|Sep 04, 2001, 08:09 PM|
Wattage F-22 EDF conversion..motor/fan choices
I'm tempted to try converting the new Wattage F-22 to EDF, but I may want to just throw a 480 on the back of it with a prop and concentrate on bigger projects like the new EJF F-86.
I cut the fuselage in half right behind the hand holds and traced the outline onto paper to get some measurements. The middle of the fuse between the engine humps is 2 7/8" deep. If I went with a single MF480 it would have to stick out of the bottom a bit, making full ducting difficult. Might be too heavy anyway.
Two EJF EDF400s will fit side by side, but the inlet area meausured from the frontal view (the inlets are swept back a bit which may increase the inlet area a bit) is about 2.14 sq in, which is only 58% of the EDF 400's fan swept area of 3.71 sq in. Cheater holes would be needed, and I don't like to have them unless there's no other way. If I could get 7 ounces of static thrust from each fan once installed I might get a decent climb rate, but with the drag of cheater holes my speed would be limited. The EDF400 fan's rotor isn't very sturdy and has moderate to low pitch, so pitch speed might be low. I want to break 40 mph for sure, and Zagis fly about that fresh off the charger. You guys with Electroscreamers and EDF400s on them, how fast would you say you are going on this setup?
If I go with a single 2.5" fan I can probably get 120% fsa at the inlets. I'd be pumping less air so I'd have to have a high power package. I'm thinking the Graupner speed 400 fan of 2.5" diameter. Looks fairly sturdy from the pics at Hobby Lobby. Not sure if they have a 1/8" adapter for it. I'm thinking of the MPI Promaxx Cobalt motors, maybe the 11 turn version. Not sure what kind of amps that would draw. The Zone has been down so I haven't been able to research the amp draw on the 11turn and a MF480. I'd like to use my new CP1300s. I'd guess this 2.5" fan from Hobby Lobby will pull about 4-5 amps less than a MF480, but not sure without real data from others.
I had considered the WeMotec Microfans and Speed 300s but with the vibration problems that some are having I decided against that for now, plus I'm trying to avoid even messing with ferrite motors in EDFs, the power that I want just isn't there, plust it'd mean buying two of the Hacker B20s instead of just one brushless motor.
Oh well, I should probably just throw a prop motor on it with a gearbox, I'd get good climb rate. My buddy has the Kontronic Drive150 direct drive with on his and it goes ok on 8 or 9 600AEs, but vertical performance is on the weak side. It'll loop barely from level flight, kinda flops over the top unless you dive. Gotta get him to try 10 cells next. He was running a Cam 5x5 and it was running hot, about 13 amps on 8 cells. Switched to an APC 6x3, speed was the same, climb was a bit better, and amp draw was down quite a bit, getting four minutes now at least.
Getting a square chunk of foam in the fuse before cutting ducts for a fan/fans using templates might prove challenging to get a good fit, but hey, that's what filler is for right?
Oh decisions, decisions.
|Sep 05, 2001, 11:43 AM|
Weeeeeellllllll, Robert at the electric Jet factory was selling cut down mini fan 480s. The rotor is 66 mm I think. They are a good drop in for the EDF 400. When I got mine, they did not come with shrouds, so I had to make by own, but so what. The regular mini is good for 16 oz with a race 480 bb and Robert told me figure around 14oz or so from the cut down fans. Sounds like maybe the key for you, no cheater holes, beffy mini fan rotor, no belley hump, and go brushless if you want with no worries . I have one sitting in my Kevin Cox nearly complete F-18, no air time yet though .
|Sep 08, 2001, 02:56 PM|
Joined Sep 2001
I'm the buddy Ed is talking about. I did put the 10 cell on her and flew this morning. The differance between the 8 and 10 cell is like night and day. The vertical is fabulous, and the top end went from cool, to i'm worried about strctural limitations. Ed listen to Gregg, put a prop on it and do the F-86 up right. Plus i want to do some formation flying. "Raptor 1 this is 2...ready break...NOW.
|Sep 09, 2001, 06:40 AM|
United States, NV, Las Vegas
Joined Dec 1996
Whats up Ed!
Actually, do you know who Bill Floyd is? He lives here and bought the kit. He's planning to make a mold of it, then make the whole thing molded from Kevlar with an enlarged center to fit the fans perfectly. Not sure when he'll be done, but the Kevlar will weigh less and be stronger than foam, plus itll fit the fans!
I'll let you know when I hear more on that!
|Sep 10, 2001, 01:21 AM|
It took a few seconds but I think I know who you mean. I only know him by his first name but when you said molded and kevlar I knew who you were talking about. He flies at the Silverbowl, older guy about mid 40's. He built a vectored thrust semi-Zagi ship, man that thing would swap ends with the vectored thrust. Saw him in the hobby shop about a month ago. We've been flying at the north field for the past few months, haven't been able to go to the Silverbowl in a while.
Bill flys at that park in the detention basin on Spring Mountain and Durango during the week at night sometimes with this other guy Dan. Never met them out there, my Zagi is trashed.
I ordered the Kontronic Fan Drive yesterday for the F-22, going to go with a single 2.5" fan. Guess I'll have to use the CP-1300s, the KV on this thing is 2800 vs 2300 for the Drive 150 that Radar Lock is using, so the amp draw will be higher. I decided on one fan because I wanted to buy one motor for now and inlet area is not abundant. Two EDF400s might give great static thrust but top speed might be limited.
Test flew a 4.8v Speed 400 in a 2.5" hair dryer fan today on my E-Sparrow. It's got an Ace foam wing, shoulder mounted on a box fuselage. On 9x600AE it was pulling 15 amps and the batteries didn't like it, motor kept cutting out for 1/2 second at a time. The damn fan just isn't putting out much thrust, can barely stay level, climb out of the question. Tried it unrestricted then with reduction cones, still no good. May try a 6V motor next but will probably just give it up. Ferrite motors in EDFs just don't thrill me. I'm sure a better designed unit like the Wemotec would be better, the blade clearance on this fan is large.
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