F-16XL ARF by Global Knight Models from Global Jet Club
#51
My Feedback: (2)
Paul - all due respect its not as bad as you make it out to be, saying it's unsafe is stretch. I'm all about safety and doing what needs to be done, I don't take shortcuts nor go cheap, but until you own a XL, pictures don't tell everything, my XL appears to have more reinforcement than Gary's, why that is only Global can answer that. If it was unsafe I don't think Ali would be flying it, we discussed it at FL jets and it was never brought up in the conversation.
Is it perfect? no way, but tell me a jet that comes out of China that is today. I've been around the block seen it all just like yourself, but if it was unsafe as your suggesting this XL in the video would of not flown today, the pilot who flew it is even more conservative than myself. I agree improvements need to be made and I will make those improvements, today we observed no flexing or stress in the wing or inside the fuse. I wish RC jet manufacture's could all build to the same standards as you did during your amazing Buccaneer build, but unfortunately they don't for reasons you know, but please know this, if we felt that our XL's were unsafe to fly in anyway, they would NEVER fly period. I don't play the Vegas bet if my jet going to come apart in flight or fail. If there is an issue it stays ground until its 100% fixed or replaced.
I have no doubt Mike and Global would do whatever it takes to make us safe and happy that's been my experience so far. As I said I respect your opinion, your amazing builder and I wish you all the success on the next build, but don't assume were our here flying by the seat of our pants flying unsafe F16XL's.
Is it perfect? no way, but tell me a jet that comes out of China that is today. I've been around the block seen it all just like yourself, but if it was unsafe as your suggesting this XL in the video would of not flown today, the pilot who flew it is even more conservative than myself. I agree improvements need to be made and I will make those improvements, today we observed no flexing or stress in the wing or inside the fuse. I wish RC jet manufacture's could all build to the same standards as you did during your amazing Buccaneer build, but unfortunately they don't for reasons you know, but please know this, if we felt that our XL's were unsafe to fly in anyway, they would NEVER fly period. I don't play the Vegas bet if my jet going to come apart in flight or fail. If there is an issue it stays ground until its 100% fixed or replaced.
I have no doubt Mike and Global would do whatever it takes to make us safe and happy that's been my experience so far. As I said I respect your opinion, your amazing builder and I wish you all the success on the next build, but don't assume were our here flying by the seat of our pants flying unsafe F16XL's.
Last edited by F900; 03-27-2021 at 07:43 PM.
#53
My Feedback: (57)
Gary,
Your inspection confirmed my suspicion based on your first post about the wing joiner. If that were me, I would not fly it without significant reinforcement at the outer end of the tube. As shown, I would class it as very unsafe.
Ideally the factory would install an outer 1/8" ply rib that was mechanically interlocked with the bulkheads which would also support the outer end of the wing joiner tube, thereby providing an outboard mechanical up/ down load-bearing capability to complement and react the wing bending loads against the existing inner clamp block.
As that cannot be easily retro fitted, maybe consider adding a hard-wood support block above and below the tube (full-length) that completely fills in the area between the tube and the upper and lower fuselage skins, and then glassing that in with additional carbon. Also, add another mini-bulkhead on the opposite side of the tube to the existing one to help tie the upper and lower fuselage skins together.
Paul
Your inspection confirmed my suspicion based on your first post about the wing joiner. If that were me, I would not fly it without significant reinforcement at the outer end of the tube. As shown, I would class it as very unsafe.
Ideally the factory would install an outer 1/8" ply rib that was mechanically interlocked with the bulkheads which would also support the outer end of the wing joiner tube, thereby providing an outboard mechanical up/ down load-bearing capability to complement and react the wing bending loads against the existing inner clamp block.
As that cannot be easily retro fitted, maybe consider adding a hard-wood support block above and below the tube (full-length) that completely fills in the area between the tube and the upper and lower fuselage skins, and then glassing that in with additional carbon. Also, add another mini-bulkhead on the opposite side of the tube to the existing one to help tie the upper and lower fuselage skins together.
Paul
David
#54
Thread Starter
My Feedback: (20)
...consider adding a hard-wood support block above and below the tube (full-length) that completely fills in the area between the tube and the upper and lower fuselage skins, and then glassing that in with additional carbon. Also, add another mini-bulkhead on the opposite side of the tube to the existing one to help tie the upper and lower fuselage skins together. Paul
On the opposite side of the former I will place a wood or carbon spar from the outside fuse edge under the rectangular hole to the turbine rail. This will add strength to the narrow part of the former and help transfer the loads to the wide part of the former but still allow access to the servo wires.
A little extra work but will be a little stronger.
#55
Thread Starter
My Feedback: (20)
Fuel tan version 2
Keith did his CAD magic and sent me a revised fuel tank design that is in two halves, front and back. It is slightly smaller but easier to mount and fill with out the two raised parts as before. It is estimated to hold 40-45 oz. This draft front section is black and white because the printer ran out of black filament and all I had left was white. I was able to change spools and and save the print. The recess area on the front bottom is to clear the fuse joining blind nut and bolt.
Inside view has some ribs to make the front wall stiffer.
The back half is printing and I will get to it tomorrow.
Fits better that the first version
I changed the bottom blind nut from the front fuse section to the rear so the tank can be installed before the fuse sections are joined together. Access to the bolt is through the nose gear door.
Tank recess clears the blind nut and bolt
Dry fit of rudder servo in base of fin
Aileron servo pocket opened up and the pre wired extension has no plug. Also looks like there is not much surface area to attach the hatch with screws.
Keith did his CAD magic and sent me a revised fuel tank design that is in two halves, front and back. It is slightly smaller but easier to mount and fill with out the two raised parts as before. It is estimated to hold 40-45 oz. This draft front section is black and white because the printer ran out of black filament and all I had left was white. I was able to change spools and and save the print. The recess area on the front bottom is to clear the fuse joining blind nut and bolt.
Inside view has some ribs to make the front wall stiffer.
The back half is printing and I will get to it tomorrow.
Fits better that the first version
I changed the bottom blind nut from the front fuse section to the rear so the tank can be installed before the fuse sections are joined together. Access to the bolt is through the nose gear door.
Tank recess clears the blind nut and bolt
Dry fit of rudder servo in base of fin
Aileron servo pocket opened up and the pre wired extension has no plug. Also looks like there is not much surface area to attach the hatch with screws.
Last edited by Viper1GJ; 03-28-2021 at 06:19 PM.
#56
Thread Starter
My Feedback: (20)
Nose gear steering
Nose gear assembly is removed by 4 bolts. Retract motor wire is snaked up to cockpit area so it has to be pulled out
Servo is mounted to the outside of the frame. The smooth aluminum servo case against the smooth aluminum frame made it impossible to keep the servo in place with just the 3mm bolts in the wide holes on the servo mounts. I made some bolt centering bushings from a nylon tube from the scrap box. Used a tubing cutter to slice about 2mm off and place on bolt. Coated bolts with Vibra Tite and mounted the servo. I applied Vibra Tite to the ball link bolts also.
The steering arm is 18mm. I had an old SWB arm and the 2nd hole was 18mm. I cut it to fit and adjusted the ball links.
The frame depth is 22 mm from servo spline. With the ball link attached it extends below the frame a little so I will have to grind a shallow relief in the nose gear mounting tray to clear the servo arm ball link.
View from inside frame.
The steering has a unique tiller to the gear strut. It is a ball link that allows the steering arm to move in the ball joint when retracted.
A drop of BVM dry lube to all the joints.
Nose gear assembly is removed by 4 bolts. Retract motor wire is snaked up to cockpit area so it has to be pulled out
Servo is mounted to the outside of the frame. The smooth aluminum servo case against the smooth aluminum frame made it impossible to keep the servo in place with just the 3mm bolts in the wide holes on the servo mounts. I made some bolt centering bushings from a nylon tube from the scrap box. Used a tubing cutter to slice about 2mm off and place on bolt. Coated bolts with Vibra Tite and mounted the servo. I applied Vibra Tite to the ball link bolts also.
The steering arm is 18mm. I had an old SWB arm and the 2nd hole was 18mm. I cut it to fit and adjusted the ball links.
The frame depth is 22 mm from servo spline. With the ball link attached it extends below the frame a little so I will have to grind a shallow relief in the nose gear mounting tray to clear the servo arm ball link.
View from inside frame.
The steering has a unique tiller to the gear strut. It is a ball link that allows the steering arm to move in the ball joint when retracted.
A drop of BVM dry lube to all the joints.
Last edited by Viper1GJ; 03-29-2021 at 03:39 PM.
#57
Thread Starter
My Feedback: (20)
Operational PETG tank off printer and cleaned up.
Skirt cut off and edges deburred
Rounded corners are lightly sanded smooth
Rear half cleaned up same way.
Joint came out perfect. No sanding required on the lap joint. Credit to Keith's good design.
Internal ribs give front and rear walls good stiffness.
Ready for dry fit
Fits good. Now for mounting and hold down system.
Skirt cut off and edges deburred
Rounded corners are lightly sanded smooth
Rear half cleaned up same way.
Joint came out perfect. No sanding required on the lap joint. Credit to Keith's good design.
Internal ribs give front and rear walls good stiffness.
Ready for dry fit
Fits good. Now for mounting and hold down system.
#59
Thread Starter
My Feedback: (20)
I'm not an engineer but here's what I would do to modify it.
Ideally, I would design it so that the wing tube sleeves are in the center of the formers and directly transfer wing loads to the former. The clamp would be centered in the former. However, this may be too much of a redesign so here is what I would recommend using the existing molds and hardware.
I would place a 3mm plywood rib on the outside of the wing root between the two main formers and have the outside ends of the wing tubes key into the rib. You could put lightening holes in the rib to save some weight. This would tie the outside end of the wing tubes to the loadbearing formers and spread the wing loads into the formers and the fuse skins. If the rib made the tanks not fit then I would make the tanks slightly smaller or just notch the turbine rails to fit. (Either way you need another gas tank because most guys that will fly this thing will want it.)
Then I would make very sure there were no gaps between the wing tube sleeves and the formers. This is to make sure the load path from the wing tube sleeve is transferred to the former over the entire length of the sleeve. (In mine there are gaps between the wing tube sleeves and the formers that you can see looking up from the bottom. The spacer between the sleeve and the former is not wide enough to fill the gap and there was no glue there to fill the gap in places.)
Then I would run carbon tow up over the top on both sides of the wing tube formers. This would be just like the joint on the main landing gear sub former. This would resist compression on the upper part of the fuse and better support the load path under positive G.
After this I would wrap carbon cloth over the former and sleeve joint like now except I would make sure the carbon gets tucked under the sleeve on the bottom and contacts the former and lower fuse skin. Then I would apply two additional pieces of carbon cloth. One at the outer end of the tube sleeve to connect the sleeve to the top and bottom fuse skins. The other would wrap over the top of the sleeve through the rectangular hole and down the other side of the former and contact the lower fuse skin on the opposite side of the former. This would unitize the entire joint between the former, sleeve, outer tube end to rib, and top and bottom fuse skins.
Just my two cents worth. I would love to here what Paul recommends. He really good at it and he helped me figure out some of this stuff on my F-105 project.
Having said this, it’s been a long time since I’ve been as excited about a jet model as this one. I’ve got F-16 baggage from my past life, and this is truly a unique airplane. It will match my flying style perfectly!
Gary
Last edited by Viper1GJ; 03-30-2021 at 07:57 AM.
#60
Thread Starter
My Feedback: (20)
3D print clean up process
I got ask about the clean up process from 3D printing. Here is what my coach Keith advised for the PETG tanks we have been using on foamy turbine conversions. The printer lays down skirt of plastic first around the item printed to help it stick to the bed during the printing process.
The skirt is waste material and must be removed.
When using PLA it just snaps off but with PETG I found it has to be cut off. I use curved Lexion cutting scissors
Skirt removed
The printer prints support material where ever it needs to hold up a recessed area.
The supports snap out easily with some needle nose pliers
Supports out
Next the edges are cleaned up using a deburring knife tool Really handy tool makes it very easy
t
Light sanding to smooth out the rounded edges
All done. The next process is similar to Kevlar or glass tanks except for coating the inside with a light coat of laminating epoxy to seal any pin possible holes. I clean the surfaces with alcohol or acetone to remove any oils or dirt first. Install plumbing, scuff sand all mating surfaces and epoxy together with hysol. Then glass the seam and finish with a light coat of laminating epoxy on outside to seal any possible pin holes from the print.
I got ask about the clean up process from 3D printing. Here is what my coach Keith advised for the PETG tanks we have been using on foamy turbine conversions. The printer lays down skirt of plastic first around the item printed to help it stick to the bed during the printing process.
The skirt is waste material and must be removed.
When using PLA it just snaps off but with PETG I found it has to be cut off. I use curved Lexion cutting scissors
Skirt removed
The printer prints support material where ever it needs to hold up a recessed area.
The supports snap out easily with some needle nose pliers
Supports out
Next the edges are cleaned up using a deburring knife tool Really handy tool makes it very easy
t
Light sanding to smooth out the rounded edges
All done. The next process is similar to Kevlar or glass tanks except for coating the inside with a light coat of laminating epoxy to seal any pin possible holes. I clean the surfaces with alcohol or acetone to remove any oils or dirt first. Install plumbing, scuff sand all mating surfaces and epoxy together with hysol. Then glass the seam and finish with a light coat of laminating epoxy on outside to seal any possible pin holes from the print.
The following users liked this post:
Dansy (03-30-2021)
#61
Gary, with prints that have so much surface area like you do there, the skirt is not needed and can be removed in your slicing software. Actually in the slicer I use (Cura), what you have there is actually a brim, not a skirt. Like the brim of a hat, attached all the way around. A skirt would just be a printed outline around the base, but not attached to the model. Typically just useful to make sure your filament is laying down well to help you decide if you need to cancel/adjust. Anyway, as you found the brim is easy enough to remove, but again it's really not necessary when your model already has so much surface area to adhere to the print bed on its own.
I'm loving the idea of the 3d printed tanks though, very cool. I'm good with the printer but know nothing of the design, I wish I had the design skills like your buddy Keith does.
I'm loving the idea of the 3d printed tanks though, very cool. I'm good with the printer but know nothing of the design, I wish I had the design skills like your buddy Keith does.
Last edited by Auburn02; 03-30-2021 at 06:54 AM.
#62
My Feedback: (4)
I only have structural courses in building design so nothing more formal.. so yes talking out or by backside here... . but that single clamp is really trying to doing a lot of work. The moment of movement is really long so its best at holding the wing in, but not much else. think of waving a broomstick around by the very end. lift is going to pull "up" on that carbon wrapped tube - that is what is really carrying the load here. I would add a second clamp near the wing root to better distribute the load, or former or something..or increase the size of that clamp to be 1" of engagement with the spar tube... there are two and with that big root, there is room to distribute the load. It is probably safe to fly, but I would be checking those carbon wrapped tubes before and after every day of flying... Paging Bob Parks!
#63
What are those tests they have to do in some places in Europe? Support the plane by the wings and load it up with something like 10-20x the model's weight? I wonder how the stock configuration would stand up to that, or if that's even a good test in the first place. It always looks impressive anyway.
#64
My Feedback: (2)
Hi Mike,
I'm not an engineer but here's what I would do to modify it.
Ideally, I would design it so that the wing tube sleeves are in the center of the formers and directly transfer wing loads to the former. The clamp would be centered in the former. However, this may be too much of a redesign so here is what I would recommend using the existing molds and hardware.
I would place a 3mm plywood rib on the outside of the wing root between the two main formers and have the outside ends of the wing tubes key into the rib. You could put lightening holes in the rib to save some weight. This would tie the outside end of the wing tubes to the loadbearing formers and spread the wing loads into the formers and the fuse skins. If the rib made the tanks not fit then I would make the tanks slightly smaller or just notch the turbine rails to fit. (Either way you need another gas tank because most guys that will fly this thing will want it.)
Then I would make very sure there were no gaps between the wing tube sleeves and the formers. This is to make sure the load path from the wing tube sleeve is transferred to the former over the entire length of the sleeve. (In mine there are gaps between the wing tube sleeves and the formers that you can see looking up from the bottom. The spacer between the sleeve and the former is not wide enough to fill the gap and there was no glue there to fill the gap in places.)
Then I would run carbon tow up over the top on both sides of the wing tube formers. This would be just like the joint on the main landing gear sub former. This would resist compression on the upper part of the fuse and better support the load path under positive G.
After this I would wrap carbon cloth over the former and sleeve joint like now except I would make sure the carbon gets tucked under the sleeve on the bottom and contacts the former and lower fuse skin. Then I would apply two additional pieces of carbon cloth. One at the outer end of the tube sleeve to connect the sleeve to the top and bottom fuse skins. The other would wrap over the top of the sleeve through the rectangular hole and down the other side of the former and contact the lower fuse skin on the opposite side of the former. This would unitize the entire joint between the former, sleeve, outer tube end to rib, and top and bottom fuse skins.
Just my two cents worth. I would love to here what Paul recommends. He really good at it and he helped me figure out some of this stuff on my F-105 project.
Gary
I'm not an engineer but here's what I would do to modify it.
Ideally, I would design it so that the wing tube sleeves are in the center of the formers and directly transfer wing loads to the former. The clamp would be centered in the former. However, this may be too much of a redesign so here is what I would recommend using the existing molds and hardware.
I would place a 3mm plywood rib on the outside of the wing root between the two main formers and have the outside ends of the wing tubes key into the rib. You could put lightening holes in the rib to save some weight. This would tie the outside end of the wing tubes to the loadbearing formers and spread the wing loads into the formers and the fuse skins. If the rib made the tanks not fit then I would make the tanks slightly smaller or just notch the turbine rails to fit. (Either way you need another gas tank because most guys that will fly this thing will want it.)
Then I would make very sure there were no gaps between the wing tube sleeves and the formers. This is to make sure the load path from the wing tube sleeve is transferred to the former over the entire length of the sleeve. (In mine there are gaps between the wing tube sleeves and the formers that you can see looking up from the bottom. The spacer between the sleeve and the former is not wide enough to fill the gap and there was no glue there to fill the gap in places.)
Then I would run carbon tow up over the top on both sides of the wing tube formers. This would be just like the joint on the main landing gear sub former. This would resist compression on the upper part of the fuse and better support the load path under positive G.
After this I would wrap carbon cloth over the former and sleeve joint like now except I would make sure the carbon gets tucked under the sleeve on the bottom and contacts the former and lower fuse skin. Then I would apply two additional pieces of carbon cloth. One at the outer end of the tube sleeve to connect the sleeve to the top and bottom fuse skins. The other would wrap over the top of the sleeve through the rectangular hole and down the other side of the former and contact the lower fuse skin on the opposite side of the former. This would unitize the entire joint between the former, sleeve, outer tube end to rib, and top and bottom fuse skins.
Just my two cents worth. I would love to here what Paul recommends. He really good at it and he helped me figure out some of this stuff on my F-105 project.
Gary
I agree with Gary's comments about an outer rib from 3mm ply as shown by your yellow sketch on the photo. Make sure that the fuselage mounted wing joiner tube fully penetrates the new outer rib and is bonded to it well. This will react the wing bending load against the existing inner clamp and spread it into the fuselage. Consider running the new rib full length to do the same with the forward joiner also. That way the 2 frames and ribs would be come a self-jigging structure. Lightening holes in the rib would be beneficial too away from the joiner areas.
I also recommend interlocking the frames into the new outboard rib so that the wing load gets transferred mechanically and not just reliant on a glue joint. Below is a similar area from my Buccaneer showing the interlocking between the outer rib and one of the frames.
I don't think there is a need to wrap the tube with carbon to the frame between the new outer rib and the existing clamp - that area isn't doing anything much in terms of load transfer anyway. Given the design of the clamp, there probably has to be a gap between the tube and the frame. Filling the gap won't do much from a structural perspective apart from fixing the tube in place. All the strength and structural integrity is with the clamp and the new outer rib.
I'm really impressed with Mike's willingness to update the design quickly based on comments and observations. The last thing we need is another FEJ episode with jets that look great but suddenly start to fall apart. Maybe an advisory to all existing customers that maybe don't visit RCU would be beneficial also.
Paul
#66
Thread Starter
My Feedback: (20)
Gary, with prints that have so much surface area like you do there, the skirt is not needed and can be removed in your slicing software. Actually in the slicer I use (Cura), what you have there is actually a brim, not a skirt. Like the brim of a hat, attached all the way around. A skirt would just be a printed outline around the base, but not attached to the model. Typically just useful to make sure your filament is laying down well to help you decide if you need to cancel/adjust. Anyway, as you found the brim is easy enough to remove, but again it's really not necessary when your model already has so mucseh surface area to adhere to the print bed on its own.
I'm loving the idea of the 3d printed tanks though, very cool. I'm good with the printer but know nothing of the design, I wish I had the design skills like your buddy Keith does.
I'm loving the idea of the 3d printed tanks though, very cool. I'm good with the printer but know nothing of the design, I wish I had the design skills like your buddy Keith does.
I still have no clue how to draw something in CAD. I've used several files from Thingiverse and Keith has drawn me a few items like this tank. Hopefully I'll start learning some CAD basics soon and can make my own stuff.
Thanks again for the info,
Gary
#73
Thread Starter
My Feedback: (20)
Aileron servo install
The ailerons use a direct drive system with a machined pin on the servo arm driving the aileron in a slot in the aileron root. I found that a 15mm horn was what was required to allow the servo to fit over the pre marked mounting holes. I used blue Locktite to attach the pin to the servo horn
Servo horn ready. I also use a blob of goop on the servo screw to keep it from backing out in use. Don't ask how I learned to do that!
The aileron root has a slot. There is no plastic bearing in the slot. As best as I can tell the slot is in plywood. This is a little concerning and the wear in the slot will have to be watched over time to make sure no slop develops.
The pin goes in the slot to drive the aileron.
The plywood aileron mounting plate is glued to the inside top of the wing skin. I found that it required a 15mm horn to allow the servo to fit he marked holes. A 20mm horn was tried but that pushed the servo forward 5 mm and put the servo mounting holes over the forward edge of the mounting board
Once I got the holes located I CA hardened the holes with thin CA.
The servo location with the 15mm horn allows the pin to fit into the pre cut curved slot
The supplied servo mounting screws were too long and would punch through the top wing skin. I did not have any shorter screws so I used 6-32 nuts for spacers.
The aileron is hinged by CF pins into pre drilled holes in the root of the aileron bay and the wing tip missile rail.
I taped the missile rail on to test the aileron throws
Down aileron throw ok (wing is up side down)
Up aileron ok.
The aileron hatch cover did not have any wood mounts to put screws in. I did not want to put the screws on the very edge of the hatch into the fiberglass so I cut some plywood corner gussets
Corner gussets install. Screw holes will be drilled later.
The ailerons use a direct drive system with a machined pin on the servo arm driving the aileron in a slot in the aileron root. I found that a 15mm horn was what was required to allow the servo to fit over the pre marked mounting holes. I used blue Locktite to attach the pin to the servo horn
Servo horn ready. I also use a blob of goop on the servo screw to keep it from backing out in use. Don't ask how I learned to do that!
The aileron root has a slot. There is no plastic bearing in the slot. As best as I can tell the slot is in plywood. This is a little concerning and the wear in the slot will have to be watched over time to make sure no slop develops.
The pin goes in the slot to drive the aileron.
The plywood aileron mounting plate is glued to the inside top of the wing skin. I found that it required a 15mm horn to allow the servo to fit he marked holes. A 20mm horn was tried but that pushed the servo forward 5 mm and put the servo mounting holes over the forward edge of the mounting board
Once I got the holes located I CA hardened the holes with thin CA.
The servo location with the 15mm horn allows the pin to fit into the pre cut curved slot
The supplied servo mounting screws were too long and would punch through the top wing skin. I did not have any shorter screws so I used 6-32 nuts for spacers.
The aileron is hinged by CF pins into pre drilled holes in the root of the aileron bay and the wing tip missile rail.
I taped the missile rail on to test the aileron throws
Down aileron throw ok (wing is up side down)
Up aileron ok.
The aileron hatch cover did not have any wood mounts to put screws in. I did not want to put the screws on the very edge of the hatch into the fiberglass so I cut some plywood corner gussets
Corner gussets install. Screw holes will be drilled later.