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Vintage Model Company cub 4 channel trainer.


EGB 953
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1 hour ago, Keith Berriman said:

Hello EGB. Do not leave the wing partly covered as pictured as the film will start to warp the wing over next few days  replying from experience

That will only happen if you shrink the film before covering the top surface, you should cover both top and bottom before shrinking the covering film. Ideally you should shrink the top covering first with the wing pinned or held down onto a flat surface before shrinking the underside.

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7 hours ago, EGB 953 said:

I Followed the guidance of @Jonathan M and ordered some M2 Clevis and solder extensions which arrived. I need to think about the right technique for soldering - fill the cavity with solder and shove in the piano wire or is there a better way .... hmmm.

 

That sounds like it'll do the trick.  But take care to lightly abrade the piano wire first.  Also worth doing a test run on a piece of scrap wire first to test the process; you can always re-heat the joint to liquidise the solder and remove, but will need to clean the socket before final soldering.  Get yourself a solder-sucker, which is cheap but effective.

 

Agree totally about doing the covering in one sitting.  Tack film panels down around the outlines on low temp as you go, but only shrink at higher temp once the whole lot is on both sides.  If there are any warps (keep checking carefully by eye as you go) then give the opposite side a careful blast with a heat gun, then weigh down overnight. Try to only tack the film to the internal ribs and sheeted areas once you've got a smooth warp-free surface overall.

 

 

 

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The way I solder those threaded extensions is simply to clean and tin the piano wire and drop the extension onto the wire and apply heat.  You'll see if it's well soldered by the neat concave surplus solder at the joint.  I have a solder sucker but I only use it for electronic component desoldering - with other stuff I just heat it whilst holding with a pair of pliers and give it a good shake.  OK, it sprays solder over the floor but I've been doing it for more years than I wish I could remember without a problem - the molten solder is probably semi solid before it reaches the floor anyway.

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  • 1 month later...

So. After a rather a long gap caused by Xmas holiday and busy start to the year I have been progressing the past weekends. I covered and then did a trial fit of the ailerons and discovered the covering had warped one. Despite the heat gun I could t get it right so removed the covering in one side and started again. Much better result. 
 

I glued in the hinges and then re glued them to make doubtless sure they were properly in place before adding horn for both. I also added the horns for the rudder and elevator and the. Glued those carefully to the fuselage. I used a plastic set quite and masking tape to ensure the tail fin was at the right angle. The tail

palne was perfectly square - sign of how neatly the parts have been lasered. 
 

I waited for that for dry and then set to the pushrod links. My soldering iron episode not work, mind you been a while since I last used it, but a handy tip from someone at the flying club, used epoxy to glue the ends and then linked up. 
 

I then set up the throttle elevator and rudder to the prescribed throws. Fairly straightforward though the throttle did need quite a bit of EPA adjustment. 
 

so hopefully some time this week to set up the ailerons and add the wheels. Then balancing and adding stickers. I will need to tune the engine, want running smoothly when throttling up so I think I need to open the low rev valve a bit.  With some luck I may be able to do that next weekend if it is dry. 171D3C97-4B33-4A27-99BF-E74F5D1A1879.thumb.jpeg.565f3cf842a6aafcb578669daed9d2c1.jpeg675C1A12-F7B7-42E2-97C3-BC2FFEC5935E.thumb.jpeg.0f5c90e242cb6a8ba3d455b7b952f196.jpeg8A0173BE-5275-4BAD-9DAE-474CA5D21FE3.thumb.jpeg.70163ac49aca9e17a5f68a7cee3fe555.jpeg

 

Edited by EGB 953
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Well

spotted. That has been my intention! But discovered I had tailplane upside down. The kit and instructions are really good but it would be really helpful to have a proper plan as I would have avoided that error I think. Mind you my covering skills leave a lot to be desired. ?

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7 hours ago, EGB 953 said:

The kit and instructions are really good but it would be really helpful to have a proper plan as I would have avoided that error I think. Mind you my covering skills leave a lot to be desired.

Covering is just a case of practice, my first was no better, the key is knowing how far to go around the curve for the overlap.

The Mini Super has a full sized plan and designed for IC there is also plenty of help at the present time ?

It's part of the 2022 mass build so please join in.

 

Steve

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Great progress here in the build.

With any I/C motor, if servicable, and fully intact, it should only be a couple of minutes to tune both top and bottom needles.

The greater number of tuning and running problems occur with the tank height and plumbing.

You do have wiggle room here, before you build the tank floor in.

I fitted a SLEC tank.

 

IMG_20220206_220912.jpg

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So. Had some time this weekend to finish the model. 
 

I set up the aileron Servos to the described deflection and programmed them in, I have set up lower rates at 80% of that for the ailerons and  the elevator. 
 

then the wheels which were straightforward. I added a tiny drop of hot rocket to the lugs to stop them coming loose. Then added the stickers and the prop and spinner. 
 

dry weight comes in at 910g. So a bit heavier than I had hoped but hopefully still not too heavy. 
 

balancing on the main spar as advised by the instructions is perfect and with the fuel will be slightly nose heavy. 
 

so all that’s left to do is tune the engine and should be good for a first flight. I am sure it will be less stable than my Irvine Tutor trainer so must find a comparable aircraft on RealFlight so I can get some preparation in. 
 

oh I need to add my CAA operators number.  
 

 

56F14946-BD85-4DB0-AA1E-E684B791FE47.jpeg

4BE3F5FE-CCFF-4FD1-A343-B5A202C6F964.jpeg

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  • 1 month later...

So, over a month later, I finally got the chance to maiden the cub. Off to the flying field. Spent a good 20 minutes trying to get the engine running reliably. I noticed that it behaved much better with the battery still attached so wondered about the glow plug itself - not that much use but last run properly 27 years ago. I swapped glow plugs to one in my Irvine 46 and got a much better result. A bit of tweaking and we were ready to go. I got our club's top flyer to maiden her for me. he took her off, trimmed her out and handed her over, she flies well, nice and responsive but needs some rudder in the turn. Landed her ok, but those big wheels no match for thick and damp grass.

 

Second flight I attempted to take off form grass. Nosed over twice - not enough elevator. Third time held full elevator and she got going but VERY hard to control direction, took off didn't release elevator, so stalled and nosed into ground, luckily very little damage (one aileron came out, dowels snapped otherwise ok). So next steps: 

 

1. Replace dowel and glue aileron back in

2. Add more rudder deflection (it is less than spec and Club expert recommended it)

3. Mix some rudder in with aileron for turns

4. Buy new glow plug. 

 

On which point, any recommendations for which glow plug to buy? I have seen reference to hot and cold but have no idea. No idea on my Irvine one either, except it ran better> Any thoughts appreciated.

 

Lastly next flight I will try hand throwing it and only move to grass when it is warmer/dryer.

 

Image on the stand, prop looks odd because it was idling. Got some positive words from other flyers - not for my covering work mind you!

 

IMG_9230.jpg

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1. Use a Hot plug in a small motor.

2. Single wire undercarriage will bend back about 1" on take off and landing, putting your axle behind the leading edge, thus tipping the nose over.

3. Turn the rear of your silencer to point down, as this can fill with oil and stop the motor.

4. Yes Rudder is very useful.

Yellow is brilliant for showing up well in most weather conditions and shows off a lovely model.

Edited by Denis Watkins
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3 hours ago, Denis Watkins said:

1. Use a Hot plug in a small motor.

2. Single wire undercarriage will bend back about 1" on take off and landing, putting your axle behind the leading edge, thus tipping the nose over.

3. Turn the rear of your silencer to point down, as this can fill with oil and stop the motor.

4. Yes Rudder is very useful.

Yellow is brilliant for showing up well in most weather conditions and shows off a lovely model.

Thank you advice from everyone is very helpful. I have turned the silencer down, should I angle/bend the landing gear slightly forward to accommodate the impact of landing?

 

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UC looks to be at about the right position but as Denis notes if the wire is a bit on the thin side it may be flexing backwards with the resistance of the grass. A little bend forward could help but  best answer may be cut the grass.

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On 21/03/2022 at 21:52, J D 8 said:

UC looks to be at about the right position but as Denis notes if the wire is a bit on the thin side it may be flexing backwards with the resistance of the grass. A little bend forward could help but  best answer may be cut the grass.

I suspect you are right. Let’s see what happens next time! Thank you for the advice!

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So another good weekend flying, enjoyed four flights and 0 crashes. A few lessons learned:

1. Throw it from shoulder (as they do in the video on the manufacturer's website) don't try to take off from grass

2. Very hard not to nose over on landing (as they do in the video on the manufacturer's website), but on typical grass field while somewhat unsightly but means no damage done.

3. Flies very nicely otherwise, and quite fast (given I put a 15 TT engine on her).

4. Engine a bit temperamental, struggled to draw enough fuel, not sure if that is tank position or valve and air-bleed screw too far closed/lean.

5. 2 ounce tank a bit small so not long flight times (around 5 minutes) but plenty of power on half throttle and it wizzes around with authority.

6. The wing has an angle of incidence which makes it climb with power so I trimmed the elevator down a bit, I may carefully file down the fuse to make it a little flatter, but will leave for the moment.

 

So overall massively happy with it. If/when it has a big crash I will shift the engine back about an inch and move it down slightly so as to improve tank/carb level. Rebalance wont be an issue as I have the battery pack at the back end of the servo compartment. 

 

Anyone thinking of getting the cub, if you are new to the hobby or want a small chuck in the car plane, this is great, it looks really nice in the air and flies well. It would be better to have an actual plan fore the plane, for future purposes and would have helped with some slightly confusing points of the build.

 

My thoughts and recommendations for a purchaser:

 

If new to flying, go for the 3 channel version, wing is simpler to build and it will be easy to fly. if experienced, the 4 channel version is good and responsive, i would go for more power, it makes it a nippy little aircraft even in a bit of a breeze.

 

The build is generally easy but do check and recheck the video before gluing anything as occasionally it is confusing and easy to get the parts in the wrong place. I changed the kit from electric to glow, if you go the same route move the engine back about an inch and lower it. it changes the nose weight so you need to move your receiver battery as far back in the fuselage as you can

 

I went with the yellow colours scheme, which along with the provide stickers make it look really good.

 

And until you have really got used to it, don't try taking off form the ground, throttle up to 60% and a firm throw will give you success every time.

 

For the manufacturers (if they ever read this), please include the plan even if not 100% it will help a lot. Also some reinforcement of the wings where the elastics go and I would plank the first half of the front of each wing panel.

 

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36 minutes ago, EGB 953 said:

The build is generally easy but do check and recheck the video before gluing anything as occasionally it is confusing and easy to get the parts in the wrong place. I changed the kit from electric to glow, if you go the same route move the engine back about an inch and lower it. it changes the nose weight so you need to move your receiver battery as far back in the fuselage as you can

 

...For the manufacturers (if they ever read this), please include the plan even if not 100% it will help a lot. Also some reinforcement of the wings where the elastics go and I would plank the first half of the front of each wing panel.

 

 

To be fair to VMC I don't think many of their audience will be converting these to glow, and that is where I can see having a plan would really help. If you are building stock for electric power the absence of a plan is much less of an issue - that's certainly my feeling from the couple of evenings building I've done on the Spitfire. 

 

PS - Best way to get direct engagement with VMC is via their Facebook group (if you do FB)... I will post a link to this thread there.

Edited by MattyB
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