hyperion

Hi Jan,same to me like Tom, I didn't miss it but I didn't understand until now. I am an XML newbie and it was a bit late late at night. I learned a lot from all your replies and that was it worth anyway, so thank you again.Erich

Hi Tom,thanks, it helped a lot, with the alt coded symbol I got the degree sign, my complete tooltip is now <Tooltip id="Tooltip"> <DefaultScript>Engine 1 Cyl. Head Temp. (%((L:SE chtAV celsius Eng1, celsius))%!d! °C)</DefaultScript></Tooltip> But with a blank between the # and 176 the gauge was not loaded, I had to put them together.Erich

Thank you for your suggestions, but it doesn't work, see the attached picture. The escape code is represented literally. Obviously can't it be used in this position.Erich

This one now works: <Tooltip id="Tooltip"> <DefaultScript>Engine 1 Cyl. Head Temp. (%((L:SE chtAV celsius Eng1, celsius))%!d! C)</DefaultScript></Tooltip> The reason why the previous version doesn't work is the degree sign '°' before the "C". I found out by trial and error. The degree sign breaks the code. I wonder if there is an escape sequence which allows to put in a degree sign. I have searched the SDK but found nothing about. Very strange this tooltip mumbo jumbo.Erich

Hi Jan,what I tried now is this <Tooltip id="Tooltip"> <DefaultScript>Engine 1 Cylinder Head Temperature</DefaultScript> </Tooltip> This works, the gauge is loaded and I can see the tooltip text.But when I do <Tooltip id="Tooltip"> <DefaultScript>Engine 1 Cylinder Head Temperature (%((L:SE chtAV celsius Eng1, celsius))%!d! °C)</DefaultScript></Tooltip> the gauge will not be loaded. I have no idea what is wrong. Unfortunately I do not know what the difference between FS9 or FSX syntax is. I don't understand the FSX SDK , no examples or help. So I look in gauges from other people how they did it.Erich

Thank you. I tried your suggestion but had no luck, same as before the gauge will not be loaded. Has someone else an idea?Erich

Thank you,Erich

Hi Nick,where can I find the tutorial? You mentioned your site but I do not find a link.Erich

Hi,I want to modify the tooltips for the cylinder head temperature gauge of the default grumman goose in FSX with my own tooltips. The default tooltips are <Tooltip id="Tooltip"> <DefaultId>TOOLTIPTEXT_ENG1_CHT_CELSIUS</DefaultId> <EnglishId>TOOLTIPTEXT_ENG1_CHT_FARENHEIT</EnglishId> </Tooltip> When I change this with my code, the gauge will not be loaded, at least it is not visible on the panel. I did this change according to a post I found in the forum. <Tooltip id="Tooltip"> <code>"Engine 1 Cylinder Head Temperature (%((L:SE chtAV celsius Eng1, celsius))%!d! °C)"</code> </Tooltip> Please, can anyone help me and tell me what is wrong with my code?Kind regardsErich

Hello Tom, hello Gunter,sorry for my late reply but I was very busy the last days. Thank you for your comments, notes and interest. As I short mentioned in my first post I work on a method to calculate the cylinder head temperature for air cooled engines. This method requires to know ihp but before I go in further details I will again come back to my question how FS calculates ihp.In the meanwhile I had a mail exchange with Hervé Sors who developed the AFSD tool. I asked him how AFSD calculates ihp. The anwser was quit simple. AFSD reads table 509 (friction torque vs rpm) and calculates from this friction power, thusihp = bhp (calculated by FS) + friction power from table 509I thougt the other way round, that FS calculates first ihp from values found in the *.cfg file and in flight values and then subtract friction power to get bhp. This procedure seemed more logical to me. I looked inside the code from flightgear which uses JSBSim as engine. Flightgear calculates first ISFC (indicated specific fuel consumption) and from this ihp and at last bhp.As the gauge I develop is written in xml I have no chance to read table 509. Therefore I must find a method to calculate ihp myselfs.Now an answer to Gunter's post about the Realair SF-260. What you calculated is the so called brake thermal efficiency and indeed 30% is a good value. According to (Heywood, Internal combustion engine fundamentals) the power generated by the fuel isP_fuel = FFR x Q_hvFFR = fuel flow rateQ_hv = lower heating value of the fuelAnd further isP_fuel = Pi + P_heat = Pb + Ptf + P_heat withPtf = Pfp + Pf_othersPi = indicated powerPb = brake powerPtf = total friction powerPfp = piston friction powerPf_other = other friction power, e.g. bearings, valve driveP_heat = power loss through exhaust gases, cylinder wall heat transfer, oil, unburned fuel etc.An other picture which I have from a book (D. R. Pye, The internal combustion engine, Vol. II, The aero engine, 1934) gives the following power balance sheet for an aircraft of those days:Fuel = 100%- 70% heat losses = 20% cylinder wall + 50% exhaust gases= Indicated power = 30%- 5% mechnical losses = 3% pistion friction + 2% auxiliaries and other friction= Brake power = 25%- 6% Propulsion losses (Airscrew) = 3% induced (slip stream) + 3% profile (air friction)= Thrust power = 19%- 0 to 12% power to raise weight + 7 to 19% loss in aeroplane resistanceBut now to my gauge project. When I had the idea I have been wondering if not NACA has done some investigations on the subject of air cooled engine cooling. Most of these old reports are public available from the nasa reports serverhttp://ntrs.nasa.gov/search.jsp?Ne=2&N=17 or http://naca.central.cranfield.ac.uk/I found a lot of reports about cooling and in particular NACA TN 612 which describes a method to calculate the average cht of an air cooled engine. A lot of these reports I found investigate also the influence of the engine cowling and cowl flaps or cooling slot on the engine cooling. The so called NACA cowling was one of the results from those invesitgations. Nearly all later radial engine cowlings are a form of NACA cowling.A very important parameter for the cooling of an air coolded engine is the cooling air pressure drop across the cylinders. The higher these pressure drop the better the cooling. To increase the pressure drop accross the cylinders so called baffle plates were installed between the cylinders. These baffle plates forced the cooling airstream to flow only through the cooling fins and because of this the air speed up between the fins and therefore the heat transfer was drastically increased.Now the method from the NACA TN 612 needs ihp or charge air flow and cooling air pressure drop. My first problem was how to get cooling air pressure drop. Ather scanning and reading a lot of NACA studies I found a report called NACA TN 680 from which I derived a method to calculate the cooling air pressure drop. The other Problem is that either charge air flow or indicated horse power is needed. For the moment I help me with a workaroud and calculate ihp from bhp with a simple relationihp = 1.16 x bhpI developed two gauges in xml, which was very hard, because these were my first gauges an they have a lot of math (3 dimensional functions) in it. One gauge calculates the cooling air pressure drop and one gauge, which is engine specific, calculates cht. The engine specific gauge is for a Pratt & Whitney Wasp Jr. R--985. I have in the meanwhile data for other engines as well and the gauge can easily be adapted. Up to now I have working samples which needs some optimization and a documentation. I developed it under FSX but I think it can very easy be adapted to FS9 maybe without changes. I had no time until now to check it.The Problem with my method is that the cooling pressure drop gauge must be adapted to the aircraft. There are 4 factors which needs adjustment. For this I have an excel calculation sheet in mind but until now not yet imlemented.In the attachement you find the structograms from the gauges so you can have a view on their structure. Because I have not much spare time at the moment I think I need at least 6 weeks to make it ready for the public.The attached files are SE_capd_Eng1_v102 (calculates cooling air pressure drop) and SE_PW_R-985_cht_Eng1 (calculates cht for an R-985 Engine).On the other side when I see Tom's method I doubt that my method is really handy.Erich

Hello,I am new to xml gauge design and develop currently a gauge in which I need the indicated horse power to calculate the cylinder head temperature of air cooled engines. In the SDK I found only a sim variable which gives brake horse power. I tried to calculate ihp with equations from an engineering book about internal combustion engines. These equations are simplified descriptions of the real engine behaviour or otto cycle. Some values in these equations depend themselves on air fuel mixture conditions which cannot be calculated easy.Until now I had no success with my calculations. All my figures I calculated are way off from the values I observed in flight tests with the AFSD tool. Please, can anyone in this forum point me in the right direction or can tell me how flight simulator calculates ihp? Thank you in advance.Kind regardsErich