Some updated stats: I edited my spreadsheets to include the minor changes (AR's flying sofa

, etc), reduced the drag for a stopped prop slightly (57" rather than 60" diameter) and we can also use the single-engine prop/75 HP VW engine thrust figures Jan provided (POST 270) to estimate single-engine climb performance.

All figures below are for single engine performance (thrust from one engine, drag from one stopped propeller).

If the engines/props behave like this and the if drag numbers are close, an engine failure won't be a major event, at least from a climb performance standpoint. And, if we use an engine that truly provides more than 70 HP at SL standard day conditions (i.e. if the Revmaster does make 85 HP/80HP continuous), then the climb performance below might be about what we'd expect at 3000 MSL or so.

**Pops**: (140 sq' wing, 34' span, single-strut metal wing, 2 place tandem tube fuselage with AL or CF skins)

.....Zero-lift Effective Flat Plate Drag (EFPD), normal: 3.4 sq ft

.....Zero-lift EFPD, one stopped prop: 4.4 sq ft

.....70 Kts SL: Single engine thrust available: 205 lbs (Jan's post #270) (note: this is for a

__70__ HP engine)

.....70 Kts SL: Single engine zero-lift drag: 70 lbs

.....70 Kts SL: Induced drag at 1500 lbs:47 lbs .....1600 lbs: 53 lbs .......1700 lbs: 60 lbs

.....70 Kts SL: Total Drag...........1500 lbs:117 lbs ...1600 lbs 123 lbs.....1700 lbs: 130 lbs

Excess Thrust avl for SE climb:...1500 lbs: 88 lbs .1600 lbs: 82 lbs ...1700 lbs: 75 lbs

Estimated single-engine ROC 1500 lbs : 411 FPM......1600 lbs: 359 FPM.....1700 lbs: 309 FPM

**Autoreply**: (126 sq' wing, 45' span, cantilever wing, all composite, 4 place cabin)

.....Zero-lift Effective Flat Plate Drag (EFPD), normal: 2.9 sq ft

.....Zero-lift EFPD, one stopped prop: 3.8 sq ft

.....70 Kts SL: Single engine thrust available: 205 lbs (Jan's post #270) (note: this is for a

__70__ HP engine)

.....70 Kts SL: Single engine zero-lift drag: 61 lbs

.....70 Kts SL: Induced drag at 1500 lbs: 35 lbs..1600 lbs: 40 lbs ..1700 lbs: 45 lbs….1800 lbs: 51 lbs

.....70 Kts SL: Total Drag.........1500 lbs: 96 lbs..1600 lbs: 101 lbs. 1700 lbs: 106 lbs ..1800 lbs: 111 lbs

Excess Thrust avail for SE climb:.1500 lbs 109 lbs..1600 lbs: 104 lbs ...1700 lbs: 99 lbs 1800 lbs: 94 lbs

Estimated single-engine ROC (FPM) 1500 lbs: 509 ...1600 lbs: 455 …..1700 lbs: 408 ….1800 lbs: 362

Comment: Too much motor? Consider 2 x 1/2VWs instead?

**Vigilant1**: (126 sq' wing, 35' span, cantilever composite wing, 2 place tandem tube fuselage)

.....Zero-lift Effective Flat Plate Drag (EFPD), normal: 3.0

.....Zero-lift EFPD, one stopped prop: 3.9

.....70 Kts SL: Single engine thrust available: 205 lbs (Jan's post #270) (note: this is for a

__70__ HP engine)

.....70 Kts SL: Single engine zero-lift drag: 63 lbs

.....70 Kts SL: Induced drag at 1500 lbs: 47 lbs ....1600 lbs: 53 lbs …..1700 lbs: 60 lbs

.....70 Kts SL: Total Drag..… ...1500 lbs: 110 lbs .1600 lbs: 116 lbs…..1700 lbs: 123 lbs

Excess Thrust for avail for SE climb:1500 lbs: 95 lbs...1600 lbs: 89 lbs ..1700 lbs 82 lbs

Estimated single-engine ROC 1500 lbs: 443 FPM ...1600 lbs: 389 FPM...1700 lbs: 338 FPM

Regards,

Mark