Best angle climb speed Vx

One of the biggest things I took away from the EAA presentation on the "impossible turn" is that the runway length and winds are massive variables to consider. When departing from a short runway, you're going to be much further downrange from the departure end of the runway when the engine quits, all other things equal.

A head wind is naturally going to not only keep you close to the runway on departure but also help you get back there after you turn around compared to a no wind situation.

Academics vs practical application

I can’t contribute useful data as pertains to Vx/Vy numbers for the RVs. It seems thorough testing at min and max flight weights is in order as has been suggested.

As far as what is best?

This really comes down to risk management. In practice, the risk that needs to be mitigated varies from flight to flight. Sometimes the risk is terrain and lack of suitable landing sites such as a departure from a back country airport in Idaho. In other cases the highest risk is overheating and damaging your engine, which could increase the likelihood of a partial or sudden power loss during takeoff.

In my mind, risk cannot be eliminated. It can either be avoided, mitigated, or minimized.

The only way to truly avoid the risk is to not fly. For most of us that’s not acceptable.

There are many effective mitigation techniques: good maintenance, avoid flying when you can’t see the potential emergency landing site, avoid areas without landing sites. Etc..

As far as minimizing risk? To me this is mostly a function of time. A climb at best rate increases the margin between liftoff and the emergency landing zone in the shortest time. It seems to me, all things being equal, we should minimize the time of exposure to high risk activity inasmuch as possible. Vy to the pre-determined safe altitude unless there are obstacles or the engine is approaching cooling limits. After the safe altitude, the fly whatever makes your heart patter.

ChrisHodgens said:

There are the proud and the humble...... if you lose an engine less than 1000 agl, you have just the fields in front of you and that is it... I don’t care if you think you are the best pilot in the world and understand all the science that goes along with the Bernouli principles and l/d max and minimus,,etc,,,,,, If people are going to get on this forum and inform folks that losing an engine and returning to the field is nothing more than a simple wing over maneuver, that is just dangerous. I’ve seen 2 attempts to return to a field, both ended in fatalities. So let’s drop all the machismo and let’s inform the folks reading this what we were all taught at some point in our training. You shell one low, you have better had an off field landing site PICKED OUT BEFORE YOU TAXIIED OUT. I don’t ever post on this forum, but this subject and the “know it better than you” language that has been on now 4 pages screamed for someone to bring it back to reality.

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No need to be quite so dogmatic. What’s important is to know your aircraft and your capabilities.

There are certainly aircraft for which 1000’ is not enough altitude to return to the runway ... and others for which 200’ is excess (my glider for example). Furthermore if you can’t execute a 45 degree coordinated turn while gliding at about 1.5 Vs without stalling, you should definitely plan to fly *any* aircraft into the trees straight in front of you.

So emphatically yes, we are discussing this. In hope that more pilots will make better decisions based on the relevant facts and so that lives can be saved.

No need to listen if it offends your dogma.

Vac said:

Here are a few very good technical references regarding the aerodynamic considerations of turn back performance (these are referenced in Charlie's discussion on the topic in Sport Aviation and also linked on the EAA web site):

Should You Turnback? Discusses the optimal maneuver for a turnback after engine failure during take-off: http://www.nar-associates.com/technical-flying/impossible/possible.html

The Feasibility of Turn-back from a Low-Altitude During the Takeoff Climb-out Phase. The complete AIAA (American Institute of Aeronautics and Astronutics) paper that discusses a simulator experiment addressing the turnback after engine failure at low altitude (500 feet) during take-off problem:
http://www.nar-associates.com/technical-flying/jett/jett_wide_screen.pdf

The Possible "Impossible" Turn. This paper discusses the optimal maneuver for a turnback after engine failure during take-off. The paper is quite mathematical. However, any pilot can benefit from the discussion of the results and the graphs. Based on an AIAA (American Institute of Aeronautics and Astronutics) Journal of Aircraft paper of the same title (Vol. 32, pp. 392-397, 1995).http://www.nar-associates.com/technical-flying/impossible/impossible_wide_screen.pdf

Fly safe,

Vac
FlyONSPEED.org

Jerry, Vx occurs at Minimum Power Required alpha (i.e., the prop is producing maximum thrust); Vy starts at L/Dmax alpha, but since power increases with airspeed it actually varies a bit as Bob pointed out earlier in this thread. But using these two angles for initial takeoff works well from a practical stand point if you've got a system that provides accurate cuing.

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Vac,
Once again, excellent references.
Thanks,
Peter