Lifting Nosewheel on T/O - Why So?
V1 and V2 are not quite the same as decision and rotate. I guess V1 does equate to decision speed, ie you're no longer going to be able to stop. V2 is the nominated speed to fly once airborne but still with any take-off flap in the event of an engine failure. It's effectively your best climb-angle speed and used until you reach your acceleration altitude.
I guess raising the noisewheel was used on types which were flown off the runway as opposed to being rotated more aggressively and 'hauled' off. Ie, once the nosewheel is up the aircraft will then fly itself off the runway when ready.
I guess raising the noisewheel was used on types which were flown off the runway as opposed to being rotated more aggressively and 'hauled' off. Ie, once the nosewheel is up the aircraft will then fly itself off the runway when ready.
Not in the same class I know, but for takeoff in the Shadow microlight, you commence with the sidestick pulled right back until the nosewheel lifts, then ease forward to maintain a positive angle of attack(and avoid the tail bumper striking) . The aircraft flies itself off when ready at about 70 kt.
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V2 is the speed that you will reach (all engines operating) at the screen height of 50' (old types) or 35' (newer types). It is also the speed at which: " A sufficient margin of control exists for the average pilot with the a/c in the T/O configuration (ie flap) to maintain directional control whilst achieving the maximum climb angle following failure of the most critical engine."
Sleeve Wing , concur with avoiding water / slush /snow ingestion . We used same technique on all marks on Trident .
In those conditions ,
''V1'' called and is stop /go decision speed .
''Rotate'' called at rotate speed [ Vr ] .
''V2'' is engine out safety speed . In wet conditions , gives a screen height of 15 feet! Talk to BAC111 crew out of Basel on a wet day with and engine failing after V1 ...
With the modern twins , they are mostly way over powered in the 2 engine t/o case , and thus very often V1 = Vr .
rgds condor .
In those conditions ,
''V1'' called and is stop /go decision speed .
''Rotate'' called at rotate speed [ Vr ] .
''V2'' is engine out safety speed . In wet conditions , gives a screen height of 15 feet! Talk to BAC111 crew out of Basel on a wet day with and engine failing after V1 ...
With the modern twins , they are mostly way over powered in the 2 engine t/o case , and thus very often V1 = Vr .
rgds condor .
TTN #12
IIRC the Victor K1/1A used "Go Speed" and "Stop Speed", usually in the correct order or simultaneous at Marham. On Trails, in places like Masirah, it was not unusual to have to accept a 10 knot gap between "Stop Speed" and "Go Speed" to lift the required fuel load. Not Perf A !!
A couple of thoughts( not knowledge ) about lifting the nosewheel early. Was this a technique required by the early tricycle undercarrige on such as the Airacobra, and taught to us by the Americans? This was then carried over to the early jets as "that was the way to do it" with tricycle undercarriage.
Nosewheel tyre speed limits could also have been a problem. Certainly with the Canberra, but could also be limiting with the VC10 at high elevation places like Nairobi. IIRC the limit was 200 MPH!
IIRC the Victor K1/1A used "Go Speed" and "Stop Speed", usually in the correct order or simultaneous at Marham. On Trails, in places like Masirah, it was not unusual to have to accept a 10 knot gap between "Stop Speed" and "Go Speed" to lift the required fuel load. Not Perf A !!
A couple of thoughts( not knowledge ) about lifting the nosewheel early. Was this a technique required by the early tricycle undercarrige on such as the Airacobra, and taught to us by the Americans? This was then carried over to the early jets as "that was the way to do it" with tricycle undercarriage.
Nosewheel tyre speed limits could also have been a problem. Certainly with the Canberra, but could also be limiting with the VC10 at high elevation places like Nairobi. IIRC the limit was 200 MPH!
Sleeve Wing,
Instead of your DC-9's water deflector on the nose gear, the VC10 and BAC 1-11 nose-wheel tyres had integral chines to deflect water downwards. That reduced water ingestion into the engines, but obviously did not protect them from burst-tyre debris...
H Peacock,
Love your description of aggressive rotation and aircraft being "hauled off" the runways nowadays! In fact, a steady rotation rate of about 3 degrees per second is typical, to avoid tail-scrape on long-body types.
Last edited by Chris Scott; 20th Apr 2018 at 16:56. Reason: Last sentence added.
Surely the nose is lifted to increase the angle of attack, and thus get the thing to fly in the first place?
Chris Scott
As far as I remember the RAF VC10s were limited by Nosewheel speeds rather than Mainwheel speeds. I will not argue about the actual figures as I have not made an ODM calculation for 20 years and do not have one to hand.
Perhaps BEagle can throw some light on this.
As far as I remember the RAF VC10s were limited by Nosewheel speeds rather than Mainwheel speeds. I will not argue about the actual figures as I have not made an ODM calculation for 20 years and do not have one to hand.
Perhaps BEagle can throw some light on this.
, the T/O performance would have had to be predicated on a 200 mph (174 kt) max ground-speed, even if the main-wheel tyres had the 225 mph rating. The operation I was referring to was in the early 1970s, but maybe by the 1990s or later the manufacturer was no longer offering the special nose-wheel tyres with "chines" for the VC10 with the 225 mph rating. (The main-wheel tyres did not have chines.)And, returning to topic, lifting the nose-wheels off the runway prior to VR increases aerodynamic drag and is therefore not an option to improve performance.
You RAF guys ended up operating almost every original type of VC10 (albeit modified in most cases) except the one that I did. You must have had many different sets of graphs or tables - or was it all computerised?
Maybe some brilliant person reckoned that if a tail-dragger had to lift the tail on takeoff roll, then a nose-wheeler had to lift the nose?
Thread Starter
Was this a technique required by the early tricycle undercarrige on such as the Airacobra, and taught to us by the Americans? This was then carried over to the early jets as "that was the way to do it" with tricycle undercarriage.
B-29 says to relieve pressure on the nosewheel at 90 mph to lengthen the oleo. Nosewheel should not be more than one inch off the runway at any point in the roll and aircraft will fly itself off.
Notes on the P-38 mention a negative angle of attack and at 80 mph pull back steadily and firmly for lift off at 100 mph.
Vascodegama.
Thanks for the endorsement that I have not (yet) lost all my faculties. However, down here it is normally chilled Rose rather than Vin rouge, due to the sun and high temperatures. At the moment I am sipping chilled Guinness. I have just returned from a trip to Spain with a couple of cases. Unfortunately I was not able to organise a tanker!
Chris Scott
The RAF had the VC10CMk1, which was the new aircraft for 10 Sqn. These were a Hybrid with Standard (ie short) body and Super wings. These had the ODMs for the type. When we acquired the Tanker aircraft we had old BOAC/Gulf Air Standards as K2s and Old East African Airways Supers as K3s. All the aircraft had the same standardised engines.
The Tanker ODMs were produced to different standards to the original RAF VC10 C1s, and did not cover the same operating limits (more limiting) as it was not envisaged that we would operate worldwide, thereby saving a couple of quid in their production.
The ODM was produced for the K2(Standard) with fiddle factors to be applied to the K3. The K4(Ex BA Supers) had the same performance as the K3s.
We had Regulated TakeOff Graphs(RTOGs) produced, for the various types,
at selected airfields as well as Balanced Field Graphs you could use if Max TOW was not a problem.
If you had to operate at MTOW from an airfield that was not in the book of RTOGS it was back to struggling with the ODM.
Thanks for the endorsement that I have not (yet) lost all my faculties. However, down here it is normally chilled Rose rather than Vin rouge, due to the sun and high temperatures. At the moment I am sipping chilled Guinness. I have just returned from a trip to Spain with a couple of cases. Unfortunately I was not able to organise a tanker!
Chris Scott
The RAF had the VC10CMk1, which was the new aircraft for 10 Sqn. These were a Hybrid with Standard (ie short) body and Super wings. These had the ODMs for the type. When we acquired the Tanker aircraft we had old BOAC/Gulf Air Standards as K2s and Old East African Airways Supers as K3s. All the aircraft had the same standardised engines.
The Tanker ODMs were produced to different standards to the original RAF VC10 C1s, and did not cover the same operating limits (more limiting) as it was not envisaged that we would operate worldwide, thereby saving a couple of quid in their production.
The ODM was produced for the K2(Standard) with fiddle factors to be applied to the K3. The K4(Ex BA Supers) had the same performance as the K3s.
We had Regulated TakeOff Graphs(RTOGs) produced, for the various types,
at selected airfields as well as Balanced Field Graphs you could use if Max TOW was not a problem.
If you had to operate at MTOW from an airfield that was not in the book of RTOGS it was back to struggling with the ODM.