Secret Helicopter
Thread Starter
Joined: Feb 2003
Posts: 373
Likes: 0
From: ON A HILL
secret helicopter
Designed and built in ten months made everything except the engine (500cc air cooled Rotax) Sitca spruce blades with glass fibre skin, alloy and fibre glass body. The picture shows its first tethered hover. Gotta show Frank we can do it in the UK in less than 22 attempts.
Joined: Jul 2003
Posts: 440
Likes: 0
From: Port Townsend,WA. USA
Bugdevheli,
Looks great!
There maybe hope for the sport heli after all.
Love to hear more details when you get back down to earth.
Rotor diameter?
Empty weight?
Rotor Head Type?
Do you plan to sell plans when the testing is complete?
Looks great!
There maybe hope for the sport heli after all.
Love to hear more details when you get back down to earth.
Rotor diameter?
Empty weight?
Rotor Head Type?
Do you plan to sell plans when the testing is complete?
Thread Starter
Joined: Feb 2003
Posts: 373
Likes: 0
From: ON A HILL
secret helicopter
Slowrotor. 20ft rotor span,8inch cord 0012. tail rotor 4 inch cord 0012. underslung teetering rotor head machined from solid alloy.main and tail rotor driven via v belts through a 90 digree gearbox to get drive from a horizontally mounted rotax. empty weight 385lbs. my calcs said it should lift with 500 rpm on main rotor, but it would lift of at 360. the plan with this machine was to see if i could get the sums right. The machine was very stable and vibration free. It was not my intention to do anything more than a tetherd test with this machine, it was purely to see whether i had the correct set up. I am now working on mk3 using a three cylinder bmw engine and a lot of composites to get that power to weight ratio improved.
Senis Semper Fidelis
Joined: Feb 2001
Posts: 1,288
Likes: 0
From: Lancashire U K
I'd love to see this thing, is that poss?
Hey TC, show this to your local big wig, he could get rid of all the cars and have all of N Wales covered so non of us could break the speed limit
Regs Peter R-B
Hey TC, show this to your local big wig, he could get rid of all the cars and have all of N Wales covered so non of us could break the speed limit
Regs Peter R-B
Joined: Mar 2003
Posts: 106
Likes: 0
From: Australia
bugdevheli, just curious as to the amount of sums you did before building, not being insulting it looks great.
Did you just work out what you needed and go from there? Or did you spend alot of time working out the parameters?
One more, what sort of vibration/structural analisys did you do?
Thanx
Did you just work out what you needed and go from there? Or did you spend alot of time working out the parameters?
One more, what sort of vibration/structural analisys did you do?
Thanx
Thread Starter
Joined: Feb 2003
Posts: 373
Likes: 0
From: ON A HILL
Secret helicopter
Spaced. got hold of a computor programme to give me power requirements, rotor diameters and blade sections etc. Drew up a frame using the theory that if it looks right it must be right, and just worked on it day and night. the stress analysys was only calculated on the rotor system as this was the obvious one that would bite me if i got it wrong. Paid meticulous attention to blade balance. The mistakes i made were on the vee belt drives as they would slip if you pulled collective too fast. Whilst i know to correct proceedure would have been design, stress calcs, build,etc beacuse it was only intended as a tethered test bed, i learned more from actually making it. It seems a common problem with anyone thinking of building one that the more they think about it,the more problems they see, and it never gets made. The big problem is once you have done one you cant stop, im on my third
Joined: Mar 2003
Posts: 106
Likes: 0
From: Australia
bugdevheli, thanx, and yeh the more you design the more you need to know.
Are the blades composite, if so what costruction did you use.
When are you going to have a page so we can keep posted on the progress of the MK3.
Are the blades composite, if so what costruction did you use.
When are you going to have a page so we can keep posted on the progress of the MK3.
Senis Semper Fidelis
Joined: Feb 2001
Posts: 1,288
Likes: 0
From: Lancashire U K
Hi Bugdevheli,
Could you not get away from the belt drive! I am aware that belts will save weight , but they are a scource of possible problems, just of late I have been storing some textile machinery from a Swiss manufacturer, as any machinery interests me I was interested to see some very small 90Deg power transfer boxes that were coping with something in the region of 100 SHP these transfer boxes were made from what seemed like Ali or magnesium with power shafts about the same dia as the tail rotor shaft on the R22, just thinking on a little, a transfer box fastened directly onto the side of the engine would present less mounting problems further down(or up) the transmission shaft to the main rotor .
Anyway keep telling us how far you have got with your Mk3
Regards
PeterR-B
Could you not get away from the belt drive! I am aware that belts will save weight , but they are a scource of possible problems, just of late I have been storing some textile machinery from a Swiss manufacturer, as any machinery interests me I was interested to see some very small 90Deg power transfer boxes that were coping with something in the region of 100 SHP these transfer boxes were made from what seemed like Ali or magnesium with power shafts about the same dia as the tail rotor shaft on the R22, just thinking on a little, a transfer box fastened directly onto the side of the engine would present less mounting problems further down(or up) the transmission shaft to the main rotor .
Anyway keep telling us how far you have got with your Mk3
Regards
PeterR-B
Thread Starter
Joined: Feb 2003
Posts: 373
Likes: 0
From: ON A HILL
SECRET HELICOPTER
Thanks for your interest vfrpilotpb and spaced. The blades on Bug 1 were hand carved/planed using templates, the wood was spruce. when the shape was correct, i applied a layer of glass fibre and then finished of with a gel coat to put the balance and centre of mass right. The finished blades gave me no problems at all. Regarding the belts. The drive to the rear rotor worked fine, but because of the reduction required from the engine to the 90 digree g/box in order to have a decent sized pulley on the crankshaft the pulley on the gearbox needed to be about 2 feet dia. Because it hovered, i just wanted to get on with mk2. you might be interseted in the latest machine i am working on! three and a half litre v8 tandem three seats 200hp called RAPTOR regards bug
Thread Starter
Joined: Feb 2003
Posts: 373
Likes: 0
From: ON A HILL
Secret helicopter
BMW K75 BMW rear angle box attatched to bell housing with a cush drive fitted inside. Then up a vertical shaft wich houses the sprag ,throught a ten to one chainwheel reduction to main mast. Rearwards drive throught v belts to tail.Now has head and blades on and has been run up. smooth as silk The tail end is carbon composite. Tempted to go all composite .
