with the lipo's It's about 450g for the cells, indeed not half the weight but significant lighter and I've got more capacity on board with about the same voltage and so i've got a longer flight time and none of the models had dead weight on board.
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Old Apr 06, 2011, 07:42 AM
Aka: Tom Jenkins
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Palm Beach County, Fl.
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Maybe just get a fly fly from HK and figure what you'd like to do on a scratch build next time. You'll be in the air without breathing all the dust.
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