Ack. I'd like to say "I'm back! =D" but it seems every post I make involves saying that in some form or another I might as well admit that I'm just slow to check online.
The reason? Uni's been kicking me in the teeth. But fear not, I actually have things to show for it that are (mostly) relevant to this forum. So, while I can't show everything yet until IP rights are cleared up I can at least make a start with what I've been up to.
Some of you know my chosen subject at uni is aeronautics, and as a final year student I have to carry out an individual project indicative of my learning and skills gained from the last 3 years of study. Normally it's research based or the optimization/re-design of a specific component, such as canopy seals to reduce air drag and so forth. I, like a fool, decided to design a wing for a theoretical training jet plane. That was foolish because I also decided that it had to make use of a dynamic property known as Vortex Lift. What was even more foolish was that I soon realized that in order to prove the wing is fit for purpose, I needed to factor in the plane's tails, weight, intakes and stability...so I ended up designing the whole damn plane.
Truespace 6 was actually used quite extensively so it's nice to know the program can still do its stuff. I'll also be showing some of the work done in two other modelling packages, Alias Automotive and PTC Creo, dedicated surface and solid modelling programs, as well as an aerodynamic analysis package called Ansys Fluent.
Cheer up U3DA. At least I'm modelling a plane I designed myself for once!
Trainer Jet WIP
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Trainer Jet WIP
Last edited by Steve on 29 Apr 2013, 21:29, edited 2 times in total.
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Re: Trainer Jet WIP
Okay. So a bit about the plane itself.
Many ex-military jet trainer aircraft, like the Jet Provost or L-39 have been converted to civilian General Aviation use, but as these jets continue to age the running costs will mount exponentially and repairs will become much more difficult. The problem is that aircraft currently in use by the military may not be operable under General Aviation rules, leaving a massive hole in the market. So there's potential to introduce a new aircraft which matches the aerodynamic performance of existing jets in military operation. but because it's new and specifically designed, will be of a fraction of the cost it takes to run the current war-bird fleets. It starts to get tricky because civvies don't always use big long runways, so the aircraft must be short and unprepared field capable, but to match the performance of and must be post-stall maneuverable. But also modern fighters are maneuverable because they are unstable, which requires flight computers to adjust the aircraft every micro-second as humans can't manage it. Civvies don't have that luxury either.
So, the target specs for the aircraft are worked out as:
----------------------------------------------------------------------
Type: Civilian Fast Jet Trainer
Certification: Aerobatic, IFR (night, crap weather) capable
Crew: 2 – (1 pilot, 1 Passenger/Student)
MTOW: 5,670kg or less
Payload: 600kg capacity external stores
VSO: 80kts @ Max weight (92mph)
VMax: Mach 0.6-0.8 (456mph-609mph)
Take-off distance: 300m @ Max weight
Landing distance: 250m @ Max weight
G load limit: +8g/-3g
Rate of climb: 3150ft/min
Maximum Height: 30,000ft (9144m)
Range: 8,600km
Loiter time: 30 minutes @ max range
----------------------------------------------------------------------
TL;DR version. Making a jet Trainer that civvies can use. has to be ^^^^ that good
So to work out where I'm going to put the wing, I needed to come up with a basic fuselage design. Here it is:
To highlight all the funny errors, this was the quickly made in Truespace
More to come a bit later
Many ex-military jet trainer aircraft, like the Jet Provost or L-39 have been converted to civilian General Aviation use, but as these jets continue to age the running costs will mount exponentially and repairs will become much more difficult. The problem is that aircraft currently in use by the military may not be operable under General Aviation rules, leaving a massive hole in the market. So there's potential to introduce a new aircraft which matches the aerodynamic performance of existing jets in military operation. but because it's new and specifically designed, will be of a fraction of the cost it takes to run the current war-bird fleets. It starts to get tricky because civvies don't always use big long runways, so the aircraft must be short and unprepared field capable, but to match the performance of and must be post-stall maneuverable. But also modern fighters are maneuverable because they are unstable, which requires flight computers to adjust the aircraft every micro-second as humans can't manage it. Civvies don't have that luxury either.
So, the target specs for the aircraft are worked out as:
----------------------------------------------------------------------
Type: Civilian Fast Jet Trainer
Certification: Aerobatic, IFR (night, crap weather) capable
Crew: 2 – (1 pilot, 1 Passenger/Student)
MTOW: 5,670kg or less
Payload: 600kg capacity external stores
VSO: 80kts @ Max weight (92mph)
VMax: Mach 0.6-0.8 (456mph-609mph)
Take-off distance: 300m @ Max weight
Landing distance: 250m @ Max weight
G load limit: +8g/-3g
Rate of climb: 3150ft/min
Maximum Height: 30,000ft (9144m)
Range: 8,600km
Loiter time: 30 minutes @ max range
----------------------------------------------------------------------
TL;DR version. Making a jet Trainer that civvies can use. has to be ^^^^ that good
So to work out where I'm going to put the wing, I needed to come up with a basic fuselage design. Here it is:
To highlight all the funny errors, this was the quickly made in Truespace
More to come a bit later
Last edited by Steve on 04 May 2013, 15:00, edited 1 time in total.
-
Unavailableartist
- Petty Officer First Class
- Posts: 58
- Joined: 31 Mar 2013, 19:50
- Type the number ten into the box: 10
Re: Trainer Jet WIP
Looks nice man, I like military-looking (I know this is a civi) jets, can't wait to c it finished.
-
jamesmc
- Captain
- Posts: 1776
- Joined: 08 Jul 2009, 15:35
Re: Trainer Jet WIP
Very smooth and looks mean all at once!
Looking forward to seeing more...
Looking forward to seeing more...
Walk by faith, not by sight.
-
MikomDude
- Captain
- Posts: 1930
- Joined: 04 Oct 2010, 11:12
- Type the number ten into the box: 0
- Location: The Hague, Netherlands
Re: Trainer Jet WIP
Looking cool!
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Re: Trainer Jet WIP
well thank you very much. Slightly ashamed of that model as I've got the final design here and I assure you it looks a lot better than that.
TL;DR version much further below
So, the first thing I need to do, is calculate just how big the wing needs to be, this will be achieved as a function of 'Wing loading' (W/S), or how many kg of aircraft weight per meter of wing area and 'Thrust to weight' (T/W), the ratio of thrust available versus the weight of the aircraft, if T/W=1 then all of the weight can be supported by the engines, enabling sustained vertical flight. The required T/W and W/S values are calculated for takeoff performance, climb performance, stall speed performance and maximum height
We start as we mean to go on...here's how to work each out
...Which was pleasant. It's then all plotted onto a line graph to show the optimum W/S & T/W which satisfies all performance criteria with minimum excess power or wing area. Which was in this case at maximum takeoff weight:
T/W = 0.64
W/S = 272kg/m^2
The wing size can be calculated by dividing weight by the wing loading, so the wing = 19.5m^2
This allows me to pick good aerofoils to generate the most lift for minimum drag. here's the one for the wing root and here's the one for the wingtip
Taking off my anorak now, TL/DR version is. Calculated the wing size, here's a mockup of how big and the shape of how I expect it to look
Leaving the wing 'planform' shape for now though, as the next step is to decide what landing flaps will be used as they need to be specially designed and tested for each aerofoil type.
TL;DR version much further below
So, the first thing I need to do, is calculate just how big the wing needs to be, this will be achieved as a function of 'Wing loading' (W/S), or how many kg of aircraft weight per meter of wing area and 'Thrust to weight' (T/W), the ratio of thrust available versus the weight of the aircraft, if T/W=1 then all of the weight can be supported by the engines, enabling sustained vertical flight. The required T/W and W/S values are calculated for takeoff performance, climb performance, stall speed performance and maximum height
We start as we mean to go on...here's how to work each out
...Which was pleasant. It's then all plotted onto a line graph to show the optimum W/S & T/W which satisfies all performance criteria with minimum excess power or wing area. Which was in this case at maximum takeoff weight:
T/W = 0.64
W/S = 272kg/m^2
The wing size can be calculated by dividing weight by the wing loading, so the wing = 19.5m^2
This allows me to pick good aerofoils to generate the most lift for minimum drag. here's the one for the wing root and here's the one for the wingtip
Taking off my anorak now, TL/DR version is. Calculated the wing size, here's a mockup of how big and the shape of how I expect it to look
Leaving the wing 'planform' shape for now though, as the next step is to decide what landing flaps will be used as they need to be specially designed and tested for each aerofoil type.
-
jamesmc
- Captain
- Posts: 1776
- Joined: 08 Jul 2009, 15:35
Re: Trainer Jet WIP
Looking good!
But, all that math made my head hurt.
But, all that math made my head hurt.
Walk by faith, not by sight.
-
clintonman
- Captain
- Posts: 5659
- Joined: 21 May 2009, 21:08
- Type the number ten into the box: 0
- Location: California
Re: Trainer Jet WIP
Do you plan to produce it in some physical form when you're done? Like a wind tunnel model or a 3D print?
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Re: Trainer Jet WIP
Hi Clintonman.
It's going to be 3D printed, but for display purposes only. There are two things stopping wind tunnel testing at the moment, the first one is skin roughness, which affects the shape more and more as it gets smaller, but the second is 'Reynolds number matching', the wind tunnel at the uni isn't fast enough even for the low speed tests I would like to do.
But, stay tuned, I have done other tests which I'll be showing a little later on which give me a good indication of what the plane is doing.
For those interested. Scale wind tunnel models are used for practical reasons like cost and equipment size. But a scale model isn't tested at the same airspeed as the full size object, as the flow properties of a shape is determined by how turbulent the air is, not the speed at which it is traveling. A 'Reynolds number' indicates how turbulent the flow is, below 2500 it is 'laminar' (smooth), between 2500-5000 it is transitioning to turbulent, and above 5000 is turbulent. To put it into perspective, it is fairly common to see Reynolds numbers on aircraft up to about 1,000,000 at their lowest speeds.
The factors that affect turbulence are the 'Dynamic Viscosity' (how thick and gloopy it acts when it's in motion, which varies from sea level to altitude), the airspeed and the object length. If the object length decreases, so does the turbulence. So opposite to common sense, to balance the correct reynolds number for a scale model, it needs to be tested at a higher airspeed than the full size object.
Also, James, I share your pain. My head hurt too!
It's going to be 3D printed, but for display purposes only. There are two things stopping wind tunnel testing at the moment, the first one is skin roughness, which affects the shape more and more as it gets smaller, but the second is 'Reynolds number matching', the wind tunnel at the uni isn't fast enough even for the low speed tests I would like to do.
But, stay tuned, I have done other tests which I'll be showing a little later on which give me a good indication of what the plane is doing.
For those interested. Scale wind tunnel models are used for practical reasons like cost and equipment size. But a scale model isn't tested at the same airspeed as the full size object, as the flow properties of a shape is determined by how turbulent the air is, not the speed at which it is traveling. A 'Reynolds number' indicates how turbulent the flow is, below 2500 it is 'laminar' (smooth), between 2500-5000 it is transitioning to turbulent, and above 5000 is turbulent. To put it into perspective, it is fairly common to see Reynolds numbers on aircraft up to about 1,000,000 at their lowest speeds.
The factors that affect turbulence are the 'Dynamic Viscosity' (how thick and gloopy it acts when it's in motion, which varies from sea level to altitude), the airspeed and the object length. If the object length decreases, so does the turbulence. So opposite to common sense, to balance the correct reynolds number for a scale model, it needs to be tested at a higher airspeed than the full size object.
Also, James, I share your pain. My head hurt too!
-
Unavailableartist
- Petty Officer First Class
- Posts: 58
- Joined: 31 Mar 2013, 19:50
- Type the number ten into the box: 10
Re: Trainer Jet WIP
As someone who speaks with some experience. Math like that isn't easy... When your in a field like that... It's never easy. It's like the equivalent of back-breaking labor, but only for brains.
Brain-busting.
This may make me switch my engineering major.
Great-Job with the plane... It looks gorgeous.
Brain-busting.
This may make me switch my engineering major.
Great-Job with the plane... It looks gorgeous.
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Re: Trainer Jet WIP
Do it! You'll love it
So, moving swiftly onwards and upwards from that. A quick amount of research and testing suggested that the plane will be a 'mid-wing' configuration and not high or low because it carries many more aerodynamic advantages.
So we're now moving on to aerofoils.
So, the aerofoil is what gives the plane lift. It, like every other component is selected out of compromise based on certain factors, and a lot of the time it's not which shape generates the most lift. It can be the most benign stall conditions, the best lift-drag ratio, thickness for internal storage and so on. But all are selected because it generates the correct amount of lift at minimum drag when the aircraft is in cruise.
Here's the ones I have selected, known as NACA 6 digit aerofoils. The aerofoil needed a lift coefficient of 0.31, therefore I have selected NACA 641,412 as it generates a good amount of lift for minimum drag at the required coefficient. But, this may be too thick an aerofoil to carry over the entire length of the wing, so I have selected a slightly thinner aerofoil, 64A410 to be used at the wingtips, providing minimal drag for maximum lift across the largest speed range possible.
Wing Root. 641-412
Wingtip. 64A410
I've also needed to decide what type of high lift device is needed. For that I've picked out a leading edge slat, which delays stalling effects over the wing by providing fast moving air over the top surface through a slot. And a slotted flap, which provides a greater down wash, larger wing area and a higher angle of attack. The flap itself has its own leading edge slat to make sure it doesn't stall too soon.
The anatomy of the devices looks like this:
You can see the small 'slot' in front of the main flap, called the vane and how in theory it will re-accelerate air through the gap between it and the main flap
This has required a new program, called 'Ansys Fluent', to check the aerodynamics of the aerofoil. I include this because later on it ties in with 3D modelling. Here's some of the results.
Where this sequence of images show the stalling properties of the wing with the flaps down at increasing angle of attack, 10-14 degrees. The colour plots show the amount of turbulence indicating stalled flow.
These are unusual results; a stall develops over the rear section of the wing and is transitioned into strong wake turbulence at a higher angle of attack only to then re-develop. While there is a possibility of simulation error a likely cause could be the effectiveness of the flap vane at varying angles of attack, which is a significantly negative, delaying the effects of a stall. As a result with increasing wing angle of attack the vane will become more effective at providing clean air through the slot gap. This is shown in area A, where separation and turbulence originates from the main wing elements, but pushed away from the flaps where the slot gaps are positioned. While this may indicate that the maximum angle of attack possible is 13 degrees, it may still be firmly in a stalled condition. Pressure plots varying from 9 degrees upwards to 13 appear to confirm that in fact 11 degrees is the maximum usable angle of attack.
And some steamlines showing flow direction around the leading edge slat. If you look you can see a lot of circulation inside the slot gap until the aerofoil reaches a certain angle of attack. That's not good, requiring a redesign
Next up. The wing shape, and some...actually interesting looking simulations
So, moving swiftly onwards and upwards from that. A quick amount of research and testing suggested that the plane will be a 'mid-wing' configuration and not high or low because it carries many more aerodynamic advantages.
So we're now moving on to aerofoils.
So, the aerofoil is what gives the plane lift. It, like every other component is selected out of compromise based on certain factors, and a lot of the time it's not which shape generates the most lift. It can be the most benign stall conditions, the best lift-drag ratio, thickness for internal storage and so on. But all are selected because it generates the correct amount of lift at minimum drag when the aircraft is in cruise.
Here's the ones I have selected, known as NACA 6 digit aerofoils. The aerofoil needed a lift coefficient of 0.31, therefore I have selected NACA 641,412 as it generates a good amount of lift for minimum drag at the required coefficient. But, this may be too thick an aerofoil to carry over the entire length of the wing, so I have selected a slightly thinner aerofoil, 64A410 to be used at the wingtips, providing minimal drag for maximum lift across the largest speed range possible.
Wing Root. 641-412
Wingtip. 64A410
I've also needed to decide what type of high lift device is needed. For that I've picked out a leading edge slat, which delays stalling effects over the wing by providing fast moving air over the top surface through a slot. And a slotted flap, which provides a greater down wash, larger wing area and a higher angle of attack. The flap itself has its own leading edge slat to make sure it doesn't stall too soon.
The anatomy of the devices looks like this:
You can see the small 'slot' in front of the main flap, called the vane and how in theory it will re-accelerate air through the gap between it and the main flap
This has required a new program, called 'Ansys Fluent', to check the aerodynamics of the aerofoil. I include this because later on it ties in with 3D modelling. Here's some of the results.
Where this sequence of images show the stalling properties of the wing with the flaps down at increasing angle of attack, 10-14 degrees. The colour plots show the amount of turbulence indicating stalled flow.
These are unusual results; a stall develops over the rear section of the wing and is transitioned into strong wake turbulence at a higher angle of attack only to then re-develop. While there is a possibility of simulation error a likely cause could be the effectiveness of the flap vane at varying angles of attack, which is a significantly negative, delaying the effects of a stall. As a result with increasing wing angle of attack the vane will become more effective at providing clean air through the slot gap. This is shown in area A, where separation and turbulence originates from the main wing elements, but pushed away from the flaps where the slot gaps are positioned. While this may indicate that the maximum angle of attack possible is 13 degrees, it may still be firmly in a stalled condition. Pressure plots varying from 9 degrees upwards to 13 appear to confirm that in fact 11 degrees is the maximum usable angle of attack.
And some steamlines showing flow direction around the leading edge slat. If you look you can see a lot of circulation inside the slot gap until the aerofoil reaches a certain angle of attack. That's not good, requiring a redesign
Next up. The wing shape, and some...actually interesting looking simulations
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Re: Trainer Jet WIP
One more slightly boring bit to go. What comes next is known as the 'reference planform'. Which is what the wing would be shaped like if it was a straight edged trapezoid extending all the way to the centre of the aircraft.
Now. The wing has the shape it does for a few reasons, but the primary reasons are maximum lift, minimum drag, good stability and controllability but also stall quality. The wing gets thinner (tapers) towards the tip to improve the roll rate as more of the mass closer to the centre, and it reduces weight as less strengthening is needed further out. But it also rakes backwards (known as wing sweep), this is a stability thing, where sweep increases stability both in pitch, yaw and to a slightly lesser extent roll. It also allows aircraft to cruise at a higher mach number before supersonic effects take over.
So the reference planform I chose is here, The flaps cover 60% of the span, with the leading edge slats outboard of that, shown at a suitably high angle of attack to see how it goes. The wing was modelled in 'Alias Automotive'...which was just so fun
Next up is actually properly integrating that with the fuselage. The IP rights are now mine again so I am free to show off the actual design now
Stay tuned
Now. The wing has the shape it does for a few reasons, but the primary reasons are maximum lift, minimum drag, good stability and controllability but also stall quality. The wing gets thinner (tapers) towards the tip to improve the roll rate as more of the mass closer to the centre, and it reduces weight as less strengthening is needed further out. But it also rakes backwards (known as wing sweep), this is a stability thing, where sweep increases stability both in pitch, yaw and to a slightly lesser extent roll. It also allows aircraft to cruise at a higher mach number before supersonic effects take over.
So the reference planform I chose is here, The flaps cover 60% of the span, with the leading edge slats outboard of that, shown at a suitably high angle of attack to see how it goes. The wing was modelled in 'Alias Automotive'...which was just so fun
Next up is actually properly integrating that with the fuselage. The IP rights are now mine again so I am free to show off the actual design now
Stay tuned
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Training jet fuselage, now with 50% more plane
Okay then. So let's look beyond that now, I can work on the proper aircraft form.
So, here's what it looked like based on the results of the wing test
So it's taken a drastic leap. Explanation below, copy pasted from the coursework because I'm quite lazy:
The aircraft will sit on the ground with a 2 degree nose-down attitude, this is to minimise unwanted lift from the wings as a result of gusting causing difficulty to the pilot during taxiing manoeuvres as well as improved forward visibility from both seats.
There are multiple changes to the initial fuselage design, notably the elongated and sharper nose cone and wider, blunter tail. Also because of limited fuselage space and the need for good rear seat visibility, the canopy has been made taller to accommodate a raised rear seat.
There is insufficient space to accommodate the retracted nose gear underneath the cockpit; as such it must retract forwards into the nose cowling.
A crease from the nose to over the leading edge strake will provide assistance in generating vortex flow.
The leading edge strakes are longer than the reference area and form an ‘S’ curve to improve pilot visibility from both seats, raise the sweep angle and thus leading edge vortex strength whilst retaining the required exposed area. The strake also blends with the fuselage to maximise lifting potential and minimise interference drag.
Engine intake shape has been altered in lieu of leading edge strake placement; as such they are now fitted underneath the strakes to allow airflow to be delivered to the compressor face cleanly at high angles of attack and are rounded and enlarged.
The body has been widened to accommodate the main landing gear, which must also retract forwards. In a further attempt to shorten the wheelbase, increase longitudinal taxi stability and to ensure that on landing the forces through the landing gear leg are entirely axial, a forward rake angle of approximately 11 degrees has been included.
The wing trailing edge Yehudi will serve to blend the wing with the fuselage at its trailing edge.
The engine exhausts are further forwards and entirely shrouded from the top by the fuselage and the horizontal tails have been moved inboard. The vertical tails have also been canted outwards by 25 degrees to provide further longitudinal stability.
A bit more to come later
So, here's what it looked like based on the results of the wing test
So it's taken a drastic leap. Explanation below, copy pasted from the coursework because I'm quite lazy
:The aircraft will sit on the ground with a 2 degree nose-down attitude, this is to minimise unwanted lift from the wings as a result of gusting causing difficulty to the pilot during taxiing manoeuvres as well as improved forward visibility from both seats.
There are multiple changes to the initial fuselage design, notably the elongated and sharper nose cone and wider, blunter tail. Also because of limited fuselage space and the need for good rear seat visibility, the canopy has been made taller to accommodate a raised rear seat.
There is insufficient space to accommodate the retracted nose gear underneath the cockpit; as such it must retract forwards into the nose cowling.
A crease from the nose to over the leading edge strake will provide assistance in generating vortex flow.
The leading edge strakes are longer than the reference area and form an ‘S’ curve to improve pilot visibility from both seats, raise the sweep angle and thus leading edge vortex strength whilst retaining the required exposed area. The strake also blends with the fuselage to maximise lifting potential and minimise interference drag.
Engine intake shape has been altered in lieu of leading edge strake placement; as such they are now fitted underneath the strakes to allow airflow to be delivered to the compressor face cleanly at high angles of attack and are rounded and enlarged.
The body has been widened to accommodate the main landing gear, which must also retract forwards. In a further attempt to shorten the wheelbase, increase longitudinal taxi stability and to ensure that on landing the forces through the landing gear leg are entirely axial, a forward rake angle of approximately 11 degrees has been included.
The wing trailing edge Yehudi will serve to blend the wing with the fuselage at its trailing edge.
The engine exhausts are further forwards and entirely shrouded from the top by the fuselage and the horizontal tails have been moved inboard. The vertical tails have also been canted outwards by 25 degrees to provide further longitudinal stability.
A bit more to come later
-
jamesmc
- Captain
- Posts: 1776
- Joined: 08 Jul 2009, 15:35
Re: Trainer Jet WIP
Fascinating details, enjoyed reading the technical aspects and the results.
Quite the lovely design on the model as well.
The image below is where I worked for awhile about thirty years ago. (human centrifuge)
The Human factor is often the limiting factor in aircraft design (if a human is in the craft). People tend to lose their eye level blood pressure on high turns and twists causing loss of consciousness.
In the early times of 1960s it was used to test G(y) forces on astronauts. They were laying down as they would at take-off. Was an award called "Order of the Elephant" (15 G(y) forces across the torso).
Since fighter pilots don't like to lay on their back to fight, they have upright seats, so we tested the G(z) forces that pilots took on tight turns and anti-combat maneuvers. Most common profile was 3 to 5 to 9 G(z) up and down for about a minute.
Saw a lot of folks come through there, NASA, Air Force, Navy, Foreign military, etc. That old centrifuge had 4 - 250 HP DC electric motors on it. It could roll your socks down in a hurry.
Humans would ride in that enclosed gondola. There other end was for instruments and animals tested.
Quite the lovely design on the model as well.
The image below is where I worked for awhile about thirty years ago. (human centrifuge)
The Human factor is often the limiting factor in aircraft design (if a human is in the craft). People tend to lose their eye level blood pressure on high turns and twists causing loss of consciousness.
In the early times of 1960s it was used to test G(y) forces on astronauts. They were laying down as they would at take-off. Was an award called "Order of the Elephant" (15 G(y) forces across the torso).
Since fighter pilots don't like to lay on their back to fight, they have upright seats, so we tested the G(z) forces that pilots took on tight turns and anti-combat maneuvers. Most common profile was 3 to 5 to 9 G(z) up and down for about a minute.
Saw a lot of folks come through there, NASA, Air Force, Navy, Foreign military, etc. That old centrifuge had 4 - 250 HP DC electric motors on it. It could roll your socks down in a hurry.
Humans would ride in that enclosed gondola. There other end was for instruments and animals tested.
- Attachments
-
Walk by faith, not by sight.
-
Steve
- Master Chief Petty Officer
- Posts: 394
- Joined: 29 Jun 2009, 10:20
- Type the number ten into the box: 0
- Location: Hiding (Like a ninja)
Re: Trainer Jet WIP
Seen a test done in a similar sort of gondola on something called the Giraffe suit, featurers a whole heap of water filled capillaries running along a full body suit to increase pilot g tolerance. In the test this guy put it up to 9 G and sustained it for 30 seconds, then the test engineer took over and put it up to 11...whilst the pilot then took out a rubiks cube and solved it!. I've pulled 5 in a plane and it's certainly not a pleasant experience so I can't imagine 11!
This aircraft is nominally designed to operate with current G-suit equipment, though I know that'll only increase G-tolerance for a bit, maybe by 1 or 2 if you're lucky. Though I see the modern bang seats cant the pilot back by about 15 degrees, which probably helps quite a bit.
In reality though, it's doubtful whether this aircraft will go up to the 8g limit load required normally, unless the pilots are being utter hooligans.
This aircraft is nominally designed to operate with current G-suit equipment, though I know that'll only increase G-tolerance for a bit, maybe by 1 or 2 if you're lucky. Though I see the modern bang seats cant the pilot back by about 15 degrees, which probably helps quite a bit.
In reality though, it's doubtful whether this aircraft will go up to the 8g limit load required normally, unless the pilots are being utter hooligans.
-
RAYMAN
- Captain
- Posts: 2547
- Joined: 21 May 2009, 18:56
Re: Trainer Jet WIP
I saw one of these in 1972 at Nasa space center in Houston...... 
that was in the golden days of spaceflight...
Peter
that was in the golden days of spaceflight...
Peter