Maj. Woody's Fei Bao L-39
02-20-2008, 10:49 PM
#54
RE: Maj. Woody's Fei Bao L-39
Finished the fin and rudder tonight. Looking under the cover you can see the internal structure used to mount the servo. The arrangement looks taylor made for a flat wing type servo. I decided to use a JR 3421 (75 Oz @ 6V) so I cut the tabs off of the plywood structure. Next I fit one of Tamjets EZ Servo Mounts that is made for the Jr 3421. I then added some Dave Brown Carbon Fiber tape to either side of the servo mount. The tape is actually hair like and turns to near steel when saturated with thin CA. This really stiffened things up and I would highly recommend it. The fin skin is not strong enough to handle the flight loads if not properly reinforced. Cut a slot in the cover for your servo arm. I had to add a washer under each corner of the servo cover to raise the cover so it was flush with the fin. The rudder hinges are glued to the rudder at the factory but not the fin. It was necessary to remove about 1/8" of material from the TE of the fin to get the proper rudder travel. Cut a slot and glue in the control horn. The rudder is then glued to the fin, linkage added and then the linkage was painted.
Dom
Dom
02-21-2008, 07:32 PM
#56
RE: Maj. Woody's Fei Bao L-39
I will be adding more fuel for sure. I won't know exactly what I'll do till I do it. I am leaning toward a 24 oz tank above the stock tank.
I had to remove about 1/8" from the trailing edges of the stabs to get proper elevator travel. I needed to clean up the ends of the elevators too. They were crooked and the resulting gap between the the elevator and tip is larger than I would like. The hinges are factory glued to the elevator but not the stab. Be careful when gluing in the hinges. The first hinge hole is drilled through to the cavity where the CF spar passes. To keep this area from filling with glue, I used a FG pushrod in the spar hole to act as a dam while gluing.
Dom
I had to remove about 1/8" from the trailing edges of the stabs to get proper elevator travel. I needed to clean up the ends of the elevators too. They were crooked and the resulting gap between the the elevator and tip is larger than I would like. The hinges are factory glued to the elevator but not the stab. Be careful when gluing in the hinges. The first hinge hole is drilled through to the cavity where the CF spar passes. To keep this area from filling with glue, I used a FG pushrod in the spar hole to act as a dam while gluing.
Dom
02-22-2008, 03:03 PM
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RE: Maj. Woody's Fei Bao L-39
good job Dom
I flew mine last weekend, with P-70
I had a flutter in the rudder fin, I couldn't get time to even to trim it. i had to land quickly. I had a JR 3301 servo in the rudder, by the way, my flap was set to 30mm for landing and it couldn't slow it down for landing!!
i guess I'm going to cut that flap out and do a new hinges so i can get more flap down.
Salah
I flew mine last weekend, with P-70
I had a flutter in the rudder fin, I couldn't get time to even to trim it. i had to land quickly. I had a JR 3301 servo in the rudder, by the way, my flap was set to 30mm for landing and it couldn't slow it down for landing!!
i guess I'm going to cut that flap out and do a new hinges so i can get more flap down.
Salah
02-22-2008, 05:53 PM
#60
RE: Maj. Woody's Fei Bao L-39
Hi Guys.
Yes there is a bit of modifying (tweaking) to be done. But this has been the case with every brand jet I have "built"....Jetlegend, Fei Bao, Tamjets and Skymaster.
Must be the camera angle. The gear looks and feels beefy to me.
Easy Tiger...who flew one of the early prototypes had flutter as well. I have reinforced my servo mount with CF and have a very solid hinge job. I also have a JR 3421 that has 75oz of tork at 6V. I use this servo for aileron, elevator and rudder on several of my jets with excellent results. I think that the 3301 only has 55oz of tork. Anyway I hope that this is not a design flaw. I may take another look at my rudder servo and add even more reinforcement if needed. As far as the flap travel you are limited to about 30mm due to the live hinging. I am using a Hitec 645MG on flaps that is rated at 133oz @ 6V and can just get 30mm. I am not a fan of the live hinging. My aileron servos are working hard as well. I hope they have the guts under flight loads. I have 95oz servos for aileron and elevators. The are futaba digitals but I can't remember the number right now.
Dom
Yes there is a bit of modifying (tweaking) to be done. But this has been the case with every brand jet I have "built"....Jetlegend, Fei Bao, Tamjets and Skymaster.
Must be the camera angle. The gear looks and feels beefy to me.
Easy Tiger...who flew one of the early prototypes had flutter as well. I have reinforced my servo mount with CF and have a very solid hinge job. I also have a JR 3421 that has 75oz of tork at 6V. I use this servo for aileron, elevator and rudder on several of my jets with excellent results. I think that the 3301 only has 55oz of tork. Anyway I hope that this is not a design flaw. I may take another look at my rudder servo and add even more reinforcement if needed. As far as the flap travel you are limited to about 30mm due to the live hinging. I am using a Hitec 645MG on flaps that is rated at 133oz @ 6V and can just get 30mm. I am not a fan of the live hinging. My aileron servos are working hard as well. I hope they have the guts under flight loads. I have 95oz servos for aileron and elevators. The are futaba digitals but I can't remember the number right now.
Dom
02-23-2008, 07:38 AM
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RE: Maj. Woody's Fei Bao L-39
by the way, i didn't use the hinges that come with the kit (I have bad experience with it) I used robart hinges and I doubled the control horn in Aileron and Rudder so there is no play. but still got flutter in the rudder, maybe of plastic servo arm or the mount. don't know but i will do some reinforcement there.
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02-23-2008, 10:39 AM
#63
RE: Maj. Woody's Fei Bao L-39
Does not look like a linkage issues. I noticed that the plywood servo mount is rather thin and flexes quite a bit. I did not use this. You can add some blocks between the plywood frame and fin sheeting to stiffen things up. I would also switch to a stronger servo of at least 75oz.
Dom
Dom
02-23-2008, 05:54 PM
#64
RE: Maj. Woody's Fei Bao L-39
I finished the tail section today.
First I fit the stabs to the fuse. You can see I had to trim a bit of the fuse for elevator clearance. This is because I trimmed the TE of the stabs earlier for proper elevator travel. Next I ruffed up the stabs, fuse and CF spar in preparation for glue. I glued the stabs in place with two operations. First the CF spar and left stab, then the right stab. This gave me the time I needed to position everything and clean up before the epoxy set up. Next was the installation of the control horn on the elevator shaft. The factory has the set screw on the top of the arm instead of the bottom. This required me to drill a hole in the top of the fuse to pass a allen wrench. I could have drilled and tapped a new set screw location on the arm but did not want to. The kit comes with CF push rods that are small in diameter and quite stiff. You are supposed to use the threaded rods and clevis but for the life of me don't know how. There are no ends supplied with the push rods leading me to believe you are to epoxy these into the push rods. I don't trust that method so I did things differently. I took a length of threaded rod and after measuring and cutting the rod and CF push rod to length I silver soldered on a washer and clevis to one side of the rod. The rod is then passed through the CF tube and secured at the other end with a 4-40 nut and red locktite. When you tighten this nut it draws down on the CF tube and the arrangement is very strong. Next is a small 4-40 nut and clevis. Finally I bolted the fin into place. I checked my servo set up again in the fin and am very satisfied with it. It is very very stiff so I don't anticipate any flutter issues. I think I am going to work on the cockpit next since this will take some time and I will need it completed on order to layout my equipment and determine the C.G.
Dom
First I fit the stabs to the fuse. You can see I had to trim a bit of the fuse for elevator clearance. This is because I trimmed the TE of the stabs earlier for proper elevator travel. Next I ruffed up the stabs, fuse and CF spar in preparation for glue. I glued the stabs in place with two operations. First the CF spar and left stab, then the right stab. This gave me the time I needed to position everything and clean up before the epoxy set up. Next was the installation of the control horn on the elevator shaft. The factory has the set screw on the top of the arm instead of the bottom. This required me to drill a hole in the top of the fuse to pass a allen wrench. I could have drilled and tapped a new set screw location on the arm but did not want to. The kit comes with CF push rods that are small in diameter and quite stiff. You are supposed to use the threaded rods and clevis but for the life of me don't know how. There are no ends supplied with the push rods leading me to believe you are to epoxy these into the push rods. I don't trust that method so I did things differently. I took a length of threaded rod and after measuring and cutting the rod and CF push rod to length I silver soldered on a washer and clevis to one side of the rod. The rod is then passed through the CF tube and secured at the other end with a 4-40 nut and red locktite. When you tighten this nut it draws down on the CF tube and the arrangement is very strong. Next is a small 4-40 nut and clevis. Finally I bolted the fin into place. I checked my servo set up again in the fin and am very satisfied with it. It is very very stiff so I don't anticipate any flutter issues. I think I am going to work on the cockpit next since this will take some time and I will need it completed on order to layout my equipment and determine the C.G.
Dom
02-23-2008, 09:52 PM
#66
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RE: Maj. Woody's Fei Bao L-39
MW, I agree with you, just JB welding a wire in the end of the c/f shaft is a little scarry. I did the same thing you did however, added sheet zap on the threaded rod and ended up gluing the threaded rod inside the c/f pushrod. For the rudder servo mount I put bass wood blocks, custom sized to fit under mount tabs, full length to match wood outline. Also put a wood spacer under the servo so it matches the tabs in height. No rocking now. Thanks for your inputs. Heard from Wagner where the bypasses are? WHMC
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02-23-2008, 11:26 PM
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RE: Maj. Woody's Fei Bao L-39
ORIGINAL: MaJ. Woody
No word on the bypass yet. Wagner will come through.........He's a great guy!!
Dom
No word on the bypass yet. Wagner will come through.........He's a great guy!!
Dom
02-24-2008, 01:23 AM
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RE: Maj. Woody's Fei Bao L-39
When you tighten this nut it draws down on the CF tube and the arrangement is very strong.
02-24-2008, 04:51 PM
#74
RE: Maj. Woody's Fei Bao L-39
Been working on my "fun Scale" cockpit. This thing is not intended to represent the actual airplane but to fill the void under the canopy. As long as the cockpit looks somewhat realistic I'm ok with it.
I cut the tabs off the fuse under the main hatch. I also removed enough material to the rear of the hatch to easily insert or remove the fuel tank. The front cockpit tub is from my old T-45. The rear tub is not used. I decided to leave the rear deck flat giving me more room underneath for equipment. With both tubs in place it is very tight and the rear tub hits the fuel tank brass tubing. The T-45 tubs are actually about 1/8" shallower than the L-39 tubs so it will be worse with the stock set up. The rear deck was made from plastic and then painted. I also painted (gray) the canopy frame inside the canopy and fuse. I removed both cross members that are part of the fiberglass canopy frame. My canopy arrived with a small crack in the frame and clear plastic. The fuse has a crack in the same place. I noticed Easy Tigers prototype had the same cracks. The glue job on the canopy could have been neater. There is glue above the frame/canopy line that looks unappealing. The instrument panels were made from plastic and instruments that I bought from Hobby Lobby (same as on my Panther). I will have it all assembled in the next couple of days and then post some pics. I felt that the included glare shield filled up too much of the front windscreen (about 95%). That is what prompted me to start fitting the T-45 cockpit. I was able to mount the T-45 glare shield much lower and now the windscreen is about 50% full.
Dom
I cut the tabs off the fuse under the main hatch. I also removed enough material to the rear of the hatch to easily insert or remove the fuel tank. The front cockpit tub is from my old T-45. The rear tub is not used. I decided to leave the rear deck flat giving me more room underneath for equipment. With both tubs in place it is very tight and the rear tub hits the fuel tank brass tubing. The T-45 tubs are actually about 1/8" shallower than the L-39 tubs so it will be worse with the stock set up. The rear deck was made from plastic and then painted. I also painted (gray) the canopy frame inside the canopy and fuse. I removed both cross members that are part of the fiberglass canopy frame. My canopy arrived with a small crack in the frame and clear plastic. The fuse has a crack in the same place. I noticed Easy Tigers prototype had the same cracks. The glue job on the canopy could have been neater. There is glue above the frame/canopy line that looks unappealing. The instrument panels were made from plastic and instruments that I bought from Hobby Lobby (same as on my Panther). I will have it all assembled in the next couple of days and then post some pics. I felt that the included glare shield filled up too much of the front windscreen (about 95%). That is what prompted me to start fitting the T-45 cockpit. I was able to mount the T-45 glare shield much lower and now the windscreen is about 50% full.
Dom
02-24-2008, 04:54 PM
#75
RE: Maj. Woody's Fei Bao L-39
I am a bit concerned about the pilots for my L-39. "They" missed the approach to the runway at Winamac and cleaned the gear out of my T-45 last year. I hope their skills have improved befor they fly my new L-39!!
Dom
Dom