Who Else Wants a 63" Lavochkin La7 kit?

[peter harvey 1]

I have used EMax ES3104 19g mini metal gear servos which just fit, any

small servos will be ok but using metal gears is a must,these were recommended by

Richard and were out of stock, ordered a pair and they came in 7 days from China

cheers

Peter

[peter harvey 1]

Hitec HS-82 mg are the same size but a lot more expensive

Peter

[Bob Cotsford]

Cheers Peter, those look to be only a couple of mm smaller than the HS-225 or Corona 339MGs. Thinking about it I may have a 339 case in the servo spares to try for size.

[Tim Flyer]

My LA7 is coming on quite well now. I’m building it as an “every day sports scale plane as my time (and ability) limits me to that. I started on the fuselage as I haven’t got the retracts yet. I’m hopefully going to use Richards electric models that will be released soon . I’m also waiting for the engine so I can’t do too much at the front either. One question I had before gluing the rear deck / tail , is what I will be using re the elevator connection . I’m not sure whether to just use two connected sleeved rods or use the central control with the horn soldered to elevator joiner. For the central idea I would install a heavy duty snake. I will use a pull pull system for rudder.

[peter harvey 1]

Difficult to use a hidden elevator control, either make a control horn on one elevator or solder a connection to one side of the joining connector, I made an exit on the right side with the control horn supplied fitted to the right elevator. One thing that I did to make lif easier was to install small pieces of copper fuel pipe in each elevator which is used to fit the jointing rod into, this makes it easier to cover the elevators later and fit them individually.

One thing was that the fin was too wide to fit onto the rear deck,(could have been how it had been cut after forming, what I did to make it fit neatly was to cut a slight vee out of the center and using gorilla glue to pull in the sides till they fitted the rear deck, The elevator Sullivan snake went over the crutch plate and the rudder snake went under, this seemed to fit ok and works ok but the elevator control has to be fitted before the rudder/elevator assembly.

carry on the good work

Peter

ps there was some slop in the retracts, the control slot had been milled at 4mm and a 3mm grub screw was used in the sliding assy, what I did was to drill the sliding member (no joke intended) with a 4mm drill, cut some short sections of 4mm piano wire and using these as the guide, nice interference fit, this took the slop out of the unit.

[Tim Flyer]

Hi Peter much appreciated! I found your log very useful indeed and thanks for your kind help. I must admit that I am enjoying building this . It’s the thinking that seems to take the time. 😊. As I haven’t  built a foam decked warbird kit before, I am doing it bit by bit as I don’t want it boxed in making control fitting awkward. 

Edited By Timothy Harris 1 on 23/10/2017 13:39:23

Edited By Timothy Harris 1 on 23/10/2017 13:39:58

[peter harvey 1]

Its as Richard said, these are not production kits, its fun trying to make bits fit as a bit of fettling is needed.

Peter

[Bob Cotsford]

I started the fuselage by attaching the doublers to the sides then switched to the wings rather than clear the bench to lay the fuselage jig down. Bit of a rebel ain't I? I'm about ready to join the panels now, I have to say they were not the quickest of foam wings to put together. The tip blocks needed a lot of planing and sanding! Before shaping them I slotted the TE of the blocks and inset some 1/32" ply to strengthen them where they taper down to next to nothing. I am not using the leading edge root extensions, I couldn't see an easy way to blend them into the wing section so they're gone. I've filled in the retract box with soft balsa block just leaving a retract sized hole and bored 20mm holes for the retract and aileron leads using sharpened copper tube. As I don't like mini servos on this size model I'm using a pair of Corona 339HVs for the ailerons, these are a bit too much of a squeeze in the servo boxes to go in flat so I'll sit them upright in the wing. I'd put the servo boxes in before checking the size, luckily they can still be used just not with the servo flat.

[Tim Flyer]

Well done Bob sounds like you are properly stuck in too. I’m still on the tail section which does require some fiddling and adaptation as above. Luckily I also have plenty of spare wood to adapt it where needed. After the top of fuselage is done , I will take a look at the wings too. I delayed that while I await the retracts as I think I will start with those, as access is easiest as the blog said before the leading edge is glued in . Certainly an enjoyable kit. I can see myself glassing the wings so I won’t have to bother with ply reinforcement of TE. Happy Building 🙂

Edited By Timothy Harris 1 on 24/10/2017 13:21:10

Edited By Timothy Harris 1 on 24/10/2017 13:22:38

Edited By Timothy Harris 1 on 24/10/2017 13:23:30

[peter harvey 1]

Using a lightweight filler you can blend in the wing root sections if you need them, which is what I have donewhith them on it is easier to blend the wing to the fus, but its a bit fiddly. my garage is still full of sawdusr from the wing tips , but my circular electric sander worked miracles after I gave the bread knife back to my wife.

rather than glass the wings I have used tex all over, which is easy to spray if needed

cheers

Peter

[peter harvey 1]

by the way I fitted the aeilerons using furry mylar and then Ironed on a 1" piece of tex to the top surface to seal the gap, this has worked well on my small la7

Peter

[Tim Flyer]

Thanks again Peter, That Solartex looks good! My last few kits I have glassed then hand /rattle painted. I didn’t mind glassing and I’m used to that from boat building, but the painting I hated, and it took ages to get anywhere with the dimpled greasy epoxy surface. It seams I can paint the wood with solarfilm ‘“clear coat” resin that should harden it a bit then sand and Solartex the lot. So I should buy a big roll of white Solartex. 😊😊🙂😊 no painting. Or maybe less! I will probably paint the red bits or just buy a roll of red Solartex. I chose the white winter colour to avoid/ minimise painting.

[peter harvey 1]

I think that that is a wise choice, I also bought a roll of red fablon (also available in other colours) and made the decals from this .Also by cutting it into thin 4mm strips I used this to produce the cockpit framing,as my hand is not steady enough for free hand painting.

Using tex you don't have to harden the wood,but what I did was to mix pva adhesive with about 10% water and wipe down the whole airframe with this and let it dry, I know that tex will adhere to wood however since pva is heat sensitive this just improves the bond.

I have in the past used car paint in cans to spray over tex, this also worked for me .Overall the result was a nice semi matt finish like the real plane as nothing looks worse than a high gloss finish. The Russians were not interested in a nice shiny plane any old paint of approx. the right colour would do, slapped on with a painters brush. The cowling I painted by hand with a broad soft brush and then hand painted with Aerokote semi matt

Peter

[Jon H]

A white model will self weather within minutes as well. If you wanted Tim you could cover it in dark green solartex, then slap some black on it for the black/green camo it would have worn and then go at it with some white over the whole lot. If you use enamel for the black, then water based for the white, you could then go at it as you please to weather it. You could even throw water at it, flick mud on it, anything. Then once satisfied the model is 'ruined' and filthy, fuel proof away and its job done

Incidentally, this method would be super scale as the full size wore a water based white wash over their normal colours for winter operation. Sadly for the russians it was not at all hard wearing and came off easily revealing the normal colours.

Check out these poor Lagg3's!

The Lagg3 was an earlier aircraft and was essentially an La5 with an inline engine. The La7 then was developed from the La5.

[Tim Flyer]

Thanks again chaps for the good tips I’m not now dreading the painting so much 😊

[Bob Cotsford]

How have you handled the underside of the nose forward of the wing? It looks to need about an inch trimming off the lower fuselage side, have you then sheeted between F1 and F2, block filled it or left it open to be covered by the cowl? I don't think I'm too keen on having the front of the wing held on by an unsupported piece of 1/8" ply - or am I missing something on the plan?

[peter harvey 1]

what I have done is to add some bracing between f1 and f2 in my case 1/4 x1/2 spruce, two pieces about 2" apart

and on the edges of the f1 and 2 , these also act as support for the cowling at the bottom, you are right about the trimming of the fus sides, I have also added some fillets between the side ply doublers and f2 and some extra filleting between the top of the crutch and f2, so it is well supported horizontally and at the side and with the bracing at the bottom between f1 and f2, together with the additional 1/4 ply plate behind f1 the complete structure is quite rigid and strong.

leave the final trimming of the sides until you have finished the wing and can present it to the fus, but you also have to ensure it is cut back to fit the cowling

Peter

[peter harvey 1]

Bob , which engine are you going to use, by the way if my explaination above is not clear, I will try to send photos.

in addition to the above, how you fit the wing will also depend on If you are fitting the false leading edge to the wing, I have also removed the point at the front and added a piece of 1/4 ply across the front through which I have drilled the hole for the dowelling

hope this is clear enough

Peter

[Ron Gray]

Pictures please, to help those of us who haven’t started yet!

[peter harvey 1]

HOPE THESE PHOTOS HELP, THERE MUST BE OTHER WAYS TO DO THIS, BUT THIS DOES WORK

PETER

Edited By peter harvey 1 on 29/10/2017 09:47:41

[peter harvey 1]

the ply plate , the base of the fuel tank bay is also epoyied front and back to f1 and f2

peter

[Bob Cotsford]

That looks like the way to go Peter. I found the plan a little confusing (for some reason I was getting a bit OCD about errors and discrepancies on the plan and instructions) where the amount of recess shown on the wing leading edge didn't match what I need on mine. I just need to put a flat on the main LE for the width of the fuselage, not the full cutaway shown. Thinking about it, it obviously needs cutouts in the cowl to clear the LE, or the LE needs notching for the cowl. As I'm not using the LE extensions at this point, I'll cut the cowl as needed.

I've got an OS91 Surpass II-P put aside for this, it's looking a bit grey out so I'll drill the engine mounts and bulkhead this morning after I've caught up on the MotoGP.

I've trimmed 1/4" off the front of the crutch cutout so my F1 will sit 1/4" further back, that will allow me to put some fillets in front of F1 to the fuselage sides for a bit of extra security.

No side or downthrust? I'm a bit of a traditionalist and prefer to get the thrustline right rather than use rudder trim, I'm tempted to add a couple of degrees of sidethrust as that would seem about right for this style of model, and maybe a degree of down too. Have you flown yours yet Peter?

[peter harvey 1]

not yet but on the smaller version I have no down or side thrust and that flies well.The surpass should be grand and easier to install than the laser which requires a larger cutout for the silencer,

on the smaller version I had a 52surpass and I left the silencer all within the cowl, a short piece of silicone tubing fitted over the silencer and this protruded through the cowling and could be removed before taking off the cowling

tubing from just engines

Peter

[Tim Flyer]

Hi chaps . I’m pondering whether to just put the rudder on with a straight hinge line down the back of the tail post or incorporate the diagonal section on the top as per the full size . Obviously cutting and sticking the diagonal bit needs extra work and lining. It might increase rudder effectiveness though?

[Bob Cotsford]

At model scales and with servo driven controls we don't need to worry about the balance effect and the rudder has plenty of area so I think it's down to aesthetics.

What progress - I don't like unsupported wing bolts so I cut the foam out from the roots about 2 1/2" deep and 1 1/2" wide using a hot wire then gorilla glued balsa blocks in to support the wing bolt heads. I've joined the panels but not added the glass tape yet, With the wing in one piece I could offer it up to the fuselage and trim the LE back to get the wing seated with a snug fit around F2. I've slitted the balsa LE caps for the ends of the ply dihedral brace which is again fitted with gorilla glue. That's been setting up overnight so today I'l tidy it up, line up the wing and drill the dowel hole through F2 and the dihedral brace then set about fitting the bolt plate and drilling/tapping for the wing bolts.

When I put the two tailplane sections together I found that it was still 1/2" too narrow needing an extra section adding up front. The main section was cut from 4" sheet with a 1 1/2" additional section whereas the chord needed to be 6". Oops.

I've ordered a couple of HS82MGs from Steve Webb, I might as well at least try to make a proper job of it .