Posts: 248
Joined: 10/22/2004 From: USA, USA Status: offline
My quest for an inexpensive EDF plane has begun. I wanted something that looked cool, yet would not cost much. I also wanted something light that could be easily hand launched. I finished what I think are the hardest parts so the rest should go pretty quick now (at least that is what I keep telling myself). Just need to attach the wing, aeileron servos, rudder, elevator, finish canopy, sand and paint. Ok, maybe it won't be as quick as I'm hoping for... This is my first foam kit and first attempt at an EDF. I spent some time making a dual exhaust that is the correct size for the MF 480. I was going to make ducts for the intake but I'm getting impatient and may just leave it as is with the intake ring inside the semi-ducted stock layout. Original plan was not to use the intake ring and fully duct the intake up to the MF unit. The 3 turn Typhoon motor is putting out about 25 ounces of thrust with the existing setup when I cover the top so that it is only sucking in air from the intakes. Per MotoCalc I should get about 28oz. I question if fully ducting the intake will make enough of a difference on this plane to be worth spending the extra time on it? I am using a 4 cell LiPo pack. Let me know what you guys think. A lot of this is new to me so I hope I am on the right track.
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Joined: 12/8/2002 From: Valdese,
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I think youre on to something there but I have a quick question regarding your stabilator pivot tube location. I looks a little aft to me . I have built 4 of the pusher versions is why I ask. Otherwise I think the tailcones look awsome!I am curious to see how it comes out. If you are at all concerned about wt. I suggest to forego the rudder. You will not need it if you fly it like a jet, Bank and Yank.
Posts: 248
Joined: 10/22/2004 From: USA, USA Status: offline
Hi Vicman,
I am not putting in rudder control. I meant to say I had to install the vertical stabilizers. The pivot tubes are located in about the same location as called for in the plans. (It was a tighter squeeze than I anticipated to fit the servos between the exhaust.) However, she has a little bit of a fat rear end (in height) to accomodate the MF480. (Don't tell her I said that about her butt )About 18mm fatter than stock (added 3 sheets of 6mm Depon to the floor of the fuse for the extra room.) The tip of the exhaust tubes is about 3/4" longer than the standard fuse. Other than that the rest of the plane is made with the pre-cut parts. One of the sheets I extended all the way to the nose cone for extra strength and to give me more area to round out the fuse a little more when I sand it. Oh, I also cut off about an inch inside the fuse so that it would not be too close to the fan to create poor air flow. That does not change the overall length of the plane. Maybe optical illusion from photo on the pivot point?
Ignore the freeway photo, clicked on wrong one uploading.
< Message edited by PilotSmith -- 3/2/2005 7:49:10 PM >
Posts: 248
Joined: 10/22/2004 From: USA, USA Status: offline
I placed the remaining loose pieces on the fuse with a little tape to hold em in place to get an idea what the finished thing will look like. Dang, work is a real pain. It gets in the way of my hobby. Time to go earn some money now...
Vicman, why 4? I hope 3 did not crash?!?
< Message edited by PilotSmith -- 3/2/2005 7:52:41 PM >
Do you have a clear picture of the whole inlet system. This seems to the where most of the conversions fall short, the bit you have shown is better than the ones I have seen in the past. Good luck.
Posts: 6080
Joined: 12/8/2002 From: Valdese,
NC, USA Status: offline
No crashes. They were gifts I have worn the bottom out of mine and had to replace it from landing so many times. I plan on building another one for me in a few weeks. Too many other planes in the way and that work thing too I like what you have done and am anxious to hear how it does. I just got a Kamdax Mig yesterday, this will be my first suara' into the DF world.
Posts: 248
Joined: 10/22/2004 From: USA, USA Status: offline
Hi Eric,
I can see that being the case. I thought I would just use the intake as is with the minor modifications I made to give a bit more clearance for the fan intake. With the top of the fuse off where it can suck in all the air it wants I recently measured 26.5 ounces (measured by exhaust blowing against a digital scale so maybe actually a little more?) Then I put the fuse and wing on and it dropped to 25 oz which I thought was an acceptable loss. Then I ran the wires from the two elevator servos and the brushless motor through the inlets into the center of the fuse. I also installed the two aileron servos that also protrude into the intake area. I tested it again after doing that and thrust fell to 19 oz! So it looks like I will need to properly make some ducts for the intake that fully encompass the fan unit to avoid the turbulence the wires and servos apparently are now causing. Arggg! I thought I was just a short way from finishing this thing but that no longer appears to be the case.
Vicman, glad to hear you have not crashed them! I was getting worried for a moment.
quote:
ORIGINAL: Airx
Do you have a clear picture of the whole inlet system. This seems to the where most of the conversions fall short, the bit you have shown is better than the ones I have seen in the past. Good luck.
Posts: 248
Joined: 10/22/2004 From: USA, USA Status: offline
Exhaust tube is in the way to use the solid rod. I had to put a servo on each side or have a rod going through the exhaust which I thought would be bad for the air flow.
When will you have your Mig flying? I was thinking about that one or their Mirage kit a while ago but expensive.
I'm getting too impatient to build these things. At this point I'm thinking maybe I should have just gone with the HET F18. The HET seemed heavy so I was hoping to get something close to it in size and appearance but lighter (and less expensive) with the foamy kit. But the final weight of the foamy is going to be about 30-31 oz ready to fly including the 4 cell pack so I'm not sure how much weight I am saving. I wonder if the 30.5-37oz weight for the HET is the total fly weight with battery?
< Message edited by PilotSmith -- 3/3/2005 5:18:51 PM >
Posts: 248
Joined: 10/22/2004 From: USA, USA Status: offline
Eric, Here are the photos of intake, version b... Almost finished with the intakes now. Removed intake ring and made ducts. This should provide for clean air to the fan as air is no longer going around servos and wires.
I think leaving the split clear plastic out would let you have better intake airlow to the fan because the thin edges will exclude a lot of airflow from the ducting. If you leave it in make sure to fair in the area arround the interface of plastic to the foam that will give you the best that you can do in this application.
Think about the outlet and how the thrust is reacting to the open area behind the aircraft, the air flow leaving the outlet react with only open air so the force the plane will see is only that reaction. Taking a thrust reading by focussing against a scale face is just changing the physics that are in force with real life applications, try pointing the nose down on the scale and letting the force of the airflow reacting to open air give you a correct reading because pointing the airflow to the scale face changes with the distance to the scale face which is a pressure change which is not present in real physical application.
I want to see you be succesful. Good luck.
Eric B.
quote:
ORIGINAL: PilotSmith
Eric, Here are the photos of intake, version b... Almost finished with the intakes now. Removed intake ring and made ducts. This should provide for clean air to the fan as air is no longer going around servos and wires.
Printable Version
All Forums >> Electric Aircraft Universe >> Electric RC Jets >> 3D-Foamy F18 EDF Mini Fan 480 Project 
3D-Foamy F18 EDF Mini Fan 480 Project - 
. I have built 4 of the pusher versions is why I ask. Otherwise I think the tailcones look awsome!I am curious to see how it comes out. If you are at all concerned about wt. I suggest to forego the rudder. You will not need it if you fly it like a jet, Bank and Yank. 
)About 18mm fatter than stock (added 3 sheets of 6mm Depon to the floor of the fuse for the extra room.) The tip of the exhaust tubes is about 3/4" longer than the standard fuse. Other than that the rest of the plane is made with the pre-cut parts. One of the sheets I extended all the way to the nose cone for extra strength and to give me more area to round out the fuse a little more when I sand it. Oh, I also cut off about an inch inside the fuse so that it would not be too close to the fan to create poor air flow. That does not change the overall length of the plane. Maybe optical illusion from photo on the pivot point? 
I have worn the bottom out of mine and had to replace it from landing so many times. I 
I like what you have done and am anxious to hear how it does. I just got a 
I thought I was just a short way from finishing this thing but that no longer appears to be the case. 
