Runup Parameters

[GrinchF16]

I’ve tried searching but no love. I have a RV7A with an O360 and a fixed pitch prop. If you have a similar setup, I’d like your techniques for takeoff:

Flaps/No Flaps for T/O
Runup check - Min RPM, min airspeed at a set distance, etc
Rotate Speed
Initial Climb Speed
Altitude/Criteria for Impossible Turn
Altitude for transition to Climb Speed

I know opinions are like…. Well, arm pits…. But I am interested in what folks are doing. I’ll put all your ideas in my clue-bag, shake it up real good, what stays in the bag will probably be good stuff!

Thanks

 

[simpkinsona]

Input

Hi, I have a 9A so not exactly the same but here’s my thoughts and techniques.

No flaps unless short/soft field.

Rotation at zero kts. The nose should be lifted as soon as possible. Hold a shallow nose up attitude until lift off (60ish knots). My nose comes off the ground pretty much as soon as power is in.

I accelerate in a shallow climb to 100 kts unless climbing over an obstacle. Climb speed is a compromise between cooling, climb rate, and forward progress.

After landing I hold the nose up until it won’t stay up (usually around 30 Kts).
If I have to roll a long way at speed, I’ll retract the flaps or add power to keep the nose up.

Short field or grass I’ll use 10-20 degrees flaps still lift the nose asap then rotate aggressively at 55kts. climb angle is impressive at about 60kts if needed.

Impossible turn varies wildly depending on circumstances. Best case for me is 300 feet at 100kts. Sometimes at higher weights and higher density altitudes there’s no safe turn around altitude.

-Andy

 

[GrinchF16]

Thanks Andy, great words!

 

[FireMedic_2009]

I would not lift the nose immediately in a strong crosswind. You could weathervane into the crosswind. Let the airspeed get to 40 kts or so to gain rudder authority to counteract the crosswind before lifting the nose up. As you build the speed up you could lighten the wt off the nose if the nose starts to shimmy. If the nose doesn’t shimmy then there’s no need to worry about getting the nose off the ground

 

[wawrzynskivp]

-7 Numbers

-7 with IO 390 CS prop and an AC package that brings empty weight up to 1286# MY CS prop may initially give me some better #s than your Fixed prop depending on how yours is pitched. But my higher Gross # will bring some of my performance experience down. -7 or -7A doesn't make much difference once the airplane is above 40 Kts.

No flaps, unless you have a rough runway and then only about 10-15 deg

Run up RPM for me is 1700. I get fast prop response and a solid Mag Drop.

Rotation is more of a feel. With low TO weights the numbers are changing really quickly and it all happens too fast to be focusing on Airspeed. That initial aerodynamic desire to fly and VX will be really close to the same thing.

Initial climb speed is a compromise between when it will leap off the ground and Vy unless there are obstacles. Vx is so nose high that I can't really see anything out front so that is reserved for when it is actually really needed. I use MPH so Vy comes out to be about 110. Once I get a solid lift I'll usually hold fwd stick and begin to accelerate in the climb. So that means I start out at about 70 MPH and hold fwd stick until VY. That takes all of about four seconds. From there I'll normally speed up to 120 MPH in the climb as that is the sweet spot for my cooling system and climb rate. For my package 120 MPH while faster than VY still provides a climb angle that exceeds glide angle all the way to about 12,000'. As a callout to VAC: Vx/Vy depend on weight and is better described as 53 units AoA and 32 units AoA respectively.

Impossible turn? I went out and did a lot of those turns with fuel shut off once the engine was fully broken in. For 5000' DA no wind, it is 650.' However this is a number you have to find out on your own. My Prop/Gov combo allows me full control down to 1200 RPM inflight. That coarse blade angle makes a HUGE difference. Your prop's specific pitch will make a big difference and most likely will still be producing meaningful thrust-drag delta at typical glide speeds while at idle. Don't believe that your no-power performance will be similar to an Idle Descent until you verify that. There are folks out there that will tell you the turn can be done in the 350' AGL range and while that may be true I wouldn't presume a number that low until you actually do it without ANY fuel going to your engine. In my package an idle descent is 150ft/min less than a true no power descent. BTW that 650' is for a 5000' runway. I need to add another 100' for each 1000' less than 5000' of runway unless the overrun is usable and doesn't have a Home Depot in it. (My aircraft will return 5000' upwind from the brake release point after a 270-90 from 650' AGL in a no-wind scenario) And no, you can't subtract from that 650' for runways longer than 5000'. If anyone asked me what a safe untested Turn Back altitude might be for a -7 / -7A I would offer NLT 800' AGL.

Alt to transition to a cruise climb really depends on where I am.

 

[Stevea]

I would not lift the nose immediately in a strong crosswind. You could weather vane into the crosswind. Let the airspeed get to 40 kts or so to gain rudder authority to counteract the crosswind before lifting the nose up.

Not in my experience. If the speed is high enough to lift the nose with the elevator, the rudder is effective enough to steer the nose. Also, the free castering nose wheel (no steering linkage) is not going to provide resistance to heading for the edge of the runway with a high crosswind component. Tapping the opposite brake pedal (if needed) and rudder use are what work.

I’m a graduate of the Mike Seager school of transition training. For the A models, Mike teaches soft field takeoff and landing techniques only. Basically, the nose wheel comes off the ground as soon as it can by starting with some back stick on the start of the takeoff roll. Once the nose wheel is off the ground, gradually move the stick forward to maintain the same pitch attitude as the speed builds. When the airplane is ready, it comes off the ground.

Back to the OP’s questions: using the soft field takeoff technique, there is no real “rotation speed”.

 

[WingsOnWheels]

As noted by other, get the nose light (don't have to be doing a wheelie, but take the load off) and then the aircraft will fly off when it is ready.

Back when I got my license in the good old Cessna I was taught to verify and call out "airspeed alive" and "Engine instruments Green". In the RV it is more like "Airspeed Aliv......and we're off".