Blue on Top

@aviatoreb Erik: I believe that we agree . I agree with your numbers, too. The problem with that is HP is takeoff and climb performance (an "Ovation" will initially outperform an "Acclaim"), but the cruise speeds would be improved … especially if you don't mind going up. 2) Gotcha. 3) (not above … and I should start a new thread if I really want to talk about this) But you have made me think about a topic when 2 and 2 are added. I'm in the Experimental world a lot, too, but I don't remember people desiring a full-aircraft parachute there. So (and I'm thinking way too logical and not with my heart) why are parachutes needed on airplanes that have to prove reliability and structures and not on those airplanes that don't? Thanks for the great discussion, Ron

1) Diamond dropped the Mercedes many years ago and designed their own for their airplanes. The certificated horsepower is 170 HP. 2) I can be wrong and corrected (learn), but one can't just throw a different engine on a certificated airplane, label it "experimental" and then operate it in the normal category. I have heard of people getting away with it for a year, but there are restrictions on operations (passengers, etc.). Along those lines, I am (educated) guessing that those airplanes are put in the "experimental", "market survey" category. Just a thought.

@aviatoreb Erik: I agree 100% on the drawing from other industries to save money. Chevrolet makes >1M crate engines a year; aircraft engine OEMs haven't made that many in the history of aviation. A crate vette engine is <$10K (and can burn autofuel with alcohol). Please explain how an automobile engine is more expensive (yes, there will be certification costs). Thanks!

@Stephen OMG!!! I'm in love … with the back half at least! I look and see so much drag, though . Awesome job in Photoshop!

@Austintatious No misunderstanding. Cars and airplanes are different … in many ways. The video (which is great btw) shows a car doing 200 mph on 700 HP. Our Mooneys do 200 mph on 200 HP. Although an airplane has a larger frontal area, airplane aerodynamic drag is significantly less than an automobile even with the penalty of drag due to lift. The automobile has profile drag, but it also has drag due to down force (to keep it attached to the road), friction in the wheel bearings and drag due to the ground being so close. The incremental drag added to an automobile for cooling is insignificant. It could double the drag of an airplane. Yes, we could add a massive radiator … at a significant weight penalty, and we could bring in massive amount of air and slow it down significantly, but all that adds drag, too. CHTs are for air cooling … and that is relatively much easier. with the high delta T. We're going to find solutions! BTW, @Yetti, I LOVE, LOVE, LOVE the DR-980 engine … and it's air cooled, too!

A) Twist is not a requirement; it is a compromise between cruise drag and stall characteristics (which can also be modified by other variables … like stall strips … which are also a compromise between stall characteristics and cruise drag). But, we'll continue on with "A)" is true. Yes, the tooling would have to be precise. Precision costs money but could be minimized if the tool was designed correctly. There must be some tolerance. A goal of engineers is to have as few parts and dimensions be critical and/or tight tolerance. C) Good question. Most likely yes in this case as aerodynamics are pretty tolerant of little changes (stall strip vertical position and laminar flow are exceptions). 1) Yes 2) Definitely 3) LOL. Sad but true. MS1) Hangar rash will definitely change aerodynamics, and here a little might mean a lot … or not (one has to know why, where and how much). For example while backing your airplane into the hangar, you hit an elevator or aileron on the roof support pole. Will it change the airplane? Yes. The surface will "float" to a different angle. Does it matter? That depends on the amount and direction the TE of the surface was bent. MS2) These installations are approved through FAA guidance, which is good and I am glad about it being easy. BUT (and this is not bragging, Don ), I know a bit more about the effect, and I'll limit the airplane operating envelope if applicable. MS3) Some airplanes are more tolerant of surface balance. In a Bonanza, this has proven fatal in some cases in the past. We write ICA manuals for a good reason … and they're not easy. Thanks, Ron

@PT20J Skip: So … we don't always say all we know? There's not enough time . Sure glad MooneySpace doesn't count these emojis ! Let's start with the basics. The stated airfoil on an airplane is typically the base or starting airfoil. If (when) a company modifies that airfoil, it probably won't tell the public (or anyone outside of that small design group); it's company (or even department) proprietary data. The airfoil is modified to produce a certain CLmax, Cm (pitching moment) and/or CDcruise for that airplane. In Advanced Design, the airfoil, wing planform, twist, dihedral, etc. are varied to produce the final wing (and expected coefficients). Although the M10 wing is physically straight tapered, it was designed to produce a perfect, elliptical lift distribution. So on the twist (and as you estimated), twist is typically input in whole degrees and then 0.5 degrees after we get close. Smaller increments are a waste of time. But, with the current desk top CAD and CFD programs, we can run many iterations in a day (Al and Art didn't have that luxury). In Al and Art's days, the twist was also linear. IOW, if a wing was twisted 2 degrees, it would be twisted 1 degree at half span, 0.5 degrees at 1/4 span, etc. You get the idea. With the speed and modeling capabilities we have today, we also tailor where twist occurs spanwise. For example, the wing may not have any twist in the flap section (much easier to manufacture the wing, flap, flap tracks and flap operating mechanisms) and have all the twist in the aileron section (smaller loads and smaller parts). Plus, we are only trying to protect stalling the aileron section (at the price of cruise drag). So, Cessna SE flap/aileron ratios are planform/manufacturing driven. As one can look at the larger Cessna SE airplanes where they tried to continue the flap into the outboard, tapered section, hence the flap becomes more of a "best" compromise solution. Higher percentage chord ailerons, especially with lower Rn (smaller tip chords), work the airflow harder and are more likely to separate at a lower aircraft AOA. I'll repeat an earlier warning, regulations do not require full and rapid aileron input at or near stall. As a direct result, there are airplanes that will depart controlled flight (stall with an incipient spin entry) without any stall warning. Good CFD departments today will analyze this condition in CFD to validate that the wing won't stall due to this flight control input. The tip of the iceberg has been exposed. Keep the Blue on Top -Ron

@Aerodon Thanks for the data, but … … ummmmmmmm … 25% of what? Similar to the internet, you can't believe everything that's displayed on your dash. (We had a rental car once with this displayed). The best I could figure out is that the car took the value of kinetic energy at the time brakes were applied (proportional to V^2) and then compared it to how much of that value was returned to the batteries. Locking up the brakes or not touching the brakes would give you a value of 0% (i.e. friction of the brakes or friction of the wheels and drag of the vehicle robbed the other portion of KE. The brake pads are there only if you need a deceleration greater than that which can be provided by removing electrical energy. All airplanes get the potential energy from losing altitude. Drag steals some of that energy, independent of propulsion device. If one wants to regen via a windmilling propeller on the way down, they can. Expect the glide ratio to go to zero, though, as a windmilling propeller creates a lot of drag..

For those wanting a marine engine converted and certificated, please add the weight of a gear box and the weight of a lake full of water so that we can compare weights apples to apples. IOW, a radiator is not the same of a lake full of 80 degree water. One of the problems of cooling a water cooled engine is the drag caused by cooling the water. Please consider the maximums water temperature coming out of the engine as at 210F. If the OAT (outside air temperature) is 120F (yes, in certification, that's the regulation), that gives us a temperature delta of 90 degrees. To get the 210F water temperature down to even 150F would take a very, very large and/or very, very thick radiator, and the air would have to be slowed down a lot to be able to transfer the heat out of the water. There's a ton of cooling drag slowing the air down that much. To the poster that mentioned the M10 (sorry for not remembering your name), replacing the diesel with something else is a great idea, but that was not our marching orders. 100% carbon fiber, Garmin and diesel at a cost below $XXX,XXX was. Ironically, cost of those 3 raw items alone are greater than $XXX,XXX.

@flyer338 Thanks for the real world example! This is also a great example of where pilots and aerodynamicists think differently. I'm hoping all y'all teach me enough guidance so that I do not upset the FAA and pilot organizations when I tell them that changing the AOA/chord line is really not how it works . As a pilot (and the FAA, currently … and I wear both those hats, too), it is being taught that when a flap or aileron goes down, it increases the angle of attack. Yes … and no. One could say that the LOCAL AOA has increased (but it is not proportional to the actual, physical new chord line (line drawn from the leading edge to the new trailing edge). The situation is simply not that simple. Allow me to clarify. Aerodynamicists plot a curve of local stall AOA (relative to a singular aircraft AOA) versus wing span location. In other words, at what aircraft AOA will that section of the wing stall. We design the wing through changing airfoils, thicknesses, chord lengths, twist, stall strips, etc. to have the wing stall progress from inboard to outboard (so the ailerons remain effective through the stall). I know that's a lot in a couple sentences. Basically, we think of the aircraft AOA required to stall that local area. Why? We only know/measure one, singular AOA that is measured locally and converted to the aircraft as a whole. If one thinks of a down aileron (or flap) as the AOA increasing, one is forgetting that the camber is also changing and/or a slot may be opening, etc. In other words, it's a different airfoil completely. We can agree that the wing is being asked to work harder in that area and will therefore stall at a lower angle of attack. Let the volleys begin PS. Bonus information: As a word of caution, current regulations do not require stall warning to give any warning before a departure initiated by the ailerons. Follow-on: A stall initiated the ailerons will develop into a spin (the down aileron causes asymmetric yaw .. the second ingredient required for a spin (the stall being the first)).

Thanks, @tmo. I agree with you on the fuel costs versus aviation fuel. Does an automotive fuel solution work for European countries? Although the total, full to-TBO/TBR-time costs may be lower with a diesel engine, the initial costs will not be, but that might be a good financial tradeoff (purchase price on business jets are a minor factor compared to hourly operating costs). Fuel is also heavier, but a tradeoff of less quantity could pay off too as less fuel is burned per hour. The Mercedes diesel was not designed to run at 100% power for long durations nor was the gearbox. TBR times on both of those are currently low, with the gearbox being half the time of the engine. A turbocharger is also required, which is also an issue when it goes. Depending on the diesel, there may not be enough power to maintain flight. Another failure mode that has to be accounted for. We need to keep looking for options. And kissing frogs. Thanks, Ron

Thank you, @Dan at S43. Great information! I was curious and thinking it might be a good idea, but your points are valid and make a lot of sense. Note: I'm trying to give you a compliment, but it's not sounding that way. Thanks again for the great, insider knowledge!

Yes. All up, including coolant and gearbox. Ready to fly … needing an STC for all certificated installations. Thanks!

As an update (~10 hours into this thread), thanks for all the great input! Keep it coming! 1) I'm surprised the aero gurus on here haven't complained about a water-cooled engine. Yes, it adds drag 2) I'll also come clean in that I know the person that headed the Toyota engine certification. He lives within a mile of me. (yes, certificated aviation is a really, really small world). It's not all roses ... nor is/was the Orenda engine. 3) I also have inside information on gear boxes (AutoPSRUs). He has been a good friend of mine for years. We trade stories often. The goal of this "study" is to see if we can produce power at a much lower cost than is the current industry standard. It will help all of us if flying were cheaper … and safer, too. Thanks!!!

@McMooney Thanks for the input! Not decided yet. Turbocharging has pros and cons (as all y'all have discussed here and abroad).

@thinwing Thanks! I thought they left the original horsepower. ???

@Igor_U Thank you! Again, saving emojis . 1) Very true. The person that headed the project lives down the street from me. Regretfully, a lot of people and companies have lost a lot of money $MM trying to certificate auto engines: Toyota, Orenda, etc. 2) True dat. On this the paperwork will exceed the weight of the engine. On a good note, it weighs a little less than an IO-540 or IO-550. Thank you!

@steingar Thank you! (I'm saving my emojis ) From experience, the diesels are VERY heavy, and they are not low cost! I'll leave it at that. I agree that certified aircraft engines do a great job at what they are designed to do. They are just too expensive because the OEMs can't make enough of them.

@bob865 Yes, but less horsepower (more torque), better installation and certificated. I bet his climbs like a homesick angel!

I agree with you, and I need to learn a lot more. We have data on this engine running at 100% for 2.5 - 3 years continuously (with breaks for oil changes only). This engine, unlike most automotive engines, is designed to run at full power … like an aircraft engine. Thanks! Ron

I added "LS7" to the search engine items. As @carusoam just pointed out, the BIGGEST hurdle that I see currently is defining a hard, non-changing configuration.

So, a friend has gotten me interested in looking at certificating the Chevrolet LS3 engine for airplanes (or one of the 4th generation LT engines). Looking into it, there are a lot of advantages. I am not afraid of the certification process. Thoughts? PS. Yes, I know about the Porsche engine/airplane (M20L)

I know that this should be a different thread, but … (okay, I'll do it right). Look for a new thread entitled, "LS3 - It's not just for Corvettes."

@tmo In a single word, "No." All of your logic is correct, and this solution would be less weight efficient as it would be significantly heavier and/or potentially more expensive, depending on what source is generating your electric power for propulsion. Now I'll take us outside the box to look at other efficiencies. When we get to the point we can carry enough stored energy to power the electric motor for 30 minutes, options open greatly. Instead of a $$$ Lycoming or Continental engine, we can put in an LS3 crate engine for <10% of the cost. If the LS3 quits (much less likely than a certificated aircraft engine), we have 30 minutes to get the airplane safely on the ground. Cost efficiency becomes much, much greater. Remember too that the first M20 had little more than half the horsepower of today's new airplanes (if the factory were open ) When we find a better energy storage/producer, our weight will decrease significantly, but the cost might go up significantly. It all depends on what one wants to optimize.

I love all the previous discussions … Yes, I went all the way back through the 2013 posts and attachments . Yes, I'm a total aero geek. So, all the previous discussion is very typical of everyone talking about stalls, spins and spirals. Mooney people are no different in that respect. Then @PT20J (Skip) comes along and ruins all the "There I was, flat on my back" stories with the regulations (reality). Yes, the M20 (and all aerodynamic model changes) had to pass the 1-turn "spin" and recovery tests. These are called spin tests because they are in that section of the regulations. At one turn, the airplane has not advanced into a developed spin yet. More on this shortly. During the stall testing, the airplane is not allowed to roll more than 15 degrees OR pitch down more than 30 degrees (or it would be noted in the POH) with normal use of the flight controls and without exceptional pilot skill (iow, you and me flying). If your airplane can't do this, something needs to be looked at/adjusted. Now let's go after the spin/spiral. Odds of spinning (and not spiraling) are low - unless you continue to input pro-spin controls. With that said, both events are extremely frightening the first many times. Most pilots when the nose drops 30 degrees will tell the story that they were pointed straight down. The stories get bigger in a spiral as the nose is much lower … still not pointed straight down. Here's how we tell the difference (and the DA video is good to watch). If airspeed is near stall speed and not increasing, the airplane is in a spin (stalled). If the airspeed is increasing, the airplane is in a spiral (not stalled). Recovery from a spin is into a spiral (you must lower the nose to reduce the angle of attack (AOA). Yes, the angle of pitch will be very nose down, and pushing at that point is counter intuitive (which is why people don't do it … and we have fatalities), but that is what is required. So, the airplane will recover very nose low (good video over the lake). Once the airplane is in a spiral (and as others have mentioned), it will pick up speed rapidly (drag of the airplane is not a huge factor … more soon). Roll wings level and pull, now. If you want to know the force you will need to pull, try to pull 3.8G in a level turn. It will surprise you how heavy that is. Now for the drag vs. "pick up speed rapidly" follow up. Think of how long it takes for the airplane to accelerate in level flight from 70 knots to Vh (maximum level speed). The propeller is producing (I'm guessing here … and it depends greatly on your model) 600 down to 200 lbs. of thrust (the faster you go, the less thrust is produced). Now, let's look at the physics of the airplane. In level flight, the weight is producing no "thrust" (force along the longitudinal axis). At an AOP (angle of pitch) of -7 degrees, the weight is producing a "thrust" of 10% of the weight of the airplane (~250 lbs.). When the nose is down 45 degrees, the weight is giving a "thrust" of 70% of the weight of the airplane (1,500 lbs.). You get the idea. The weigh component at 70 degrees nose down is >> than the thrust of your propeller … even statically (where propeller thrust is the highest). The airplane no matter how draggy will gain speed very rapidly. Bottom Line: It is not during the spin that things may wrinkle, it is in the recovery (spiral) that speed will be increasing very rapidly. Hope this helps. Civil bantering appreciated. Keep the Blue on Top. -Ron