Welcome Guest. Sign in or Signup

3 Answers

Speed steep spiral

Asked by: 6833 views , , , ,
Commercial Pilot

Does anybody have a rule of thumb for steep spirals speed. The Airplane Flying Handbook states: After the throttle is closed and GLIDING SPEED is established, a gliding spiral should be started and a turn of constant radius maintained around the selected spot on the ground. But for example if I use the glide speed on the cessna 150 (60 kts) in a 60 degree turn my stall speed will be 66. Since it‘s a 1-2 gs maneuver i don‘t want to end in a stall.

Regards.

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

3 Answers



  1. Dan S. on Sep 25, 2015

    Daniel,
    The load factor you are referring to (2g’s at 60 degrees bank) would only occur if you were maintaining level flight in a 60 degree bank. Since with this maneuver, you will be descending, the load that the aircraft is supporting will be much less than if you were to try a 60 degree bank in level flight. This is because the aircraft will not be having to overcome gravity as it would at level flight, and because you are descending you aren’t having to add the large amount of back pressure which would put you closer to the critical angle of attack. Go practice the maneuver, and if you will find that it will not be an issue!

    +6 Votes Thumb up 9 Votes Thumb down 3 Votes



  2. Daniel ENRIQUEZ EGUIGUREN on Sep 29, 2015

    Dan S.
    Please be careful! Your statements are WRONG, in fact if you are doing a 60 degree turn with power on you will have a much slower stall speed than with idle power, beacuse the wing load tend to be less with full power. You can experience load factors with and without power.

    -10 Votes Thumb up 1 Votes Thumb down 11 Votes



  3. Kris Kortokrax on Oct 14, 2015

    Daniel,

    It is interesting that you ask a question and when someone gives you an answer (the right answer, by the way), you tell him that he is wrong. If you knew the answer, why did you ask the question?

    There are several problems with your assumptions.

    1. You assume that when the Airplane Flying Handbook states to establish gliding speed, that it means to use the speed for maximum range. Where does it say that you cannot pick a higher glide speed?

    2. You ignore the fact that on page 4-29 of the Pilot’s Handbook of Aeronautical Knowledge, it discusses the load factors encountered in a “constant altitude turn” as Dan stated. In a descending turn, you are not maintaining the same back pressure as you would in a constant altitude turn. When I do a wingover, I reach a bank angle of 90 degrees at the halfway point. There is no attempt to maintain a constant altitude and the airplane experiences no more than 1 G while banked 90 degrees.

    3. The stall speed chart in the POH shows that at a 60 degree bank, the flaps up stall speed at the most aft CG is 65 KCAS (51 KIAS). At most forward CG, it is 68 KCAS (57 KIAS).

    4. The maximum glide speed is 60 KIAS, so the indicated stall speeds 51-57 are below 60. The speed for maximum glide is 1.05 – 1,17 times Vs1.

    5. In your post, you correctly described the spiral as a constant radius turn. That means that you do not establish and maintain a 60 degree bank. You vary your bank angle to maintain the constant radius, as in turns around a point or S turns. You would only approach the 60 degree bank when headed downwind. The bank shallows as you encounter more of a headwind. So the amount of time during which you would even approach the stall would be minimal.

    6. You should to be at a speed below maneuvering speed (Va) to perform the maneuver. That speed is shown as 93-104 KIAS.

    +10 Votes Thumb up 11 Votes Thumb down 1 Votes


Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.