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Newton's 3rd Law

Transport Innovation (it says)

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Martin Kyte31/10/2020 16:24:52
2114 forum posts
37 photos

In the UK the blower would be pointing backwards and the brolly used to keep the rain off.

regards Martin

Meunier31/10/2020 16:29:37
370 forum posts
5 photos
Posted by Mick B1 on 31/10/2020 15:48:09:
Posted by Meunier on 31/10/2020 15:22:13:
Posted by John Haine on 31/10/2020 08:10:22:

So DC9s have rear jet engines and apply reverse thrust with pivoted scoops that hinge into the jet stream. I've seen them at O'Hare back off the stand using reverse thrust. How does that work?


Edited By John Haine on 31/10/2020 08:15:0

Such manoeuvering procedures mostly banned these days for both rear and wing mounted engines, experience found that engines were being damaged by FOD thrown up by reverser efflux was being ingested into the engine air intakes - cheaper to call for a tug.

Why wouldn't that happen on runway braking? Is it kept cleaner of random debris?

Don't know for sure but think that the aircraft is still travelling forward at a sufficient speed to 'overtake' any FOD thrown up by the reverse thrust, which usually reduces as the aircraft reduces speed.
Is it kept cleaner of random debris ? usually-yes- and subject to regular inspections whereas the parking bays can be grubby/dusty places where people work, not to mention loose baggage containers which could be blown around with reverse thrust

mark costello 131/10/2020 17:59:05
613 forum posts
12 photos

they probably have never lifted the Wife's luggage, could have been used to anchor Noah's Ark.

Henry Artist31/10/2020 19:23:28
99 forum posts
46 photos
Posted by Neil Wyatt on 30/10/2020 17:57:13:
While I am sceptical that he may be benefiting from a slope or other hidden assistance, no it doesn't violate the third law.
The intake of air a 'suck' will always be non-directional while the blow is, in this case the brolly is reversing the flow and entraining more air in the process which may increase the efficiency.

I believe Neil's analysis is correct. Exactly the same principle is used when a boat fitted with a kitchen rudder is moving astern.

The kitchen rudder seems to be something of a rarity these days though they can be super useful to the model steam boat fraternity. The engine and propeller only run in one direction thus simplifying construction. To a certain extent speed can also be controlled by the rudder. When steering the boat a kitchen rudder behaves rather like a steerable Kort nozzle.

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