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-   -   Harrier OCU film (https://www.pprune.org/military-aviation/636292-harrier-ocu-film.html)

Easy Street 24th Oct 2020 11:08


Originally Posted by tartare (Post 10910536)
Was thrust split between the main nozzles fore and aft to control pitch in hover and low speed flight, as well as the puffers in the nose and tail?
How was that done, given front nozzles were cold and back nozzles were hot?

No, the thrust split between the front and rear nozzles couldn’t be adjusted so all jetborne pitch control was on the puffers. The rear nozzles generated more thrust due to their higher exhaust velocity; this was dealt with by positioning the rear nozzles slightly closer behind the CofG than the front nozzles were in front of it so the moment arms balanced.

Differential nozzle control for roll and pitch was proposed at one point by a certain John Farley, as he recounts among other fascinating insights from page 120 onwards at this link. Most interestingly in the context of this thread, he talks about the perceived ‘heresy’ of his aim to simplify the STOVL control system and the scepticism he faced both from the Hawker design office and from pilots who considered mastery of the nozzle control lever to be a marker of their elite status. He says the advantage of the VAAC testbed being a 2-seater was that test pilots with no Harrier background could fly and assess the control system with no such prejudice. Brilliant engineering that played a large part in establishing the UK’s early privileges in the JSF programme - and here we are in 2020 with F-35B STOVL such a walk in the park that no 2-seater is needed.

Nige321 24th Oct 2020 12:57


Originally Posted by Easy Street (Post 10910781)
No, the thrust split between the front and rear nozzles couldn’t be adjusted so all jetborne pitch control was on the puffers. The rear nozzles generated more thrust due to their higher exhaust velocity; this was dealt with by positioning the rear nozzles slightly closer behind the CofG than the front nozzles were in front of it so the moment arms balanced.

Differential nozzle control for roll and pitch was proposed at one point by a certain John Farley, as he recounts among other fascinating insights from page 120 onwards at this link. Most interestingly in the context of this thread, he talks about the perceived ‘heresy’ of his aim to simplify the STOVL control system and the scepticism he faced both from the Hawker design office and from pilots who considered mastery of the nozzle control lever to be a marker of their elite status. He says the advantage of the VAAC testbed being a 2-seater was that test pilots with no Harrier background could fly and assess the control system with no such prejudice. Brilliant engineering that played a large part in establishing the UK’s early privileges in the JSF programme - and here we are in 2020 with F-35B STOVL such a walk in the park that no 2-seater is needed.

Your link is broken...


spekesoftly 24th Oct 2020 13:05

The link works for me, but the pdf file takes a short while to load.

Nige321 24th Oct 2020 13:24


Originally Posted by spekesoftly (Post 10910858)
The link works for me, but the pdf file takes a short while to load.

Yes, disregard last, it dumps a pdf in the downloads...!

lsh 24th Oct 2020 15:00


Originally Posted by charliegolf (Post 10910772)
I thought he had departed the fix? He certainly is/was everything you say about him. Never mentioned Harriers. Unless you nagged him! When you did, you got the clearest explanation you could want.

CG

Pleased to say he checked in on facebook for his birthday a couple of days back!
The virtues of a glass of red!
So many stories of flying with him.............all good!

lsh
:E

charliegolf 24th Oct 2020 15:08


Originally Posted by lsh (Post 10910907)
Pleased to say he checked in on facebook for his birthday a couple of days back!
The virtues of a glass of red!
So many stories of flying with him.............all good!

lsh
:E

Excellent news!

CG


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