F-4 Phantom Build Notes with Video - RC Groups
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Jan 17, 2014, 02:13 PM
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F-4 Phantom Build Notes with Video


I decided to do another Phantom build, make a few changes to the original and plans. I originally did these because there weren't great simple plans for a phantom at the time. I'm not a big fan of mid mounted engines or box fuses, I'd rather have a slim profile, gives less drag in the air and is quieter. It does require you to mount equipment on the bottom of the wing has the battery mounted on the front side of the nose, but I'm ok with that. Due to the thin profile the wing hits the fuse further forward than on a normal fuse. If desired, you could alter the top view of the wing to include the intake profile and nozzle profile on the rear of the wing so that the top view was more representative, I considered this and decided to leave it clean. If you do this you may need to do some glide tests to confirm CG did not shift as the intake profile will add forward wing area. The wing is not mounted on the bottom, but is in a slot, I did this to give a bit of area under the wing to mount the electronics and not get destroyed on landing.

Flight video at:
F-4 Phantom parkjet flight 1 (4 min 18 sec)


Here is the Rocket boosted flights...

F-4 phantom scratch built parkjet/rocket boosted glider (2 min 0 sec)


For this version I used ailerons driven by a single servo on the bottom and a full flying tail. For the tail I used an aluminum pivot tube in the body and the tail pieces also have an aluminum tube in each one. I slid the tail surfaces on a carbon rod passed through the pivot tube and CA'd them in place after I made sure they were parallel.

The plans are just templates with CG marked. There are many ways you can do this plane and a lot of the details are up to you.

Make sure when you print out the plans you do with with no page scaling and borderless, check the marked rulers and be sure nothing was scaled. Tape the wing sheets and fuse sheets together and cut out the parts.

For the wing, it is simple, cut out the parts, round the edges, cut a v groove and glue and tape the spar to the bottom of the fuse. Then cut the wing tips, sand at a shallow angle(10 degrees or so or about 1.25-1.5" up at the tip. It isn't critical the absolute dimension, just that they are equal. To glue them in place I used some thin cloth hinge material in two places, slotted the wing tip and wing and glued them in place with CA+. The hinge pieces just give a bit of support to the joint. I then used dubro hinge tape on the bottom of the joint. I cut the aileron almost the full width of the wing, about 1 1/4" wide, and cut a 45 degree bevel on the bottom leading edge of the aileron. I then used dubro hinge tape to hinge the surfaces.

For the tail, if you want it full flying, what I did was to use 3m77 spray and laminate a sheet of .015 styrene to the top, and glued on a strip of .04 to the bottom inboard edge. I then drilled a .157 hole at the proper angle from the top of the tail to the inside of the bottom plastic portion. The tube is then inserted and glued. See pictures for details. I drilled out and glued on a dubro micro servo arm to the inboard edge of the aluminum tube before attaching it to the tail surface.

For the fuse, cut out the template including the vertical tail and canopy. You then trace and cut that out. Then cut the template to remove the canopy, vertical tail and a small portion of the tail hook. Trace and make two of these. Third, cut the template to the inner set of lines to give the engine nozzles, and intake splitter plates and make two of these. I then sanded the outer doubler edges to shape and used 3m77 spray to laminate them to the inner doublers. I then rounded the appropriate portions to shape. On one doubler on the inside I inserted and glued a 1/8" carbon rod to provide nose support. I then used 3m-77 spray to laminate it all together. Round all the areas you want to. At this time is is easier to apply paint and panel lines to all pieces.

Cut two .04 styrene disks about 3/4" around and glue them on either side of the tail to support the tail pivot. Mount your motor as desired, leave clearance for the prop. Cut the wing slot and drill the tail with a .157" hole, be sure it is exactly square to the fuse and wing. Glue in a 1/8" ID aluminum tube the correct length to pass through the fuse, leave a little on side.

Cut the fuse for your elevator servo. On mine I had to cut through 4 of the laminations only, not all the way through. The servo is mounted so that the pushrod makes a fairly straight and perpendicular push to the tail surface. You can tack glue the servo in place when happy. You want the servo arm to barely clear the foam so that the wire doesn't stick out from the model, if you don't do this the tip of the control surface will hit the rod and bind in full deflection. My rod had a bit of flex so I used a dubro rod support/standoff that I re-drilled to keep it close to the fuse and straight. Insert a carbon fiber 1/8" rod through the fuse pivot tube the right length to go through both tail surfaces.

You can then install the tail surfaces and pushrod wire and CARFULLY glue them in place. Do this once you are happy with the alignment, verify that surfaces move freely etc.

Insert the wing, get it all aligned in the center and glue it in place. I then mounted two micro control horns on each aileron and bent some music wire pushrods of equal length. I cut a recess in the bottom of the fuse for the aileron servo and mounted it so that it sat nearly flush with the bottom of the fuse and so that the ailerons were aligned.

Mount the rx and esc as far forward on the wing bottom as possible and tape down all wires with dubro hinge tape. I put the battery and ESC on the right of the plane as this helps to counter act torque trim needed. Apply velcro to the right side of the fuse as far forward as needed to make CG. On my plane I needed to add 2 oz of lead weight. I did this by trimming out a portion of the first layer of the right side of the nose and glue in the lead strips, then apply velcro for the battery over this. Alternately you could run a larger heavier battery and add a velcro strap to secure it.

AUW was 15.7 oz for my model. I used model master/testors flat black/flat red, and titanium for the painted areas, and red and blue monokote self adhesive trim for the canopy and red lines. I used thin black sharpie for the panel lines and vinyl letters from staples for the markings. I'm waiting for the 4" stars and bars from Sig mfg to finish it off.

If you use an end connect rx there isn't much sticking down, but you should put some dubro or great planes wing skids on the fuse bottom just to raise it up off the ground a bit to avoid catching anything when landing. My rx was not end connect, and if you used ailerons and had the servos on the bottom you need a little more ground clearance. I just glued on a couple of 6mm plates about 3/4" by 1" wide and long to the bottom of the fuse and mounted the dubro skids into those, that gave me sufficient clearance on landing and they aren't really noticable in flight.

I used about 10 clicks up up trim for the maiden, I reduced throws to 80% elevator and 100% aileron on my spektrum DX-7 after the first flight. Underhand launch is very easy and landings power off were very easy as well.

Here is a where my CG calculation wound up:

http://wingcgcalc.bruder.com.br/en_U...d6=0&sweep6=0&

The build thread here https://www.rcgroups.com/forums/show...t=build+thread shows where a user added pink foam to make the fuse thicker, permanently mounted the horiz tail and just ran elevators and ailerons.

Let me know if you have any questions or comments.

Frank
Last edited by burkefj; Dec 02, 2015 at 10:39 AM.
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Jan 31, 2014, 05:13 PM
Nasir Khan
Quote:
Originally Posted by burkefj
I decided to do another Phantom build, make a few changes to the original and plans. I originally did these because there weren't great simple plans for a phantom at the time. I'm not a big fan of mid mounted engines or box fuses, I'd rather have a slim profile, gives less drag in the air and is quieter. It does require you to mount equipment on the bottom of the wing has the battery mounted on the front side of the nose, but I'm ok with that. Due to the thin profile the wing hits the fuse further forward than on a normal fuse. If desired, you could alter the top view of the wing to include the intake profile and nozzle profile on the rear of the wing so that the top view was more representative, I considered this and decided to leave it clean. If you do this you may need to do some glide tests to confirm CG did not shift as the intake profile will add forward wing area. The wing is not mounted on the bottom, but is in a slot, I did this to give a bit of area under the wing to mount the electronics and not get destroyed on landing.

Maiden video at: http://youtu.be/ve_EA-5susY

For this version I removed the ailerons and just went with differential tail to reduce servo count. I also triple laminated the fuse at the front to give a bit more nose strength, and changed the way I supported the full flying tail.

The plans are just templates with CG marked. There are many ways you can do this plane and a lot of the details are up to you.

Make sure when you print out the plans you do with with no page scaling and borderless, check the marked rulers and be sure nothing was scaled. Tape the wing sheets and fuse sheets together and cut out the parts.

For the wing, it is simple, cut out the parts, round the edges, cut a v groove and glue and tape the spar to the bottom of the fuse. Then cut the wing tips, sand at a shallow angle(10 degrees or so or about 1.25-1.5" up at the tip. It isn't critical the absolute dimension, just that they are equal. To glue them in place I used some thin cloth hinge material in two places, slotted the wing tip and wing and glued them in place with CA+. The hinge pieces just give a bit of support to the joint. I then used dubro hinge tape on the bottom of the joint.

For the tail, if you want it full flying, what I did was to use 3m77 spray and laminate a sheet of .015 styrene to the top, and glued on a strip of .04 to the bottom inboard edge. I then drilled a .157 hole at the proper angle from the top of the tail to the inside of the bottom plastic portion. The tube is then inserted and glued. See pictures for details. I drilled out and glued on a dubro micro servo arm to the inboard edge of the aluminum tube before attaching it to the tail surface.

For the fuse, cut out the template including the vertical tail and canopy. You then trace and cut that out. Then cut the template to remove the canopy, vertical tail and a small portion of the tail hook. Trace and make two of these. Third, cut the template to the inner set of lines to give the engine nozzles, and intake splitter plates and make two of these. I then sanded the outer doubler edges to shape and used 3m77 spray to laminate them to the inner doublers. I then rounded the appropriate portions to shape. On one doubler on the inside I inserted and glued a 1/8" carbon rod to provide nose support. I then used 3m-77 spray to laminate it all together. Round all the areas you want to. At this time is is easier to apply paint and panel lines to all pieces.

Cut two .04 styrene disks about 3/4" around and glue them on either side of the tail to support the tail pivot. Mount your motor as desired, leave clearance for the prop. Cut the wing slot and drill the tail with a 1/8" hole, be sure it is exactly square to the fuse and wing. Glue in a 1/8" carbon rod the correct length to pass through both tail surfaces and the fuse, leave 3/16" on each end extra, since you will slide on some 1/8" aluminum tube pieces to lock the tail surfaces in place.

Cut the fuse for your servos. On mine I had to cut through 4 of the laminations only, not all the way through. I did the same on the other side. the servos are mounted so that the pushrod makes a fairly straight and perpendicular push to the tail surface. You can tack glue the servos in place when happy. You want the servo arms to barely clear the foam so that the wires don't stick out from the model, if you don't do this the tip of the control surface will hit the rod and bind in full deflection. My rods had a bit of flex so I used some dubro rod supports/standoffs that I re-drilled to keep them close to the fuse and straight. You want them as similar as possible to have identical deflection.

You can then install the tail surfaces and pushrod wires and CARFULLY glue a 1/8" long piece of aluminum rod on each end to cap the tail surfaces and keep them in place. Do this once you are happy with the alignment, verify that surfaces move freely etc.

Insert the wing, get it all aligned in the center and glue it in place.

Mount the rx and esc as far forward on the wing as possible and tape down all wires with dubro hinge tape. I put the battery and ESC on the right of the plane as this helps to counter act torque trim needed. Apply velcro to the right side of the fuse as far forward as needed to make CG. On my plane I needed to add 2 oz of lead weight. I did this by trimming out a portion of the first layer of the right side of the nose and glue in the lead strips, then apply velcro for the battery over this. Alternately you could run a larger heavier battery and add a velcro strap to secure it.

AUW was 16 oz for my model. I used model master/testors flat black/flat red, and titanium for the painted areas, and red and blue monokote self adhesive trim for the canopy and red lines. I used thin black sharpie for the panel lines and vinyl letters from staples for the markings. I'm waiting for the 4" stars and bars from Sig mfg to finish it off.

If you use an end connect rx there isn't much sticking down, but you should put some dubro or great planes wing skids on the fuse bottom just to raise it up off the ground a bit to avoid catching anything when landing. My rx was not end connect, and if you used ailerons and had the servos on the bottom you need a little more ground clearance. I just glued on a couple of 6mm plates about 3/4" by 1" wide and long to the bottom of the fuse and mounted the dubro skids into those, that gave me sufficient clearance on landing and they aren't really noticable in flight.

I used about 8 clicks up up trim for the maiden, I reduced throws to 80% elevator and 100% aileron on my spektrum DX-7 after the first flight. Roll is not perfectly axial, wants to drop the nose when inverted, but roll rate for normal yank and bank was perfect, and elevator authority is quite strong. Underhand launch is very easy and landings power off were very easy as well.

Here is a where my CG calculation wound up:

http://wingcgcalc.bruder.com.br/en_U...d6=0&sweep6=0&

The build thread here https://www.rcgroups.com/forums/show...t=build+thread shows where a user added pink foam to make the fuse thicker, permanently mounted the horiz tail and just ran elevators and ailerons.

Let me know if you have any questions or comments.

Frank
Love this model!!

Nas
Mar 31, 2016, 02:30 PM
Registered User
J Bergsmith's Avatar
The fuse is shaping up. Nothing that's really hard to do, just need to think ahead on shaping the fuse as you add the layers.
Apr 20, 2016, 07:35 PM
Registered User
J Bergsmith's Avatar
Making some good progress, almost ready for paint.
Apr 20, 2016, 07:44 PM
Registered User
burkefj's Avatar
Looks good John.

Frank


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