Euro-Metric-GyroBee :-)

[Dzik]

HI All,
I m new here, I live in Poland and just started my first steps as gyrobee-builder.
To reduce cost I seriously consider building the gyro from as many materials available directly where I live as possible. Following this idea, I recognized that except from Dragon Wings and rotor head which I plan to buy in United States, everything I need I can buy in my country... but there is a little problem with metric dimensions (of course not re-calculating :-) but finding the best matches for original parts. There is no problem with angle stock and round tube which differs from original only in single milimeters but square and rectangular tubes which are available as standard in following dimensions:

-supplier: Bröderna Edstrand Group ( http://www.begroup.se/Application/User/default.asp)
-alloy: EN AW 6082-T6 (more durable than 6061-T6)
-50x50x3mm - price 5,90 Euro per 1 meter (sold in 6 m tubes)
-50x30x2mm - price 3,32 Euro per 1 meter (sold in 6 m tubes)
-80x80x3mm - price 9,22 Euro per 1 meter (sold in 6 m tubes)
-80x40x3mm - price 7,01 Euro per 1 meter (sold in 6 m tubes)
prices are from Poland

I figured out some possible configurations of mentioned tubes but none is very close to original - escpecially 80x80x3 for keel and double 80x40x3 for mast - but at least this looks safest and allows the same mast solution as in documentation.

other dimensions are far from original

My question is if any of european gyrobee-builders was also considering mentioned problems and what the effect was ? Maybe you know other aluminium suppliers that offer different dimensions (standard production)
I think that its worth trying because full (except from sheets) air-frame material costs app. 110 Euro (considering 50x50x3 for keel and mast) and you have lots of spare material... almost for another gyro :)

[allankaldmaa]

Hi Dzik

I think that you can use for keel 50x50x3mm and for mast 25x25x3mm tube. I also think that when you order from US tube 2x2x1/8 inch is it exactli the same as 50x50x3mm. You do not need to use 80x80x3mm tube.

Allan

[Dzik]

thanks for suggestion
I only wonder how splitting the mast into 4 instead of 2 rods influences its durability - will stress be distributed similarly for each rod? Maybe I should then add some mounting holes so everything is mounted to both front and rear pair of rods...?
I m not a metal engineer or experienced designer and can only predict from my imagination :) so if you have any further suggestions, I will be extremly grateful for any help :)

[Brent_Brown]

I have naver seen a 4 1 inchs tubes used before use 2 50 x 30mm for all of it.

[Dzik]

Yes... I thought about it and will never hesitate to use double 50x30 for keel and mast if it has walls 3mm thick.. but they are 2mm thick so I worry about it - Did anyone make some calculations regarding wall thickness? Is this 1/8" (3,18mm) a minimum or it is just "safe" dimension (we call it "armoured") in all conditions.
Most seriously, Im considering the following:
1-single 50x50x3 for keel and mast
2-single 50x50x3 for keel and 50x50x3 + 50x30x2 for mast (but then its differently mounted than in documentation, so Im not sure if much better than version no 1)
3-double 50x30x2 for keel and double 50x30x2 for mast (what about the thickness?????)

[allankaldmaa]

Useing alloy 6082 T6 you can use for mast single tube 50x50x3mm. Mast tube must be resistance for bending and for tension. Tube 50x50x3 has enough tensile and bending strenght for a small gyro. When you use 2 mast tube you probably want to enlarge bending strenght but so you only waste aluminium. If enlargeing bending strenght is real necessary you bette use single tube 80x80x3. It is only my personale opinion. I have plan to calculate some gyrobee details very soon and then I can talk about those problems more spetcificaly.

Allan
Estonia

[Dzik]

Thank you, Allan, for your oppinion.
I think, I will also try to make some more detailed recognition. Lets see what ultralight planes building companies (unfortunately we dont have gyro building companies here) have to say. Maybe I order some calculations from an aero-engineer or something.
PS: single 50x50x3 is also my favorite :)

[allankaldmaa]

I made last night some mast calculations and the results are: when you fly with you gyro with full power and your weight is 360 kg the mast will break if it is single tube mast 50x50x3. The twin tube mast will hold about 20% more. In my calculation I did not figure engine weight, rotor head mounting angle and some other details that will decrease bending moment in mast tube. So actuali 50x50x3 mast tube will bbreak when you put in the seat about 400-430kg.

Allan

[Dzik]

Today, I visited moto-glider manufacturing company to ask about some general calculations but received only zillion of reasons why not to build a gyro from people who know about gyros only a liitle :mad: ...but maybe there was one good suggestion - to use stainless steel also for keel and mast except for aluminium and now I would like to know your oppinion and maybe some suggestions about tubes thickness I should then use (I consider similiar tubes dimensions - 50x50 and/or double 50x30 with thickness range 1,5mm - 2mm)

Dzik

[allankaldmaa]

Stainless steel is not a good idea. It is about 2x stronger as al 6082 but 3x heavyer. I think you should not worry about that choice and you can use 50x50x3 al-6082 tube for mast. I do not know how many G force must Gyrobee endure but I think 4G is good enough.

Allan

[Udi]

It looks like you two are enjoying the challenge of reinventing the wheel. If I were you, I would buy a box of aluminum tubes in the US and have it shipped. The small shipping cost is well worth the headache you are going to save for yourself.

Udi-

[Dzik]

Allan: But I think, it is not so heavy (considering smaller thickness) that it shouldnt be considered at all - especially because of longer lifetime and full-dimension-range availability (the info. I given before is not true - I can purchase any profile dimension I want)

Udi: Following your idea I could buy ready to fly machine and stop bothering at all, and I would do it if I had money for it (I would buy Magni, btw :D ) So, saving app. 500 USD if I buy frame materials here is a real deal for me (its good propeller`s value, for instance). I m planning to build a gyro not in a week, a month or two but maybe in a year or even more, so spending a month for reinventing the frame doesn`t scare me so much :)
Maybe, if I start having headaches I will follow your suggestion :)

[greeny]

Hi Dzik

You might wish to check if "Alu Menziken" has a sales representative in Poland. This company used to produce nearly all the tubes for hanggliders and ultralights worldwide, that means for those aircrafts where strength vs. weight counts most.
If there is a sales point in Poland, they might advise you on which of their tubes fit your needs best.
Transport from Germany or Switzerland is a lot faster and cheaper as from overseas.

Peter

[Dzik]

Hi Greeny,
Thanks a lot for your info, it seems to be THE COMPANY I was looking for :)