Cocpit design requirements
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Er, not that I'm aware of. Care to expand?
I do understand your position, but we are encouraged to look ahead and not simply do what has been done before - anyone can copy - just to get an aircraft certified.
If we cannot dream a little, come up with new ideas and then analyse them drawing a conslusion based on solid research and engineering then we aren't really 'masters' of our science, and have fallen short of earning an MSc.
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Do a Hover - it avoids G
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glum
You might like to move the tailplane down the fin a tad so that you can put it at the large LE up angle that will be needed during some stages of the transition.
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Really?
I know very little about structural design, aerodynamic loading and the like but I will pass on your observation to the professor who drew the concept!
I know very little about structural design, aerodynamic loading and the like but I will pass on your observation to the professor who drew the concept!
I'd also check the calculations on your tailplane volume coefficient - looks visually quite low to me, which could give you longitudinal stability and control problems: solveable technically with FBW, but there's really no reason to. In this application you are better of with something that has reasonable natural stability - you've no real need for combat level standards in manoeuverability.
Darrol Stinton's books "Design of the Aeroplane" and "Flying Qualities and Flight Testing of the Aeroplane" will lead you easily through the calcs.
G
Darrol Stinton's books "Design of the Aeroplane" and "Flying Qualities and Flight Testing of the Aeroplane" will lead you easily through the calcs.
G
Do a Hover - it avoids G
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glum
It is not about any of the topics you mention.
It is just about thinking how the rotor slipstream will blow over the tailplane at intermediate nacelle angles and how its angle to the fuselage datum will have to be adjusted to keep its angle of attack within a sensible range. Call it aeronautical common sense if you will.
Or you could just look at any tilt wing or tilt rotor aircraft that has flown in the past or is flying today and observe where their horizontal tail is in mid transition.
It even applies to helicopters that use a horizontal tail.
As to passing on my comment to your Professor I would bet money he can't understand why nobody in your team has yet pointed out his deliberate mistake.
He is trying to get you to think!
It is just about thinking how the rotor slipstream will blow over the tailplane at intermediate nacelle angles and how its angle to the fuselage datum will have to be adjusted to keep its angle of attack within a sensible range. Call it aeronautical common sense if you will.
Or you could just look at any tilt wing or tilt rotor aircraft that has flown in the past or is flying today and observe where their horizontal tail is in mid transition.
It even applies to helicopters that use a horizontal tail.
As to passing on my comment to your Professor I would bet money he can't understand why nobody in your team has yet pointed out his deliberate mistake.
He is trying to get you to think!
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Glum,
There's a picture of the CL-84 here which shows what John's saying. Overall your model looks a lot like a proposed update of the Dynavert in the 1990s that didn't get past the drawing board stage (or the BA609).
There's a picture of the CL-84 here which shows what John's saying. Overall your model looks a lot like a proposed update of the Dynavert in the 1990s that didn't get past the drawing board stage (or the BA609).
Do a Hover - it avoids G
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glum
Good - that is what we like to hear!
There is a great career to be made as a specialist of course and these days many jobs in industry are done by teams of specialists. However one way to make yourself stand out from the other specialists in your area is to have a decent generalist education as well. Cranfield is one of the better places to get that so fill your boots.
In the flight test business teams of specialists can easily run into trouble if an event occurs in the air and the team managing that flight does not include the relevant specialist who can appreciate the implications of the event. This happened to me in the US where they have some of the best specialists in the world but are not so heavy in generalists.
When I asked for the sideslip limits on a .8M point I was doing (after the aircraft started to go very sideways) the test director said there was none and I should press on. I asked him to check with base - same answer. I refused to do any more and landed. As I climbed down the ladder I was met by an RAF Wing Commander UK observer who told me in no uncertain way I could not treat the US folk that way. As a UK alien when I entered the debrief room you could have cut the atmos with a knife. I used a loudspeaking telephone on the table to speak to the structural guy who had designed the back end he told me what the limit was - they checked the aircraft instrumentation and sure enough the point I had stopped at was right on the 80% fin strength line (beyond which you needed to use an instrumented fin)
Of course now the atmos changed totally and the specialists all wanted to know how I realised that we should stop when there was no trials paperwork that said so. I explained I had received a good generalist education in the business of aeroplanes.
Sorry you probably did not want to know all that
There is a great career to be made as a specialist of course and these days many jobs in industry are done by teams of specialists. However one way to make yourself stand out from the other specialists in your area is to have a decent generalist education as well. Cranfield is one of the better places to get that so fill your boots.
In the flight test business teams of specialists can easily run into trouble if an event occurs in the air and the team managing that flight does not include the relevant specialist who can appreciate the implications of the event. This happened to me in the US where they have some of the best specialists in the world but are not so heavy in generalists.
When I asked for the sideslip limits on a .8M point I was doing (after the aircraft started to go very sideways) the test director said there was none and I should press on. I asked him to check with base - same answer. I refused to do any more and landed. As I climbed down the ladder I was met by an RAF Wing Commander UK observer who told me in no uncertain way I could not treat the US folk that way. As a UK alien when I entered the debrief room you could have cut the atmos with a knife. I used a loudspeaking telephone on the table to speak to the structural guy who had designed the back end he told me what the limit was - they checked the aircraft instrumentation and sure enough the point I had stopped at was right on the 80% fin strength line (beyond which you needed to use an instrumented fin)
Of course now the atmos changed totally and the specialists all wanted to know how I realised that we should stop when there was no trials paperwork that said so. I explained I had received a good generalist education in the business of aeroplanes.
Sorry you probably did not want to know all that
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Sorry you probably did not want to know all that
I spoke to the guy who's designing the tail, and apparently the horizontal stab is sufficiently high so as to be clear of prop wash. He does want to increase the size though, as his calculations seem to indicate it is too small in some manouevers...
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glum
If you consider the slipstream to be a tube of fast moving air the diameter of the prop rotors that may be so. Sadly that energetic tube of air will induce flow at say 1.5 or more times the prop diam. Admittedly it will not be as fast as the core flow but it will still represent a huge downwash at the top of that fin and to take the longit control sting out of that you will have to align the tailplane LE up.
The reason helicopters with a small tailplane have to put that at a big LE up angle during transitions is similar (since that the tailplane is not actually under the rotor itself). Air is quite viscous and works to reduce any simple shear between high and low velocities.
BTW I believe that marked shear stresses produce a lot of the noise associated with jet engine exhaust. As a result nozzle design features try to encourage the mixing between the jet and the surrounding air to reduce shear related noise. Here you might like to increase the actual shear and so minimise the effective diam of the rotor's influence but I suspect nobody knows how to do that.
The reason helicopters with a small tailplane have to put that at a big LE up angle during transitions is similar (since that the tailplane is not actually under the rotor itself). Air is quite viscous and works to reduce any simple shear between high and low velocities.
BTW I believe that marked shear stresses produce a lot of the noise associated with jet engine exhaust. As a result nozzle design features try to encourage the mixing between the jet and the surrounding air to reduce shear related noise. Here you might like to increase the actual shear and so minimise the effective diam of the rotor's influence but I suspect nobody knows how to do that.
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HUD = Good, now shut it off!
Concerning the HUD (Heads Up Display)
The display system shall have a means of turning the display completely off without taking your hands off the throttles and/or tiller.
Immediately following a normal evening/night landing the information lit up in the HUD has very little relevance, it’s done the work assigned and played its part, but now it clutters up and competes with the runway, taxiway, and signage lighting on the airport’s surface.
I want to completely clear the display without taking my eyes off where the jet is headed. I don’t want to look down for the “clear” button. It would be a much better design if I could turn it off with a tiller, left horn of the yoke or throttle button.
Northbeach
The display system shall have a means of turning the display completely off without taking your hands off the throttles and/or tiller.
Immediately following a normal evening/night landing the information lit up in the HUD has very little relevance, it’s done the work assigned and played its part, but now it clutters up and competes with the runway, taxiway, and signage lighting on the airport’s surface.
I want to completely clear the display without taking my eyes off where the jet is headed. I don’t want to look down for the “clear” button. It would be a much better design if I could turn it off with a tiller, left horn of the yoke or throttle button.
Northbeach
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Northbeach,
Not sure quite why you'd want to clear the HUD just because you're on the ground. Most current HUDs will provide taxi speed/acceleration/decell cues and runway status (EVS) with future(?) developments such as TNASA to give positive taxi direction.
Glum,
If you consider the deep stall phenomenon on a T-Tail aircraft, I'm not sure there's such a tail geometry that can be outside of the prop wash/wing influence. The caveat being that I've only been forced to work on & program Stall systems for such birds - I'm not a Flight Scientist.
Not sure quite why you'd want to clear the HUD just because you're on the ground. Most current HUDs will provide taxi speed/acceleration/decell cues and runway status (EVS) with future(?) developments such as TNASA to give positive taxi direction.
Glum,
If you consider the deep stall phenomenon on a T-Tail aircraft, I'm not sure there's such a tail geometry that can be outside of the prop wash/wing influence. The caveat being that I've only been forced to work on & program Stall systems for such birds - I'm not a Flight Scientist.
Northbeach,
Perhaps your HUD symbology could be automatically repositioned higher up the glass shortly after weight-on-wheels (ie when the attitude or velocity vector are no longer relevant)? This would avoid interference with airfield lighting. An easily-visible groundspeed readout is very useful during a rolling landing and when taxying at night. The heading tape can also be useful in reduced visibility to confirm you're taking the correct taxyway!
Some HUDs use auto-brightness sensors to adjust the symbology brightness without input from the pilot. My experience of these is somewhat mixed and it can be quite uncomfortable when the symbology incorrectly fades from view at a critical moment! A simple solution is to include a manual HUD brightness control wheel as one of the "HOTAS" switches and this is worth considering. It doesn't have to be in a 'prime' position but it is certainly handy to be able to adjust without removing hands from controls. This would also allow pilots easily to turn the brightness to zero if they didn't want the symbology on the ground.
If your tilt-rotor is to have military application then don't forget to include a countermeasures dispense button somewhere on the stick. Automatic systems are not foolproof yet! A 3-way transmit button (Com 1, Com 2, Simulcast) is useful for military flying as well; the handling pilot may need to communicate on ATC and on a formation frequency in rapid succession.
Perhaps your HUD symbology could be automatically repositioned higher up the glass shortly after weight-on-wheels (ie when the attitude or velocity vector are no longer relevant)? This would avoid interference with airfield lighting. An easily-visible groundspeed readout is very useful during a rolling landing and when taxying at night. The heading tape can also be useful in reduced visibility to confirm you're taking the correct taxyway!
Some HUDs use auto-brightness sensors to adjust the symbology brightness without input from the pilot. My experience of these is somewhat mixed and it can be quite uncomfortable when the symbology incorrectly fades from view at a critical moment! A simple solution is to include a manual HUD brightness control wheel as one of the "HOTAS" switches and this is worth considering. It doesn't have to be in a 'prime' position but it is certainly handy to be able to adjust without removing hands from controls. This would also allow pilots easily to turn the brightness to zero if they didn't want the symbology on the ground.
If your tilt-rotor is to have military application then don't forget to include a countermeasures dispense button somewhere on the stick. Automatic systems are not foolproof yet! A 3-way transmit button (Com 1, Com 2, Simulcast) is useful for military flying as well; the handling pilot may need to communicate on ATC and on a formation frequency in rapid succession.
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More good input gents, thanks.
We're actually going without a HUD since there isn't any spare room on the overhead panel and very little on the coaming / behind the flatscreens to mount it. Perhaps equally importantly, HUD design isn't particularly new and there isn't a huge benefit in learning to design one (or copy someone else's!).
However... We have elected to develop single pilot ops. The cockpit will retain two full sets of displays / controls as it was felt the certification process would be impossible if we chose to go with a single pilot installation.
This throws up some huge challenges, not least what happens when the pilot is incapacitated! The general thrust at this point is to have the aircraft autonomously land at the nearest available airfield, so defining the sequence of events from the take-over (what constitues pilot unable to control?) through declaring an emergency, requesting a new flight plan and then controlling the aircraft all the way to stopping on the ground is bending our brains in whole new ways.
We will also need to automate checklists, provide voice prompts, voice recognition, some decent algorithms and on-screen assistance for system failures.
Part of the process will be writing certification rules to present to the EASA / FAA to demonstrate the problems, and the solutions we have designed to mitigate the risks associated with them.
With firms such as Embraer declaring their intention to work towards SPO within the next 10-15 years, I feel it is high time a University gave this more than a brief consideration.
We're actually going without a HUD since there isn't any spare room on the overhead panel and very little on the coaming / behind the flatscreens to mount it. Perhaps equally importantly, HUD design isn't particularly new and there isn't a huge benefit in learning to design one (or copy someone else's!).
However... We have elected to develop single pilot ops. The cockpit will retain two full sets of displays / controls as it was felt the certification process would be impossible if we chose to go with a single pilot installation.
This throws up some huge challenges, not least what happens when the pilot is incapacitated! The general thrust at this point is to have the aircraft autonomously land at the nearest available airfield, so defining the sequence of events from the take-over (what constitues pilot unable to control?) through declaring an emergency, requesting a new flight plan and then controlling the aircraft all the way to stopping on the ground is bending our brains in whole new ways.
We will also need to automate checklists, provide voice prompts, voice recognition, some decent algorithms and on-screen assistance for system failures.
Part of the process will be writing certification rules to present to the EASA / FAA to demonstrate the problems, and the solutions we have designed to mitigate the risks associated with them.
With firms such as Embraer declaring their intention to work towards SPO within the next 10-15 years, I feel it is high time a University gave this more than a brief consideration.