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Jan 14, 2008, 02:08 AM
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Carnifax's Avatar
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Discussion

Radical RC Mini Stick EDF Build


Hey there Radical RC fans! The purpose of this thread is document the building of a RAdical RC Mini Stick, EDF powered. But first, some ground rules.

#1.) I am a HUGE fan of Radical RC. This will be the only shameless plug for them on this thread. I claim no affiliation with them, I only enjoy their planes. If you have never seen their planes or have not visited their website in awhile, I strongly encourage you to do so. Dave has a lot of new planes with innovative designs. The nice thing about them is that they can be real barnburners or slow down to nice, sedate easy fliers, its your choice. Not only is the company fully stocked with just about everything you need, Dave is truly one of the nicest gentlemen you could meet. He always takes the time to stop and answer all your questions even if your not buying any of his products. His passion and enthusiasm really shows in his products and his business.

www.radicalrc.com

#2.) This will be mini stick #7 that I have built. Since Dave's planes seem to be growing in popularity, I will not exhaustively document the initial build of the Mini Stick. I will update with progress but since they build so fast, what is there to show? There are other Mini Stick build threads out there

https://www.rcgroups.com/forums/showthread.php?t=230894

so if you need, reference those. These planes are very easy to build anyway. My goal is to document the build (and flying) of the plane more or less after the covering is applied.

#3.) PLease feel free to chime in with suggestions, remarks, dirty jokes, etc.

#3.) Design parameters:
A fun, easy flying mini stick using EDF power built VERY light.


Equipment/Supplies
Mini Stick (version 1) kit.

Mercury CA Adhesives (thin and thick) throughout.

SoLite covering throughout

Berg POstage Stamp receiver

Azarr Ant.

Very light servos. Probably two 5 gram servos for V tail and a Hitec HS50 for ailerons.

Twin EDF Units (EDF 50's). Ive had these for at least 7 years looking for a home. I think these have been updated but for now, this is what Im going with. These have the original brushed motors (150's?). The rating chart states 73grams thrust at 7.2 volts. I can go BL if needed but Im sticking with these for now. Also, If I recall correctly, I think I remember someone over in the EDF forum claiming better performance if you restrict the air flow out of the duct by 10%, you improve performance. Its worth a shot.

2 cell lipo. Im not sure of the make and model but maybe something in the 500-600 mah range. The motor chart reads 3amp WOT. I generally use Deans conn's but might have to switch to GWS style for weight.

Not sure on the ESC yet. I have a 30amp but is too heavy for this project. I hate to have to buy a brushed ESC for this app. Maybe my fellow flying club (NCEF) members can help me out.

One of the biggest things looming right out of the gate is how (and where) to mount the EDF units. I initially thought it would be very cool looking to have them out at the wing tips but I was told they would do better closer to the center. For now, I will plan on having them next to (if not attatched to) the body. The EDF units have two raised lips that would lend itself well to a tyvek "band" that would go around it and secure it but I thing it would possibley distort the whole duct unit and at worse, have the impeller hit the sides. So for now, I will try to come up with a creative, lightweight way to do this. Any suggestions?

Mods:

I think I will go with a V tail. I remember Dave saying in another thread this might be a good way to go. Lets plan on that for now!

I think I will try and vac. form a nose cone for this. It should improve the looks of the boxy front and set it apart from other sticks.

I will use the original magnet wing latch. I generally use the nylon bolt but this wont set and speed records.

I will go with stock LE. I use carbon fiber for an indestructible wing but for weight, lets use the stick supplied.

You have your choice of a couple of different styles but I wont commit at this point since some of the parts will have to be custom.

Probably no landing gear. Although if it affords extra protection against knocking the EDF units off, I might consider but at this point no need. This thing will be gentle.

I think that pretty much covers it for tonight. Feel free to comment and Ill post again soon!

Dan
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Jan 14, 2008, 08:38 PM
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luger007's Avatar
Fun idea! Isn't Dave working on an EDF twin? IF you want a set of GWS A-10 Nacelles for EDF50 fans, I have a set of white ones you can have. They cost me $10 when I was going to do a pusher A-10 setup only to find out they are exactly the same size as the EDF 55 nacelles but thicker! I was trying to save weight!

Anyway, since I'm working on one of Dave's pre-production Das Mini Bipes and you are a fan or Radical RC planes, I thought I'd offer the nacelles to your cause. PM me if you are interested.
Matt
Jan 14, 2008, 11:05 PM
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Carnifax's Avatar
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Progress continues even though I feel sickly. Got the wing made up and already a dilemna. The Fan units are going to extend below the bottom of the fuselage which may be a problem on landing on the belly. See what you think.

I flipped it over to better illustrate and found I like the looks of it as a low wing Mini. I will sleep on it for now. Next will be the tail feathers. See you next time!
Jan 16, 2008, 01:46 AM
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Carnifax's Avatar
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I got the puchrods connected and set. I am not a huge fan of "buying" a solution, I would rather use a little creativity but they were on hand from a past project and they dont weigh much. Another problem creeps up. The light servos from Cirrus are shot from another plane. I guess those servos are more delicate than I anticipated because the gears are shot. I have always had pretty good luck with Hitecs so Ill switch to 50's throughout. Little extra weight but if the plane is heavy I can always switch out right?

Got the plane covered. I dont mind covering and Solite is pretty easy to use. I just kept the heat way down and go slow. Snugged everything up with a heat gun. More pics...
Jan 16, 2008, 02:11 AM
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Carnifax's Avatar
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Progressing ok. My next step will be addressing the nose cone. I think I will vac form one but first must make a positive mold. That will be next days work though, time for sleep.

Navin: "It's a lot of fun working and Mr. Hartounian is really nice. He's teaching me how to be impatient."
Harry: "Navin!"
Navin: "Well, I gotta go now. What do you think I do? Write letters all day?"
Last edited by Carnifax; Jan 16, 2008 at 02:34 AM.
Jan 16, 2008, 02:47 AM
Fly it like you stole it..
Tram's Avatar
Why wouldn't your fans adhere to CA?

I've used CA on them on a small lil' Bob-E-Cat thing I had.. CA worked like a champ?


Jeff
www.CommonSenseRC.com
Jan 16, 2008, 07:57 AM
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Carnifax's Avatar
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Jeff,

Good question. I guess I just assumed they would not. I know I dont want to CA them directly to the covering. Maybe I could make a couple of small balsa standoffs. Something easily replaceable in case they get ripped away. Thanks for the tip.

Dan
Jan 16, 2008, 09:24 AM
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dgarbern's Avatar
A flying buddy gave me his Radical RC e-hornet. After flying it a bit in its normal configuration, I was curious to test twin edf50's powered by 2 Medusa 5300kv motors. Fans are held in place under wing with strapping tape. Only other mod was a few minutes to make a pink foam nose cone. Not a speed demon, but it flies in 20mph winds with authority. I programmed the fans for differential thrust, but it didn't have much effect. Glides great, full throttle is about 100watts, 9 oz static thrust. AUW 13 oz with 3s 1320mah lipo.

Dave
Jan 16, 2008, 10:17 AM
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Carnifax's Avatar
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DGarb,

Nice Hornet. I have one in the "to be built" pile too.

Did you ever have any problems with the ducts coming loose on landings?

I think the Hornet has more mass than the mini stick and would surmise that they would be susceptible to shearing off. Glad to hear that the Medusa's handle that so well. I suspect that might be my next move too.
Jan 16, 2008, 02:23 PM
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Skymangler's Avatar
oops
Jan 16, 2008, 02:27 PM
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radicalrc's Avatar
Wow, It's amazing how close you are to my laser files. I've just finished it and will be cutting the first proto soon. I probably detailed this in earlier posts. But, I've got the fans out in front of the wing on pylons, longer wider lower fuse, 140 degree V, very low trike gear and my fuse is swept upwards in the back. More like the Mini Low Stick Photo'd. I've got the aileron servo so it's possible to inset it under a hatch in the wing at builder option. Magnetic "latch" wing. D-tube sheeting and the like. It's got all the normal V2 features (all my models 2007 on do) and some more.

I decided to move the fans out front and use the smaller fans for the very problem you discovered. It's the only way to get the bottom of the fans above the bottom of the fuse. This feature makes hand launch models possible and also means your less likely to drag a fan on a landing gear squishing landings. Also, my goal for this model is a really good handling ROG and touch and go machine. I've made the strongest wing EVER for one of my kits. So, I welcome the wicked ones to cram in all the balsa ripping watts they can. ;-) I feel it will be a real good handling machine that will make a good first fan model yet still be exciting for anybody well into this catagory. It should be possible to make it very fast but that's not my first goal. This is unusual for a fan model. Generally they are built by speed freaks for pure speed. That's OK, I just want something with a wider speed envelope.

Another reason for going with D-tube sheeting is to get the wing stronger for any landings that might have a fan contacting the ground. I didn't want to hear stories about ripped off leading edges and such. I fully expect you guys to take this model far over the top! My first one will run pure EDF-40's. If it flys well with those, it will fly well with any reasonable brushless system. Certain success is important to me. The world does not need another wallowing fan model.

It sounds like you'll get to play with the power system on the right wing area and model weight before I do. I'll be lucky to get to fly mine by late next week. Of course, we've got to cut the first one. I think it's perfect but they first trial kit is always full of bugs that take a while to work out. Missing parts and the like.

I like the E-Hornet fan idea too. Now that I've worked out a fan mounting pylon system it would not be very difficult for me to setup the E-Hornet for this also. I'd probaly build it around 55's or 64's.

It's always been my feeling that two fans are better than one. ;-) So, this is why my first fan effort is with a twin. A couple of years ago I played around with some foamy twin fan models in preperation for a project like this. I needed to get some stick and motor system time to get my mind around how to use these systems. I'm taking what I learned from those tests and what I already know to see how well I can do a real kit. So, time will tell.

I look forward to sending you a beta to build. I need a little time to get it at least 95% correct first. I always do two beta's for each model. I've already presellected the builder for the other one on this project.

Dave
Jan 16, 2008, 10:53 PM
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dgarbern's Avatar
Quote:
Originally Posted by Carnifax
DGarb,
Did you ever have any problems with the ducts coming loose on landings?
Not really, so far. As I mentioned in my first post, I was flying in strong winds, so my ground speed on landing was quite slow.
Jan 17, 2008, 12:20 AM
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Carnifax's Avatar
Thread OP
Dave,

Great to hear about your progress and thanks for weighing in. I thought about the ducts being "ground heavy" and I have a design in mind to correct this but lets see how this does first. I will include pics. I believe I will go brushless as soon as this gets maidened.

Little progress tonight, sorry no pics. Still battling the cold. Problems, problems. I have a Futaba 6x super and somehow the programming was "off". I will have to read the manual (who does THAT?!? I might as well stop and ask for directions while Im at it!!!). I hooked up a little CC esc and Medusa motor to center the servos. I thought one of the HS50's was shot. I knew I had a replacement gear set so I cracked it open and tried to force the replacement gear on and wound up knocking a pin off center. Turns out, the crystal in the receiver was bad so now I have screwed up a good HS50 AND replacement gear set. Oh well, live and learn, right?

I did get the rear linkage hooked up, tomorrow the ailerons and work on the nose cone. I did haul the vac former machine out of the garage though and dusted it off. The weekend forecast looks brutally cold so maybe this might see some dome action this weekend. Until tomorrow,

Dan


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