Parkflyers International Expertimental: Grumman F-14D Tomcat G1R-S

Discussion in 'Scratchbuilding!' started by bimoadiprakoso, Mar 25, 2018.

  1. bimoadiprakoso

    bimoadiprakoso Top Gun

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    The Grumman F-14 Tomcat is an American supersonic, twin-engine, two-seat, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experimental (VFX) program after the collapse of the F-111B project. The F-14 was the first of the American teen-series fighters, which were designed incorporating air combat experience against MiG fighters during the Vietnam War.

    The F-14 first flew in December 1970 and made its first deployment in 1974 with the U.S. Navy aboard USS Enterprise (CVN-65), replacing the McDonnell Douglas F-4 Phantom II. The F-14 served as the U.S. Navy's primary maritime air superiority fighter, fleet defense interceptor, and tactical aerial reconnaissance platform into the 1990s. The Low Altitude Navigation and Targeting Infrared for Night (LANTIRN) pod system were added in the 1990s and the Tomcat began performing precision ground-attack missions.

    In the 1980s F-14s were used as land-based interceptors by the Islamic Republic of Iran Air Force during the Iran–Iraq War, where they saw combat against Iraqi warplanes. Iranian F-14s reportedly shot down at least 160 Iraqi aircraft during the war, while only 12 to 16 Tomcats were lost; at least half of these losses were due to accidents.

    The Tomcat was retired from the U.S. Navy's active fleet on 22 September 2006, having been supplanted by the Boeing F/A-18E/F Super Hornet. The F-14 remains in service with the Iranian Air Force, having been exported to Iran in 1976.

    With some ideas running around inside our heads, along with the curiosity on how to build a fully working score-n-fold swinging wing, we decided to start this project as a learning based project with hope that if this project works we could make it available to scratchbuilders just like our other parkjet designs.

    We started to design it with some criteria in hand:
    1. Have to be easy to build, still with score-n-fold design.
    2. Need to have no additional materials other than commonly used in score-n-fold designs

    Along the way, we addressed some challenges in the way that we need to answer those under the same criteria above:
    1. Simple swinging wing construction.
    2. Full plane control with elevons only when the wings don't have any aileron in order to simplify the built.
    3. Calculate the CG right under 2 different conditions: expanded and collapsed wings.

    We finally came up with the base design of the F-14D, using Rhinoceros 6.0 and OpenFOAM Computational Fluid Dynamics with Paraview that digitally met our requirements.

    upload_2018-3-26_9-5-2.png

    The design consists of some aerodynamics compensations in order to make the CG location in both wing states close to each other, as well as rods weight calculation inside the wing to balance the CG correctly. So, using 3mm carbon rods for the wing is crucial.

    The swinging wing mechanism is pretty straight forward: the wing rotation axis would place the same a the servo arm axis, with the help of popsicle sticks in holding the wings. However, Wildthing, jimbosflyin and me had different approaches in order to show some possibilities to construct this F-14's swinging wings.

    It is definitely an interesting experimental project for us as we will learn something out of it.

    We strongly recommend to use these particular parts for the swinging wing mechanism:
    1. External 6V 3A BEC.
    2. JX Servo PS-1171MG 17g Metal Gear Analog Servo, that could deliver 3.5kg of torque when using 6volt BEC.

    We tried with Emax ES08MA ver 2 sevo on ground tests and it failed to perform. So after looking around for some strong servos with similar dimensions, we picked JX PS-1171MG as the choice of servo for this swinging wing.

    Stay tuned as updates will follow :)

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    Last edited: Mar 25, 2018
  2. Looks neat Bimo! Looking forward for the sweep mechanism too. I built one from Shumate’s design and it flew well. His recommended servo did not work so well so after much testing this one worked out the best:

    https://hobbyking.com/en_us/turnigytm-380mg-micro-mg-servo-3-6kg-0-15sec-15-6g.html?___store=en_us

    Works well with regular 5V bec by providing enough torque but with 6V its even better!

    With many servos that I tried, the problem wont be when sweeping the wings back but getting them back out...
    I almost always had to slow down the plane to bring it to a glide and pull the wings out. But with the TGY-380MG servo it works great without any issues!

    Just a suggestion... looking forward to your build
     
  3. Hi Malukk,
    Thanks for the lead, I missed that one, it's right in their for torque. For the wings trying to keep it simple they will be direct drive, the servo will be the pivot .

    Cheers
    Jeff
     
  4. bimoadiprakoso

    bimoadiprakoso Top Gun

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    Hi malukk! :) Really appreciate the suggestion my friend.

    The specs looks better for alternative. My problem was that I didn't have much time to play around and look for a series of alternatives. However, your recommendation is top notch :cool:

    According to CFD, the required torque at 1" from the servo axis is around 1.8-2kg. So, any servo above 2.5kg should be okay.

    I just noticed that I had a typo in the title :D That happened when my fingers were typing without a brain leading them :p

    Parkflyers International Parkjets

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  5. FlyteTime

    FlyteTime Ace Pilot

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    Taking it to the next level PI crew! That's what I'm talking about. Don't you just love a challenge? Between all your great minds I'm sure it's gonna turn out to be another winner. Good luck guys. Looking forward to it.

    P.S. I'm currently building a Craig Clarkstone Panavia Tornado swing wing rear mounted pusher. It has no airfoil wing like yours will, and it has a fairly complicated swing wing mechanism. I'll post up when I get a little further along on it.
     
  6. Start a thread on it, looking forward to watching your build. :)
     
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  7. FlyteTime

    FlyteTime Ace Pilot

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    Will do Jeff...
     
  8. F1wanabe

    F1wanabe Administrator

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    Have you seen our F14 Bimo? That combo of servo activated and simple swing wing is mutually exclusive. Also, the elevons have zero authority when wings are full out and very little when mid sweep. With rear prop you'll may need artificially large elevons to compensate for their ineffectiveness. I really liked Dave's idea of the up-only actuating aileron, but then again, there goes the simplicity.

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    Last edited: Mar 26, 2018
  9. Construction of the wings. Going a little different then Bimo's original plan of how to mount the servo arm to the wing. I figured for a strong area to disperse the force on the foam plus give me a fair friction free surface I cut out 2 plywood discs. 1 190mm out of 1/64" and a 50mm out of 3/16 plywood and glued then together. The X servo arm has a strong place to be mounted to.

    2018_0314_175418_004.JPG 2018_0314_183900_002.JPG 2018_0314_190509_001.JPG 2018_0314_190523_002.JPG 2018_0315_063842_001.JPG
     
  10. TacticalFlight

    TacticalFlight Ace Pilot

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    Lets hope the wing mech.opens and closes in fight and is improved from whats been done already.This aircraft with swing arms has been done many times with little succsess in flight.Like the Romans, build on whats been done already.Not really your design but an improvement on what's been done already.Impress me.......lets see something different....and what works.
     
  11. We aim to please. :)
     
  12. TacticalFlight

    TacticalFlight Ace Pilot

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    I like that......lets hope so.I think Jeff should be able to do it.You have the drive and build ambition to do so.......lets see it happen.
     
  13. I lack patience though and that sometimes is my downfall. :D :D
     
  14. jimbosflyin

    jimbosflyin Top Gun

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    Start painting yet ?:cool:
     
  15. Nope, no ideas yet. ;)
     
  16. More wing construction. Added a 1/2 triangular balsa to the leading edge and sanded round, trailing edge is tapered down to a nice point . Servo arm is squared off and centered. Wing has two 6mm strips in it and with the balsa LE is really nice and firm. No epoxy used , just UHU Por and 3M spray adhesive, hopefully it doesn't bite me in the butt.

    2018_0315_185119_002.JPG 2018_0315_185129_003.JPG 2018_0315_185138_004.JPG 2018_0316_065535_001.JPG 2018_0316_070901_001.JPG
     
  17. It appears as though you are planning on using one servo per wing for movement, Jeff?

    The blend of foam and balsa looks very good!
     
  18. You are correct, this way we eliminate all that extra control rods and linkage setups that just screw up. This is why the servos have to be strong because they won't have any geared down leverage, gain on one end and give up some on the other. We have experimented with a lot of different materials to try to give us a friction free surface for the wings to pivot on.

    Jim and I have bounced a million ideas off of each other, Bimo has been super busy but he has done his magic with numerous tests on the computers to come up with a total plane that is going to fly great with one cg point , he has all that fancy software that measures everything, beyond my brain. :D

    The wing itself really turned out ridged, I am afraid I will break it before it bends. ;)

    Cheers
    Jeff
     
  19. Neat! I was going to say have you experimented anything with 3d printed setup yet?
    When I was building mine, I really wanted to make a jig where you have a small ball bearing (from a broken motor or so) embedded in the wing to allow it for super smooth sweeps. In which case, using one servo would work out great and will be fairly accurate on either side given that its 3d printed.

    Kinda like this in the video below but the bearing mounted in a 3d printed piece (6mm thick) which is then glued flush to the wing and a simple CF rod of appropriate thickness could be used as a pivot shaft:



    you get the idea... I could help out some in trying to come up with it but then not everyone would be able to do/get the 3d printed jig I suppose... so if you want to anybody to be able to build this plane then I think your setup should work out great! The balsa piece does add some stiffness... On my Shumate F-14, I used a 5.5mm CF rod that went thru the wing which was also plenty stiff and it actually integrated with the "pivot ply" so that it would not flex up and bind in flight even when you do loops and sweep at the same time...

     
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