Gary0747

I agree. I have heard that max speed drove Mooney marketing and this likely overruled sound engineering judgement with the end result being the worlds fastest single engine piston airplane but overlooking the fact that this airplane limited by the landing gear design and costing close to a million dollars would often have 500 pounds or less pay load with full fuel. Little wonder why Mooney went bankrupt again! Roy Lopresti was the smartest engineer to work for Mooney and he apparently saw a way around this problem but may not have been listened to. This design he was working on was after he left the company.

Good question. Think about the possibilities here. The empty weight of a mid body 252 is 1800 pounds which is 450 pounds less than an ovation one. The ovation is supposedly weight limited to about 3360 pounds for taking off because the landing gear design is maxed out. If the take off weight of the 252 is limited by its raw horsepower at take off and the engine were replaced with a NA engine yielding about the same gross weight as the 252 but having 260 horsepower at take off compared to 280 horsepower of the much heavier ovation one why would it not be able to get much closer to the 3360 take off weight of the ovation one? The potential here is to have a NA Mooney with close to 1500 pound take off weight! I wish somebody would show me where my thinking is wrong

Was the main reason to lengthen the body to balance the heavier engines? The ovation is about 20 inches longer than a J but the length added was about 10 inches in the baggage compartment while maintaining the 120 pound limit to baggage there. I think most of the other 10 inches is in the longer engine? This lengthening and heavier engines allowed Mooney to continue to claim the speed title even though the extra length no doubt added some to the aerodynamic drag, and did some things with the aerodynamics that caused the factory to say “no slips should be used on final”. The added weight put the Mooney rubber donut landing gear at the upper design weight limit and dramatically shortened the life of the donuts. So Lopresti may have some reasoning behind his lighter balanced mid body design. Many have said that the mid body 252 is the best most efficient Mooney ever built. If this is true then a normally aspirated version of that could have been a good seller. The key here may well have been finding a NA engine close to 100 pounds lighter than the current large 6 cylinder engines.

Here is the actual article from 27 years ago. It sounds like a special Lycoming 540 that may not be available today? Roy did live another 8 years. And the cowl referenced Or variant of it is available today. I wonder what Roy thought of the long body Mooney’s And reasons for lengething them, since the mid body’s were his engineering babies.

I know this has been over debated but I wanted to throw this one out there. I was reading in an old MAPA Log (Nov. 1993) that Roy Lopresti as one of his last projects was working on a mid body variant that I think would have been almost perfect for me. He was going to take the 231 and remove the Continental TSIO 360 and replace it with a special variant of the Lycoming IO 540. It was a parallel valve 260 hp engine that weighed 10 pounds less than the original Continental. For us not interested in flying in the flight levels and not liking the massive Continental 520 series and all the issues with reliability, cooling, and having to counter balance the extra weights of the engines in the Rocket Engineering conversions this might have been the perfect Mid body fit. The Lycoming reliability and likely smaller size of this 540 would have been a major attraction to some that did not prefer the longer body Mooney’s. I assume this smaller Lycoming 540 variant might have been related to the smaller Lycoming IO360 Variant that is rated at 180 hp? I never heard what might have happened to Lopresti project. I think he died not long after this.

I wonder if there are any avionics shops who will work on the Sandel 3308? It does seem a shame that the LCD screens can’t be replaced for less than 2 AMUs Any idea what the guy who wanted your two units with LCD problems intended to do with them?

Your original unit may have just been fine. There have been people trying to save a few dollars on the 12volt halogen projector bulbs. They can be bought for less than 5 dollars with the same wattage and specs as the bulb Sandel sells you for $150. The problem is the height of the bulb filament above the base varies and that can affect the display brightness and brightness location since the light is reflected off a mirror and the dimensions and angles are critical. Also not having the pot hooked up properly can lead you to believe you have a problem. Check some of the old discussions on the 3308 o the Beech web site for some good background.

As far as I know, There is no way of knowing what you are seeing on your screen is TISA or TISB?

I would think things like charging amp load over time and quality of the carbon in the brush will impact the overall life of the brush. The brushes are cheap but hard to change especially the top one on my F. It requires either dropping the generator or removing a baffle.

I was looking for experience data on how long the brushes last on our old Delco 50 amp generators? Do they typically last longer or shorter than alternator brushes?

Are the mechanical stops normally set so that the max rpm is closer to 2700, not 2850?

http://www.kathrynsreport.com/2020/05/mooney-m20j-201-n201hh-accident.html

My thoughts with having the higher ignition spark on the same side of all the cylinders either bottom or top have to do with uniformity of the ignition generated flame fronts between all cylinders. This might make for a smoother running engine. Just wondering if anyone has tried it both ways, all one side versus staggered?

I understand some have installed their Shurefly so that it feeds just the bottom spark plugs. I think most have left their spark plug harness as original with some wires from the Shurefly going to the top plugs and some going to the bottom plugs. Does anybody have any data comparing these two options?

Spring type washers serve a valuable purpose and in some applications are preferred over locking washers with teeth that grab the nut. Especially in applications where you have large temperature cycles that will change the length of the bolt and reduce the preload torque. The Belleville cup spring washer is used extensively in the Chemical Process Industry on equipment such as heat exchangers and reactors. If specified properly it will maintain preload through a variety of temperature and pressure situations. Our Magneto studs see some of these temperature changes but whether it is enough to cause a problem is debatable. It does seem like we have seen a lot of magnetos coming lose and we tend to blame them all on maintenance error. Perhaps loss of preload could be a contributing factor in some? https://en.wikipedia.org/wiki/Belleville_washer

Those Mooney performance charts all assume you have a working governor. It seems to me that it all depends on where the mechanical stops are set for that prop. In an extreme situation if the pitch of the blades were allowed to go completely flat one would just have a prop spinning generating little or no thrust. The mechanical stops are supposed to prevent this but I have never seen any info on a power vs rpm with the prop testing on the stops. I think Carusoam above eluded to this situation when he had his governor fail in his C model.

How much power will a prop that has failed to flat pitch generate without exceeding 2700 rpm?

I have never really understood why Mooney considered the change from the IO360A1A to the IO-360-A3B6D when they came out with the 201 as an improvement? We all know the saga of incidents with the single drive mag. But also the IO-360-A3B6D has counter weights on the crank. The A1A has no counter weights and have ridden behind both engines I have never been able to tell if the counter weights made the IO-360-A3B6D smoother? I see the old ADs on the counter weights plus the seem like one more piece to be thrown off in case of an over speed incident. I assume the overhaul costs are more but never really checked that out. Am I wrong on this or missing something? Maybe I am biased owing an F.

Why did the engine mfg not specify reusable self locking nuts?

I see no signs of oil loss in the video..sometimes a governor can just fail with out an oil loss. Over speed can toss a rod.

How would a person keep a plane in the air with out over speed damage to the engine if the governor failed to the flattest pitch position?

I see Lycoming specifies a special lock washer for magneto hold down bolts. Is it really a special part or just a pricey relabel of a standard lock washer? STD-475 LYCOMING WASHER, .3125 LOCK INT. TEETH

With the Shurefly as the left mag, why is it not possible to hand prop to start? It has to be a very dead battery not to have the 0.5 amp current necessary to run the Shurefly.

I am currently flying out of KDVT in Phoenix which is very busy with flight school traffic. My last flight departed runway 25 with a turn to the North West under the Class B shelf. Traffic in the area was busy as it normally is but I was somewhat comfortable with knowing that most all the traffic could be visually spotted with the assistance of my ADSB in. I was passing about 1500 feet below and between two slower aircraft headed in my general direction with a good visual on both. When I was about a mile from the aircraft on my left he made an abrupt 270 degree descending turn directly towards me causing a rapid closure rate. Fortunately we missed but it was way to close of a call for my comfort. I am not sure he ever saw me given he was descending and I was below him. I did get his N number from my ADSB in data and looked it up to see it belonged to one of the two big flight schools here at KDVT. I called the school and talked to the head flight instructor. I was curious why this student did not do a clearing turn and why he did not see me on his ADSB in? I was surprised at his response that “not all our aircraft have ADSB in”. I said as inexpensive as these systems are it would make sense for training aircraft doing maneuvers under the class B shelf to have these. It was only a couple of years ago that they had two training aircraft collide just north of KDVT. My phone call may or may not have had any beneficial effect. Any thoughts or advice?

I have read all the engine mount shimming advice here and on Don Maxwell’s site. They all say to center the prop spinner in the cowling, but my question is shouldn’t the engine be canted to the right slightly due to the P-Factor of the rotating prop?