Tip Jet Helicopters

Hi!
Dennis, "Shake & Bake!": can you elaborate? Can you give your opinion about tip-jets helico? Thanks.

Bryan, "Fuel consumption is a little high...": how much is little?

May be there is something there!?...


https://www.youtube.com/watch?v=hrgdcmYGDQ0

3 times the normal fuel burn of a normal power plant

noise just doesn't describe them

raw fuel spilled in a ring below the rotor tips

massive weight on the tips adds to vibration problems (node weights can't even help)

lose of a single engine = shakes everything like a wet dog

the most inefficient way to power rotors

If it was any good the main manufactures would of kept them around.
 
3 times the normal fuel burn of a normal power plant

noise just doesn't describe them

raw fuel spilled in a ring below the rotor tips

massive weight on the tips adds to vibration problems (node weights can't even help)

lose of a single engine = shakes everything like a wet dog

the most inefficient way to power rotors

If it was any good the main manufactures would of kept them around.

To quote Bubba; YEA. What he said.
 
I have always wanted to experiment with running a small compressor off a drive wheel like a pre rotator and feeding the air through a tube to a series of tiny holes drilled on the trailing edge of the rotors as a prerotation system.
Dont know much about physics so Im guessin it wont work, but seems like it cojld be made to work much lighter than a Wunderlich.
Also considered using compressed air in a fiberglass wrap tank at 4500 psi...
I imagine the vent air wohld be pretty cold due to adibiatic air pressure (impressive,hunh?)
Why would/wouldnt this work?
 
I have always wanted to experiment with running a small compressor off a drive wheel like a pre rotator and feeding the air through a tube to a series of tiny holes drilled on the trailing edge of the rotors as a prerotation system.
Dont know much about physics so Im guessin it wont work, but seems like it cojld be made to work much lighter than a Wunderlich.
Also considered using compressed air in a fiberglass wrap tank at 4500 psi...
I imagine the vent air wohld be pretty cold due to adibiatic air pressure (impressive,hunh?)
Why would/wouldnt this work?

Take an air-hose from your compressor and stick the little rubber end up to the little hole on the end of your McCutchen rotorblades and give it a shot. The result would be the blade instantly exploding apart.
.......How do you think I know that? :-(

To prevent this would require plumbing throughout the blade as well as to any outlets.

It can be done. It's just not worth the effort and results when mechanical methods are more practical, available and more efficient.
 
Last edited:
Would aluminum Sport Rotors type make a difference?
And on that thought, what would having partially powered no tourqe rotors allow you to do performance-wise? Is there any benefit to letting them run throughout the flight?
 
It seems HILLBERG is thinking at this one! :D

https://www.youtube.com/watch?v=lnviOrV5zWY

When I had the fuel cell made for the Mouse(1990) at fuel safe I met a Hiller engineer who was involved in the Hornet project (he's the tall skinny guy blond hair)

Lots of neat stories from Frank, Hiller had some interesting ideas too bad they mostly where impractical.

As for the Djinn the 36 foot rotor lifted two as the Bell 206 had a 33 1/2 foot rotor lifted 5 plus bags and burned less fuel.

As for the ring of fire several jet tips will do it, Had an Eagle kit with jet tips at corona in the 1980s seems a fuel line ruptured on one blade and a fire ball spun over head as the machine shook like a wet dog, the pilot was lucky got from a hover to the ground but being propane fueled it took a minute for everything to stop burning...left a big chunk of blade burned away ...fun times for all.
 
Last edited:
....
As for the Djinn the 36 foot rotor lifted two as the Bell 206 had a 33 1/2 foot rotor lifted 5 plus bags and burned less fuel.

The Bell has an engine which is twice as powerfull as the Djinn's engine... How can it burn less fuel?
 
That project is now called Pegasus , the one you saw in the video was wrecked at Camarillo Ca,(slung a blade at a hover) the drive system and rotors replaced (rebuilt repaired etc) seen the same guys named Hondo.
It now has a Royorway style fuselage the rotor span still says low power efficiency,
as a home builder you're better off using the drive system of a Honda Goldwing motorcycle and a normally aspirated power plant.
18 foot rotor motorcycle rear drive turned 90* as main gearbox belt drive from engine (H-269 or R-22 style) simple boom skid gear like a Mariano Mc 1.

all off the shelf no special blades, ducts, compressors, and with a tail rotor you have better results in heading with power off landings ( a fin in the breeze just don't cut it)

standard conformity more compact known qualities
 
The Bell has an engine which is twice as powerfull as the Djinn's engine... How can it burn less fuel?

more efficient drive system. 270 hp in an Allison 250 c 20 burns 22 gph at max torque.

Air ejected at a tip going 300 mph needs more push to do the same work done.

or think of riding in a speed boat going 50 knots and think how big a hose you would need and the pressure and volume needed to go faster...
 
Hopefully you can help me understand these questions which arise from reading attaboykf's post here.

The Robinson R22 has a 92kw engine. How much power would electric ducted fans placed on the tips require to deliver the same performance? My guesstimate is around 30kw total, which would make tip jets more efficient.

The Hiller YH-32 Hornet is powered by 2 × Hiller 8RJ2B ramjet engines, 40 lbf (0.18 kN) thrust each equivalent to 45 hp (33.6 kW).

A DS-130-DIA HST (152mm) uses 12kw to deliver 175N. What sort of performance would a tip jet built with these have?

If you put a 30kw tip jet on a wind turbine, how much power could be produced at the shaft?
Would it be possible to increase the power of output of a bicycle by using this fulcrum effect?
 
The Robinson R22 has a 92kw engine. How much power would electric ducted fans placed on the tips require to deliver the same performance? My guesstimate is around 30kw total, which would make tip jets more efficient.
First ask yourself how fast your electric duct fan would fly straight and level .... lets say 100 mph.

But the tip of a rotor blade travels about 400 mph ... so your setup would create only drag and no thrust beyond 100 mph.

Be cautious when read the professor Foa article ... he is talking about rockets ... not tip jets as we know them. Big difference.
 
Top