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Vintage Model Company cub 4 channel trainer.


EGB 953
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Having returned to the hobby after around ten years away and the last time I built a balsa model more than 35 years ago, I opted to start with something that looked fairly easy. The vintage model company 4 channel cub trainer looked the part with laser cut parts a simple design and video guides. Now I have an old Thunder Tiger 15 which I am going to use, so a bit of engineering needed as the cub is designed for an electric motor. 
 

I ordered the kit and it arrived in a couple of days, I must say the service  is impressive. I got a few extras to help with the build. The box is nearly

packed and The wood comes nicely sorted and sealed in plastic and the extras are all there. Especially positive are the great lol looking wheels. 
 

I wanted to start with the wing as that doesn’t require any modification and would get me started quite quickly but hit my first hurdle a, quite badly I think, warped main ply spar. See the photo. 
 

so my first question - how to eradicate the warp? I have it sitting overnight with a reasonably light weight pressing down to correct it but I am not sure that will be enough. 

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I agree with Keith on this one.

 

Wet the spar with a misting spray bottle on both sides and then weigh it down while it dries. If you are in a bit more of a hurry then steam the ply wood and again weigh it down until its dry.

 

I would not like to build a wing on a deformed spar.

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43 minutes ago, Andy Gates said:

I agree with Keith on this one.

 

Wet the spar with a misting spray bottle on both sides and then weigh it down while it dries. If you are in a bit more of a hurry then steam the ply wood and again weigh it down until its dry.

 

I would not like to build a wing on a deformed spar.

That’s my concern. Thanks for the tip!

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If you force the ply straight on the building board it will probably just warp the whole wing once it's built!   Not worth wasting time and balsa on a twisted spar - better to replace with a decent bit of wood.   If it's just plain maybe replace with a spruce strip.  

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5 minutes ago, EGB 953 said:

It is 3mm ply. Do you mean it shouldn’t be a problem?

What force is required to make it straight?

Very little I would assume.

Just looked at the build video.

 

We can stop talking about building boards and pins.

This is a self jigging slot together build.

I would slot the wings together and check for straightness this is all done before applying glue. Then take a photo as I am interested to see how it looks.

 

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3 hours ago, EarlyBird said:

What force is required to make it straight?

Very little I would assume.

Just looked at the build video.

 

We can stop talking about building boards and pins.

This is a self jigging slot together build.

I would slot the wings together and check for straightness this is all done before applying glue. Then take a photo as I am interested to see how it looks.

 

Thanks. Will have a go this afternoon. 

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10 hours ago, EarlyBird said:

Assuming the spar is 1/32 or 1/16 then the force required to pin it to the board will be minimal and have no effect on the straightness of the finished wing.

 

It is 3mm ply. Do you mean it shouldn’t be a problem?

 

8 hours ago, EarlyBird said:

What force is required to make it straight?

Very little I would assume.

Just looked at the build video.

 

We can stop talking about building boards and pins.

This is a self jigging slot together build.

I would slot the wings together and check for straightness this is all done before applying glue. Then take a photo as I am interested to see how it looks.

 

So following the instructions I got all the components for the wing out and separated. Came away easily and very neat too. These laser cut parts are excellent. 
 

Then onto putting it together. Despite the warped main spar it goes together easily and very quickly and in around twenty minutes it was ready for gluing with the warp almost imperceptible. Sometimes the video is hard to follow because the impressive young chap who does it moves to quickly and you have to try abs figure out which piece goes where. A few shots without his hand sun the way would help- as would a full size plan!
A little bit of testing suggested that the gluing would remove the rest of the issue so I went ahead. 
 

I confess I had forgotten how awkward super glue is with balsa especially the recommended thin cyano but I Confess it makes it easy to glue. So a few minutes later and it was done. I puts some grease paper underneath to I didn’t glue it to the Mat.  This was sensible as it did run through in a few places. 
 

I then left it to fully dry and made the ailerons which were a bit fiddly but went together easily enough. 
 

Tomorrow I will sand the aileron edges and tidy up any sharp edges on the whole wing. The holes are cut for the hinges but they will need covering first. 

 

then I will start on the fuselage. As I am going to put a nitro engine on I am going to double the firewall with another sheet of ply. Then add the engine mount after I have drilled the holes for mounting it. I will then have to see how the fuel tank fits. I have a four ounce and a two ounce. Not sure which to use - I do want to keep the weight down but two ounces may not provide very long flight times. So, TBC. 
 

enough for one day but I must say I had forgotten how enjoyable making your own plane is. 
 

 

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8 hours ago, EarlyBird said:

What force is required to make it straight?

Very little I would assume.

Just looked at the build video.

 

We can stop talking about building boards and pins.

This is a self jigging slot together build.

I would slot the wings together and check for straightness this is all done before applying glue. Then take a photo as I am interested to see how it looks.

 

Thanks for the advice. Much appreciated.  

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So I set out today to do the fuselage. Unfortunately, there was an error with my order and I was sent the wrong engine mount so I couldn’t drill the mounting holes. 
 

However I am following the rest of the instructions/video and I trial set up the engine mount ply box. It is as I thought, not strong enough for the engine so I used some left over ply to make a second firewall which I will glue to the supplied one. I will fuel proof it with some epoxy. 
 

I then set to making the landing gear, which involves  cutting then bending the wire to the correct shape. Cutting was a bit difficult but the evening was easy. I then stitched it to the ply former and tomorrow I will epoxy it while chasing up the engine mount. 
 

again, I would really like to have a plan to consult rather than the video. Much easier and as parts aren’t numbered either would save some time. 
 

I also found the 4 ounce tank is too big for the narrow fuselage so I will go with the 2 ounce one which will fit nicely and there’s room for some foam to keep it cushioned. 

 

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1 hour ago, Rich Griff said:

That's a nice big mat, can I ask where you got it please ?

 

I fancy the vmc spit, anyone done one yet, start a new thread for that as this thread is blow by blow account and interesting.

 

I fancy the cub also...

It’s the Ansio A1 self healing mat, bought on Amazon. 
 

The spitfire looks nice.

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I quite fancy their Hurricane.  Flag is about 25/30 miles from us and it's probably my nearest model shop these days.  20 years ago I cycled there to start a club ride but I think I'd struggle to get there now, even with a little electrical assistance, let alone back!  The difference between 60 and 80!

 

 

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On 09/11/2021 at 00:00, Simon Chaddock said:

EDG953

I note your plane was intended for electric but you intend IC.

You will have to make sure the engine mount & the fuselage area around it is strong enough. Remember electric is virtually vibration free. IC most definitely is not.

Just saying.

Yes and thank you for the advice. I got the wrong engine mount so haven't been working on it, but my plan is to add an additional  3mm  ply board to the firewall, and reinforce the formers with triangle stock as well as fuel proof the area with epoxy. The kit has the firewall attached to a ply frame which then links to the fuselage, so  I am hoping that should do it. what do you think?

 

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while waiting for the engine mount to arrive in the post, I headed off to the Shuttleworth collection at Old Warden. What a special place that is and surely one of the finest living museums in the world.  They have some extraordinary aircraft there and in more normal times would surely be a huge visitor attraction. It was very quiet when I visited, which was at least safe from a Covid perspective but concerning for the museum.

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EDF953

As long as you take into account the likely effect of the IC engine vibration and the effect of the fuel on the glue you should be ok.

 

I have a nice story about Shuttleworth. Many years ago I went with my late Dad to one of the open days. Their Avro 504 was parked in the sun with a low rope cordon around it.

My Dad as bold as brass stepped over the rope & walked up to the cockpit and peered in. Not surprisingly a rather agitated helper rushed over and they seemed to be  involved in a rather animated discussion. After about 5 minutes he walked back. Did you get into trouble? I asked. Not at all. The chap was the pilot and when I told him I had actually had a joy ride in a 504 for an 18th birthday present at Hendon in July 1926 with his older sister (so a 3 seat 504!) he was quite interested.

Part of the joy ride included a picture of the occasion.

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