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Introduction, V Speed Qs


JLang

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Hello all, I am a new owner of a 2007 CTSW, and (older) student pilot trying to finish PPL.  I bought the CTSW fairly early in my training when I decided it would be best to finish in the aircraft I would be flying/owning.  I only have my checkride left, which has proven difficult due to the lousy southwest Michigan weather.  So far I’ve had to postpone 5 times.  Anyway, I have a few Q’s for those of you wise in the ways of the wonderful CT.

 

The CTSW POH lacks a lot of information.  I’m curious what others are using for V speeds other than 0 deg flaps.

 

For Vx (15), I’ve been using 59kts.  This is the airspeed called out for a balked landing.

 

For Vy (15), I’ve been using 63kts.  The POH says to use 15deg flaps and 63kts for best glide speed, which should essentially be Vy.  But on this subject, I’m surprised that 15 deg flaps would result in best glide.  I note that the CTLS POH says to use 0 deg and 78kts for best glide, though I know that the CTLS is longer than the CTSW, with slightly different wingtips.

 

For Vy (-6), I’ve been using 84kts since, I dunno, it feels about right.

 

The aircraft is based at Hastings (9D9), which is just to the SE of GRR airspace.  Any CT owners in the area?  In cursory inquiries of local mechanics/avionics resources, it seems like this is a relative black hole; few have known what the CT is, let alone had any experience with one.

 

So far I’ve loved the plane, though the learning curve was (is) steep.  Very easy to fly.  Not easy to fly well.  I did a lot of research before choosing her, and she has not disappointed.  Before, I had about 20hrs training in a combo of Cherokee, Archer II, and C172, so I’ve loved the responsiveness and performance.  And after getting used to the twin D100/120 Dynons, I’d have trouble going back to steam gauges.  Don’t tell me how much nicer the big Skyviews are…

 

Finally, I have appreciated the great info I’ve gotten here so far.  I’ve already put to good use info in older posts about radiator tape, landing bulb replacement, spark plugs, etc.

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For Vx (15), I’ve been using 59kts.  This is the airspeed called out for a balked landing.

 

For Vy (15), I’ve been using 63kts.  The POH says to use 15deg flaps and 63kts for best glide speed, which should essentially be Vy.  But on this subject, I’m surprised that 15 deg flaps would result in best glide.  I note that the CTLS POH says to use 0 deg and 78kts for best glide, though I know that the CTLS is longer than the CTSW, with slightly different wingtips.

 

For Vy (-6), I’ve been using 84kts since, I dunno, it feels about right.

 

Finally, I have appreciated the great info I’ve gotten here so far.  I’ve already put to good use info in older posts about radiator tape, landing bulb replacement, spark plugs, etc.

 

Vy and Vx are takeoff angles/speeds (don't takeoff with zero or negative flaps).    The plane needs very little runway to takeoff so any obstacle clearance will rarely if ever need a Vx climb out even if high density altitude.  So, In general, takeoff at Vy with 15.

 

Best glide is an emergency procedure and you can get away with either 0 or 15 flaps probably in either plane...but the real answer is pull the chute if you are looking to crash land. 

 

Land at 55kts approach 15 flaps normal field, 52kts approach 30 flaps for short/soft fields.   The plane needs a just few hundred feet to land so there is rarely a need to adjust for short field unless you are landing on grass.

 

Once you are at a positive rate of climb you can go to negative flaps to climb faster and use negative flaps in all cruise phases.  You can also descend using negative flaps till you get near the airport.

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Your speeds look pretty good. I try to usually leave at best climb rate, which seems to be around 60kt at 15 flaps.

 

The best glide settings cause some confusion, and folks use a lot of different numbers. The POH says 63kt at 15 flaps, so I'd use that for your check ride. Testing has shown me that it actually glides better at -6 flaps and around 78kt. That makes sense since the best glide should be at least drag, which is the reflex setting. And I think the POH lists somewhere the best climb at -6 as 78kt, but I may get be mistaken on that. I wonder if Flight Design was hesitant to put such a fast glide speed in their POH for what is supposed to be a "slow" LSA, so they just used the slower 15 flaps numbers instead.

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Thanks for the replies!  I should explain that I understand that the difference between 59 and 63kts is probably insignificant in the real world, but my CFI, and I have heard my future examiner, expects me to run through these details in the pre-takeoff briefing.  "We will be performing a short-field takeoff.  15 deg flaps, full throttle, release brakes, rotate at 44kts, climb at Vx or 59kts until above the obstacle, nose down slightly to climb at Vy or 63kts until positive climb is established at about 150', flaps at 0 deg, climb at Vy or 78kts, ...."

 

The POH says Vx (0) is 66kts, Vy (0) is 78kts.

 

Interesting that you found -6 flaps to have best glide, and I agree that makes sense.

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Thanks for the replies!  I should explain that I understand that the difference between 59 and 63kts is probably insignificant in the real world, but my CFI, and I have heard my future examiner, expects me to run through these details in the pre-takeoff briefing.  "We will be performing a short-field takeoff.  15 deg flaps, full throttle, release brakes, rotate at 44kts, climb at Vx or 59kts until above the obstacle, nose down slightly to climb at Vy or 63kts until positive climb is established at about 150', flaps at 0 deg, climb at Vy or 78kts, ...."

 

The POH says Vx (0) is 66kts, Vy (0) is 78kts.

 

Interesting that you found -6 flaps to have best glide, and I agree that makes sense.

 

Yes. But you do get to have the POH in front of you if he wants exact Vx numbers.  The purpose is to make sure you have read the POH and know where to get the information. 

 

And negative flaps is not best glide because you are presumed to have an engine out.  Negative flaps leaves drag and loses lift in descent.  You will want to maintain some lift as you pitch for speed on the way down, but again...in this scenario teach yourself to be ready to use the chute.  No crash landing is  necessary in a plane with a parachute.

 

Most DPEs have never been in a plane like a CT.  They are not familiar with the chute and it's use so a proper answer to an emergency engine out is simply to say you will descend to an altitude of 500 ft agl looking for an open spot and pull the chute.  No need to try and reach a road or airport.

 

The Vx requirement is silly because the CT will takeoff and climb in Vy in far less runway, faster and steeper than any Cessna 172 (a common trainer).  You may ask the DPE if you can demonstrate a typical takeoff first before the short field so he can see how little runway you need and how quickly the CT jumps off the runway and try to avoid the Vx requirement.  I flew my CT in the Sierra mountains the entire time I owned the plane and never needed to do a Vx climb, even on runways at 5,900 feet MSL and density altitude of 8500 feet in the summer at KTRK (Truckee, Ca).

 

Ask your DPE for his weight and expected flight distance so you can make sure to get your W&B right and possibly fly with a little less fuel so the plane will stay quick and agile.  The DPE will be impressed that you thought to ask his weight and that you are calculating the W&B before the flight.   Also, it shows you are being both responsible and following AROW and making sure you have the correct VFR fuel reserves..

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Thanks for the replies!  I should explain that I understand that the difference between 59 and 63kts is probably insignificant in the real world, but my CFI, and I have heard my future examiner, expects me to run through these details in the pre-takeoff briefing.  "We will be performing a short-field takeoff.  15 deg flaps, full throttle, release brakes, rotate at 44kts, climb at Vx or 59kts until above the obstacle, nose down slightly to climb at Vy or 63kts until positive climb is established at about 150', flaps at 0 deg, climb at Vy or 78kts, ...."

 

The POH says Vx (0) is 66kts, Vy (0) is 78kts.

 

Interesting that you found -6 flaps to have best glide, and I agree that makes sense.

 

First off welcome to the forum, and good luck on your check ride. It sounds like your instructor has taught you well.

 

You are correct that the CTSW manual is lacking on speeds. The CTLS manual and flight training supplement does a better job providing numbers. You could use it to supplement where the CTSW manual is lacking.

 

Don't sweat the short field takeoff. I teach a normal take off with 15° flaps, so a short field is only different because of holding the brake and going full power before release. Soft field is the hard one to do well. With it you need to make sure you don't over rotate.

 

One thing that I teach different that how you said you will do it is I don't go to 0° flaps until 400 feet AGL. By doing that if you have an engine failure you are all set to land straight ahead.

 

One more thing on examiners. Most are good guys, and are expecting you to pass you check ride. You will have to do something dumb to not pass.  

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On your short field takeoff...you must have practiced it, correct?  The technique is to set flaps to 15, pull fully back on the stick, hold the brakes, throttle full, release the brakes and begin to push the stick forward and as you get light and start to leave the runway, stay level over the runway until you reach rotate speed, pull back on the stick and climb-out normally (Vx).

 

That is not the correct procedure for a short field takeoff. You are mixing soft field and short field together in a combination that will likely lead to a tail strike.

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That is not the correct procedure for a short field takeoff. You are mixing soft field and short field together in a combination that will likely lead to a tail strike.I

 

Yea, I didn't read his post carefully and combined soft and short field in some kind of brain fart.  I edited it.     I think he is getting a little too wound up over the speeds IMHO.  I have landed the CT much faster than book..and never had an issue.  And never took off in a Vx climb even in the mountains.   And was often asked to make a mid-field exit over terminal buildings and radar towers at ATC request given how fast the plane climbs and how slowly it flys to end of a long runway (KRNO). 

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Before you take anybody's word for speeds or procedures, you might want to be sure that the author has experience in the specific airplane - CTsw - that you are flying.  Also, some here are instructors and some aren't (I am not).  

 

I have about 800 hours in my 2006 CTsw.  I am comfortable with your speeds.  I generally do not climb Vy with 15 degrees of flaps.  If I want a Vy climb, I use 0 degree flaps (in part because of the omission of a published Vy with 15 degrees of flaps).  On a related issue - after your check ride, you may want to compare your take-off engine speeds at each of the V-airspeeds to guidelines published in recent Rotax documentation.  In our airplanes, it is easy to get the engine below recommended full-throttle RPM on take-off, especially with 15 degrees of flaps.  This has been discussed elsewhere on this forum.

 

I trained in my CTsw and took my check ride in it.  I was concerned about the difference in performance and handling (in all phases of flight) that I was likely to experience between flying with the right seat empty (during my solo training) and flying with the right seat occupied (with the examiner).  So, for much of my solo training, I carried 175 pounds of ballast on the passenger seat so that I would experience little difference with the examiner in the airplane.  If you decide to carry ballast, be sure it is well secured and at no risk of fouling the flight controls at any time (e.g., turbulence).

 

Good luck!

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Got a little over 600 hours in my 2006 CTSW and am an instructor and have taught in mine and in a 2005 (built late in the year so it had the 2006 changes).  I use 60 knots for a takeoff/climbout with 15 flaps, and use 66 knots as Vx and 78 as Vy with 0 flaps and 84 as Vy with -6.  Frankly, if I were doing a short field takeoff with an immediate climb over obstacles, I'd climb at 60  knots at 15 flaps and then clean up and transition to a 67 knot Vx climb once well clear and if still needed.

 

I use 300 feet AGL as my flap transition altitude for a flaps 15 takeoff.

 

Like folks have said, the POH is a bit confusing about best glide and the flap setting.  I haven't done any hard experimenting (i.e. taking data) but I have done enough to convince me best glide is not at 63 knots and 15 flaps.  It glides pretty well at 63 knots at 0 flaps, but mine seems to do best at about 65 knots with 0 flaps.  Mr. Walker has me curious about  -6 and 78; have to play with that and see!  (One poster mentioned that best rate of climb and best glide are usually the same airspeeds, and that is correct.  Might have something else to go play with!)

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And negative flaps is not best glide because you are presumed to have an engine out.  Negative flaps reduces drag and lift (level cruise maintained with the engine).  You will want to maintain some lift as you pitch for speed on the way down

 

Well, yes.  But -6° doesn't kill all the lift.  My testing seems to show that the decrease in lift is outweighed by the decrease in drag.  I can glide noticeably farther at 78 and -6° than I can at 70 at 0° or 63 at 15°.  Testing is the only way to resolve this for oneself.  Basic aerodynamics suggests that the best glide will *not* be the POH value of 63 at 15°, that is just too draggy a configuration to get best glide distance.  But again, test and see, but use the book values until after your check ride.  

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Frankly, if I were doing a short field takeoff with an immediate climb over obstacles, I'd climb at 60  knots at 15 flaps and then clean up and transition to a 67 knot Vx climb once well clear and if still needed.

 

I use 300 feet AGL as my flap transition altitude for a flaps 15 takeoff.

 

 

That's close to how I do every takeoff.  15° at 60kt until 400ft AGL, then go to 0°, followed quickly by -6° once the speed is over 70kt.  I usually climb at 90kt, unless I'm really trying to gain altitude quickly, in which case I'll pitch for 78-80kt.  That does get the temps to come up quickly in the summer so you have to keep an eye on it. 

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Hello all, I am a new owner of a 2007 CTSW, and (older) student pilot trying to finish PPL.  I bought the CTSW fairly early in my training when I decided it would be best to finish in the aircraft I would be flying/owning.  I only have my checkride left, which has proven difficult due to the lousy southwest Michigan weather.  So far I’ve had to postpone 5 times.  Anyway, I have a few Q’s for those of you wise in the ways of the wonderful CT.

 

The CTSW POH lacks a lot of information.  I’m curious what others are using for V speeds other than 0 deg flaps.

 

For Vx (15), I’ve been using 59kts.  This is the airspeed called out for a balked landing.

 

For Vy (15), I’ve been using 63kts.  The POH says to use 15deg flaps and 63kts for best glide speed, which should essentially be Vy.  But on this subject, I’m surprised that 15 deg flaps would result in best glide.  I note that the CTLS POH says to use 0 deg and 78kts for best glide, though I know that the CTLS is longer than the CTSW, with slightly different wingtips.

 

For Vy (-6), I’ve been using 84kts since, I dunno, it feels about right.

 

The aircraft is based at Hastings (9D9), which is just to the SE of GRR airspace.  Any CT owners in the area?  In cursory inquiries of local mechanics/avionics resources, it seems like this is a relative black hole; few have known what the CT is, let alone had any experience with one.

 

So far I’ve loved the plane, though the learning curve was (is) steep.  Very easy to fly.  Not easy to fly well.  I did a lot of research before choosing her, and she has not disappointed.  Before, I had about 20hrs training in a combo of Cherokee, Archer II, and C172, so I’ve loved the responsiveness and performance.  And after getting used to the twin D100/120 Dynons, I’d have trouble going back to steam gauges.  Don’t tell me how much nicer the big Skyviews are…

 

Finally, I have appreciated the great info I’ve gotten here so far.  I’ve already put to good use info in older posts about radiator tape, landing bulb replacement, spark plugs, etc.

 

If you PM me your email address I can send you a copy of our standard operating procedures we use for our flight school.  Its geared for our CTLS, but much of the info will apply to your CTSW.  We owned a CTSW first and put about 600hrs instructing in it, now have a CTLS we have 2000hrs teaching in.

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Well, yes.  But -6° doesn't kill all the lift.  My testing seems to show that the decrease in lift is outweighed by the decrease in drag.  I can glide noticeably farther at 78 and -6° than I can at 70 at 0° or 63 at 15°.  Testing is the only way to resolve this for oneself.  Basic aerodynamics suggests that the best glide will *not* be the POH value of 63 at 15°, that is just too draggy a configuration to get best glide distance.  But again, test and see, but use the book values until after your check ride.  

 

Neg flaps produce more negative air pressure on top of the wing producing a small amount of added lift and reduced drag but only if in level cruise.  This is why they provided the negative flap settings as a way to gain fuel efficiency in level flight.

 

When gliding you want  0 flaps and pitch for speed for the longest distance.

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Neg flaps produce more negative air pressure on top of the wing producing a small amount of added lift and reducing drag but only if in level cruise.  When descending you change the angle of attack and negate the effect of the lift but leaving only drag.   This is why they provided the negative flap settings as a way to gain fuel efficiency in level flight.

 

When gliding you want either 0 flaps for higher speed descents or 15 for slower descents (not exceeding the airspeed for that flap setting) to get the most distance on the way down.

 

I don't think you are correctly stating how AoA works.  It has nothing to do with whether you are descending, climbing, or level.  That's why it's called *relative* wind.  

 

What you are saying might be true if we were talking about gliding at 0° and -6° at the same speed, but we're not.  We are compensating for the decreased lift by selecting a higher glide speed, keeping AoA approximately the same as the effective chord line changes with wing geometry. 

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I don't think you are correctly stating how AoA works.  It has nothing to do with whether you are descending, climbing, or level.  That's why it's called *relative* wind.

 

Pitching the nose up increases angle of attack or pitching down decreases angle of attack.

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So that's 2 votes for 400 and one for 300 to switch to 0 flaps after take off.

 

I use 400ft, but I don't think it matters much as long as you have sufficient height and airspeed such that the airplane is not going to settle back to the runway (or into the trees/buildings/towers at the end of the runway) when you make the configuration change.  If you climb out at a higher speed, or lower the nose a little to pick up speed before retracting the flaps, the "settling" effect will be much less.  

 

When trying to get somewhere fast or catch up with another airplane, I have climbed at 68kt @ 15° (instead of my normal ~60kt) and retracted the flaps at 100ft or so over the runway.  There is no real change in climb profile at that speed when you retract.  There are lots of safe ways to do it, depending on what you are trying to do and what the conditions are.  

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Neg flaps produce more negative air pressure on top of the wing producing a small amount of added lift and reduced drag but only if in level cruise.  This is why they provided the negative flap settings as a way to gain fuel efficiency in level flight.

 

When gliding you want  0 flaps and pitch for speed for the longest distance.

 

Your reply reminds me of an old proverb that goes something like this. It is better to be quiet and be thought a fool, rather than opening your mouth and proving yourself a fool.

 

The reason for the negative flaps as relayed to me by a Flight Design engineer is to reduce loading on the trailing edge of the wing due to the shape of the airfoil. A benefit of this is reduced drag. As for lift being created and increased negative pressure because of the negative flap position, you are wrong. By going to negative flaps you are essentially moving the cord line of the wing reducing the curvature of the upper surface. This reduced curvature means that the airfoil will not be producing as much low pressure above the wing as compared to 0° flaps. The reduction of low pressure produced leads to less lift not more. To compensate for the reduced low pressure and decreased lift you must increase airspeed to regain the lift lost.

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I use 400ft, but I don't think it matters much as long as you have sufficient height and airspeed such that the airplane is not going to settle back to the runway (or into the trees/buildings/towers at the end of the runway) when you make the configuration change.  If you climb out at a higher speed, or lower the nose a little to pick up speed before retracting the flaps, the "settling" effect will be much less.  

 

When trying to get somewhere fast or catch up with another airplane, I have climbed at 68kt @ 15° (instead of my normal ~60kt) and retracted the flaps at 100ft or so over the runway.  There is no real change in climb profile at that speed when you retract.  There are lots of safe ways to do it, depending on what you are trying to do and what the conditions are.  

 

Andy, I teach 400 feet for the reason stated in my earlier post.

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Pitching the nose up increases angle of attack or pitching down decreases angle of attack.

 

Really, that's all there is to it?  What if you pitch up and increase speed?  What if you pitch down and go into a 3g turn at the same time?  

 

Again, RELATIVE wind.  Time to re-read "Stick and Rudder".

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Neg flaps produce more negative air pressure on top of the wing producing a small amount of added lift and reduced drag but only if in level cruise.  This is why they provided the negative flap settings as a way to gain fuel efficiency in level flight.

When gliding you want  0 flaps and pitch for speed for the longest distance.

 

Your reply reminds me of an old proverb that goes something like this. It is better to be quiet and be thought a fool, rather than opening your mouth and proving yourself a fool.

You put that in the kindest way possible, but squarily hit the nail on the head.

 

 

The reason for the negative flaps as relayed to me by a Flight Design engineer is to reduce loading on the trailing edge of the wing due to the shape of the airfoil. A benefit of this is reduced drag. As for lift being created and increased negative pressure because of the negative flap position, you are wrong. By going to negative flaps you are essentially moving the cord line of the wing reducing the curvature of the upper surface. This reduced curvature means that the airfoil will not be producing as much low pressure above the wing as compared to 0° flaps. The reduction of low pressure produced leads to less lift not more. To compensate for the reduced low pressure and decreased lift you must increase airspeed to regain the lift lost.

Thank you for posting factual information from a credible source. It makes perfect sense.

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Pitching the nose up increases angle of attack or pitching down decreases angle of attack.

The direction of the nose, even the direction of the entire plane has nothing to do with AoA! Flying 101 Angle of Attack is determined by relative wind in relation to the chord of the wing. Stall angle can be exceeded in any attitude - vertical, horizontal, ascending, descending, inverted - any attitude!

Ther have been tons of great articles on this, there are tons of excellent books. It has been a safety topic at FAAST seminars. I don't get how you missed it.

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