Alphasim B-58 first flight comments...not exhaustive!

[Guest Coneman]

Well, if you can't dazzle them with brilliance....

[Guest Tophatter]

> It would be>impressive to say we obtained the actual Mach drag chart from>Lockheed, buried in a dusty vault somewhere, and used that,>but we thought that to be a long shot).>Yes, it'd be very impressive, given that Lockheed didn't build the B->58!No but Convair (General Dynamics) did and they were bought by Lockheed Martin so they would be the ones with the info.Bud

[Guest Alpha_J]

>>...the gage used in the>>panel, unfortunately, reads out uncorrected N1 RPM rather>than>>corrected N2, which is what the actual gage in the real>>airplane provides....>>anyone who can edit a text file can easily update this by>>adding the word "corrected" in front of "N1" in the .xml>file>>for each of the four gages, takes only a few minutes.>>Noted...but I'm stunned that you could have put in the kind of>testing you allude to and not notice that the indicated power>settings are more than 10% low in the high-altitude high-speed>regimes where this jet flies. As you point out w/r/t the>gauges...easy to fix in xml, so why is there no fix already>posted on your site?I have a custom panel I use for flight model development and did not see the final panel until after the plane was released. Due to considerations of time, development of the panel, visual model, textures, and flight dynamics happen in parallel and often I do not see the final assembly until after release. This gage issue was a simple oversight, easily corrected.>>>Your comment about the mach drag in the .air file was>>interesting as well. It is not always necessary to have a>>value in this lookup table. >>>Many of these tables can in fact be omitted>>from the flight model in many cases. I assume you concluded>>there was too little drag because of the low RPM figure, but>>that RPM figure was wrong because of the gage. >>I started looking at the drag figures because of both the low>power settings on the gauges, and the low fuel flows...range>(unrefueled) of the B-58 was around 3,400nm, but with the low>fuel flows I saw I had more than double that.>>>(It would be>>impressive to say we obtained the actual Mach drag chart>from>>Lockheed, buried in a dusty vault somewhere, and used that,>>but we thought that to be a long shot).>>Yes, it'd be very impressive, given that Lockheed didn't build>the B-58!Convair was sold to General Dynamics, which was then acquired by McDonnell-Douglas and finally Lockheed. If anyone would have those old archives it would have been Lockheed.>>>To expand on that a bit, what we want out of flight dynamics>>is a net effect. Yes, it is true that the real aircraft had>>both additional drag (Mach drag) as well as additional>cruise>>lift at Mach 1.4. However, the net effect of this>additional>>lift and drag is what we are interested in. If they, in>>effect, cancel one another out then there is little reason>to>>plug numbers into those tables. Many aerodynamic parameters>>are combined into a "net effect" in Microsoft's FS series,>>especially so in FS9. It's part of the design strategy of>the>>sim.>>I'm a tiny bit familiar with MSFS FDE design. That said...>>Lift and drag do not cancel each other. They are forces>acting perpendicular to one another...how can one cancel the>other? That idea just does not make sense.I am referring to the relationship of two specific tables, one for Mach drag and the other for cruise lift. This reference is very specific to that file and those lookup tables. The effect of increasing cruise lift is to increase the L/D ratio, and vice versa.>There is no offset elsewhere in the MSFS flight dynamics to>the effects of shock (mach) drag. The real airplane>experiences a significant spike in drag as it accelerates>through the transonic zone, something reasonably approximated>by a realistic entry in the mach drag table. It takes a lot>of energy to bust through the brick wall at Mach 1...your FDE>does not exhibit this behavior, which is a defining trademark>of the supersonic aircraft in its generation.>Performance in the subsonic regime is acceptably by-the-book,>and I'll grant you that part was non-trivial to do. The>supersonic dynamics really aren't there yet. Some of>it...like the shock drag issue, are sooooo easy to fix. >Synching up throttle, nozzle, and visual effects is another,>but a bit more difficult.>>There's some good work here, but as I noted earlier about the>panel, it's incomplete. At the $25 mark, people are going to>expect a little more I think.>>Hope to see you work through these issues and not just dig in>and defend the errors.>>Cheers>>Bob Scott>ATP IMEL Gulfstream II-III-IV-V L-300>Santiago de Chile>

[Guest Alpha_J]

>Lift and drag do not cancel each other. They are forces>acting perpendicular to one another...how can one cancel the>other? That idea just does not make sense.I didn't answer this properly, but lift and drag do indeed have opposing effects. That is why the lift/drag ratio, or L/D, is such an important part of aircraft performance assessment.Again, I don't mean to lecture to anyone who already is aware of this and I am not trying to sound like a know-it-all (I most certainly am not); I am just responding to your comment.Lift is created in one of two ways; either by increasing the airflow over the wing, or increasing the angle of attack of the wing. There is of course some minimum airflow required to get airborne, so we are assuming the plane to be flying above stalling speed. No matter which one we use, drag increases. If you have a plane flying along in a steady state of cruise at a fixed speed and altitude, and you increase power without doing anything else, the plane will begin to climb. You must then trim the aircraft to reduce the angle of attack to reduce the amount of lift the wing is creating back to where the forces are in equilibrium. The plane will then fly level again.The plane is now flying faster at the same altitude but we have increased the drag of the aircraft, because an increase in lift always results in an increase in the induced drag, which is drag created by additional lift. The lift/drag ratio is so important because it tells us how efficient the wing is. The more induced drag the wing creates for a given amount of lift, the lower the plane's top speed, climb rate, and ceiling will be. And the fuel consumption will be higher at cruise for any given speed.If you increase the lift of an airfoil while leaving the drag value the same, you have more efficiency, meaning more speed, range, and a higher ceiling. By the same token, if you can reduce the drag of an airfoil while retaining lift, you get the same result. A good example of this is the laminar flow airfoil on the P-51 Mustang, which had excellent lift/drag characteristics. The aspect ratio of a wing also has a great effect on this, but now we are comparing wings with airfoils. Both have an effect on the final product, the aircraft.The bottom line is this: lift and drag do cancel one another which is why the L/D ratio is still the gold standard in measuring aircraft performance in most cases. If you can increase lift and keep drag constant, you have increased the plane's performance. By adding drag in Table 430, or increasing lift in Table 401, you are affecting the plane's outright performance by directly affecting the L/D ratio. These two tables have opposing effects. Crank up the values in Table 401 and you will note that the plane now flies faster at the same altitude and throttle setting. Crank up the values in Table 430 and the plane will fly slower. These two tables represent the two opposing forces in the L/D equation and are therefore very useful for fine-tuning aircraft performance.You also commented that since lift and drag are forces that work perpendicular to one another, it didn't seem to make sense that they were related, or could "cancel" one another. Often, forces working perpendicular to one another are directly related. A very good example of another such relationship is that of a common gyroscope. If you were to apply a force to a spinning gyroscope, that gyroscope would respond by moving in a plane 90 degrees opposed (perpendicular) to the place you applied the disturbing force. There are all kinds of physical relationships that don't seem to make immediate sense, but they are nevertheless there.As far as what the flight dynamics engine is doing in the background, no one knows this for certain because there are data that cannot be directly extracted from the simulator. This is well-known to those programmers who've reverse-engineered a lot of this stuff. We know how to change a lot of things to affect the flight dynamics, but we can't change everything that's going on in there. There are many default behaviors hard-coded into the sim and not all are completely understood, nor can all of them be modified. Here's an excellent article about the strategy used in creating the flight dynamics engine for anyone who's not seen it:http://www.microsoft.com/games/flightsimul...4_zyskowski.asp

[Bob Scott 7,705]

>I didn't answer this properly, but lift and drag do indeed>have opposing effects. That is why the lift/drag ratio, or>L/D, is such an important part of aircraft performance>assessment.No, I would agree that lift and drag are related, and complement each other, but they certainly do not have opposing effects.>Lift is created in one of two ways; either by increasing the>airflow over the wing, or increasing the angle of attack of>the wing.I think you mean lift is increased in one of those two ways. But in the supersonic regimes, lift may also very well be increased by *decreasing* the airflow over the wings (in the case where a shock stall is in progress due to shock wave effects on the wing's airflow), or it might be increased by *decreasing* the angle of attack if the current AoA is above the critical AoA (IOW, the wing is stalled).>There is of course some minimum airflow required to>get airborne, so we are assuming the plane to be flying above>stalling speed. No matter which one we use, drag increases. >If you have a plane flying along in a steady state of cruise>at a fixed speed and altitude, and you increase power without>doing anything else, the plane will begin to climb. Only if positive static stability is assumed. And only if the thrust vector of the engines does not appreciably deviate from alignment from the longitudinal axis of the jet. Add power on an F-22 with the thrust vectoring nozzles stuck down and you will see a pitch down rather than up.>If you increase the lift of an airfoil while leaving the drag>value the same, you have more efficiency, meaning more speed,>range, and a higher ceiling. By the same token, if you can>reduce the drag of an airfoil while retaining lift, you get>the same result. A good example of this is the laminar flow>airfoil on the P-51 Mustang, which had excellent lift/drag>characteristics. The aspect ratio of a wing also has a great>effect on this, but now we are comparing wings with airfoils. >Both have an effect on the final product, the aircraft.>>The bottom line is this: lift and drag do cancel one another>which is why the L/D ratio is still the gold standard in>measuring aircraft performance in most cases. If you can>increase lift and keep drag constant, you have increased the>plane's performance. By adding drag in Table 430, or>increasing lift in Table 401, you are affecting the plane's>outright performance by directly affecting the L/D ratio. >These two tables have opposing effects. Crank up the values>in Table 401 and you will note that the plane now flies faster>at the same altitude and throttle setting. Crank up the>values in Table 430 and the plane will fly slower. These two>tables represent the two opposing forces in the L/D equation>and are therefore very useful for fine-tuning aircraft>performance.The bottom line is that, *no*, lift and drag do not cancel each other. Regrettably, your argument is incomplete and misses a great deal. One giant, glaring omission here, for example, is with respect to forms of drag other than induced drag. L/D ratio is a function of the wing planform, but parasitic drag and wave drag are not functions of lift.The reality is that for delta-wing area-rule designs like the Hustler, L/Dmax still drops off as the aircraft enters the transonic regime albeit at a somewhat lower rate than for other wing designs.>You also commented that since lift and drag are forces that>work perpendicular to one another, it didn't seem to make>sense that they were related, or could "cancel" one another. >Often, forces working perpendicular to one another are>directly related. A very good example of another such>relationship is that of a common gyroscope. If you were to>apply a force to a spinning gyroscope, that gyroscope would>respond by moving in a plane 90 degrees opposed>(perpendicular) to the place you applied the disturbing force.> There are all kinds of physical relationships that don't seem>to make immediate sense, but they are nevertheless there.Of course they make sense. Vector math easily explains both of these. In the case of a gyro, you have energy already at work in the system in the form of the angular momentum of the spinning wheel, and the conservation of that angular momentum is what translates force applied in one axis to a force in another. When a force is created on the wing on an aircraft moving through the air, its vector is not vertical...we refer to the vertical axis component as lift, and the longitudinal force component as induced drag. They do not cancel at all...they in fact are additive, and their vector sum is the actual force produced on the aircraft by air flowing over the wings. *By definition* lift and induced drag are perpendicular components of the same vector force.>As far as what the flight dynamics engine is doing in the>background, no one knows this for certain because there are>data that cannot be directly extracted from the simulator. For certain, the internals of MSFS are fuzzy. But when I look at the forest rather than the trees, it's obvious to me that the Alpha B-58 FDE is missing something big in between approach speed and high-speed Mach 1.4 cruise, where the model approximates the numbers in the flight manual. The dynamics of getting through the sound barrier is a big part of what makes this plane and those of its era interesting to me.CheersBob ScottATP IMEL Gulfstream II-III-IV-V L-300Santiago de Chile

[Guest Alpha_J]

>>>First off are the flight dynamics - these flight dynamics>>believe it or not, are based on the pilots manual - we went>>through extensive testing to ensure that the dynamics>>exhibited by the real life Hustler as as close as possible>>incorporated into our version. A question was posted on our>>ALphasim forum about engine spool up being exceptionally>slow>>- well this plane is from the late fifties well before quick>>spooling engines had been developed. >>No, and double-no! The J-79 engine was also used in>the F-104 Starfighter and later in the F-4 Phantom. The>engines in this era were low-bypass or no-bypass turbojets>that jumped at your command. What you'r suggesting about the>engines of this era, and this engine in particular is>completely wrong.He is referring to spool-up from idle; you are of course correct if referring to engine response once you're up and flying and in the powerband. The spool-up on the Hustler is really not too slow, it takes about 20 seconds to get from idle (67% N2) to full military thrust (100% N2). If memory serves, the J47 used in the B-47 could take as long as 40 seconds or thereabouts.I just did a quick check and unless my source is wrong, current regulations require a jet engine to spool up from idle to go-around thrust in 8 seconds. I am told this figure is still about the norm for most passenger jets.

[Guest Alpha_J]

>Regrettably, your argument is incomplete and misses a great deal. It is not an argument, it is a statement of aeronautical fact that can be verified in any "Aerodynamics 101" -style textbook. What I was attempting to do here was to provide a simple explanation to the average flight simmer of the relationship between lift and drag. They are directly related and that's what I wanted to get across. There are other forums better-suited to complicated discussions of supersonic and transonic aircraft behavior. Those discussions can go on forever and are very enjoyable, but they don't really relate to why I jumped in here.

[Guest JIMJAM]

I do not know about how most the other Alpha buyers feel but its great to think the FM is as close to the real thing as it can get.But Im happy if it feels right,fun to fly and the numbers are close to the actual.When I buy an Alpha plane I always knew what I was going to get for $15-$20. A nice looking plane,decent 2d,crap VR and a good flight model.And I was happy.But for $25 and up I dont care if the FM was tested by actual pilots or a dusty Lockheed manual was used for authenticity.Just give us gauge backlighting, a vr pit that actually works and can be used at night.And just basically spend a little more time and effort on the appearance of the cockpits. Most of us are not running 486 computers anymore so the whole "we do it for the frame rates" does not hold water.Really looking forward to the Raptor but if the vr is useless and has no gauge lighting but just the same old flood lighting, it had better be less than $20 or Im out.

[Bob Scott 7,705]

Well, then I'll chalk it up to a case of what you're saying may not be what I'm hearing. Clearly you have some idea of what you're doing...the FDE in the Alpha B-58 aren't a complete basket case...but the panel is. Your explanation regarding the poor choice of gauge parameters by your panel designer shed light on the worst of the odd performance issues. With a new batch of xml gauges I just wrote, things are looking much better. Of course the fact that I have to write a new set of gauges for a payware product to make it work right is another issue...RegardsBob ScottATP IMEL Gulfstream II-III-IV-V L-300Santiago de Chile

[Guest Alpha_J]

>Well, then I'll chalk it up to a case of what you're saying>may not be what I'm hearing. Clearly you have some idea of>what you're doing...the FDE in the Alpha B-58 aren't a>complete basket case...but the panel is. Your explanation>regarding the poor choice of gauge parameters by your panel>designer shed light on the worst of the odd performance>issues. With a new batch of xml gauges I just wrote, things>are looking much better. Of course the fact that I have to>write a new set of gauges for a payware product to make it>work right is another issue...>>Regards>>Bob Scott>ATP IMEL Gulfstream II-III-IV-V L-300>Santiago de Chile>Just hold onto your ejection seat, we're fixing ALL of this, including the transonic/supersonic flight dynamics. The revisions to the flight model are done and the panel and documentation are well underway. No need to do a thing unless you want to, all these issues will be resolved.Some highlights...-Reworked gages with tooltips on mouseover.-Transonic "barrier" with noticeable trim change and deceleration-Accurate fuel consumption at subsonic, mid-supersonic, and high-supersonic speeds (0.9, 1.4, and 1.8 Mach)-reworked throttle quadrant indexing; power schedule now corresponds exactly to the throttle quadrant markings for easy and realistic power setting changes-afterburner effects now coincide exactly with the afterburning range on the throttle quadrant-new documentation added to explain the location and function of all VC switches (there are many)

[Guest seniorcrown]

Just for closure to this topic, we have a free to download 'optional' enhancement of the B-58 Hustler adding fuel transfer switches, main pod that depletes the fuel in the pod when dropped, much more information including a landing tutorial in the checklists and various other enhancements.To get your download, you need to go back to the Alphasim Store, click on My Downloads, in there should be the Hustler, you'll need your original password (the same as when you're buying the aircraft for the first time).I hope you like it!David.AKA Alphasim-Quid21