"On This Day" In Engineering History

The YR-45 helicopter with only 200 horsepower lifting 2581 pounds was more efficient than some modern helicopters which are rated at lifting only 10 pounds per horsepower.

Mr. Sikorsky certainly ventured into unknown territory with his creations. We all stand on the shoulders of giants to paraphrase Sir Issac Newton. I wonder who was Igor Sikorski's inspiration. Who's shoulders did he stand on? How did he move from the world of fixed wing to rotary wing aircraft? Wikipedia tells us little and no mention of possible affiliations with rotary wing pioneers such as Kellett, Cierva, or Pitcairn.

"The YR-45 helicopter with only 200 horsepower lifting 2581 pounds was more efficient than some modern helicopters which are rated at lifting only 10 pounds per horsepower."

What was the actual payload lift capability?

Helicopters have and alway will be an unstable platform. What the engineers do is take that instability and make it into an asset. Most high performance war machines mobility are based on unstable flight characteristics.

Mr. Sikorsky definitely is among those risk taking pioneers which we owe gratitude for his achievements.

I don't know what the YR-45 could lift as a payload. I do know that to lift it's gross weight of 2581 pounds out of ground effect with only 200 horsepower is remarkable even by today's standards.

Even supposing the YR-45 had power transmission efficiencies of 90%, 200 horsepower would net only 180 h.p. at the main rotor, actually less if you consider the anti torque tail rotor's requirements. Dividing that into the gross weight yields an astonishing 14.33 lbs lifted with each net horsepower.

Not too many of today's designs can better these figures. In fact a quick look in Google under "helicopter weight to horsepower" offers the standard figure of 10 lbs. gross per one hp net.

I expect that the weight to horsepower figure of 10 lbs is skewed by inclusion of military and non military helicopters. I'd be interested on the figures as applied to something like the Hughes 500, which has good crashablity from pilot reports. (Bell Jet Rangers were reported to stick in the ground, whereas Hughes 500s rolled and broke the tails off. The disappation of impact forces apparently favored pilot survival in the Hughes.) Pounds of thrust equivalents to horsepower may well be called for as far as the full story is concerned since many modern helicopters are turbine powered machines.

I've long wondered why the Osprey used rotors instead of ball gimbaled turbo fans considering the stresses involved turning to horizontal. Far as I understand aircraft design it is the engine you design the craft from, instead of the other way around.

Of course Mr. Skorsky did wonderful work, and it is nice to be reminded of it.

"I've long wondered why the Osprey used rotors instead of ball gimbaled turbo fans considering the stresses involved turning to horizontal. "

Could be complexity between the two.

"I expect that the weight to horsepower figure of 10 lbs is skewed by inclusion of military and non military helicopters."

Sorry to take so long to get back to your post but let me correct your assumption that a mathematic derivitive such as a ratio is influenced by the use or origin. For example; a 3:1 gear ratio is the same whether it is in a race car or a tractor.

To quote Wikipedia " A ratio is a quantity that denotes the proportional amount or magnitude of one quantity relative to another." Therefore a weight to power ratio cannot be "skewed by inclusion of military and non military helicopters". Quantities as used in ratios are independent of origin or use.

A weight to horsepower of ten gross pounds lifted by one horsepower is considered to be near ideal for helicopters of any type, of any use, or of any origin. Mr. Sikorsky exceeded this figure of merit by nearly 50%. That is an exceptional achievement and so far few (if any) helicopter designs since have exceeded a gross weight to power ratio of nearly 15 to 1. This is quite a testament to his genius.

I knew I had something wrong, and suspected that there was something wrong where you have pointed out. I never doubted Mr. Sikorsky's genius.

What my curiosity now is which helicopters achieve most closely that ideal now?

Since Mr. Sikorsky is an acknowledged genius, and his designs have been known of and around what has prevented others from duplicating his feat?

Sometimes machines that are at the edge of design possilities are as hard to handle as a wild horse. The Bee Gee and early attempts at the flying wing sans computers and jet engines come to mind.

So Teajonkwando I hope you will let us know what modern helicopters you find that impress you.

I myself have come to feel that ducted fans are more the way to go. I saw somewhere that a ducted fan flying car was actually certified and for sale, but haven't seen one.

Last I knew the SkyCar was doing tether testing over a pond but thought that the powersource, while admirable as a goal, wouldn't supply BTU engine bang. Since I don't see any ducted fan machines doing helicopter chores, then I may be completely mistaken, though I am imagining a turbopropfanjet engine where say on the Osprey the tilt rotors go. For my imagined large circumference fans to not be overcome by pressure drag I'd have to somehow put short wings on the turbine cowlings themselves and call on all flyingbody knowledge possible.

The Landing gear would be ideally long and retractable. Stacks of wings on the ducted turbofans themselves so as to elimanate rotors is the sort of machine I am thinking of. I saw a design that used a radical multi layered wing design that would be useful. It was reported to be slow but might be the compact lift thing I need to keep wingspan or rotorspan down and superior to landing footprint over the rotor design.

Not that I've got a job thinking about these things and told someone as I was digging a ditch, it's nice I'm not going to get fired for being wrong about something here.

That hummingbird and that seagull, I tell you they can fly. Those bees sure are impressive!

I'd be interested in helicopter pilot reports about what Mr. Skorsky's Helicopter of 1946 was like to fly.

I've unfortunately never flown a helicopter myself though I've been in them enough to know how easy it is to hit things in them. (The story is we matched speed on final parrallel to a Boeing 727 aiming for the ramp and recognized we hadn't hit the tree, after not.) I did get to fly a DC 6 once.

Finding answers to your questions is what research is all about. There are many sources. Wikipedia for one, or Google (with 17 million 400 thousand references to helicopters). There are more sources and all should contribute answers to your present questions and hopefully stimulate you to ask more questions until you become our expert on vertical takoff and landing machines, stability and reliability issues, promising new designs and technology.

Research is essential to knowledge. Anyone can ask questions but only the researcher can provide accurate answers. 'Hit the books' Transcendian. I look forward to your blog. TK