Vx or Vy climbout to increase chances of return to field?

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uncreative

Pre-takeoff checklist
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Uncreative
Departing from a field that doesn't have a lot of attractive options in case of engine failure on climbout, is it best to climb at Vx or Vy to provide the best position to get back to the field?
 
I was always taught to climb out at Vy to get the most altitude quick in case your engine dies, you'd have more options, including turning back.
 
Agreed. Vx is for terrain avoidance.
 
This was hashed out a year or so ago. I believe the answer was Vy for puny spam cans, and zoom climbs for RVs...
 
Depends. Vy takes you farther from the field for the given increase in altitude. Vx puts you closer to the critical angle of attack (i.e. risk of stall)--particularly if you start aggressively maneuvering to return to the field.

Generally speaking though, Vy is preferred once obstructions are cleared.
 
With many light aircraft, the problem is being too far from the field to make it back. In that case, Vx improves matters by causing you to be closer to the field when the engine quits. You might also consider climbing in the pattern instead of straight put. However, I've been told that it's not wise to attempt a turnback unless you have received training on the maneuver from an instructor who is knowledgeable and experienced in it, and have practiced it at a safe altitude (i.e., well above pattern altitude) enough to develop and maintain proficiency in it.
 
Like any maneuver the only way you can know what it's like or what condition you'd prefer in a situation is to practice it in the most realistic conditions you're comfortable with. How much flap? How steep a turn? Those are better questions. experimenting with a slow climb/pull power/make a 180* turn in different configurations and see which nets the least altitude loss.

I don't use Vx unless it's necessary. To lose an engine at Vx and maintain airspeed would be more difficult than Vy. My own emergency turn speed is higher than Vx. To lower the nose and accelerate by going downhill prior to starting this emergency turn doesn't sound like a good way to set it up.
 
Vy + remaining in the pattern until a sufficient altitude has been gained.
This will allow you to gain the most altitude in the shortest amount of time, keep you close to the runway and also provides better engine cooling due to the higher airspeed.
 
Palmpilot said:
With many light aircraft, the problem is being too far from the field to make it back. In that case, Vx improves matters by causing you to be closer to the field when the engine quits. You might also consider climbing in the pattern instead of straight put. However, I've been told that it's not wise to attempt a turnback unless you have received training on the maneuver from an instructor who is knowledgeable and experienced in it, and have practiced it at a safe altitude (i.e., well above pattern altitude) enough to develop and maintain proficiency in it.
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With many light aircraft, engine cooling is a problem for extended climbs at Vx, so your engine is more likely to fail….

The 270 departure would be a better option for airports that are truly limited in options. Not that I've seen many of those. Even RHV, which is in the middle of the city, has an open field on the other side of the mall, a big park under the right downwind for 31R, a parallel wide surface highway with traffic that isn't TOO bad, and two interstate highways. People seem to land on Capitol Expressway around once a year….
 
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Takeoff and initial climb cooling is best provided by full throttle pushing fuel through those cylinders. Vx or Vy makes little difference for the durations in question.

For wheel ops to the north from Lake Hood I have a 1200' ceiling to cross 3+ miles of ocean water. I try to get as much altitude as I can prior to crossing the shoreline. I find Vy to be much more effective. By that time I'm at 800-900' even when loaded on a warm day. At that point I'd turn back. No doubt about it. That being the case I want to best opportunity to be successful and that begins with appropriate airspeed to execute the turn. Off my cabin strip there's no scenario that would justify a 180* turn. The other options aren't great but they're better than attempting a 180 to a narrow short LZ that's surrounded by obstacles. Consider your own conditions and options and prepare for them.
 
In the Yak community, except for formation takeoffs we climb out at Vx since altitude is more important than initial energy state at possible engine failure given the high-drag nature of our birds.

I have yet to practice the impossible turn in the Yak and as such would not attempt it right now (as hard as that decision might be), but have practiced it in many other planes and once you know what your specific plane requires under specific conditions (weights mostly) it CAN be done.

Specific to the Yak and in San Diego, cooling is not usually a problem during initial climb with the gills wide open, and we typically reduce power early, I usually pull manifold pressure back to 800mm and prop to 82% at about 500' which is still close to 300 or so HP I think. At that setting I can maintain ~1,000 FPM.

Formation takeoff is something else altogether though.

'Gimp
 
Stewartb said:
Takeoff and initial climb cooling is best provided by full throttle pushing fuel through those cylinders. Vx or Vy makes little difference for the durations in question.
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Only if you're full rich.

DA above 3000 in Cessna singles calls for leaning at run-up. It's not hard in summer to get above 3000 DA even at low altitude airports. Well, maybe it is in Alaska…. If I go to South County (E16) as planned today, the forecasted DA is over 3000. But I'll probably go to the coast instead. Too FN hot down there.

KTRK used to call for Vx climbs for noise abatement. It doesn't anymore; that was stupid. Today, the DA will probably top 10,000.
 
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MAKG1 said:
With many light aircraft, engine cooling is a problem for extended climbs at Vx, so your engine is more likely to fail….
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When I said "many," I was thinking of Cessna 172s. :)

...The 270 departure would be a better option for airports that are truly limited in options...
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Sounds like that could be a good plan.
 
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By the way, one issue that many people fail to consider is whether the glide angle exceeds the climb angle for the particular aircraft and wind conditions. If it does, then the best way to deal with hostile terrain around the airport might be to climb overhead the field.
 
Neither..... Pilots get all wrapped around the axel on numbers. If your worried about it, lift off and accelerate to a speed well above vx or y in a gentle climb the aircraft will choose its rate.

If it fails before the end of the long skinny thing you just left, put it back there. If you are beyond it, you have airspeed and now is a good time to figure out where you are going to crash it it.

Pointing it at the sky under vx or vy is not in your best interests.
 
uncreative said:
Departing from a field that doesn't have a lot of attractive options in case of engine failure on climbout, is it best to climb at Vx or Vy to provide the best position to get back to the field?
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Vx gets you highest in the least distance, so it requires the least glide back to the runway allowing the most altitude lost in the 'impossible turn'. You would really have to determine it for each runway length.
 
VY you should have a good idea of the possible off airport landing sites,at the airports you use most of the time.
 
uncreative said:
Departing from a field that doesn't have a lot of attractive options in case of engine failure on climbout, is it best to climb at Vx or Vy to provide the best position to get back to the field?
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Consider the wind and the equipment. If you climb a slick plane at Vx into a stiff headwind and then turn back you could end up overshooting the runway.
 
I think in most cases elevation gain over time (Vy) is more valuable than elevation gain over distance (Vx).
 
Sac Arrow said:
I think in most cases elevation gain over time (Vy) is more valuable than elevation gain over distance (Vx).
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It depends on the length of the runway vs runway required. The closer those numbers are together, the more it favors Vx, the further the more it favors Vy.
 
Henning said:
It depends on the length of the runway vs runway required. The closer those numbers are together, the more it favors Vx, the further the more it favors Vy.
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Can you come up with any airports where depending on Vx really is necessary?

Everyone likes to freak out over KEMT, but it looks to me like it has one of LA's infamous paved concrete almost-empty "rivers" right next to it. That looks like a much better option than attempting a turn-back at low altitude, even if you have to dodge a bridge or two.
 
Vx. Winds are always crossing from the left. If light I may fly in ground effect to build speed and use that for turbulence penetration at the treetops. No turning back here.

The idea that Vx and Vy net the same altitudes in the same amount of time is incorrect. How incorrect is specific to the airplane, the load, and the weather.
 

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MAKG1 said:
Can you come up with any airports where depending on Vx really is necessary?

Everyone likes to freak out over KEMT, but it looks to me like it has one of LA's infamous paved concrete almost-empty "rivers" right next to it. That looks like a much better option than attempting a turn-back at low altitude, even if you have to dodge a bridge or two.
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Airport runway? Not really, some off airport strips, yes.
 
Stewartb said:
Vx. Winds are always crossing from the left. If light I may fly in ground effect to build speed and use that for turbulence penetration at the treetops. No turning back here.

The idea that Vx and Vy net the same altitudes in the same amount of time is incorrect. How incorrect is specific to the airplane, the load, and the weather.
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Wouldn't Vx always yield less altitude over time than Vy?
 
It depends if Vx allows you to miss an obstacle where Vy doesn't. :eek:

No, seriously, I suspect there are conditions where initial time to climb rates are pretty similar but factor in different planes, loads, and temperatures and there will be variations. What I referred to, and stated poorly, was that in many cases using Vy may get enough extra altitude to make the distance from airport or proximity to other alternative LZ sites a better option. As in most internet topics, the answer to the original question is "it depends". All the comments that follow demonstrate that.
 
I climb out on the blue dot and it scares the crap out of seasoned pilots sometimes.

I had no idea the wagon could pull that until I installed the AOA.


AOA3000HK.jpg
 
FastEddieB said:
You do.

Vx increases with altitude while Vy decreases. They meet at the absolute ceiling of the aircraft, at which point no speed will result in a climb.
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Well, as long as you use absolute value for Vx and Vy, not defined value, since defined value is at gross weight.
 
I would vote for Vy. Using a C172 as an example, when at Vy (72-74) the speed is higher than Vg (68) so you would need to slow down (pull back on yoke and maintain altitude) to get to get to that speed. With a Vx climb out, you would need to aggressively lower the nose to gain airspeed to get to Vg, resulting in a net loss of altitude.
 
nimdabew said:
I would vote for Vy. Using a C172 as an example, when at Vy (72-74) the speed is higher than Vg (68) so you would need to slow down (pull back on yoke and maintain altitude) to get to get to that speed. With a Vx climb out, you would need to aggressively lower the nose to gain airspeed to get to Vg, resulting in a net loss of altitude.
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You will have to lower the nose (actually, if trimmed correctly it will do it itself) either way as soon as the engine dies and you revert to gravity for your energy supply.
 
I climb at Vx until clear of obstacles, then lower the nose to Vy. Since it's now summer in the South, I climb a little at Vy then lower the nose a little more to keep engine temps believable.
 
I've cleared the trees by 20 feet leaving 06 at VKX. I didn't like how that felt. I sure wouldn't of wanted to leave the nose pointed at the trees any longer to get to Vy.
 
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