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Who Else Wants a 63" Lavochkin La7 kit?


jrman
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The horn balance (the bit ahead of the hinge line) should be the work of a moment to make. If you then cover the rudder in solartex it will be easy to get it round the corners. I wuld go for it as its not much work, enhances the look of the model and slightly reduces the load on the servo.

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Thanks for replies. I will go for the rudder horn balance as mentioned then . I think it will look better. My other ARTFs warbirds have it so that will be ok. I wasn’t going to bother last night and planed the front of the rudder but it’s easy to ad a bit of wood in. Regarding the tail section as Bob said it is too short I added some wood also to fill a half inch gap between the two sections and also had to compress the sides of the fin moulding as it was a bit wide. I still can’t start my wings as no retracts, and can’t do more front end until I get the engine and mount it. Happy building 🙂.

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Hurray. Thanks John . It will be my third of your 80s . I do think they are a nice sized engine. I can’t wait to get to work on the engine bay. I don’t see any problem at all with fitting. To be honest that’s my favourite bit of plane building. I never like to put the tail on before the engine as the rear of the plane is fragile. This plane is fun as I have a free hand in reinforcement and adding buts up front to make it nice and strong. I will also post up photos in a few weeks when the engine is in. I might use a couple of degrees of side thrust as Bob said . I won’t put any down thrust in though.

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Just a quick one Jon, I've recently started a new facebook page called R/C balsa aicraft kit manufacturers and supplies. It's to encourage manufacturers to get themselves better aquainted with the modelflying public due to an increase in model building interest. I still get people asking about traditional kit suppliers and thought I'd do something about it but the suppliers need to get on there and promote themselves. I thought that Richard also might benefit. It's all free and can only help. There are already over 300 members.

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Posted by Daren Graham - Cambria Funfighters on 09/11/2017 10:27:28:

Just a quick one Jon, I've recently started a new facebook page called R/C balsa aicraft kit manufacturers and supplies. It's to encourage manufacturers to get themselves better aquainted with the modelflying public due to an increase in model building interest. I still get people asking about traditional kit suppliers and thought I'd do something about it but the suppliers need to get on there and promote themselves. I thought that Richard also might benefit. It's all free and can only help. There are already over 300 members.

Nice idea. Once our factory move is completed (by January i hope) we are looking at setting up a facebook page to see if it helps us in any way. To be honest i think it will, as long as i dont spend all day deleting spam posts.

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Did anyone else have this issue?

Last night I finished fitting F1 and a tank support so of course I had to try the cowl inplace. At first i thought that somehow I'd built in loads of upthrust. After running around like headless chicken for 5 minutes and expending my stock of expletives I calmed down and started checking a few measurements against the plan. Much to my relief the problem was in the line of the top deck which sloped up towards the cockpit by 1/4". I never thought to check the dimensions when fitting the foam deck, I guess these are really prototype kits with the inevitable issues that involves.

I took the easy option and slid a blade between the crutch and the 1/2" square beams then took a 1/4" wedge of the bottom of the beams. Gluing thess backdown onto the deck pulled the top of F2 back a shade but I was intending to plate the front of the former anyway in order to seal off the interior.

img_20171112_121126074[1].jpg

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I had thought about using mini MG servos but there's so much room in the radio bay that I'll just stick 148s or 3001s in it.  One good point is that the batteries can go anywhere they're need for balance, from the rear of F1back to F3 with no size constraints.

Wing bolt blocks installed in line with the wing bottom surface with a balsa infill bringing them level with the wing seat. I've tapped the ply blocks M6*1 rather than using captive nuts.

Edited By Bob Cotsford on 12/11/2017 12:59:34

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Hi Bob , the front deck may not be a perfect fit . As we all know there have only been about 16 of these kits ever made so the feedback loop is not really (and never will be) in place .

The foam decks also have a varying amount of "spring" in them making them curl or uncurl depending on moisture temperature etc .

However , looking at the photos , is it possible that it is the wrong way round ? The soft balsa square that it rests on should remain pretty much square , not sanded into wedge .

Something looks wrong ? Anyone else at this stage ?

Richard

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Hi Richard. The foam deck was definitely shaped correctly in plan form and sits perfectly against F2 with only minimal adjustment neccessary though it did need the suggested slots to allow it to be sprung in slightly to fit, but it was even along it's length at a couple of mm. The rear deck needed the same treatment. It would have needed a lot of bodging to fit the fron deck the other way round. With the wedge removed it all looks perfectly contoured and the canopy should fit failrly snugly, I'll confirm that once it's trimmed properly and the 1/8" sides are in place.I nitially there was a definite kink up behind the cowl, now there's a nice straight line.

Otherwise so far there's only the known issue of the fin foam core being 1/8" too wide at the front as Peter pointed out earlier, and the front tailplane segment being 1/2" too narrow (see a couple of posts back).

I suspect that the 1/32" bases for the wing fairing could be a shade (5/32"?) narrow if they're meant to go between wing and seat but I've not compared them to the plan yet. A few mm here or there isn't going to notice anyway.

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Yes , the photos are very helpful Bob . The shape looks right now and as you say , it could not be the wrong way round .

Would it be true to say, that if the base of the foam deck had a line drawn that started 1/4"in at the cockpit end tapering to zero at the cowl end , then that wedge removed with a sharp broad utility knife, we would have a deck that fitted ?

It would be good to come up with a simple fix for those that follow.

Richard

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That would work Richard, leaving the full 1/2" of balsa to blend everything in to the fuselage sides, not that it needed much blending.

The 1/32" ply wing fairing bases are the right size compared to the plan, just a slightly different radius at the rear. I intend to extend the ply along the full length of the fairing to make the sharp edge more resistant to hangar rash. I seem to have mislaid my bottle of Resin W, might be taken as a hint that my building board needs tidying. It's not even the small sized bottle.

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Oops chaps just noticed Bob’s photos and Rons post....I will update some of mine tonight. For tail wheel I am just using a standard sports tail wheel not a scale job. I didn’t have the same front deck problem as Bob as my foam deck was nice and square. The tail is slightly bulging despite my compression when fitted, but I can sort that and am happy with it . The front engine mount cutting and boxing is still underway. It was quite involved as mentioned earlier as I’m using the Laser 80 . I want to keep separate the airflow in front of F1 so oil or carb spray doesn’t enter the rest of the plane . I have been boxing in the cut out and added beams more beams will be added after I have fibreglassed the engine compartment. The distance from the face of F1 to backplate on the design is quite short. If I was starting again I would have put  F1 back by 2or 3cm to allow for length of 4s engines. At this stage in my build I’m just doing the White gluing. Wings coming soon ...Happy building. 🙂

Edited By Timothy Harris 1 on 20/11/2017 15:32:52

Edited By Timothy Harris 1 on 20/11/2017 15:34:01

Edited By Timothy Harris 1 on 20/11/2017 15:36:06

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Tim's right about the position of F1. I moved mine back by about 7mm but it is still a tight fit for a pumped 91 Surpass, not that there's that much difference in length from the non-pumped Surpass.

Tim, did you measure the height of the top deck from the crutch at each end? If yours is parallel I don't understand how mine ended up 1/4" high at the cockpit end.

I had some 1/4" balsa sheet too hand so I've used that as a doubler on the top of F2 to close of the deck and give the cowl extra support, and with the grain vertical to stiffen the bottom of F2 and again give more support to the cowl.

I've stitched a simple bent wire tailwheel leg to some of the 5mm offcut suitably sized to fit vertical in the rear fuselage with the leg emerging through the supplied mounting plate. If I decide I need it to be steerable on our grass field it will be easy enough to cut it off flush and fit a steerable one later.

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Will do tonight Ron. I only just did the cut outs this weekend as got motor last week . In terms of exhaust exit I well be allowing mine to protrude as it’s only about 1cm . I will make a removable panel to cover exhaust cut out in the fibreglass cowl , and also one for the cylinder head if needed.

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