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Author Topic: Beginners attempt at Scale Rubber Power, Guillows 17" Chipmunk  (Read 5281 times)
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Dan Snow
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« on: August 07, 2018, 03:46:26 PM »

Hi Folks,
Newcomer to the site and an absolute beginner when it comes to rubber power.
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MKelly
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« Reply #1 on: August 07, 2018, 04:07:50 PM »

Welcome to the site - lots of good folks and good info here.  The Guillows 900 series models can be made to fly very well, just take your time and use a light touch during building and covering.  I haven't done the Chipmunk, but I have built the Typhoon and Skyraider from that series.  Both flew well, the Skyraider especially.

Peruse through the build threads for lots of good tips and techniques, and don't hesitate to post questions.  Good luck with your build!

Mike
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Dan Snow
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« Reply #2 on: August 07, 2018, 04:26:22 PM »

Arrgh, I wasn't able to edit the original post, and haven't figured out the secret to getting pictures small enough to post.

Used to fly R/C 20 some years ago, just recently got the bug to build and fly again, and rubber power looks to be fun, interesting, and fitting in my budget!
 
Trip to the hobby store showed a definite lack of interest in free flight in my area, and kit selection was very thin. ( I will be scratch building but that is to come) I ended up with the Gui;;ows 17" DH Chipmunk.

Using advice from Flydean1 I dumped the cheesy vacuum formed nose and made a solid balsa one. I will also be moving the motor anchor from the stab leading edge to the 2nd bulkhead aft of the wing trailing edge.

So far with all structures built, everything but the covering weighs 21 grams. Is that good or bad?  And according to the plans using the stab and thrust line as zero the wing is at positive 2 degrees. This old brain has sometimers and I don't remember if that is incidence or decalage?  Anyway, is that good or bad?

Any help is gratefully accepted and appreciated. As soon as I can get back to said hobby shop to score some balsa I plan to build a Cub or similar design to learn to fly these incredibly fragile little suckers. (Did I mention how many times I had to repair a piece I wasn't gentle enough with?)
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Mooney
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« Reply #3 on: August 07, 2018, 04:48:14 PM »

I didn't build the chipmunk, but I built the Stang, Typhoon and the Raider.  Mine all flew pretty well.  One suggestion I would add is to make the slot for the horizontal stab larger so you can adjust w shims for trimming. The Stang and Typhoon flew best for me but met their ends from multiple repairs and simply wearing down and gaining weight.

I like the 900 series, fun models.  Might have to grab a chipmunk.

You won't typically see FF stuff in most hobby shops.  Luckily there are great on-line vendors that can hook you up.

Welcome


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« Reply #4 on: August 07, 2018, 05:56:07 PM »

My local hobby hobby shop has now got the entire series of Typhoon, Mustang, Chipmunk, Skyraider etc. and all laser cut. Quite tempting, although I have the original plans for most of them but not the Chipmunk, and could easily fabricate a kit using a couple of sheets of decent balsa. I have a Mustang that just needs a new wing and some decorated tissue - perhaps printed or maybe using doped on patterns, as seen in a youtube video. There are videos of the Typhoon and Mustang certainly and they do seem to fly very well. I think if you follow the instructions you are bound to have success.
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« Reply #5 on: August 07, 2018, 06:15:53 PM »

I don’t think that those kits are laser cut, they are still die crushed aren’t they?

Andrew
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Dan Snow
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« Reply #6 on: August 07, 2018, 06:27:14 PM »

I know mine was die squashed. I was able to do the bulkhead stringer notches by setting my scroll saw on it's slowest setting, using a #2 blade and an 1/8" ply backing sheet. I copied the bulkheads from the plans and attached them to the bulkheads as a guide. That is a task I hated with the small models, I could never cut them with an xacto blade without splitting the wood between the notches.

It seemed like the laser cut kits were about twice the price of the die cut ones.
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Snaky Stringer
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« Reply #7 on: August 07, 2018, 06:33:03 PM »

The kits I saw today were described as laser cut. They were in different colour boxes, too. Price about £18, I think.
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« Reply #8 on: August 07, 2018, 06:37:50 PM »

https://www.amazon.co.uk/Guillows-504-Supermarine-Spitfire/dp/B0006GZ2HE/ref=
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Konrad
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« Reply #9 on: August 07, 2018, 07:17:04 PM »

Don’t see any 900 series laser cut kits on the Guillow web site.
https://www.guillow.com/dhchipmunk.aspx

This is my on line vendor for Guillow kits. I find it is easy for me to spend $100 plus when I go down memory lane. I still buy a kit or two from my local hobby shop. Just about any Hobby Town USA franchise store has these and some of the smaller Dumas kits. While I love guillow kits, they almost universally need to have the rubber and prop replaced. I find that the props in the series 700 can be made to work well enough (not suitable for the 900 series).
https://www.acsupplyco.com/aerospace/guillows/guillowsmain.htm
« Last Edit: August 07, 2018, 08:53:27 PM by Konrad » Logged

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Mooney
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« Reply #10 on: August 07, 2018, 07:36:35 PM »

Interstingly, these 900 series seem to have light wood and will fly if built w supplied Mtls.  But obviously they can be improved upon.  A friend advised me to modify my Typhoon and that thing was a good flier.  But then I saw Joshua's wife Hope built one w less mods and it flew great...so...

I'm a fan of the line.
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« Reply #11 on: August 07, 2018, 08:56:59 PM »

If your browser doesn't get the photos down to 400K? These instruction should help.
http://www.hippocketaeronautics.com/hpa_forum/index.php?board=85.0
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flydean1
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« Reply #12 on: August 07, 2018, 10:17:32 PM »

Continuing...

If possible, open the center hole in the formers to allow room for the rubber motor and a winding tube.  Also, if possible, make some form of pitch adjustment.  Easiest is to construct an oversized stab opening and then adjusting stab with shims.  Once trim is optimized, the shims can be glued in place.

It may be a bit late to do all this.  For instance, the 2 degrees of up trim in the wing may be enough.

My first attempt at Free Flight Rubber Scale (Always Capitalize) produced dogs until I did two things.  Move the rear motor mount forward, and provide some form of pitch adjustment in the stab.  The other breakthrough a couple years later was the tube in a tube rear anchor, which you can read about in several posts.
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« Reply #13 on: August 08, 2018, 02:59:25 AM »

The kits I saw today were described as laser cut. They were in different colour boxes, too. Price about £18, I think.

My son and now my daughter are building the Hurricane and the FW190 in that series.  The construction is heavy, with too much wood, and the wood is a bit variable, but crucially the bits fit together perfectly, and the robust nature of the parts makes them handleable for a novice.  They are building them for the experience of building, rather than the flying capabilities and enjoying the process.

But you are looking at the wrong series, the chippy and the other mentioned are not in that series if models.

The wood is (unusually) 1/20” for many of the parts BUT the notches that are die crunched in are far wider making the parts fit sloppy at best.  Most of the kits I have bought have been awful in terms of wood quality and the die crunching.

The other major weakness is the way the wings attach, they come off far to easily ripping out the side of the fuse with them.  I have built a few, but you have to spend a good deal of time correcting and fixing poor and broken parts, which makes what could be a nice simple and pleasurable build a bit irksome.

On the positive side they can be made to fly quite well, and if they got around to laser cutting them, they would be a great starter scale rubber model due to their simple construction...

Andrew
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Snaky Stringer
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« Reply #14 on: August 08, 2018, 04:25:14 AM »

The ones in the local shop are definitely the same series as the Chipmunk and are laser cut. I think they must be quite a new addition to the range. The boxes are all different colours to the die-cut series, but basically the same design. I didn't notice until after posting that the picture was of a Spitfire, which of course is a different series. The laser-cut logo is similar on the Chipmunk series. I can go and look again today and ask the proprietor, who is friendly and helpful and a former Royal Navy bod - well post-war, Beira patrol and stuff like that - if he has an up-to-date catalogue. He does sell some Vintage kits, too.
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DHnut
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« Reply #15 on: August 08, 2018, 06:44:08 AM »

Who is your local shop? I am due in the Uk about the 14 August and will be staying in Kintbury and all my searching has not revealed any shops in the Newbury area.
Ricky
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« Reply #16 on: August 08, 2018, 07:50:34 AM »

i stand corrected then!

The 500 Series kit boxes have certainly been updated, the FW109 kit box my daughter has is a new one like the spitfire one you showed, James's Hurricane is the old style box but with a laser cut logo sticker on it (to use up the old boxes I would guess) The pictures on the website it is still the old box, but it mentions that they are laser cut.

The 900 series one may well have been updated, but I can't believe Guillows haven't mentioned it, unless they have a lot of old die cut kit stock to shift!?

I guess the person to ask is Howard (Kittyfritters) he did some work with Guillows and (i think) he designed the new Porter and Beaver laser cut kits for them...

If they have then great, I will keep an eye out for them to build with my boy, and girl...

Andrew

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Re: Beginners attempt at Scale Rubber Power, Guillows 17" Chipmunk
Re: Beginners attempt at Scale Rubber Power, Guillows 17" Chipmunk
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DavidJP
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« Reply #17 on: August 08, 2018, 08:06:22 AM »

Hello Don.  You might be surprised at the number of folk who have joined this site after a break for example and forsaken radio for “little rubber models”.  And it is not necessarily due to finance!  So you are in good company.  

I cannot comment on any of the kits mentioned because I have never built any.  A “thing” from my formative years.  However some of the kits from the smaller concerns and cottage industries are excellent.  I can say that building from a plan selecting your own timber does pay dividends and makes cutting rather than crushing a piece of cake.  It is remarkable too that many models we built as youngsters which flew not at all now seem to be good flyers.  Well not remarkable really - we are now more careful over the build.

I do hope then you will stay with us and report on your exploits.  You may find the selection of the right kind of motor a bit of a challenge too later on.  And then there are the glues - slightly against the trend I favour cyno for small models.  Applied with the clipped eye of a needle.  Cuts building time noticeably.

Have fun.

Andrew - good to hear they are both at it - but are you not going to have to deal with further sibling rivalry?

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Snaky Stringer
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« Reply #18 on: August 08, 2018, 09:15:10 AM »

Apologies folks. I was deluded. The kits were all on one shelf and the laser cut logo led me to think they were all laser cut. Alas, the Chipmunk, Mustang, Typhoon and presumably the rest of the 900 series are all still die cut. They are being sold at the same price as the 500 series. Potentially, I suppose they are likely to be better fliers because of their simplified structure, but for building pleasure I think I'd prefer the heavier ones. There is plenty of scope for lightening the 500 series, but would it be worth it?
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Dan Snow
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« Reply #19 on: August 08, 2018, 03:10:42 PM »

Well, I'm Very Annoyed at Guillows right now.

The dihedral is set by the angle of the root wing rib, which is set by a die cut piece attached to the main spar.  According to the plans the dihedral is supposed to be 11/16" per panel. As built it is more than Twice that!!! AARRGGHH!! 

I guess my only course of action now is to cut out a pair of root ribs from the sheet stock scraps and try to sand then to the right angle to at least get the dihedral reasonably close to what the plans call for.

When I bought the kit there was something that nagged a little about the name Guillows, but with the limited selection I did have a lot of alternatives. Just have to keep working at it.
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Konrad
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« Reply #20 on: August 08, 2018, 03:26:25 PM »

What type of glue are you using? Carpenters wood glue (Yellow or White) you should be able to break the bond with hot water. If using acetate glues acetone works. I've even had some luck debonding CA with acetone.
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Dan Snow
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« Reply #21 on: August 08, 2018, 03:39:58 PM »

I use primarily CA, occasionally wood glue where I need time to fiddle things in place.

I had thought about trying to cut the rib loose but the wood supplied is so thin and soft, plus the leading edge, spar and trailing edge all protrude past the rib into the fuselage. I figured my chances of getting the rib loose and then glued back on while maintaining a flat surface to glue to the fuselage on a scale of 1-10 started somewhere south of -50 and went down from there.
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« Reply #22 on: August 08, 2018, 04:05:15 PM »

Sorry for addressing you as Don above.

Have you considered using a safety razor, which a thinner than scalpels and xacto blades and cutting the glue joint?  I find this can work and if you have used cyno the surrounding word will be a little harder and cut better.   The proprietary de binders also work I find. Acetone will work but better if it is pure and not he diluted stuff sold as nail varnish remover.

Good luck any way.
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Dan Snow
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« Reply #23 on: August 08, 2018, 04:38:25 PM »

Thanks but I'd feel more comfortable making a shim than using a safety razor blade, just funny that way.  Grin 

I'm very confused now.  The dimension on the plan for the dihedral is on a 60% scale front view. And on that view the dihedral actually measures close to 11/16"!  So now I'm wondering which is correct?

Has anyone built this kit?

And I  haven't really thought much about the covering yet.  I've seen many videos touting the advantages of Uhu Blue glue sticks. Do they really keep the covering on when you shrink it?
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« Reply #24 on: August 08, 2018, 05:26:25 PM »

The last one I built was about 50 years ago and I used the angle fixture, no measurements. As I recall at the time with my limited knowledge all I wanted was the tips to the bottom of the canopy (real sound aerodynamic reasoning  Roll Eyes ) and balanced side to side. I do recall the Chipmunk flew better than most of my other models at the time.
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