A64Pilot Posted October 28 Report Posted October 28 (edited) 9 hours ago, 1980Mooney said: When you say "similar to a Mooney", do you mean a fuselage with "steel frame and essentially non-loadbearing aluminum skin"? The spirit of the post would be that you would not do it. Even Mooney, when they designed the pressurized M22 Mustang, ditched the steel frame and went with conventional aluminum alloy semi-monocoque structure like everyone else. https://1000aircraftphotos.com/Contributions/WestinLarry/12817.htm I think he means metal construction as opposed to composite. I prefer metal myself due to its damage tolerences and ease of repair and it’s very well known fatigue rates. However having said that I like the 4130 tube structure around me, the Meyers 200 carried that much further than Mooney, even the wings out past the gear were 4130, however this meant it was extremely labor intensive to build, Aero Commander learned that they couldn’t break even on it, it just took too many hours to build. However I believe it is the only complex airplane that has never had an airframe AD, and it’s known for its survivability, even more than Mooney. ”Spam Can” construction like Cessna, Beech, Piper etc is less labor intensive and therefore cheaper to build, composite even moreso, however it’s possibly not better as in crashworthiness. Pic of the Aero Commander line in Albany Ga probably about 1966 or so, you can see the tube steel structure and size of the tubing. Edited October 28 by A64Pilot Quote
Fly Boomer Posted October 28 Report Posted October 28 11 hours ago, wombat said: Keep going like this and the money will start to add up though. As Sen. Fulbright once opined "A billion here, a billion there -- pretty soon you're talking about real money". Quote
PeterRus Posted October 28 Report Posted October 28 49 minutes ago, A64Pilot said: Wankel’s are cool, I wish they were further developed.... Wankel’s died years ago as in I think 1973, due mostly to fuel consumption. They have other issues, too, but these are less relevant to the aviation (emission standards). Mazda made last RX-8 with a Wankel engine in 2012. Quote
Pinecone Posted October 28 Report Posted October 28 11 hours ago, wombat said: This is why you can't have fewer than two airplanes. One for XC flights. One for making holes in the sky. Also, one for landing on water. One for STOL. One for maintaining multi currency. Keep going like this and the money will start to add up though. Well, you can double up with a fun plane, that is STOL and lands on water. Maybe even multi (AirCam). My fun plane Quote
exM20K Posted October 28 Report Posted October 28 1 hour ago, PeterRus said: They have other issues, too, but these are less relevant to the aviation (emission standards). Mazda made last RX-8 with a Wankel engine in 2012. Rumors abound that Mazda will produce their concept car as the RX9, complete with a rotary, perhaps hybrid engine. Sign me up! 1 Quote
MikeOH Posted October 28 Report Posted October 28 1 hour ago, exM20K said: Rumors abound that Mazda will produce their concept car as the RX9, complete with a rotary, perhaps hybrid engine. Sign me up! While I enjoyed my RX-7 without turbocharging, it was a bit underpowered. It certainly revved like there was no tomorrow but it had very poor low end torque (which I find necessary for 'fun' street driving) Amazing engine for power to weight ratio but anyone that thinks it's a simple/low parts count engine has never rebuilt one! Also, there is no such thing as 'boring out' the epitrochoidial housing and putting in 'oversize' rotors! Trash a rotor you need a new rotor and housing $$$$. Compared with a conventional piston with five rings (two compression, plus three-piece oil control), a SINGLE rotor has 42 'ring' components to seal against the rotor housing; to be fair, the rotor is kind of like 'three pistons', so only 14 'rings' compared to 5. Quote
N201MKTurbo Posted October 28 Report Posted October 28 2 hours ago, MikeOH said: While I enjoyed my RX-7 without turbocharging, it was a bit underpowered. It certainly revved like there was no tomorrow but it had very poor low end torque (which I find necessary for 'fun' street driving) Amazing engine for power to weight ratio but anyone that thinks it's a simple/low parts count engine has never rebuilt one! Also, there is no such thing as 'boring out' the epitrochoidial housing and putting in 'oversize' rotors! Trash a rotor you need a new rotor and housing $$$$. Compared with a conventional piston with five rings (two compression, plus three-piece oil control), a SINGLE rotor has 42 'ring' components to seal against the rotor housing; to be fair, the rotor is kind of like 'three pistons', so only 14 'rings' compared to 5. I have a turbo Mazda motor in my garage on an engine stand. I intended to build a sand rail for it. It is still on the project list and probably will be for a long time. 1 Quote
A64Pilot Posted October 29 Report Posted October 29 23 hours ago, PeterRus said: They have other issues, too, but these are less relevant to the aviation (emission standards). Mazda made last RX-8 with a Wankel engine in 2012. I know, looked what happened with the RX-8 though, for automobiles I’m afraid it’s dead, as are Diesels in my opinion, yes you can make Diesels pass emissions, but it’s really, really tough and expensive. It really wouldn’t be hard to make an aircraft engine run off of car gas which is I think our biggest problem, all it would take is a modern combustion chamber, that’s why cars now can run higher compression than our aircraft engines on low octane gas, but the money to build and Certify there is no payback apparently. One advantage of a Wankel is that it can tolerate very low octane fuel without detonating, due apparently to the lack of valves. However a Wankel just isn’t nearly as thermally efficient as a reciprocating engine and there just isn’t a way around that. However the RX-8 required Premium and the engine just didn’t last often only about 60K miles, I assume but don’t know that Mazda had to run it very lean and hot to pass emissions, but they couldn’t make it pass newer emission standards and it died. Many people pre-mix fuel and oil in the RX-8 to try to make the engine last longer, Pretty sure it’s for the apex seals which has always been the achilles heel for Wankel’s, but run them hot and it kills seals. I like Wankel’s, they can be real hot rods, the turbo RX-7 made over 250 HP in stock trim with a roughly 80 cu in engine, and they are nearly turbine smooth as it simply spins and doesn’t recpriocate, but also a piston engine gets one power pulse for every 720 degrees of rotation per cylinder but a Wankel gets e power pulses per revolution so six times as many as a piston engine. ‘I think they would make a great aircraft engine, even the shape of a Wankel lends itself to aircraft. Quote
dkkim73 Posted October 29 Report Posted October 29 I used to want to put a Mazda RX engine in an RV-7/8 or EZ variant. There is a guy, Tracy something or other, who did this and wrote a book ; interesting read (helpful to speak with, too). Never got around to experimental building but I liked the power to weight. I imagine the failure modes would be less catastrophic than reciprocating. Only had an MX-5 but always like the ease of working on it and the inexpensive documentation. Quote
M20F Posted October 29 Report Posted October 29 One of my life’s desires is to see some actual numbers on a 400HP Comanche with a RayJay. Quote
aviatoreb Posted October 29 Report Posted October 29 19 minutes ago, M20F said: One of my life’s desires is to see some actual numbers on a 400HP Comanche with a RayJay. This guy actually did it 1 Quote
KSMooniac Posted October 29 Report Posted October 29 1 hour ago, A64Pilot said: ‘I think they would make a great aircraft engine, even the shape of a Wankel lends itself to aircraft. My senior design project as an aero engineering student was a 4-place RG plane with a rotary engine. Weight and physical packaging/drag reduction are huge plusses in our corner of the aviation world, but the BSFC is not great, unfortunately. I briefly dabbled with an RV-6 kit after college and was reading all I could on the conversions, but eventually came around to thinking a standard Lycoming is still optimal. I wish we had enough manufacturing scale to truly optimize a GA engine production facility to make better parts/engines and get the cost out. It seems every other industry has advanced by leaps and bounds in terms of machining quality, casting, etc. except our products in GA. 3 Quote
EricJ Posted October 29 Report Posted October 29 One of my race cars was an RX-7 that sort of fell on me after a buddy got it as payment from somebody that owed him money. It was already prepped as a race car and I think I ran it for about a year after we got it going the way we wanted it...or as much as we could, anyway. The engine was reliable, but they make very little torque. I'd race with the Porsche 944s and if I was careful I could get off the corners and ahead of them on a corner exit, but once I shifted into 4th gear they'd just disappear down the straight. There are advantages and disadvantages to the rotaries, but the disadvantages are significant enough that they've not really caught on anywhere, especially in Aviation. Moller spent a bunch of investor money "optimizing" rotaries for the Moller Sky Car (remember those?), and they were so successful that after forty years there are still no Moller Sky Cars flying. They apparently market the motors now for whoever will buy them: https://freedom-motors.com/ And the SkyCar is still evolving into new hybrid versions, with rotary motors. So rotary motors are good for vaporware because they do kinda look good on paper. Quote
PeterRus Posted October 29 Report Posted October 29 6 minutes ago, EricJ said: ...The engine was reliable, but they make very little torque. I'd race with the Porsche 944s and if I was careful I could get off the corners and ahead of them on a corner exit, but once I shifted into 4th gear ... Yes, you need to rev up a Wankel. Don't shift into 4th, stay in 3rd. (: Since majority of piston aviation engines run at high RPM -- should not be an issue, esp. considering the reduction gearbox. 1 Quote
Fly Boomer Posted October 29 Report Posted October 29 32 minutes ago, KSMooniac said: It seems every other industry has advanced by leaps and bounds in terms of machining quality, casting, etc. except our products in GA. Some late-model Toyotas are now using 0W8 oil -- pretty tight tolerances. I doubt if Toyota is the only one. I couldn't believe my eyes when I read that my car uses 0W20, but 0W8 is insane. 1 Quote
A64Pilot Posted October 29 Report Posted October 29 29 minutes ago, PeterRus said: Since majority of piston aviation engines run at high RPM -- should not be an issue, esp. considering the reduction gearbox. ? I would say the opposite most aviation piston engines are direct drive which means they have to be low RPM, reduction gearboxes bring in a whole extra layer of complexity and weight but are necessary to run higher engine RPM. I don’t know why belts haven’t been done and before anyone says that’s nuts, there are quite a few helicopters that are belt driven, and have been for decades, but I prefer direct drive. I believe a clean sheet aviation engine would have to have a least water cooled heads, that would allow car gas. Kawasaki was I think the first pent roof combustion chamber bike and they couldn’t pull off the four valve head without water cooling, so I believe that means it’s not doable, probably. I don't understand the drive for a Jet-A diesel as opposed to a spark ignition motor running car gas? Military maybe? I know they went to one fuel long ago and Companies have striven to produce products that can burn Jet-A, both Lycoming and Mercury Marine have produced spark ignition engines that can burn Jet-A for them as opposed to building Diesels, so maybe there is Government money available for Diesels? 1 Quote
PeterRus Posted October 29 Report Posted October 29 5 hours ago, A64Pilot said: ? I would say the opposite most aviation piston engines are direct drive which means they have to be low RPM... Bad wording on my part: "high RPM" -- much closer to the redline. Quote
A64Pilot Posted October 29 Report Posted October 29 Ref poor torque for a Wankel. Mazda fixed that on the four rotor motor in the 787 by having variable length intake tubes. In fact it ended up having about the flattest torque curve of any race motor. https://www.roadandtrack.com/car-culture/a36062874/mazda-787b-r26-variable-length-intake/ 1 Quote
Mooney in Oz Posted October 29 Report Posted October 29 On 10/28/2024 at 12:59 PM, wombat said: This is why you can't have fewer than two airplanes. One for XC flights. One for making holes in the sky. Also, one for landing on water. One for STOL. One for maintaining multi currency. Keep going like this and the money will start to add up though. Owning just one starts to add up 1 1 Quote
A64Pilot Posted October 30 Report Posted October 30 (edited) 12 hours ago, Mooney in Oz said: Owning just one starts to add up It does, but if one owns their own hangar and has room for two, a simple airplane really isn’t that expensive to own. I don’t remember what I paid for my 140 20 years or so ago, I think about 12K or about the same as an average used car back then, but it has cost nearly nothing to maintain as it’s just a simple carbureted lawnmower engine that’s as easy as it gets to work on, runs on car gas etc. I should overhaul the cylinders as I have high oil temp that’s from blow by I’m pretty sure, but it’s been that way for all of those 20 years, I’ll get around to it eventually It’s not a traveling machine, but for those that have those big expensive fast Mooney’s you’re missing out on some really good local fly ins to grass strips etc. or just flying around one late Summer afternoon with the window open and your arm on the window sill. It’s the complete opposite to those that want fancy glass to entertain themselves with, it’s simple stick and rudder flying, great for spins etc. From what I have heard my 140 is worth now it’s pretty much doubled in value meaning that I won’t really make money if I sold it but that I would have owned and enjoyed it for the last 20 years essentially for free, plus it’s not in danger of being legislated into non existence as it burns car gas and believe it or not but every part is readily available, even large airframe parts inexpensively, no little $3,0000 springs. There is a lot to be said for having a simple inexpensive airplane. As I continue to grow older one day of course I’ll sell the Mooney, but I plan on keeping the 140 until I can’t get in and out of it Edited October 30 by A64Pilot 3 Quote
A64Pilot Posted October 30 Report Posted October 30 (edited) 15 hours ago, PeterRus said: Bad wording on my part: "high RPM" -- much closer to the redline. The redline on most aircraft engines usually isn’t an engine redline, but a prop redline, and even then it’s almost never a structural limit, it’s usually a noise limit. Usually, I’m sure there are exceptions, there always are. Now it IS a limit and therefore we have to obey it of course. Very often the Redline is a way for the engine manufacturer to limit the engine HP, for example the 235 IO-540 redline is 2400 because that’s 235 HP while the lower compression carbureted O-540 is I think 2600 because that’s where 235 HP occurs. Then in most cases it’s a continuous limit too, whereas in say automobile engines for example it’s rarely a continuous limit. The IO-520 in the C-210 I had was allowed to turn 2850 and make 300 HP, for 5 min, it was an exception to the rule, continuous limit was 2700. I’m pretty sure it couldn’t be Certified that way now because it was noisy at 2850. I’m also pretty sure the 5 min limit was due to heat build up, not a structural engine limit. Increase HP and of course you do that by increasing heat, if you exceed the cooling systems capacity then of course you can’t do that for long. But anyway we shouldn’t think of our aircraft engines redline in the same we we do our cars or motorcycles, those are usually actual engine structural and or heat limits and you can’t hold redline for long before something bad happens, where the average airplane can hold redline continuously. Edited October 30 by A64Pilot Quote
Ibra Posted October 30 Report Posted October 30 (edited) That would be TBM? it's sort of mariage between M20 and TB20 before putting PT6 in front M22 did not have the PT6, it would have been a sort of sucess story if it had one... I flew T34C while ago, it's basically a Bonanza with turbine in front yet way too slow: the Bonnie airframe could not keep up with 1mph for every 1hp (the TBM actually managed to keep with Mooney tradition: it has lot of speed for every horse power) Go for TBM (or PC12) as they look like "turbine Mooney" (if you are into experimentals, go for turbine Lancair) Edited October 30 by Ibra 2 Quote
LANCECASPER Posted October 30 Report Posted October 30 29 minutes ago, Ibra said: That would be TBM? it's sort of mariage between M20 and TB20 before putting PT6 in front M22 did not have the PT6, it would have been a sort of sucess story if it had one... I flew T34C while ago, it's basically a Bonanza with turbine in front yet way too slow: the Bonnie airframe could not keep up with 1mph for every 1hp (the TBM actually managed to keep with Mooney tradition: it has lot of speed for every horse power) Go for TBM (or PC12) as they look like "turbine Mooney" (if you are into experimentals, go for turbine Lancair) The Mooney 301 would have been the perfect candidate for a turbine. https://www.planeandpilotmag.com/aircraft/brands/mooney/301/mooney-301/ https://mooneyspace.com/search/?q="Mooney 301"&quick=1&updated_after=any&sortby=relevancy 1 Quote
Pinecone Posted October 30 Report Posted October 30 1 hour ago, A64Pilot said: The redline on most aircraft engines usually isn’t an engine redline, but a prop redline, and even then it’s almost never a structural limit, it’s usually a noise limit. Usually, I’m sure there are exceptions, there always are. I don't know about these days, but a while ago, the serious aerobatic guys were running IO-360s to 3400 RPM for the extra power. Along with high compression pistons and helicopter cams. Engine life was NOT very long. Quote
Yetti Posted October 30 Report Posted October 30 Someone said it once already, you are not going to be a store enough Jet A in a Mooney to get you much past take off. Possibly with a smaller turbine. Quote
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