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  #11  
Old 02-07-2012, 07:50 PM
Mtbguy Mtbguy is offline
 
Join Date: May 2011
Location: Atlanta GA
Posts: 22
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Quote:
Originally Posted by Jetlinkin View Post
I recently attended APS emergency maneuver training in Phoenix, Az. This was probably the best aviation training that I have ever received!

For all of us, experiencing these many different types of upsets could possibly save our lives. I can't say enough how invaluable this training was.

This is only the tip of the iceberg during my experience, if you have any questions let me know. Here is the highlight reel from the last 40 minutes of my training.
http://www.youtube.com/watch?v=1fM9_...g6NomixB_54kJX
Thanks for sharing this. I have been a part 121 airline guy for 15 years and only in recent years has there been more emphasis on this.
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  #12  
Old 02-08-2012, 07:04 AM
Vac Vac is offline
 
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Location: Niceville, Florida
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Hi Steve,

Sorry about the lingo, let me see if I can give a better answer than "it depends..."

"A proper unload" - What exactly does the pilot do to perform this?

-Ailerons and rudder neutral, do what it takes with fore/aft stick to make the G-meter read "1/4." If you're mostly right side up, that likely means forward pressure on the stick, if you're mostly upside down, you've got radial G working for you, so that means less forward pressure. The key is to make the meter read "1/4" (or zero, or whatever your target is). Since looking at a G-meter isn't always practical, each of us develops seat-of-the-pants cues to help...if everything is floating up in the cockpit around you and the engine is sputtering, you're probably close to a zero G condition.

"Any nose rise/slice/stick force lightening or buffet, neutralize control inputs and unload to a 1/4 G condition" - I am not sure what you mean by "slice" and again what specific action is the pilot performing to "unload to a 1/4 G condition"?

-These are subtle cues that the airplane gives before it stalls. I'm not familiar with the handling characteristics of the airfoil on your -9, but the 23013.5 section on the 3/4/6/7/8 as a rather abrupt break at the stall (i.e., there is zero.zero doubt when the wing quits flying!). Prior to that point you can experience buffet, nose rise or slice.

Nose rise is tough to perceive unless you're looking for it. It occurs when you're maneuvering and pulling aft on the stick and the nose continues to rise even though you've unloaded a bit to try to stop it. It occurs because the CG is rotating over the top or underneath the aerodynamic center and your pitch stability is decreasing (it's like your elevator suddenly got bigger/more effective). It feels as though the stick just got lighter in your hand.

Nose slice is simply when the nose starts to slide to the left or the right. Again, I'm not familiar with the -9, but when you put our -4 (loaded within aerobatic design limits as specified by Van) into a deep stall, i.e., maintain full aft stick, the nose will slide before the airplane drops off in a spin. In a -4, there is sufficient rudder to counter this slice. The same cue can occur just prior to the stall as well, it's just telling you that your directional control is starting to break down (think of your tail being blanketed or less effective).

Because of the torque effects of the prop, sometimes this slicing gets mixed with some roll as the airplane decelerates. You can experience this when you do a power-on stall. If you do the classic 1 knot/sec decelleration as you approach the stall, the airplane will start to roll to the left a bit, and chances are if you're not looking for it, you may add some right aileron to help out your decreasingly less effective tail, but then when the airplane stalls, the left wing drops suddenly. If, however, you only use your feet to counter roll/slice to the left and quit trying to stop it as you run out of authority, the airplane will stall straight ahead (no wing drop).

"wait until the velocity vector transits the horizon and airspeed increases" - What is "velocity vector"? What is the pilot observing in this state?

-Velocity vector = flight path or where the airplane is going (but not necessarily where its pointing). If the airplane is going in a direction above the horizon, it will slow down. If the airplane is going in a direction below the horizon, it will speed up. This is gravity's contribution to "thrust."

If you unload before a stall (or loss of directional stability), the flight path of the airplane is just a ballistic trajectory (like throwing a ball). If you've got sufficient altitude, eventually the path with get below the horizon and the airplane will start to speed up. After you've got sufficient airspeed, you can recover from any unusual attitude you might be in. 100 is just a nice round number and you've got about 3.3 G's available for maneuvering--likely fast enough to help avoid a secondary stall if you're too quick with back pressure when you try to recover. The real thing to be careful of in any RV is once the nose is down getting too fast, as I'm sure you've experienced.

Hope that helps a bit. Feel free to drop a line if you have any more questions.

Cheers,

Vac
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RV-4 2112
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Last edited by Vac : 02-08-2012 at 07:11 AM.
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  #13  
Old 02-08-2012, 07:53 AM
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N355DW N355DW is offline
 
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Location: Port St Lucie, FL
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Default These courses are so important

Quote:
Originally Posted by Mtbguy View Post
An aircraft in normal steady state (cruise flight) is under the force of 1g. Remember when your CFI showed you pencils floating in the cockpit to you once? ( I am almost positive they did- most show you that). When the pencils float it is essentially a zero g or negative G maneuver depending on how hard/quick they move controls. Its not just pushing the nose down at 1 G to break out of the stall, its on the verge of an aerobatic maneuver. If done properly you can fly an average piston airplane almost straight up (for a few short moments) without stalling it. It is the same as shooting a bullet straight up into the air or throwing a stone, at the top of the arc it slows down to zero for a moment before starting to fall downward at velocity again.
Good points. Let me add my 2c!

You can fly an aircraft straight up until you stop, kick the rudder to turn and fly straight down toward the ground and pull out, and never come anywhere close to stalling the aircraft. You can also fly the aircraft straight up, let it get on it's back slightly, stall inverted, kick the rudder and go into an inverted spin. You can easily stall the aircraft when it's going straight at the ground. (This all being done in an aircraft that is strong enough to withstand backward airflow, and higher g-loads of course.) Stall speed has nothing at all to do with the aircraft's attitude in relation to the ground, and everything to do with the angle of attack. With enough experience you can feel when the wings have an angle of attack, either positively or negatively loaded. You can also feel when the wings have no angle of attack, just as you can feel yaw from the rudder.

For example, a common mistake many pilots make when doing a hammerhead is to not unload the wing when in the vertical. When you pull from straight and level to vertical during the first part of the hammerhead, the aircraft often still has a slight positive angle of attack, because even though the attitude is vertical, there is still a slight horizontal component from the aircraft's momentum. You can get a zero angle of attack by "popping" the stick forward slightly after reaching the vertical. If done properly, you will feel yourself float out of your seat as the aircraft goes straight up. If you don't do this, the wing is still flying, and that can make the aircraft want to roll even more than usual in the turn at the top, more than the aileron can prevent. Another common mistake for new acro pilots is to let the aircraft get on it's back ever so slightly as it's in the vertical. If you do this, and then misjudge the time to kick, if the aircraft starts to fall backward you will now have a negative angle of attack on the wings which can stall even at a very slight angle (because your airspeed is so low). If you kick the rudder as this happens, you can get into a nice inverted spin pretty quickly. Even if you kick early and fly it over the top, if you have let the aircraft get slightly on it's back, it can still have a negative angle of attack and go into an inverted spin.

Once you have some experience with this, it's easy to tell when it's going to happen. You can feel the aircraft's angle of attack, and if you keep it at zero, then even at zero airspeed you will not stall. But if you develop even a slight angle of attack at a very low airspeed, and impose any sort of g load, it's very easy to stall.

I know that most people will probably disagree with me, but in my not so humble opinion , courses like these should be required for anyone who wants to fly with trusting non-pilot passengers.
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Last edited by N355DW : 02-08-2012 at 08:04 AM.
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  #14  
Old 02-08-2012, 09:28 AM
gereed75 gereed75 is offline
 
Join Date: Sep 2007
Location: pittsburgh pa
Posts: 533
Default Here's a reference

For those wishing to know a lot more about this stuff, here is a good reference

https://www.cnatra.navy.mil/pubs/folder5/T34C/P-354.pdf

This is the out of control flight instruction manual for Navy basic training in the T-34C. The T-34 has performance/flight characteristics similar enough to RV's to be usefully comparable.

By the way, I highly recommend other CNATRA (Navy Training) publications. The basic Flight Training instruction - https://www.cnatra.navy.mil/pubs/fol.../P-330_CH9.pdf is excellent, particularly in regards to the emergency engine out procedures. This lays out the High Key - Low key pattern that is oft discussed here on the forum. Also describes really good landing pattern procedures from downwind to landing - including correct waveoffs and the whole nine yards.

All of these documents can be found here https://www.cnatra.navy.mil/pubs/ppub_t34_pri.htm

Your tax dollars at work!!! might as well get some valuable info for your money. Might save your bacon and will definately make you a better pilot.
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Last edited by gereed75 : 02-08-2012 at 09:46 AM.
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  #15  
Old 02-08-2012, 09:57 AM
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RVbySDI RVbySDI is offline
 
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Location: Tuttle, Oklahoma
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Mike,
Thank you for the clarifications. Since I am not into aerobatics (hey I fly a non-aerobatic 9) I am not really looking to go experience this in my plane but I am interested in understanding these concepts. The truth is I am not really interested in intentionally doing these maneuvers for the pleasure of aerobatic flying like many RV fliers out there. However, I would like to be experienced in the theory and would like to have an opportunity to practice them for the purpose of emergency recovery.

By the way, you commented that you were not familiar with the characteristics of the 9 in stall. The 9 also has a distinct abrupt break at the stall. In addition, I have not heard other 9 pilots comment before about this but, with my particular 9, there is a very distinct "stick shacking" prior to the stall. This is a very unmistakable sudden and distinct shaking that occurs to the stick just prior to the break. There is absolutely no way a pilot could miss this shaking prior to the stall. Now with the 9 being non-aerobatic I have not tested nor experienced this in any inverted attitude but in every other "normal" attitude I have had my plane in it is there. Power on and power off both produce this shaking. Because of this I am very confident I have ample warning of impending stalls.

Again, thank you for the information. I love this forum for this specific reason. I love the fact that I have access to people with this kind of experience that I can learn from.
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  #16  
Old 02-08-2012, 06:13 PM
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Snowflake Snowflake is offline
 
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Quote:
Originally Posted by PCHunt View Post
Decreases is correct. OTOH, if you increase the G loading up to 2 G's, the stall speed increases. The higher the G, the higher the stall speed, and vice-versa. At zero G, you can't stall the plane.
Right... I think I was confusing the *margin* between airspeed and stall speed, with the stall speed itself.
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  #17  
Old 02-08-2012, 07:33 PM
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bach33089 bach33089 is offline
 
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Location: Ocala, FL (Leeward Air Ranch)
Posts: 30
Default Sorry... aerobatics nut here!

I'll start by saying I'm an aerobatics nut, and have spent quite a bit of time not flying straight and level. I see one thing repeated over and over again here that is causing confusion and is increasingly important in "all attitude flying" that this idea be understood! Everything I have seen so far says "Stall Speed." Airplanes don't stall because of speed (I know you all know this), it stalls at an AOA. I can stall my Extra at 200 knots (ouch...), I can also fly (not stall) it at 0 airspeed.

When we bore holes in the sky maintaining one G flight, straight and level, the speed that CORRELATES to the critical angle of attack is relevant. However, as soon as you start pulling Gs (think a steep turn from base to final) SPEED BECOMES IRRELEVANT, you cannot know your precise stall speed at a given flight load and weight unless you moonlight as a calculator/genius/nuclear physicist... (point taken?) This is why it becomes important to maintain a safe margin above the published stall speed (1.3 times Vso commonly) when maneuvering low and slow. Where this takes another turn (and when you REALLY start flying) is when you begin to maneuver for something other than landing, i.e. AEROBATICS. Most everything in aerobatics is done by sight, sound, and feel. It takes A LOT of time and experience to start to feel the stall coming, but once you begin to know all of the indicators (previously explained as Buffet, Nose Rise, and Slice, but also can include sounds like the distinctive whistle the Extra makes before it stalls, or when it is ready for you to kick at the top of a Hammerhead) that "specific stall speed" means less and less. I know this seems like rambling, but here is my point. As you explore the flight envelope of your airplane (as it relates to stalling tendencies) you will be able to KNOW when the airplane is close to the stall. Rather than having to do rapid integration in your head to CALCULATE a stall speed at .25G going 150 knots at 1700 pounds, you KNOW that buffet means trouble is brewing. Not to mention this "research" is insanely fun (and addictive)! Just make sure you get good and appropriate training, and explore away! I think EVERYONE should go through a similar training experience, it is very unique to fly and airplane in which you can go and DO everything you talk about in ground school. It brings practical instruction to a whole new level! Fly Safe guys, keep the blue side down as much as you can!
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  #18  
Old 02-08-2012, 08:28 PM
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frankh frankh is offline
 
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Location: Corvallis Oregon
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also a fan of acro.

I spent a while trying to get my 7a (with CS prop on a 2.25" prop extension) to spin inverted...No chance!

Then one day I was doing the hammerhead fell off the back at the top and bang, the thing snapped over into a very impressive invert spin.

I rode it down a little just for kcks and it wound up pretty quickly (for a spinning RV).

I guess this is why self taught aerobatics is a bad idea eh?...

Frank
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  #19  
Old 02-09-2012, 04:49 AM
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N355DW N355DW is offline
 
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Location: Port St Lucie, FL
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Quote:
Originally Posted by frankh View Post
also a fan of acro.

I spent a while trying to get my 7a (with CS prop on a 2.25" prop extension) to spin inverted...No chance!

Then one day I was doing the hammerhead fell off the back at the top and bang, the thing snapped over into a very impressive invert spin.

I rode it down a little just for kcks and it wound up pretty quickly (for a spinning RV).

I guess this is why self taught aerobatics is a bad idea eh?...

Frank
Yes indeed. When I ride with students who do this, I can always tell when this is going to happen. They are almost always surprised when it does.

For those of you who are frightened by the very thought of unusual attitudes, I will say this:

When I was first getting my CFI back in the early eighties, I thought it might be nice to take an aerobatic course in case a student "did something crazy."

I signed up for a ten hour course with Duane Cole. For the first two hours I was terrified, everything was a blur.

After five hours I was more relaxed, and at the end of the course I was loving it so much I went home and bought a Citabria! (Paid $7500 for it, those were the days!)

My point is, if you can get past the initial nervousness and fear, the rewards of learning aerobatics are numerous. You will have a much better feel for your aircraft, your confidence level will go up quite a bit, and you will simply be a much better "stick".

Plus, as others have said, it's a lot of fun, and if you become interested in competition, the IAC is filled with really cool people!

If you just aren't up to the G's, and some folks aren't, even after trying for a while, even an unusual attitude course as the OP talks about can be invaluable, building both skill and confidence, and feel for your aircraft.
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  #20  
Old 02-09-2012, 08:29 AM
David Paule David Paule is offline
 
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Location: Boulder, CO
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Default Small Thing

Quote:
Originally Posted by Jetlinkin View Post
....One interesting tidbit I learned from this training, if you unload your aircraft from 1G to 1/2G, your stall speed decreases by 42% ( it's a good thing to know when you are in a stall).....
The decrease is "only" 29%, not 42%. Still significant but you might want to go back and check other arithmetic factoids they taught.

(The decrease itself is 29% of the original speed. It's 41% of the lower speed, and that's how they made their error. The extra 1% is a goof.)

Dave
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