1645

Item 1645

DESIGN: SynchroLite ~ Power Train (for 1 engine) - Assembly - Layout - Worm & Wormgears

Overall Objective:

To assimilate information on the possibility of acquiring an efficient worm & gear reducer, which would be used in the SynchroLite intermeshing helicopter.

This page is on a conventional worm & gear. See the links below for separate pages on the possibility of a Worm (w/balls) & Wormgears, or Worm and Gear (w/balls) reducer.

To produce an intermeshing helicopter that only requires a total of three gears for reduction and power transmission.

The helicopter would be powered by a single engine or a single electric motor. The SynchroLite is designed to be lightweight. The worm & wormgears may, hopefully, result in a further weight reduction.

The opposing lead-lag of the two rotors will put additional loading on the gearbox and its components. Allow for torsion in the shafts?

If the intent is to meet the Ultralight category and/ or use electric power, perhaps the 2-blade rotor with high twist might be better for lift/power than the 3-blade CVJ. However this will sacrifice improved controllability. ~ Will it? See 2-blade with hub spring &/or Offset teetering.

It may be possible to use a 7.5:1 ratio. This will provide better efficiency and allow for back driving, which will be essential during autorotation.

General Notes Related to the Complete Powertrain:

An obliquity angle of -10º combined with a conning angle of 4º gives the same clearance of the other hub as does an obliquity angle of -11º combined with a conning angle of 3º. This distance from pitch axis of the blade down to pitch axis at the center of the other rotor's hub is 5.22".

The above therefore make little difference to the advancing blade since the rotors are turning inside forward (breaststroke). The retreating blades, at the sides will be 2º higher, which is good.

In addition, the slow RRPM of the rotors mean that the default coning will be higher than normal, which is also good.

Seriously consider -9º obliquity angle, like UniCopter. This will reduce vertical center-to-center by about 1/2" form the above.

Current Concerns:

The durability of the worm appears to be too low.

Increasing the ratio causes the width of the gearbox to be greater.

This will involve; more bracing within the box and a heavier reducer.

If low durability will only affect the life of the gears then this MIGHT be OK.

Would an Envelope Worm Gearset increase the durability?

If a portion of the worm's tooth broke or seriously wore would an Envelope Worm Gearset result in outer portions of the worm tooth retaining synchronization?

Drawing:

Boston ~ 6 Diametral pitch, 30 tooth gear, Quad thread worm gives a center distance of 3.5" and a HP of approx. 9 HP per worm gear.

Perhaps this MIGHT NOT be OK if there is an exceptionally good lubricant, very good cooling and the shock from the engine seriously diminished. Note that both wormgears will be contributing to the heat of the common worm.

Preliminary Notes:

Ratio: A single reduction that will be somewhere between 7.5:1 and 9:1.

Have the worm integral with shaft. This is because;

It is more efficient than a separate worm and shaft.
A fan may be mounted on the shaft, if desired, or
A sheave to a sheave on a propeller shaft may be mounted, if desired. A V-belt drive may serve as a soft-start for the propeller.

Handing of worm & wormgear: The motor rotates CCW. The rotors rotate inside forward (breaststroke). The worm & wormgear will be left-hand.

Speed Limitation: Industrial worm gears are usually limited to 3600 RPM of worm or 6000 feet per minute rubbing velocity of worm. ~ source - Hamilton Gear

A flexible coupling would be located between the engine (or motor) and the gearbox.

An overrunning clutch will be located within or adjacent to the flexible coupling.

A horizontally-opposed engine, such as the Hirth F-30, should allow for a V-belt soft-start drive from the OD of the centrifugal clutch to a shaft to an aft propeller.

Autorotation: Synchronization is by back driving through a 7.5:1 ratio worm & wormgears.

Preliminary Power Train Criteria:
What is the efficiency by providing greater pitch combined with the efficiency loss by going to a greater (<10:1) GEAR REDUCTION?

Rotors: ⁺/_-600 rpm. 3-blade rotors with their smaller diameter have faster RRPM and greater control due to CVJ&HS.

Transmission: Ratio 7.5:1

Engine: ⁺/_-4,500 rpm

Power from engine at 4.500 rpm; Optional engine http://www.recpower.com/3502.htm, 62ft/bs @ 4750rpm

	Speed:		Power:		Torque:
	Ratio:		Loss:
Engine:	4500	rpm	51 ⁽¹⁾	hp	60 ft-lb ⁽²⁾	81 Nm
Worm & Gear	7.5:1	: 1	4	%
Rotor	600	rpm	49	hp	429 ft-lb⁽³⁾	582 Nm

From Hirth graph

Total for both wheels

Additional Notes:

To see how a conventional worm & gear reduction will work out, particularly if co-current improvements or subsequent improvements can be made.

Improvements such as:

Is there lower friction material that the wormgears can be made from. Material that may wear faster (Life) but has the required strength.
Coatings of the gear (or worm).
Special low friction lubricant.
There must also be very efficient cooling.

Double Enveloping Worm Gearset:

See; OTHER: Mechanical - Gear - Worm Drive ~ Enveloping

Efficiency:

OTHER: Mechanical - Gear - Worm Drive ~ Efficiency and Friction

Symbols, Terms and Definitions:

Terms and Definitions: with sketches.

DR Gears see section 'S' for link to symbols.

Machinery's Handbook25. Page 1980-3

OTHER: Mechanics - Definitions & Algorithms

Boston Gear: http://www.bostongear.com/pdf/gearology/chapter04.pdf

6 DP. 30 teeth, 7.5:1 ratio This information is Single Enveloping.

		⁽¹⁾
	p ⁽²⁾	0.5236
	P ⁽³⁾	6
	L	2.094"
	a	0.167"
	D_W	2.0"
	D_G	5.0"
	CD	3.5"
	h_T	0.360"
	h_T	0.360"
	d_r⁽⁴⁾	5.334"
	D_T⁽⁴⁾	5.334"
	γ	18º 43"
	Ratio	7.5:1
	D_O⁽⁴⁾	5.434"

Values based on Boston's pages 81 and calculations on page 146

Formula should be p = D_G * 3.1429 / teeth in gear ????

Formula should be P = teeth in gear / D_G ???

These values do not appear to be obtainable from the Boston book.

Efficiency:

The efficiency of a worm gear depends on the lead angle of the worm. The angle decreases with increasing ratio and worm pitch diameter. For maximum efficiency the ratio should be kept low.

To obtain ~ Lead angle of worm: (γ): Having ~ Pitch Diameter of worm (D) and the lead (L): Formula ~ γ = tan^-1 (L / (3.1416 * D))

f = coefficient of friction. For a bronze gear and hardened steel gear a coefficient of friction of .03/.05 may be assumed for estimated value only.

Efficiency = E = tanγ(1-f tanγ) / (f + tanγ)

Using a Diametral pitch of 6, 20 teeth (3.33" diameter). Worm with double thread. 10:1 ratio

For double the lead is 1.0472" and the lead angle (γ) is 9Ί 28'

Efficiency = E = (tanγ (1-f tanγ)) / (f + tanγ) = (0.1667 * (1 - 0.04 * 0.1667)) / (0.04 + 0.1667) = 64%

This is the above one but with lower friction of 0.02 [see chart below]. Using a Diametral pitch of 6, 20 teeth (3.33" diameter). Worm with double thread. 10:1 ratio

For double the lead is 1.0472" and the lead angle (γ) is 9Ί 28'

Efficiency = E = (tanγ (1-f tanγ)) / (f + tanγ) = (0.1667 * (1 - 0.02 * 0.1667)) / (0.02 + 0.1667) = 89%

Using a Diametral pitch of 6, 30 teeth 5.0" diameter). Worm with quad thread. 7.5:1 ratio

For quad the lead is 2.0944" and the lead angle (γ) is 18Ί 26'

Efficiency (coeff. of friction of 0.04) = E = (tanγ (1-f tanγ)) / (f + tanγ) = (0.3388 * (1 - 0.04 * 0.3388)) / (0.04 + 0.3388) = 89%

Efficiency (coeff. of friction of 0.03) = E = (tanγ (1-f tanγ)) / (f + tanγ) = (0.3388 * (1 - 0.03 * 0.3388)) / (0.03 + 0.3388) = 91%

Efficiency (coeff. of friction of 0.02) = E = (tanγ (1-f tanγ)) / (f + tanγ) = (0.3388 * (1 - 0.02 * 0.3388)) / (0.02 + 0.3388) = 94%

The following is too slow but it is done so as to see what the efficiency of a single thread will be:

Using a Diametral pitch of 6, 16 teeth 2.667" diameter). Worm with single thread. 16:1 ratio

For single the lead is 0.5236" and the lead angle (γ) is 4Ί 46'

Efficiency = E = (tanγ (1-f tanγ)) / (f + tanγ) = (0.0834 * (1 - 0.04 * 0.0834)) / (0.04 + 0.0834) = 59%

Note that the efficiency for the current SynchroLite with 1-engine power train (w/ V-belt) is 100 - 4.72 = 95.28. See; http://www.unicopter.com/SynchroLite_PowerTrainAccessForm_1.html This means a difference of 95.28 - 91 = 4.28%. 4.28% * 60 hp = 2.55 hp loss which equals approximately 2.55 * 10 lbs = 25 lbs of lift. The current weight for the transmission and synchro mechanism is 49 lbs. Looks good.

Information on Worm Gearing, that is not Specific to This Application:

Web Page on This Sight; OTHER: Mechanical - Gear - Worm Drive

Starts - Number of Threads in Worm (N_W)

Outside Information on Conventional Worm Gearing:

Maximum efficiency = tan( 45 - [friction angle = atan(μ)] / 2 ) / tan( 45 + [friction angle = atan(μ)] / 2 )

To see what a very low friction and optimal ratio will give for efficiency.

Teflon ~ Maximum efficiency = tan( 45 - 2.29 / 2 ) / tan( 45 + 2.29 / 2 ) = tan( 45 - 1.145 ) / tan( 45 + 1.145 ) =0.92%
Bronze ~ Maximum efficiency = tan( 45 - 9.09 / 2 ) / tan( 45 + 4.545 ) = tan( 45 - 4.545 ) / tan( 45 + 4.545 ) = 0.8527/1.1727 = 0.72%

Friction Coefficient from OTHER: Mechanical - Gear - Worm Drive ~ Efficiency and Friction

Current assumption:

Worm 1" diameter = 3.142" circumference.

At engine speed of 4,500 RPM = 20 ft/sec = 5.0 m/s

Gives a friction coefficient of 0.023.

OTHER: Mechanics - Safety Factor

Hamilton Gear:

This information is Single Enveloping.

- Dimensioning:

FORM: Hamilton Worm Gear Selection. Not yet.

Table F - 7-1

Checked	Symbols:		Boston:
		Ratio:	7.5 :1	7.5 :1	7.6 :1	7.5 :1	7.5 :1	7:4:1	7.5 :1
		Gear teeth & Worm starts :	30 & 4	30 & 4	38 & 5	45 & 6	30 & 4	37 & 5	30 & 4
		Diametral pitch: (nbr. of teeth in wormgear / pitch dia.)	6 DP:	6 DP:	6 DP:	6 DP:	5 DP:	5 DP:	4 DP:
	Ref only	Module pitches: (pitch dia. /nbr. of teeth in wormgear) times 25.4 [for answer in millimeters]	4.233 mm	4.233 mm	4.233 mm	4.233 mm	5.080 mm	5,080 mm	6.350 mm
	a	Addendum, inches (nominal) ⁽³⁾	0.157 ⁽²⁾	0.144	0.131	0.144	0.173	0.157	0.216
	c	Clearance, inches	?	0.026	xx	0.026	0.031	0.031	0.039
	C	Center distance, inches ⁽⁵⁾	3.5	3.172	3.842	4.686	3.787	4.486	4.698
	d	Nominal pitch diameter of worm, inches	2.000	1.345	1.347	1.871	1.580	1.580	1.902
	d_o	Outside diameter of worm, inches	2.334 ⁽¹⁾	1.633	1.609	2.159	1.926	1.894	2.334
	D	Pitch diameter (std.) of gear in central plane, inches	5.000 ⁽¹⁾	5.000	6.336	7.500	6.000	7.393	7.493
	D_o	Outside diameter of gear, Normal, inches	~	5.431	6.732	7.925	7.069	7.865	9.246
	D_oAlso	Outside diameter of gear, Maximum, inches	~	5.503	6.798	7.997	7.155	7.943	9.354
	D_t	Throat diameter of gear, inches	~	5.287	6.601	7.781	6.340	7.708	9.030
	F_e	Effective face width of gear, inches	1.000	0.879	xx	0.879	1.044	1.044
	f	Face width of worm, minimum, inches	2.5	2.585	xx	2.804	2.744		3.429
	h_k	Working depth, inches ⁽³⁾	~	0.288	0.262	0.288	0.345	0.314	0.432
	h_t	Whole depth (ref. addendum + dedendum), inches ⁽³⁾	~	0.314	0.288	0.314	0.377	0.345	0.471
	L	Lead, inches	2.096	2.096	2.620	3.144	2.513	3.140	3.140
	N_G	Number of teeth in gear	30	30	38	45	30	37	30
	N_W	Number of threads (starts) in worm	4	4	5	6	4	5	4
	P_n	Normal pitch of worm and gear, inches	0.470"	0.470"	0.470"	0.470"	0.544"		0.680"
	r_G	Gear throat gear radius, inches	~	0.528	0.543	0.791	0.617	0.633	0.735
	p_X	Axial pitch of worm, inches	0.524	0.524	0.524	0.524	0.628	0.628	0.785
	~	Circular pitch of wormgear. ⁽⁴⁾ Same value as axial pitch, inches. Here for definition only.	0.524	0.524	0.524	0.524	0.628	0.628	0.785
	λ	Lead angle of worm and helix angle of gear, degrees	18.43º ⁽¹⁾	26.37º	31.75º	28.13º	26.84º	32.32º	27.71º
	Φ	Normal pressure angle of worm, degrees ⁽³⁾	14.50º ⁽¹⁾	25º	30º	25º	25º	30º	25º

Boston's values.

Hamilton calculation on Boston value on page 81

Hamilton Table F-8-1; except for Boston column.

Hamilton Page K-9; except for Boston column.

This is the distance between 1 wormgear and the worm. The center distance between the 2 wormgears will be slightly less than twice this value.

Table F - 9-1 ~ Worm Dimensions:

Checked	Dimension:	Symbol:	Formula:	6 DP: Boston:	6 DP: 4-start	6 DP: 5-start	6 DP: 6-start	5 DP: 4-start	5 DP: 5-start	4 DP: 4-start
	Lead,	L	N_w p_X*	2.094"	2.096"	2.620"	3.144	2.513	3.140	3.140
	Pitch diameter (nominal) approx.	d	0.45 (C^.875)* \| ⁸√C⁷\|	2	1.345	1.347	1.871	1.580	1.580	1.902
	Pitch diameter (nominal)	d	Specified	2.000	1.345	xx	1.871	1.580	1.580	1.902
	Outside Diameter:	d_o	d + 2a	2.334	1.633	1.609	2.159	1.926	1.894	2.334
	Minimum Face:	f	4 root((D * a)/ 2)*	2.5"	2.585"	xx"	2.804"	2.744"		3.429
	Lead angle:	λ	tan^-1 (L /( π d)) ⁽¹⁾*	18º.26' ⁽¹⁾	26.36º	31.75º	28.13º	26.84º	32.32º	27.71º
	Normal Pitch:	p_n	p_X cos(λ)*	0.470"	0.470"	0.470"	0.470"	0.544"		0.680"
	Normal pressure angle:	Φ_n	See table F - 8-1	14.50º ⁽¹⁾	25º	30º	25º	25º	30º	25º

(1) Trigonometry ~ Inverse tangent function, tan ^-1 or atn

Table F - 9-2 ~ Gear Dimensions:

Checked	Dimension:	Symbol:	Formula:	6 DP: Boston:	6 DP: 4-start	6 DP: 5-start	6 DP: 6-start	5 DP: 4-start	5 DP: 5-start	4 DP: 4-start
	Pitch diameter (standard)	D	(N_G p_X ) / π*	5.000"	5.000"	6.336"	7.500"	6.000"	7.393"	7.493"
	Throat diameter	D_t	2 C - d + 2 * a*	~	5.287"	6.601"	7.781"	6.340"	7.708"	7.925"
	Outside diameter	D_o	Normal = D_t + a Maximum = D_t +1.5 a*	~ ~	5.431" 5.503"	6.732" 6.798"	7.925" 7.997"	6.513" 6.599"	7.865" 7.943"	8.141" 8.249"
	Throat Form Radius	r_G	(d - 2 a) /2*	~	0.51"	0.543"	0.551"	0.633"	0.633"	0.755"
	Effective Face:	F_e	root( (d + h_k )² - d²)	1.000"	0.879"	0.880"	0.879"	1.044"	1.045"	1.284"

- Efficiency:

Rubbing velocity of the worm (feet per minute) = (π * pitch dia. of worm * Rpm or worm) / (12 * cosine of Lead Angle) = (3.14 * d * 4500) / (12 * cos(λ))

For ref only. For 6 DP Boston, 4-starts = (3.14 * 2 * 4500) / (12 * 0.950) = 2,479 fpm

For 6 DP, 4-starts = (3.14 * 1.345 * 4500) / (12 * 0.896) = 1,768 fpm

For 6 DP, 5-starts = (3.14 * 1.347 * 4500) / (12 * 0.850) = 1,866 fpm

For 6 DP, 6-starts = (3.14 * 1.871 * 4500) / (12 * 0.882) = 2,498 fpm

For 5 DP, 4-starts = (3.14 * 1.580 * 4500) / (12 * 0.892) = 2,086 fpm

For 5 DP, 5-starts = (3.14 * 1.580 * 4500) / (12 * 0.845) = 2,205 fpm

For 4 DP, 4-starts = (3.14 * 1.902 * 4500) / (12 * 0.885) = 2,531 fpm

________________________

Efficiency of Worm and Gear Sets in Percent: From Table F - 10-1

For ref only. For 6 DP Boston, 4-starts: factor η = 94.5,

For 6 DP, 4-starts: factor η = 95.25.

For 6 DP, 5-starts: factor η = 96.0

For 6 DP, 6-starts: factor η = 96.0

For 5 DP, 4-starts: factor η = 96.25

For 5 DP, 5-starts: factor η = 96.25

For 4 DP, 4-starts: factor η = 96.25.

- Horsepower Ratings: Note that the calculations below are based on the optimal materials etc and they do not take into account the extra activity on the worm due to its driving of 2 wormgears.

Durability Horsepower Rating:

Checked	Worm:		P_ac = (n_w s_ac * C_v * Z * p * D^1.8) / (1980 * η * m_G) =*
		6 DP: 4-start	(4,500 * 8,800 * .065 * 1.230 * 0.524 * 18.119) / (1980 * 95.25 * 7.5) = 21 HP
		6 DP: 5-start	(4,500 * 8,800 * .065 * 1.245 * 0.524 * 27.750) / (1980 * 96 * 7.6) = 32 HP
		6 DP: 6-start	(4,500 * 8,800 * .064 * 1.677 * 0.524 * 37.593) / (1980 * 96 * 7.5) = 59 HP
		5 DP: 4-start	(4,500 * 8,800 * .065 * 1.168 * 0.628 * 25.135) / (1980 * 96.25 * 7.5) = 33 HP
		5 DP: 5-start	(4,500 * 8,800 * .065 * 1.153 * 0.628 * 36.633) / (1980 * 96.25 * 7.4) = 48 HP
		4 DP: X-start	(4,500 * 8,800 *
	Gear:		P_ac = (n_w s_ac * C_v * Z * p * D^1.8) / (1980 * η * m_G) =*
		6 DP: 4-start	(4,500 * 2,200 * .133 * 1.235 * 0.524 * 18.119) / (1980 * 95.25 * 7.5) = 10.9 HP
		6 DP: 5-start	(4,500 * 2,200 * .127 * 1.240 * 0.524 * 19.913) / (1980 * 96 * 7.6) = 11 HP
		6 DP: 6-start
		5 DP: 4-start	(4,500 * 2,200 * .198 * 1.169 * 0.628 * 25.158) / (1980 * 96.25 * 7.5) = 25 HP
		5 DP: 5-start
		4 DP: X-start

Strength Horsepower Rating:

Checked	Worm:		P_at = (n_w s_at * K_v * p * F * R_r * D * Cos(λ)* / (1100 * η * m_G) =
		6 DP: 4-start	(4,500 * 50,000 * 0.15 * 0.524 * 0.879 * 1.066 * 5.000 * 0.896 / 1100 * 95.25 * 7.5 = 94 HP
		6 DP: 5-start	(4,500 * 50,000 * 0.15 * 0.524 * 0.880 * 1.069 * 6.336 * 0.850 / 1100 * 96 * 7.6 = 111 HP
		6 DP: 6-start
		5 DP: 4-start	(4,500 * 50,000 * 0.15 * 0.628 * 1.044 * 1.071 * 6.000 * 0.892 / 1100 * 96.25 * 7.5 = 160 HP
		5 DP: 5-start	(4,500 * 50,000 * 0.15
		4 DP: X-start	(4,500 * 50,000 * 0.15
	Gear:		P_at = (n_w s_at * K_v * p * F * R_r * D * Cos(λ)* / (1100 * η * m_G) =
		6 DP: 4-start	(4,500 * 10,000 * 0.29 * 0.524 * 0.879 * 1.066 * 5.000 * 0.896 / 1100 * 95.25 * 7.5 = 36 HP
		6 DP: 5-start	(4,500 * 10,000 * 0.29 * 0.524 * 0.880 * 1.066 * 6.336 * 0.850 / 1100 * 96 * 7.6 = 43 HP
		6 DP: 6-start
		5 DP: 4-start	(4,500 * 10,000 * 0.29 * 0.628 * 1.044 * 1.071 * 6.000 * 0.892 / 1100 * 96.25 * 7.5 = 62 HP
		5 DP: 5-start
		4 DP: X-start

- Weight:

The following weights are rough approximations, for now.

Carbon Steel; 0.2835 lb per sq-in.

Bronze: 0.3171 lb per sq-ft.

Checked	Hamilton Gear Specs:	Worm:	Wormgear: ⁽¹⁾	Set of 3 gears:
	6 DP: 4-start ~ 30 & 4	1.6" dia * 5.5" = 11.1"³ = 3.1 lbs	5.5" dia * 0.9" = 21.4"³ = 6.9 lbs	17 lbs ⁽¹⁾
	6 DP: 5-start ~ 38 & 6	1.6" dia * 6.8" = 13.7"³ = 3.9 lbs	6.8" dia * 0.9" = 32.7"³ = 10.5lbs	25 lbs ⁽¹⁾
	6 DP: 6-start ~ 45 & 6	2.2" dia * 8.0" = 30.4"³ = 8.6 lbs	8.0" dia * 0.9" = 45.3"³ = 14.5 lbs	38 lbs ⁽¹⁾
	5 DP: 4-start ~ 30 & 4	1.9" dia * 7.2" = 20.4"³ = 5.8 lbs	7.2" dia * 1.0" = 40.1"³ = 12.9 lbs	32 lbs ⁽¹⁾
	5 DP: 5-start ~ 37 & 5	1.9" dia * 7.92" = 22.5"³ = 6.4 lbs	7.9" dia * 1.0" = 49.0"³ = 15.7 lbs	38 lbs ⁽¹⁾
	4 DP: X-start ~ 30 & 4	2.3" dia * 9.3" = 38.7"³ = 11.0 lbs	9.3" dia * 1.3" = 88.3"³ = 28.3 lbs	68 lbs ⁽¹⁾
	Mod:

(1) Note that the wormgears can have quit a bit of meat cut off them.

Consider Adding Teflon to the Oil:

ApNano Materials, Inc. from Rick

Interflon Fin Gear

Sizing of Worm and Gear;

Axial Module Worm Gears.

Hard copy of Hamilton Book.

Books;

The Theory and Practice of Worm Gear Drives

Other Components of Gearbox Etc:

See for example etc.

DESIGN: SynchroLite ~ Power Train - Rotor-Synchro - Layout

Housing:

An upper casting will contain the bearings for the mast and the attachment lug to the fuselage. The lower portion may consist of two halves, which might be identical except LH & RH, The left hand one has a plug where the input shaft is on the right hand one and this allows for a future PTO. ???

SynchroLite ~ Power Train (for 1 engine) - Housing

Bearing:

Ref. DESIGN: SynchroLite ~ Power Train - 1 Engine - Bearing - Selection Process, for Assy Item 1316 -- 2 Gear Sets & 1 Belt -- Idea 10

Lubrication:

The worm has the engine at one end, but the other end is available for oil pump &/or fan.

Cooling and Weight Reduction:

Consider an axial bore along the centerline of the worm.

Related Power-Train Items:

The following will eventually be moved to their own page or an existing page

Gears:

DESIGN: SynchroLite ~ Power Train (for 1 engine) - Reduction Primary - for Assembly 1645

Clutch(s):
Will a centrifugal clutch serve both the overrunning and soft-start?

It appears that the multi-engine Gen H-4 has centrifugal clutches but not overrunning (freewheeling) clutches. The Mosquito has both.

Can it also serve (or be modified to serve) as the flexible coupling?

The overrunning clutch may be necessary due to the situation where the rotor wants to turn a 100% RPM when the motor is turning at a slower speed but one that is above the centrifugal clutches engagement speed. In this situation the craft may operate satisfactorily but prolonged operations in this situation may eventually wear the clutch down and/or generate excessive heat.

- Soft Start:

A clutch will be required so that the engine can be started without having to turn the rotors.

Soft-Start:

BUY: PT - Clutch - Soft-Start - Centrifugal - SMC Axle Clutch

http://www.noramclutch.com/CLUTCHES/trilobe.html

http://www.compactradialengines.com/rz2.html

- Overrunning (freewheeling):

The overrunning clutch is to be located between the motor and the gearbox. The torque is ??? ft-lb.

This table was copied over and may not be applicable.

		Consider 2 Warner CSK 35 (Item 0568), Max. torque 207 ft-lb. Sprag. C/w brgs, 0.66 lbs.
		Consider Warner CSK 40, (Item 0741) Max. torque 384 ft-lb. Sprag. C/w brgs?, 1.10 lbs. This weighs more but it means less material in adjoining items.
		Consider 2 Marland-RINGSPANN R206 (Item 0524), Max. torque 195 ft-lb. No brgs. Keyway
		Consider Marland-RINGSPANN R208 (Item 0141), Max. torque 450 ft-lb. No brgs. Keyway
		http://www.stieber.de/products/gfkgb.html
		Look into the other ones mentioned on the line below

For additional information see: SynchroLite ~ Power Train (for 2-engines) - Overrunning Clutch Overrunning Clutch:

Power Source:

Potential Engine:

Hirth 3701:

http://www.hirth-engines.de/english/index.htm

A two-cylinder [Zanzottera MZ 202] [Hirth 2706, 65 hp] might be better since the intermeshing configuration should require less power than the single+tail and the longitudinal balance of the SynchroLite should be better.