is there such thing as Improved Vr for lighties.
is there such thing as Improved Vr for lighties.
Did a nav today in an Arrow down to EN. 38 deg. A careful study of the P charts showed we were good to go even at 100kg below MTOW.
Holy cow, was the take-off roll long. Rwy 35 and after a slowacceleration and rotate, lifted off at the last touchdown zone marker at the other end, a bit past the tower. Google earthing it seems to indicate almost 1100m for the ground roll. Now i'd uped the Vr number by 10 kts to get as close to Vy.
Is there any benefit to this for the climbout in really hot weather?
Holy cow, was the take-off roll long. Rwy 35 and after a slowacceleration and rotate, lifted off at the last touchdown zone marker at the other end, a bit past the tower. Google earthing it seems to indicate almost 1100m for the ground roll. Now i'd uped the Vr number by 10 kts to get as close to Vy.
Is there any benefit to this for the climbout in really hot weather?
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Be careful when pulling he nose wheel off early as you will increase the angle of attack to some extent and potentially drastically reduce acceleration during the ground roll. I doubt that the POH would recommend that approach and if you are close to the edge on performance I would not recommend it.
Remember, aircraft performance charts are based on a new aircraft, recently weighed. You may have been flying an old aircraft, not recently weighed and down on compression and as such underpowered.
To answer the question... Refer to the POH.
Practically though, a few extra knots does give a "clean break" from the runway (particularly in a crosswind) and more airspeed to play with which you could use to your advantage for additional altitude.
Remember, aircraft performance charts are based on a new aircraft, recently weighed. You may have been flying an old aircraft, not recently weighed and down on compression and as such underpowered.
To answer the question... Refer to the POH.
Practically though, a few extra knots does give a "clean break" from the runway (particularly in a crosswind) and more airspeed to play with which you could use to your advantage for additional altitude.
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Vr+10 is a bit too fast, particularly when you are trying to achieve a P-chart distance. OK, EN is pretty long and the Arrow is only a little aeroplane but, the mindset of 'tacking on a bit for Mum and the kids' can lead to embarassment one day down the track when you don't have 1500 odd metres to play with.
As previously mentioned. What does Mr. Piper say when it comes to flying his product?
"A careful study of the P charts showed we were good to go even at 100kg below MTOW." Are you sure?? Don't forget you are climb weight limited on such hot days! Ahhh..I miss the old Australian manual P-charts!
Density Altitude and its effects on aircraft performance seem to be forgeotten a bit by you low landlubbers by the sea as well. I reckon the density alt would have been about 3100ish today.
Please don't take this as a 'let's form a posse and lynch to nearest 300hour grade 3 instructor who didn't teach me the hot'n'high take off technique' post. I'm sure that would create more thread drift than a (said 300hour grade 3 instructor) P-plater in a Nissan Skyline.
Cheers for now,
In-cog
As previously mentioned. What does Mr. Piper say when it comes to flying his product?
"A careful study of the P charts showed we were good to go even at 100kg below MTOW." Are you sure?? Don't forget you are climb weight limited on such hot days! Ahhh..I miss the old Australian manual P-charts!
Density Altitude and its effects on aircraft performance seem to be forgeotten a bit by you low landlubbers by the sea as well. I reckon the density alt would have been about 3100ish today.
Please don't take this as a 'let's form a posse and lynch to nearest 300hour grade 3 instructor who didn't teach me the hot'n'high take off technique' post. I'm sure that would create more thread drift than a (said 300hour grade 3 instructor) P-plater in a Nissan Skyline.
Cheers for now,
In-cog
Google earthing it seems to indicate almost 1100m for the ground roll. Now i'd uped the Vr number by 10 kts to get as close to Vy.
Increasing your lift off speed by 10 kts is exceeding the correct speed by over 13%, which will dramatically increase your ground roll beyond that considering you are trying to accelerate with ground friction and the gear still extended. Rotating too early does increase take-off distance as well.
The Piper P-Charts for most pipers end at 38C (100F) at sea level, by 2000ft then limit temp is down to 33C. Essendon being at 300ft would put the limit temp around 37C.
Why do i refer to a limit temperature on the Piper charts? Piper has stated in a number of earlier accidents that where the temp lines end marks the environmental limit and performance will degrade substancially from this point and can not be determined safely. If the aircraft is operated beyond these lines it is outside of certified limits. This is also the reason in performance theory you are told that you can interpolate between the lines, but never extrapolate or extend the lines.
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Vr for props? No such thing
From a 35,000 hour pilot called John Deakin (pelican perch):
There is also NO SUCH THING as "Vr" or "Rotation" in a prop airplane! That is strictly a jet certification term, and has several very specific meanings that do NOT apply to props! I always get a chuckle out of the idea of "rotating" any prop airplane, especially something like a Cherokee.
Of course, do what the POH says - TOSS around all day. I've watched an XL-750 (not flown by an ag pilot) do every take off with the mains in the air, nose wheel still running along the ground because the pilot would only 'rotate' at the 'TOSS'. Oh please.
There is also NO SUCH THING as "Vr" or "Rotation" in a prop airplane! That is strictly a jet certification term, and has several very specific meanings that do NOT apply to props! I always get a chuckle out of the idea of "rotating" any prop airplane, especially something like a Cherokee.
Of course, do what the POH says - TOSS around all day. I've watched an XL-750 (not flown by an ag pilot) do every take off with the mains in the air, nose wheel still running along the ground because the pilot would only 'rotate' at the 'TOSS'. Oh please.
Last edited by Lumps; 25th Jan 2012 at 11:13.
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...the aircraft will let you know. Fly with some FEEL lads!
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Good point os, great extension lumps' post. 
Feel what the aeroplane is doing. I.e The arrow IV will begin to attempt to bounce the nose wheel approaching 60 knots (arrow 3's do it also, but not so pronounced). A little back pressure cures it. great op to do a rescan of your eng instruments and asi. by the time you get through that she's pretty much ready to fly.
Adding 10 knots? hmm IIRC the old CASA chart for something like the 210 also has a TOSS line. If you can find one, do one with any given set of numbers, and then add 10 knots to the TOSS and work backwards a bit. You will be surprised at the effect.
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Don't get me started on the old Casa charts
A few have had a crack at me because I liked them. Most of the Yankee manufacturers charts rely on you using 'rules of thumb' for things like different surfaces.
So wheres this list of 'rules of thumb' we are now supposed to use
Worst change i have seen! (other than juliar)
Feel what the aeroplane is doing. I.e The arrow IV will begin to attempt to bounce the nose wheel approaching 60 knots (arrow 3's do it also, but not so pronounced). A little back pressure cures it. great op to do a rescan of your eng instruments and asi. by the time you get through that she's pretty much ready to fly.
Adding 10 knots? hmm IIRC the old CASA chart for something like the 210 also has a TOSS line. If you can find one, do one with any given set of numbers, and then add 10 knots to the TOSS and work backwards a bit. You will be surprised at the effect.
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Don't get me started on the old Casa charts
A few have had a crack at me because I liked them. Most of the Yankee manufacturers charts rely on you using 'rules of thumb' for things like different surfaces.So wheres this list of 'rules of thumb' we are now supposed to use
Worst change i have seen! (other than juliar)
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Old CASA charts.
Who were the Trendsetters that started this poor technique! Students would pick this up from other students. I lost count of the number times I had to explain AGAIN the meaning of TOSS and that it's not a rotate speed.
There are some instructors at Moorabbbin that teach their students to hold Seminoles on ground until blue line before rotating!
Why? They believe its safer in case of EFATO. I reckon at 88kts, the only thing still on the runway will be the nose wheel. I wonder if this was a contributor to a number of
Totally agree with previous posts regarding feel and tailwheel time.
As I have said in the past. "There are two types of students. Those who want a Pilot's licence, and those who want to learn to fly!"
In-cog
nose wheel still running along the ground because the pilot would only 'rotate' at the 'TOSS'. Oh please.
There are some instructors at Moorabbbin that teach their students to hold Seminoles on ground until blue line before rotating!
Why? They believe its safer in case of EFATO. I reckon at 88kts, the only thing still on the runway will be the nose wheel. I wonder if this was a contributor to a number of Totally agree with previous posts regarding feel and tailwheel time.
As I have said in the past. "There are two types of students. Those who want a Pilot's licence, and those who want to learn to fly!"
In-cog
So wheres this list of 'rules of thumb' we are now supposed to use
It is just a draft but has what CASA thinks is safe allowances on page 20-21.
What exactly is a TOSS when talking about singles. Never ever heard it applied to a single before.
As for Vr (a term that's not usually used for a lighty) I'm guessing we are talking about raising the nose wheel, why would you increase this speed ever (unless you're over gross)? The aircraft's performance is based around IAS, so while TAS (ground speed in this case) may by greater with higher DA's there's no need at all to be playing around with the speed at which you raise the nose.
For a given weight the aircraft's stall speed remains the same no matter what density altitude therefore your minimum 50 foot speeds are also always the same. The best rate of climb speeds will change due to changes in power output (assuming normally aspirated), however the change will generally be small, about 1 knot decrease per 1000' DA increase.
I have to ask the original poster why he/she thought it a good idea to increase the lift off speed? If your instructor suggested it then he/she needs some remedial P of F.
As for Vr (a term that's not usually used for a lighty) I'm guessing we are talking about raising the nose wheel, why would you increase this speed ever (unless you're over gross)? The aircraft's performance is based around IAS, so while TAS (ground speed in this case) may by greater with higher DA's there's no need at all to be playing around with the speed at which you raise the nose.
For a given weight the aircraft's stall speed remains the same no matter what density altitude therefore your minimum 50 foot speeds are also always the same. The best rate of climb speeds will change due to changes in power output (assuming normally aspirated), however the change will generally be small, about 1 knot decrease per 1000' DA increase.
I have to ask the original poster why he/she thought it a good idea to increase the lift off speed? If your instructor suggested it then he/she needs some remedial P of F.
Last edited by 27/09; 26th Jan 2012 at 01:18.
is there such thing as Improved Vr for lighties
Now i'd uped the Vr number by 10 kts to get as close to Vy
Take Off Safety Speed
It's a speed with a safety factor over the stall speed.
It's a speed with a safety factor over the stall speed.
I've never seen TOSS as a term referred to in any light aircraft flight manuals that I've ever read. Is it just an Australian thing?
Any data I've seen refers to speed at 50'? Is this what's referred to here?
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Any data I've seen refers to speed at 50'? Is this what's referred to here?
For example, I have a flight manual for a single listing speeds based on weight for Vr (1.1 Vs1) follwed by speeds for 50' listed by weight as being 1.3Vs1. It is a TOSS because it provides the required safety margin over the stall as you accelerate towards Vx, Vy or cruise climb speed.
I look forward to hearing of any flight manual proposing increasing Vr beyond stated figures...
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VTOSS
Well despite my own view, i thought i'd stick my head in a book for ye.
This from Bob Taits VFR PPL Study guide
"TAKE-OFF SAFETY SPEED"
A take-off safety speed shall be established for each flap setting for which take-off distance information is to be provided. The take-off safety speed shall be an airspeed not less than 1.2 times the stalling speed and at which adequate control is available in the event of a sudden and complete engine failure during the climb following take-off
IIRC, both casa and manufacturers performance charts list this figure in the take off conditions box. (where there is no calculation provided). That being said, IIRC it is a certification req.
This from Bob Taits VFR PPL Study guide
"TAKE-OFF SAFETY SPEED"
A take-off safety speed shall be established for each flap setting for which take-off distance information is to be provided. The take-off safety speed shall be an airspeed not less than 1.2 times the stalling speed and at which adequate control is available in the event of a sudden and complete engine failure during the climb following take-off
IIRC, both casa and manufacturers performance charts list this figure in the take off conditions box. (where there is no calculation provided). That being said, IIRC it is a certification req.
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Captain Nomad.
I look forward to hearing of any flight manual proposing increasing Vr beyond stated figures...
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Just scanned a few SE POH's in my collection and it is worth making a point of noting that aside from stall considerations, it is usually recommended to fly the TOSS/50' spd until obstacles are cleared. Quite often this speed will be lower than the Vx speed (bear in mind that TOSS will take into account take off flap settings also). Increasing Vr and subsequently climbing at a faster speed (as in the original post) WILL serously jeopardise your obstacle clearance ability.
Take the 750XL pilot mentioned previously. Can't believe the nonsense of rotating at TOSS, but that aside, I wonder if he had memorized the speeds for weight variations? At 7500lb the book recomends Vr 61, TOSS 74. However at 4500lb that drops to Vr 49, and TOSS 59! Quite a big difference there. If he only used the stock max weight figures there could be an occasion at low weight where you are trying to hold on the runway for 25 kts beyond the recommend Vr for weight - preposterous! Someone like that needs to go and fly into some short bush strips where there are some solid 'incentives' to fly the poor plane properly...
Take the 750XL pilot mentioned previously. Can't believe the nonsense of rotating at TOSS, but that aside, I wonder if he had memorized the speeds for weight variations? At 7500lb the book recomends Vr 61, TOSS 74. However at 4500lb that drops to Vr 49, and TOSS 59! Quite a big difference there. If he only used the stock max weight figures there could be an occasion at low weight where you are trying to hold on the runway for 25 kts beyond the recommend Vr for weight - preposterous!
Someone like that needs to go and fly into some short bush strips where there are some solid 'incentives' to fly the poor plane properly...