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Old Apr 13, 2010, 10:50 PM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
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Most,if not all, of the materials discussed as alternatives to balsa have been tried at one point in modeling history. And oddly enough balsa is the winner. There's a reason for that.

Knlever, if you're trying to find a substitute for balsa because you don't have ready access to balsa in Sri Lanka then we'd all be more than ready to help. But if you're doing this because you think it's better than balsa then you're fighting a battle that has already been fought and lost by many folks in many countries and at many times long past in history.

As for you're latest blend of cardboard and bamboo I think you're doing well with the materials. But no, I have not tried similar methods at any time. I did find that small split sections of bamboo were able to be heat formed as wing tips and tail outlines with great ease and have used this on a couple of old timer rubber models. As a result of these successes I'm always open to using bamboo in a more modern or original design but have not done so yet.

Your use of food skewers isn't using the bamboo to it's best potential by a long shot. Being in Sri Lanka you should be able to find bamboo in large sections with long runs of clear stock between the cell nodes. Go find some of that and learn to split it into long thin sections. Once you do that you'll have a good source of supply to material that is a worthy alternative to traditional balsa when it comes to building stick and tissue style models.

But for your gliders cardboard will always be an inferior material. It just does not have the strength to weight ratio to do well as a substitute for balsa or even a lighter softwood veneer.

Check around your area to see what woods are available as a veneer. Granted the cost will be more than the "free" of cardboard but in the end your models will be better.

Or if the goal of your modelling is to work with free and cheap materials then that is fine. But you need to stop trying to use these materials to directly replace balsa like you seem to be doing so far. You need to stop and design construction methods that optimize your local free or inexpensive material options. On that count your cardboard and skewer construction is not by any means an optimum design. The cardboard is not being used in a way that optimizes it's few strengths. And the bamboo skewers are overkill due to their size in this appication which means they are too heavy for the job they are doing.
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Last edited by BMatthews; Apr 13, 2010 at 10:55 PM.
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Old Apr 14, 2010, 01:53 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Balsa seems to be the best for this type of construction, so I am not saying there are better substitutes. Maybe carbon fibre or Cloroplast. But Balsa is not available here at all. There are several very experienced model builders in Sri Lanka who use Balsa for RC and free flight. The few modelers I spoke to have to import Balsa. If I am right it is rather cheap - a dollar or more a sheet - which is affordable.

http://www.specializedbalsa.com/prod...lsa_sheets.php

Also see Solabro

To come right down to it, if Balsa was available in Sri Lanka I would be using it at least in parts of the plane - the fuselage for example. Wings for example are a bit more difficult to make and give a smooth finish so it would be a cardboard laminate of some sort. If Balsa was available, ( it may be soon enough ) then I would be asked "so why don't you use Balsa?" and I would have no answer for that , as above

Recycled materials are great because they are free. The cost of one cardboard box is zero. The cost of 100 boxes is still zero. There will always be a place for paper and cardboard constructed toys and models.

Well yes I am trying to build a Guillow type model using the methods shown - is there a better arrangement of materials - say corrugated cardboard for something other than bulkheads? I am going for a Dassault Ouragan as first model

"Once you do that you'll have a good source of supply to material that is a worthy alternative to traditional balsa when it comes to building stick and tissue style models."

Ok so we agree on this. I have found some bamboo supplies. And tissue is available.

My final goal is to build a free flight EDF 'toy' and publish the plans, maybe offer a kit. Cost is the issue - with free materials, a small pager motor and a battery or capacitor it is within reach for those who want to try.

I saw an Air Hogs free flight plane in a toy store here the other day they were pricing it at around US $ 60.00. On the other hand the RC helicopters are available ( the small infrared ones ) for between the equivalent of $ 25 to $ 50 so that is reasonable.

I hope what I hope to achieve is clear - for me and education that will lead me to build RC planes in the future ( maybe cardboard?) and offer plans. For people who want to try, a cheap and attractive EDF model plane they can fly in the park as an alternative to rubber powered models and an intro to model planes leading on to RC.

And for the children of the world, making it easier to get their parents buy them a nice toy
without having to spend much money, and practice in model building.
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Old Apr 14, 2010, 11:28 AM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
11,417 Posts
For now just play with ideas. If you decide to go into kit making that should be something for the distant future. For now you've got a long way to go to learn how to build models with this stuff in ways that optimize the application of the materials.

For starters I'd say you should be looking at card stock that is thinner such as file folders and business cards. Corrugated cardboard is too thick and heavy for most uses in a small model unless it's being used for something where the double layer makeup provides stiffness.

I'm also wondering if file folder card stock could be hardened by coating it with varnish that soaks in and hardens to form a sort of paper composite which would be tougher and more damage resistant than the card stock on its own. That may be something to play with that might be interesting.

The thing is that at this point you want to play with the materials themselves to find out what works, which is lighter but still strong enough and more importantly which can be light and rugged enough to withstand the inevitable hard landings. From there test the results by making up simple models with the materials and techniques. Once you know the strong and weak points of your lighter weight options then you can think about designing fancier models to try out your ideas. Only much later should you even worry about kitting. You've got a lot of testing and learning to do first. And at the core this is YOUR hobby and you should be having fun with it and not worrying about how many kits you'll make at this stage.
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Old Jul 24, 2010, 11:28 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Back to restart this project

With the initial success of the wing design for the rubber powered project and the scale HLG, I will be going for the Dassault Ouragan 1:20 scale as a glider to start with:

Dimensions: Span : 13.16 m Lenght: 10.73 m. 1: 20 scale it will be

Span : 0.65 m , Lenght: 50 cm approx. Planning comes next:
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Old Dec 18, 2011, 08:12 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Flying the the Starfire glider got me thinking that it would sail along nicely with EDF power. In the interim it seemed a good test bed for the EDF micro free flight project:

This motor weights 30 g and is just too heavy.

http://www.hobbyking.com/hobbyking/s...z_Thrust_.html

Anyone have a micro EDF that will work with it?

Maybe I will just build one.



This should kickstart this project nicely.
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Old Dec 19, 2011, 07:27 AM
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perttime's Avatar
Tampere, Finland
Joined Nov 2004
4,270 Posts
People are talking pretty small EDF at:
http://www.rcgroups.com/micro-edf-je...r-systems-650/

I suspect the Starfire fuselage might not be quite ideal for an EDF installation (?)
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Old Dec 20, 2011, 11:36 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
652 Posts
Hardware

The motor will be mounted just behind the cockpit. The pictures show what I have: a motor and prop unit, a supercapacitor, and a small motor.

Can someone recommend a ducted fan for the motor shown?
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Old Dec 21, 2011, 06:58 AM
yes, its a flying lamb :)
draganbt's Avatar
Bitola, Republic of Macedonia
Joined Apr 2009
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Don't you think Superman will notice that his capacitor is missing?

I'm sorry I couldn't resist
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Old Dec 21, 2011, 09:49 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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So that's the secret of his power.

And I thought it was Kryptonite!
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Old Dec 22, 2011, 04:37 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Installation of Motor and Capacitor

Installation of Motor and Capacitor - three wires and a switch away from flight.

Will it fly - any bets?
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Old Jan 20, 2013, 07:28 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Thinking of reviving this project. I have learned a few things from my cardboard gliders, and feel I can build a lightweight, durable airframe now.

Need to know a few things, first of all, I need to fly it in a large stadium, 100m by 100 m , but test it in a small area about 15 metres x 15 metres.
  • How much of a motor run time will I need?
  • What sort of span loading should I aim at for a 50 cm, 60 cm and 70 cm model, say of a Mig 15?
  • Will a T/W ratio of 0.2 be enough for a slow level flight?
  • Nicad or Lipos or Super Capacitor? I think NiCads cut out suddenly and are easier to charge?
    Is the brushed EDF on Hobby King

    GWS EDF System 50 w/ motor (2.61oz Thrust)

    any good? I s there a chance it will burn out quickly?
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Last edited by knlever; Jan 20, 2013 at 07:36 AM.
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Old Jan 22, 2013, 01:47 PM
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stegla's Avatar
Guernsey
Joined Jan 2002
1,298 Posts
Hello knlever,

Check out this thread.
http://www.rcgroups.com/forums/showthread.php?t=1803743

*30 secs runtime is plenty.

*Try to get a T/W of .33 or better and use an electric f/f timer/regulator to trim.

*Lipo

Here's a link to my F/F Tunnan............... it would have to be bigger and the same weight to fly indoors.
http://www.rcgroups.com/forums/showthread.php?t=1266662

Good luck
Steve
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Old Jan 23, 2013, 02:57 AM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Thanks Steve.

I am now absolutely set on the Tunnan, seeing that Mikes Flying Model pages has the plans.
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Old Jan 23, 2013, 10:28 AM
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Guernsey
Joined Jan 2002
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Derek at Kpaero makes a production version of the 24mm fan.

In a moment of weakness a bit of dihedral was cracked into the Tunnan. Also I trim for a perfectly straight glide and powered-glide............. so when the power is cranked up, torque or a warp or something will hopefully make it turn.

Steve
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Old Jan 23, 2013, 07:04 PM
Just shut up and build!
Sri Lanka
Joined Mar 2010
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Steve

Had a look at the video of the Tunnan - a real joy to watch! Micro sized EDF jets have a sense of charm all of their own. The plane looks very good in flight, and we are used to see jet fighters more than props these days, so we can compare. Also, I have found from my building of scale chuck gliders that the jets are very stable, with their smaller, swept wings, longer tail moments and large tail surfaces.

Once again great flight, can't wait to build my own.
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