Ben, I'm going to be cutting one of these on the Rascal once it's up and running. There's a club member with an F-4 obsession that NEEDS one in his life.
F-4 Phantom - Twin 70mm EDF Monster!!
- Thread starter Mid7night
- Start date
I think a stripped-down version is a GREAT idea! I'm not 100% sure twin-50mm would be enough thrust, but if you really put it on a diet and do all the minimizing you talk about, it might actually be ok. It's just so BULKY at this size, I worry about the drag more than the weight. I think twin-64mm fans on a stripped-down version would definitely work.
AWESOME. Let me know if you want/need the DXF files for the machine.
Zephyr1
Elite member
Yeah, I hadn't looked at the weight disparity, the F-5 is under 1000g with over 1700g of thrust and the F-4 is 2400g, with 3600g thrust. With all of the minimizing I think i could get the F-4s weight down to 1600g, but I don't know how much less then that. To give it a comparable TWR I'd have to get it down to 1300g and I don't know how realistic that is. I think I'll try it with the 50mm fans, and if that doesn't work I'll up it to 64mm and I'd probably have to build the F-5 then!
Those are the nose gear brace pieces. There should be two, mirror images of each other. They are intended to glue to the side walls of the nose and keep the nose gear upper-mount pieces centered.
The nose gear "upper-mount" pieces are 3 identical sorta-trapezoid pieces. They have three straight sides and one angled. Those get glued altogether as one, and go on top of the nose gear. THAT whole shabang goes in between those two pieces you asked about.
Clear as mud?! Good!
EDIT: Oh wait...LOL...you're building the stripped down version which means NO GEAR. Yeah don't worry about those pieces. XD
The nose gear "upper-mount" pieces are 3 identical sorta-trapezoid pieces. They have three straight sides and one angled. Those get glued altogether as one, and go on top of the nose gear. THAT whole shabang goes in between those two pieces you asked about.
Clear as mud?! Good!
EDIT: Oh wait...LOL...you're building the stripped down version which means NO GEAR. Yeah don't worry about those pieces. XD
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Zephyr1
Elite member
Lol that's good. I'm sure it'll be most helpful for whoever tries to make it with landing gear, i used all mine on my Amerika bomber... Do you have any pictures or any advice on how to mount the vertical stabilizer to the fuse? Especially in regards to the folded triangular piece.
Before you mount the vertical, you need to finish the fuse/nacelles and top/rear turtle deck.
If you're doing a double-layer tail, glue the two vertical pieces together first (either with hot glue or 3M77 spray - spray is lighter). I recommend doubling the tail, because of its size, but for your light-version you might want to skip this and just go with one thickness.
The vertical tail slides into/onto the rear of the fuselage, centered. The slot should slip over the rear of the nacelles. I found it helpful to lean the tail to one side slightly when sliding it in, and also squeeze the turtle-deck a bit to increase its height, because the tail slot has a reverse-taper.
The folded triangular piece is for closing out the gap above and below the horizontal stab as it comes out of the tail. I've built 3 of these jets so far, and I've done that area a little differently each time, so my best suggestion is to cut the pieces out a little 'big', and test fit them several times before gluing them down. Obviously put the horizontal stab in first, and sort out the elevator and everything...THEN close out the gaps with those pieces.
Sorry I don't have any great pics of this process, but I hope that description helps.
If you're doing a double-layer tail, glue the two vertical pieces together first (either with hot glue or 3M77 spray - spray is lighter). I recommend doubling the tail, because of its size, but for your light-version you might want to skip this and just go with one thickness.
The vertical tail slides into/onto the rear of the fuselage, centered. The slot should slip over the rear of the nacelles. I found it helpful to lean the tail to one side slightly when sliding it in, and also squeeze the turtle-deck a bit to increase its height, because the tail slot has a reverse-taper.
The folded triangular piece is for closing out the gap above and below the horizontal stab as it comes out of the tail. I've built 3 of these jets so far, and I've done that area a little differently each time, so my best suggestion is to cut the pieces out a little 'big', and test fit them several times before gluing them down. Obviously put the horizontal stab in first, and sort out the elevator and everything...THEN close out the gaps with those pieces.
Sorry I don't have any great pics of this process, but I hope that description helps.
The conventional elevator felt a bit more stable, less sensitive in pitch, but that might be my throws at the moment. For a lightweight build, I would suggest regular elevators. Yes there are two servos, but I still think that's lighter than all the torque rods and connecting rods for the stabilator assembly.
Zephyr1
Elite member
Props!?! I thought this was an EDF?
That's Ben's first A-4, Dan, this is an F-4. It's a very common mistake, i'm sure.
Zephyr1
Elite member
Thank you for the kind words Ben! I maidened it today! I tried running it off of a 3s and it flew really well! No crazy speed but I was saving that for the 4s. On the third flight the one esc gave out, and I'm not sure why. I've since replaced it and should be good to go for tomorrow! I'll post a video then. Again Ben, thanks for all your help it's an amazing design!
PS I do know that the canopy should be further forward...
PS I do know that the canopy should be further forward...
Sotm
Member
Questions
!. Does your F4 have a functional Rudder?
2. Is the stab parts in the PDF files for conventional elevators? It appears so, and if it is what are the changes (shape size) needed to go full flying stab?
3. Did you know that the two rudder pieces in the PDF are both right side images instead of a mirror for one?
Enough for now. It's still an awesome build dude!
!. Does your F4 have a functional Rudder?
2. Is the stab parts in the PDF files for conventional elevators? It appears so, and if it is what are the changes (shape size) needed to go full flying stab?
3. Did you know that the two rudder pieces in the PDF are both right side images instead of a mirror for one?
Enough for now. It's still an awesome build dude!
!. Does your F4 have a functional Rudder?
2. Is the stab parts in the PDF files for conventional elevators? It appears so, and if it is what are the changes (shape size) needed to go full flying stab?
3. Did you know that the two rudder pieces in the PDF are both right side images instead of a mirror for one?
Enough for now. It's still an awesome build dude!
1) Yes
2) Yes, all the major parts are there, no size change needed. You will, however; need to follow what I did (or something similar) to implement the Stabilator.
3) Yes ... but a mirror image of an identical part is the same thing.
Thanks!
