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Aviation Forum / General / Soaring / September 2008need for dial altimeter?
I am in the process of designing the instrument panel/layout for my HP-24. Still a ways to go before I will need it, but it is raining out and my CAD program is running and so is my imagination..........so.............I was reading about the new Tasman Data Module on Paul R's website and see that it provides pressure altitude. I will be using a GPS to run my PDA, that gives GPS altitude, if I use the Tasman vario and data-module package, would I really need a dial altimeter? Thanks, Brad Hi Brad, I believe you will still need a certified altimeter in your glider. Paul Remde Cumulus Soaring, Inc. http://www.cumulus-soaring.com >I am in the process of designing the instrument panel/layout for my > HP-24. Still a ways to go before I will need it, but it is raining out [quoted text clipped - 9 lines] > Thanks, > Brad > Hi Brad, > > I believe you will still need a certified altimeter in your glider. If it is being built in the U.S. under FAA amateur built regulations, then I believe none of the instruments need to be certified. > Paul Remde > Cumulus Soaring, Inc. [quoted text clipped - 13 lines] >> Thanks, >> Brad yes, this will be an Experimental/Amateur built CofA. I think I remember Danny Howell saying that the instrumentation in the Lighthawk was going to be just a Flytec hang gliding MFD. It would be nice not to use up panel space for a dial altimeter, but on the other hand, my eyes aren't as good as they used to be either, and the 3.125" altimeter is very easy to read. ahhhh................descisions! Brad > > Hi Brad, > [quoted text clipped - 22 lines] > > - Show quoted text - > yes, this will be an Experimental/Amateur built CofA. > [quoted text clipped - 8 lines] > >Brad Wouldn't a glass-cockpit soaring instrument, say something like the new ClearNav from NK, provide even better situational awareness if it had an airspeed strip down the right edge and an altitude strip down the left edge? How about adding "altitude required for next waypoint" and "speed to fly" indicators to those strips? I'd sure like to have them....but, then, I'd like to have a horizon, too. And a G-meter strip next to the airspeed strip. Oh, and how about a vario strip next to the altitude strip? With real-time and average indicators? Maybe a voltmeter? A compass? Synthetic 3D terrain view? Thermal markers? What else do y'all think might be useful? Sounds like a whole new class of instrument, an "ESIS" or "Electronic Soaring Information System". Put all that on a 12inch-diagonal daylight visible screen and the only "steam guages" I'd have in the cockpit would be a compass and 57mm airspeed indicator. Just in case. Hmm, sounds like an idea for a future "Soaring Tech" article..... See you on the porch, - Bill > Wouldn't a glass-cockpit soaring instrument, say something like the new > ClearNav from NK, provide even better situational awareness if it had an [quoted text clipped - 18 lines] > > - Bill All well an' good, but to gain wide acceptance it needs to be energy efficient with battery back-up for at least 5 hours on two AA cells. bumper zz Minden If you are redesigning the panel on a the HP-24 that is already certificated you "may need to" look at the original certification papers and see what is required or stated for certification. You will need to meet the original certification requirements. If the Tasman data module reports pressure altitude and can be adjusted based on local altimeter settings like a standard altimeter.. a dial altimeter may not be required. But.. will it still work if you loose electrical power? Best to put in a small diameter mechanical altimeter as a back up. You'll have a mechanical vario as a back up in case of electrical problems won't you? Why not an altimeter. BT >I am in the process of designing the instrument panel/layout for my > HP-24. Still a ways to go before I will need it, but it is raining out [quoted text clipped - 9 lines] > Thanks, > Brad > If you are redesigning the panel on a the HP-24 > that is already certificated... You will need to meet > the original certification requirements... Badgers? We don't got to show you no stinking badgers. Thanks, Bob K. On the last home-built I regestered, the federallies required a mechanical airspeed, altimeter and compass........nothing else. But I have observed that the panel I am now flying has altitude displayed all over the place, in two GPS's, in the SN-10 and in the transponder. The large altimeter takes up a lot of space and provides the least important info..........................we can all estimate our altitude for landing, can't we? The rest of the time its just nice to know info. JJ > > If you are redesigning the panel on a the HP-24 > > that is already certificated... You will need to meet [quoted text clipped - 3 lines] > > Thanks, Bob K. > On the last home-built I regestered, the federallies required a > mechanical airspeed, altimeter and compass........nothing else. But I [quoted text clipped - 4 lines] > altitude for landing, can't we? The rest of the time its just nice to > know info. Except when you're flying in the among controlled airspace, where neither GPS altitude (geometric) nor transponder altitude (QNE) do you any good. Loggers usually can give you QNH altitude, provided you set them correctly and your battery isn't flat. Transponders give Flight Level (assuming they are working properly), so will give the altitude ATC are intereted in. That's how they know what FL you are at when not talking to them. >> On the last home-built I regestered, the federallies required a >> mechanical airspeed, altimeter and compass........nothing else. But I [quoted text clipped - 9 lines] >any good. Loggers usually can give you QNH altitude, provided you set >them correctly and your battery isn't flat. >>> The large altimeter takes up a lot of space and provides the least >>> important info..........................we can all estimate our [quoted text clipped - 8 lines] > so will give the altitude ATC are intereted in. That's how they > know what FL you are at when not talking to them. The pilot still needs to know msl altitude, because that's how the airspace is designated at 18,000' and below in the USA. Also, elevations (airports, mountains, obstructions, etc) use msl, and other gliders and aircraft will report their altitudes in msl.  SignatureEric Greenwell - Washington State, USA * Change "netto" to "net" to email me directly * Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4 * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more * "A Guide to Self-launching Sailplane Operation" at www.motorglider.org > Transponders give Flight Level (assuming they are working properly), so > will give the altitude ATC are intereted in. That's how they know what > FL you are at when not talking to them. The controller see your transponder altitude CORRECTED for the local pressure. So don't give them the number off the transponder display unless the current pressure is 29.92 That's why the altimeter must be calibrated when you calibrate the transponder. You must be able to set the altimeter to the current (not what it was several hours or hundreds of miles away) before talking to ATC, and that is why they will give you an altimeter setting on initial contact unless you indicate you have current ATIS info. -Tom > > Transponders give Flight Level (assuming they are working properly), so > > will give the altitude ATC are intereted in. That's how they know what [quoted text clipped - 12 lines] > > -Tom Actually this is a common misconception, (one of several reported recently in the Safety Corner in Soaring magazine). The encoder/ transponder/altimeter system is checked as a part of an install and you must also do this if the static system is touched during maintenance. Subsequent checks for aircraft operating VFR are only required to test the transponder RF/signal properties and do not need to check the altitude calibration. IFR calibration do. See FAR 91.413 appendix F (RF/signal properties only) and Appendix E (install/static maintenance and IFR checks). Back to the original question, I would not want to fly any aircraft without the ability to reliably (i.e. when the battery dies) know and be able to report pressure altitude. Darryl > Back to the original question, I would not want to fly any aircraft > without the ability to reliably (i.e. when the battery dies) know and > be able to report pressure altitude. > > Darryl If your battery dies, wouldn't you lose your ability to report anything to anybody? I'm not suggesting we fly around without an altitude readout of some kind, but does it have to be the big, old 80mm round dial? Why can't I use the pressure altitude displayed in double height on the home page of my SN-10. Keep the black cursor on it, so my altitude can be read at a glance. If I should have the SN-10 on another page, I can always read pressure altitude to the nearest 100 feet off my transponder. If for some reason I'm unable to use any of the above, I can always read pressure altitude off the GPS (model 20). Most of us have two batteries so we can switch if the primary goes dead. JJ > I'm not suggesting we fly around without an altitude readout of some > kind, but does it have to be the big, old 80mm round dial? Why can't I No it hasn't to be 80mm, mine is 57mm. Aside from this, yes it has to: More than once I was happy to be able to continue my flight under a class C ceiling despite of two flat batteries. Besides, many contries reqire gliders to be equipped with a certificated altimeter. > > Back to the original question, I would not want to fly any aircraft > > without the ability to reliably (i.e. when the battery dies) know and [quoted text clipped - 16 lines] > dead. > JJ Yes, assuming the backup handheld dies as well, then I'd just be talking to myself. I fly a certified glider so I have no choice but to follow the equipment list. You tell us J.J. what is the requirements for homebuilt/experimental and racing/exhibition/experimental. Darryl > I fly a certified glider so I have no choice but to follow the > equipment list. You tell us J.J. what is the requirements for > homebuilt/experimental and racing/exhibition/experimental. > > Darryl Alas, yes they both require old fashioned dial altimiters. With todays glass cockpits, I'm wondering if this requirement isn't outdated? JJ > Alas, yes they both require old fashioned dial altimiters. With todays > glass cockpits, I'm wondering if this requirement isn't outdated? > JJ JJ - Can you, or anyone else, reference a regulation on altimeters that includes the word DIAL. 91.205.b.2) requires for VFR flight an "altimeter" 91.205.d.5) requires for IFR flight "a sensitive altimeter adjustable for barometric pressure". Neither requires a dial and neither requires a mechanical instrument. Andy > > Alas, yes they both require old fashioned dial altimiters. With todays > > glass cockpits, I'm wondering if this requirement isn't outdated? [quoted text clipped - 11 lines] > > Andy I am also building a homebuilt sailplane and talked with the DAR (designated airworthiness representative) about the instrumentation. The answer I got was that it's pretty much up to him. I can have a compass out of a child's toy if that's what I want and he's willing to sign it off. Ditto for most of the other instruments. Good point, Andy.....................maybe we can use one of the many altitude displays available. As you may have guessed, I removed the big dial altimeter about a year ago when I installed a transponder. I set field elevation on the SN10 which is on the first (custom) page and set-up to be displayed at twice normal height. When not otherwise being used I leave the black cursor on altitude.................works like a charm! Yes, my flight manual says I need an altimiter approved for use on certified aircraft, but it also says I must use the Prandtl tube, but I'm using a triple probe instead. The guy that's sign'n off my annual condition inspections doesn't sweat the little stuff. JJ > > Alas, yes they both require old fashioned dial altimiters. With todays > > glass cockpits, I'm wondering if this requirement isn't outdated? [quoted text clipped - 11 lines] > > Andy > Transponders give Flight Level (assuming they are working properly), so > will give the altitude ATC are intereted in. That's how they know what > FL you are at when not talking to them. There are places in the world where airspace structure is pretty complex and where you must know your QNH altitude to stay clear of airspaces, regardless of ATC. All kinds of good ideas. You may want to consider installing an EFIS. The Dynon D10A fits in an 80mm hole. You get the full six pack plus! It has an altimeter, airspeed, vertical speed, DG, T&B, attitude, OAT, true airspeed, compass, HSI, and angle of attack. If you have a little more panel room, you could consider an MGL Engima EFIS. It has a larger screen and all of the above plus GPS and a moving map display. The nice thing about the MGL is that it can display 9 different screens - that you can create and edit yourself. Now you can create the moving map display with airspeed and angle of attack on the left, altimeter and vertical speed on the right, and compass at the bottom. If you're doing a wave flight and get caught in clouds or want to file IFR, select another screen that has the six pack in the upper left, an HSI in the upper right, and a moving map display on the lower half. Both units supply altitude encoding for a transponder. Also they weight less than the instruments they replace. The Dynon has the option of installing an internal backup battery that will run the system for two hours. The MGL supports an external backup battery. A small 2AH battery would run it for two hours. If you want to take a look, the link to Dynon is http://dynonavionics.com/docs/D10A_intro.html. The link to MGL is http://www.mglavionics.com/html/enigma.html. Charlie |
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