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Robert Atkinson 201/12/2019 20:49:01
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644 forum posts
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We used to hear the tail end of Concords supersonic runs up the bay of Biscay all the way in Christchurch on cool quiet evenings.
And I did of course hear the booms from Thrust SSC back in 1997. The car went supersonic 5 times. One of these was unintentional. The car was to run to a predetermined indicated airspeed which should hav been just below Mach 1, There was however a clear boom. The first suspect was the airspeed indicator calibration (which was my responsibility, I built the speedometer and Mach meter for the car) but it turned out that when calculating the target speed they forgot to allow for the affect of altitude on Mach number. The Black Rock desert is at about 3900ft above sea level.

Robert G8RPI.

Meunier01/12/2019 21:19:24
315 forum posts
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I had to check to see that Martin C did not correspond with Martin Baker

DaveD

and we occasionally get sonic bangs when the boys in blue from Mont-de-Marsan base get it just that bit wrong on low-level sorties..
with many buildings around here roofed with Roman tiles, they do rattle a bit !

Martin Connelly01/12/2019 21:26:27
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I was near an RAF runway when the crew banged out of an F4 as it was landing, I was at Wideawake airfield when an F4 did a flight test after an engine change. We knew there was going to be a sonic bang.

Martin C

Mike Poole01/12/2019 22:09:10
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Living next to Martin Bakers test facility at Chalgrove we hear quite a lot of test ejections from the Meteors they use for testing, I have not felt that they sounded like a sonic boom but I lived a few hundred meters from the ejection point the sonic booms were rather more distant and the culprits were possibly from the Clutch stations of Wildenrath, Brüggen, Gutersloh etc. Or maybe the Luftwaffe with their widowmaker Starfighters, who knows it was a long time ago.

Mike

martin perman01/12/2019 22:50:52
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A slight aside, I was sent to Martin Baker's site on the Isle of Man to service some machine tools many moons ago, I had never been before and when I walked out of the Airport building I got into a cab and said the Martin Baker Factory please, he drove 50yds and did a 180 deg turn and 50 yds again on the other side of the carriageway stopped and said there you are sir no charge. Silly me.

Martin P

Neil Wyatt01/12/2019 23:52:08
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Heard my first sonic booms when Concorde first started - it used to go supersonic over the Bristol Channel, I was most disappointed when then made it wait until it was over open sea.

Short Skyvan was among my favourite Airfix kits.

Neil

Robert Atkinson 202/12/2019 19:28:52
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644 forum posts
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Thrust SSC had a Martin Baker ejection seat rocket motor mounted "upside" down in the nose. The intention was that if the nose started to lift it would fire keeping it on the ground long enough for the hydraulic ride height control to jack the rear end up and generate aerodynamic downforce and drag. The test firing was pretty impressivebut diddn't sound like a sonic boom. The main seat "gun" cartridges might sound a bit like it though. I've worked on a Skyvan (a 3A) and several 330's and 360's It's no coincidence that Shorts were asked to build the Miles Aerovan a couple of years before staring work on the Skyvan. It's was more a case of what not to do rather than copying it.

Robert G8RPI.

Martin Connelly03/12/2019 21:50:48
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On the F4 as well as the initial main gun cartridge there is a second cartridge that is triggered after the seat has travelled half way out of the cockpit. The idea was to keep g forces below a dangerous level by not putting out the full force needed for ejection in one go.These two cartridges put enough pressure into the seat tube to push the seat and crew member out of the cockpit at a high G force so is not just a few psi. Once the seat has risen far enough the tube that is part of the aircraft and the seat part company and this pressure is released with a sound like a piece of artillery being fired. If you look at pictures of aircraft where the seat has been used you can see the tube protruding from the cockpit. The rocket only fired after the seat had left the cockpit.

Martin C

Michael Gilligan21/01/2020 10:54:57
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15704 forum posts
687 photos

This is interesting [and I think legitimately falls within the thread title] : **LINK**

https://robotics.sciencemag.org/content/5/38/eaay1246

Download the full paper via that page.

MichaelG.

Andrew Johnston13/03/2020 20:44:06
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5499 forum posts
647 photos

Nipped out into the garden this afternoon to do a bit of digging between trying to sort out my mum's car with the garage and getting a quote to vulcanise tyres on my traction engine wheels. Not sure which was the most painful! I'd only been out a few minutes when a Spitfire flew over at less than a 1000ft on the way to Duxford. Certainly shifting, I hope he was below 250kts. Later model with pointy wingtips and the engine sounding like it had something loose, so a Griffon.

Andrew

Jon Lawes13/03/2020 21:25:44
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371 forum posts

My late grandfather always claimed he first heard a sonic boom in the 1940s. When pressed he would admit it was the blade tips of the Harvard.

martin perman13/03/2020 21:59:04
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1828 forum posts
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I took a ride up the A1 to Newark Aircraft Museum on Wednesday, I'd never been there before and was most impressed with the exhibits, their theme seems to be late forties and fifties exhibits with a few sixties as well, I took 106 pictures so must have been good.

Martin P

Cornish Jack13/03/2020 23:34:23
1121 forum posts
159 photos

Witnessed 2 and a 'half' bang seat events when I was S&R instructing at Valley - all from Gnats. The 2 were 'Bloggs' and his instructor when the pitch control jammed. Their departure straightened up the trim and the Gnat continued circling on its own and descending slowly to end up close to a batch of holidaymaker swimmers ... no one hurt!

The 'half' was the climax of a three ship formation take-off when No. 3 selected gear up too soon. He went back onto the runway sans gear and skidding on the slipper tanks. They caught fire and produced a travelling fireball about 20-30 yards behind him. He eventually came to a stop on the peri track just behind a queue of traffic waiting to cross the runway threshold. Bloggs was out and running just ahead of the fireball. Gnat bang seats were pneumatic in operation and after the fire had cooked the firing tube for a minute or so, the tube worked! Our resident Whirlwind had rushed to the spot to see if they could help and the departing seat missed their rotor by 'not a lot'!! We later heard that the head of the traffic queue was a a fuel bowser and,. seeing the Gnat plus fire ball heading towards him, he stripped every gear in the box trying to get moving!! Valley had its 'interesting' moments1

rgds

Bill

Mike Poole13/03/2020 23:44:45
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2575 forum posts
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What is S&R Bill

Mike

Search and Rescue, just worked it outsmiley
 

Edited By Mike Poole on 13/03/2020 23:46:20

not done it yet14/03/2020 00:01:49
4639 forum posts
16 photos

We were treated to a talk by Flight Lieutenant Charlie Brown BSc (RAFR) last night. He provided us with quite a lot of his experience re driving these old fighter aircraft. Seems like the spitfire was difficult on the ground but marvellous once airborne. I didn’t realise that so many ME109s were lost on either take off or landing (not under fire).

He also compared the spitfire to the ‘dolly’ as I think he called it. One can understand the reasons why the Hurricanes were sent to attack the bombers while the spitfires kept the german air cover busy!

Why ‘not exceeding 250kts’, Andrew? The griffon versions could easily go much faster than that?

Ron Laden14/03/2020 04:37:04
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1920 forum posts
367 photos

250 kts is the speed limit below 10,000 feet that's why.

Andrew Johnston14/03/2020 11:13:17
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5499 forum posts
647 photos

Ron is correct, with one minor bit of pedantry, the limit is below FL100, not quite the same as 10000ft. smile

Andrew

David T31/03/2020 14:09:35
74 forum posts
14 photos

Did I just see an RAF Globemaster go into Southend airport??

 

Shortly followed by a second one

Edited By David T on 31/03/2020 14:32:21

martin perman31/03/2020 17:25:31
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1828 forum posts
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Posted by David T on 31/03/2020 14:09:35:

Did I just see an RAF Globemaster go into Southend airport??

Shortly followed by a second one

Edited By David T on 31/03/2020 14:32:21

Did they look like these **LINK**

Martin P

Jon Lawes31/03/2020 19:16:06
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371 forum posts

I wonder if thats the same Charlie Brown I knew from ETPS? I suspect there are many "Charlie" Browns! This one was primarily Rotary wing I think, he was CO at the time.

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