Build Log 30 size coaxial building pictures

[copperclad]

hi
i've started building a larger coaxial and have been posting pictures in another thread , i figure it's about time i started a new thread to post these in ( apologies to spankedchrome for hijacking his thread ) , please feel free to jump in with any comments or ideas as i am open to any and all sugestions , thanks , dana

[spankedchrome]

Ha-Ha !.

[Krox]

Dana

Ok this is better..please move your latest photos over. I made some comments of the robust nature of the design.

Dan

[copperclad]

hi
parts for swash , still just need to machine the horns

[copperclad]

parts for gear hub with oneway

[copperclad]

upper rotor head

[copperclad]

hi Dan
yes , the whole central driveshaft looks massive , at 22mm it looks chunky to say the least , some of what you are seeing is that the parts are not finished , an example of this is the stabilizer bar pictured , the 3/8 square bar is just the stock i will cut out of , it will be chucked up in the 4 jaw and the ends will be turned down then center drilled and tapped , i need the square stock just where it passes through the head then the profile will transition to round , the body of the head is pretty much finished as pictured and i think proportionally will turn out lighter then the micro i just built up ( remember it's bored out to a 2.5mm wall thickness except for the very end where the grip bolts are ), i'm sure you know how this goes in that i have a clear picture in my head of what i'm building , and for me rendering it is as much art as engineering , when you see just a few pieces you are trying to guess the shape of say an elephant by just feeling it's trunk , i just have a few bearing flanges to turn and i will be on to the sheet metal work of the chassis which will go fast , i have a set of R-90 landing skids and should be able to post pictures of the initial frame up in about a week , the holidays are comming and will shoot a hole in my schedule but the closer i get the hotter i am to see it finished

as to having work openly discussed on the forums , i find being open and candid seems to reap the biggest rewards ,which for me is the exchange of information and ideas , whatever you make if someone wants it , there is nothing to stop them from just taking it and producing it , it happens all the time , look at the lama and the housefly , i could retire on a tenth the money thay blew in court fighting that whole mess , the hobbies are about having fun wheather it's flying or building or B.S.ing , and the forums are a great place to run into someone else who shares your interest no mater how obscure it may be , anybody care to guess how many people are scratch building coaxial machines at the moment , i bet its less then ten in the western hemisphere , 20 years ago we never could have had this conversation
and i have to add i have been having an absolute riot , building this and getting on here and talking about it , dana

[Krox]

Hi Dana,

The new thread is looking good.

Yeah I knew you were going to machine out the parts..the head looked beefy with the unfinished square stock going through it. Boring the head out to a 2.5mm wall thickness will make for some nice light parts.

On the topic of others stealing ideas and producing cheap clones.... It happens to all industries. With globalization of manufacturing and peoples' willingness to buy the clones there will always be a market for knock-off products. Like you I'm going to continue to post my ideas to share in the design and encourage others to try building their own helis.

You should add a link to the end of the last thread pointing people to your new thread. Then those following the design won't have to guess that this is your new thread.

Looking forward to seeing your progress.

Dan

[lesodell]

looks good ,every seen a airscooter?there is a pic of mine in my gallery

[copperclad]

hi lesodell
thanks , i have heard of the scooters but i think the one in your gallery is the first i've seen knowing what it is , it looks like you fly it , it looks really cool , and very similar to what i'm trying , but mine has no flybar but a stabilizer on the top set of rotors like a lama and it's a four servo design , 3 on the lower swash ECCPM and one more to control pitch of the upper rotor , so i will be a CP design and use independent pitch control of the two rotors to effect yaw , i made a smaller one that was just a copy of the lama , and this is my second model im working on to try pitch control , i'm basing it on raptor 30 parts , blades , blade grips , main gears , and then designing around them , it ends up only costing about 10 percent more then my smaller one based on shogun and trex parts , i should say everything exect the batteries , then your looking at a chunk of change , dana

[spankedchrome]

I thought you might like to have it , so here it is .

[lesodell]

yes i see yours is going to be quit different then a airscooter sounds like you will have a lot more control then the airscooter because it has very little

[spankedchrome]

How will you incorperate Auto-rotation bearings ? How do they manage on a heli like this ?, with a HeadingHold gyro ?.
It would be nice if you have the time to answer any quires , but I'd expect this thread is realy about the sole contruction of this heli .
Have you got a list up on the drive power unit/s yet?.

Intreasting , thanks.

[copperclad]

hi SC
good point and i'm very curious about it myself , a lot of what i have changed between this one and the smaller one i built , deal with problems and advantages found in larger helis , let me talk about an obvious problem first

with fixed pitch as the size increases there gets to be a serious lag between applying throttle and the blades actually speeding up , be it for yaw or climb , the bigger the disk the longer it takes to change the speed

this is why CP is such a nice feature , the head speed doen't have to change and a pitch change can happen very rapidly , again be it for climb or yaw the control input will effect the machine very quickly

once you have a CP machine , if the blades are big enough , you can autorotate if the rotors can freewheel , this is why i have added oneway bearings to the main gear hubs , the other reason is when you throttle down the motors act as brakes , this will cause the blades to swing forward against the hubs , once the blades have swung forward and are at what ? say 90 degrees to the hubs , the machine is in a great position to blade strike , by allowing them to freewheel centrifugal force keeps them slung out straight until their energy dissipates

think of the autorotation bearings in a raptor , the main gear has a oneway bearing in the hub , between the gear and the main shaft , in the pictures i posted above you will see i am doing the same thing on both main drive gears


i am guessing that with enough height cutting the motors and adding say 4 degrees of negative pitch , the main rotors should carry and even build thier momentum on the desent , i won't go into having forward speed or any thing else , lets just talk about the two rotors cutting down through the air , i would think the rudder ( changing the relation of pitch between the two rotors would still have the same effect as when it was under power ), i could be wrong , and it may have no directional control at all , but my guess is it would , all this is just speculation on my part and of course i could be all wet in my logic , but i'm getting to be in a good position to find out

i welcome anyones thoughts on this , as i'm mostly motivated by curiosity and this forum is a great place to discuss this topic

thanks , dana

[dacaur]

Wow this will be a truly awosme heli when you get it to fly!

As for rudder durring autorotation, I'm really not sure, on one hand, there will be no motor tourqe to diferentiate in order to yaw, but on the other hand, just the friction of the spinning shafts in their bearings might be enough to do the job as long as you have a heading hold gyro..... I guess only time will tell...