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Follow up To Mid7night's F-4 Phantom - Twin 70mm EDF Monster!!

Sotm

New member
#21
Dry Test fit of EDFs

Just some quick pictures of the test fit of EDFs. I used a vinyl "For Sale" sign for the thrust tubes. A little fun to roll and glue (Hot Melt Glue) , but some tape helped. I think I might try a detachable wing. Just got a new aircraft carrier and it is a little smaller than the previous one. Removable wing will help. Details after I figure it out.

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Still waiting for ESCs before permanent mounting.
While waiting I made an F4 chuck glider.
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Uses less than one sheet of foam board. The plans are attached here. They don't show it , but I made two doublers for the nose about three inches from tip back. Both for added strength and nose weight. It flies without any more nose weight but should be slightly more nose heavy.
 

Attachments

Sotm

New member
#22
EDFs and Thrust Tubes

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Completed the fit-up and install of the thrust tubes and EDFs. Used a large vinyl For Sale sign to cut the thrust tubes out of. Worked great. A little paint before install. As well I have done some painting of the fuselage and wing.
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Still waiting for ESCs so I haven't placed the battery tray yet.

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I am making my wing removable for transport purposes. I used some light ply 1/8 inch for the mount plates and doubled it with 1/8 5 ply epoxied where the screws would go. I am using 8/32 nylon as they are readily available from Lowes. I just put the wing in place and held it there while I drilled the pilot holes all the way through the ply plates in the fuselage. Then removed the wing, drilled the ply to the proper diameter for tapping and tapped them for the 8/32 nylon bolts. Made clearance hole through the wing and I will use a large nylon washer on the outside of the wing to distribute the load over the foam board some. Now if I could just get those ESCs and get them mounted I could check CG and place the battery tray.
 

Mid7night

Jetman
Mentor
#24
Lookin' GOOOD! I love that you did a removable wing. That's definitely something I want to incorporate, at least as an option, into my plans at some point.
 

Sotm

New member
#25
Lookin' GOOOD! I love that you did a removable wing. That's definitely something I want to incorporate, at least as an option, into my plans at some point.
Not the prettiest, but they work.
There are three mounts on the front only because I tried to do just one first in the center out of the duct area. It didn't hold the outer edges of the wing well enough with it being so wide in that area. So I then added the two outer ones, which will only be the ones I use. Don't want to try and remove the inner one for fear of destroying the foam board there. The back ones are out side of the thrust tubes, which is good.
 

Sotm

New member
#27
Finals - maiden

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Couldn't get a large nylon washer to fit so I 3D printed 4, 1mm thick ones to keep from pulling the wing bolts through the foam board.

Well I got the second ESC installed and did a CG check. She's plenty nose heavy with the 4S 6000 mah battery as far back as I can place it. If I had it to do over again, I'd move the EDFs another inch and a half back or more. Then lengthen the inside center duct walls to make even more room to move the battery even further aft.
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All up ready to fly weight is 5.8 pounds actually weighed. Each EDF, according to FMS, puts out 1630g of thrust. That's 3.59 pounds of thrust. We all know that we never get what the mfr. says we will get. I figure if I get 3 pounds each that's still 6 pounds of thrust for a 5.8 pound plane. That's better than 1:1 should be plenty of go juice!

Now, since I live in western Washington, I need to wait for some dry calm weather before I try a maiden.
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Some final pics.

Here is a template for the intake duct covers:
 

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Sotm

New member
#31
Sweet!! Glad to see it all come together! Can't wait to see your maiden. :D

Nice job on the main strut covers too. ;)
Actually the strut covers came with the main gear that I used. I bought the F5 freewing main gear and plastic mounts from Motion RC. The gear came with the strut covers. I just re-painted them to match.

Did you get that elevator deflection for me yet?
 

Sotm

New member
#32
F4 add ons

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I needed a little tail weight so I decided to make a tail hook. This one is 3D printed and only a few grams. It is non-functioning, but I am considering developing a functioning one. I have a 3D printed one that is fully functional for an 1100mm T-28 that is self contained in that the servo that actuates it is held in the assembly itself. I may try and mod it to look more like the F4 hook. Let's get the maiden done first. Still waiting on good weather up here in Washington state. Hey Ben, could you send some of your good weather this way?
 

Sotm

New member
#36
have you managed to maiden it yet?
Not yet the rain and windstorms in here the great Pacific Northwest have kept me at home and off the flying field. I will respond to the battery location that you asked Ben. I moved my edfs back 1 1/2 inches from Ben's location and with the 4S 6000mah battery as far aft as it will go I will still need some tail weight to balance at the CG.
 

Sotm

New member
#37
have you managed to maiden it yet?
Not yet the rain and windstorms in here the great Pacific Northwest have kept me at home and off the flying field. I will respond to the battery location that you asked Ben. I moved my edfs back 1 1/2 inches from Ben's location and with the 4S 6000mah battery as far aft as it will go I will still need some tail weight to balance at the CG.
 
#39
Maidened mine today and it flew great if not abit nose heavy, thanks for the plans and information on here .
Photos and modifications later ��
 

Sotm

New member
#40
Maidened mine today and it flew great if not abit nose heavy, thanks for the plans and information on here .
Photos and modifications later 😁
My first attempt went very wrong. Even though it was slightly nose heavy, the flying stab was off in the up direction way too much and when it broke ground it went straight up! Tried very hard to get it under control but after about six porpoises I cut power and it nosed in. Wing survived but I am rebuilding the fuse right now. Going to put a wing incidence meter on both the wing and stab first this time with both at 0 degrees.