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Jetlegend L39 build

Started by STORM, September 03, 2010, 21:49:32 pm

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STORM

Right guys, just about to start on a new L39 build and could do with some advice as this is my first large jet.
First question, is it best to install robart type hinges by gluing both ends in at the same time and should I reinforce with brass tubing?
Thanks, Gary.

Alex48

September 04, 2010, 07:49:52 am #1 Last Edit: September 04, 2010, 09:29:16 am by Alex48
Hi Gary

Don't glue both ends of the hinge in at the same time, it's too difficult to get them all lined up in one go.  Glue them into the control surface first with the pivot in the correct place. Use brass tube if the hinge is a long way back from former you want to glue the surface to.   You can then glue the control surface on.  Don't forget to grease the hinge pivots before you glue them on.

Check the hinges don't have any play in the pivot, I normally replace with large Robart hinges as these are excellent quality compared with the Chinese stuff.

HTH  
The Little Jet Company
www.facebook.com/TheLittleJetCompany

STORM

Thanks Alex, its the pivot point that's worrying me, I cannot make my mind up exactly where it should be, that's why I considered gluing the lot and by moving the surface hoped they would self align.
  I dont think I will need tube, there is plenty of meaty balsa there.
Take your point on the Robart though.

Vinceyboy

Good luck with the build Gary :af will be watching with interest :)
"Jet flying is strictly on a shoestring"

Alex48

Just make sure the hinge pivot is in the centre of the LE radius of the control surface.  The further away it is from this point the further back the surface will have to be to get the correct movement.  I seem to remember on the JL 39 I did for a friend spending loads of time with a drill and small sanding drum getting the surfaces to fit nicely with the correct amount of throw.

Look forward to your build

Cheers, Alex
The Little Jet Company
www.facebook.com/TheLittleJetCompany

STORM

It'll be good for a laugh Vince, especially as I have lost my B/band and am using my Android!
Alex, I am assuming you had to relieve the trailing edge overlap.

Alex48

A little yes............but no more than any of the other eastern ARF's.  The surfaces did sit further back than I would have liked to bet the required travel. 

You'll enjoy this model, L39's are great to fly. 

Cheers, Alex
The Little Jet Company
www.facebook.com/TheLittleJetCompany

STORM

My goodness it's big, my workshop is a small f bedroom and the nose sticks out the door! I think I'll work on each fuse section seperately. I worked out that the tail hingepoint should be in line with the control rod which means the control surfaces would be back further than I would like but I'll sort it. Got to wait for Robarts now, thanks for advice Alex,
Gary.

Alex48

You should have said, I would have sent some for nout.....
The Little Jet Company
www.facebook.com/TheLittleJetCompany

STORM

Thanks for that mate, I have an account with Ripmax so no problem, just going through closing my model shop down, damn Council tried to double my rent so I will shortly be a man of leisure, 65 in Oct so start drawing pensions!
Gary.

STORM

Alex, I read somewhere that the L39 comes out tail heavy so I also ordered two 5000mah sub c's instead of lead if you get my drift!
Hope it's not too much!!

Alex48

Should be fine, I used large nimh's  in my SM L39 and no lead was needed, I don't remember the JL 39 needing any either.

Got another 35 years left in me  :'( already looking forward to retiring  :)   
The Little Jet Company
www.facebook.com/TheLittleJetCompany

IB



Got another 35 years left in me  :'( already looking forward to retiring  :)   
[/quote]

I retired last Thursday, early I hasten to add, its still got to sink in yet.

Ian B
A womans mind is cleaner than a mans.
She changes it more often.

pylon²

Hi Gary,
Mine has 2 x3300 NIHM and a not used 7.2 volt Nicad up front. Plus my 3000Mah Lipo. Mine C.G is 6" from L.E and flies superb as you have seen.
Can't wait to see yours complete and fly.
I understand my F5 has docked in customs :P
Cheers Richard. :af

Alex48

an F5, cool.....shame you didn't put a wanted add up, Ive got a superb example at the painters atm, should be stunning  :)

Come on then Gary............wheres the pictures  ;)
The Little Jet Company
www.facebook.com/TheLittleJetCompany

STORM

Therein lies a problem Alex. Because I'm in the hard work process of closing the shop and moving stock etc. coupled with switching b/band I'm having to do all internet stuff from my HTC mobile and it ain't easy! Also v little time to build.
Then comes Jetpower (I'm going over to cheer Al on) and treat myself to a couple of days off for a change. Next comes a short wait for the nice pension man to cough up my tax free lump so I can get me my 65th birthday pressie, guess what that's gonna be guys.
Gaz.

selleri

September 08, 2010, 02:16:46 am #16 Last Edit: September 08, 2010, 10:46:21 am by selleri
Quote from: STORM on September 07, 2010, 20:52:32 pm
Next comes a short wait for the nice pension man to cough up my tax free lump so I can get me my 65th birthday pressie, guess what that's gonna be guys.


Loafers and a sweater?     ;D
Sverrir  - Icelandic Volcano Yeti - RCMF Tech Team

STORM

Ha, I just knew you wouldn't be smart enough to guess correctly! ;D

Btw, what's a loffer?

Vinceyboy

Quote from: selleri on September 08, 2010, 02:16:46 am
Loffers and a sweater?     ;D


;D ;D I think he means Loafers Gary, the old name for old mans sued shoes ;)

are you doing your L39 in the same scheme as Richard's? would be nice to see one done a different scheme for a change :af
"Jet flying is strictly on a shoestring"

selleri

Sorry my bad, should have been in bed.   ;)
Sverrir  - Icelandic Volcano Yeti - RCMF Tech Team

STORM

Vince, it's the blue camo, Estonian Air force!

selleri

Hmmm, not too shabby.   :co

[attachimg=#1]

[attachimg=#2]
Sverrir  - Icelandic Volcano Yeti - RCMF Tech Team

Alex48

The Little Jet Company
www.facebook.com/TheLittleJetCompany

STORM

I've got it wrong then, correct camo, wrong markings, red star.

bluescoobydoo

thats a serious amount of up elevator on that l39
jay

STORM

Well, post #25 already and we finally make a start, broadband back on tonight so I can start to do some pics.
First job, install servo for air brakes, pic attached,
Gary.

STORM

Btw that's a lump of lead weight, not a servo!

Pic of thrust tube temporarily nailed down to stop it flopping about and view of air intake.


STORM

General view of back end, note curtains protecting paintwork, this one's gonna use all the space I've got!
Also pic of rear thrust tube support area.

STORM


STORM

I really have to say that this is by far the best chinese kit I have set eyes on, after spending a lot of time inspecting in detail I cannot find much to criticise, one of the main formers that holds the front spar clamps is a bit pissed but if they line up it will not be a problem, I assume that the frame is rough assembled before the brackets are screwed down, if not I am going to have a big dihedral problem.

The glue jounts are all superb (where I can see them), lots of good quality glue nicely filleted with smooth rads, I am becoming a JL fan, we shall see!

STORM

Air brake servo installed and set up, works nicely, beat up old cheapo 13kg MG995 for this job, plenty power, not the end of the world if it packed up, slowed up on Tx servo speed, currently on proportional lever, may mix with something else later.

STORM

Rx set up being used for this Jet with setup battery, main flight power being two sub c 5000mah cells in nose.
This model needs a lot of weight in the front to balance so using these rather than lead. Must change plugs to mpx once cable length to rx is apparent.

STORM

Two very nice 1700 ml tanks as supplied in kit, these are buggers to get in and out so will leave until later. Will probably need another tank somewhere as 3.4 ltrs will not fly for long with the proposed 160 class engine needed.
Also pic of thrust tube exit area.

pylon²

Quote from: STORM on September 11, 2010, 11:27:56 am
Two very nice 1700 ml tanks as supplied in kit, these are buggers to get in and out so will leave until later. Will probably need another tank somewhere as 3.4 ltrs will not fly for long with the proposed 160 class engine needed.


Try ang get another tank in or a bigger single tank, my friend Martin (fb jets agent) had a single 4lt tank in his. Far better for a 160. I fly mine for 6.30 mins max.
Cheers Richard. :af

STORM

Thanks for that Richard, at least its something that can be changed but better to get it right before bolting the front end on.
I may pm you soon to pick your brains, can you tell me one thing, are the flap linkages on the underneath of the wing, reading the rcu forum a lot of folk are coming out of the top using the supplied fairings to cover them? I cannot think why they would want to do that at all.
Got that F5 yet?
Gary.

STORM

Ok, time to look at the tailplane.
Trial fitted to fuse first, perfect fit, good start.
Torque rods lightly vasalined and inserted, horns loose fitted. Two small brass tube bushes made up to space either side of rose joint, bit of binding when moved so some material has now been removed for clearance.

STORM

September 11, 2010, 16:08:48 pm #36 Last Edit: September 11, 2010, 16:13:47 pm by STORM
Cutout taped up for material removal, horns drilled 3mm to take bolt and deburred.
Linkage made up and servo rough positioned for horn slot marking up.

For you pro guys, I am writing this in language that new guys can appreciate so please bear with that!

Quick plug here for the supplier, Jeff Sewell of Zedjet who has been very helpful and is a nice guy to boot, highly recommended and goes out of his way to help.

Jeff had this particular model in stock, I paid a bit extra as the gear, doors and rams were installed, and better than I could have done it, this will obviously save a fair bit of time.

This was intended to be a winter build but after seeing Richard's flying I can't wait any longer, anyway, what use is a retirement present if you can't use it?

STORM

Btw, please remember that this is my first big jet build, wade in and criticise if you want, any suggestions will be appreciated and not frowned on. I need the help!
Can't help thinking that I will miss something that could be critical to an aircraft of this size.

Pat Barnes

Hi Gary

Is that a SAVOX servo? Which flavour mate? I'm guessing it's the 20kg titanium geared chappie.

STORM

Bang on Pat, it's a 1256, 20 kg titanium, coreless, stingfart rip yer nuts off jobbie.

Our American friends use a 25kg Futaba as it's designed to use two ganged servo's if you wish, I opted for one due to the tail heavy situation.

Been using two 12 kg in my Elan tail for trialling and I am impressed with them, Harry will probably chip in and quite rightly say  that even 20 kg is overkill so I think it'll manage the job ok, open to comments on this one!

Gary.