A64Pilot

I try to tell this whenever it comes up, but try going rapidly to full power on short final with the trim full up, if you have the strength and are comfortable with the excess pressure required to keep from stalling, fine. Maybe it should be done at altitude. If nothing else I think it should be done so pilots see just how much pressure is required, if you don’t expect it, it could catch you off guard. Ray Maule used to teach an approach in a Maule trimmed full nose up, I did a go around once and that was the last time I landed trimmed full up, it took both hands to hold the nose down, obviously I didn’t die, Mooney especially a 4 cyl one ought to be more forgiving

IF it were rebalanced when the servo was installed it should be a little nose heavy, which is conservative for flutter

Mine does anyway, always thought if it faced backwards that the icing mast wouldn’t be needed

Blocking a vent should not change level indication, unless and this would be an extreme event but unless it was blocked and over time the pump pumping fuel out pulled such a vacuum that it collapsed the bladders. I have seen a metal fuel tank crushed from a blocked vent though so it can happen.

Yeah all of our dealers kept trying to say that what they could sell was a 400 gl airplane, thinking of course 20% less capacity = 20% less cost. But that wasn’t the case the money saved in fiberglass in the hopper was trivial, money difference between a -15 (680 HP) Pratt and a -34 (750 HP) wasn’t much, a Hartzell three blade is a Hartzell 3 blade cost wise, batteries, Starter / Generator, airframe, wings, landing gear etc are the same, there just isn’t any real savings. But you could get a Factory overhauled Walter 750 HP for about half the cost of a Pratt, the Avia prop was less, the Starter / Generator came with the engine etc. Now the Walter wasn’t as powerful as a Pratt, but I was going to derate it to 680 HP as it could make that, leave the airconditioner off as well as lights etc and a 400 gl airplane became viable, then GE bought Walter and killed that plan, but GE was building a “New” Walter making much more power, no hot end insp, no fuel nozzles to clean and several other things and they were wanting to get this new engine in new aircraft of course so we became their launch customer. I think GE General Aviation died on the vine, nobody else jumped on the engine, they designed and built a new engine with 3D printed parts and 21st Century GE aero technology etc for the Cessna Denali. But where is the Denali? Pratt also began giving sweet heart deals to manufacturers to block GE too, but our current owner was too arrogant and stupid to listen. Point I’m making is I don’t see the price point changing. I believe the street price of a Pratt -34 is about $500,000, OEM was about $350,000 back then, but then you buy prop, prop governor, starter / generator, even engine mounts are thousands, so an OEM ends up with half a mil in the engine, so I’d guess you would need a million five to turn a profit for a non pressurized four place? You know I wouldn’t be surprised if a Turboprop isn’t as expensive as a Williams Turbofan, and who wouldn’t want a Jet over a Turboprop? Transition wise a Turboprop is much easier than a piston to manage, especially a Turbo, if FADEC there really isn’t anything to manage. You have to be stupid to hurt a Pratt, they start so easily you have to be stupid to hot start one. But yeah, money is the problem, and a 680 HP Pratt airplane just isn’t much cheaper than a larger higher HP one, Everything is the same, same Avionics etc, just bigger airframe. A TBM is likely about as small as a Turbine makes sense, and a Bonanza is about as big as a single engine piston makes sense. Now if a 500 SHP turbine cost half as much as a 1,000 SHP one did, then you could do it.

Usually VNE is pretty easy to increase, especially if it’s flutter. The Thrush S2R was an R-1340 aircraft, it got a turbine conversion via an STC, when Fred Ayres bought the plant, he bought the STC and the the first factory built turbine Ag aircraft was born. It kept the same gross weight and speeds of course, but Ag pilots fill the hopper until they just barely make the trees at the end of the strip, they don’t care about weight so they sold like hot cakes. Overseas though they very often hold applicators to the POH and as there were a great many overseas sales, they needed higher limits Years later Fred thought he was going to get rich building a purpose built Cargo aircraft for Fed-ex, overextended himself and went broke, we bought the plant and after a couple of years I went about increasing gross weight and Airspeeds. It took a couple of years to establish ourselves, clean things up and get a good “book of business” etc. , until then we just didn’t have the funds for Certification projects On the S2R-H80 my first real “new” aircraft that was of course really just a modified S2R using the same airframe, landing gear etc I increased gross weight from 6,000 lbs to 10,500 and airspeed VNE from 160 mph to 196 and flap speed to higher than the original VNE. Other than testing and analysis to prove the margins were there there was not all that much actual structural redesign required, only thing needed to increase VNE other than testing of course was tightening up the balance limits some. Aircraft are very often Certified not to their actual limits, but to realistic and safe limits that the aircraft is capable of in its current form. For example I have no idea what the actual flight CG limits are on the S2R-H80, the forward limit we tested to about as nose heavy as we thought safe to prevent a nose over on a tail wheel aircraft and the aft was the amount of lead we could stuff into the weight box that was mounted as far aft as possible. Neither limit could possibly be approached under any loading condition possible in the aircraft as it is. So very often when you make big changes to an aircraft there is a lot of room in increasing limits and often it’s not much actual work required to do so, what the gotcha is being able to afford all the DER’s etc to jump through all the FAA hoops to get there, the aircraft mods are the cheap and easy part, they may take only 90 days, but Certification can take two years after you finish the aircraft. So what I’m saying is that I bet fuel, VNE and gross weight may be within the possibilities of increasing on a Mooney, all it takes is Money Maybe Although a Certified four pax turbine already exists, it was built and Certified over 50 years ago, just was never built. It would in my opinion be a better aircraft, but it is not an inexpensive aircraft to build. All it would take is Money https://www.aopa.org/news-and-media/all-news/2019/november/01/will-the-interceptor-400-only-live-twice

@PT20J I got you beat on the car story. It was a 1973 Ford F-250, during the first gas shortage My Father had saddle bag fuel tanks put on it because we were building a beach house in Fl and you could buy gas only on odd or even days based on your tag number and we couldn’t get home without the extra tanks, it had a fuel selector valve. Well he would run it out of course, switch tanks and grind the starter until it started, second starter I put on it I put a Holley electric fuel pump on it connected to the ignition, told him turn the key on and when the pump quit rattling, crank it, which worked fine, no more burning up the starter. A few years later the truck got older and became a Farm truck, it wasn’t maintained very well and I guess the oil bath air filter must have gotten dirty because one of the men had removed it who knows when. One day it backfired, carb caught fire, but I knew we were in trouble when I heard the pump start rattling and instantly we had a BIG fire, pump kept running until there wasn’t much left of the truck. I think it quit when the battery melted. Bad thing was it was parked real close to the house but I was able to drag it away with the tractor before it caught the house on fire.

I’ve had one and seen the results of another. ‘I set my C-85 on fire from overpriming, some C-85’s inject fuel into the cylinders, mine does into the throat of the carb. Anyway once I figured out I was on fire, full throttle and motor the starter in the idea of sucking the fire in. Line guy came and squirted it with dry chemical. There was some charring if the paint on the cowling but mostly smoked up, and of course the air filter was toast. Threw filter away after inspecting for damage, got in a cranked it up and flew it home. Second was was a Fuel injected Maule on floats at Jack Browns, as starting a float plane often has a greater sense of urgency because yiu could be being blown into trees or drifting down stream etc. They were showing the owner the flooded start procedure, intentionally flooding it. Well he burnt the Maule down to not much but a steel frame with floats. I think it depends on severity, if the airplane burns up and the engine gets so hot seals etc are melted then I believe they are considered toast, but are the renuildable or which if any parts can be re-used. ‘I’d call Lycomings help desk, but think unless they have criteria it’s going to be at the discretion of the A&P

Flush the system well, I mean really well. 5606 turns to syrup when it gets old in Summer temps and this Syrup turns to grease in cold weather, grease won’t pump well, pulling a Vacuum is likely the springy feel you have, and it will suck in air too. Consider changing to 83282 (Aeroshell 31) but there are other brands, it won’t turn to syrup when it gets old. It just a new synthetic replacement and it’s 100% miscible with 5606 with no issues. It’s been around for a long time so if it were going to be a problem we would have known decades ago

It’s called “Attitude flying” something I learned in helicopters and it works for everything. Basically it’s learning what attitude correlates for what airspeed. If your example you learn the 90 kt attitude and if the engine quits you adjust to that attitude the aircraft will end up at 90 kts allowing you to do other things like looking out for a place to land as opposed to chasing airspeed. It is also more efficient as in you will lose less altitude pitching to the correct angle of attack and staying there than if you pull the nose up to slow to 90 kts then drop the nose to stay there. We had “bucket” airspeeds on the helicopter and I’m sure we do too on an airplane. basically if you graph the lift vs drag on a chart it will be bucket shaped and not a perfect one lowest point, on the helicopter 64 kts was lowest rate of descent in an autorotation and 94 kts gave max range in autorotation. Get slow though and you don’t have the extra energy speed gives you to swap for a low rate of descent for touchdown, and you won’t have the altitude to recover the speed, so don’t get slow until your sure you have the landing area made, it takes discipline to maintain that 90 kts, when the ground is coming up, but you need to. Long way of saying I guess that it’s better to be a little fast than a little slow

That’s what it ended up being on mine, but mine was intermittent, often just delayed coming down by several seconds and sometimes recycling the switch was it. My advice if you have the solenoids that look like starter solenoids as they are cheap and readily available, just go ahead and replace them and the switch that’s also cheap and inexpensive. Mine were 40 years old, why not start out with new stuff, reset that clock as it’s only an hour or two work and less than $100 to do so. Limit switches I don’t know how available they are, but if they are I probably ought to replace them too, nothing lasts forever.

Unlikely The system I’m speaking of is completely different than Googles, Goggles are of course on your head and use both eyes, the PNVS and TADS are those things on the nose of the Apache and are your eyes at night, but only your right eye. They don’t move as fast as your head, 60 degrees a sec if memory serves for TADS, faster for PNVS, but I’m sure that’s what the poster earlier was saying about clearing your tail, you spin your head around but the picture is still slewing when you stop because the system is slower, that can be disorienting and even make you sick to your stomach, you learn to not move your head faster than the system can skew. I’m better than 90% sure they weren’t on Googles, probably had them on their helmet but not using them, I’m pretty sure there is a currency requirement here so they had them to fulfill that currency requirement for the Staff Aviator, but Googles in an environment filled with bright lights just aren’t the best thing to have, bright lights, especially red ones bloom them out and shut them down both. I think they were there to check a currency block. I used to fly Staff Aviators from savannah Ga to Daytona at night so they could get their minimums and check the NVS currency block. Understand that in time of War the Staff is not part of a combat crew, will never fly a mission, truth is they will be working long hard hours doing their Staff job, planning getting you beans and bullets etc. Their jobs are important and critical, just it’s not being a Pilot. Need to understand that for the Female getting the Checkride, that flying wasn’t her Job, her Job was, well whatever she did in Politics etc. but as a Military Aviator she had minimums she had to fly in order to stay on flight status and receive flight pay as I assume a FAC 2 Aviator, line Pilots are FAC1, FAC 2 has lower minimums, and frankly much lower expectations for a Checkride etc. Then and this is going to tick someone off I’m sure but the truth is that the best pilots don’t get these kind of assignments. I’m speaking to the Warrant Officer here, the ones that do are the ones a unit Commander can afford to send and frankly the “Real” pilots don’t want to go, there is no real tactical flying, it’s just Ferrying VIP’s around, no yanking and banking down in the trees etc.

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.