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Chorus Gull

build/plan comments/advise

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will -015/08/2018 08:12:20
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587 forum posts
19 photos

Hi David

I have a chorus gull built as per the plans. Don't recall the wing rib thing, but it's possible I just made a set by sandwich method, or bodged it after.

Anyway mine is powered by an OS 60FP and it goes really really well, grooves round the sky. It's possible it is a tad nose heavy,, but it flies so well like this that I'm not worried. The only issue I have is that it's not the lightest of aircraft and is a bit slippery so can be a challenge to get it stopped on our patch in certain wind directions (or more of a problem with nil wind). If I were to build another I would probably consider adding flaps.

I would also makes sure the back end is as light as possible - mine has quite a bit of lead in the cowl.

Martin McIntosh15/08/2018 10:22:30
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3472 forum posts
1216 photos

Hi David, I missed that one which is of the 1/4 scale version.

I possibly confused the ribs with the Spiteful from the same publication.

David Hayward.03/12/2019 09:57:14
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176 forum posts
97 photos

I have at last started covering my Chorus Gull and I want to copy the red with gold trim as here. I will be using Solarspan for the red but have not yet sourced anything for the gold trim. Any suggestions as to what I could use? Will all the different types of covering stick to Solarspan? Any suggestions would be appreciated.

32182237747_a4834e0ae2_k[1].jpgmew_gull-1[1].jpg

Steve Jones 203/12/2019 12:39:59
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586 forum posts
431 photos

Hi there,

I have got one of these models , built from a plan and its fantastic.. fitted with an OS 91 FS.. which is a bit much but it cruises on half power and sound great.

Cockpit is scale and I took a trip to Old Warden where they had one and took load of pics.

Only comment I would have is for durability over the years as the U/C wires seem to have worn the holes in the wing blocks so they rock back and forward. On landing now its a nightmare unless you get a 3 pointer. Otherwise they swing back and dig in, pitching model up. O really need to cut the wing open and sort the worn mounting blocks but as the model is white solartex covered and painted i dont know the exact colour to match.

So, as yours is not covered i would seriously suggest you consider the wing mounting block system and maybe strengthen or sleeve before the covering goes on.

Steve

Bob Cotsford03/12/2019 13:11:45
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8642 forum posts
483 photos

For gold trim I'd be asking around local companies that do trade decals and trim for vans, vinyl wraps etc. as they may well have offcuts that you could use. Otherwise

Steven S03/12/2019 13:52:01
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367 forum posts
193 photos

Any local craft store that sells vinyl cutters should have some. The "Michaels" here sell 84 different colours, including a couple of golds.

David Hayward.03/12/2019 18:52:53
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176 forum posts
97 photos

Thank you all for your suggestions; much appreciated.

David Hayward.09/02/2020 12:01:42
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176 forum posts
97 photos

My Chorus Gull is finally finished so here are a few photo's taken along the way. I based this on the David Beale Mew Gull replica, and also scaled the plan up 20% to give the model a wingspan of 6ft. Scaling up meant I had to make my own canopy, so I will add another post with a video showing production of the canopy...chorus gull wing.jpgchorus gull wings.jpgp1040167.jpgfus-1.jpgp1040175.jpgfus-3.jpgfus-4.jpgcowl-1.jpgcowl-2.jpgengine.jpgmew gull-1.jpgmew gull-2.jpgcg-a.jpgcg-g.jpgcg-j.jpg

David Hayward.09/02/2020 12:08:41
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176 forum posts
97 photos

Here is the video showing production of the canopy...

Edited By David Hayward. on 09/02/2020 12:16:11

Martin McIntosh09/02/2020 19:24:30
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3472 forum posts
1216 photos

Why do you not get creases from the plug to the corners of the vac former? My last few attempts have been useless because of this problem.

David Hayward.09/02/2020 21:44:52
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176 forum posts
97 photos
Posted by Martin McIntosh on 09/02/2020 19:24:30:

Why do you not get creases from the plug to the corners of the vac former? My last few attempts have been useless because of this problem.

Well, probably more luck than design as I am no expert at vacuum forming, this being my first attempt. What you see in the video is actually my second attempt as I did not heat the PETG enough first time and ended up with a perfectly formed 3/4 depth canopy. I watched as many YouTube video's as I could find of people making all sorts of vacuum formed components and noticed the problem of creases forming at the corners. To try and counter this I made the plug about 1/2" deeper than it needed to be and then later also spaced the plug up from the vacuum form box by another 1/4" because I felt the 1/2" already added might not be enough. After the second successful attempt I did in fact have a couple of small creases but these were lost when the surplus depth was removed.

If I do this again I would just make the plug a good 3/4" deeper than needed. Other than that I guess it's down to heating the PETG to a high enough temperature and having good suction. Hope this helps.

Martin McIntosh10/02/2020 09:30:34
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3472 forum posts
1216 photos

I have probably watched the same videos as you and quite a few people had the same creasing problem. Have tried the usual oven heating, a heat gun and a combination of the two. I even modified my frame to have rounded corners, same result. Tried propping up the plug too; the vacuum and seal are strong.

I got through most of an 8x4ft sheet of PETG making the five needed for my Lancaster. I had more success the first time I tried vac forming, it must have been beginner`s luck also.

Thanks for the info.

Denis Watkins10/02/2020 10:35:55
4541 forum posts
123 photos

The sheet needs to be so hot that it will sag under its own weight

Then transferred to the vac forming machine quickly as David demonstrated

It's a good idea to have a look at bespoke machines

You see the heater above the sheet, and the sheet starts to sag

Then is pulled down onto the plug to be drawn down

Piers Bowlan10/02/2020 11:35:59
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2167 forum posts
53 photos

Beautiful work David, love the video too, you make it look so easy (it's not!). Looking forward to the flight reports.

Steve Jones 210/02/2020 12:18:39
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586 forum posts
431 photos

Looks great ,

What thickness of material do you use and what temp for the oven and how long would you say..

I know its trial and error for the part you are trying to form but some pointers would be useful please

Steve

David Hayward.10/02/2020 12:30:53
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176 forum posts
97 photos
Posted by Steve Jones 2 on 10/02/2020 12:18:39:

Looks great ,

What thickness of material do you use and what temp for the oven and how long would you say..

I know its trial and error for the part you are trying to form but some pointers would be useful please

Steve

Hi Steve, I used 1mm PETG bought from Trent Plastics, oven temperature was set to 230 degrees C and pre-heated for about 5 minutes. PETG was in the oven for about 3 minutes and I had to turn it half way as it was sagging quite a lot more on one side. I waited until the PETG was sagging by about 3" before attempting the 'pull'.

Nigel R10/02/2020 12:54:40
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3986 forum posts
721 photos

Very nice work David

Martin McIntosh10/02/2020 15:10:38
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3472 forum posts
1216 photos

Exactly as I have been doing David, only the gods were not smiling on me. What size is your frame, A3? I shall have a look at Trent Plastics.

Lucky with my 1/4 scale Gull. I picked up a perfectly sized canopy from a box of bits at a show.

I still have the female moulds for the grp u/c pants but mine are the long version which I prefer.

David Hayward.10/02/2020 18:21:00
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176 forum posts
97 photos
Posted by Martin McIntosh on 10/02/2020 15:10:38:

Exactly as I have been doing David, only the gods were not smiling on me. What size is your frame, A3? I shall have a look at Trent Plastics.

Lucky with my 1/4 scale Gull. I picked up a perfectly sized canopy from a box of bits at a show.

I still have the female moulds for the grp u/c pants but mine are the long version which I prefer.

Martin, the frame is 460mm X 260mm

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