A64Pilot

Many Experimental’s use Model airplane Servos for Autopilot and or trim

Maybe I do not know your compression ratio, and the bigger the cylinder the more likely detonation is, so my example should be conservative. Motorcycles can run very high compression ratios largely from modern combustion chambers but also because they have tiny cylinders compared to our motors An R-1340 is allowed to pull I believe 36” of boost from its Supercharger. It has again from memory a 6 to 1 compression ratio and it can do this on 87 Octane car gas. Now car gas and Aviation fuel Octane ratings are different, 100LL I believe if rated as car gas would be more than 100 Octane, likely the reason why we don’t just switch to 100 Octane unleaded race gas. It’s been around for years and I believe even higher than 100 Octane exists https://www.sunocoracefuels.com/fuels/fuel/ss-100 apparently as high as 109 https://racefuel.boostane.com/products/109-octane-fuel I do not know what your limit will be but am sure the actual limit will be higher than 25”. Then we are assuming 25” for 94UL, the 25” is very conservative and was I’m sure picked more for it being a number people can live with as most Big bore Continental bush pilots won’t cruise higher than 25 squared, but the ADI original STC’s were also established for Auto fuel, which I’d bet are lower Octane and more likely to detonate than 94UL. Will they find the actual limits and Certify for them? I doubt it because it raises the probability of failure and would cost time and money but doesn’t get them anything. Everything at this point is speculation

This says 6 GPH, if you carry 11 gls so you have just less than 2 hours, half that for the small tank https://www.avweb.com/features/the-return-of-anti-detonation-water-injection-adi/ But I’m sure of a few things 1. ADI flow rate surely is HP specific, meaning that I doubt a 300 HP and a 200 HP motor need the same. I think the flow rate they have is based on 300 HP as my C-210 was rated at 300 HP for 5 min and the STC back in the day was for bigger motored Cessna’s often in Alaska etc where 100LL is hard to get and stupid expensive, so car gas and ADI. So maybe it would be lower for lower HP motors or maybe they want to field a one size fits all kit? I think probably the latter at first. Original ADI STC was back in the 80’s when Auto fuel STC’s were common and cheap. Peterson used to charge $1 per HP of the motor for his Auto fuel STC 2. That 25MP and 400F is very conservative as there is no harm if it’s not needed and engine damage if it’s not on when needed so lean towards super conservative 3. All engines are not the same, some are much more likely to detonate than others, so the only way to come up with blanket numbers is to test the worst case engine and use it’s limits, that’s the mose conservative and as the fluids cost is minuscule the best idea I think. ‘I think taking off in my case a sea level that I would need it for 5 or 6 Min as at 1000 FPM it takes 5 min to get to 5000ft where you only have 25 MP, but let’s use 10 min as a nice round number and for extra safety. 10 min consumes 1 gl even, I like whole numbers. That means I can get 11 takeoffs before I run out, so let’s use 10, if using the big tank, cut it down to 5 if using the small tank. I would use the small tank I don’t know about you but in my World 10 takeoffs is plenty even if the fluid isn’t available at FBO’s because at first I don’t think it will be.

I’m pretty sure that a “True” turbo has a much lower compression ratio than a Turbo normalized engine does as the purpose of a “True” turbo is to increase power not just maintain it like a normalized Turbo. So if I’m correct then your MP limit will be higher than 25” while a Turbo normalized engine might be 25”. Sorry but I have to beat this dead horse, that’s where ADI comes in, it will maintain your current MP limit as long as you don’t mind the ADI running, but one assumes that you wont cruise with it on, so your cruise limit ADI off might be lower than your now allowed. Running LOP will complicate things of course, but I wouldn’t expect it to be addressed in an ADI STC unless your POH allows LOP and has a procedure, then it might. The LOP is speculation on my part, whether or not ADI will allow full boost isn’t.

The list of fuels is also on the TCDS of course look under S2R-T34 I’d cut n past it but can’t a .pdf? If your curious also look under note 13 on the TCDS the aircraft was only Certified to 6,000 lbs but I believe CAM 8 allows a 31% overload if flight tested and it has the performance to do so, note 13 allows operation in the Restricted Category increase from 6,000 lbs to 8,500 lbs. The S2R-T34 is also the only dual Category Ag plane Certified in both the Normal and Restricted Category. Story is some wealthy person that lived in an Airpark in Colorado I believe bought one as a toy, well his neighbors got their nose bent on there being an Ag plane on their exclusive Airpark and the Home Owner Association ruled that only Normal Category aircraft were allowed, so the guy paid Fred to have it Certified in the Normal Category. There are two sections in the POH, one for Restricted and a separate for Normal. It can’t be Certified in Utility because No Thrush has ever been officially spin tested, for an aircraft that’s mission is that close to the ground there is no point, and apparently the FAA agreed. I’ve been told that they recover from a spin better than most though, I suspicion it’s because of the huge rudder, but I have never spun one myself. They don’t roll well though, you would think they would as they have a very high initial roll rate, but after about 90 degrees roll dampening kicks in a the roll rate past about that does not accelerate so they roll slow. People have a hard time understanding this but they are not an aerobatic aircraft, it’s best to think of them as heavily loaded trucks. What other aircraft has a useful load exceeding its empty weight?

I retired from Thrush I think 2017, because I could see the Bankruptcy coming and didn’t want to be around for that. So no, but if you really want one call parts they should still have them for sale, it should also be in the placard section of the old POH’s We used to have them online for free, don’t know about now I Certified just about all the Thrush models as new Aircraft increasing gross weight and V speeds etc. and in the new Certs we dropped the alternative fuels as they all came with disadvantages, Avgas built up lead on the turbines causing hot spots and possibly balance issues, Home heating oil varnished up the injectors causing them to “streak” instead of a fine spray and that caused hot spots unless you cleaned them much more frequently, and the Diesel that was Certified no longer exists. Pratt still allows Avgas as an Emergency fuel so I sometimes had to do a Hot fuel test with 100LL, as we had no use for it I got a free couple hundred gls of Avgas after the test. I only had to do the test on one Model, the S2R-T660, the Worlds only FAR 23 Ag plane, maybe because it was part 23 I don’t know. I learned early on unless you were going to contest it, don’t ask the FAA why. Just do it, that gave you credit if you will that you could cash in on a test you didn’t want to do. We think that aircraft Certification is a list of flat ass rules you must comply with but in truth it’s a negotiation, lots of give and take, of course many you must do, but for example in the Thrush we didn’t test for head injury criteria. We require a helmet and instead of 1,500 lb three point belts we had a 5,000 lb four point (5 point on the S2R-H80) between the harness and it being stronger and wearing a helmet I think we were safer and the FAA agreed.

Yeah Fred did that under Marketing pressure as many operators wouldn’t go turbine because of the cost, Thrush was the first Ag turbine aircraft. Diesel, home heating fuel etc was much less than Jet, but not anymore. There are Farmers now that have their own Ag planes burning Jet in their Tractors because Jet is so much cheaper than off road ULSD, so it’s a complete flip. Jet having such a high sulphur content I suspect may be even kinder on the fuel pumps and injectors, when ULSD came out it caused premature wear in many Diesel fuel injection systems, just as unleaded car gas caused valve recession. ‘Both new fuels caused engine design changes. I’m suspect that any unleaded fuel won’t, without an additive to prevent it, hopefully as we don’t have any emissions controls such an additive can be put in the fuel.

I’ll throw this out just as a thought. Thrush many years ago Certified their Turbines to burn Diesel as Diesel was very similar to Jet, but much cheaper. Well nobody burns Diesel anymore because Jet-A is much cheaper than ULSD, even off-road ULSD So why didn’t Jet-A increase in price by the same amount that ULSD did? I’m not saying your wrong with Refineries, you obviously have way more knowledge than I do, I just suspect that anytime something is created to be environmentally friendly it seems to be overpriced. Take California Gasoline for example, average gas cost in the US is $3.16, yet the California special blend is $4.89. https://gasprices.aaa.com/state-gas-price-averages/ Yes we all want to point to taxes but I think that’s not it, it’s the special blend California requires. I suspect that it doesn’t cost more than 50C a gl for the special blend. ‘From the below article “The CEC says the national average for state gas tax is 32 cents, and California is about 58 cents” I suspect there are other California only taxes but still it’s not near the more than $1.50 a gl https://www.cbsnews.com/sacramento/news/why-is-our-gas-expensive-california-breakdown/ All this is just to say that I suspect that while it may only cost $1 a gl for a special blend unleaded Av fuel to produce that we will pay way more than $1 a gl when or if it becomes available. Heck I bet UL94 will cost more than 100LL, but I hope by not much.

I’m sure your right, it just seems that over and over anything environmentally friendly is supposed to come at a minor cost and doesn’t or either isn’t actually environmentally friendly. We switched to R-134A years ago to save the Ozone layer, but it turns out that now it’s supposedly extraordinarily bad as a green house gas, 1,430 times as bad as CO2 HFC-134a: a Potent Greenhouse Gas Most common refrigerant used in MVAC systems since the 1990s. Potent greenhouse gas with a global warming potential that is 1,430 times that of CO2. Use of HFC-134a in MVAC systems accounts for an estimated 24% of total global HFC consumption. It is the most abundant HFC in the atmosphere. The restriction of HFC-134a will occur under a broader prohibition of any substances with a Global Warming Potential (GWP) higher than 150 in the MVAC sector. HFC-134a will no longer be allowed in nonroad vehicles as of January 1, 2028. Servicing of existing vehicles using HFC-134a with HFC-134a will not be impacted and will continue to be allowed. LED light bulbs it seems have arsenic and lead in them that makes them bad for the environment to throw them away Are LED light bulbs dangerous? Unlike other types of light bulbs, LED bulbs don’t contain mercury, but they do have small amounts of other hazardous substances such as arsenic and lead. Therefore, if you dispose of them with your regular household waste, these toxins can leach into the environment and make their way into the water table, so it’s important to dispose of them properly. It just seems to me that many things the Environmentalist cry that we must do to save the Earth it seems to be just as bad or often worse, and always seems to come with a special Environmental Tax.

Average Jet a sulphur content is 400-800 PPM, max allowed for ULSD is 15 PPM This study says it would only cost 5c a gl to reduce it to ULSD levels, so why does ULSD cost so much? https://lae.mit.edu/2024/06/28/study-released-on-the-costs-and-benefits-of-desulfurizing-jet-fuel/ When are the Environmentalist wake up to the Sulphur content of Jet? Why are they so concerned with 100LL? It’s a drop in the bucket.

Weighing thousands of lbs than their combat load too and probably a much reduced speed and climb rate, but we don’t have the excess power they do, and we can’t reduce the weight like they have done. Essentially at sea level we would be reduced to the power output that those that live at 5,000 ft live with, but we would perform better because while engine power is down we still have higher air density, cruise at or above 5,000 ft there would be no difference. Want to see what it would be like? T/O at 25” and adjust to maintain that until your full throttle. Yeah we could do it, but ever chart in the POH is invalid for T/O and below 5,000 ft. Back to we non turbo folks won’t lose any power with ADI on 94UL. They say it works fir the turbo folks too, but I have no specifics on that. We could go to unleaded fuel tomorrow, but for some reason the emphasis is on wanting a magic fuel that I maintain we don’t know what it will cost. Or a replacement engine that I do know ballpark what that will cost, more than I paid for my J model. Every environmentally friendly fuel has cost more, back in the 70’s when first introduced UL car gas was much higher that’s why so many mis fueled their cars, and Diesel used to cost far less than gas, but ULSD came along in 2006 and it’s $1 a gl more than gasoline. So just taking the sulphur out of Diesel cost about $1.50 a gl. Ever looked to see how much sulphur Jet has? What’s it going to cost to go to low sulphur jet? There is I’m sure at least thousands of times mor Jet burned than 100LL. 94UL in widespread use should cost less than 100LL, but I bet it won’t but if it’s the same I can live with that. I think in my opinion it’s become pretty clear that the GAMI fuel as currently formulated isn’t the answer that was hoped for, it could turn out far worse than the Mobil 1 oil problem. Personally I’m astonished it’s still being sold, Cirrus has said they are concerned about the airworthiness of their aircraft that have used it, and the FAA usually listens to manufacturers. If a Cirrus suffers a structural failure there is going to be hell to pay, I know nothing about Cirrus but if it’s made like I think the tanks are part of the wing structure, if they get compromised, so is the wing. But then I think if the current administration gets wind of what’s going on, we won’t have to worry about 100 LL going away for at least four years, beyond that? Who knows.

Yes, absolutely, the reason Diesels don’t detonate themselves to death because Jet and Diesel is very low octane is that there isn’t any fuel there, once running combustion in a Diesel begins arguably the moment fuel is introduced, this is what constrains the RPM on a Diesel as the higher the RPM the less time you have to complete injection. So enter Mazda with their spark controlled compression ignition gasoline engine, even though it’s compression ignition it doesn’t detonate, I believe it has arguably essentially a Diesel’s common rail injection system and injecting fuel directly in the cylinder at the precise moment burn should begin, mimicking a Diesel. So yes obviously very high compression gasoline engines are possible running on 87 Octane or lower car gas, but of course that’s an entirely new engine to certify. https://www.mazdausa.com/discover/what-you-need-to-know-about-the-compression-ignition-engine https://www.caranddriver.com/news/a15339942/mazdas-gasoline-skyactiv-x-spcci-engine-explained/

Yeah the system got a lot of guys, especially the older more experienced ones. When you got out of the aircraft at night you were pretty much blind, your right eye wasn’t night adapted and because you had been ignoring your left for the last couple of hours often the brain just wouldn’t use it, you had to learn to close your right eye to force the brain to look out of the night adapted left eye. For me what was hard was that if you looked to the right your right eye was 10 ft forward and three ft lower than your left and lights especially would show in the combiner lens in a completely different spot than the thermal image. As you gained experience your brain would automatically switch from one eye to the other, left for inside the cockpit, right for outside, but until you got more experience with it it would make mistakes. I was riding in the front seat which used the TADS for night flying, TADS could look straight down. Anyway I dropped my pencil and looked down to get it, but saw trees very close rushing by at high speed, scared the stew out of me, thought we were crashing or something, brain had switched back to right eye. It screwed up some people so bad that if you turned the light out in a room they would fall down, that was temporary though it seemed.

We could probably do it using FLIR, our HMD had all the symbology necessary to fly IMC, but our mission just in truth had no use for IMC, in Wx a helicopter is nothing but a slow moving very easy target for ADA. Our only real use for IMC was for recovery if you inadvertently went IMC which could happen easily at night, but as we had no real range and nothing close to a Combat area is going to have an approach our only real hope was to have Terp’d out a recovery approach using GPS, but even then if you go inadvertent IMC in a helicopter the likelyhood of having Wx that you could break out in an approach is almost zero. I did once hover down thru a ceiling using Symbology generated off of the HARS and doppler RADAR, essentially we could come to a hover “drop” an eight sided symbol in symbology and if you stayed in the box slowly descend, slowly to avoid settling with power. But hovering IMC is difficult, you couldn’t do it without a computer assisting in stability

Normally if you heat a fluid it becomes more reactive, that is it accelerates corrosion significantly when hot. So if car antifreeze was corrosive surely given a couple of decades it would destroy modern aluminum Auto engines and especially radiators as they are thin walled? Last Summer my 2005 Mazda Speed Miata radiator started leaking, the seals on the plastic tanks were why, it’s common on old Miata’s. Anyway I looked inside the aluminum radiator, the metal was just as bright and clean as the new radiator was, so no corrosion at all in 19 years. I do flush and change coolant every three years, probably excessive, but cheap and easy to do. But it seems that at least the old Prestone green isn’t corrosive to aluminum?

There is a small Pratt PT-6 that I think would be better. The Baby Allison was designed for the US Army to be used in either a fixed wing or Rotary wing scout. PT6-21, Bill Hatfield does a C-206 conversion with one, plus there are shed loads of used -21’s available, which is the most important part of a turbine conversion (affordable engines) Old King Air engine, I think 550 SHP, but you derate it, derating keeps power way up high and adds mucho life to an engine too https://turbineconversions.com/conversions/turbine-206-cessna/ So far in our history it takes Government bucks to fund engine development, I believe the small jets only exist because they essentially use cruise missile engines? Maybe the Government will pay for a baby turbo prop to be developed for drones, just based on the Ukraine war it’s my belief that the future will see way more drones than we see now, way more, the Terminator is closer than we think. It’s been my belief that the day of the manned fighter ended last Century just too many in the AirForce don’t want to see the end of it. I base that on conversations I had at the Edwards O club with pilots that were doing Air to Air testing against a very rudimentary remotely piloted vehicle. They said you got two turns, the first at the merge when “fights on” and you got killed in the second turn every time. An unmanned aircraft has an unbelievable maneuverability whereas any manned modern fighter I believe the pilot is what drives the maneuverability limit. This is what they were flying against, it was just essentially an FPV drone, it wasn’t very advanced, yet it ate manned fighters lunch. https://en.wikipedia.org/wiki/McDonnell_Douglas_X-36

I seriously doubt any post WWII era test pilot would dive until flutter onset, reason is sometimes flutter can completely destroy an aircraft almost instantly. The WWII era guys were very brave or very foolish, many didn’t survive. When Rockwell Commander was doing a VD test flight of the 112 the aircraft disintegrated, they recreated the event in NASA’s wind tunnel and the time frame from flutter onset to complete disintegration was less than 1 sec. I really wouldn’t want an aircraft to disintegrate on me https://asn.flightsafety.org/wikibase/2731

Flutter is just one driver of VNE, there are many others, hopefully if well designed flutter isn’t even remotely close to VNE. Crop duster I built had an over 100 kt flutter margin, reason is that over the years flight control surfaces gain weight from painting and repairs and even insect nests and as the majority of the surface is behind the hinge line over the years if not rebalanced you lose flutter margin, therefore in my opinion while not required a responsible manufacturer designs for a large flutter margin. Engine failure concerned me, flutter scares me. Crop Dusters are I believe much worse with owner repairs than most GA aircraft so it was prudent to take that consideration into the design. I even had owners changing the wing angle of incidence of both the wing and tail. I know this because several told me they did and were trying to get me to incorporate their “improvements” Some other drivers are gust loading and even windshield structure, several others that don’t come immediately to mind as I am no Engineer, but structure and aerodynamics both drive VNE, but in a Velocity Dive test it’s flutter in most cases that your validating, and on light aircraft that VD test is the most hazardous requiring a parachute, boots being worn and a chase plane etc. I had a door quick release installed when I did one. I misspoke about flutter being IAS, but point is without any analysis I believe the Mooney tail has enough margins for a Turbine installation. I base that on my belief that if it didn’t then over the years there would be several accidents of Mooney’s losing their tails and I don’t believe there has been. You can test forever but the actual acid test is a fleet with years of operation. I agree that having the whole empennage being hinged like it is, is weaker than if it were one piece, but apparently it’s strong enough. Mooney’s of course have their issues, all aircraft are compromises, just structure doesn't seem to be one of Mooney’s weak links. I just don’t think the market exists for a small four pax non pressurized turbine myself, in truth it seems the market doesn’t exist for a 4 pax piston complex aircraft.

Re Cirrus, I would be afraid that paint is the least of their worries. What made the Cirrus leak? They don’t have bladders do they? I assumed the tanks were integral? More often than not anything that dissolves Jet-Glo will also dissolve composites, although I don’t know with what or how a Cirrus is made. I would assume prepeg and an Autoclave, but as they don’t interest me I haven’t looked. I know only some paint remover can be used to remove paint on boats, some will dissolve even Epoxy boats, so fiberglass safe remover has to be used or way more common mechanical removal Epoxy boats are ALL painted, you can’t Gelcoat epoxy, not sure why

I don’t know of a less than 300 HP turbine, the old Allison now Rolls baby turbine was 317 SHP, but very quickly grew to 420 SHP and now is much higher We got 2.5 hours with reserve from them in the OH-58 helicopters that held 71.5 gls of fuel The best use of turbines in airplanes is to hugely derate them, the TBM’s for example have cores capable of 1700 SHP but are derated to about half that, that means they can make rated power way up high which of course means speed. It also means smaller and lighter gearboxes etc. From a flutter margin etc that’s indicated airspeed, so if we can assume a Mooney would be good for 250 kts, then that has to be over 400 up high, but I have not done that math I do agree that an unpressurized turbine is likely to not be very desirable. A bigger problem as I see it is cost a turbine STC would likely cost way more than even a newer Mooney is worth.

Tones would be obnoxious as you would be listening to them for half the time you were spraying, depending on length of the field your turning about half the time.

I know very little about TKS myself, but these guys claim that unlike ground de-icings, TKS isn’t corrosive. I didn’t think the ground stuff was either https://www.cav-systems.com/tks/

I didn’t think it logical myself, but more than one inspector told me it, it even got one of my inspectors worried at the plant. I finally told him that not trying to be ugly but he’s not getting sued, he doesn’t have enough assets to even whet a Lawyers appetite, he still worried though

I think maybe the best use of a concentrator is to use it well before you’re required to be on O2. If your older you might want to use it even under 10K, and if flying at night 6K. I think if you do you will find your less fatigued and at night it really improves night vision substantially

Army Aviators as a general rule don’t do IMC well, only legal Nav we had for IMC was an ADF, and helicopters are negatively stable in all three axis. We trained in actual IMC in Huey’s in school but Attack anyway usually lost the skill over time. We had an IMC break up plan, we never flew formation IMC in truth I don’t see how it’s possible, I’ve been IMC where I couldn’t see my own wing tips. They usually pushed Wx harder than they should. I got in the habit at Ft Hood of just committing to IMC and getting down via the GCA approach Nowhere else I was stationed had a GCA approach though