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Old Mar 22, 2010, 08:35 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Hank

I must say those small jet models are very beautifully done. The SAAB Tunnan especially

Just an inspiration for me.

http://www.ffscale.co.uk/page2f.htm
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Old Mar 22, 2010, 09:24 PM
B-17 freak
Vic Arcudi's Avatar
NE Italy near Aviano AB
Joined Jan 2004
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Knlever, I guess a 6x4 prop should do for running your cd rom motor on 2 lipos (7.4V). You'll also need a speed control for brushless motors. A great & friendly site for obtaining kits & hardware (I'm guessing you're in the UK) would definitely be: http://www.replikit.com/replikit2010...id=1&TreeId=29
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Old Mar 23, 2010, 03:05 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
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knlever,

The Guillows Me109 is built like a tank compared to how light you would need to build a small freeflight scale EDF model.. Guillows are very well known for being too heavy! Also at this scale forget normal film coverings, again too heavy.

By choosing small scale EDF jet you have picked one of the hardest of freeflight subjects. It will work but you need to be experienced in building very light, much lighter than your 109.. You also will have to spand some money on hardware, it's very hard to do a scale EDF model with cheap hardware. Your CD rom motor for instance wont work in a micro edf, it wont spin fast enough. For any brushless motor you will also need an ESC and some form of timer (timer replaces the radio receiver), to acheve good enough thrust/weight ratio you really are best go the brushless/lipo route and that does not work out cheap.

There is still one brushed fan i know of that will work with cheap Nicad cells.. this is the KP 44mm fan:http://www.kpaero.com/ProductReport....gory1=electric It is possible to build a flying scale jet with this fan but the need to build very light is even greater due to the poorer thrust/weight of the fan and batteries.... i actually have one of these fans and batteries for it stashed away somewhere....

I think though you may be better off trying a jet model powered with a prop. Prop power is much easier/cheaper to do. Your CD rom motor might work fine with a prop.
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Old Mar 23, 2010, 04:54 AM
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The windy west coast of Sweden
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I miss good old Jetex....





(I know there were drawbacks, but what I miss, is the simplicity, and also the thrill of playing with pyrotechnics ...and the fuel/fuse/discs were available most everywhere... )
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Last edited by Gluehand; Mar 23, 2010 at 05:06 AM.
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Old Mar 23, 2010, 07:44 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
12,130 Posts
Quote:
Originally Posted by Gluehand View Post
I miss good old Jetex....
Yes, the simplicity and fun factor of freeflight rocket power models is hard to beat. Itís what got me back into freeflight.

For my money though in terms of actual flying performance and simplicity of use Rapier motors are even better than Jetex. I can probably get two or three flights in with a Rapiers while the Jetex flyer is cleaning and re-loading his motor.. Also Rapiers are much lighter so the models tend to perform better.

Unfortunately Rapier availability is currently no better than Jetex. Production problems mean no Rapiers have been made for the last year. Rumour is that Dr Zigmund is in the process of making a new batch and that delivery is imminent.. but I've heard it before so Iíll believe it when I see the motors.

Steve
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Old Mar 23, 2010, 07:54 AM
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East Anglia, UK
Joined Sep 2002
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Quote:
Originally Posted by JetPlaneFlyer View Post
Vintage,
unless you are willing to do major transplant surgery on the motor mount the GWS EDF30 needs a 10mm motor, which until recently was a big problem because ther were no 10mm motors available that would give decent performance. The little Turnigy 1015 hopefully solves the problem though it does run very hot on two cells (it's designed for single cell Lipo batteries)

The GWS 40mm and 50mm fans will take 12mm motors and perform really well... it's probably these that you are thinking of

Steve
yes. 40mm.
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Old Mar 23, 2010, 10:04 AM
Master Chief
shin's Avatar
Joined Sep 2006
2,279 Posts
Quote:
Originally Posted by JetPlaneFlyer View Post
knlever,

The Guillows Me109 is built like a tank compared to how light you would need to build a small freeflight scale EDF model.. Guillows are very well known for being too heavy! Also at this scale forget normal film coverings, again too heavy.

By choosing small scale EDF jet you have picked one of the hardest of freeflight subjects. It will work but you need to be experienced in building very light, much lighter than your 109.. You also will have to spand some money on hardware, it's very hard to do a scale EDF model with cheap hardware. Your CD rom motor for instance wont work in a micro edf, it wont spin fast enough. For any brushless motor you will also need an ESC and some form of timer (timer replaces the radio receiver), to acheve good enough thrust/weight ratio you really are best go the brushless/lipo route and that does not work out cheap.



There is still one brushed fan i know of that will work with cheap Nicad cells.. this is the KP 44mm fan:http://www.kpaero.com/ProductReport....gory1=electric It is possible to build a flying scale jet with this fan but the need to build very light is even greater due to the poorer thrust/weight of the fan and batteries.... i actually have one of these fans and batteries for it stashed away somewhere....

I think though you may be better off trying a jet model powered with a prop. Prop power is much easier/cheaper to do. Your CD rom motor might work fine with a prop.
Hi
Another option would be to print out a paper model like the ones found here at the proper scale bond to foam and construct the airframe from that
https://www.fiddlersgreen.net/shop/c...name/Jets.html
Heres a build thread on a stuka constructed that way
http://www.rcgroups.com/forums/showthread.php?t=210521
Take care
Hank
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Old Mar 23, 2010, 08:44 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
That Stuka model is great. Models like these are a great inspiration for me - I cannot imagine the detail on that thing. And it flies!

How about durability?
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Last edited by knlever; Mar 23, 2010 at 08:51 PM. Reason: mix up
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Old Mar 24, 2010, 05:34 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Steve

I used to look for but never found a Jetex in the 1990s they were out of production

Have you seen this site : says "should fly with EDF"

http://jetex.org/archive/jetxfiles/200312.html

However, modern electric motors are eminently suited to the high power at extreme rpm that efficient ducted fans require. It will not have escaped the more perspicacious readers that there has been a revival of small free flight ducted fan models, made possible by the availability of powerful electric motors and light, energy-packed batteries. If one wants a relatively painless introduction to electric ducted fan (EDF), have a look the 20" span Hawker Hunter and associated KP power pack from Aerographics [right] (see Model Flyer, Feb. 2002). This model is comparable to the Jetex Hunter, and weighs 5-6 oz with batteries. It certainly flies well
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Old Mar 24, 2010, 05:39 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Steve

I think I will go ahead and build the airframe and then see what it weighs. Then I can see what sort of power I need. This will be a 15 second flight time or so model - built as a prototype of a toy or an introductory FF kit

The model will be a stepping stone to building an R/C EDF and RC flight. The enclosed EDF unit seems protected unlike a propeller stiking out there at the front where it is the first part of the model to impact.

If it weighs too much - back to the drawing board. Don't you just hate having to build models .....
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Old Mar 24, 2010, 06:07 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
This is what I have to aim for - it must have flown:

http://www.greatplanes.com/discontinued/gpma4000.html

SPECIFICATIONS
Stock Number: GPMA4000
Wingspan: 24.4 in (620 mm)
Fuselage Length: 21.7 in (550 mm)
Weight: 4.76 oz (135 g)
Requires: Six "D" batteries for the charger


100mAh NiCd battery are already preinstalled

I wonder what the motor was?
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Old Mar 24, 2010, 07:02 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
12,130 Posts
Quote:
Originally Posted by knlever View Post
- it must have flown:
i would not be so sure.....
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Old Apr 02, 2010, 11:37 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Construction method - corrugated cardboard formers

I have build a part of the fuselage as a test - using corrugated cardboard and bamboo skewers. Has anyone tried this before?

Seems rather light. Will build the complete fuselage and see
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Old Apr 11, 2010, 04:41 AM
Registered User
United States, CA, Riverside
Joined Feb 2003
201 Posts
Before you do that.....

Balsa is a material that is hard to beat for strength to weight ratio. Bamboo and cardboard are pretty heavy in comparison.

I suggest that before you build a whole airframe just compare weight of some components. Cut out a bulkhead or two, a few stringers in both materials and compare. I think you will find quite a difference.

Best wishes.

Dave
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Old Apr 11, 2010, 03:19 PM
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carbondale il
Joined Jan 2007
2,617 Posts
Awhile back I considered building a plane with foamcore board. It turned out to weigh about the same as balsa if not actually heavier.

Kev
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