1/7th F-14D Scratch build thread

[Thomas_W]

	Quote: Originally Posted by dylanc11
	Its working for me.

they are now, and shouldn't have any more issues for atleast a year.... but haven't been for the past day or so.

[Thomas_W]

Well lets see.. not much progress with anything on this trip, as it has been busier than expected. But i have gotten the majority of the wing sweep gearbox drawn up. I found a source for the gears for a decent price, and all of the box parts (5 in total) are the same material, and then their is the steel output shaft and worm spacer... Should be fairly simple items to have machined up. I had debated on doing a 1 piece gearbox but b/c of the fact of all the steps needed on the output shaft (b/c of the need to go from metric to standard) and on the worm spacer (gotta fit a 10mm hole onto a 3.2mm shaft) it had to be made up in sections.. So here's a picture:



Dimensions are about 2 1/2" tall, 1 5/8" deep and 1 1/4" wide. Fairly small in dimensions amazingly... Should have an output RPM of about 2800RPM with no load drawing about 2amps.

According to solidworks the assembly should weight 135grams (4.75 ounces) not including the motor, bearings, hardware and worm gear. I'm guessing the overall weight should come in about 3/4 of a pound with all of those items installed and the assembly hardware.

[Thomas_W]

Got some more CAD drawings done.. the wing sweep actuator parts are 99% complete! I just have to go over the box assembly dimensions and adjust them for the 10:1 gear ratio to be sure the gears will clear the gearbox parts, and adjust the spacer and motor mounts for the new motor shaft size and mounting bolts.

With this setup as shown in the CAD program, it is essentially 100% complete, minus assembly hardware, bearings and motor. What you see is about 50 hours of work and weights 2 3/4 pounds. So with hardware, motor and bearings, i expect it to weight right at 3lbs. Not bad, considering the lead screw components and rod-end attachment at the wing are rated to withstand 4,000 pounds of force before anything will fail!!!! So basically the assembly hardware and motor will fail before the sweep mechanism will. The down side... their is probably $600-800 in machine work to make the parts for everything. Luckily the lead screws, gears, universal joints, hardware, bearings, motor and a few other little things are just regular "items" and fairly simple and in-expensive.

So here's some pictures:

Lead-screw to wing adapter (this is the "female" part of the jack-screw assembly and is what actually sweeps the wing in and out).


And the Entire assembly in one..

[Thomas_W]

Been doing some more cad work. here's the final parts for the horizontal stab and servo mount and the stab control arm. Overall weight is 6 ounces minus 2 bearings and some hardware, so i'm going to guess at 7.5 ounces fully assembled and ready for installation, then add 2.5 ounces for a 8711 servo you get 10 ounces per assembly or 20 ounces total. which comes out to 1.25 pounds. slightly heavier than i was hoping, but their will be alot more "stuff" infront of it to offset this weight.

[Thomas_W]

Decided to do a bit more research on the wing bearings and ended up finding a 3/4" ID x 1 7/8" OD tapered ball bearing that will work much better than the pair of radial bearings and pair of thrust bearing i had originally planned to use. mostly b/c its less parts and comes out lighter. there will be a machined aluminum holder out of 6061 aluminum that the taper bearing cuts will press into. Your probably wondering what the V notch's in the bearing holder are for. this is so the carbon cloth and epoxy will have something to "bite" into to help attach the holder to the wing skins. There will also be a 1/4" end-grain balsa wing spar that will be laminated with carbon cloth on both sides that will be glued to the wing skins and then 2 layers of carbon cloth that will wrap around the bearing holder and extend down the wing spar 9" and have a roll over onto the wing skins by 2" to tie everything together.

This may sound heavy, but for the wings, i'd rather sacrifice a pound between the 2 wings for the extra piece of mind knowing that the attachment points will not fail. With this, the last of the CAD stuff for the wing pivot and sweep assemblies and the stab mounts are DONE! All thats left to do now, is draw up the parts for the spoilers and leading edge slats and i can call the cad stuff complete. So here's a picture.

[LarryV]

Thomas,

Is 1/4" end-grain enough for the shear web? Typically a little more than that is used in high load applications like this, especially at the root.

[Thomas_W]

	Quote: Originally Posted by LarryV
	Thomas, Is 1/4" end-grain enough for the shear web? Typically a little more than that is used in high load applications like this, especially at the root.

larry, actually i'm planning on taking 1/4" x 6" sheet balsa and cutting the sheet perpendicular to the grain direction and then edge gluing the sheets together than a layer of 6oz 3k carbon. I forgot to mention their will be an additional 1/4"/carbon sandwhich the first 16" of the wing from the root outward as well, so you there will be 16" of 3/4" carbon/balsa wing spar (each wing panel is only 35" long)

[Thomas_W]

Been doing some thinkin on how to hinge the full span spoilers ( no dinky 1 panel spoilers on this F-14). Having looked at a some photo's of the real thing, the hinge method is the same as what we use for offset door hinges on the models. So i drew up a hinge set and did an animation of what i needed. The drawing is pretty much complete, i just have to adjust the "pivot" holes to the proper size (planning to use Eight - 2mm bolts so the spoiler panels are fully removable and replaceable if anything were to happen). Each hinge composes of 3 parts, one part will be epoxied to the actual spoiler panel between the outer skin and the inner "detail" panel in a jig that i will come up with once the spoiler molds are done. The other 2 will be hysol'd and glassed to the wing panel. There will be a total of Eight hinge assemblies per wing of which their will be 24 hinge "parts". Total deflection is 55 degrees in the fully extended position which is exactly the same as the real thing... The wing parts of the hinge are .060" thick and the spoiler part is .125" thick. Im currently debating on if these will be milled from carbon fiber or G-10 sheeting.

Here's the photo and the animation of the hinge to 65*


http://smg.photobucket.com/albums/v4...yanimation.flv

[2robinhood]

This is one cool build.

I found this interesting and I thought that maybe you guys following this thread would like it also.
I am not trying to jump it, just a cool video.

YouTube - Broadcast Yourself.

[3Dguy]

[Thomas_W]

should have an update tonight.... not a whole lot done though

[3Dguy]

Cool, thanks. I just wanted an excuse to use that " bump" smiley...