Vanguard limiting speeds
Thread Starter
Remember that the MOD had to charter the civiliansed belslows to take outsized loads to Ascencion for the fleet during the Falklands war
"Mildly" Eccentric Stardriver
bean,
I'm not criticising the Belfast's carrying capacity. It was capable of carrying two Wessex helicopters, and five of them delivered ten Wessex to Changi in '70, as part of Operation Bersatu Padu.
I'm not criticising the Belfast's carrying capacity. It was capable of carrying two Wessex helicopters, and five of them delivered ten Wessex to Changi in '70, as part of Operation Bersatu Padu.
Herod , just to say your memory is correct .. Was taught in '74 to climb at 320kts IAS to FL 280 then at M0.80 upwards . FL280 being the crossover point . Had to wait 'til '82 to fly with Capt. Bill . Much later the ATP was akin to a 'Van in the flare , Those massive props gave you an effect of a blown wing , pull power back too early and propwash V squared , stopped the lift immediately , nose dropped and wing stopped flying , Thus Massive heave with feet on the dashboard.
Similar effects on 733 family . Big fan effectively blew the flaps , thus power reduced after round out commenced .
732s , S111s etc. power could be reduced before flare , wing kept flying [ Non blown wing/flaps ] as intake air came into engine well before the wing and exhaust air out well aft of the wing . Thus wing flew and a/c ' floated ' until momentum and lift decayed .
rgds condor .
Similar effects on 733 family . Big fan effectively blew the flaps , thus power reduced after round out commenced .
732s , S111s etc. power could be reduced before flare , wing kept flying [ Non blown wing/flaps ] as intake air came into engine well before the wing and exhaust air out well aft of the wing . Thus wing flew and a/c ' floated ' until momentum and lift decayed .
rgds condor .
condor17:
On the 732, that's not the whole story. The -ADV version would drop like a brick if you took power off before the flare, the basic -200 was more tolerant. Yes, that I did learn the hard way. There were significant differences in LE slat extension between the two, which probably accounted for the differing behaviour.
On the 732, that's not the whole story. The -ADV version would drop like a brick if you took power off before the flare, the basic -200 was more tolerant. Yes, that I did learn the hard way. There were significant differences in LE slat extension between the two, which probably accounted for the differing behaviour.
Thread Starter
Going right back the begining of my thread, Dixi188 and Megan gave us the Mne and Vne for the Electra. 0.615 and 364 knots It was also stated that the cross over point was 8000 feet
I've looked at the ISA tables and yes,
0.615 mach 8000 feet equals 8000 364 knots IAS. The profile is very similar to that in Discordes post descent in IAS 303 knots less 2 knots per thousand feet.
Herod, do you have the C130 limits to hand out of curiosity?
I've looked at the ISA tables and yes,
0.615 mach 8000 feet equals 8000 364 knots IAS. The profile is very similar to that in Discordes post descent in IAS 303 knots less 2 knots per thousand feet.
Herod, do you have the C130 limits to hand out of curiosity?
Last edited by bean; 7th Mar 2022 at 11:47.
"Mildly" Eccentric Stardriver
Sorry bean, I haven't. However, I'm certain that we never used Mach. The old girl wasn't that fast, so it was IAS, at least as far as I ever went in her. I think FL 310.
A point that may interest the readers: Many years ago I had a conversation with the test pilot who was tasked with clearing the Belfast for in-flight refuelling. He told me that it failed the trials as a result of the characteristics of the Tyne engine control response - I forget the details constant speeding versus RPM changes in the scheduling (unlike the C130) Perhaps someone can confirm this because many photos of the Belfast show them fitted with probes.
Thread Starter
A point that may interest the readers: Many years ago I had a conversation with the test pilot who was tasked with clearing the Belfast for in-flight refuelling. He told me that it failed the trials as a result of the characteristics of the Tyne engine control response - I forget the details constant speeding versus RPM changes in the scheduling (unlike the C130) Perhaps someone can confirm this because many photos of the Belfast show them fitted with probes.
The Tynes fitted to the CL-44 and Belfast produced 5730 SHP and drove 16 feet diamater props. What a beast!!!
The RAF pilots notes for the Belfast are available on flightmanualsonline.com.
Could make interesting reading for $9.95!
One of the Vanguard quirks I haven't seen mentioned is that X-winds from the right were easier than those from the left.
It was customary to initiate the flare with power on giving better flow over the elevator. When the throttles closed there was a yaw to the left which was helpful in a right x-wind but aggravated the effect from the left. I assumed this was gyroscopic effect of those huge props in the flare.
If you wanted a short landing you could close the throttles before the flare - provided you were ready for the necessary heave!
It was customary to initiate the flare with power on giving better flow over the elevator. When the throttles closed there was a yaw to the left which was helpful in a right x-wind but aggravated the effect from the left. I assumed this was gyroscopic effect of those huge props in the flare.
If you wanted a short landing you could close the throttles before the flare - provided you were ready for the necessary heave!
Explanation: In the northern hemisphere the surface wind is usually aligned a few degrees left of the wind aloft (due to friction partially reducing the Coriolis effect). In strong winds a gust temporarily increasing the surface wind will also bring about veering (clockwise directional change) due to the wind aligning more closely with the wind aloft. Therefore if an aircraft making an approach with a crosswind from the left encounters a gust the crosswind component will not greatly change - the veering offsetting the increased wind speed.
Conversely, a crosswind from the right will be trickier - the crosswind component will be increased by both of these factors: wind speed and veering. Other factors being equal, pilots making crosswind landings in the northern hemisphere will find crosswinds from the right more difficult than those from the left. In the southern hemisphere of course the opposite is true.
Just as well the Vibrator never ventured into the non-equatorial Southern hemisphere! Crosswind landings would have been trickier!
Explanation: In the northern hemisphere the surface wind is usually aligned a few degrees left of the wind aloft (due to friction partially reducing the Coriolis effect). In strong winds a gust temporarily increasing the surface wind will also bring about veering (clockwise directional change) due to the wind aligning more closely with the wind aloft. Therefore if an aircraft making an approach with a crosswind from the left encounters a gust the crosswind component will not greatly change - the veering offsetting the increased wind speed.
hence the swing
Conversely, a crosswind from the right will be trickier - the crosswind component will be increased by both of these factors: wind speed and veering. Other factors being equal, pilots making crosswind landings in the northern hemisphere will find crosswinds from the right more difficult than those from the left. In the southern hemisphere of course the opposite is true.
Explanation: In the northern hemisphere the surface wind is usually aligned a few degrees left of the wind aloft (due to friction partially reducing the Coriolis effect). In strong winds a gust temporarily increasing the surface wind will also bring about veering (clockwise directional change) due to the wind aligning more closely with the wind aloft. Therefore if an aircraft making an approach with a crosswind from the left encounters a gust the crosswind component will not greatly change - the veering offsetting the increased wind speed.
hence the swing
Conversely, a crosswind from the right will be trickier - the crosswind component will be increased by both of these factors: wind speed and veering. Other factors being equal, pilots making crosswind landings in the northern hemisphere will find crosswinds from the right more difficult than those from the left. In the southern hemisphere of course the opposite is true.
Nope - the yaw occured even on calm wind days!!
With counterclockwise rotating props there is a left rudder component needed to counter the inherent swing to starboard. When the throttles are closed the flight idle blade pitch severely reduced the rudder and fin authority hence the yaw to port.
Hi Meikleour
Where did the quoted 'hence the swing' come from? It wasn't in my post!
Summary: theoretical Vanguard landing in crosswinds in northern hemisphere: trickier right crosswind mitigated by left yaw effect described earlier. Southern hemisphere: trickier left crosswind exacerbated by yaw effect.
Where did the quoted 'hence the swing' come from? It wasn't in my post!
Summary: theoretical Vanguard landing in crosswinds in northern hemisphere: trickier right crosswind mitigated by left yaw effect described earlier. Southern hemisphere: trickier left crosswind exacerbated by yaw effect.
Also: the rudder when counteracting the yaw from the engines (which varied in accordance with power setting) was acting in a 'free stream' airflow - not greatly affected by the propwash itself, which meant that (contd. p94)
Discorde: Hi, I think we both agree that a) throttle closure resulted in a yaw to port and b) that your Coriolis Effect also applies but I was trying to get to the source of the yaw swing in the first place as described by Scotbill.
I think it is difficult to argue that the rudder was always acting "in a free stream airflow" when every power change needed a rudder/rudder trim input! Thus for every given thrust there was a compensating rudder position. Removing the aerodynamic balance suddenly with the props blanking much of the airflow removes the initial required rudder moment hence the swing (my quote) Remember how on take-off with full power and slow speed left nosewheel tiller was required because of the rotational airflow on the fin until the rudder became effective.
I think it is difficult to argue that the rudder was always acting "in a free stream airflow" when every power change needed a rudder/rudder trim input! Thus for every given thrust there was a compensating rudder position. Removing the aerodynamic balance suddenly with the props blanking much of the airflow removes the initial required rudder moment hence the swing (my quote) Remember how on take-off with full power and slow speed left nosewheel tiller was required because of the rotational airflow on the fin until the rudder became effective.
Hi Meikleour
We need an aerodynamics expert (which I'm definitely not) to sort this one out! I seem to recall that there are several reasons for variable engine power causing yaw changes, which rudder inputs oppose. On a single-engined aircraft one of the causes is spiral propwash past the fin-rudder but of course that doesn't apply to a multi with wing-mounted engines. Or does it? I wish I could remember . . .
We need an aerodynamics expert (which I'm definitely not) to sort this one out! I seem to recall that there are several reasons for variable engine power causing yaw changes, which rudder inputs oppose. On a single-engined aircraft one of the causes is spiral propwash past the fin-rudder but of course that doesn't apply to a multi with wing-mounted engines. Or does it? I wish I could remember . . .
As a comparison the Britannia performance figures are interesting.
General characteristics
General characteristics
General characteristics
- Crew: 4–7
- Capacity: 139 passengers (coach class)[84]
- Length: 124 ft 3 in (37.87 m)
- Wingspan: 142 ft 3 in (43.36 m)
- Height: 37 ft 6 in (11.43 m)
- Wing area: 2,075 sq ft (192.8 m2)
- Airfoil: root: NACA 25017; tip: NACA 4413[85]
- Empty weight: 86,400 lb (39,190 kg) [84]
- Max takeoff weight: 185,000 lb (83,915 kg)
- Powerplant: 4 × Bristol Proteus 765 turboprop engines, 4,450 shp (3,320 kW) each equivalent
- Propellers: 4-bladed
- Maximum speed: 397 mph (639 km/h, 345 kn) [86]
- Cruise speed: 357 mph (575 km/h, 310 kn) at 22,000 ft (6,706 m)
- Range: 4,430 mi (7,130 km, 3,850 nmi)
- Service ceiling: 24,000 ft (7,300 m) [87]
Specifications (Type 952)
Data from Vickers Aircraft since 1908[33]General characteristics
- Crew: 3
- Capacity: 139 passengers
- Length: 122 ft 10+1⁄2 in (37.452 m)
- Wingspan: 118 ft 0 in (35.97 m)
- Height: 34 ft 11 in (10.64 m)
- Wing area: 1,527 sq ft (141.9 m2)
- Empty weight: 85,000 lb (38,555 kg)
- Gross weight: 141,000 lb (63,957 kg)
- Powerplant: 4 × Rolls-Royce Tyne RTy.11 Mk 512 turboprops, 5,545 shp (4,135 kW) each (eshp)
- Cruise speed: 422 mph (679 km/h, 367 kn) at 15,000 ft (4,600 m) (high speed cruise)[34]
- Range: 1,830 mi (2,950 km, 1,590 nmi) with maximum payload
More on the propwash/ yaw subject (or propwash/ yawn, some of you might say):
When the engines are producing thrust each engine is generating a spiral airflow, with the upper prop blades generating an overall lateral flow in one direction (right to left in the case of the Vanguard/ Tyne config) and the lower blades the opposite direction. The upper lateral flow will clearly impinge on the right rear fuselage and tail more so than the lower flow, imparting a yawing motion (to the right on the Vanguard), requiring a left rudder input to cancel.
When reduced to flight idle thrust the lateral flow from the props will disappear, meaning that the left rudder input countering the approach thrust throttle setting will now cause a yaw to the left, as Scotbill and Meikleour described.
Another factor (contd. p94)
Thread Starter
on the taxy in, 2 and 3 are idling certainly but, i never saw a BEA Vanguard shutting engines down during taxy
Great graphics Discorde!!
D P Davies ( aka HTBJs ) in his radio talks makes mention of an "along wing airflow" on four engined prop aircraft which invariably leads to some nasty stalling characteristics, hence the admonishment with the Vanguard to "not progress the stall beyond the initial buffet". Ron Gillman in his excellent book Croydon to Concord describes such an incident and probably explains why the subject airframe never seemed to fly "true" afterwards.
D P Davies ( aka HTBJs ) in his radio talks makes mention of an "along wing airflow" on four engined prop aircraft which invariably leads to some nasty stalling characteristics, hence the admonishment with the Vanguard to "not progress the stall beyond the initial buffet". Ron Gillman in his excellent book Croydon to Concord describes such an incident and probably explains why the subject airframe never seemed to fly "true" afterwards.
