Inward-turning Inlets

shockonlip yes email me...website is still valid although badly in need of an update. I sort of dropped out of the hobby stuff and went more commercial for awhile and website is more of a contact portal at this time.

I became aware a renewed interest in 3D compression inward inlet stuff in the late 1990's. A comment from a failed NASA SBIR 2D inlet based concept proposal reviewer tipped me off. The reviewer stated that 2D inlet tech was not of interest at the time due to recent hyper 3D inward inlet developments. I'm always looking for a tip in reports, comments etc... (secret projects always been in my blood) and that set off whole series of unique discoveries and events for me. And ultimately lead me to contact Paul C. which set off another series of discoveries....

I use a combo of hobby HP, commercial and home brew motors. HP is good for up to around M2 after that the cost an motor size becomes a limiting factor and you need go commercial based with "FUNDING" unless you have very deep pockets. Many of the small business companies that serve the HP hobby market also do commercial, military stuff and often have hardware and propellant grains left over from those projects at reduced cost. Also much of micro turbine hobby motors can be combined with automotive based turbocharger components to yield ATR hardware. I'm an integrator more than an inventor I like to fly hardware not much of a lab rat.

airrocket said:

shockonlip yes email me...website is still valid although badly in need of an update. I sort of dropped out of the hobby stuff and went more commercial for awhile and website is more of a contact portal at this time.

I became aware a renewed interest in 3D compression inward inlet stuff in the late 1990's. A comment from a failed NASA SBIR 2D inlet based concept proposal reviewer tipped me off. The reviewer stated that 2D inlet tech was not of interest at the time due to recent hyper 3D inward inlet developments. I'm always looking for a tip in reports, comments etc... (secret projects always been in my blood) and that set off whole series of unique discoveries and events for me. And ultimately lead me to contact Paul C. which set off another series of discoveries....

I use a combo of hobby HP, commercial and home brew motors. HP is good for up to around M2 after that the cost an motor size becomes a limiting factor and you need go commercial based with "FUNDING" unless you have very deep pockets. Many of the small business companies that serve the HP hobby market also do commercial, military stuff and often have hardware and propellant grains left over from those projects at reduced cost. Also much of micro turbine hobby motors can be combined with automotive based turbocharger components to yield ATR hardware. I'm an integrator more than an inventor I like to fly hardware not much of a lab rat.

Click to expand...

There are groups out there in the HP rocket community that do custom motors. For example the S motor for the Go Fast launch was done by a private group IIRC. I've seen several P's and Q's done by private individuals as well.

shockonlip said:

DSE said:

airrocket said:

...

Click to expand...

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

Click to expand...

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

Click to expand...

No that's just some recent progress on a subset of the 3-D inlet design tools. It was a higher level FAP MDAO chart that just mentioned it. The results probably will never be made public. See p. 22 of http://www.aeronautics.nasa.gov/fap/2009_FAP_Hyp_Overview_Pittman.pdf

Variable Inward Inlet as used on FDL-7 SW.

Interesting!

Interesting how the contraction changes too !

A good resource for comparing bleed slot and "sugar scoop slit" intake designs and how they effect inlet start, shock positionong and spillage.

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA438398

Thanks airrocket !

airrocket said:

A good resource for comparing bleed slot and "sugar scoop slit" intake designs and how they effect inlet start, shock positionong and spillage.

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA438398

Click to expand...

I hope you are joking, this is quite a disturbing document. It is useful only as a counter-intelligence resource. That this passed for a master's thesis at AFIT is quite sad. This must be one of the most convoluted, non-physical interpretation and implementation of the "Kantrowitz Limit" applied to the super/hypersonic inlet starting problem I have ever seen in all my years. It also shows an ignorance or maybe arrogance of some attracted to so-called inward-turning inlet technology that there is little or nothing to be learned from the last 30 years of 3-D inlet work, just because it wasn't specifically using inward-turning designs. It also draws a completely erroneous general conclusion to the work of Dr. Smart in the cited reference.

Shockonlip,

Be sure to check the Bibliography and "Resources" section of the pdf I posted as well as the others listed here. Often times there are leads in them to direct you to more specific information. Myself I am looking for supersonic m4-5 max rather than hyper inward inlet applications. Beyond M3-4 the hyper realm and SCRAM technology is way out there materials, software etc..... And years away from actual applications. There exist a wealth of NACA late forties/fifties ram inlet tech and NASA 60's on inward inlet reports that are dated however the designs, materials and hardware do work and are good up to M2.5 and perhaps beyond into the M3 realm. The old NACA reports contain detailed drawings and explanations that a novice can grasp without getting a headache in the process. While many of the recent studies go in depth into the design and shape of the inward inlet I found few that reference the actual functional details of the slit or scoop and bleeds in depth. This is an area I would like to obtain more information and understanding of.

Any information in those regards I would like to see more of.

DSE said:

airrocket said:

A good resource for comparing bleed slot and "sugar scoop slit" intake designs and how they effect inlet start, shock positionong and spillage.

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA438398

Click to expand...

I hope you are joking, this is quite a disturbing document. It is useful only as a counter-intelligence resource. That this passed for a master's thesis at AFIT is quite sad. This must be one of the most convoluted, non-physical interpretation and implementation of the "Kantrowitz Limit" applied to the super/hypersonic inlet starting problem I have ever seen in all my years. It also shows an ignorance or maybe arrogance of some attracted to so-called inward-turning inlet technology that there is little or nothing to be learned from the last 30 years of 3-D inlet work, just because it wasn't specifically using inward-turning designs. It also draws a completely erroneous general conclusion to the work of Dr. Smart in the cited reference.

Click to expand...

I'll be sure to keep your input in mind when I read this.
Thanks.

airrocket said:

Shockonlip,

Be sure to check the Bibliography and "Resources" section of the pdf I posted as well as the others listed here. Often times there are leads in them to direct you to more specific information. Myself I am looking for supersonic m4-5 max rather than hyper inward inlet applications. Beyond M3-4 the hyper realm and SCRAM technology is way out there materials, software etc..... And years away from actual applications. There exist a wealth of NACA late forties/fifties ram inlet tech and NASA 60's on inward inlet reports that are dated however the designs, materials and hardware do work and are good up to M2.5 and perhaps beyond into the M3 realm. The old NACA reports contain detailed drawings and explanations that a novice can grasp without getting a headache in the process. While many of the recent studies go in depth into the design and shape of the inward inlet I found few that reference the actual functional details of the slit or scoop and bleeds in depth. This is an area I would like to obtain more information and understanding of.

Any information in those regards I would like to see more of.

Click to expand...

Yes, I'll check nthe refs. Thanks.
I don't know that I agree that the hyper realm and SCRAM tech is way out there. I think
the tech is understandable. Maybe the implementation is not for mere mortals like us. But
if we used the hot rodder mentality, ... .
But I ran across a paper on a $2000 shock tunnel last night, which I haven't read yet. I am
interested in how one could do scram on the cheap. Maybe getting a ride on a sounding rocket
like the Aussies. Don't know. I need to evaluate the costs. Just getting started.
Maybe get a loan and buy the parts and finish RHYFL and rent it out! OK that's crazy.

shockonlip said:

I don't know that I agree that the hyper realm and SCRAM tech is way out there. I think
the tech is understandable. Maybe the implementation is not for mere mortals like us. But
if we used the hot rodder mentality, ... .
But I ran across a paper on a $2000 shock tunnel last night, which I haven't read yet. I am
interested in how one could do scram on the cheap. Maybe getting a ride on a sounding rocket
like the Aussies. Don't know. I need to evaluate the costs. Just getting started.
Maybe get a loan and buy the parts and finish RHYFL and rent it out! OK that's crazy.

Click to expand...

For tests on the cheap in the use at low Mach you might consider trying to hook up with Karl Hoose at ATS up in Maine.
http://www.appliedthermalsciences.com/blog/ATSVB0001.html

Hypersonic - White Paper - Low Cost Ramjet/Scramjet Flight Testing for Time Critical Strike Weapons Development http://www.appliedthermalsciences.com/documents/download.php?yourfile=LowCostRamjetFlightTesting-WhitePaper.pdf

You must have one heck of a credit rating to even joke about RHYFL.

airrocket said:

Shockonlip,

Be sure to check the Bibliography and "Resources" section of the pdf I posted as well as the others listed here. Often times there are leads in them to direct you to more specific information. Myself I am looking for supersonic m4-5 max rather than hyper inward inlet applications. Beyond M3-4 the hyper realm and SCRAM technology is way out there materials, software etc..... And years away from actual applications. There exist a wealth of NACA late forties/fifties ram inlet tech and NASA 60's on inward inlet reports that are dated however the designs, materials and hardware do work and are good up to M2.5 and perhaps beyond into the M3 realm. The old NACA reports contain detailed drawings and explanations that a novice can grasp without getting a headache in the process. While many of the recent studies go in depth into the design and shape of the inward inlet I found few that reference the actual functional details of the slit or scoop and bleeds in depth. This is an area I would like to obtain more information and understanding of.

Any information in those regards I would like to see more of.

Click to expand...

A good place to start is the AIAA Education Series: Practical Intake Aerodynamic Design and Intake Aerodynamics both by Seddon and Goldsmith

DSE said:

Hypersonic - White Paper - Low Cost Ramjet/Scramjet Flight Testing for Time Critical Strike Weapons Development http://www.appliedthermalsciences.com/documents/download.php?yourfile=LowCostRamjetFlightTesting-WhitePaper.pdf

Click to expand...

Interesting paper, one program objective, "the quick acceleration from M1.3 to M5" would make for a heck of a HDBT (hard and deeply buried target) strike weapon. Could arrive over the target in roughly half the time of a cruise missile, lock onto the target before accelerating. As the paper says easier on the material but might make the sensor simpler - it would strike the target so fast after locking on it might not matter if the sensor was "blinded" by the heat from the acceleration (stationary target of course).

DSE said:

airrocket said:

Shockonlip,

Be sure to check the Bibliography and "Resources" section of the pdf I posted as well as the others listed here. Often times there are leads in them to direct you to more specific information. Myself I am looking for supersonic m4-5 max rather than hyper inward inlet applications. Beyond M3-4 the hyper realm and SCRAM technology is way out there materials, software etc..... And years away from actual applications. There exist a wealth of NACA late forties/fifties ram inlet tech and NASA 60's on inward inlet reports that are dated however the designs, materials and hardware do work and are good up to M2.5 and perhaps beyond into the M3 realm. The old NACA reports contain detailed drawings and explanations that a novice can grasp without getting a headache in the process. While many of the recent studies go in depth into the design and shape of the inward inlet I found few that reference the actual functional details of the slit or scoop and bleeds in depth. This is an area I would like to obtain more information and understanding of.

Any information in those regards I would like to see more of.

Click to expand...

A good place to start is the AIAA Education Series: Practical Intake Aerodynamic Design and Intake Aerodynamics both by Seddon and Goldsmith

Click to expand...

I completely agree.

I have both and have read much of both of them.
Very Good!

I also suggest the AIAA book:
"Inlets for Supersonic Missiles"
John J. Mahoney
AIAA Education Series
Published by AIAA, © 1991, 237 pages, Hardback
ISBN-10: 0-930403-79-7
ISBN-13: 978-0-930403-79-9

John Mahoney was a inlet specialist at Marquardt.

I REALLY recommend his SAE Paper entitled:

"Inlet Diffuser Design Techniques"
J.J. Mahoney
The Marquardt Corporation
1962

The above is one of the finest intro papers for inlet
design I have ever seen.

If you need help getting it airrocket, let me know.

shockonlip said:

[
I also suggest the AIAA book:
"Inlets for Supersonic Missiles"
John J. Mahoney
AIAA Education Series
Published by AIAA, © 1991, 237 pages, Hardback
ISBN-10: 0-930403-79-7
ISBN-13: 978-0-930403-79-9

John Mahoney was a inlet specialist at Marquardt.

I REALLY recommend his SAE Paper entitled:

"Inlet Diffuser Design Techniques"
J.J. Mahoney
The Marquardt Corporation
1962

The above is one of the finest intro papers for inlet
design I have ever seen.

If you need help getting it airrocket, let me know.

Click to expand...

I have this book as well just couldn't pull the name from memory and was going to wait until I could look on the bookshelf at work. There is also an old NAVWEPS (sp?) report series that I have the volume governing gas dynamics, inlets/diffusers, combustion and nozzles that I've had since grad school. Another very good reference.

Cronvich, L.L., Faro, I.D.V. Handbook of Supersonic Aerodynamics. Section 17. Ducts, Nozzles and Diffusers. NAVWEPS Report 1488, Vol. 6, January 1964

shockonlip said:

I'll be sure to keep your input in mind when I read this.
Thanks.

Click to expand...

A decent look at the inlet starting problem is given in AIAA-88-3257 Inlet Starting Predictions for Sidewall-Compression Scramjet Inlets by Trexler. The key is having enough total pressure downstream of the unstarted shock to get the required mass flow through the available area(s), so that this shock can be swallowed. It has nothing to do about relieving pressure. Bleed holes and cutouts just provide another possible area for the flow to go, however one must take some basic fluid mechanics into account and allow for real entrance effects (ie discharge coeffs.).

Thank you DSE...I like that clear concise and basic.

Check this out...how to do R&D on smaller budget using HP type hardware.

http://www.appliedthermalsciences.com/blog/ATSVB0026.html

airrocket said:

Thank you DSE...I like that clear concise and basic.

Click to expand...

You're welcome. I'm sorry I came across as I did in the original reply. This thesis just irked me on so many different levels, the most basic that this poor student came away with such a lack of the fundamentals involved in the inlet starting problem. It didn't help that I know a few of those referenced and had/have a hard time comprehending how they might have even been peripherally involved and it still come to this end. Another irritation is the lack of many of those involved in the 3D inlet work these days having not learned the lessons from multi-dimensional internal compression work done by NASA and others, such as Rocketdyne.


Title: Rocket-Based Combined Cycle Engine Concept Development
Online Source: Click to View PDF File [PDF Size: 978 KB]
Author: Ratekin, G.; Goldman, Allen; Ortwerth, P.; Weisberg, S.; McArthur, J. Craig
Abstract:
The development of rocket-based combined cycle (RBCC) propulsion hide hide
systems is part of a 12 year effort under both company funding and contract work. The concept is a fixed geometry integrated rocket, ramjet, scramjet, which is hydrogen fueled and uses hydrogen regenerative cooling. The baseline engine structural configuration uses an integral structure that eliminates panel seals, seal purge gas, and closeout side attachments. Engine A5 is the current configuration for NASA Marshall Space Flight Center (MSFC) for the ART program. Engine A5 models the complete flight engine flowpath of inlet, isolator, airbreathing combustor, and nozzle. High-performance rocket thrusters are integrated into the engine enabling both low speed air-augmented rocket (AAR) and high speed pure rocket operation. Engine A5 was tested in GASL's new Flight Acceleration Simulation Test (FAST) facility in all four operating modes, AAR, RAM, SCRAM, and Rocket. Additionally, transition from AAR to RAM and RAM to SCRAM was also demonstrated. Measured performance demonstrated vision vehicle performance levels for Mach 3 AAR operation and ramjet operation from Mach 3 to 4. SCRAM and rocket mode performance was above predictions. For the first time, testing also demonstrated transition between operating modes.
Collection: NASA
NASA Center: Marshall Space Flight Center
Publication Date: [2001]
Publication Year: 2001
Document ID: 20020016608
Subject Category: SPACECRAFT PROPULSION AND POWER
Contract/Grant/Task Number: NAS8-40864
Publication Information: Number of pages = 35
Language: English
Subject Terms: ENGINE DESIGN; FLIGHT SIMULATION; PERFORMANCE TESTS; PROPULSION SYSTEM CONFIGURATIONS; RAMJET ENGINES; STRUCTURAL ANALYSIS; SUPERSONIC COMBUSTION RAMJET ENGINES; WEIGHT REDUCTION
Accessibility: Unclassified; Publicly available; Unlimited; Copyright, Distribution as joint owner in the copyright
Document Source: CASI
Updated/Added to NTRS: Jul 25, 2009
http://hdl.handle.net/2060/20020016608



Title: A Combined Experimental/Computational Investigation of a Rocket Based Combined Cycle Inlet
Online Source: Click to View PDF File [PDF Size: 1024 KB]
Author: Smart, Michael K.; Trexler, Carl A.; Goldman, Allen L.
Abstract:
A rocket based combined cycle inlet geometry has undergone wind tunnel hide hide
testing and computational analysis with Mach 4 flow at the inlet face. Performance parameters obtained from the wind tunnel tests were the mass capture, the maximum back-pressure, and the self-starting characteristics of the inlet. The CFD analysis supplied a confirmation of the mass capture, the inlet efficiency and the details of the flowfield structure. Physical parameters varied during the test program were cowl geometry, cowl position, body-side bleed magnitude and ingested boundary layer thickness. An optimum configuration was determined for the inlet as a result of this work.
Collection: NASA
NASA Center: Langley Research Center; Marshall Space Flight Center
Publication Date: [2001]
Publication Year: 2001
Document ID: 20010023936
Subject Category: SPACECRAFT PROPULSION AND POWER
Report/Patent Number: AIAA Paper 2001-0671
Publication Information: Number of pages = 10
Language: English
Meeting Information: Aerospace Sciences; 39th; 8-11 Jan. 2001; Reno, NV; United States
Subject Terms: ANALYSIS (MATHEMATICS); COMPUTATIONAL FLUID DYNAMICS; FLOW DISTRIBUTION; PRESSURE; ROCKET-BASED COMBINED-CYCLE ENGINES; SPACECRAFT PROPULSION; SUPERSONIC SPEED; WIND TUNNEL TESTS
Accessibility: Unclassified; Publicly available; Unlimited; Copyright, Distribution as joint owner in the copyright
Document Source: CASI
Updated/Added to NTRS: Jul 25, 2009
http://hdl.handle.net/2060/20010023936

Fixed geometry engine...way cool.

airrocket said:

Fixed geometry engine...way cool.

Click to expand...

The work of P. Ortwerth, G. Ratekin and A. Goldman, now all retired. What's left of the Rocketdyne hypersonics group has been assimilated with the creation of PWR.

One saving grace of these open bottom inlets can be the relatively benign unstarts, due to their low level of internal contraction.

DSE said:

It didn't help that I know a few of those referenced and had/have a hard time comprehending how they might have even been peripherally involved and it still come to this end. Another irritation is the lack of many of those involved in the 3D inlet work these days having not learned the lessons from multi-dimensional internal compression work done by NASA and others, such as Rocketdyne.

Click to expand...

A lot of 'reinventing the wheel' going on at the moment.

Grey Havoc said:

DSE said:

It didn't help that I know a few of those referenced and had/have a hard time comprehending how they might have even been peripherally involved and it still come to this end. Another irritation is the lack of many of those involved in the 3D inlet work these days having not learned the lessons from multi-dimensional internal compression work done by NASA and others, such as Rocketdyne.

Click to expand...

A lot of 'reinventing the wheel' going on at the moment.

Click to expand...

Get use to it. We'll be doing that a LOT in the coming years due mainly to short-sighted pols.

Too true.

DSE said:

shockonlip said:

I'll be sure to keep your input in mind when I read this.
Thanks.

Click to expand...

A decent look at the inlet starting problem is given in AIAA-88-3257 Inlet Starting Predictions for Sidewall-Compression Scramjet Inlets by Trexler. The key is having enough total pressure downstream of the unstarted shock to get the required mass flow through the available area(s), so that this shock can be swallowed. It has nothing to do about relieving pressure. Bleed holes and cutouts just provide another possible area for the flow to go, however one must take some basic fluid mechanics into account and allow for real entrance effects (ie discharge coeffs.).

Click to expand...

Agreed on the main P0 statement, but don't know what you were getting at with
"(ie discharge coeffs.)". By real entrance effects I would think of BL
and maybe other things like alpha (angle of attack).

I decided to get the paper and go through it. I got 1/3 through last night.
I also had to download Kantrowitz, Machkey, and Moeckel, and Dean.

DSE said:

airrocket said:

Fixed geometry engine...way cool.

Click to expand...

The work of P. Ortwerth, G. Ratekin and A. Goldman, now all retired. What's left of the Rocketdyne hypersonics group has been assimilated with the creation of PWR.
One saving grace of these open bottom inlets can be the relatively benign unstarts, due to their low level of internal contraction.

Click to expand...

Another doc with much of the same info and a poster image.

http://ntrs.larc.nasa.gov/?N=0&Ntk=All&Ntt=19990008510&Ntx=mode%20matchallany

shockonlip said:

Agreed on the main P0 statement, but don't know what you were getting at with
"(ie discharge coeffs.)". By real entrance effects I would think of BL
and maybe other things like alpha (angle of attack).

Click to expand...

Just because you make a hole bleed, slit, etc, doesn't necessarily mean any air has to flow through it. The author used the term effectiveness as a vague term in dealing with this. In these inlets one is dealing with fairly speedy supersonic flow and trying to get an appreciable amount of that flow to substantially turn and exit a hole isn't a trivial thing. Even in a stagnant pressurized container an exit hole is going to have a discharge coefficient which will limit that flowrate through it. If you look at some of what was done here is folks computed the total area (throat, bleed, slit etc) they thought they needed based upon the CR they got out of Kantrowitz formula/curve. When in actually it's the sonic mass flow you need to concentrate on and include all the fluid mechanic losses for the bled/spilled/etc flow. The LaRC swept sidewall inlets are specifically design to have a downward turning component of the compression process. At lower Mach numbers the turning is stronger, so there is more spillage which allows the inlet to start at lower Mach number and also have a variable aerodynamic contraction ratio with a fixed geometry. Inlets of this type with the inlet sidewalls swept forward have also been looked at. This turns the flow up towards the top plate or body side, which hurts the starting process. So much eventually you might end up with an inlet which won't start even if you remove the cowl or bottom plate completely.

http://ntrs.larc.nasa.gov/search.jsp?R=19900055694&hterms=trexler+inlet+inlet&qs=Ntx%3Dmode%2520matchany|mode%2520matchany%26Ntk%3DTitle|Author-Name%26Ns%3DLoaded-Date|1%26N%3D0%26Ntt%3Dinlet|trexler

Very cool poster - great background for my laptop !
Got others?

Also thanks on the "discharge coeffs" explanation.

airrocket said:

Check this out...how to do R&D on smaller budget using HP type hardware.

http://www.appliedthermalsciences.com/blog/ATSVB0026.html

Click to expand...

Yes, DSE also pointed this guy out.
He is on the east coast. I am on the other one.

Red: Grandma what big cowl lips you have !

Grandma: All the better to catch shocks off design my dear!

Or so I wonder.
Maybe I should call him.

Probably a DCR eventually.

shockonlip said:

Very cool poster - great background for my laptop !
Got others?

Also thanks on the "discharge coeffs" explanation.

Click to expand...

How's http://www.nasaimages.org/luna/servlet/view/search?q=x-43b&search=Search and http://www.space.gov.au/AustralianSpaceResearchProgram/Documents/poster-v1.pdf for a start?

I should have been clearer that I was talking about entrance effects for the bleed, etc system.

Additional reference for the Rocketdyne fixed geometry inlet showing effects of geometry on starting and performance

AIAA 99-2589, Test Results Of A Fixed Geometry RBCC Inlet, A. Goldman Boeing - Rocketdyne Propulsion & Power Canoga Park, CA, B. P. Willis NASA GRC Plum Brook Station Sandusky, OH

Cool! Thanks DSE!

shockonlip said:

Very cool poster - great background for my laptop !
Got others?

Click to expand...

A bit off the thread topic, but from a trade show.

Inward design:

airrocket said:

Inward design:

Click to expand...

Seems awfully long. What are the design characteristics, frees stream Mach #, contraction or compression ratio, etc?

some nice mag there...
http://issuu.com/magazineproduction/docs/wti_issue_2_2010_ezine?mode=embed

Some NASA/AFRL work from p.12 of the 2011 NASA FAP Hypersonics Project Overview.

I believe that TRINT is the same inlet, or very close to the same inlet shown in the Wind Tunnel mag link above on pages 15 and 106 for the FALCON program.