One bladed helicopters

[Barannfin]

Discussion in another thread concerning the BO-102/3 helicopters got me wondering. Why the h#1! would they make a 1-bladed helicopter??

Is the counterweight actually lighter than adding another blade?:confused:

Or was this maybe a purely conceptual test aircraft.

I don't imagine there are many experts on flying single blade helicopters. But we can certianly pretend to be ;)

[expedite_climb]

sycamore ??

Nature made it first. Clever bloke is the gaffer upstairs.

[ShyTorque]

Seems to me that the counter weight is just dead weight, better to use that weight to do some work, so shaping it like another blade is more efficient.

[Dave_Jackson]

Here are a couple of other ones; one old, one new.

Nagler-Rolz NR-55 (http://www.germanvtol.com/naglerfolder/nagler.html)
There is an old booklet (60-70 pages) floating around that gives the calculations, which Nagler used in developing this single-blade NR-55 helicopter.

Italian Light Helicopter (http://www.usbusiness.com/helicopter/ItProj01.htm)

[Barannfin]

Well it looks like it has been tried more than a few times. I think that I am a little confused here, physics wise.

I still can't get my head around why the single blade with counterweight would save weight. Doesn't the counterweight need to be the same mass as the opposite blade?

Wouldn't the extra lift from a 2nd blade allow you to make both of the blades smaller thereby saving weight???

I must be missing something major, otherwise why would they seriously try this?

[Grainger]

:eek: I wouldn't like to think what the single engine performance on only 68 hp would be like !!!

[Shawn Coyle]

There are some blade vortex interference issues to be considered. There was a one-bladed prop made for a Piper Cub that proved to be more efficient than the normal two bladed version.
My understanding is that while the single bladed rotor was more efficient, there were some pretty heavy vibration issues.

[Lu Zuckerman]

To: Barannfin

I must be missing something major, otherwise why would they seriously try this?

For the same reason a dog can lick himself. Because they can.

:ooh:

[ATPMBA]

I heard that the German one-bladed heli flew but it had some handling problem issues.

[Dave_Jackson]

The previously mentioned booklet is not on the Nagler. It is a 139-page report done for the United States Naval Academy in 1977. It is entitled 'Single Bladed Torqueless Helicopter Design'

The first idea was Forces on a Rigid Rotor (http://www.unicopter.com/temporary/SingleBlade.html) . The intent was to have the vertical component of centrifugal force balance the lift of the rotor blade. The coning angle was 9.34-degrees and the feathering axis looks to be at 5-10% of chord. Wind tunnel tests were done on a model. "When cyclic control was applied, the rotor blades would become violently unstable."

Two other ideas were tried and the third one apparently worked; at least it worked on a model.

It appears that no consideration was given to vibration.

[NickLappos]

A friend of mine, Rene Vanderharten, former chief pilot of KLM Noordzee, flew the Bo-103 way back when (early 1960's) and he told me the one-bladed design shook "pretty well" As Rene is relatively under stated, I would guess this means that it was pretty rough!

Here are some great photos of it:

http://www.hubschraubermuseum.de/Hubschraubermuseum_Buckeburg/Archiv/Bolkow_Entwicklungen_KG/Bolkow_BO_103/bolkow_bo_103.html

[Lu Zuckerman]

Eurocopter sent me a picture of the Bo-103 and it is the same as the third picture in the top row however one of the two pictures was printed backwards. Is it mine or the one on the website.

Speaking of printing pictures backwards the entire front cover of the FAA helicopter handbook was printed backwards.

:rolleyes:

[RW-1]

I once placed a shaped counterweight upon my Concept 30 RC Heli, just to show it can be done ... didnt take pics however.

It flew well, though cyclic rate was reduced slightly. "felt slightly mushy" I increased the radios rates to comphensate, and had no issues with it, I believe a web site is still out there who sells these counterweights for the model heli crowd.

It was more fun to demo the airflow around the heli by hovering next to a steam vent in colder weather anyways :)

I would agree with Lu, no practical purpose, more of a because it can be done type of thing.

[Dave_Jackson]

Maybe there is a future for one bladed helicopters. :oh:


US patent 6,619,585 dated September 16, 2003 ~

'Helicopter with single-blade rotor'

[Robbo Jock]

Maybe it's a size thing. Put the blade to the rear along the tailboom, then the counterweight is above and behind the nose, so you've got a shorter than average helicopter.

But is being able to fit the thing in your mark 1 single car garage worth having your eyeballs shaken out when flying it ? Probably not.