Are Vulcans good at gliding?
Discussion
As the topic title says, really; perhaps more specifically, did Vulcan pilots ever need or choose to glide in order to save fuel, or in emergencies? If so, could these events be considered common?
It must be a spectacular event to have one sneak up on you, but was gliding a Vulcan ever an option?
It must be a spectacular event to have one sneak up on you, but was gliding a Vulcan ever an option?
Eric Mc said:
Any aeroplane will glide - up to a point.
...even 747s.http://en.wikipedia.org/wiki/British_Airways_Fligh...
I COMPLETELY know that - as long as the APU's still running, there are some aircraft which don't like the human touch. And I don't think any F104 pilot would say, hmm, went a bit mad with the afterburner there, better switch it off for 30 seconds or so...
Anyway:
The Vulcan - was it ever glided to save fuel/sneak up on anyone from behind?
I KNOW about radar; it was a joke. Forget the behind bit.
Okay...ahem:
Was it an option or an unwritten rule left to the discretion of the crew that the aircraft could be 'glid' in the event of an event which required them to save more fuel than they had planned?
Y/N?
Mrs G. Fifteen?
(edited to change 'afternuner' to 'afterburner' but in hindsight I should have left it).
Anyway:
The Vulcan - was it ever glided to save fuel/sneak up on anyone from behind?
I KNOW about radar; it was a joke. Forget the behind bit.
Okay...ahem:
Was it an option or an unwritten rule left to the discretion of the crew that the aircraft could be 'glid' in the event of an event which required them to save more fuel than they had planned?
Y/N?
Mrs G. Fifteen?
(edited to change 'afternuner' to 'afterburner' but in hindsight I should have left it).
Edited by 205alive on Tuesday 3rd September 21:21
205alive said:
I COMPLETELY know that - as long as the APU's still running, there are some aircraft which don't like the human touch.
Anyway:
The Vulcan - was it ever glided to save fuel/sneak up on anyone from behind?
I KNOW about radar; it was a joke. Forget the behind bit.
Okay...ahem:
Was it an option or an unwritten rule left to the discretion of the crew that the aircraft could be 'glid' in the event of an event which required them to save more fuel than they had planned?
Y/N?
Mrs G. Fifteen?
Fixed Delta wings, are relatively inefficient (therefore not as good for gliding) at low speeds, than conventional fixed wing designs. They are less draggy (therefore more suitable for high speed flight) than coventional fixed wing designs. This is why a lot of military aircraft used 'variable geometery' (sweep wings). They get stability for take off and landing, and lower drag / better manouverablity (than fixed wing) at high speeds.Anyway:
The Vulcan - was it ever glided to save fuel/sneak up on anyone from behind?
I KNOW about radar; it was a joke. Forget the behind bit.
Okay...ahem:
Was it an option or an unwritten rule left to the discretion of the crew that the aircraft could be 'glid' in the event of an event which required them to save more fuel than they had planned?
Y/N?
Mrs G. Fifteen?
Gwagon111 said:
Fixed Delta wings, are relatively inefficient (therefore not as good for gliding) at low speeds, than conventional fixed wing designs. They are less draggy (therefore more suitable for high speed flight) than coventional fixed wing designs. This is why a lot of military aircraft used 'variable geometery' (sweep wings). They get stability for take off and landing, and lower drag / better manouverablity (than fixed wing) at high speeds.
Yes, but - the Vulcan - I would have thought the massive chord would've made for a great lift to weight ratio.Anyway, thanks for the lesson.
205alive said:
I would have thought the massive chord would've made for a great lift to weight ratio.
lift is concentrated at a certain point on the wing. 1/3 of the chord or thereabouts [aerofoil dependent]. for high lift you want to maximise the area over which this acts, so you want a wide wingspan and a short chord. Despite what others have said, a Delta wing is actually quite good at low speed, compared to a swept wing, owing to vortex generation at high alpha. Additionally it has a large wing area giving a relatively low wing loading.
At first sight then, you might think a Vulcan would glide well but, being a delta, it is very sensitive in pitch in the sense that a very small change in pitch angle results in a massive rise in drag. Additionally the nature of the high induced drag of any delta means that it rapidly bleeds energy in a turn. Coupled with this, the tailless delta of the Vulcan means that there is a drop in total available lift as soon as the trailing edge control surfaces are displaced from the neutral position.
I'd therefore imagine its gliding qualities would be poor.
While the Vulcan had an APU to give electrical power in the case of engine failure below 30,000ft and a Ram Air Turbine for use above 20,000ft, switching off all 4 engines in flight would cause the loss of a lot of systems including the hydraulic flying controls (let alone the problems of having to windmill start the engines).
I'd suggest that gliding it wasn't an option!
At first sight then, you might think a Vulcan would glide well but, being a delta, it is very sensitive in pitch in the sense that a very small change in pitch angle results in a massive rise in drag. Additionally the nature of the high induced drag of any delta means that it rapidly bleeds energy in a turn. Coupled with this, the tailless delta of the Vulcan means that there is a drop in total available lift as soon as the trailing edge control surfaces are displaced from the neutral position.
I'd therefore imagine its gliding qualities would be poor.
While the Vulcan had an APU to give electrical power in the case of engine failure below 30,000ft and a Ram Air Turbine for use above 20,000ft, switching off all 4 engines in flight would cause the loss of a lot of systems including the hydraulic flying controls (let alone the problems of having to windmill start the engines).
I'd suggest that gliding it wasn't an option!
Edited by Ginetta G15 Girl on Tuesday 3rd September 21:51
A bit of googling turns up a number of 16.8 for the Vulcans L/D maximum (lift to drag ratio).
Assuming this is in an unloaded condition with little trimming, i bet a fully bomb loaded and trimmed version on a long range (heavy fuel load) flight would be a lot lot worse than that (perhaps down in the 12s at a guess)
berkeley edu aero paper
see slide 7
Assuming this is in an unloaded condition with little trimming, i bet a fully bomb loaded and trimmed version on a long range (heavy fuel load) flight would be a lot lot worse than that (perhaps down in the 12s at a guess)
berkeley edu aero paper
see slide 7
shirt said:
lift is concentrated at a certain point on the wing. 1/3 of the chord or thereabouts [aerofoil dependent]. for high lift you want to maximise the area over which this acts, so you want a wide wingspan and a short chord.
That's not strictly true.While the Centre of Lift acts at about 1/3 of the Chord, that is not to say the rest of the wing does not produce lift!
A High Aspect Ratio wing such as you describe (long and thin) has nothing do do with high lift per sé but everything to do with increasing the Lift : Drag ratio because it delays the onset of, and reduces, the wingtip vortices and therefore reduces the overall Induced (Lift Dependent) Drag.
That is why such wings are used on high performance sailplanes.
Ginetta G15 Girl said:
Despite what others have said, a Delta wing is actually quite good at low speed, compared to a swept wing, owing to vortex generation at high alpha. Additionally it has a large wing area giving a relatively low wing loading.
At first sight then, you might think a Vulcan would glide well but, being a delta, it is very sensitive in pitch in the sense that a very small change in pitch angle results in a massive rise in drag. Additionally the nature of the high induced drag of any delta means that it rapidly bleeds energy in a turn. Coupled with this, the tailless delta of the Vulcan means that there is a drop in total available lift as soon as the trailing edge control surfaces are displaced from the neutral position.
I'd therefore imagine its gliding qualities would be poor.
While the Vulcan had an APU to give electrical power in the case of engine failure below 30,000ft and a Ram Air Turbine for use above 20,000ft, switching off all 4 engines in flight would cause the loss of a lot of systems including the hydraulic flying controls (let alone the problems of having to windmill start the engines).
I'd suggest that gliding it wasn't an option!
Thanks, that's quite a detailed explanation. I much prefer it over the 'Y/N' I demanded earlier.At first sight then, you might think a Vulcan would glide well but, being a delta, it is very sensitive in pitch in the sense that a very small change in pitch angle results in a massive rise in drag. Additionally the nature of the high induced drag of any delta means that it rapidly bleeds energy in a turn. Coupled with this, the tailless delta of the Vulcan means that there is a drop in total available lift as soon as the trailing edge control surfaces are displaced from the neutral position.
I'd therefore imagine its gliding qualities would be poor.
While the Vulcan had an APU to give electrical power in the case of engine failure below 30,000ft and a Ram Air Turbine for use above 20,000ft, switching off all 4 engines in flight would cause the loss of a lot of systems including the hydraulic flying controls (let alone the problems of having to windmill start the engines).
I'd suggest that gliding it wasn't an option!
Edited by Ginetta G15 Girl on Tuesday 3rd September 21:51
Something you state makes me think about inherent innstability overridden by mucho hp - when you say:
"there is a drop in total available lift as soon as the trailing edge control surfaces are displaced from the neutral position"
would this, in the case of the Vulcan, make it more susceptible to stall - which could be 'capitalised on' by overriding the stall with the huge power output?
What I'm trying to get at is, this drop in total lift - could the pilot make it flick up sharply and pre-empt the loss of lift by giving it a welly full of throttle in order to get a high G manouver?
Or am I just completely grabbing the wrong end of the control column? It's just that they appear to have a reputation for being incredibly agile for the size - or are they just incredibly agile?
Big delta's don't "stall" in the classical sense. They pretty much continue to produce positive lift of some form or other, without a sudden and marked airstream seperation at high AOA's. But, and it's an important but, the total drag of the craft increases enormously as speed falls below a certain threshold(As the large wing area gets presents to the airflow at a more and more "plan" angle as positive pitch increases) . This makes it important for the powerplant to produce a high thrust co-efficient at low speed to be able to overcome this increase in drag.
Max_Torque said:
Big delta's don't "stall" in the classical sense. They pretty much continue to produce positive lift of some form or other, without a sudden and marked airstream seperation at high AOA's. But, and it's an important but, the total drag of the craft increases enormously as speed falls below a certain threshold(As the large wing area gets presents to the airflow at a more and more "plan" angle as positive pitch increases) . This makes it important for the powerplant to produce a high thrust co-efficient at low speed to be able to overcome this increase in drag.
Of course - yes - now you've jogged my memory, I've watched hang gliders as a kid and noticed a nice mushy transition through the stall and into recovery - likewise, flying wings seem to be inherently benign/stable.What I was getting at is that all aircraft will "glide". But, obviously, some glide better than others.
The Space Shuttle is a very good exampole of a pretty rotten glider - but the whole design was based on the fact that it made a completely unpowered approach and landing. In other words, it was a glider.
And it was essentially a delta.
The Space Shuttle is a very good exampole of a pretty rotten glider - but the whole design was based on the fact that it made a completely unpowered approach and landing. In other words, it was a glider.
And it was essentially a delta.
Some interesting V bomber stuff here:
V-Trials flying
(BTW, the SST's average L/D for the typical descent profile is around about 4.5 apparently. It pretty much 'flies' like a brick! Luckily, it always starts it's descents with quite a lot of potential energy.............)
V-Trials flying
(BTW, the SST's average L/D for the typical descent profile is around about 4.5 apparently. It pretty much 'flies' like a brick! Luckily, it always starts it's descents with quite a lot of potential energy.............)
Edited by anonymous-user on Tuesday 3rd September 22:33
Edited by anonymous-user on Tuesday 3rd September 22:33
Gassing Station | Boats, Planes & Trains | Top of Page | What's New | My Stuff