Landing speeds/different engines

[RGlos]

I have often thought about the effects of bigger engines/prop combinations

on landing/approach speeds. I have flown a O-235 powered Long EZ for 23 years now. I have two props, a cruise and a climb. The cruise is 62 x 62.

 

When I fly the climb prop, I always have to add a few rpm on landing.. My idle is about 750 rpm. On final I fly at 80 Kts. Near the threshold, I'm down to 70 Kts and touch down usually at 60 kts. Naturally there are times when I land faser than this but in most cases this is typical.

 

With a bigger engine with the same idle rpm and with a bigger pitched prop, I can only imagine a faster landing speed or at least some difficulty slowing down.

 

So the questions is, what combination do you have and what are your performance numbers?

[Drew Swenson]

I assume that this statement

"When I fly the climb prop, I always have to add a few rpm on landing.. "

meant that you had to add power over idle to maintain your descent rate for the given speed.

 

I routinely flew out of 2000 ft strips with my 0320 Longez. With the O235, I was comfortable landing at a 2000 ft strip---but not taking off (needed to be somewhat light). The O32O got you off the ground pretty quick.

 

I flew very tight patterns with the Long---but that was with the board down, back at idle and rudders (original) deployed all the way to just before touchdown.

 

The extra installed wt and extra idle thrust should have a somewhat negative effect---but I did not measure it. The takeoff/climb effect is very noticable.

 

More or less, airplanes want to land at a certain AOA for that airframe. More weight on the same frame gives you higher airspeed for the given AOA. For the most part on our small airplanes, our landing weight is not really moving around that much, so we can more or less lock in a "landing speed." When you are dealing with airplanes that can vary thousands of lbs on landing, you need to calculate your landing speed based on weight (or use the AOA). With this being said, your plane's landing speed should be the same with a different engine---unless you are installing an engine that significantly shifts your landing gross weight.

[Marc Zeitlin]

I have often thought about the effects of bigger engines/prop combinations on landing/approach speeds.... With a bigger engine with the same idle rpm and with a bigger pitched prop, I can only imagine a faster landing speed or at least some difficulty slowing down.

A larger engine with a larger, higher pitched prop will produce more idle thrust. However, there's no reason (if the weight and CG of the aircraft are the same) that more thrust should cause you to have to land faster. All that's required to keep the approach path the same is more drag to balance the higher idle thrust. Remember:

 

L=W

 

and

 

D=T

 

in unaccelerated flight.

 

So, use your landing brake, use both rudders, and/or slip. Voila - same glide path, same approach speeds as with a smaller engine/prop combination.

 

You may need to use more brake on the ground, but that says nothing about the glide path. If folks are landing faster with larger engines, they don't need to.

[bigorneau]

I have an e-racer mk1 with V8 auto Land Rover engine 4.6 liters injection

max load is 930kg (2048 lb)

at this weight stall speed was tested around 62 to 65 knots

at load 820 kg i have tested stall speed at 55 knots

final speed at 80 knots

landing speed 70 knots

when i wish short landing distance i use hight incidence (15 to 20°)and speed mini 65knots with power at engine (2500 rpm) (propeller 1600 rpm)

my propeller is 65.36 inch diameter and 90.56 inch pitch two blades

down wind speed is 105 knots

best speed to climb is 100 to 110 knots

climb rate from 1500 to 2500 ft/mn

best speed to fly without engine is 105 knots (ratio 17 tested)

i can transmit more information if needed

my engine power is 165kw (225cv)

avgas100LL need between 20 liters to 30 liters (economic to full power)