CGI - Possible configuration of the Boeing F-47 NGAD

[DWG]

If you could pick-up the F-16, flight loaded. at the CG (think Jolly Green Giant - lol) to determine how the aircraft balances, it would fall on its tail.

If that happens, then you aren't picking it up at the CofG, the CofG is by definition the point at which it balances.

 

[FlyGuy369]

Tell me more!

Found this some time ago, Details the use of compressed air injection to offset the Shockwave at the intake much like a DSI would, very interesting like the air injection variable exhaust was.

Link:

https://patents.google.com/patent/U...r)(inlet)(aircraft)&assignee=Boeing+Co&page=6

 

[Scott Kenny]

See post #678

As long as those ejection angles are the same as you get from the EWP, I'll buy it.

I never said two of those would fit side by side

Then I grossly misunderstood. I had understood you to say that each bay could hold two JASSMs or AARGM-ERs.

Bay-wise, I wouldn't necessarily be surprised if F-47 ended up with one of the FB-22 bay sizes.


My personal favorite is actually FB-22-1, assuming that part of the fuselage stretch was ~2ft forward of the wings to allow for carrying AMRAAMs in the side bays (or however long a stretch that actually requires). The widened fuselage is so that there's space for a single GBU-28 on the centerline, plus a 2000lb on each side. For the 2000lb side, that doesn't add any bay width, just bay depth. A GBU-28 is 20ft long. What I'd want to do is add enough extra length in the bay to also be able to carry a pair of SDBs in the aft part of that bay, so that 6xSDBs is a centerline option.

Anyways, the more interesting option is probably the accommodation of future Expendable CCA / Remote Carriers.

Very much so.

 

[djfawcett]

If that happens, then you aren't picking it up at the CofG, the CofG is by definition the point at which it balances.

OOOOpppppssss - You are right. I should have said AC. The CG (mass centroid) would be aft of the AC meaning negative stability margin. That mistake is what happens when rushing and not paying attention.

 

[F119Doctor]

If that happens, then you aren't picking it up at the CofG, the CofG is by definition the point at which it balances.

I’m sure they meant “if you picked the F-16 up at the center of lift, it would fall on its tail”

The F-16 is statically unstable at lower AOA (this changes at 25+ degrees AOA) while subsonic - the tail is lifting.

Supersonic, the center of lift moves aft (from quarter chord to half chord in classical aero theory), making the CG forward of the center of lift and the aircraft statically stable, with a down load on the tail. But less of a download than of the aircraft was statically stable subsonic. The F-4 could not pull more than 5G supersonic because the stabilizer ran out of downward pitch capability. But you would over-G the aircraft if it went subsonic with the stick pulled all the way back during the initially supersonic turn.

There are multiple variations on subsonic static stability - stable, neutral stability, slightly unstable, highly unstable.

 

[Scott Kenny]

Some ideas from the FCAS thread.

Another pic and video of the Onera concepts... I like the 2 Loyal Wingmen:

• Heavy fighter with LEVCONs (top), also known as "Superman" concept
• Loyal wingman "stealth bomber" (right)
• Loyal wingman fighter (left)... described as "not too sophisticated" (i.e. attritable)
• "Low cost" drone (bottom) for decoy missions, electronic warfare, and saturation of air defenses (apparently unarmed)

View: https://youtu.be/ezvav4zZIdQ

(apologies if the picture doesn't show naturally in the thread)

That stealth bomber on the right makes me wonder if the F-47's inlets and planform is going to look like that. Afterall it does have a shovel nose and the shape found in a lot of past renders.

I think that the F-47 will have the intakes on the bottom of the airframe, so that they get less airflow disruption during pitch-up maneuvers. A bomber mission doesn't need a lot of pitch-up, basically only at takeoff and landing, while a fighter maneuvers a lot more.

 

[VTOLicious]

...
Bay-wise, I wouldn't necessarily be surprised if F-47 ended up with one of the FB-22 bay sizes.
View attachment 775250

My personal favorite is actually FB-22-1, assuming that part of the fuselage stretch was ~2ft forward of the wings to allow for carrying AMRAAMs in the side bays (or however long a stretch that actually requires). The widened fuselage is so that there's space for a single GBU-28 on the centerline, plus a 2000lb on each side. For the 2000lb side, that doesn't add any bay width, just bay depth. A GBU-28 is 20ft long. What I'd want to do is add enough extra length in the bay to also be able to carry a pair of SDBs in the aft part of that bay, so that 6xSDBs is a centerline option.

Planform of FB-22-1 bears a strong resemblance to Su-57.

 

[Scott Kenny]

Planform of FB-22-1 bears a strong resemblance to Su-57.
View attachment 775329

Yeah, a little bit.

 

[targetpractice]

I've enhanced the contrast a bit and noticed some things that weren't evident in the initial pictures

This does make me think we're looking at BOPMAX

 

[Seragina]

If we combine these calculations with F119 engine, then
- RATED 138.6 Kg/s air passes through it at sea level & standard conditions, stationary engine & produces dry thrust 116 KN.
- Moving engine to 20K ft. but stationary, reduces AMF & thrust by (6.75/14.7), so dry thrust = 53.27 KN, AMF = 63.64 Kg/s.
- Accelerating engine to Mach 0.9 at 20K ft, changes AMF & thrust by (11.42/14.7), so dry thrust = 90.12 KN, AMF = 107.67 Kg/s.
- Coming down at sea level, Mach 0.9, changes AMF & thrust by (24.86/14.7), so dry thrust = 196.17 KN dry & AMF = 234.39 kg/s. Is this thrust & AMF value true or possible for F119?

The F-22 would achieve Mach 1.8 supercruise at mid-altitude, let's consider 35K ft, where atmospheric pressure is 3.53 psi & temp. is -65.6 F / -54.2 C / 218.9 K. But IDK how to calculate Pt2 & T2.

The engine thrust behaviour look like these:





Aside from detailed parameters it's necessary to match them with proper known F22 flight data.
At SL at MIL it's designed for 800 kts ~M1.21
and MIL at altitude it's 1044 kts ~M1.81
M2.0 at 40000 ft at 118% throttle
AB being 150% throttle.

 

[Seragina]

Once the aircraft starts moving with the airflow aligned with the intake, you are probably back up to the 14.7 psi around M 0.3, and the increasing with additional Mn.

Is there a specific reason why modern engine can't start working at M0.15 as older engines?

 

[Seragina]

Also, JASSMs (and AARGM-ERs) are significantly wider than 2000lb JDAMs, ~25" versus ~19". Plus you need room for the bomb techs to reach around the ordnance to lock it onto lugs, tighten bolts, and connect data umbilicals.

That's not how weapons are loaded into a bay any longer. These day they are attached first and then hoisted via an internal hook-line system. So the techs don't necessarily need to get into tight spaces.

See post #678
I never said two of those would fit side by side

Anyways, the more interesting option is probably the accommodation of future Expendable CCA / Remote Carriers.

Imho having carriers inside is wasteful and probably not really going to be used a lot by the F47. I'm fine with them being outside and let loose long before getting into detection range. And with CCA around they are kind of redundant.
From what I see the futue ones will have around 500 km range so they could be launched en mass by a B1.

 

[Seragina]

As long as those ejection angles are the same as you get from the EWP, I'll buy it.



Then I grossly misunderstood. I had understood you to say that each bay could hold two JASSMs or AARGM-ERs.

Bay-wise, I wouldn't necessarily be surprised if F-47 ended up with one of the FB-22 bay sizes.
View attachment 775250

My personal favorite is actually FB-22-1, assuming that part of the fuselage stretch was ~2ft forward of the wings to allow for carrying AMRAAMs in the side bays (or however long a stretch that actually requires). The widened fuselage is so that there's space for a single GBU-28 on the centerline, plus a 2000lb on each side. For the 2000lb side, that doesn't add any bay width, just bay depth. A GBU-28 is 20ft long. What I'd want to do is add enough extra length in the bay to also be able to carry a pair of SDBs in the aft part of that bay, so that 6xSDBs is a centerline option.



Very much so.

With what I've drawn so far FB-22-1 and FB-22-2 are best fit and most desired choices.
But due to spacing I'm not so certain having SDBs in the side bays will work out.
My A2G option for the "light" version end up with 15 klbs (rounded):

The racks for the SDB types are weighting too much: loaded 4-rack weights ~1500 lb so it needs to use the rack for 2000 lb class store to be mounted. This needs a newer more compact and lighter design. That could save 500-1000 lb in the calculation. Also in many cases AIM-260 needs folded wings.

 

[Scott Kenny]

With what I've drawn so far FB-22-1 and FB-22-2 are best fit and most desired choices.
But due to spacing I'm not so certain having SDBs in the side bays will work out.

I would not expect SDBs in the side bays, those are for BVRAAMs only IMO.

My A2G option for the "light" version end up with 15 klbs (rounded):
View attachment 775605
The racks for the SDB types are weighting too much: loaded 4-rack weights ~1500 lb so it needs to use the rack for 2000 lb class store to be mounted. This needs a newer more compact and lighter design. That could save 500-1000 lb in the calculation. Also in many cases AIM-260 needs folded wings.

For the FB-22-1 airframe/bay, I was assuming that the weapons would be forward in the bay, and that only the center third of the bay would be long enough for a 5000lb weapon. So that today, if you were not carrying a GBU-28/GBU-72, you'd stick a 2000lb weapon on centerline and have space for a pair of SDBs on a half-length behind it. Or, stick the standard 4xSDB rack on the centerline and have a half-length 2xSDB rack behind it.

This would keep the heaviest weapons forward of the MLG.

 

[Scott Kenny]

That's not how weapons are loaded into a bay any longer. These day they are attached first and then hoisted via an internal hook-line system. So the techs don't necessarily need to get into tight spaces.

That certainly makes life easier for an Ordie!

 

[Seragina]

I would not expect SDBs in the side bays, those are for BVRAAMs only IMO.



For the FB-22-1 airframe/bay, I was assuming that the weapons would be forward in the bay, and that only the center third of the bay would be long enough for a 5000lb weapon. So that today, if you were not carrying a GBU-28/GBU-72, you'd stick a 2000lb weapon on centerline and have space for a pair of SDBs on a half-length behind it. Or, stick the standard 4xSDB rack on the centerline and have a half-length 2xSDB rack behind it.

This would keep the heaviest weapons forward of the MLG.

It's not a problem as far as fitting goes, just less space efficient and imho would be more stressfull or rather more g-force restrictive.
As for MLG it's always behind the CG & AC so this isn't a problem or any designs everyone made so far as they are all behind the IWB ragardless.

 

[Low IQ Techie]

I would recommend downloading a copy of the Pratt & Whitney Aeronautical Vest Pocket Handbook. https://www.scribd.com/document/279...-Handbook-Pratt-Whitney-22nd-Edition-Sep-1991

From knowledgable guys like some of you my expectation was a labeled diagram, an online calculator.
But anyways, Thanks, that's a useful doc.
I guess i'll have to do all the homework. Knowledge of right keywords is very important for a precise & fast google search.
But that free trial still asks for credit/debit card #
And it throws ads at every few pages

In the Handbook there are lots of formulas on jet engine and rocket engine performance to keep you busy for a month, at least. In addition, there is a table show showing standard ram recovery values of PT2 and TT2 at various Mn and altitudes from see level static to M3 / 80k ft. These values are based on a design Mil Spec and may represent the best case, with all inlet designs being less than optimum. Real world inlets will probably have lower ram recovery and higher temperatures when operating outside their design Mn.

With huge patience i managed to get some useful 51 pages screenshots, some formulas i already saw on Glenn Research center site & other Google searched sites.
And just after my previous reply i discovered the "Isentropic table" which you are talking about here.

The following are some NASA-GRC diagrams



OBSERVATIONS -
> P/Pt is also shown related to T/Tt as P/Pt = (T/Tt)^(y/y-1). They just need Mach # as I/p. It means the ratio value will remain constant at all altitudes at same Mach #.
- A* is area of throat at Mn=1; A is area at arbritary position.
- Now bcoz A/A* formula is derived from equating AMF formula at Mn=1 (max AMF) & at any other Mn at any other area A, means AMF remains constant at any area. The density, velocity, pressure vary.
Constant AMF throughout the CD duct = Area X Velocity X Density. A1.V1.D1 = A2.V2.D2
- While converging the velocity & area decreases, pressure & density increases, temp. increases.
- While diverging the velocity further decreases, area & pressure increases, temp increases further.




So P0 < P.th < P2
or Atmosperic pressure < Throat pressue < Inlet pressure

At take-off with 100% MIL power, the A/c or engine is stationary, but the intake air flow is sucked in at certain high velocity, then reduced to Mn 1 at throat, then reduced further at inlet.

At 35,000 ft, atmospheric P&T are known, considered velocity will be SuCr Mach 1.8 with 100% MIL power, but intake area not known.

But as i said, my expectation was an online calculator & i found many -

https://www.omnicalculator.com/physics/isentropic-flowhttps://www.particleincell.com/2014/turbofan-calculator/https://onlineflowcalculator.com/pages/THRUST/calculator.htmlhttps://www.grc.nasa.gov/www/k-12/airplane/mflchk.htmlhttps://www.grc.nasa.gov/www/k-12/airplane/isentrop.htmlhttps://www.grc.nasa.gov/www/k-12/airplane/astar.htmlhttps://www.grc.nasa.gov/www/k-12/airplane/airsim.htmlhttp://www.flowillustrator.com/turbofan-calculator-for-public-use.phphttps://aerospaceweb.org/design/scripts/compress.shtmlhttps://saemiller.com/flow/SAEMiller_Comp_Calc.htmlhttps://cdgriffin.me/compressible.phphttps://www.pdas.com/flowcalc.htmlhttp://www.ae.metu.edu.tr/~bseymen/aero.htmhttps://srm-aero.weebly.com/aerodynamics-calculator.htmlhttps://www.engineering-4e.com/compressible-flow-calculatorhttps://aerodynamics4students.com/gas-dynamics-and-supersonic-flow/table2.phphttps://www.compressibleflowcalculator.com/isentropicflow

I'll give some example screenshots, rest people can visit.

Isentropic calculator at that A/A* webpage.
(https://www.grc.nasa.gov/www/k-12/airplane/astar.html)

For SuCr Mn 1.8,
P/Pt = 0.1740 but recipocal Pt/P or P2/P0 = 5.745
T/Tt = 0.607 but recipocal Tt/T or T2/T0 = 1.647

The T&P formulas need only Mach #



So at 35k ft,
P0 = 24.33 KPa, calculated P2 = 24.33 x 5.745 = 139.77 KPa
T0 = 218.9 K, calculated T2 = 218.9 x 1.647 = 360.52 K
For P2, T2 we don't know speed before inlet.

If we put P0, T0, M 1.8 in AMF calculator
(https://www.grc.nasa.gov/www/k-12/airplane/mflchk.html)



Some error prevents from increasing area input.

So 21.478 Kg/s for 0.464515 sqm,
36.29 Kg/s for 0.785 sqm
This is way too less for MIL power !!


At sea level,
IDK max SuCr speed at sea level, let's consider Mach 1.21
Putting this in Isentropic calculator



P2/P0 = 1/0.4070 = 2.457
T2/T0 = 1/0.774 = 1.291

P0 = 101.35 KPa, calculated P2 = 101.35 x 2.457 = 249 Kpa
T0 = 288.15 K, calculated T2 = 288.15 x 1.291 = 372 K
For P2, T2 we don't know speed before inlet.

Putting P0, T0, M 1.21 in AMF calculator



For 0.464515 sqm it is 108.583 Kg/s
so for 0.785 sqm AMF is 183.5 Kg/s
How is this possible if quoted figure of 100-140 kg/s for various engines are supposed to be at sea level, STP?


-------------------------------------------------------------------------------------------------------------
Turbofan calculator
(https://www.particleincell.com/2014/turbofan-calculator/)

Wow, this one takes so many inputs.
I adjusted values of F119 engine at 35,000 ft., Mach 1.8
Atmospheric T&P 218.9 K, 24.33 KPa,
OPR 26, Heating value of JP-8 fuel 42.8 MJ/Kg, TET 1922 K, BPR 0.3

It doesn't take I/p of area, or give O/p.

So it gave O/p:
T02 360.75 (K) Compressor Inlet Temperature
p02 139795.22 (Pa) Compressor Inlet Pressure
Tma 792.96 (N/kg/s) Thrust per air mass flow rate
TSFC 2.98e-5 (kg/s/N) Fuel flow rate per thrust

P2/P0 = 139795.22/24330 = 5.745
T2/T0 = 360.75/218.9 = 1.648
same as in previous calculator

If AMF is taken 138.6 Kg/s then 100% MIL power = 138.6 X 792.96 = 109.9 KN, < 116 KN Rated.
If 116 KN thrust is taken then AMF = 116000/792.96 = 146.28 Kg/s > 138.6 Kg/s.
But these values are at least nearby, unlike previous calculator. How can NASA's calculator mess up? I must have made some blunder mistake.




----------------------------------------------------------------------------------------------------------------------
(http://www.flowillustrator.com/turbofan-calculator-for-public-use.php)

This one also takes in y=1.4, M = 1.8 & give O/p of P2/P0 & T2/T0 same as above.



So different calculators are giving slightly different values.
May be due to quick calculations, otherwise precise i/p will give same values.
We need patience.

I can’t answer all of your questions, but the inlet duct Mn at the engine face is usually in the 0.6 to 0.8 range. While the airflow inside the inlet duct must be subsonic, the speed of the fan blade tips is not limited to M1. The J91 was the first P&W engine with a transonic compressor, with the blade tips running beyond M1. The J58 was originally an 80% scaled down version of the J91, and the first two stages of the J91 compressor were used in place of the first three stages of the J57 to create the TF33/JT3D turbofan engine. From what I understand, most turbofan engines are designed with the first stage blade tips moving thru the inlet air at approximately M1.4.

Well, that's a shocker to me that blade tips can cross Mn1. I wonder how did they deal with shock waves, sonic drag causing vibrations & shattering. But present day it seems makers may wan't to keep tip speed below Mn1, say Mn 0.9 or 0.8 as safety margin.
May be that's relative contact closure velocity.

I forgot to mention that AMF depends not just on inlet area, intake area but also on efficient blade design of fan, LPC, HPC. Different engines with same fan area but different blade design will have different AMF & OPR (Overall Pressure Ratio) or Compression Ratio.
That's where VELOCITY TRIANGLE come into play.




If tip is at M1 & air also at M1 then they constitute an isoceles triangle of vectors, so their relative closure velocity = 1.cos(45) + 1.cos(45) = Mn 1.4, or sqrt(1^2 + 1^2) by Pythogoras theorem.
The relative air-tip contact velocity is Mn 1.4
If tip moves at Mn 0.9 & air flow at Mn 0.4 then relative contact velocity = sqrt(0.9^2 + 0.4^2) = Mn 0.98
So if relative contact velocity also needs to be max Mn1 then for Mn 0.9 tip speed, air flow speed = sqrt(1^2 - 0.9^2) = Mn 0.43
So either higher limit of tip speed or of air flow but not both.

Relative air-blade contact closure velocities​
		tip speed​	Mach​
		0.3	0.4	0.5	0.6	0.7	0.8	0.9	1
air flow speed​	0.3	0.424264​	0.5​	0.583095​	0.67082​	0.761577​	0.8544​	0.948683​	1.044031​
Mach​	0.4	0.5​	0.565685​	0.640312​	0.72111​	0.806226​	0.894427​	0.984886​	1.077033​
	0.5	0.583095​	0.640312​	0.707107​	0.781025​	0.860233​	0.943398​	1.029563​	1.118034​
	0.6	0.67082​	0.72111​	0.781025​	0.848528​	0.921954​	1​	1.081665​	1.16619​
	0.7	0.761577​	0.806226​	0.860233​	0.921954​	0.989949​	1.063015​	1.140175​	1.220656​
	0.8	0.8544​	0.894427​	0.943398​	1​	1.063015​	1.131371​	1.204159​	1.280625​
	0.9	0.948683​	0.984886​	1.029563​	1.081665​	1.140175​	1.204159​	1.272792​	1.345362​
	1	1.044031​	1.077033​	1.118034​	1.16619​	1.220656​	1.280625​	1.345362​	1.414214​

IDK the exact tip speed but here combinations like -
- the tip speed of Mn 0.9 + AMF speed of Mn 0.4 = contact velocity of Mn 0.98,
- or tip speed of Mn 0.8 + AMF speed of Mn 0.5 = contact velocity of Mn 0.94,
looks good.

That's why, when i searched for some videos for explanation i did find them mentioning also that for the tip speed & contact velocity to be below Mn 1 the AMF speed need to be around Mn 0.4





Hence no matter whatever be the max speed of a jet like that of F-15, F-22, MiG-25, SR-71, XB-70, etc, the inlet air has to slow down around Mach 0.4 by oblique & normal shocks, intake being designed accordingly.

I've not read more deeply yet if the fan & LPC blades are movable to match relative direction of air flow.

When we search "Isentropic Flow graph" we get numerous graphs, something more interesting -



OBSERVATIONS -
- The A/A* or A*/A line is max/min at M#=1, the throat.
- On both sides are set of subsonic & supersonic speeds.
- Hence for a design supersonic speed, there is also a subsonic speed in graph in same horizontal level.
- At these 2 point on area ratio line, the values are same, or A2/A* = A0/A* or A2 = A0.
- Decreasing intake area won't achieve design speed.
- Increasng intake area won't increase speed bcoz engine has limits of AMF due to RPM, OPR, TET, etc.

This further indicates that AMF speed before inlet would be around Mach 0.4-0.5

So in case of F-22 designed for M 1.8 SuCr, intake & inlet area are perhaps same, needs confirmation.
At 35K ft., Mach 1.8 X Intake Area X air density = AMF speed X inlet area X air density before inlet.

If intake & inlet area same then A0 = A2, or A0/A* = A2/A* = 1.439 as given by Isentropic calculator before.
Checking values by trial & error, M 0.454 causes same A/A* value.



So at 35 ft,
P2 calculated was 24.33 x 5.745 = 139.77 KPa
T2 calculated was = 218.9 x 1.647 = 360.52 K

Putting P2, T2, M 0.454 in AMF calculator



This AMF value 96.15 Kg/s for 0.464515 sqm doesn't match value for P0, T0, M 1.8

Mistake has to be rectified.

Anyways, the volume of air passing through F119 inlet at Mach 0.454 = 0.785m2 X 155.72m = 122.24m3 of air.
Now it is the pressure & temperature which will decide AMF.

If 138.6 Kg/s is AMF at sea level, then density before inlet = 138.6/122.24 = 1.1338 Kg/m3, while the atmospheric air density at sea level is 1.225 Kg/m3.

There can be many calculations but all parameters need to be put into table at 3 situations -
- A/c stationary, ready for T/o at MIL power.
- A/c flying at sea level with MIL power.
- A/c flying at 35K ft. at M 1.8

I will also caution you that F119 engine airflow, pressure ratio, rotor speeds, turbine inlet temperatures have never been publicly released. Using Chinese guesses will just make your guesses just that more inaccurate.

Ofcourse, secrecy is natural. But we're in era of globalization, international education & preofession, information proliferation, publications + public global arenas. So people will make uneducated & educated guesses.

The aim is to map throttle 100%/AB to AMF, SFC, Thrust, inlet area, intake area, that's all.
Ultimately it comes down to chemical reaction equation -
Fuel + Air => Heat + K.E.(Thrust)
So how much fuel & Air needed for particular dry/wet thrust & engine size?

The F110-132 airflow would be that value at sea level, zero Mn, 15C on the test cell with a zero loss bellmouth. When installed, the actual airflow will be less due to the aircraft inlet restriction bringing the inlet pressure below the 14.7 psi standard number. Once the aircraft starts moving with the airflow aligned with the intake, you are probably back up to the 14.7 psi around M 0.3, and the increasing with additional Mn. But, the faster you go, the higher the inlet temperature. In addition, the installed engine is supplying bleed air and gearbox horsepower to the airframe, both of which increase TIT and move it closer to the limit. The effect is relatively small at low altitudes, but become a larger and larger percentage impact as the aircraft goes higher and slower.

Hmm, the faster we go, the higher will be inlet temp., that's in denominator of AMF formula.
The Mn is there in both numerator & denominator.
Pressure decreases with altitude but increases in CD duct before inlet, which is in numerator.
So we may have to look at some graphs.

 

[Seragina]

Nice, work.

From knowledgable guys like some of you my expectation was a labeled diagram, an online calculator.

It's not simple to get everything into one single graph. Even the simple altitude-speed graph would be full with Reynolds lines, speed, wind lines, excess-thrust-aircraft-performance lines, and climb-lines. Tons of parameters right there let alone all the atmospheric, SFC, engine behavior etc.

For 0.464515 sqm it is 108.583 Kg/s
so for 0.785 sqm AMF is 183.5 Kg/s
How is this possible if quoted figure of 100-140 kg/s for various engines are supposed to be at sea level, STP?

Well, most online NASA calculators aren't good by design. They serve to educate and are clearly limited to prevent abuse.
It's all according to law passed by congress especially the obfuscation against adversary nation.

The aim is to map throttle 100%/AB to AMF, SFC, Thrust, inlet area, intake area, that's all.
Ultimately it comes down to chemical reaction equation -
Fuel + Air => Heat + K.E.(Thrust)
So how much fuel & Air needed for particular dry/wet thrust & engine size?

Well, the SFC has been set as part of the ATF requirement so we do have them floating around:
dry SFC 0.61 lb/hr/lbst (17.28 mg/Ns)
maximum SFC 2.35 lb/hr/lbst (66.57 mg/Ns)
We know the chemical ideal mix is 12:1 JP8 and since we know the temperature we know the fuel:air ratio should be around 0.02.
We just need to match the numbers.

 

[targetpractice]

Need to bring in the chine extension a little, but this feels closer.

 

[FlyGuy369]

This is giving me the original F-X concept vibes plus canards

 

[Scott Kenny]

Need to bring in the chine extension a little, but this feels closer.

View attachment 775717View attachment 775718

I still feel like the hangar image has the camera above the aircraft waterline, so that part of the apparent dihedral comes from the leading edge sweep.

 

[targetpractice]

I still feel like the hangar image has the camera above the aircraft waterline, so that part of the apparent dihedral comes from the leading edge sweep.

For the longest time I agreed with you, and even now there is tiny, rational voice in my head that suspects this to be true, but. BUT. Having pushed this around for a while now, there is so much in the official renders that can only be explained by really weird wings.

 

[Scott Kenny]

For the longest time I agreed with you, and even now there is tiny, rational voice in my head that suspects this to be true, but. BUT. Having pushed this around for a while now, there is so much in the official renders that can only be explained by really weird wings.

I'm not doubting that the wings aren't dihedral to some degree. I'm just doubting that they're as extremely dihedral as most people are guessing. Like maybe 2/3rds the angle you've got.

But if someone makes a full 3d model I will be happy to be proven wrong!

 

[Low IQ Techie]

Nice, work.

It's not simple to get everything into one single graph. Even the simple altitude-speed graph would be full with Reynolds lines, speed, wind lines, excess-thrust-aircraft-performance lines, and climb-lines. Tons of parameters right there let alone all the atmospheric, SFC, engine behavior etc.

Well, most online NASA calculators aren't good by design. They serve to educate and are clearly limited to prevent abuse.
It's all according to law passed by congress especially the obfuscation against adversary nation.

Well, the SFC has been set as part of the ATF requirement so we do have them floating around:
dry SFC 0.61 lb/hr/lbst (17.28 mg/Ns)
maximum SFC 2.35 lb/hr/lbst (66.57 mg/Ns)
We know the chemical ideal mix is 12:1 JP8 and since we know the temperature we know the fuel:air ratio should be around 0.02.
We just need to match the numbers.

We don't need to put everything in a graph.
We need to observe just a few graphs & make table for just 3 conditions, theoretically, at positions outside intake & inlet, that's it.
Formulas with A* consider throat, while P2/P0, T2/T0, D2/D0 don't.

There are many colleges offering Aero-degree around the globe today.
US Congress cannot control all those colleges, professors, students.
The info which i found are basic level. I watched some university videos also how those formulas were derived. Even the non-tech grads will understand it.

We can manually calculate on paper with y=1.4 for air, desired Mn, T&P values at altitude to check if the calculators have been made correctly or not.

Formulas for air speed before & after crossing oblique & normal shock also there.

It is simple school physics - how many molecules for oxygen needed for fuel. And air has 21% O2.
JP-8 fuel has multiple compounds in it in certain %, but that's not needed. The fuel-air mix ratio must match SFC & AMF(21% O2) values.

IDK why pilots, Aero-professionals & students don't educate public, but apparenty in era of globalization, international education, info proliferation, at least the basic theoretical things will clear out & secrecy will shrink.

The new secrets are like - initially weight of F119 & F135 were reported less, but later, recently, silently updated to be far more, bcoz of additional components like cooling system, ceramic RF blockers, new AB system, new blade types, better combustion chambers, fuel, chemical composition, manufacturing techniques, etc.
Now things about these will gradually come out & the latest secret will be on 6gen VCE (Variable Cycle Engines), perhaps with morphing intake & exhausts.

But the theory of basic propulsion cannot remain secret for long when capabilities of a jet are claimed & colleges teach the subjects & put it on internet.

So we should try to make the table or put it in a block diagram.

 

[FlyGuy369]

Absolutely morphing exhausts and intakes. Here's my take on the F-47, atleast the start of. Angles and other considerations so far are based on real dimensions I've derived from real sources. There will be more to come.

 

[Low IQ Techie]

Need to bring in the chine extension a little, but this feels closer.

View attachment 775717View attachment 775718

Reminding a point i said earlier,
Canards means agility & dihedral wing means stability like in airliners.
While fighters have flat or slightly anhedral wings to be inherently unstable, to be managed by FCS.

CAD makers should always compare with some existing jet of their choice.
I always compare with F-22 being 2-engine, heavy class, best stealth fighter, having set many benchmarks w.r.t. RCS, agility, Supercruise, engine, certain sub-systems, etc.

So, when it is difficult to equalize by things like landing gear, intake, wingspan, length, then cockpit is best choice.



See we have a big problem here. The fuselage, intakes don't match, when equalized at cockpit.

Let me stretch F-47 width equal to F-22:



Now the fuselage size look better but cockpit size need reduction.

Wings too much dihedral.

 

[dark sidius]

Need to bring in the chine extension a little, but this feels closer.

View attachment 775717View attachment 775718

It realy look like the USAF rendering , good job.

 

[targetpractice]

Reminding a point i said earlier,
Canards means agility & dihedral wing means stability like in airliners.
While fighters have flat or slightly anhedral wings to be inherently unstable, to be managed by FCS.

CAD makers should always compare with some existing jet of their choice.
I always compare with F-22 being 2-engine, heavy class, best stealth fighter, having set many benchmarks w.r.t. RCS, agility, Supercruise, engine, certain sub-systems, etc.

So, when it is difficult to equalize by things like landing gear, intake, wingspan, length, then cockpit is best choice.

See we have a big problem here. The fuselage, intakes don't match, when equalized at cockpit.

Let me stretch F-47 width equal to F-22:


Now the fuselage size look better but cockpit size need reduction.

Wings too much dihedral.

I don't disagree it looks... lumpy. Some thoughts:

• At the moment I'm digging into the idea that the official images are presented in a misleading way, but essentially contain a real plane.
• On that assumption, I'm trying to make something that both matches the official images, and still looks like a vaguely sensible machine.
• My plane is approx. 20m long, mainly to accommodate some engines which are a bit bigger than F119s, and some big missiles. I was also thinking about the SU-57 and J-20 as good comparisons for role/range.
• Here's a side-by-side comparison with the F-22. The new canopy is definitely wider, but I feel it looks less wonky in the side and topdown views (please excuse the crappy renders)

• (Looking at it now, my plane is MASSIVE. I suspect the canopy would look even less whacky if I were to go for smaller engines and lopped a couple of metres off the length)
• Also worth noting that a bunch of the Boeing NGAD and FA-XX renders feature hugenormous canopies, so there is precedent for something similar here.

• Finally, the dihedral. I've argued against its existence in the past, but having pushed this model around for a while, I'm struggling to think of any other way of explaining what is in those images. Always happy to be proven wrong though!

 

[targetpractice]

I like the idea that there are a couple of Boeing engineers lurking here and rating our suggestions

 

[Low IQ Techie]

I don't disagree it looks... lumpy. Some thoughts:

• At the moment I'm digging into the idea that the official images are presented in a misleading way, but essentially contain a real plane.
• On that assumption, I'm trying to make something that both matches the official images, and still looks like a vaguely sensible machine.
• My plane is approx. 20m long, mainly to accommodate some engines which are a bit bigger than F119s, and some big missiles. I was also thinking about the SU-57 and J-20 as good comparisons for role/range.
• Here's a side-by-side comparison with the F-22. The new canopy is definitely wider, but I feel it looks less wonky in the side and topdown views (please excuse the crappy renders)

View attachment 775804

• (Looking at it now, my plane is MASSIVE. I suspect the canopy would look even less whacky if I were to go for smaller engines and lopped a couple of metres off the length)
• Also worth noting that a bunch of the Boeing NGAD and FA-XX renders feature hugenormous canopies, so there is precedent for something similar here.

View attachment 775806

• Finally, the dihedral. I've argued against its existence in the past, but having pushed this model around for a while, I'm struggling to think of any other way of explaining what is in those images. Always happy to be proven wrong though!

It is not about proving anybody right/wrong but thinking technically about technology, matching the size of components & overall jet.

BTW that cockpit looks wide enough for a sofa. Perhaps future ejection seats would be hybrid.
Sandwich compartment would be there. Tray table could be there.
The glass cockpit has wide screen.
The pilot can carry his favorites in thumb drive.

 

[targetpractice]

Absolutely morphing exhausts and intakes. Here's my take on the F-47, atleast the start of. Angles and other considerations so far are based on real dimensions I've derived from real sources. There will be more to come.

At some point one of us is going to accidentally design a full scale X-36

 

[Manuducati]

Need to bring in the chine extension a little, but this feels closer.

View attachment 775717View attachment 775718

Give it the outer wings anhedral it needs as a proud son of Bird Of Prey and I'll buy you two squadrons!

 

[targetpractice]

First sight of the XA103 engine. NGAD can also be seen in the video.

View: https://youtu.be/vCHun6rxQm0?si=GI8nwd6tdjXArDqf

 

[Rodrigo Avella]

It's my F/A-XX model that appears in the video, haha.
I'm amazed at how that model has been used. Even Collins Aerospace uses it as the official NGAD on its website.

 

[targetpractice]

I wonder if Boeing will also use your design?

 

[dark sidius]

It's my F/A-XX model that appears in the video, haha.
I'm amazed at how that model has been used. Even Collins Aerospace uses it as the official NGAD on its website.

Near the reality in fact , your design

 

[Reddington777]

It's my F/A-XX model that appears in the video, haha.
I'm amazed at how that model has been used. Even Collins Aerospace uses it as the official NGAD on its website.

And then they tacked the engines on there like a B-52 lol.

But that engine exhaust shape is fascinating. When I was working on my model earlier, I assumed the engine would be fairly close to the exhaust and the rear looked like the F-22 / J50.

The render I used though that was released by Boeing showed a much more tapered rear. That would mean either an aircraft much larger than the F-22 to allow the engine exhaust to taper towards a thin/ low profile exhaust outlet, or that the engines would need to be moved further forward into the fuselage to make room for the tapering, which may or may not mean a cramped weapons bay area.

I ended up going with the F-22 way because it made the most room for weapons.

 

[Hydroman]

From knowledgable guys like some of you my expectation was a labeled diagram, an online calculator.

OK everyone, I hope notes were taken, there will be a test, signed Al Gebra and Cal Culus.

 

[VTOLicious]

And then they tacked the engines on there like a B-52 lol.

But that engine exhaust shape is fascinating. When I was working on my model earlier, I assumed the engine would be fairly close to the exhaust and the rear looked like the F-22 / J50.

The render I used though that was released by Boeing showed a much more tapered rear. That would mean either an aircraft much larger than the F-22 to allow the engine exhaust to taper towards a thin/ low profile exhaust outlet, or that the engines would need to be moved further forward into the fuselage to make room for the tapering, which may or may not mean a cramped weapons bay area.

I ended up going with the F-22 way because it made the most room for weapons.

I've always assumed a flat nozzle, most likely including yaw TVC (+ flaps used for pitch/roll TVC at the rear end of the fuselage)...
https://www.secretprojects.co.uk/th...ion-of-the-boeing-f-47-ngad.45793/post-794740

 

[Yellow Palace]

Well, most online NASA calculators aren't good by design. They serve to educate and are clearly limited to prevent abuse.

Nah, they're just limited because they're educational tools that are illustrating an idealised condition. I'm actually surprised they're still up at all; those were around when I was in high school and trying to understand aeronautics for the first time.

I like the idea that there are a couple of Boeing engineers lurking here and rating our suggestions

It's more likely than you think. There are absolutely industry people on here, alongside the plagiarising journalists. Just obviously not discussing active projects.