0160

Item 0160

OTHER: Helicopter - Outside - Single (1-seat) - Helicycle

Other Web Sites:

Latest Info (January 31, 2003):

Helicycle is going with the T-62-T32 Solar turbine engine. They have taken delivery of about 50 used ones, which they will inspect and partially rebuild. There's an article on this in the Feb/03 issue of Kitplanes.

There is also a movie of the turbine version flying at;- www.helicycle.com/dougschwochert/helicycle.WMV

Rotor - Hub:

"The lead/lag adjustment is typically Bell Jet Ranger in style. In fact, the Helicycle rotor hub was designed to be a look alike and functional sibling of the classic high quality Jet Ranger hub."

The pitch bearing is elastomeric. For general information see:- Rotor Hub - Pitch Bearing - Elastomeric

Power Train - Primary Reduction:

B.J. Schramm feels that the engine firing impulses are isolated from the transmission by the use of V-belts (180º / firing). He also feels that a cog type belt is too stiff. Note:- This is valid for engines with relatively few firings per revolution. A V-belt primary reduction is even used on the 6 cylinder 4-stroke Robinson R-22 (120º / firing)

The following data is from the helicopter at Arlington (July/2001).

	Belts:	Super HC ~ 3V 560 ~ Gates (Vextra?)
	Quantity:	5
	Sheave pitch diameters:	Approximately 5" and 11"
	Tensioner:	Approximatly 4" dia. flat face pulley on back of belts on T-2 side.
	Ctr. to Ctr.	18" approximately

Rough calculation using the above data and Morse 3VX Gripnotch caculations:

Input

Max. HP is 70 A guess

Max. RPM is 6000. A guess

Max. belt speed is 6000 * pi * 5" = 7857 fpm.

Design selection using 3VX Gripnotch belt Drive

(Calculations from Morse catalog. p. G5)

1/ 3VX [This is the belt size that the Helicycle is using.]

2/ Overload service factor of 1.1.

Design HP = 70 * 1.1 = 77

3/ d = 5" diameter

D = 11" diameter

11 / 5 = 2.2:1

4/ 6000 rpm

5/ 5" diameter at 6000 rpm is about 17 hp

6/ 88 / 17 = 5.2 sheaves

7/ Of no current interest

8/ A/ 17 hp + .85 hp = 17.85 hp

B/ 17.85 hp * .89 = 15.88 hp.

C/ Loss in Arc of Contact = (D - d) * 57 / C = 23.65

Correction Factor = .94

15.88 * .94 = 15 hp.

15 hp * 5 grooves = 75 hp. ~ Service Factor of 0.974 (Note: the Gates Super HC belts may have a better rating then the Morse 3VX Gripnotch)

The use of the V-belts for soft-start may be considered somewhat detrimental to belt life, but Robinson does it also.

Power Train - Secondary Reduction:

Helicycle has a spiral bevel gear secondary reduction, with tapered Timken bearings.

The secondary reduction gear case is a 356-T6 aluminum casting.

Equipped with oil cooler, filter and pump.

Equipped with oil sight gauge, oil temperature gauge and optional chip light.

Engine:

July 15, 2001 ~ It appears that the Helicycle will be using the Rotax 700cc and 800cc non-aircraft engines. One, and probably both, of these engines have single ignition systems. Schramm said that these engines come with a low-friction piston coating, which Rotax does not used on their aircraft engines. These engines are for a Sea-Doo/Ski-Doo where the cooling is coming from cool ocean/lake water or from cold winter air. The Helicycle appears to have a good cooling system. The engines have reed valves and improved crankshaft bearings. The intent is to use a higher oil to gas ratio then standard.

Schramm also says "Possibly one of the most costly lessons was the necessity of a separate production line for assembling the aviation engines, in order to maintain a higher standard of quality control." This implies that the selected engine will not have the "higher standard of quality control" of their aircraft engines

The engine may be the weakest component on the helicopter. Rotax does not allow its certified 912 engine to be used on rotorcraft, so it would strongly appear that they will not accept any of their engines on rotorcraft. This may be the reason that Schramm and Rotax are not currently on speaking terms.

If or when autorotation is required;- The rotor blades have no twist and are asymmetrical which will help. Do not know what the rotor's inertia is.

The helicopter's gross weight is 770 lbs. Assuming a weight to power ratio of 11 lbs / hp. the engine's continuos power rating should be approximately 70 hp. The calculations show that 52 hp is required to hover out of ground effect at ISA.

Schramm's target is 70% continuous power. This will require the engine to be capable of providing a maximum horsepower of 70 */ 0.70 = 100 hp and this is probably the reason for the tuned exhaust.

At 70% continuous power the 700 cc. engine will operate at BMEP of 108 and the 800 cc. engine will operate at a BMEP of 95.

Outside web page: Salvation for the Two-stroke ~ by B.J. Schramm

From rec.aviation.rotorcraft ~ July 12, 2002 ~ Hyperbole from a magazine article

Four Stroke Helicycle Debuts at Arlington 2002

Coming to the realization that the market was going to dictate what they wanted to fly in the Helicycle, powerplant-wise, Designer BJ Schramm has quickly shifted gears and delivered just what the flight surgeon ordered. The first Helicycle, powered by a Rotax 912 engine, is at Arlington 2002 and the installation looks good. While additional testing was needed to insure that the powertrain could take the added stress of the Rotax, Schramm is now satisfied that it can do the job. With one builder ship already in the air and a number of others hot on its heels, Helicycles will basically be available in three versions... with the Rotax 912S (the 100 hp version), a two-stroke Hirth and a turbine APU conversion (already flying in the case of the customer built ship previously mentioned).

The Rotax installation looks tight, fits aft and underneath the junction of the tail assembly and the fuselage, and does not detract from the rugged good looks of the bird. With a new lot of kits currently being built for the next batch of owners, the first batch is coming together under the watchful eye of Schramm, who is using these early adopters to help him bullet-proof the kit and the aircraft. Each early aircraft completion is getting his personal once-over before taking flight and the owners are getting Schramm's full attention as they come up with suggestions and data for him to incorporate in the final kit. More info (and, we hope, a flight test coming as soon as we can get BJ to look aside long enough for us to run off with the critter...).

Tuned Exhaust:

The Helicycle has a tuned exhaust and tuned input. This is similar to the Mini-500 PEP kit. To me, this is being done to increase the maximum power, which intern results in a higher maximum Break Mean Effective Pressure and a higher efficiency. If this increased available power were to be utilized, there will be a reduction in reliability. Perhaps Schramm's thinking is that tuning the engine and then derating it will increase reliability. He was talking about a 500 to 750 hour life.

Safety:

The rotor hub is at approximately 6'-6" elevation, because this is a very small helicopter. The blades can teeter down to around a 5'-9" elevation. The soft-start is engaged by activating a lever while standing outside the craft on the port side. Schramm says that the pilot, while engaging the rotor and inspecting the running power train, should be bent over with one hand kept one foot off the ground. The un-shrouded tail rotor is also an obvious danger. January 31, 2003 ~ It appears that the soft-start is now done from inside the cockpit.

Vibration:

It has been mentioned that the current Helicycle prototype has a two per rev vibration. Two of us. for the fun of it, not knowing which of the six possible types it could be, have looked at the craft and speculated, that it might be rotational about the longitudinal axis. This could be caused by the rotor's downwash striking the horizontal stabilizer, which is located on one side only. If the frequency is the same as that of the welded its 4130 steel tube tail framework then it will be self-exciting. This guess is somewhat supported by the Helicycle's use of a torsional isolator at the tail rotor's gearbox.

Miscellaneous Information:

Rotor Disk and Horsepower Calculations Note: My calculations show a collective pitch of 6.58º to hover whereas Schramm says 5.25º on his web site.

Price:

Around $30.000.00 US, c/w engine.

Compound:

Last Revised: March 16, 2009