skippydiesel

"Spy -In-The- Sky" I have heard some use drones😈

Not at all. A turbocharges mechanical wastegate performs as I have described. I merely speculated that it may have a ceiling limit (I don't know what that night be). Knowing that the naturally aspirated 912 ,can (with the right airframe) get into the mid teen altitudes, I further speculate that a turbocharged varient, with a mechanical wastegate, may get to 20,000ft (again I don't know). I suspect that few small aircraft pilots are intersted in cruising at altitudes requiring O2 supplementation. This may change for plots wishing to cross the high mountain ranges of the World. So logical speculation; For pilots who are looking for enhanced (115hp) sea level performance up to at say 12,000ft - turbo with mechanical wastegate may be quite acceptable and attract a lower acquisition cost. For those few pilots who want to top Mt Everest etc the TCU may be an attractive proposition along with pressure suite & O2 -$$$$$$$$ I am not trying to "prove anyone wrong" just asking for an answer to a question - Why does the carburetted Rotax 914 have a sophisticated/complex TCU, when its highly likly a mechanical wastegate would have done the job - Yet to get an informed response 😈

"Think of the simple basic diaphragm type waste gate actuator in this way, on one side we have boost pressure, on the other there is a spring and ATMOSPHERIC pressure. I don't think this will work correctly at altitude." Simplicity does not necessarily equate with inefficiency or lack of precision. Humans have along history of overcomplicating solutions. No offence, you are clearly wrong - a mechanical wastegate will adjust inlet pressures, as atmospheric pressure reduces/increases. The question really comes down to the precision and range of the mechanical wastegate V TCU. It would seem that at least two of the 912 aftermarket turbo upgrade suppliers, use a mechanical wastegate. I assume that in this, their product is successful/reliable. If it isn't they would have gone out of business very quickly. "Recently I removed a turbocharged engine and all components from a Cessna 414. The wastegate is operated by regulated engine oil pressure. Why did they go with this complicated system and not a simple wastegate gate. It is called an absolute controller, designed to work at altitude. " Sorry cant comment - don't know what is meant by ".... wastegate is operated by regulated engine oil pressure" in this context. One would certainly hope that in going with "... this complicated system and not a simple wastegate gate. " they achieved some benefit over a mechanical system. It may be that an aircraft turbo system having to perform over such a large atmospheric pressure range, eg sea level to 35,000ft, the mechanical may not be able to equal the TCU In this speculation, I would still wonder why Rotax didnt offer a cheaper mechanical option, with say a 20,000ft ceiling.😈

Not so much "dismissed" as poked holes in Rotax doctrine. Detonation in diesel engines -Good question. Your first to articulate a possible problem with my argument. By definition the diesel compression ignition is a detonation - that is the principal reason why diesel are built to more rugged (heavy) specifications, than petrol spark ignition, lower compression engines. Diaphragm actuators - No expert but would expect that they only operate between certain parameters, in this context atmospheric pressure. Climb (function) to 16,000' - As above - I don't know. The naturally aspirated 912 carburettors (diaphragms) are, I have heard, operating at their efficient limit at about 8,000' - obviously they can go much higher however the air:fuel ratio may be increasingly outside optimum. Speculation - Given the ability of the naturally aspirated engine to get into the pilot O2 levels, I would expect the turbo varient with mechanical wastegate to achieve at least 16,000' Turbo charged engines without wastegates - In my experince such engines are operating at quite low boost pressures ie the turbo is small and the inlet/ignition pressures generated are within the structural capacity of the engine . Speculation - engines of this type are most often found in constant rpm service eg hydraulic pumps/ generators, etc where peak rpm/performance is a near constant. Wastegate The wastegates overriding function is to to prevent over boost, while maintaining sufficient inlet pressure for optimum (?) performance throughout the rpm range. Over boost is likly to cause severe fuel detonation, excessive heat and combustion pressures, which will destroy the engine. In an aircraft the wastegate also acts to maintain the ability of the turbo to deliver required "boost" as the atmosphere thins at altitude. This boost can be to maintain sea level air density to the combustion process (turbo normalised), and above sea level pressure (increased power/"Boosted", as in 80 hp delivering 115 hp. .

As I understand it the Rotax 914 is a 30 year old design - the ECU or in the case of the 914 a Turbo Control Unit (TCU) was in its infancy back then. Computer controlled electronic injected fuel delivery was still a long way from the every car/motorcycle/even ride on lawn mowers that we have today. What I don't understand is why a TCU, when mechanical wastegate turbo pressure control, was at the time, a mature technological concept.😈

"The benefits outweigh the negatives and any risk can be mitigated. " When you start to talk about fitting such gadgets as auto/electric trim, autopilot, to light aircraft ( 600kg MTO? ) navigation/landing lights to VFR only aircraft, etc. I think it fair to say that for the most part thats exactly what they are, gadgets/bling - they do little if anything to enhance the aircrafts flying characteristics or the skill of the pilot and may increase risk. So the "benefits " are really in the aspiration (mind) of the pilot/builder. The increased risk & cost, is overshadowed by the want, as there is clearly little, to no need. Who am I to stand in the way of their enjoyment/aspirations. All I ask - please do not fly your "enhanced" aircraft over my house 🥺. 😈

Further thoughts; My oil cooler is in the cowling exit air stream, so potential for delivering contaminated air, especially leaking exhaust CO, also leaking oil & fuel. Coolant radiator is front of cowling taking in fresh air - safer, possibly less noisy BUT longer ducting .😈

Absolutly your choice. I have flown VH & now RAA - little "adjustments" are common & I doubt approved. If all care is taken and a bit of engineer/common sense applied ............. As for 19/Exp - thats the beauty of going down this track - whatever mods/personalisation suit you. I would strongly advise doing the research BEFOR getting on the tools. 😈

True!

Please state the "obvious"😈

You miss my point - you said "I cannot touch it" Literally: If course you can touch it - you do, every time you operate the flaps. I take this to mean, you feel you will be committing some sort of crime, if you do a non factory / authorised modification. I merely pointed out you can do it and the only repercussion is likly to be incurred, if the aircraft is involved in an incident. Then your dastardly deed may be discovered and you maybe sanctioned. The sanction may be severe if the modification was found to be a contributor to the incident. My bet - there are lots of aircraft flying aground, with a little mod or several, that have not been authorised.😈

Correction: You can "touch it" BUT this may have negative ramifications, should the aircraft be involved in an accident😈

I stand to be corrected; "Rotax 914 is watching only 7 channels that are needed to monitor the engine. 1,RPM, this is obvious. It also records this and reports overspeed events. 2,Throttle position, a key element to know for the MAP readings. 3,Ambient pressure is another, this is needed to know the delta to the pressure within the charge air (airbox pressure) 4,airbox pressure is another and this has limits for reasons such as avoiding detonation. 5, time stamp, important to track events for failures and diagnostics. The chip will hold lifetime of peak events (such as overboost events) with a timestamp for example. It also tracks overspeed such as when you underload the prop and RPM exceeds the limits. Both overboost and overspeed will trigger alarms to the pilot via a lamp. Solid red for overboost, flashing red for overspeed, both are serious issues. Another lamp, orange, is a warning when a sensor shows failure or out of range as in over temp of the airbox. 6, servo position is also tracked to know if your control is functioning correctly with the MAP you are seeing. 7, boost time is recorded and events that are over limits are recorded in the event of a failure for diagnostics. 8, airbox temperature. This one is super important as high temps lead to detonation. A type 914 can operate without a intercooler however it is limited to a max of 90C air box temperature. Should it exceed that the TCU will back off the boost to save the engine from failure. There is a timer on the amount of boost pressure for the same reason, 5 mins max at WOT and 41 inch HG, over that it will back off. In addition this chip holds the lifetime peaks and also the last few hours of full data for all channels. That is a rolling memory however and it over writes the old data as you fly leaving only the peak values. (timestamped to the TCU from first use)" From Rotax Owners Forum

In fairly recent times (10-15 years) turbo charged ground dwelling engines, have had their inlet pressure regulated by engine computer management (ECU). Before the ECU turbo pressure was regulated by a simple mechanical system, the wastegate. The wastegate is a fairly simple and trouble free system that, for the most part, operates without driver/operator input - KISS! Dont know how long the Rotax 914 has been around but it has a ECU managed turbo pressure system - why? Before 914 supporters jump down my neck on this, I should say I support the improvements to power, efficiency and pollution reduction, that the ECU management of fuel injected/turbo charged engines has delivered BUT The 914 is a carburetted engine ie the ECU has little ability for direct control the fuel input side of the engines performance, unlike an fuel injected engine. AND The aftermarket turbo conversions of Rotax 912 (carburetted versions) seem to use the tried and true mechanical wastegate turbo pressure control system. My question is; What significant benefit does the ECU bring to the Rotax 914 that a simple (lower cost?) wastegate could not do almost as well??? 😈

Hi Lyndon, i suspect that to prewire or not is entirely a decision for you. As for shielded wire - LED aircraft light suppliers would be your best informer. In the past (old tech?) I have read of light systems that caused radio interference. Three questions for you; Why 5 wires? Why do you think you might add lights at a later date? What is the aircraft? 😈

Hi Jason, What of noise ? ie does engine noise increase markedly when hot air duct open? Have you flown in rain? Does rain water come in with hot air? What size is and from where did you source, your ducting, radiator air scoop, & hot air valve? 😈

The thermal pants may be the way to go - my upper body never seemed to get cold. Potential down side is - getting hot & sweaty when I get out of the aircraft. I suppose I could just strip off the leggings - may cause a deal of amusement 😈

The only car I know/have expertise of, that uses exhaust heat is the old VW Beetle -they could kill you. To the best of my knowledge, all post WW@2 liquid cooled enclosed vehicles (car & trucks) - use a small heat exchanger/radiator + fan & ducting to circulate the hot air. They all had a regulating temperature/flow valve OFF - Full On. Most, if not all, also had air direction & fresh/cabin circulation controls. Modern cars use the same system, fancied up with such necessary & unasked for gizmos like "climate control"😈

I froze a few times, winter just gone. The unpleasant experience (mainly lower legs & feet) has got me thinking about possible comfort strategies. I did purchase, a bit late in the season, some of those chemical toe/foot warmers - so have yet to try them. The luxury alternative is a cockpit heater. Seems to me there are three options for heating the cockpit; Traditional; well proven heat from exhaust system. This should be a light weight, almost instantaneous (on start up) heat source. Unfortunatly comes with significant complexity (ducting) hole(s) in the firewall, increased noise when hot air vent open and the ever present possibility of CO poisoning. Coolant (Rotax); Seems quite a few Rotax powered light aircraft have automotive style cockpit heat courtesy of a small heat exchanger & fan forced air circulation. Much reduced chance of CO poisoning, no increased noise, smaller firewall penetrations. Down sides are, slower to deliver the warmth & additional weight. Users claim little to no impact on engine coolant temperatures. Oil; Dont know of any aircraft using an oil cooler/heat exchanger in the cockpit. May deliver similar benefits as coolant system. Down sides similar to coolant, probably increased chance of oil system failure. While a Rotax can continue to a safe landing with diminished/nil coolant, it wont get far with no oil. I welcome criticism of the above points and any additional thoughts you may have on the pros/cons of cabin heat. Despite my desire to follow the KISS principals in all things aviation sometimes one must be pragmatic - I have started to plan for the possible future installation of a coolant heating system. I hope to hear from Forum members on; What they have in their aircraft, the advantages/disadvantages.???? If fitted a coolant heating system - does it work, how well, what would they do differently, where did the source the components, etc etc????? I look forward to some great suggestions & 😈

Is it not a truism that insurance policies, of any kind, are worded so that should the incident/policy holder stray from the strict conditions of the policy, a claim may be denied in whole or part? The Forum members can debate this for ever and will never know the actual result (payment in whole, part or denied) until making a claim.😈

Looks like thistles, what of the blackberry etc?😈

You just enjoy arguing😁 Absolutely! but not without some kernel of truth/fact. You missed that I agreed with you. I accept your apology - not for insulting me (which clearly did not happen) but for your failure to take on board my actual comments😈

Landing pad (over hill) may be wider than taxi way? By the look of the tree covered mountains/slopes, looks to be a high rainfall area (tropics/PNG?) - sealed runway to be independent of rain soaked grass? Hard to judge, runway sloped up hill, not just at the beginning/landing direction but the whole way? Very little wind, but sock suggesting tail wind landing, which would indicate significant up slope - possibly a one way trip?😈

Thankfully, none of these issues apply to me. I have no intention of flying much above 10,000ft in my Rotax powered chariot😈

Back to oil pressure/flow at high altitudes; From Rotax Owners Forum; "The oil tank pressure is relative to the atmospheric pressure. The incoming pressure that drives the oil from the crankcase, from blow-by gas pushing into the crankcase by normal ring leakage, will always keep the pressure over the oil in the tank just slightly higher than ambient. There is always some light pressure in the top of the oil tank that requires venting. In regards to very high altitude this causes oil pressure drop relative to standard oil pressures you see at or near sea level. High altitude drones sometimes use a device on the oil vent line to trap some of this venting air to keep oil pressures in a more normal range. These are switched on (I have not seen an automatic one as yet) starting around 20 to 25k MSL. This maintains the pressure over the oil in the tank to flow better and you see it in less drop of oil pressure compared to without such a device. The one i am thinking of maintains about 5 psi in the oil tank over ambient." 😈