Inward-turning Inlets

[XP67_Moonbat]

On The Design Of Inward-Turning Inlets

http://www.cfd4aircraft.com/int_conf/IC3/Papers/Croker.pdf

 

[airrocket]

Seems the Aussie rule 3D Busemann/Billig type axisymmetric flow-field inward compression inlet tech for now as the USAF appears to have backed off. Sannu Molder (Canada) who worked with Billig is "the man" in my book when it comes to inward inlets. Molder came up with (ICF) A and (ICF)B. Then there is also Ajay Kortari of Astrox who worked with Billig as well. Seems there was a kind of falling out and friction eventually between the two Billig and Kortari over the technology. These guys go back to the roots. Now there are many educated on the streamline traced techniques....DARA Lockheed early Blackswift concept utilized this technique in the design of the sugar scoop inlets. Billig, Czysz, Molder seemed to have formed a bond at some point in the past.

 

[Howedar]

Not sure why you'd ascribe inward-turning inlet design solely to the Aussies when the HyCAUSE inlet was designed in large part at the University of Minnesota and CUBRC in the US.

 

[DSE]

Seems the Aussie rule 3D Busemann/Billig type axisymmetric flow-field inward compression inlet tech for now as the USAF appears to have backed off. Sannu Molder (Canada) who worked with Billig is "the man" in my book when it comes to inward inlets. Molder came up with (ICF) A and (ICF)B. Then there is also Ajay Kortari of Astrox who worked with Billig as well. Seems there was a kind of falling out and friction eventually between the two Billig and Kortari over the technology. These guys go back to the roots. Now there are many educated on the streamline traced techniques....DARA Lockheed early Blackswift concept utilized this technique in the design of the sugar scoop inlets. Billig, Czysz, Molder seemed to have formed a bond at some point in the past.

Actually, if you are referring to the work of Dr. M. Smart at UQ, you might care to know that this work actually began during his tenure in the Hypersonic Airbreathing Propulsion Branch (HAPB) at NASA Langley Research Center in the late '90s. See the following page summarizing some of that work. http://hapb-www.larc.nasa.gov/Public/Engines/Rest/Rest.html.

While Dr. Smart left HAPB to return to UQ several years ago, this work continues and is the the subject of a collaborative effort between HAPB and UQ, which has had Dr R. Rollan in residence at HAPB for much of the past year. See http://www.uq.edu.au/news/?article=14533 and http://www.uq.edu.au/news/?article=15425. This is on going work supported by the Hypersonics Project in the NASA Fundamental Aeronautics Program.

 

[DSE]

Not sure why you'd ascribe inward-turning inlet design solely to the Aussies when the HyCAUSE inlet was designed in large part at the University of Minnesota and CUBRC in the US.

Not taking anything away from the HyCause effort though the flight test was not successful, the real crux is designing inlet systems which can start and operate with decent performance at substantially lower than their design Mach number. Hyper-X proved it was possible to use a point designed scramjet powered vehicle to accelerate at Mach 7 and cruise at Mach 10. Next one needs to prove a given design can operate over a range of Mach numbers.

 

[DSE]

Not sure why you'd ascribe inward-turning inlet design solely to the Aussies when the HyCAUSE inlet was designed in large part at the University of Minnesota and CUBRC in the US.

Or this L-Mart patent.

 

[DSE]

Found some newer papers on inward turning inlet work at LaRC.

Parametric Geometry, Structured Grid Generation, and Initial Design Study for REST-Class Hypersonic Inlets
and
Design of Modular, Shape-transitioning Inlets for a Conical Hypersonic Vehicle

links at the bottom of http://hapb-www.larc.nasa.gov/Public/Engines/Rest/Rest.html

 

[mz]

There's also some material on nianet, search something like site:nianet.org inward turning on google as the site doesn't make them findable. Attaching one as sample. Most of that material is mentioned in other contexts elsewhere on secret projects.

 

[DSE]

Note that the LaRC latest work I referenced has an NIA connection as one of the authors, a UQ grad is currently a visiting researcher, employed by the NIA.

 

[DSE]

There's also some material on nianet, search something like site:nianet.org inward turning on google as the site doesn't make them findable. Attaching one as sample. Most of that material is mentioned in other contexts elsewhere on secret projects.

Note that this is an abstract for a talk given in 2009. If you get the AIAA papers related to this work you find that while each and every streamline may be traced from a different compression field to get whatever shape is desired, by doing so it appears you have lost control over the compression ratio achieved according to one of my colleagues.

 

[shockonlip]

There's also some material on nianet, search something like site:nianet.org inward turning on google as the site doesn't make them findable. Attaching one as sample. Most of that material is mentioned in other contexts elsewhere on secret projects.

Thanks mz !

Imagine my shock when I see it was you who pointed this site out !

Cool stuff, thanks again !

 

[shockonlip]

... Sannu Molder (Canada) who worked with Billig is "the man" in my book when it comes to inward inlets. Molder came up with (ICF) A and (ICF)B. ...

Sorry airrocket for being so late on sending a thanks to you for this post.

I didn't know who Sannu Molder was until I started reading some ramjet/scramjet histories.

I suddenly realized that Sannu Molder was probably involved with the first effort ever,
to actually fly a scramjet, back in the 1960's and 1970's !! He mayu have even been the leader
of the effort, I don't know.

A nice writeup (enclosed below) can be found from:

HYPERSONIC AIRBREATHING PROPULSION: EVOLUTION AD OPPORTUNITIES (AGARD CP-428)
by P. J. Waltrup; The Johns Hopkins University Applied Physics Laboratory
...

Returning to the North American continent, interest in Canada in scramjets, as previously noted,
began at MacGill University in 1960 with Mordell and Swithenbank. Almost simultaneouslyously, Molder
and his associates at McGill began parallel efforts in hypersonic inlet aerodynamics and gun launched
scrajet flight testing. The inlet work began In the early 1960's and centered around the design
of Buseman-type inlets which were inverted to produce modular inlets with very good performance
characteristics and low external cowl drag and heating. These novel designs also alleviated starting
problems of high area contraction ratio, high design Mach number inlets at low flight Mach numbers,
A number were designed and successfully tested over a wide range of Mach numbers ... .

Gun launching scramjets concepts, a novel idea at the time, began in 1960, evolved to actual
construction in 1966 (supported by the Canadian Defense Research Board) and a horizontal flight test
took place out of a 40.6-cm (16-in.) dia gun in 1968 using triethylaluminum fuel. Unfortunately, the
test was unsuccessful, the structure of the engine failing during launch. Another gun launching
program, however, was begun in the early 1970's, jointly supported by the National Research Council
(Can) and U.S. Army Ballistics Research Lab. In the Spring of 1974, another firing was attempted, this
time at a near vertical (85deg) flight angle at a test range on Barbados. This time, the sabot did not
fully separate, damaging the control surfaces, resulting in an uncontrolled tumbling flight.
Photographs of the engine before and after flight, and of the test range are shown in Fig. 9, While not
completely successful, these are the only reported attempts to actually flight test a scramjet.


I'm trying to locate better pictures of these scramjet test articles that were launched from
project HARP's famous 16 inch naval rifles.

Airrocket, What was (ICF)A and (ICF)B ?

Thanks Again !

 

[DSE]

... Sannu Molder (Canada) who worked with Billig is "the man" in my book when it comes to inward inlets. Molder came up with (ICF) A and (ICF)B. ...

Sorry airrocket for being so late on sending a thanks to you for this post.

I didn't know who Sannu Molder was until I started reading some ramjet/scramjet histories.

One issue with Molder's and the other streamline traced designs of the time is that these inviscid designs had no BL correction. Hence ending up with contraction or pressure ratios far above their design values when tested. That was one of the additions to the procedure which M. Smart brought into the design process used for the REST type inlets.

 

[shockonlip]

... Sannu Molder (Canada) who worked with Billig is "the man" in my book when it comes to inward inlets. Molder came up with (ICF) A and (ICF)B. ...

Sorry airrocket for being so late on sending a thanks to you for this post.

I didn't know who Sannu Molder was until I started reading some ramjet/scramjet histories.

One issue with Molder's and the other streamline traced designs of the time is that these inviscid designs had no BL correction. Hence ending up with contraction or pressure ratios far above their design values when tested. That was one of the additions to the procedure which M. Smart brought into the design process used for the REST type inlets.

Hi DSE.

DSE, it is not true that Molder's designs were not BL corrected.
They were !

I suspected as much and so I checked. I have been in contact
with Sannu Molder for the past 2-3 days.

His response follows:
"Of course the intakes were bl corrected and tested. If there
was anything that worked on these vehicles, it was the intakes.
Their performance was measured, a lot of wind tunnel time was
spent."

He also reminded me that I need to remember the conditions at
launch of these vehicles, namely: sea level and muzzle velocity
of Mach 5.5 ! So quite a Reynolds number to viscous optimize !

So these HARP flights were the first attempt to fly a scramjet
engine! That statement is from the history I quoted earlier
written by the late Paul Waltrup of JHAPL.

Sannu also was kind enough to provide photos of some of this
Martlet II scramjet vehicle work from the HARP project and allow
me to post them. Due to the significance of them, I am going
to open a new topic for them as some people who may be interested
may not care so much about our conversation on inward turning.
I'll do that tonight.

As always DSE, regards!

 

[DSE]

DSE, it is not true that Molder's designs were not BL corrected.
They were !

I suspected as much and so I checked. I have been in contact
with Sannu Molder for the past 2-3 days.

His response follows:
"Of course the intakes were bl corrected and tested. If there
was anything that worked on these vehicles, it was the intakes.
Their performance was measured, a lot of wind tunnel time was
spent."

He also reminded me that I need to remember the conditions at
launch of these vehicles, namely: sea level and muzzle velocity
of Mach 5.5 ! So quite a Reynolds number to viscous optimize !

So these HARP flights were the first attempt to fly a scramjet
engine! That statement is from the history I quoted earlier
written by the late Paul Waltrup of JHAPL.

Sannu also was kind enough to provide photos of some of this
Martlet II scramjet vehicle work from the HARP project and allow
me to post them. Due to the significance of them, I am going
to open a new topic for them as some people who may be interested
may not care so much about our conversation on inward turning.
I'll do that tonight.

Not sure what I thought I was remembering now. I'll have to make a note to pull papers out when I get a chance next week and figure out where I went wrong. I remember a briefing by some army folks who were possibly interested in a scramjet powered tank round. I was thoroughly impressed with the dynamic pressure associated with Mach 8 on the deck. At least you have a nice high Re to deal with compared to the 1-3kpsf trajectories normally used.

Looking forward to the new thread.

 

[DSE]

Still trying to figure out where I went astray, but paper reviews are usurping my time at the moment.

I did find this added presentation about the DOE investigation of these inlets on the NASA site.

http://hapb-www.larc.nasa.gov/Public/Documents/tn-09-542.pdf

 

[shockonlip]

...
I remember a briefing by some army folks who were possibly interested in a
scramjet powered tank round. ...

Maybe you can't say, but was it this attached image (from AIAA-2006-7927 - U.S. Army Hypersonic Scramjet Propelled
Missile Technology Program) ?

 

[DSE]

...
I remember a briefing by some army folks who were possibly interested in a
scramjet powered tank round. ...

Maybe you can't say, but was it this attached image (from AIAA-2006-7927 - U.S. Army Hypersonic Scramjet Propelled
Missile Technology Program) ?

No, these where the real tank guys. Thankfully, nothing to do with that Redstone group. Which also btw put out AIAA 2006-8037, Computational Modeling Advances Supporting Hypersonic Scramjet Design, at the same conference as your ref.

 

[DSE]

Still trying to figure out where I went astray, but paper reviews are usurping my time at the moment.

Finally had some time to go back to the ref and I definitely was mixed up w.r.t Moelder. From Modular Hypersonic Inlets with Conical Inflow, by Moelder and Romeskie, 1968, Figure 7 clearly show the BL correction data.

 

[shockonlip]

Thanks DSE, I can't find that paper, bummer !

That must be the Mach 8 gun tunnell work that Sannu told me about
when we discussed the BL corrections.

 

[DSE]

Thanks DSE, I can't find that paper, bummer !

That must be the Mach 8 gun tunnell work that Sannu told me about
when we discussed the BL corrections.

It's part of AGARD CP-30, which I don't believe is available online through the NATO RTO server or elsewhere.

 

[airrocket]

Great to see Busemann inlet interest. I do not see any great effort of funding required to advanced inward let design in the USA at this time. After FALCON was slammed by the housing recession it seems to have vaporized. Except the Aussie still appear to be funding its advancement. Perhaps AJ at Astrox is still pursuit of DOD funding. Sannu would have worked closely with Billig in the past. There was some rift that developed between Billig and AJ Kotari now of Astrox at some point in the past. My understanding is the rift may stemmed from taking credit for developments. If your talking to Molder then you have sourced the best that I am aware of today my impression is Molder can make them work. I think AJ may stretch the inward benefits a bit however he seems to still be in the game.

 

[airrocket]

My interest of late has shifted more towards the FDL7 SW deeply cooled rocket with the retractable inward inlet. It is a very unique design in the way it varies capture area and short inlet flow path. The RPV model is on my work bench at this time. Powered by SF ducted rocket. I like the FDL-7 inlet as it is retractable to reduce drag and clean-up the lower fuselage for glide and re-entry. Been awhile since I contacted Sannu if you a recent contact email PM me. Great Thread keep it going!!!!!

Regards,

 

[shockonlip]

Great to see Busemann inlet interest. I do not see any great effort of funding required to advanced inward let design in the USA at this time. After FALCON was slammed by the housing recession it seems to have vaporized. Except the Aussie still appear to be funding its advancement. Perhaps AJ at Astrox is still pursuit of DOD funding. Sannu would have worked closely with Billig in the past. There was some rift that developed between Billig and AJ Kotari now of Astrox at some point in the past. My understanding is the rift may stemmed from taking credit for developments. If your talking to Molder then you have sourced the best that I am aware of today my impression is Molder can make them work. I think AJ may stretch the inward benefits a bit however he seems to still be in the game.

Yes Sannu indicated that Fred and others at JH-APL were very supportive of their work on HARP
and other projects.

Yes, I have no doubt that Sannu could make them work. I think the HARP inlets would work. They
were well tested. But they needed 15 or more firings to finish developing the scramjet/sabot
combination. Again its funding.

 

[DSE]

3-D inlet work continues to be funded by both the AFRL Robust Scramjet and NASA Fundamental Astronautics Hypersonic Projects. It looks like all the DARPA airbreathing propulsion programs have bit the dust. I see some of the collaborative NASA/Aussie work is supposed to be presented at the Aerospace Planes Conference by looking at the published program. The issues with these inlets isn't on-design, but off-design operation and performance. Also much more difficult to fabricate (ie costly), unless one is talking about SLS for cold flow testing or NC cut plastiform which is OK in shock tunnels. Articles for longer true enthalpy engine tests are still more costly. If one then takes the next ultimate step to fuel cooled hardware then it becomes much more difficult and costly by today's methods.

 

[airrocket]

2D is more straight forward, easier to analysis and less costly than 3D when developing a new advance body integrated propulsion system. NASA was very keen on 3D inward inlet research prior to 2003/2004 "back to the moon". At that point in time research focus and funds shifted towards deep space rather than LEO. Now that DARPA has pulled back from 3D inlet tech China and the Aussie's are at the forefront with perhaps Astrox still hangng on to DOD funding. And NASA still has some skin in the game however funding and focus these days is trivial to what is required to bring such a technology into real world full scale application. Perhaps a commercial company could do small scale development however few if any of them embrace propulsion tech beyond basic rocket. Certainly the Aussies could benefit from such technology for suborbital point to point transport. Being somewhat isolated way down-under if funding was available the Aussies would have the justification to put it to use. However again funding is far from what is required to transition from small scale R&D to full-scale real world applications. I for one certainly hope enough interest and funding remains to maintain 3D inlet tech awareness into the future.

 

[DSE]

2D is more straight forward, easier to analysis and less costly than 3D when developing a new advance body integrated propulsion system. NASA was very keen on 3D inward inlet research prior to 2003/2004 "back to the moon". At that point in time research focus and funds shifted towards deep space rather than LEO. Now that DARPA has pulled back from 3D inlet tech China and the Aussie's are at the forefront with perhaps Astrox still hangng on to DOD funding. And NASA still has some skin in the game however funding and focus these days is trivial to what is required to bring such a technology into real world full scale application. Perhaps a commercial company could do small scale development however few if any of them embrace propulsion tech beyond basic rocket. Certainly the Aussies could benefit from such technology for suborbital point to point transport. Being somewhat isolated way down-under if funding was available the Aussies would have the justification to put it to use. However again funding is far from what is required to transition from small scale R&D to full-scale real world applications. I for one certainly hope enough interest and funding remains to maintain 3D inlet tech awareness into the future.

Actually, under the NASA FAP Hypersonics project 3-D inlet design has been one of few funded major activities. It is part of a longer term effort in 3-D high fidelity MDAO for the full vehicle, which is both part of the hypersonic propulsion and MDAO subject areas. The following paper on this work is to be presented at the AIAA Space Planes Conference, Investigation of REST class Hypersonic Inlet Designs, R. Gollan, National Institute of Aerospace, Hampton, VA; P. Ferlemann, NASA Langley Research Center, Hampton, VA. See p 27 of http://www.aeronautics.nasa.gov/fap/2009_FAP_Hyp_Overview_Pittman.pdf for the 3-D Configuration line inclusion in the program.

2011 AIAA Space Planes program
http://aiaa-mhytasp11.abstractcentral.com/societyimages/aiaa-mhytasp11/AIAA-MHYTASP11_Program_Matrix_march21.pdf

 

[shockonlip]

My interest of late has shifted more towards the FDL7 SW deeply cooled rocket with the retractable inward inlet. It is a very unique design in the way it varies capture area and short inlet flow path. The RPV model is on my work bench at this time. Powered by SF ducted rocket. I like the FDL-7 inlet as it is retractable to reduce drag and clean-up the lower fuselage for glide and re-entry. Been awhile since I contacted Sannu if you a recent contact email PM me. Great Thread keep it going!!!!!

Regards,

As far as FDL7 based vehicle is concerned, something like this?

 

[shockonlip]

3-D inlet work continues to be funded by both the AFRL Robust Scramjet and NASA Fundamental Astronautics Hypersonic Projects. It looks like all the DARPA airbreathing propulsion programs have bit the dust. I see some of the collaborative NASA/Aussie work is supposed to be presented at the Aerospace Planes Conference by looking at the published program. The issues with these inlets isn't on-design, but off-design operation and performance. Also much more difficult to fabricate (ie costly), unless one is talking about SLS for cold flow testing or NC cut plastiform which is OK in shock tunnels. Articles for longer true enthalpy engine tests are still more costly. If one then takes the next ultimate step to fuel cooled hardware then it becomes much more difficult and costly by today's methods.

Just out of curiosity, how much we talking for fuel cooled hardware?
Any idea?

 

[DSE]

3-D inlet work continues to be funded by both the AFRL Robust Scramjet and NASA Fundamental Astronautics Hypersonic Projects. It looks like all the DARPA airbreathing propulsion programs have bit the dust. I see some of the collaborative NASA/Aussie work is supposed to be presented at the Aerospace Planes Conference by looking at the published program. The issues with these inlets isn't on-design, but off-design operation and performance. Also much more difficult to fabricate (ie costly), unless one is talking about SLS for cold flow testing or NC cut plastiform which is OK in shock tunnels. Articles for longer true enthalpy engine tests are still more costly. If one then takes the next ultimate step to fuel cooled hardware then it becomes much more difficult and costly by today's methods.

Just out of curiosity, how much we talking for fuel cooled hardware?
Any idea?

I don't believe there really has been much credible work in regard to this. No hardware of this type has been built to my knowledge. I have seen estimates by one of the major propulsion houses that put it something around two orders of magnitude above 2-D hardware. But this is an area that really hasn't been tackled yet and I believe its going take take folks actually trying to do this to make real progress. Several efforts at lower temperature uncooled inlets using sintered rapid prototyping processes have been less than successful.

 

[RanulfC]

My interest of late has shifted more towards the FDL7 SW deeply cooled rocket with the retractable inward inlet. It is a very unique design in the way it varies capture area and short inlet flow path. The RPV model is on my work bench at this time. Powered by SF ducted rocket. I like the FDL-7 inlet as it is retractable to reduce drag and clean-up the lower fuselage for glide and re-entry. Been awhile since I contacted Sannu if you a recent contact email PM me. Great Thread keep it going!!!!!

Regards,

As far as FDL7 based vehicle is concerned, something like this?

Interesting concept SOL, but I'm trying to get a mental picture of how you'd do a 'drop-down' inward-turning?

Randy

 

[shockonlip]

My interest of late has shifted more towards the FDL7 SW deeply cooled rocket with the retractable inward inlet. It is a very unique design in the way it varies capture area and short inlet flow path. The RPV model is on my work bench at this time. Powered by SF ducted rocket. I like the FDL-7 inlet as it is retractable to reduce drag and clean-up the lower fuselage for glide and re-entry. Been awhile since I contacted Sannu if you a recent contact email PM me. Great Thread keep it going!!!!!

Regards,

As far as FDL7 based vehicle is concerned, something like this?

Interesting concept SOL, but I'm trying to get a mental picture of how you'd do a 'drop-down' inward-turning?

Randy

HA! At first I didn't know who SOL was !!

So I ran across this design drawing in a technical paper I looked at during the weekend.
It immediately reminded me of airrocket's earlier post. He's the one that is more up
on it than I, but I jotted down some ideas below.

So the first thing, assuming that the inlet worked in a certain Mach number range when it
was lowered. And the FDL-7's boundary layer was handled, etc.

There would be two aspects:
1. On ascent, retracting the inlet once you were no longer breathing air.
2. On descent, perhaps you want to lower the inlet to breath air (assuming you have
fuel remaining to do that). You may not need to lower the inlet if you have adequate
cross-range from gliding flight alone due to the reduced drag of the inlet being
retracted. That is a key point, and could be one of the main reasons the inlet is to
be retracted, namely cross-range on reentry.

For raising the inlet, there is the transient flow conditions (but I would suspect that
raising a inward turning inlet is like a fixed inward turning inlet, at a nonzero and varying
angle of attack - all inlets have to handle that - within limits of course), and the loads on
the mechanism that raises the inlet, and temperature issues caused by the flow, and the seals
to close off the inlet when it was raised. Also perhaps handling the heat of the inlet when it
is up inside the vehicle. I'm sure there are other aspects as well.

For lowering the inlet, there are transient flow conditions, and the loads, temperature issues,
and getting the inlet started, but then you can control at what Mach numbers you lower it.

So I'm not sure what aspect of this you are having a hard time visualizing.

Even a fixed inward turning inlet has to deal with off-axis flow (yaw, pitch, roll), within
certain limits of course. Outside those limits, the inlet isn't expected to function well.
The inward turning is a function of the inlet alone. There is no fuselage impact here,
except for the fuselage boundary layer, which does have to be dealt with, but I weaived
my hands in the air earlier saying I assumed we dealt with that in the design of the inlet
when it was lowered.

There are the nasty shock/boundary layer interactions we have to be careful of, but we'd
look at that stuff when we designed the inlet.

Maybe it would be a lot harder than we thought.

Did you want to explore these above kinds of issues, or were you thinking of something else?

 

[RanulfC]

Interesting concept SOL, but I'm trying to get a mental picture of how you'd do a 'drop-down' inward-turning?

Randy

HA! At first I didn't know who SOL was !!

I kept typing "shockonlip" but it never "looked" right.. Probably a surpressed memory of what kind of trouble I got into when I typed in "Full Thrust" (a minatures space ship combat game) into the "search" function on a government computer

So I'm not sure what aspect of this you are having a hard time visualizing.

In the main it's because I have limited visuals on "inward-turning" inlets that are not based on those from ASTEROX and look like a "C" turned on it's side.

Did you want to explore these above kinds of issues, or were you thinking of something else?

In general yes to all the above AND anything else since I'm interested in the whole concept and how/why it works the way it does and what are the various types and methods.

I was introduced and looked at the various information surrounding the "C" (Asterox) type inlets first and then types like that suggested for the BlackSwift and while I could grasp the majority of the former the latter seemed to be fundamentally different and not as intiative I guess.

Information and explanations are always in demand

Randy

 

[shockonlip]

Randy, do you want to understand all the design details including the
math or do you just want to understand what is going on from a picture
concept standpoint?

Here's an approach I used and am using with the learn the details approach:
1. I am interested in Busemann inlets.
2. First, I made sure I understand John Anderson's "Modern Compressible Flow"
chapter on Taylor-Maccoll derivation (conical flow) because the algorithm
to generate such inlets uses Taylor-Maccoll. I'm talking about understanding
Anderson's derivation of the Taylor-Maccoll equation itself. He also has
a computer algorithm for computing cone flow with Taylor-Maccoll in that chapter.
The actual Busemann inlet procedure (below) begins with the Taylor-Maccoll
equation. You may have to play with some algebra to get the equation to exactly
match with 3 (below).
3. Get a good description of the Busemann inlet generation algorithm like
the one written by Sannu Molder and Dave Van Wie available through the
AIAA (note - this algorithm is taught in some of the hypersonic classes
taught to aerospace professionals) - AlAA 92-1210 - "Applications
of Busemann Inlet Designs for Flight at Hypersonic Speeds". If you need
help ordering this, I can show you how to do that. PM me.
4. Play with it and then read some of the other inward turning papers, like
stremline tracing and others. There is actually quite a few.

DSE may have some better ideas on how to boot yourself on this stuff.
I'd actually like to hear his comments myself.

The above is how I started. I had to work at it, but I finally got through it.
I actually rather enjoy it now. I have to go off and do more.

Maybe we should collect a list of papers.

Other inlets like 2-D and 3-D inlets have their own literature as well. It's a
complete field actually.

 

[DSE]

One point to keep in mind is that while a Busemann is an inward turning inlet, all inward turning inlet need not be Busemanns. The Busemann uses a conically symmetric isentropic compression field. However, there is no requirement that this be the starting flowfield. One can streamline trace any compression field they want. The Busemann is just one easy way to mathematically do this. If you look at the REST work at NASA and now UQ a different compression field is used which is generated by a conical supersonic diffuser with a centerbody, which is another relatively easy way of mathematically generating a compression field. Note, this is not a conically symmetric flowfield like the Busemann. Once you have a given compression field it is a matter of tracing streamlines in that flowfield, unless one then takes a morphing/lofting approach to introduce a shape transition or add a BL correction or some otherwise modify the shape.

Note edited/added text in bold.

 

[airrocket]

Fuel cooled as in LACE or Deeply cooled rocket. Rudakov, Balepin in Russia then Japan with Baraban now the SABRE research. JAXA did build and fly a sub-scale RC based model with per-cooler in the inlet. I think it was mach plus capable still a long way from a flight ready M5 version.

http://ftp.rta.nato.int/public//PubFullText/RTO/EN/RTO-EN-AVT-150///EN-AVT-150-02.pdf


The inward inlet I reference is the one depicted in the FDL-7 sketch per shockonlip. As DSE mentioned "inward turning" can include many concepts. The streamlined trace "sugar scoop bleed" inlets DARPA Steve Walker Blackshift type are the latest resurgence of the concept I'm aware of.

http://www.freepatentsonline.com/20070187550.pdf

The Aussie's Queensland R&D seem to sport many versions and concepts which utilize the "sugar scoop" inlet lip style. Astrox sports several lifting body conceptual planforms with the sugar scoop lip. And I seem to recall that AJ Kothari was working on sub-scale prootype AFRL backed.

Looking to the future, an innovative airbreathing
vehicle concept was designed by
Astrox, ASC/XR, AFRL, and Boeing to be
the reusable second stage of a two-stage-toorbit
launch system boosted by a reusable
rocket first stage. The second stage is powered
by rocket-based combined-cycle (RBCC)
engines fueled by methane and LOX/hydrogen.
The vehicle has innovative design features
such as twin 3D inward-turning inlet
flow paths and engines mounted on the vehicle
upper surface to shield them from dense,
high-temperature air during atmospheric entry.
These features enable the vehicle to avoid
the engine thermal protection and/or management
challenges normally present during
by E. Russ Althof unpowered flight.


http://nextbigfuture.com/2010/08/astrox-hypersonic-vehicle-designs-and.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+blogspot%2Fadvancednano+(nextbigfuture)

DSE link to current R&D is encouraging....thanks for that DSE.

My FDL-7 RV sub-scale model now under construction with the inward retractable design inlet is solid fuel (rich burning) augmented rocket. Its CRuSR based inspired design. As you can see I'm still playing with spiked inlets/ducted rockets. That is proto test rocket of the FDL-7 model augmented propulsion.

 

[airrocket]

Worked with Paul C. on FDL-7 concept with over/under inward sugar scoop inlets..."HyHAWK". Over under sounds similar to AJ's AFRL concept as the stream traced inlet lips "sugar scoop" located each side of upper fuse (chine location) and the exhaust located under body (over/under) twisting Sannu's sugar scoop design 180 degrees at the front. Idea was to reduce re-entry and glide drag heating issues and balance inlet induced pitch of 2D under body inlets/exhaust propulsion. I approached AJ at Astrox years back with the over/under sub-scale lifting body concept. That is when I also hooked up with Paul C. and became FDL-7 aware. AJ's and Astrox lifting bodies just did not seem to fit the planform I was looking for. However AJ had the funds. The search for lifting body tech lead me to Paul C. who directed me to Sannu for the inward compression inlet tech. I sensed Paul was not really all that much for the inward inlet over/under concept. Paul felt it gave up to much compression lift that 2D underbody inlet designs generate. And that AJ perhaps overstated the 3D inlet benefits. Anyway I went forward with it and the whole thing faded away with DARPA R&D inward demise. MEMS sensor were to be employed for data gathering in the inlets and MEMS actuators attached to the fuse to test morphing shapes on the exterior of the sub-scale M4 model to effect supersonic shock wave formation and effect pitch/yaw motions. Propulsion was solid ducted rocket at first then was investigating Orbitec Vortex Hybrid towards the end utilized in a RamRocket configuration. And the model keep getting larger in size. Anyway now I have a large file of FDL-7 and FDL-5 lifting body data along with 3D compression inward inlet tech. Now what to do with it.....CRuSR?

 

[DSE]

Looking to the future, an innovative airbreathing
vehicle concept was designed by
Astrox, ASC/XR, AFRL, and Boeing to be
the reusable second stage of a two-stage-toorbit
launch system boosted by a reusable
rocket first stage. The second stage is powered
by rocket-based combined-cycle (RBCC)
engines fueled by methane and LOX/hydrogen.
The vehicle has innovative design features
such as twin 3D inward-turning inlet
flow paths and engines mounted on the vehicle
upper surface to shield them from dense,
high-temperature air during atmospheric entry.
These features enable the vehicle to avoid
the engine thermal protection and/or management
challenges normally present during
by E. Russ Althof unpowered flight.

Note in some of what I pointed to NASA was doing/has done a performance evaluation of the Astrox AFRL RBCC TSTO "design."

 

[shockonlip]

...

Note in some of what I pointed to NASA was doing/has done a performance evaluation of the Astrox AFRL RBCC TSTO "design."

In the 2011 Spaceplanes Conference Agenda?

The following one?

Investigation of REST class Hypersonic Inlet Designs
R. Gollan,
National Institute of Aerospace,
Hampton, VA;
P. Ferlemann,
NASA Langley Research Center,
Hampton, VA

 

[shockonlip]

Fuel cooled as in LACE or Deeply cooled rocket. ...

My FDL-7 RV sub-scale model now under construction with the inward retractable design inlet is solid fuel (rich burning) augmented rocket. Its CRuSR based inspired design. As you can see I'm still playing with spiked inlets/ducted rockets. That is proto test rocket of the FDL-7 model augmented propulsion.

Neat!

What's the solid engine - "high power" engines, through the high power rocketry groups?

Or do you have solid rocket engines constructed for you from one of the vendors?

Hobby or professional?

Sorry if I'm being too pushey.

I'm trying to figure out how to do some of this myself.

It's good to see an airbreathing guy out there.

How do you instrument your airbreathers to test them ?
Maybe we should email as I have more questions.