Jump to content

Vintage Model Company cub 4 channel trainer.


EGB 953
 Share

Recommended Posts

10 hours ago, Simon Chaddock said:

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.

DennisKitty.thumb.JPG.f8113e28e78156d2fe461e96b8c66ae4.JPG

 

  

What a lovely story! 

Link to comment
Share on other sites

  • 2 weeks later...

It has been a while since I updated the build log. I had a small hiatus when I discovered SLECUk had sent me the wrong sized engine mount. They were however, extremely helpful as soon as I reported it and sent me a replacement, superb service. This coincided with me having too much work so progress has been delayed.

 

While waiting for the engine mount I did get on with the tail fine and elevator. Inserting the hinges was just as fiddly and irritating as it was when I was a teenager and my efforts were not terribly neat. Still a bit of sanding should leave them looking decent.

IMG_8777.jpg

IMG_8784.jpg

Link to comment
Share on other sites

Anyway, having got the right mount, I glued the additional ply firewall to the one in the kit and test assembled the ply box to accommodate it. I also set up the 2-ounce fuel tank and trial fitted it (just the right size, my 4 ounce tank wouldn't fit). Once I was happy I attached the correctly sized engine mount and found it slightly too wide so I had to shave the sides by 2mm on each side till it fitted. I fuel proofed the fire wall with epoxy and then attached the mount once that was dry. i then assembled the ply box and glued it in place before coating the front section in two coats of varnish to further improve the fuel proofing.

IMG_8785.jpg

IMG_8786.jpg

Link to comment
Share on other sites

I then set about assembling the fuselage following the instructions. This is a very well thought through kit and it is quite easy to assemble and glue.  I added additional support to the fuselage and to the holes for the dowel that will hold the wings. Having to the sides of the fuselage glued and checked it was properly aligned, I attached then engine to the mount (I drilled pilot holes first) and that was fine. 

However, it was at this point I realised that the engine is considerably forward (and of course much heavier) than the originally designed outrunner and this means the weight is very far forward.

Fortunately, the receiver pack will be helpful in offloading that imbalance, especially if placed behind/underneath the elevator and rudder servos. I fitted these as well as the servo for the throttle and then planked the remaining components of the fuselage which generally came together quickly though I did do some clamping while the glue set.

IMG_8790 (1).jpg

IMG_8788 (1).jpg

IMG_8800.jpg

Link to comment
Share on other sites

On the subject of gluing - the Hot Roket thin cyano has generally been brilliant and aside from gluing myself to the model a few times, getting a headache from the fumes and getting through an entire bottle (it runs very fast), I would use it again. I have used some standard balsa cement I got from SLECUK which has been much easier to apply but obviously slower drying, which requires clamping of some variety but is very strong when it applies.

 

I was worried about overall weight - weighed the fuselage including the battery and receiver and it comes to 496g, wings should be about 110 and wheels are 80 so hopefully I can keep it below 800g and thus "only" 150g heavier than the electric version. I still calculate the wing loading to be quite low - overall wing area is 311 square inches so it should still fly - I  hope!

 

So next steps sand and cover  - I have been watching some good videos on how to avoid wrinkles, what worries me most is warping the wing, but I guess I will only learn by doing. Photos when i have made some progress -nothing exciting cub yellow oracover but hopefully a positive adventure.

Link to comment
Share on other sites

On 21/11/2021 at 19:53, EGB 953 said:

It has been a while since I updated the build log. I had a small hiatus when I discovered SLECUk had sent me the wrong sized engine mount. They were however, extremely helpful as soon as I reported it and sent me a replacement, superb service. This coincided with me having too much work so progress has been delayed.

 

While waiting for the engine mount I did get on with the tail fine and elevator. Inserting the hinges was just as fiddly and irritating as it was when I was a teenager and my efforts were not terribly neat. Still a bit of sanding should leave them looking decent.

IMG_8777.jpg

IMG_8784.jpg

At the risk of upsetting you, I would be fitting two hinges per elevator. One near the joined and one towards the tip.

  • Like 1
Link to comment
Share on other sites

On 21/11/2021 at 20:11, EGB 953 said:

I was worried about overall weight - weighed the fuselage including the battery and receiver and it comes to 496g, wings should be about 110 and wheels are 80 so hopefully I can keep it below 800g and thus "only" 150g heavier than the electric version. I still calculate the wing loading to be quite low - overall wing area is 311 square inches so it should still fly - I  hope!

 

At 800g flying weight you'll have a wing-loading of 13oz/sqft which is in fact quite manageable for a 42" span model.  But keep it two mistakes high until you're comfortable with its stall characteristics at slower speeds.

 

 

Edited by Jonathan M
  • Like 1
Link to comment
Share on other sites

@Jonathan M thank you for the advice on both counts. Hinges are glued so I can just pull them out. Regarding the stall behaviour - thats a good point, i will fly very high, thank you!  Looking forward to my weekend - hinges, sanding, some varnishing (fuel proofing) and then covering - something I remember enjoying as a kid.

 

 

  • Like 1
Link to comment
Share on other sites

On 27/11/2021 at 06:00, Jonathan M said:

Good lateral thinking, but for a model of this sort - weight, size, fuel residue everywhere - I'd personally prefer an adequate number of hinges buried in balsa, rather than surface-applied film which could lift and deteriorate over time.

So, heeding the expert advice on this forum, I started off by adding additional mylar hinges to my elevators, a process I did not enjoy. I then made the decision to glue them in and cover in one piece. Before that i sanded the fuselage and ran another two coast of varnish over the front end to ensure it will be as fuel proof as possible. 

 

Then to covering, which was a bit tricky, especially as I have started with the tail plane and rudder which both feature lots of curves. I confess I don't have the patience for taking it very slowly, but despite that I enjoyed doing it and after several hours I had those both completed, not very neat I confess but it will do.  I could then do one side of the fuselage before running out of time. That went a bit better and faster and looks better - mind you it is much easier. 

 

So pause again, hopefully i will get some time this week in the evenings or if not the end of next weekend. Plan is to finish the fuselage and do the wings, then final assembly. 

IMG_8817.jpg

IMG_8816.jpg

  • Like 3
Link to comment
Share on other sites

Haven't had time to work on this but been thinking about a few steps down the line - setting up rudder and elevator linkages. I like z bends, simple, easy to do and strong, plus more attractive than bulky options.  Should I z bend the piano wire at the servo end or the rudder/elevator end. if so, have to attach before i glue the horns in place, and, if any issues, harder to remove. Hmmm, got to think about that.

Link to comment
Share on other sites

8 hours ago, Geoff S said:

Put the Z bend at the servo end so the adjustable end is accessible when the model is fully assembled.   You'll need to fit the servo horn to the push rod before fitting it to the servo but that's not hard.

Thank you, that sounds sensible. What  would you recommend for the control surface end?

Link to comment
Share on other sites

I usually use stainless steel clevises (2mm mostly but 3mm for bigger models).  Fit a 2mm locknut and a short piece of fuel tube to prevent the clevis from opening (though they're usually very strong and the chance of their opening in flight is quite remote)

 

The 2mm push rods supplied by SLEC are actually smaller than 2mm and the 2mm thread at one end is rolled (like a bike spoke) rather than cut.  If the push rod is too short I use 3mm carbon tube which has a 2mm hole and glue 2mm threaded rod into the adjustment end with epoxy and a short 2mm threaded pushrod at the Z bend. Make the bend on the unthreaded part.  If you're using snakes then do the same (without epoxy) at each end.  Personally, I prefer push rods rather than snakes but snakes work OK just not as well IMO.

  • Like 1
Link to comment
Share on other sites

On 01/12/2021 at 22:33, Jonathan M said:

If you're going to use the supplied wire linkages (with z-bends at the servo ends), then the simplest method would be to solder on an extender with a screw-on clevis for adjustment at the control-horns:

 

https://www.rcworld.co.uk/acatalog/M2-Clevis-and--Solder-Extenders-Pk2-5508041.html#SID=59

Thanks! Great advice. I have ordered those. Not much building time this weekend, hoping to get some time on Sunday to finish covering the fuselage. 

Link to comment
Share on other sites

  • 2 weeks later...

So after not much time last weekend, I was keen to get stuck in this weekend. Sadly, that was not to be, but I did  get a few hours in. I covered the other side of the fuselage and then the underside and finally the top. My covering skills are not great - I struggle to be patient with the curves but am getting slightly better at it. I must say this Oracover is brilliant, easy to work with and looks good, even the bad bits. I have learned some important lessons I really should know by now - use as sharp a knife as you can and measure twice before cutting!

 

Having finished the fuselage, I trimmed the covering off the tail parts, heading @Nick Crippsgood advice to be very careful not to damage the balsa. I trial fitted it and it all looks good. 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.

 

Anyway, then onto covering the wings. the video directs you to add the aileron servos before starting covering but that made no sense to me so i covered the bottom half of the wings in two pieces. I used a heat gun to tighten it and it looks ok, though there are some areas I will go over with an iron at the end and once I can test for an warping. I also saw some advice on a video about using a towel to support the wing as you cover it - great advice and my wife offered me an old towel that colour matched ... ?

 

I then cut out the film and added the servos and threaded the wires but ran out of time before I could do the upper wing. I am not looking forward to the wing tips, big curves and I want it to look vaguely neat ... I may watch some videos on covering technique for tips.

 

Thats it for the moment, will either have lots of time this week and next week as my holidays start, or none at all if we manage to get away.  

 

I had a moment where I started worrying I should juts have gone for the electric option, certainly the build would have been easier and I would have finished by now, but I am where I am and despite the bumps am enjoying it. So, onwards ...

IMG_8836.thumb.jpg.f77906cb726d9fb7926c6a890b1bc88b.jpg

  • Like 2
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...