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Who Else Wants a 63" Lavochkin La7 kit?

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Bob Cotsford28/11/2017 12:23:26
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Mine is just a triangle let into the tip block at the rear as there's not much meat left when the block is sanded down level with the wing panel and the aileron. Here's a not very good pic:

Wingtip.jpg

I was thinking of giving the trailing edge 3 or so coats of PolyC to stiffen it up though I do have some 1/64" ply somewhere.  That would be pretty much invisible.  My daughter got me some brown paper from Sainsbury's yesterday, I suspect it's a bit thicker than neccessary being Sainsbury's!

Edited By Bob Cotsford on 28/11/2017 12:27:22

Tim Flyer28/11/2017 13:45:07
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Thanks Peter I’m using Solartex too so i’ll di the same as th back edge is vulnerable as you said.

Tim Flyer28/11/2017 16:06:51
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Thanks too Bob. That’s a good idea too. I appreciate the photo. After I’ve cut the ailerons I will finish the wing tips and will probably do the same thing there too.

Edited By Timothy Harris 1 on 28/11/2017 16:07:20

Ron Gray11/12/2017 11:36:11
1672 forum posts
431 photos

How are the builds coming along guys? I just started mine yesterday, nothing different to report apart from moving F1 back a bit to accommodate the Laser 80.

Bob Cotsford11/12/2017 12:11:38
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8243 forum posts
454 photos

Slowly Ron. All I've done in the last few weeks is to build up the wing fairings and sheet the rear underside.

Plus give the wing and aileron T/Es three coats of Poly-C to stiffen them up.

It's not from lack of opportunity as I've had 6 weeks in front of the telly, just lack of enthusiasm. I finally had the bone pin pulled out of my foot last week and two days later went down with norovirus. Please God, let 2018 be better crying

Ron Gray11/12/2017 12:34:36
1672 forum posts
431 photos

Hell’s bells Bob, that’s not good. As you say, here’s to a better 2018!

Ron Gray11/12/2017 17:03:23
1672 forum posts
431 photos

As a matter of interest I too had the same problem fitting the front veneered foam deck and cut the 2 off 1/2 balsa bearers into wedges as I felt that was easier than cutting the veneer and foam (plus as I've been allowed indoors to work on this - too cold outside, it was far less messy). Running a line through on top of F1 and F2 shows them all at the same height, approx 62mm of the crutch. I also ran a saw blade several times through the foam to make it easier to bend, then have filed the saw cuts with gorilla glue, probably not necessary but it was to hand,

Ron Gray11/12/2017 21:43:13
1672 forum posts
431 photos

Canopy and cowl line up

28ed6618-b010-44c1-aab6-fecb7371cf7b.jpeg

Piers Bowlan11/12/2017 22:42:14
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How many mm did you move F1 back to accommodate your Laser, Ron?

Ron Gray11/12/2017 22:49:14
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431 photos

Forgotten Piers but will measure it tomorrow. F1 sits about 1/8” in front of the crutch cut out now and means that I have wiggle room to get the Laser in without carb or exhaust hitting it and the prop driver also lines up with the front of the cowl.

Ron Gray12/12/2017 07:29:30
1672 forum posts
431 photos

Measured it as 18mm back from the original location of F1. Attached a couple of pics to show it plus I’ve doubled up on the thickness of F1 under the fus crutch, as others have done.

1ea0e622-b9f0-42a5-9b69-f2246495d7be.jpeg

71583fcc-3118-404a-8864-57ea3cec160c.jpeg

 

Edited By Ron Gray on 12/12/2017 07:30:22

Jon - Laser Engines12/12/2017 08:44:54
5186 forum posts
236 photos

look at that lovely hot air exit, no danger of overheating here

Piers Bowlan12/12/2017 09:15:51
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2042 forum posts
53 photos

Excellent Ron, thanks. I was originally planning on using my ASP 91 but Jon will probably be getting an order for a Laser 80 from me in the new year (after the house move!).

Ron Gray12/12/2017 09:40:21
1672 forum posts
431 photos

@ Jon - do you mean the one behind the table?😊

Tim Flyer12/12/2017 09:55:45
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1214 forum posts
231 photos

Get well soon Bob that norovirus is horrid... Good to see the photos of all the various builds. I have started on the wings and cut/ lined the ailerons and done the odd bit of front end reinforcement. Next job is retracts. My oleos are 203 mm so I will need to cut them down too . Then I will be doing the flaps. My 4 Wing servos will all be mounted behind each surface and I won’t be using torque rods. I’m actually tempted to glass fibre/ epoxy the wing when it’s built and just use the Solartex for the body as it seems easiest and I can just add a bit of extra laminate on the trailing edge.....anyway there is still plenty of work before that decision. Happy Building 😊

Jon - Laser Engines12/12/2017 10:28:03
5186 forum posts
236 photos
Posted by Ron Gray on 12/12/2017 09:40:21:

@ Jon - do you mean the one behind the table?😊

Ha! didnt spot that

Bob Cotsford12/12/2017 10:36:03
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8243 forum posts
454 photos
Posted by Jon Harper - Laser Engines on 12/12/2017 08:44:54:

look at that lovely hot air exit, no danger of overheating here

Unfortunately it is throttled a fair bit by the cowl extending back to F2 which means the channel narrows a lot at it's exit, I think a baffle fitting close around the cylinder will still be needed. 3/32" sheet circle fitted in the cowl with an engine shaped cut-out, simple and quick as I've plenty of 3/32" stock. Of course the full size machine had a flap over the exhaust exits so those could be opened up to give more area.

Thanks Tim, I think (fingers crossed) I'm pretty much over it.

I'm drawn to try the brown paper covering but I've also got a box full of Solartex. Yes, it's indecision time again sad

Here's my current itch, the fin tapers from around 5/16" at the top to 1/2" at it's base and the rear fuselage is 5/8" at it's rear, but the rudder stock is only 3/8". The idea of that step down in thickness at the rudder hinge line grates with me so I'm tempted to go for a core and rib structure to match up with the fin's taper. Maybe a 1/2" rudder post, 3/32" core and 3/32" 'ribs' either side. That or sort out some light 1/"2 sheet if I have any.

Edited By Bob Cotsford on 12/12/2017 10:37:47

Bob Cotsford12/12/2017 10:42:30
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8243 forum posts
454 photos

You can see the flaps on this pic:

la7 full size.jpg

You can also see the ribs in the fabric covered rudder and elevators.  More temptaion to go for core and rib control surfaces!

Edited By Bob Cotsford on 12/12/2017 10:44:46

Bob Cotsford12/12/2017 10:58:03
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8243 forum posts
454 photos

nearly forgot - I've also knocked up the oil cooler housing. Looking at drawings it appears to be about 75% of the width of the fuselage on the full-size so I've made mine 3 1/4"*5".

Nose with cowl blocks in place:

cowl mountings.jpg

and the wing fairings:

wing fairing.jpg

Tim Flyer12/12/2017 11:04:48
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1214 forum posts
231 photos

Hi Bob pleased are on the mend ...That core and rib will look better but I just used the standard build. I agreed with you re baffles. The cowl throttles the exit vent . I plan to use a front balsa blanking wall at the front of the cowl and cut a hole in it directly in front of the engine and make baffles to direct the air onto the fins. That’s also why I blocked off the cut out in F1 that I made for the silencer and carb. This will make sure no air ( or oil!) is driven behind F1 but is just forced through the side vent. I might also make a slight flaired tab (semi scale😉 outif thin Aluminium on the cowl air exit to help suck air out. There is a small tab I can see in the full size...

Edited By Timothy Harris 1 on 12/12/2017 11:43:08

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