More Strap-On Pod Ramjet Engine Data

These images are "extras" computed from the strap-on pod ramjet performance-map data. That data covers flight Mach numbers from 1.5 to 6, and altitudes from 5000 feet to 100,000 feet. In an earlier post, the overall energy conversion efficiency was correlated vs flight Mach as almost independent of altitude. This has potential application to rough-sizing vehicles in "back-of-the-envelope" (BOE) analyses.

In this post, the pod thrust is correlated vs flight Mach and flight altitude in two graphs. The first shows net jet thrust vs Mach number parametric on altitude. Similar to the efficiency, these figures are very insensitive to altitude. The average model through the center of the data is a simple quadratic fit:

Fnj / Fnj at M4 = -.068 (M - 4)^2 + .028 (M - 4) + 1.00



The second shows the net jet thrust data at only Mach 4 as a function of altitude. The model that tracks this data very closely is a fairly simple exponential fit:

(M 4 only) Fnj / Fnj at 5 kft = 1.00 exp [-.034(h - 5 kft)^1.02]



The scaling value that converts these ratios to actual thrust is net jet thrust of a 1 square foot-size engine (based on outside diameter) at Mach 4, 5000 feet conditions. This is essentially the frontal thrust density Fnj/So = 4860.3 lb/sq.ft.

This particular engine has a translating-spike inlet for constant shock-on-lip operation at all flight Mach numbers from 1.5 to 6. Therefore, it has no additive (pre-entry) drag. The engine is sized so that it does not spill air sub-critically in this flight envelope (except a tiny amount at low speeds and very high altitudes). So, installed thrust and impulse are pretty much the same values as net jet.

The engine specific impulse data are harder to correlate, since the variation with altitude does not diminish to insignificance, the way it did with normalized thrust ratios. Still, all the curves have the same shapes vs flight Mach number or vs altitude. Two plots are given: one of specific impulse vs Mach parametric upon flight altitude, the other specific impulse vs flight altitude parametric upon flight Mach number. For BOE rough-sizing purposes, the second plot may be easier to use as a graphical estimating tool.





Once again, the impulse data are actually for net jet thrust-drag accounting. But, for this particular design, the installed numbers are the same.

Enjoy!!

Updates

On ramjet data postings:

I am working on a back-of-the-envelope set of methods to get "in the ballpark" with rocket and ramjet vehicle designs, including parallel-burn designs where both types of engine burn simultaneously. This would include both fast ascent non-lifting ballistic trajectories, and lifting-vehicle trajectories at far more modest climb angles. These are entirely different analyses from any practical standpoint. This work is still in progress, and is aimed at rough-sizing configurations that could be refined later with a real trajectory computer program model.

On the Gulf oil spill:

I stand by my two earlier posts. Although I see little or no movement toward changing the rules for deep-water drilling, I think my four suggestions, if implemented, would have prevented the current disaster. I see no need to stand down deepwater drilling for 6 months or any other extended period of time. I see a need to change the rules quickly, and that should not take more than a week or two. Don't reinvent the wheel, just use what I posted. They are:

1. eliminate the liability caps and statutes of limitations; faced with true costs, safety and preparedness will receive proper attention
2. use a double blowout preventer for the increase of reliability due to redundancy, like the Europeans do in the North Sea
3. drill the relief wells while drilling the main well, so it could be relieved (if need be) within days not weeks-to-months
4. spend some federal R&D monies on better booms, better skimmers, better absorbents, and even-better bioremediation products.

To that list I would add spend some money on developing the oil-water separation techniques so that fresh oil making a free ascent to the surface could be used.

The second post said use bioremediation in addition to the other remediation methods (booms, skimmers, absorbents). Where dispersants interfere with bioremediation or the other methods, quit using dispersants. Nothing works if you drive the oil down deep in the water as microscopic globules. Hiding the problem instead of addressing it is utterly stupid.

The federal EPA is going to have to take its blinders off regarding bioremediation. They (and many academics) seem to think that bioremediation is a new thing to be studied to death. It is not; it was used successfully in a Galveston Bay spill 20 years ago, including both on-the-water and in-the-marshlands oil. It works, we already know that, here in Texas.

How come no one else seems to be doing it? The bioremediation products are already available commercially. This is not R&D, this stuff is available for sale, now.

On global warming:

Now that El Nino is over, and the heat has returned with a vengeance, I noticed that my global warming-skeptic friends have grown strangely quiet. I don't care whether humans caused the warming or not, the real question is what do we do about it, considering the devastating effects of massive sea level rise, among other consequences.

Latest science journal estimates put the expected sea level rise at 0.3 to 1.8 meters by 2100 AD. (The trend of these estimates over the last few years has been sharply upward, by the way.) Almost a billion people live within a meter or two of current sea level. That's a big, permanent refugee migration across international borders, when this civilization demonstrably cannot handle the temporary evacuation of one city (New Orleans), within one nation's borders.

The prudent thing is to plan how to cope with this disaster, and to try to mitigate the warming somewhat, to buy some extra time for that "coping".

On the North Korean sinking of the South Korean ship:

I see no reason to change my stance, which was to blockade the North Korean navy into its ports. They were a problem on the high seas, well, don't let 'em out there any more. Simple. Direct.

As for how the North Korean government has been behaving, we should use this incident to our advantage. Rub their noses in it, with no wiggle room to save face. If we do not do that, then they will think they "won", and their behavior will never change.

On a recent birthday surprise:

My wife took me to East Texas to ride the steam train (Texas State Railroad, Rusk to Palestine and back). The real surprise was that she bought me the "locomotive cab rider" ticket. I rode in the locomotive with the driver and the fireman, and I learned how to do what they did, by watching what they did, how they did it, what they did it with, and talking with them. The locomotive was a 109-year-old A.L. Cooke 4-6-0 woodburner, that had been long ago converted to fuel oil. Depending on power levels being generated, it was 110 to 140 F in that cab. I now understand why the old time steam crews always hung out the windows: it was to stay cooler in the breeze. I had a blast!!!!!!! Thank you, my dear! Wonderful present.

On a recent trip to California:

I went to Mojave to visit a small private rocket company at the airport. This was the first time in 25 years I had been there. Mojave was about the same as I remembered. "LA sprawl" has spilled through the mountains and engulfed Palmdale and Lancaster, though. There were more buildings and businesses on the airport, and the mix of aircraft in the "boneyard" has changed.

The little rocket company was very impressive, and was interested in someday applying a technology with which I had extensive and direct experience years ago in the defense industry: ramjet propulsion. They had been looking for someone without success, when they ran across me. Apparently, I am one of very few surviving American engineers with that kind of all-around ramjet expertise and experience. It was a bit of a shock to realize that I apparently outlived nearly all of them.

Alternate fuel work:

I recently began some tests in the old ethanol VW before I re-mothball it. I reworked its carburetor with a main jet adjusting needle, and reset everything to run straight gasoline. Then, I started testing stiffer and stiffer ethanol blends in an otherwise-gasoline car. There are some driveability issues in carburetion that don't show up with fuel injection, but I was looking for the reduced intake vacuum that indicates a late timing problem. So far, I have reached an E-50 blend with this vehicle, and I have not yet seen the timing problem.

In the F-150, I saw this late timing effect at an E-47 blend. In the Nissan, I got a little past E-50 by accident, and I believe I saw the problem. (Those two are fuel injected.)

For the next VW test, I plan to evaluate timing at E-53.

All the lawnmowers, the F-150, and the Nissan are working just fine on E-25 to E-40 blends, pretty much year round. All of these are "factory stock". Their engines are cleaner than "normal" inside, and at least the truck's tailpipe is "bare steel" clean.

To have the EPA balk on raising the gasohol cap from E-10 to E-15 is utterly ridiculous stupidity on their part, or egregious corruption due to lobby monies, or both. (Probably both, in my opinion.) Brazil has used E-20 to E-25 gasohols for decades, and I am not the only investigator to suggest that E-30 to E-35 will be "just fine".

More Ramjet Performance Numbers for the Strap-On Pod

The image is a graph of overall energy conversion efficiency for the ramjet strap-on pod, for which cycle analysis performance was posted in 4 articles previously. 3 of these were dated 2-20-10, and the 4th was dated 2-28-10.

The energy conversion efficiency relates engine thrust power delivered to the airframe, to the fuel combustion energy flowing from tank storage. It is a sort of overall energy efficiency, not a cycle efficiency. The thrust power is engine thrust times flight velocity in appropriate units of measurement. The energy flowing from storage is the engine fuel mass flow, times the fuel gravimetric lower heating value, again in appropriate units. Efficiency is the ratio of thrust power to energy flow from storage.

The thrust can be reported in either of two force accounting schemes, net jet or installed. These differ primarily in whether the inlet additive (pre-entry) drag is subtracted from thrust (installed) or added to airframe drag (net jet). This particular translating-spike inlet, which maintains shock-on-lip operation at all flight Mach numbers, has no additive drag. So, in this particular case, there is no difference.

In the ratio creating the efficiency, thrust divides by fuel flow to create the ramjet engine's specific impulse. Again, normally there would be two different values, net jet and installed. But, in this particular design, there is no difference.

The ratio equation looks like this:

efficiency = (ramjet Isp)(flight velocity)/(gravimetric fuel lower heating value)

In the graph above, there is very little effect of altitude, from 5000 feet all the way to 100,000 feet. The variation with flight Mach number is almost parabolic, if one fairs through the middle of the altitudes. A parabolic model was formulated and included in the graph. That model equation is:

efficiency = -0.22(M - 4.2)^2 + 0.33

Remarkably enough, if one does not spend much time flying at speeds below about Mach 2, a simple constant average figure of 30% efficient would be a good representation for purposes of very crude back-of-the-envelope models based on energy quantities.

Calculation of these quantities is very easy to include in the cycle analysis for the ramjet engine, as the above thrust power efficiency equation indicates. Whether this has utility beyond crude back-of-the-envelope calculations remains to be seen. But, it is very intriguing.

Remediating the Gulf Oil Spill Disaster

Among all the things being used to treat the oil spill in the Gulf, I have not seen much about “bioremediation”. That is the use of oil-eating microbes to convert it to something harmless.

This is a technology that I personally know could work. A few years ago, I worked for a local Waco firm in the environmental field. One of their standard responses was bioremediation.

On the internet is a video from 20 years ago, in which the State of Texas used oil-eating microbes to clean up a tanker oil spill in Galveston Bay. This is better than absorbents, because the oil is eliminated in-place, with nothing to pick up for disposal.

I researched bioremediation to see what was available, and how best to use it. There are many firms nationwide offering commercial oil-eating microbes, and these are natural, not genetically-engineered.

I am no expert, but, from that research, I did get a sense for what works and what does not. First and foremost, these microbes work best on surfaces: oil floating on water, or oil still on the surface of soils.

That means bioremediation is ineffective if (1) the oil has soaked down into the soil, or (2) has been dispersed down into the water. That first means you cannot delay treatment for oil coming ashore on a beach or wetland, and the second means that you cannot use “dispersants”, which cause the oil to break up and migrate downward into the water.

Dispersed oil is not remediated or removed, simply relocated to where it is not visible, and to where bioremediation, booms, skimmers, and absorbents are all ineffective. In other words, dispersants act to make the damage to the environment worse, in part by hiding it!

Now, the EPA told BP to use a different dispersant, not to stop using dispersants at all. In effect, the EPA advocates using what it considers to be a “proper” dispersant, which actually makes the problem worse, but in an “acceptable” way!

My research says that the physical state of the microbes, and the additives included with them in the commercial products, do make a significant difference to effectiveness. But those issues are well-understood, so they should not hold back the application of oil-eating microbes to the open-water Gulf, or to any shoreline areas contaminated by oil.

I think I like bioremediation best, because the oil really is “destroyed” in-situ by being converted to microbe waste products, in turn non-toxic to the rest of the ecosystem. It is also self-limiting: once the oil is gone, the microbes die for lack of food.

No mess to pick up afterward, it seems to happens over days-to-months-not-years, and it’s cheap. You can spray it from an airplane or a boat. It makes good common sense.

So, I have two very serious unanswered questions:

(1)Why were we not doing this the first week of this crisis?

(2) How come the EPA did not demand this?

Plenty of Blame to Go Around for the Disaster in the Gulf

The oil rig explosion has led to the greatest environmental disaster this nation has ever suffered. Crude oil now stretches almost halfway across the Gulf of Mexico. Over one month into this, we still have two or three months to go before a relief well can be drilled. The fishing industries, and all the beach-related tourism industries, will very likely be destroyed. How long? People are still finding tar balls on Texas beaches from the Ixtoc-1 blowout off Yucatan in 1979. The current disaster is far larger: the livelihoods of millions could be destroyed for a generation or more. This is not the first American oil well drilled beyond where human divers can go. This is just the first one to “go bad”. Offshore drilling at any depth requires a permit from the Minerals Management Service (MMS). One requirement is a report explaining what the company proposes to do about any conceivable accident, and why the government should believe that they can do it. From what I have read and seen, BP’s 582-page report was not worth the paper: I think everyone now knows they are actually “making this up as they go”. Clearly, they did not take very seriously their disaster-management responsibility. MMS was specifically charged with verifying the adequacy of these disaster plans. Clearly, they failed. But, beyond that failure, why should we believe in the adequacy of any of the disaster plans submitted by any oil company? I am not happy with federal emergency responses, either. This is not the fault of the President and his administration (current or previous), but it is the fault of the massively slow career bureaucracy. Case in point: delaying construction of off-shore sand berms, because they might have some undefined future ill effect. We already know that the oil coming ashore unhindered will most definitely have a disastrous effect. Absolutely brain dead stupid! An order from the President could have broken this bureaucratic logjam, because they work for him. Neither this President, nor the previous one, issued the critical command when the time was right. So, here is my specific list of suggestions to keep this from happening again: 1. Remove both the liability limits and the statute of limitations. Faced with the true costs, they will pay more attention to safety, prevention, and preparedness. 2. Use two blowout preventers on each well, as the Europeans do in the North Sea. The compounded probability of containing the accident is much higher. 3. For wells beyond the reach of human divers, require that the main well and a relief well be drilled at the same time. If the worst happens, the relief well could be completed in days, not months. 4. Spend federal money now developing sand berms, better absorbents, and better boom technology, so that emergency response in the future is much more effective and a lot faster. 5. Issue executive orders immediately to get these bureaucratic agencies moving very much more quickly, perhaps even anticipating these disasters. No more Katrinas.

It really was the North Koreans who sank the South Korean ship

The latest reports indicate that a torpedo fired from a North Korean submarine sank a South Korean ship with a loss 46 sailors. Whatever else one might say, that was an unprovoked attack, which has (so far) led to no reprisal against the perpetrators. This was the largest cost in lives for a single incident, since the original 1950-1953 Korean War. That war was never resolved by a treaty, only halted by an armistice. While diplomats always dither, I suggest that this incident demands real action, because of its egregious nature, and the magnitude of the death toll. The problem is provocative action by units of the North Korean navy, committed upon the high seas. So, the solution is that no units of the North Korean navy should be allowed upon the high seas, until their government changes its idiotic ways. I rather doubt that the UN security council would ever do anything substantive. They have almost never acted responsibly, not since that original Korean war. So, it is the South Koreans and their allies that must act, on their own. My suggestion: allow no North Korean naval vessel passage on the high seas, until the North Korean government acknowledges the sinking it perpetrated, and promises massive policy change. Period. No room to maneuver, no room to "save face". The penalty is sink-on-sight. Then, the South Koreans and their allies must actually carry out this threat. The North Koreans will inevitably challenge such a declaration, and they must suffer for it. Sinking surface ships is fairly easy; sinking submarines is more challenging. So, I think a US navy battle group or two must be committed to this, and they must be free to sink whatever they see. No questions asked. Once they get their noses rubbed in it, I think the North Koreans may steer a different, less objectionable, diplomatic course. This will be true in spite of the megalomaniac idiot they have for a dictator, because he depends upon the North Korean military to stay in power. While extremist, those generals are not fools. We will have to hurt them to achieve this result, though. We must be prepared to do exactly what I propose: sink the bastards. No half measures. No mercy.

On Really Bad Drivers

I see some really idiotic behavior on the roads around here all the time. I never see anyone pulled over and ticketed for it, either. Some of the worst offenders seem to be rather rich and priviledged, too. Others are obviously "new grads" from the local driving school, which makes me wonder what that school actually teaches.

These behaviors include ignoring yield signs (including the implied yield on a freeway entrance ramp), cutting people off, following too close, high-speed weaving, pulling out without looking first, passing in no-passing zones, failing to dim headlights, and running red lights and stop signs. These are all basically "being in the wrong place at the wrong time doing the wrong thing" offenses.

In addition, I see slow traffic not keeping right, vehicles wandering all over the road out of their lanes, and drivers way too distracted by cell phones to even be on the road at all. That last one is already illegal under the old "failure to keep a proper lookout" law; so we don't need a new law about cell phones. We just need to enforce the one we already have.

Trouble is, the only real enforcement I see going on is speed and parking tickets (and precious few of those). I don't know if that is because it's just so easy to sit and wait for the radar alarm go off, or if it's because the lawyers and judges have so screwed up the court process that only speed and parking tickets "stick" anymore. (If it is the lawyers, then maybe Shakespeare was right.)

In Texas, under most conditions on the highway, it is "being in the wrong place at the wrong time doing the wrong thing" that causes the accidents, not speeding itself. Speed merely sets the level of damage as the accident occurs. It's only in residential areas, city streets, parking lots, and rainy, foggy, or icy weather that speed itself is a prime cause of the accidents.

So, if we were serious about reducing highway traffic accidents, we would be demanding that our police ticket the egregious behaviors (that I listed above) as higher priorities over speeding. I simply don't see that going on. As for residential areas and parking lots, that is where speed causes a lot of the accidents, and that is where speeding tickets need the higher priority.

What kind of body count does it take to get these priorities straight? Isn't 40,000 a year enough?