The MiniMOB ~ RE-DESIGN STARTED.......... - Page 20

Hephaistos · Nov 03, 2009, 12:47 PM

Hello Mario.......

If You are talking about CATIA in the context of "back in the 90´s", I am pretty shure You are talking about the version 4 or lower. The current version 5 was introduced 1999, and it took some time to become a standard for the automotive and aerospace industries. The change from 4 to 5 is really significant, they only have the name in common.

I had a look for the rhino-software today. It seems to be more oriented towards some design-work than towards real construction in engineering. It offers very easy acess to create a 3D visualization, but I am in doubt if this is a 3D geometry in the way I would define a geometry. Easy manipulation of the geometry by just grabbing and pulling it with the mouse, but I really miss the geometric hardcore-stuff. If I create a point, I want to have the point visible in the history of the contruction, give him a name, rework his definition if its needed etc...........

Bye
Mike

Hephaistos · Nov 05, 2009, 01:26 PM

Hello..............

After we got a little side tracked, now back to the topic......

I got a little side-tracked myself, looking for SPAD-fixed-wings and things like this. I really like the simplicity of the coroplast-wings, but they are

heavy. If the wings are heavy, a very light airframe is needed. No possibility to use square aluminium tubes............

So I fixed the weight of the square-profiles to build the airframe and the wing-spars to 100 grams per meter, and started to find out how much strength I can get out of this given mass. It ended up with carbon-fiber composite with a core from balsa-wood. The epoxy is applied with vacuum-infusion. I made some tests to check if it could be working, it was okay, so next step is to order the materials needed.........

Currently, its 15x15 mm hard balsa for the core, covered with 0,5 mm unidirectional carbon-fiber-tube and the a carbon-fiber-sock with a 45° orientation to prevent buckling and to give some torsional stiffness. With using the vacuum-infusion, I hope to produce a spar that weighs something in between 100 and 110 grams per meter and can take a load of about 13 kilograms hanging one end when the other and is clamped.........

For a fixed-wing aircraft with a span of two meters and a weight of 2 kilograms like planned, the maximum possible load-multiplier is 26, or, in other words: unbreakable...........

While waking up and drinking the first coffee a few days ago, I sketched the airframe for the fixed wing, and, as I wasn´t awake complety, I put a rotor to the airframe. To my surprise, it fitted perfectly.........

So, thats what I have in mind: An unbreakable airframe made from this CF-balsa-tubes, which can be eqipped with some simple wings or a rotor. Trimming and weight seems to be okay, but it needs some work on the details..........

Bye
Mike

SafeLandings · Nov 05, 2009, 01:34 PM

Mike,
It sounds like it will be another masterpiece.

Could'nt you make the rotor blades in the same way???..unbreakable rotors

You will have to excuse me as I dont know what a Spad is? I was thinking World war I biplane

Regards Rich

Hephaistos · Nov 05, 2009, 02:33 PM

Hello Rich..........

Well, my girlfriend was making jokes on me like: "You prefer to make constructions instead of going out and learn to fly" She seems to be right about this.

I made some experiments with balsa and CF, trying to find some alternate for the square aluminium-tubes I used for the MiniMOB for weight reasons, and using the vacuum-infusion produced the best results so far, and its not as complicated as it seems. Sandwiching unbreakable rotorblades should be possible too if the things work like expected. And here is the extra-bonus: If You want, You can twist them while the epoxy cures to create some wash-in!

The main target is to build some fixed-wing trainer, using this tubes for the airframe and the wing-spars. If the rotor fits to the airframe to convert it to an autogyro, that would be cool, but its not a must-have.

BTW, SPAD is Simple Plastic Airplane Design, RC-aircraft build mostly from coroplast, coroflute or twinwall. Using this materials, building gets really simple. Just look at the SPAD-forum on RCgroups........

Bye
Mike

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Nov 03, 2009, 12:47 PM	#286
Hephaistos Tannenzäpfle-Terminator Join Date: Dec 2008 Location: Baden-Baden, Germany Posts: 397	Hello Mario....... If You are talking about CATIA in the context of "back in the 90´s", I am pretty shure You are talking about the version 4 or lower. The current version 5 was introduced 1999, and it took some time to become a standard for the automotive and aerospace industries. The change from 4 to 5 is really significant, they only have the name in common. I had a look for the rhino-software today. It seems to be more oriented towards some design-work than towards real construction in engineering. It offers very easy acess to create a 3D visualization, but I am in doubt if this is a 3D geometry in the way I would define a geometry. Easy manipulation of the geometry by just grabbing and pulling it with the mouse, but I really miss the geometric hardcore-stuff. If I create a point, I want to have the point visible in the history of the contruction, give him a name, rework his definition if its needed etc........... Bye Mike

Nov 05, 2009, 01:26 PM	#287
Hephaistos Tannenzäpfle-Terminator Join Date: Dec 2008 Location: Baden-Baden, Germany Posts: 397	Hello.............. After we got a little side tracked, now back to the topic...... I got a little side-tracked myself, looking for SPAD-fixed-wings and things like this. I really like the simplicity of the coroplast-wings, but they are heavy. If the wings are heavy, a very light airframe is needed. No possibility to use square aluminium tubes............ So I fixed the weight of the square-profiles to build the airframe and the wing-spars to 100 grams per meter, and started to find out how much strength I can get out of this given mass. It ended up with carbon-fiber composite with a core from balsa-wood. The epoxy is applied with vacuum-infusion. I made some tests to check if it could be working, it was okay, so next step is to order the materials needed......... Currently, its 15x15 mm hard balsa for the core, covered with 0,5 mm unidirectional carbon-fiber-tube and the a carbon-fiber-sock with a 45° orientation to prevent buckling and to give some torsional stiffness. With using the vacuum-infusion, I hope to produce a spar that weighs something in between 100 and 110 grams per meter and can take a load of about 13 kilograms hanging one end when the other and is clamped......... For a fixed-wing aircraft with a span of two meters and a weight of 2 kilograms like planned, the maximum possible load-multiplier is 26, or, in other words: unbreakable........... While waking up and drinking the first coffee a few days ago, I sketched the airframe for the fixed wing, and, as I wasn´t awake complety, I put a rotor to the airframe. To my surprise, it fitted perfectly......... So, thats what I have in mind: An unbreakable airframe made from this CF-balsa-tubes, which can be eqipped with some simple wings or a rotor. Trimming and weight seems to be okay, but it needs some work on the details.......... Bye Mike

Nov 05, 2009, 01:34 PM	#288
SafeLandings Registered User Join Date: Dec 2007 Location: Stourport on Severn ,Worcestershire, United Kingdom Posts: 2,139	Mike, It sounds like it will be another masterpiece. Could'nt you make the rotor blades in the same way???..unbreakable rotors You will have to excuse me as I dont know what a Spad is? I was thinking World war I biplane Regards Rich

Nov 05, 2009, 02:33 PM	#289
Hephaistos Tannenzäpfle-Terminator Join Date: Dec 2008 Location: Baden-Baden, Germany Posts: 397	Hello Rich.......... Well, my girlfriend was making jokes on me like: "You prefer to make constructions instead of going out and learn to fly" She seems to be right about this. I made some experiments with balsa and CF, trying to find some alternate for the square aluminium-tubes I used for the MiniMOB for weight reasons, and using the vacuum-infusion produced the best results so far, and its not as complicated as it seems. Sandwiching unbreakable rotorblades should be possible too if the things work like expected. And here is the extra-bonus: If You want, You can twist them while the epoxy cures to create some wash-in! The main target is to build some fixed-wing trainer, using this tubes for the airframe and the wing-spars. If the rotor fits to the airframe to convert it to an autogyro, that would be cool, but its not a must-have. BTW, SPAD is Simple Plastic Airplane Design, RC-aircraft build mostly from coroplast, coroflute or twinwall. Using this materials, building gets really simple. Just look at the SPAD-forum on RCgroups........ Bye Mike