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Chorus Gull

build/plan comments/advise

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David Hayward.01/05/2018 12:47:55
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156 forum posts
78 photos

Started new thread as advised...

Hi All, I have asked this question on other forums in order to capture as much feedback as possible, so apologies if you have already seen this post elsewhere.

I am preparing to build a chorus gull from RCME plan by Brian Peckham Feb 02. So far I have had the plan enlarged by 25% which gives me a 6ft wingspan. I have for example noted others have commented about issues with the wing rib sizes as shown on the plan, so this is one area where I would appreciate feedback.

So if you have built one of these from the RCM&E plan I woild be pleased to hear from you any any comments/advise you may have. Thank you

Here is a link to some information on this model...
**LINK**.

Geoff Sleath01/05/2018 13:30:08
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3145 forum posts
247 photos

I'll be interested to follow this as I've just completed a quarter scale Mew Gull from the Skyways Models plan-pack. I've had 6 flights so far and not one what I would call a good landing but I'm getting there. It's very good in the air and flies with authority on its 6S electric set up. How are you intending to power your Chorus Gull?

Expanding the Chorus Gull to 6' ws makes it the same size as my Mew Gull so it'll be interesting to see how it build and, perhaps more importantly, flies.

airfield 3 dec 2017.jpg

Prior to the test flight in late December last year. I removed the spats and they'll remain off until I master landing I've only flown it again in the past few weeks because of the weather.

Geoff

David Hayward.01/05/2018 14:01:23
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156 forum posts
78 photos

That looks nice Geoff. I am going to power mine with a 4 stroke ic, possibly a 90.

Trevor01/05/2018 14:13:11
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331 forum posts
47 photos

Hello David. I built an electric version of the Chorus Gull back in 2002. Details (including a number of subsequent mods) here: **LINK**

Trevor

David Hayward.01/05/2018 14:36:28
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156 forum posts
78 photos

Thanks Trevor, that's great.

Piers Bowlan01/05/2018 14:45:25
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1650 forum posts
41 photos

I have just read through Michael Parry's Chorus Gull build article from February 2002 RCM&E and I can't find any adverse comments regarding the rib sizes, presumably you have this article? I do remember reading about some issues with the plan but sadly I can't remember what they were. Hopefully someone else will have a better memory than I.

It's a lovely looking model and will look (and fly) even better scaled up 25%. Following with interest.

David Hayward.01/05/2018 15:34:25
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156 forum posts
78 photos

Thanks Piers, I do have the magazine article. I spotted a post on this forum which led me to believe there is an issue with the ribs as drawn on the plan, here it is: http://www.modelflying.co.uk/forums/postings.asp?th=11047

Edited By David Hayward. on 01/05/2018 15:35:24

Kevin Fairgrieve01/05/2018 18:32:47
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1558 forum posts
2834 photos

I built one a few years ago now. Mainly a hanger queen as I have far to many plane's and have my regulars. hmmm we have an "OLD" plane club event coming up soon.

Sad to say I cheated on the wings and had a set of foam ones made for me.

There are a good few picture's here.

And a build thread from another forum here.

Built using the full size plan and not the freebie from the mag.

I have a copy of the build article from February 2002 and the Original "Radio Modeller" article from March 1989. Can scan to PDF if required.

I contacted Trevor during the construction of mine asking for advice. A nicer more helpful person you could not wish for.

Kev

David Hayward.02/05/2018 21:09:29
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156 forum posts
78 photos

Hi Kevin, thank you for your response, liked your images and build blog. I have the RCM&E Feb 2002 article but not the original Radio Modeller article and so would be most grateful of a pdf.

Kevin Fairgrieve03/05/2018 18:22:01
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1558 forum posts
2834 photos

PM sent David.

yes

Kev

David Hayward.13/08/2018 20:15:34
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156 forum posts
78 photos

I am getting closer to doing some actual building; sum total of my efforts so far is the production of two wing rib templates.

I would appreciate some advice on building the wing which has a tapered chord and section. I have magazine articles from the original design in Radio Modeller March 1989 and also the later article in RCM&E February 2002, but neither goes into any detail about wing construction.

it's the tapered section element that I could do with some advice on. The ribs will be produced by the sandwich method. It appears to me the wing section should taper top and bottom from root to tip; this means I cant just build with the ribs from root to tip down on the building board as this would mean only the top of the wing would taper.

What this means is ribs from the root to the tip will have to be gradually spaced off the building board, also bearing in mind building in the necessary washout.

Firstly is my thinking correct? Secondly, if this is correct, is the easiest way of achieving this by including tabs on the ribs to provide the required spacing?

I have included an image of the two template ribs cut and in position for drilling.

chorus gull ribs.jpg

Kevin Fairgrieve13/08/2018 20:26:35
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1558 forum posts
2834 photos

I cheated!!

Got a set of foam wings cut.

Bilkits did them for me.

Kev

Kevin Fairgrieve13/08/2018 20:26:36
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1558 forum posts
2834 photos

I cheated!!

Got a set of foam wings cut.

Bilkits did them for me.

Kev

Martin McIntosh13/08/2018 21:44:53
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2676 forum posts
998 photos

Hey, I built the original some years ago powered by an OS 52S. Great model. I seem to remember that the published ribs were shown at the wrong size but a SAE got you the right ones. I sold this on to a club mate who is crazy on the Mew Gull because I built a 1/4 scale version powered (over powered) by a YS110 so if you bear with me I shall describe this in more detail.

I easily found a free PDF by Colin Usher on t`internet of the original, but re drawn by a lady, who unfortunately does not know the difference between a rudder and a tailplane as you will see if you look at it, but otherwise quite good except that one of the formers is way too narrow; quite a job to work out the correct size given the awkward shape of them. I could not wait for a mate to print it to 1/4 scale for me so `tiled` it; 64 sheets of A4! But not all in one go.

I much prefer the bubble canopy version and luckily found one from MRM at W&W.

I wanted this to be more aerobatic since the smaller one would do four point rolls better than many F3A`s so I mirrored the wing top section to the bottom of it which made it fully symmetrical and of course a little thicker.

The spats are a real problem so I made GF moulds for these, fixed with silicone, and halved the length of the torsion bars to stop the u/c bending back and the spats going through the bottom of the wing. The cowl is also GF. I should still have the moulds for these.

If the rudder was a bit bigger it would easily do the complete 1970`s style F3A schedule.

Piers Bowlan14/08/2018 05:43:27
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1650 forum posts
41 photos
Posted by David Hayward. on 13/08/2018 20:15:34:

 

it's the tapered section element that I could do with some advice on. The ribs will be produced by the sandwich method. It appears to me the wing section should taper top and bottom from root to tip; this means I cant just build with the ribs from root to tip down on the building board as this would mean only the top of the wing would taper.

 

What this means is ribs from the root to the tip will have to be gradually spaced off the building board, also bearing in mind building in the necessary washout.

 

Firstly is my thinking correct? Secondly, if this is correct, is the easiest way of achieving this by including tabs on the ribs to provide the required spacing?

 

No David, I don't think it is. I don't have the plan in front of me but just pin the lower spar to your building board and glue your ribs to that, not forgetting to pack up the trailing edge, - progressively increasing spacers to the tip to create the required washout. Don't build the wing 'off the building board'.

I am not a fan of foam wings but the Bill Kits foam wing cutting service looks very good value if you follow the link provided by Kevin. It might save you time and heartache if you are not comfortable building a tapered, washed-out wing. Good luck.

 

Edited By Piers Bowlan on 14/08/2018 05:45:40

David Hayward.14/08/2018 08:01:10
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156 forum posts
78 photos
Posted by Piers Bowlan on 14/08/2018 05:43:27:
Posted by David Hayward. on 13/08/2018 20:15:34:

No David, I don't think it is. I don't have the plan in front of me but just pin the lower spar to your building board and glue your ribs to that, not forgetting to pack up the trailing edge, - progressively increasing spacers to the tip to create the required washout.

Thanks for your response Piers.

So this would mean the wing section tapers only on the top of the wing from root to tip; the bottom of the wing will be flat. My understanding was that the root and tip ribs centres should be aligned as in the image I have posted - then you have even taper of the section top and bottom?

Martin McIntosh14/08/2018 11:53:44
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2676 forum posts
998 photos

You don`t need to worry about building in an underside taper since this will automatically appear when the wing halves are joined with a little dihedral. I do not remember bothering with wash out. The wing loading on mine is quite low and there is no tendency to tip stall.

The sandwich method is not a good idea for tapered ribs, much better to download the basic Profili s/w which will produce an accurate outline of each rib. You can easily add building tabs as well and use these to provide wash out. A foam wing would be rather heavy and look quite wrong since the design calls for a partially open structure.

David Hayward.14/08/2018 19:59:05
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156 forum posts
78 photos

Ok, thank you to everyone that contributed and thank you Martin, I can now see after doing a couple of basic drawings how dihedral effectively means the wing tapers top and bottom from root to tip.

Martin, I see you have an image of a Mew Gull in one of your albums, is this actually the Brian Peckham Chorus Gull I am about to build? Do you have any images of the build?

Martin McIntosh14/08/2018 21:17:29
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2676 forum posts
998 photos

Hi David, I think you mean the pic of the tail end which was just put there to illustrate the rudder angle or something. This would be the 1/4 scale version and I am afraid that I do not have any pics of the build.

The wing is very simple but due to not having any vertical sides the fus. really needs a jig of some sort but I do not remember using one on the 1/4 scale one.

David Hayward.14/08/2018 21:43:47
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156 forum posts
78 photos

Hi Martin, this is the image I was referring to from one of your albums....730035.jpg

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