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?

No benefit. Aeroplanes accelerate in the air too. Pull the nosewheel a little off the ground and it'll fly when it wants to.

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.

"Arrow"!

Said it all, really!

Dr :8

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.:hmm:

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

This actually sounds right for the conditions and what you were doing. The total take-off distance from the book (unfactored) indicates a little over 1000m required, thats with a TOSS of 69KIAS and clearing a 50ft barrier. Throw in the factors of old aircraft, lazy old engine, couple of bugs on the wing, few knicks out of the prop, actuall weight maybe slightly more than factored.

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.

I too flew an Arrow once....wouldn't pull a sick whore off a pi$$pot!

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.

Another reason to spend some time on tailwheel a/c. If you get her tail up and hold her on the mains for too long she may well start bouncing; letting you know full well she's ready and you're not. Why not? You're not feeling.

Good point os, great extension lumps' post. :ok:

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.

-----------------------------------------------------------

Don't get me started on the old Casa charts :ugh: 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 :ugh::ugh:

Worst change i have seen! (other than juliar)

Old CASA charts.:ok:

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!:ooh: 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

http://www.casa.gov.au/newrules/part.../ac091-225.pdf

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.

Take Off Safety Speed

It's a speed with a safety factor over the stall speed.

Lighties? Do you fly heavies as well??? Perhaps darkies?

As a few before me have asked, where did the rationale of upping the Vr number come from? What sort of instructor do you have? If you keep this nonsense up perhaps catering again may be a good call.

What is the factor?

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?

Yes, and as dangnamit said, it is a caclulated speed with a stall buffer. In most cases 1.3 Vs1.

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... :suspect:

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.

Captain Nomad.
 

I do also. Its either stated as a figure, or stated as a formula. You won't find the formula stated for lighties. Some perf charts do give you a resultant speed to use, but the formula is written into the diagram, so i'd call it a listed figure.

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! :ooh: 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...

This is where the rotating at TOSS nonsense comes from. Day VFR syllabus, page 2-32 Unit A2 Take off aeroplane.
Element A2.2
• Accelerates aircraft along the centreline to the take-off safety speed,
allowing for wind
• Rotates aircraft to the target climb attitude at approximately 3° per
second

Also, I forgot to finish a sentence in a earlier post. Dinner was ready.

There are some instructors at Moorabbbin that teach their students to hold Seminoles on ground until blue line before rotating!http://images.ibsrv.net/ibsrv/res/sr...ies/icon25.gif 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 nose gear collapse incidents and resulting AD that followed.

Where do people get this sh!t from?

They should go fly a twin in PNG! :E

....or find themselves a paddock somewhere without too many stumps and do some limited MAP/RPM take offs.

ROFL!!!
 

Blue line? seriously?
in a smellymole?

http://www.mustangtech.com.au/images...t-flashfap.gif

The only number to worry about in a smellymole is Vmca....oops you accelerate through that before the bugger will fly anyway http://www.mustangtech.com.au/images/smiles/poking.gif

And what ever happened to accelerating in ground effect :confused:

Cripes, even a trouble-air will happily accellerate to Vx without its feet being on the deck. :D

Nomad, can't see any logic in flying at any speed other than Vx for obstacle clearance, especially if that speed is less than Vx.:confused:

TOSS is normally set as 1.2 Vs in the takeoff config. Bear in mind Vs changes with weight, so short of having a card with varying speeds for weights on it (assuming your a/c has a wide enought range of weight to worry about it), why not refer to the POH?

I agree with post #24. Get the wheels a couple feet off the runway and accelerate in ground effect.

MakeItHappenCaptain, I agree that Vx is normally the climb that you are looking to establish for obstacle clearance.

However, in the takeoff scenario, if you reference the POH as you say, a number of POH's will actually advise you to maintain TOSS until obstacles are cleared on take off for a performance/short field takeoff scenario. Makes sense really.

Take a bigger single like the 750XL for example. Zero flap Vx is 85 kts. All take offs require a 20 degree flap config. For a performance take off with 20 degree flap it is recommended to initially climb at 74 kts (this is the max weight TOSS and it refers you to the Performance section for TOSSs to use at lower weights - it can be as low as 59 KIAS at 4500lb) until clear of obstacles. You don't want to be retracting flap and accelerating to Vx 85 kts and plowing into trees until you have climbed above the obstacles in the initial climb phase.

A quick look at something smaller like a Warrior II POH expresses similar concepts for obstacle clearance on all take offs. Take the 25 degree (two notches) flap take off for example. Piper says: "40-52kts (depending on weight) back pressure to rotate to climb attitude. Accelerate to and maintain 44 to 57 kts (TOSS, Piper calls it '50 ft barrier' speed, depending on weight) until obstacle clearance is achieved and climb out at 79 kts (Vy). Retract flap slowly."

The reality is, most of the time we are not faced with a scenario where we are wanting to squeeze the last drop of performance out of our machine so we take off, clean up and cliimb at Vx if we feel like it for a best angle climb. But according to what your manufacturer recommends, if you want the best take off performance you will fly it by the book speeds and instructions. At the very least, certainly common sense should tell you that to change the take off configuration (eg raising flap) before safely clearing obstacles will only lead to tears (or some tense pucker moments if you are really lucky)!

Seems to be some confusion between clean and flap-down Vx. If taking off with flap, use the appropriate Vx (or Vy), which is will certainly be less than the clean Vx (or Vy).

As Capt Nomad said, the manufacturer provides the best numbers to use. In light Cessna and Piper aircraft, the manufacturer's quoted TOSS's are actually pretty close to Vx anyway for that configuration. (Not quite identical though.)

In light aircraft I generally found that the attitude for Vx (or Vy) climbs was very similar across all take-off flap settings, once clear of ground effect. Very helpful if you want to avoid chasing the airspeed indicator in a steady climb.

Now in those immortal words from Capt to FO: "take off flap please".

Hot, High or Heavy............more TOD required. Pretty basic stuff.There are some instructors at Moorabbbin that teach their students to hold Seminoles on ground until blue line before rotating! Christ they're aircraft not fu**ing race cars. Who is teaching this sh*t???

Looking at the POH for C172P model - can see a fair parallel between TOSS and Vx.

Cessna quote 60KIAS in section 4.3 - but in section 4.8 they use 56KIAS. Probably easier to eyeball the 60 mark on an analog ASI though.

There are some discrepancies in TOSS in the POH though:

* in the general notes, (4.8), Cessna quote 56KIAS as TOSS
* by calculation, using 49 as the 10 degree Vs - you get 49 x 1.2 = 59KIAS

Probably not even noticeable in practice though?

One interesting note is that they state you gain 10% by using 10 deg flap for t/o - which is why I've only used that stall speed for calcs.

Of interest to this thread is that the 'lift nosewheel' recommendation is actually in the C172 POH. ie, there is a Vr implied.....or are we being too strict in our read of the POH?

In section 4.8, it's stated to lift nosewheel at 55KIAS. But, elsewhere they use 56KIAS as their general TOSS number. Using the 10 deg flap stall speed of 49K - you can calculate a Vr of 54K, (x 1.1).

Using zero flap, you can calculate a Vr of 57, and will quickly reach a calc TOSS of 62 before reaching the 50ft barrier, and from there you may as well accelerate thru to Vy (76).

Conclusion - provided your runway is smooth, then Vr might be acceptable - but in real life strips, forget the Vr calculation and get your nosewheel lifted early. Doesn't prevent you complying with other speeds such as TOSS, Vx, and Vy though.

happy days,

Take care when calculating factors for Cessna aircraft. Pressure error is very large - in the order of 10kts at Vs from memory.

If pilots want to factor by 10% or 20%, use CAS not IAS. You can use the pressure error chart in the flight manual to convert back to IAS. Yes, it does make a difference in Cessna aircraft.

Example, using random numbers.
Vs is 48 KIAS. Pressure error at this speed 8kts. 56 KCAS x1.2 = Vx 67 KCAS. Pressure error is 6kts. Vx is 61 KIAS.

Nomad and Oktas, well picked. Was actualy hoping another user was going to spot this one first. (Most here know I'm a fan of POHs.)
Your response about retracting flap and losing performance is bang on. Slight thread drift, but sure PACs and 208s behave similarly during EFATO turnbacks. Even going from 10 deg flap to 0 causes a MASSIVE performance loss.

Ahh the old ones are the best ;)
 

Back in 2001, we were talking (in a more erudite fashion, I might ad ;) ) about this:
http://www.pprune.org/tech-log/9523-...eed-aztec.html

.. and again in 2003:
http://www.pprune.org/dg-p-general-a...n-trouble.html

:ok:

Multi-engine aircraft are divided by FAR 23 into two weight classes - above and below 6000lbs, and those below 6000lbs are divided into two classes depending on Vso (stall speed in the landing configuration) above and below 61 knots CAS.

Only those twins that weigh more than 6000lbs or have a Vso higher than 61 knots need to demonstrate any single-engine climb performance at all for certificaion, and the requirements are pretty meager. Basically the regulation says that these aircraft must demonstrate a single engine capability at 5000' (ISA) with the inop engine feathered and in a clean configaration.

The only requirement for an aircraft less than 6000lbs, and with a Vso less than 61kts (like the Aztec) is that its climb performance (positive or negative) be determined.

There is nothing in the FAR which says an aircraft must fly while in the take-off configuration with one engine inop.

Talking about rotation, manufacturers tend to have a philosophy about this that shows up in in the aircraft design, wing incidence and gear positioning.

Piper recommends that most twins be rotated at Vmc, Cessna on the other hand suggests a lift off at a speed much higher than Vmc and very close to best single-engine angle of climb speed. In the case of a C-310, Vmc is 75 knots, recommended rotation speed is 91 knots and best single engine angle of climb speed is 94.

Try and hold a Seneca or Aztec on the ground much beyond Vmc plus 5 knots (zero flap) and the aircraft will begin to wheelbarrow! Cessna twins (and most cabin class twins) will happily stay on the ground for much longer than that.

A Navajo for instance (stretching the old memory) will happily go by road, if you don't positively rotate it - you hardly have to "force the aircraft on the runway well past VR and until a few knots past Blue Line"!

I would rotate a light (FAR 23) twin not below Vmc+5 (or the recommended rotate), and I pull the gear up just after getting airbourne, then climb at the best all engine climb rate (which is faster then blue line) until clear of obstacles in the area.

CAA performance
 

CB - Do the Brits still have the performance 'Class" system for aircraft and the examaination for it??.

The Perf A was a bugger, but as I remember Class C was the PA 31/ P166 etc. and so on.

Sorry about the slight drift, but curious.

EU-Ops.

From memory:
Class A - defined performance for continued flight after EF at V1. A is for Airliner.
Class B - no specific performance required at any stage of flight following an engine failure. B is for Bugsmasher.
Class C - large or heavy or turbojet aircraft that really should be in Class A, but lack the OEI performance. C is for Classic aeroplane, think DC3.

I don't recall the precise weight / seat numbers / powerplant requirements that distinguish the categories.

Certification V speeds vs real world
 

I know, same guy again - but clearly someone that thinks for themselves and has flown all the good stuff, C-46, B-29, DC-3, P-51 etc etc.

So while we're on the subject:

Pelican's Perch #22:<br>Short- and Soft-Field Takeoffs — FAA vs. Reality

Good article. I remember many a conversation with Russ Evans about 'certification' flying vs 'real world flying.' Anyone else who has done an instructor renewal with him will probably also remember as it is one of his pet subjects - especially with regard to multis also.

This quote is what I was getting at earlier:
Having flown in this environment with soft fields, short fields, and fields with crazy slopes and obstacles, one way strips with tailwinds etc. this advice is very much worth paying attention to. Even seasoned bush pilots can get undone on this one and a P-Chart determined TOW could kill you:
One bit that he mentions regarding 'cleaning up' I would like to add a caution note to:
One of the things that really ticks me off these days is seeing people take off on a long runway in a single-engine retractable gear machine and wouldn't you know? The wheels have barely left the runway and already they are being retracted! On most runways this just simply isn't necessary. I know of a fellow in the States who belly landed and damaged a perfectly good Bonanza back on a huge runway after having the proverbial 50' engine failure. If he had just left the wheels down there would have been NO damage at all. Leave this bit of performance advice to when you really need it - don't do it as standard practice all the time on long runways with low-level density altitudes. There is absolutely no advantage in doing so.

Oooooh, ah dunno about that..:ooh:

Unless yer in a chopper i woulda thought its better to practice the more 'involved' stuff on a nice big bitumen runway. Though i'm not an instructor, so...




.

If yer operating to some demanding airstrips at times wouldn't it be better to make it a 'standard practice' so its just what yer do every flight ? - Less distractions then.




.

So you are in a 210 at YSSY taking off from 34L Even if you have been given a departure from 07/25 you still have shed loads of room. You raise the gear at 30ft because that's how you do it out bush. 50 feet you have an engine failure. You now have to get the plane on the ground under control and get the gear out?

Hell I've taken 182s with retractables out of places like Albury or Canberra and been a couple hundred feet and still with runway and clearway underneath me. I'd sure rather have the gear down so all I have to do is push the nose forward when the donk dies!

:ok: Yes the above examples are simplified and exaggerated but the principal works.