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Old Nov 23, 2012, 01:43 PM
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Freddie B's Avatar
Omaha Nebraska
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My 22mm EDF testing.

Not everyone will care to see the details of the power unit, but for those that do here we go.

I took my 22mm BimRC shrouds out of storage and started looking for a 7mm motor in my stockpiles. All I could find was some 7mm motors out of the Air Hog 3omm Jetscream edf fans.

First I took a picture of the compairison of a Air Hog (AH) 30mm EDF, and a Bim22mm EDF. WOW, Right? Huge differance! The 30mm EDF unit is 185.9% larger surface area than the 22mm, or looking at it different, the 22mm unit is 53.7% the size of the 30mm EDF unit. Amount of air that can pass through the EDF unit is a huge factor on all performance aspects.

Next I weighed the Air Hogs 30mm EDF, and an assembled BimRC 22mm EDF using a home made rotor arrangement. Identical weights at 4.2g. I will hope to get the weight down slightly when I receive BimRC Rotors very soon.

Since at first my only source of 7mm motors I found were from the Air Hogs 30mm EDF, that is what I started with. Motor specs were 7mm OD can motor, brushed. Measured 1.8 ohm on the voltmeter, and a 0.8mm shaft diameter. End cap is white.

I mounted this motor and spun it up on the scale, using the stock 2 blade EDF "rotor/prop" that came in the JetScream and FoxFire jets. Using a 100mah, 20c, 1 cel Lipo. The 29mm 2 blade prop, no shroud, pulled a maximum of 8.0g thrust (7.7g average), 3.9v under load, 0.6A measured, 2.34 watts.

Now I have a point of referance to judge 22mm output in comparison to a given 30mm production unit. My initial observation is that UNGN has tests results showing equal to more thrust obtained on the BimRC 22mm EDF as the Air Hogs 30mm is putting out! Could this be so? A 47.3% reduction in size and equal output, now that would be something!

Fred


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Old Nov 23, 2012, 02:12 PM
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Lets apply some tests at 22mm, hardware needed.....


So needing to be supplied with Flyzone motors, and BimRC rotors, the waiting game began. I wanted the do my own tests NOW! So using the AH motors I had on hand was my only option. So what to do????

I decided to make some small aluminum rotors out of thin .007" sheet stock (Roof flashing material). Easy to cut with even scissors, and light but strong. So I had tought for some time how would I mount these to such tiny shaft diameters? So I decided to make tiny prop adaptors! My first adaptor needed to fit a 0.8mm shaft! Yes that is .032" in diameter. I decided to make the threaded shaft a 2-56" thread, which is the Imperial Standard equivilant of 2mm, or say 2.2mm give or take.

I used a nylon washer, and even made an aluminum prop nut to save as much weiight as possible. Yes metal weighs, but surprise, so does plastic. Ended up with a prop adaptor that is over 0.3g, but under 0.4g. Not bad. Tiny yes, but it worked wonderful.

Next since I am no guru on rotors, I made two 4 blade units, and one 6 blade unit. I started with a disk, drilled some holes for where the vanes would end and be bent to required angles. then sized and fitted everything to a size I thought looked about right. I did bend an undercamber airfoil into each vane, then twisted in some pitch. As I tested the unit, I played with pitch and curve until I was getting the most from the parts.The 4 blade small vane and 6 blade wide vane rotors gave the best performance.

Rock science....no. Modeling magic....yes! Got to love making your own rules! (or not )

Fred


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Old Nov 23, 2012, 02:37 PM
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I mounted the 22mm 4 blade small vane aluminum rotor first, and ran it up simply held in my hand and hooked up to the Watt Meter. With a instant reading of 4v, 0.6A, 2.4 watts, I was pretty excited. This is what the Air Hogs 30mm prop and motor were measuring!

So I quickly mounted the EDF to my thrust stand and scale and played around with it. many adjustments to the vanes and the maximum thrust was 7.2g, with an average more in the 0.6's, and still pulling about the same power out as I was using this same motor on the AH 30mm production prop. Knowing this 1.8 ohm motor is not as hot of a wind as the Flyzone "Black" motor, sure made the waiting game to get my own FZ motors seem to get longer!



Fred


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Old Nov 23, 2012, 10:18 PM
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Last on the subject of motor testing for now.

So I got the "Black" 7mm motors from Flyzone, and they are a 1.1 ohm powerhouse for their size. I'll post more data later. However compared to the Airhog 7mm motors, these Flyzone motors put out a lot more RPM. The homemade 6 blade rotor I tried, on AH 7mm motor that was only pushing 6g thrust consistant. Placed it on the new Flyzone 7mm motor and it put out 8.9g thrust with only around 0.5A. So there is room to grow. Quite shocked to see 9.3g thrust on a fresh battery in a 22mm fan using brushed motors. These motors should be able to burst about 1A, so if I can get one running at 0.8A and pushing more thrust I would be one happy camper.

What I did determine is with the potential of 9g of thrust from a 7mm motor, I am ready to make the airframe and will try to keep the weight down as best I can. In other words it is now worth the time and effort because the potential for enough power for flight I believe is there.



Here is a breakdown of 7mm motors as available from several sources but this list was a generous contribution from Bob Selman. According to Bob, he does carry the quality 7mm motors from Walkera and is a USA Distributor of these and other quality products. Here is the response on the 7mm motors:

Bob's Long Can 7mm motors are the Walkera motors. Their resistance is 1.4 ohms.

Orange 3.3 ohms Didel/Super Slick

Red 2.3 ohms Didel/Super Slick

Blue 1.7 ohms Didel/Super Slick

Long Can 1.4 ohms Walkera quadracopter

Black 1.1 ohms Flyzone Playmate


Not only did Bob answer all my questions with great information, he also pointed out something we can all be grateful for. Note above that Bob has tested the Black Flyzone motors from the Playmate, AND included that information to help us all out. This is a 1.1 ohm motor and the hotest wind I have any knowledge of. UNGN is using these on his tests, and I had ordered some myself. I now have my Flyzone motors and will test them against the AH motors I already tested.

Thanks again Bob for the great data and everyone Do visit Bob's website at BSD Micro RC, LLC..

Fred
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Old Nov 23, 2012, 11:48 PM
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Fred, Kev gave me a bunch of the 22mm shrouds to kickstart my micro projects and this info will help a ton
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Old Nov 24, 2012, 12:21 AM
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very cool Fred! love to see inventive initiative at work

Joe
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Old Nov 24, 2012, 08:07 AM
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Quote:
Originally Posted by MustangAce17 View Post
Fred, Kev gave me a bunch of the 22mm shrouds to kickstart my micro projects and this info will help a ton

I am happy that this will help you too. I was looking to get into something right now to challange my tinkering thirst, and the 20mm projects had been on the back burner too long. Now I just got to get a light enough airframe to suit. I don't want to go brushless yet because the size would have to increase some since weight would go up. I do so hope to see some of your work on some micro stuff soon too!


Quote:
Originally Posted by sloperjoe View Post
very cool Fred! love to see inventive initiative at work

Joe

Thanks Joe, you are very kind. Hope something good comes out of all of this! LOL.

Fred
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Old Nov 24, 2012, 08:39 AM
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The heart of it all.......


So here we go this is the bulk of the building needed for my airframe. Since this is a Delta Wing most of the work is in the fuselage. If you look at the photos carefully you will note that after sizing the "blue prints" to 1/48th scale, I took a few key formers and made some templates. The templates are sized slighly over on the outside, and then the internal shapes I needed were cut out on the inside. The hot wire cutting I will use will slightly undercut the size so my webs are left a bit larger on the template. Nothing complicated at all as the .007" aluminum roof flashing material cuts with scissors, a hole punch, and Dremel tool with sanding drums.

Most templates are used twice. Each fuselage section will mate up to another so the mating edges will have the same template when I cut out the respective section. If you note photo two, you will see the paper shapes cut from the blueprint to draw the template shape onto the aluminum. These are 1/2 paper templates so I just flip them mirror image style.

Further the two fuselage sections where the fan tube meets up to the collector/transition section will use two different templates. these two templates are identical on the outside, but differ on the inside to get the internal design I need for construction. These are templates 5 & 6 seen in photo number two below (left to right).

I do hope my explination is clear. If not probably further photos will help. There will be sanding involved to final shape and blend everything also. All duct work is built in and this should help keep the weight down.

Fred


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Old Nov 24, 2012, 09:03 AM
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Cutting Fuselage sections.


Because everything is so small on this build, I used fairly cheap and ready available foam cutting devices. No need to go about building fancy foam cutting devices or needing to find a good power supply. This makes it easy for anyone to do the same thing I did here. (hint, hint)!

A good one to own is a foam table arrangement made by Marvy Uchida of America, and available from Hobby Lobby (The craft store chain). Suggested retail is $34.99, and is available direct from the manufacturer.

This and/or my small hand cutting wand from Woodland Scenes are all that is needed. The hand help device is actually $5.00 more, or $39.99 and most hobby outlets plus anywhere that sell model Railroad supplies should carry it.

Fred

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Old Nov 24, 2012, 09:18 AM
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Parts flying off the assembly line.....


So a couple test cuts were done on some cheap white packing foam. Then I did the same on some Pink foam. Weight was just slightly more on the pink (0.1g average per part) so I went with the pink foam. Less filling, easier sanding, and I like the density better!

This is the nose cone. I used a round template on one end, and a sewing pin head on the other. This is one part that needs to be cut a bit oversize so you can shape it conical like a bullet. The inside was hogged out and smoothed using my Dremel tool about 1/2 depth.

The sewing pin was replaced with a section of 0.8mm carbon fiber rod to give a bit of crush resistance and strength to the fragile point on the very end. This will prevent needing to glass or reinforce this area. Oh, and worried about impailing someone with the needle like end? Before each flight I will put a heatshrink bumper on it as insurance! Rough sized now it only weighs 0.2 - 0.3g with the CF probe installed. Encouraging.

Do understand that during this whole process of cutting fuselage sections I ruined around 3-4 different sections getting my groove back on with the wire cutting. But this goes with the territory. I is very easy to just cut up another part as they are fairly small.

Fred



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Old Nov 24, 2012, 09:46 AM
Lee Liddle
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Carrollton, Tx
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signed on, good luck
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Old Nov 24, 2012, 10:45 AM
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Originally Posted by Knife Liddle View Post
signed on, good luck
Thank you. This will not be a rocket powerd speed demon like some of the micro jets, but at this scale it doesn't take much to look the part!

Fred
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Old Nov 24, 2012, 10:52 AM
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Next the cockpit section using round template #1, and Template #2 which looks like a contoured rectangle. Weight between 0.3g - 0.4g. I left the webs a bit thicker on this section since it is frontal, skinny, and will take some landing loads.

Fred
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Old Nov 24, 2012, 11:33 AM
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Next the intake section was cut using template #3, and template #4 which is half way to the fan inlet. Do note that the cockpit section using template #2 fits in the solid area of template #3. The weight of this section came out between 0.7g - 0.8g. I hollowed out the center section by hand using my Dremel, but if make another one later I will add internal cutouts to my templates.

Fred
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Old Nov 24, 2012, 11:43 AM
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Next the intake collector transition section was cut using template #4, and template #5. Template #5 is where the front intake of the EDF Fan unit will rest. The weight of this section also came out between 0.7g - 0.8g. I hollowed out the center section (it tapers but does not go all the way through) by hand using my Dremel and sort of screwed it up. After some careful repair using some silkspan and glue, then lightweight filler I wif absolutely be more careful next time!

Fred


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