Topic: Jetlegend L39 build

Slight engineering problem, the supplied ally servo mounts are a little too long for a Savox, they foul the servo cable so I had to shorten and shape one of them to clear.

Slot in servo panel cut out. note the mandatory Blueberry muffin to keep me going, partner is working all day and I have no time or inclination to cook!

Kit supplied plywood u mounts also have to be laminated to get the height correct and modified to fit servo neatly, no biggie.

Hi Gary, this is how Skymaster secure the servos.... This was similar to what I was trying to explain earlier

Cheers, Alex

See what you mean Alex.

The servo cover plate is quite substantial with a 3mm support/mounting plate that is supported at the sides by ribs and front and rear by spars so I think it will be sufficient, as it's now done I'll see how it copes with a bit of force applied.
May look at the flaps with that system though.

Pic attached, also last job this evening is the u frame epoxied to the top plate all hidden below weights!

Nice chat today, thanks for your advice,

Gary.

Hi Gary,
My linkages/hinges are underneath the wing. My F5 arrives on Monday I believe
flew my L39 twice yesterday at Tibenham, Lozza has got a cracking picture apparantly .
Progress looks good on yours      I would definately put a bigger tank in as there is room especially if using a 160 like mine.

Richard.

Thanks Richard, I'll start hunting around and see what I can find, it would be handy to have one big tank rather than the headache of plumbing three tanks and a uat, I've got that system on my Javelin and F16 and the two main tanks never seem so fill up evenly before fuel comes screaming out of the vent!

Bet you're looking forward to your new toy!
Gary.

I will have a word with Martin, I think he may have the jig for the cradle he made to house a 4lt parafin bottle. Just 1 feed and fill/vent etc.

Yes can't wait will maybe do a build thread.
Richard.

Air brake servo installed and set up, works nicely, beat up old cheapo 13kg MG995 for this job, ...

I'd suggest replacing that one, do a quick google on them, might be okay but what I've seen in use and read about, I wouldn't trust them myself.   

I will have a word with Martin, I think he may have the jig for the cradle he made to house a 4lt parafin bottle. Just 1 feed and fill/vent etc.

Yes can't wait will maybe do a build thread.
Richard.

Hi Richard
I am using the 2 original main tanks and another 500ml on top of the 2 it was a drain buster bottel and it works perfect no problems I have a Simjet 3000 in mine and do get over 10 min out of this setup.

all the best
Andy

Hi Sverrir, I recently had one pack up on my Elan flaps.

My fault entirely as I had heard that they do not like being y leaded and I proved it.

I have been using them successfully on nose steering without any problems at all.

If it packed up in the L39 it would not be a disaster on air brakes and I am inquisitive to see how it performs.

Richard, don't do a build thread, it doubles the building time!

Gary.

Duly noted!!!

If it packed up in the L39 it would not be a disaster on air brakes and I am inquisitive to see how it performs.

True(unless it explodes     ) and the PB should stop any feedback from it.   

Bloody hell, what got you up so early, pre flight nerves?

Bloody hell, what got you up so early, pre flight nerves?

pre flight nerves? what have you been keeping secret Sverrir? have you got back in the seat with a new model?

I'm going up to JMA Honington today, hopefully get my XL flown at long last

Mind you, I like Hangar Queens, they last longer

Have a good day Vince, I'm giving Hon a miss, getting ready for Jet Power next week! 

Bloody hell, what got you up so early, pre flight nerves?

lol, I wish, nothing new aquired yet.   

Got good news on Friday though, well good'ish, as expected nothing was wrong with the 160 but the ECU, pump and led board was bust, damn you salt water!   

Sverrer, I used to race offshore model powerboats from 2005-2007, gas variety, big'uns so I know all about damn salt water.
If water got inside the radio box (supposed to be waterproof) that was the end of anything electrical/electronic.
Even stripping everything down and spraying with special switch cleaner all would seem ok for a bit but sooner or later kissed out.
As I was going for the British Championship I never took the chance and replaced everything.
Worth it though, runner up 05 and 06, finally became champ in 2007.
Had four great flights with the Elan again today, now 71 in all, they seemed to clock up really quickly.
Just glued in some Robart hinges in L39 elevators, I hate the job!!
Gonna leave it another ten minutes and then check alignment, position etc, wait for the epoxy to almost set and trial fit to tailplane, timings got to be spot on.
I guess I hate the job because if you get it wrong it's major surgery as you know. Fingers crossed,  
Gary.

For those of you interested got a little bit more done today.
After glue setting overnight the tailplane servo has been screwed to the mounting plate and fits the hole nicely after a little fettling to clear the servo mounting brackets.
Small hole made for the servo lead exit offset to one side so as to stay as far away from the thrust tube as possible, this will have to be heat protected along with the extension lead before final assembly.
Then went flying for a bit of fun with the Elan and a little more done this evening.

Decided tonight to tackle the dreaded Robart hinge job. Did a trial dry fit and measured the natural pivot centres and all seemed to match up probably because the self centred.
Took a measurement of the pivot pins to elevator l/edge and after fettling the slots for the torque rod took the plunge and mixed up some Devcon 2 ton epoxy, thickened it with some micro balloons to simulate Hysol properties (good tip that btw, much cheaper than buying expensive Hysol and just as strong and effective)
A dab of silicon oil on the hinge pins and away we go.
Liberal dose of glue down the holes and a smear on the hinges and it all looks good.
Watched a bit of telly with the elevators on the table and patiently waited for the glue to almost set, about 55 minutes, finalised the line up of the hinges, left for aniother 15 minutes and fitted them to the tailplane.
At this point the glue was strong enough to stop the hinges moving but still left me with a little time for forced adjustment should it be neccessary and also allowed the hinges to self align without binding.
These are being allowed to set overnight.

Doing a great job Gary enjoying reading the build

I didn't get to go flying again had to put my caravan back up the storage place, as I live on a main road, it had been parked outside my house since the Nats with my neighbour's spare car in front, his son has borrowed the car so my tow hook was unprotected, although I have a hitch lock, it's still risky, so felt safer moving it So it's still a Hangar Queen

Thanks Vince, it's nice to know that at least one person is following the build.
I sometimes think I'm the only one that reads it and maybe I'm doing something wrong or wasting my time! 
Gary.

Keep it going Gary, I'm enjoying reading it in a basic language that I can understand:af  also Sverrir's got nothing else better to do at the moment

Times are hard at the moment, and I think the jet scene has cooled off a little due to peoples finances, you can see it when you look at the Bumfa adds, nothing is hardly moving

I need a 120 for my F15 but that will have to wait

Same situation Vince, I need a 160 turbine for the L39, it will have to wait a bit!
Ok, I'll keep it going then, just for you! 

Harry will probably chip in and quite rightly say  that even 20 kg is overkill

Correct!

I knew that would happen lol! 

Just happened to have some in stock Harry. 

I have yet to see a model crash due to excessive servo power.
 On the other hand.. Ask me how many models I have seen fail due to a servo not being able to drive a control surface under load (in flight) and I will struggle to keep count. 
 

Thanks Al, I agree entirely, I do understand what Harry is saying though, I tested this Savox thing with a meter last night, it draws 0.01 amp on standby and when I really lean on it it only goes up to 1 amp which rather suprised me!
Gary.
p.s. love the F100, looking forward to seeing it this weekend.

Keep it going Gary, I'm enjoying reading it in a basic language that I can understand:af  also Sverrir's got nothing else better to do at the moment

Besides enjoying the F-15's that are flying past my office window this month!     Keep it coming mate!

Maybe I should get one for the P160 and celebrate the past...    

Thanks Sverrir, nice link! 

I enjoy following along with these builds.......keep it going, I'm enjoying myself 

No taking the p**s then!   

OK...

















 

Back to the build then. The plan today was to finally install the elevators to the tailplane.
I checked the line up and debated whether to wait and get some brass tube as the hinges have a gap of about 11mm with no support at the tail t/edge.

At this point I noticed a MAJOR engineering cockup. The substantial 8mm torque arms that slot into an ally bracket in the elevators had the grub screw fixing holes way too far back. Pics show that on one side particlarly the grub screws are only half hanging on to the machined torque arm square!
This is a very serious error and could have resulted in a disaster.
 

The fix?? Could drill and tap more holes closer to the ele l/edge or why not epoxy them in, after all they should not need to ever be replaced.
Rather than run the risk of mis drilling the holes and ruining the surfaces I will probably glue them permanently.
Right, Alex, should I get some tubing in to support these hinges better??

At this point I decided to can the tail and have a look at the port wing and make a start on that. I have this habit of when hitting a brick wall start looking for another! 

As we are now suspicious of torque rods I got the wing tank out also which has an ingenious aileron drive setup using the same type of system.

Look at this gorgious wheel hanging off the wing, ain't it loverly!

The aileron servo sits in the wing tank with a link to the torque rod which is again clamped to an ally bracket in each aileron. A dry fit proved that these rods line up perfectly with the slots but the whole system hangs on two 3mm grub srews which if they came loose??

Of course the hinges if correctly glued will stop them disconnecting but won't stop them swiveling out of position resulting in loss of control. Worrying.

I noticed on RCU some guys installed a support bearing to support the rod, I'm thinking about that.

There are times when I wonder if the Chinese ever made just one kit that went together with zero problems but I guess that's what makes us Jet fanatics, everything has to be just right and GUARANTEED to work.

To set this servo arrangment up it obviously requires that the tank be mated with the wing panel and, yes, you've guessed it, another headache.

The two ally bars glued into the tanks fit into a matching pair of brass tubes and are then secured with small bolts. The tank would not look at assembling and investigation showed that one of the ally rods was not glued exactly square, it was about .03mm out. 

The rod would not bend without tearing the glue joint out so I dremeled the t/edge of it to give it a lead at the outer end and with a bit of a grunt and some vasaline (where have I heard that before?) I managed to work it into position

Whilst I waited for some laminated u brackets to dry I thought I may as well have a crack at installing the flap and aileron extensions. With a bit of flexi wire and masking tape I managed to do that job.

Next was to line up and glue the bracket at 90 degrees to the hinge line and generally add more weight in the form of epoxy to strengthen the whole servo plate so it could go nowhere!

Now the really funny bit, the servo fixing holes in the bracket needed a dab of cyno to harden the holes, a useful technique when working with soft crappy Chinese light-ply.

As I was applying it vertically downwards I managed to glue my fingers together after 40 odd years of modelling it's the first time ever, just shows we all make mistakes but no glue got on to the model and that's what's important!

doh...

If it were me I'd reinforce the hinges, probably overkill but I've never had a model die of flutter yet...