Light Aircraft Crash in Oxfordshire
Got about 600 hrs. on the PA30/’39. I wouldn’t like to lose one in IMC ; even more so with high ambient pressure situation.
SE Climb speeds have got to be nailed to get any ROC at all. In a turn (away from the high ground), of course, more of a problem.
More than experience, luck’s got to be on your side too. Very sad.
SE Climb speeds have got to be nailed to get any ROC at all. In a turn (away from the high ground), of course, more of a problem.
More than experience, luck’s got to be on your side too. Very sad.
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I don't get it. You don't think he's wrong do you?
WHY IS MOIST AIR LESS DENSE THAN DRY AIR AT SAME TEMPERATURE
WHY IS MOIST AIR LESS DENSE THAN DRY AIR AT SAME TEMPERATURE
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Would some weather smarty pants please clear up the issue of whether fog increases or decreases air density and also wing performance please.
Last edited by piperboy84; 27th Jan 2017 at 18:00.
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Piperboy, I think someone just did. (See Holy Moley, above.)
As to wing performance, I'm not sure what performance parameters you have in mind. You may need the help of an aerodynamicist; I would guess, if asked to, that if every variable apart from air density is held constant, the greater the density the greater the lift generated by a wing would be, but what do I know.
I started to list all the other variables that need to be constant; AoA, airspeed, temperature, etc etc, but gave up.
Do gliders have a lower rate of descent in dry, therefore denser air? I think Council Van is saying they do, unless he's talking only about engine thrust in powered aircraft. I wouldn't know; the only gliders I've flown (T21, Swallow, ancient Blanik L-13) went downhill fast in any conditions......
As to wing performance, I'm not sure what performance parameters you have in mind. You may need the help of an aerodynamicist; I would guess, if asked to, that if every variable apart from air density is held constant, the greater the density the greater the lift generated by a wing would be, but what do I know.
I started to list all the other variables that need to be constant; AoA, airspeed, temperature, etc etc, but gave up.
Do gliders have a lower rate of descent in dry, therefore denser air? I think Council Van is saying they do, unless he's talking only about engine thrust in powered aircraft. I wouldn't know; the only gliders I've flown (T21, Swallow, ancient Blanik L-13) went downhill fast in any conditions......
Last edited by Capot; 27th Jan 2017 at 18:34.
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Any one have a degree in aerodynamics?
In a glider,
Moist air, less dense=less drag, less dense=less lift. Which has the biggest effect? I would guess the reduction in lift generated would be greater than the reduction in drag leading to an increase in rate of decent.
However it is 20 years since I did my ATPL written exams, 30 years since I studied A level physics and I do not have a degree in aerodynamics.
Interesting but the effect of moisture content of air on lift/drag is probably irrelevant in this unfortunate incident.
In a glider,
Moist air, less dense=less drag, less dense=less lift. Which has the biggest effect? I would guess the reduction in lift generated would be greater than the reduction in drag leading to an increase in rate of decent.
However it is 20 years since I did my ATPL written exams, 30 years since I studied A level physics and I do not have a degree in aerodynamics.
Interesting but the effect of moisture content of air on lift/drag is probably irrelevant in this unfortunate incident.
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What may be relevant is that the low air density due to the high humidity in foggy conditions would reduce both engine power and rate of climb. In the event of an engine failure, A PA30 pilot might have found himself in trouble.
Being the close friend of a relative of the deceased, I am not inclined to speculate on the cause of the accident and have no axe to grind. The pilot and aircraft were competent in the weather conditions prevailing at that time.
Being the close friend of a relative of the deceased, I am not inclined to speculate on the cause of the accident and have no axe to grind. The pilot and aircraft were competent in the weather conditions prevailing at that time.
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This piece of technical analysis seems to have brought forth a fountain of wisdom on meteorology. I`d rather thought of it more in the lines of Baldrick`s contribution to the discussion on the causes of the First World War. If I may rephrase it, it may also read : When its foggy, the air is thin and the engine does not get enough air to produce sufficient power to make the plane climb fast enough, so it crashes. I have for my sins flown light twins in fog. Had I known about this I would have used a hot air balloon instead.
I find it difficult to believe that humidity had any part to play in the performance of the aircraft (carb ice and airframe/induction icing notwithstanding).
The difference in density between dry and saturated air is negligible at the temperatures pertaining for this accident. A measurable difference first occurs at about 25C. At 50C the difference in density is about 5%. At 65C it is about 10%.
For a good diagram and explanation, visit:
Density of Moist Humid Air
The difference in density between dry and saturated air is negligible at the temperatures pertaining for this accident. A measurable difference first occurs at about 25C. At 50C the difference in density is about 5%. At 65C it is about 10%.
For a good diagram and explanation, visit:
Density of Moist Humid Air
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As someone who doesn't have a degree in meteorology and who passed his met exams over forty years ago, I can say from experience, foggy days did affect lift adversely. It was counter intuitive for me but I couldn't argue with the affected handling. I didn't like flying in cloud either. It may have been psychological.
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This topic has now drifted from an a/c crash to a met' lesson. Was the a/c SE? Let's wait & see after AAIB have had their say. Met' lessons elsewhere??
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So if I'm reading this right, saturated air causing visible moisture (fog) has less density than non saturated but at the lower temperatures needed to create fog (100% saturation) the density becomes a lot less relevant?
Last edited by piperboy84; 27th Jan 2017 at 20:15.
I find it difficult to believe that humidity had any part to play in the performance of the aircraft (carb ice and airframe/induction icing notwithstanding).
The difference in density between dry and saturated air is negligible at the temperatures pertaining for this accident. A measurable difference first occurs at about 25C. At 50C the difference in density is about 5%. At 65C it is about 10%.
The difference in density between dry and saturated air is negligible at the temperatures pertaining for this accident. A measurable difference first occurs at about 25C. At 50C the difference in density is about 5%. At 65C it is about 10%.
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Dave Norris 1952 – 2017
As many will be aware by now, long time member of the VAC Dave Norris was tragically killed in a flying accident in Oxfordshire on 15 January 2017
There will be a Memorial Service for Dave in his home village at St Faith Church, St Faith's Close, Newton Longville, Buckinghamshire, MK17 0AL at 13:00 on 10th February which VAC members may attend.
The service will be followed later in the afternoon by a private cremation.
To extend our condolences to his wife and family for their loss, the Vintage Aircraft Club will be sending a floral tribute on behalf of the Membership.
Peter Wright (VAC Chairman
As many will be aware by now, long time member of the VAC Dave Norris was tragically killed in a flying accident in Oxfordshire on 15 January 2017
There will be a Memorial Service for Dave in his home village at St Faith Church, St Faith's Close, Newton Longville, Buckinghamshire, MK17 0AL at 13:00 on 10th February which VAC members may attend.
The service will be followed later in the afternoon by a private cremation.
To extend our condolences to his wife and family for their loss, the Vintage Aircraft Club will be sending a floral tribute on behalf of the Membership.
Peter Wright (VAC Chairman
