exM20K Posted July 2, 2021 Report Posted July 2, 2021 @aviatorebthke a look at the window and door dimensions in a P210 vs a non-pressurized 210. Airtight bladder is a interesting and new-to-me solution, but it would be very difficult for the existing windows and door latch to withstand any pressure differential. Anything can be beefed up, of course, but there goes your useful load. -dan 1 Quote
aviatoreb Posted July 2, 2021 Report Posted July 2, 2021 1 hour ago, exM20K said: @aviatorebthke a look at the window and door dimensions in a P210 vs a non-pressurized 210. Airtight bladder is a interesting and new-to-me solution, but it would be very difficult for the existing windows and door latch to withstand any pressure differential. Anything can be beefed up, of course, but there goes your useful load. -dan Sure- I bet there would be issues - but maybe maybe - it could be done? And lighter /stronger materials than the way it was done in the p210 - we have much better materials then they did when the p210 was designed. Quote
EricJ Posted July 2, 2021 Report Posted July 2, 2021 (edited) 32 minutes ago, aviatoreb said: Sure- I bet there would be issues - but maybe maybe - it could be done? And lighter /stronger materials than the way it was done in the p210 - we have much better materials then they did when the p210 was designed. Your bladder has to deal with nominally an 8psi pressure differential (roughly 8-10psi in typical aircraft pressurization systems, but for small airplanes we can say 8-8.5psi.). So we can make some rough calculations of the amount of force on various important components. Using a page from a random M20J POH, we can use some rough published dimensions for the door and hatch, and take a guess at a typical window. From here:https://www.manualslib.com/manual/1339371/Mooney-M20j.html?page=15 A rough door dimension is 29"x35" = 1015 sq in. A rough hatch dimension is 20.5" x 17" = 348.5 sq in. A rough random side window might be about 16" x 24" (totally guessing on this) = 384 sq in. So the force on the door is roughly 1015 sq in x 8.5 psi = 8625 lbs. On the hatch: 348.5 sq in x 8.5 psi = 2962.25 lbs. On the example window: 384 sq in x 8.5 psi = 3264 lbs. Those are only small fractional portions of the total area that has to be contained by the "bladder", without exerting force on the exterior structure that would cause it to fail. It also has to be transparent and not impede view out the windscreen and windows (since they can't take that amount of force), and also have seams at the door and hatch that will prevent leakage as well as some means of fresh air ventilation and a source of pressurization. There are also a lot of safety things to consider with pressurized systems, like how to prevent hatches and doors from opening under pressure, and ways to dump pressurization in an emergency, etc., etc. And nothing in AC 43.13 will apply any more regarding repairs, since all of that only applies to non-pressurized aircraft. i.e., repair methods are gonna all have to be figured out specifically for that system. If the bladder isn't strong enough to contain those forces, it'll transmit them to the existing structure/windows/doors/hatches/etc., and if they're not engineered to take it they'll probably fail within a few cycles if not immediately. Anyway, pressurization is a whole different ballgame for the entire airframe, and they're treated very differently under the regs. This is why I think it'd be interesting to start with an M22 Mustang airframe, since it is already a certificated pressurized aircraft. If I was gonna hang a hairdryer on a Mooney, to me that'd be the obvious one to do it to. It would still make zero sense and I don't think you could expect to sell many even if you had new production airframes to work with, but it would be fun to see if somebody else were paying for it. Edited July 2, 2021 by EricJ 1 Quote
FoxMike Posted July 2, 2021 Report Posted July 2, 2021 To save money on redesign of the airframe you could wear a spacesuit. 2 Quote
aviatoreb Posted July 2, 2021 Report Posted July 2, 2021 Just now, FoxMike said: To save money on redesign of the airframe you could wear a spacesuit. Yeah - I was think that but what about headroom? Quote
carusoam Posted July 2, 2021 Report Posted July 2, 2021 Sounds like… A dual O2 system will work pretty well until we get the pressurization figured out… Why dual… Expect that flying at 25k’ will be a common altitude to get to… climb speed is available, cruise speed will be maxed out…. (?) Time of useful consciousness is relatively low at that altitude… A spare O2 system continuously operating to fill in for what ever part stop working… will be appreciated. Do we have a continuous O2 monitor/alarm wearable yet? Continuous 310hp has proven to be plenty of power for LB Mooneys… More would be better, if cost of operations and weight penalties are kept in the ball park… The JetProp makes a great comparison… as a couple of MSers went from Long Body to a JetProp on their step up… The other really close competition… for turbine and four seats… is @Yooper Rocketman’s Lancair IVPT… it was close enough, he went from a Mooney Rocket to the composite, pressurized four seater…. When it comes to having too much power…. We all encounter this when things get bumpy…. We start calculating our current gross weight and adjust to maneuvering speed accordingly… Mooney PICs have been pretty good at not exceeding speeds where parts of planes get torn from their mounts or get bent at funky angles… I’m looking forward to the day where I’m not always wondering if my cam, it’s followers, or it’s fasteners are all holding together as expected… Rational fear is a great sales tool for considering a turbine… Getting away from 100LL this century might be a good idea too… Putting the prop in beta mode… might put icing on the cake… 2k’ long runways are typical Mooney home dromes… When balanced out… TBOs and OH costs for the various power plants are pretty close together… IO550 vs small turbine… Rocket Engineering has done a great job of making a business out of putting newer technology on the front of Mooneys… Rocket, Missile, O3’s 310hp IO550… Screamin’ Eagle and Standing Ovation… They also are the parent of the JetProp… Around 2007 Mooney announced their partnership with RR to hang a turbine on the front of a LB… Use caution… putting a turbine on the front of a Mooney was a strong signal the economic top was near… Hmmm…. Fun reading… for turbines and pressurization or not… https://www.avbuyer.com/articles/refurbishment/piston-to-jetprop-conversions-20432 I never really think about this stuff at all… Best regards, -a- 2 Quote
Browncbr1 Posted July 2, 2021 Report Posted July 2, 2021 I wish someone would put this kind of money and effort into a turbo diesel conversion. 1 Quote
Raptor05121 Posted July 2, 2021 Report Posted July 2, 2021 13 hours ago, exM20K said: with another 200# of useful load, I think the Acclaim is about the perfect HPSE plane. Range, speed, climb rate, operating economics are all excellent. -Dan Your wish just came true. The Pipistrel Panthera is basically a better Ovation with a BRS. It has a 260hp IO-540 that does 200KTAS @ 15gph at 75% power or dial back to 65% and it'll do 185KTAS @ 10.8gph. All with a 1,100lb useful load. Max gross 2900lbs and they are toting it will be certified to 3,000lbs which possibly means 1,200lbs useful? Plus, it can burn MoGas And it has a parachute. I just read the AOPA flight test about it in the FBO last night. The name "Mooney" was used several times. Very close competitor except it has 21st century clean sheet design basically capitalizing on Mooney's 60-year design. Faster, less fuel burn, better (personal opinion) engine than the Continental, more efficient, more useful load. And a freaking BRS system. All for the same price as an Acclaim. The actual numbers in the article were impressive. Quite literally what I've been daydreaming about if Mooney made a new carbon-fiber design. Little different styling, but if I had three-quarter mil in my pocket for HPSE piston, I'd quickly place an order for one of these over a new Ovation. 2 Quote
pinkiedog64 Posted July 2, 2021 Report Posted July 2, 2021 11 hours ago, EricJ said: Your bladder has to deal with nominally an 8psi pressure differential (roughly 8-10psi in typical aircraft pressurization systems, but for small airplanes we can say 8-8.5psi.). So we can make some rough calculations of the amount of force on various important components. Using a page from a random M20J POH, we can use some rough published dimensions for the door and hatch, and take a guess at a typical window. From here:https://www.manualslib.com/manual/1339371/Mooney-M20j.html?page=15 A rough door dimension is 29"x35" = 1015 sq in. A rough hatch dimension is 20.5" x 17" = 348.5 sq in. A rough random side window might be about 16" x 24" (totally guessing on this) = 384 sq in. So the force on the door is roughly 1015 sq in x 8.5 psi = 8625 lbs. On the hatch: 348.5 sq in x 8.5 psi = 2962.25 lbs. On the example window: 384 sq in x 8.5 psi = 3264 lbs. Those are only small fractional portions of the total area that has to be contained by the "bladder", without exerting force on the exterior structure that would cause it to fail. It also has to be transparent and not impede view out the windscreen and windows (since they can't take that amount of force), and also have seams at the door and hatch that will prevent leakage as well as some means of fresh air ventilation and a source of pressurization. There are also a lot of safety things to consider with pressurized systems, like how to prevent hatches and doors from opening under pressure, and ways to dump pressurization in an emergency, etc., etc. And nothing in AC 43.13 will apply any more regarding repairs, since all of that only applies to non-pressurized aircraft. i.e., repair methods are gonna all have to be figured out specifically for that system. If the bladder isn't strong enough to contain those forces, it'll transmit them to the existing structure/windows/doors/hatches/etc., and if they're not engineered to take it they'll probably fail within a few cycles if not immediately. Anyway, pressurization is a whole different ballgame for the entire airframe, and they're treated very differently under the regs. This is why I think it'd be interesting to start with an M22 Mustang airframe, since it is already a certificated pressurized aircraft. If I was gonna hang a hairdryer on a Mooney, to me that'd be the obvious one to do it to. It would still make zero sense and I don't think you could expect to sell many even if you had new production airframes to work with, but it would be fun to see if somebody else were paying for it. In addition to these great concept-stopping points, how do you assemble this fuselage and keep things accessible for maintenance? If you retain the tubular structure and the non-structural aluminum fuselage skins, and put inside the tubular structure a carbon pressure vessel, you have to be able to install it somehow. As mentioned above, it can't just be an airtight membrane; it has to react pressure loads (which are tremendous) by means of hoop stress, otherwise it pushes out on the tubular structure which it isn't designed for. So the carbon pressure vessel has to be a rigid structure. How do you get this rigid structure (that is just smaller than the tubular structure) inside of the tubular structure? You can't. You also can't weld the tubular structure around the carbon pressure vessel. And spacesuits cost a gazillion bucks. 1 Quote
aviatoreb Posted July 2, 2021 Report Posted July 2, 2021 11 hours ago, EricJ said: Your bladder has to deal with nominally an 8psi pressure differential (roughly 8-10psi in typical aircraft pressurization systems, but for small airplanes we can say 8-8.5psi.). So we can make some rough calculations of the amount of force on various important components. Using a page from a random M20J POH, we can use some rough published dimensions for the door and hatch, and take a guess at a typical window. From here:https://www.manualslib.com/manual/1339371/Mooney-M20j.html?page=15 A rough door dimension is 29"x35" = 1015 sq in. A rough hatch dimension is 20.5" x 17" = 348.5 sq in. A rough random side window might be about 16" x 24" (totally guessing on this) = 384 sq in. So the force on the door is roughly 1015 sq in x 8.5 psi = 8625 lbs. On the hatch: 348.5 sq in x 8.5 psi = 2962.25 lbs. On the example window: 384 sq in x 8.5 psi = 3264 lbs. Those are only small fractional portions of the total area that has to be contained by the "bladder", without exerting force on the exterior structure that would cause it to fail. It also has to be transparent and not impede view out the windscreen and windows (since they can't take that amount of force), and also have seams at the door and hatch that will prevent leakage as well as some means of fresh air ventilation and a source of pressurization. There are also a lot of safety things to consider with pressurized systems, like how to prevent hatches and doors from opening under pressure, and ways to dump pressurization in an emergency, etc., etc. And nothing in AC 43.13 will apply any more regarding repairs, since all of that only applies to non-pressurized aircraft. i.e., repair methods are gonna all have to be figured out specifically for that system. If the bladder isn't strong enough to contain those forces, it'll transmit them to the existing structure/windows/doors/hatches/etc., and if they're not engineered to take it they'll probably fail within a few cycles if not immediately. Anyway, pressurization is a whole different ballgame for the entire airframe, and they're treated very differently under the regs. This is why I think it'd be interesting to start with an M22 Mustang airframe, since it is already a certificated pressurized aircraft. If I was gonna hang a hairdryer on a Mooney, to me that'd be the obvious one to do it to. It would still make zero sense and I don't think you could expect to sell many even if you had new production airframes to work with, but it would be fun to see if somebody else were paying for it. Is 8psi a transport jet pressure? (Although I my rough inexpert memory suggests 10 or 12psi? for good cabin pressure at FL43?) A Cessna P210 only gives 3.35psi. I feel even 3.0psi would be useful. I found out the operational outcome. 3.35psi gives a 10k cabin pressure at FL20. Anyway if that's all we need then the pressurization structural loads are not as dramatic. Quote
aviatoreb Posted July 2, 2021 Report Posted July 2, 2021 37 minutes ago, pinkiedog64 said: In addition to these great concept-stopping points, how do you assemble this fuselage and keep things accessible for maintenance? If you retain the tubular structure and the non-structural aluminum fuselage skins, and put inside the tubular structure a carbon pressure vessel, you have to be able to install it somehow. As mentioned above, it can't just be an airtight membrane; it has to react pressure loads (which are tremendous) by means of hoop stress, otherwise it pushes out on the tubular structure which it isn't designed for. So the carbon pressure vessel has to be a rigid structure. How do you get this rigid structure (that is just smaller than the tubular structure) inside of the tubular structure? You can't. You also can't weld the tubular structure around the carbon pressure vessel. And spacesuits cost a gazillion bucks. Right - for the price of a space suit - I think it would be cheaper to buy a Honda jet. The ultimate small jet. But wouldn't we look cool walking through the FBO out on to the tarmac and then to our airplane carrying our air conditioner suitcases - all in slow motion of course because astronauts always walk in slow motion to the space ship - then we do the preflight etc in the space suit - lock on the helmet....and off we go! I wonder of space suit shoes would fit in the pedal wells? Quote
EricJ Posted July 2, 2021 Report Posted July 2, 2021 8 minutes ago, aviatoreb said: Is 8psi a transport jet pressure? (Although I my rough inexpert memory suggests 10 or 12psi? for good cabin pressure at FL43?) A Cessna P210 only gives 3.35psi. I feel even 3.0psi would be useful. I found out the operational outcome. 3.35psi gives a 10k cabin pressure at FL20. Anyway if that's all we need then the pressurization structural loads are not as dramatic. Roughly: Most outflow valves (the regulator) run nominally around 8psi, but, yes, you can do with less if you're okay with either a higher cabin altitude or a lower max pressure altitude that can maintain that cabin altitude. And note that the chart is pressure altitude, MSL may be lower. Even assuming 3-4psi the forces are still very large. Cutting the previous numbers in half still leaves large force numbers. Quote
aviatoreb Posted July 2, 2021 Report Posted July 2, 2021 10 minutes ago, EricJ said: Roughly: Most outflow valves (the regulator) run nominally around 8psi, but, yes, you can do with less if you're okay with either a higher cabin altitude or a lower max pressure altitude that can maintain that cabin altitude. And note that the chart is pressure altitude, MSL may be lower. Even assuming 3-4psi the forces are still very large. Cutting the previous numbers in half still leaves large force numbers. Thanks for that chart - I have never been anywhere near a jet so I am otherwise unfamiliar with the actual chart you just showed. I agree- its extra ordinarily unlikely but I was spitballing an idea. Halving or even 1/3rd-ing the numbers you gave, its still quite a load. Quote
aviatoreb Posted July 2, 2021 Report Posted July 2, 2021 I think Mooney has a distinctive appearance - and a shape that is clearly excellent evidenced by the amazing efficiency and speed of the acclaim. Some here have said clean sheet - and I agree - I always liked what this company did to the Piper Comanche concept - the Raven - they built an experimental kit out of carbon fiber that has all the shapes and appearance of the piper Comanche, but its a bit faster because its smoother. And of course all the details of its construction are different. Imagine if Mooney did this with their M20. It would be faster, more modern, and they could pressurize it and add a chute. It would take money to certify it of course. But maybe they could give up on certified and just make an experimental kit? http://all-aero.com/index.php/54-planes-p-q-e-r-s/13239-ravin-aircraft-ravin-500 Quote
EricJ Posted July 2, 2021 Report Posted July 2, 2021 16 hours ago, ChrisH said: A little bit on the small side, but https://www.turbotech-aero.com/solutions/#turbogenerator would be an interesting choice in powerplant if the main concern was fuel availability & reliability (and not speed). Apparently this is already a bigger thing than I realized. Honeywell appears to be looking in this direction as well (which makes sense, since it is basically an APU):https://aerospace.honeywell.com/us/en/learn/about-us/blogs/hybrid-electric-flight Quote
A64Pilot Posted July 4, 2021 Report Posted July 4, 2021 On 7/2/2021 at 11:48 AM, EricJ said: Apparently this is already a bigger thing than I realized. Honeywell appears to be looking in this direction as well (which makes sense, since it is basically an APU):https://aerospace.honeywell.com/us/en/learn/about-us/blogs/hybrid-electric-flight Many cruising Sailboaters think electric propulsion is their future, but it’s not, direct drive off of a Diesel is much cheaper, lighter and more efficient. However you simply cannot convince them, they are certain that a Prius type of Catamaran is feasible, and several have been built, none have been successful, but “Green” sells, even if it’s not Green, the upcoming Hummer EV for example. Hybrid electric drives make sense if the mechanical drive train is difficult, a Train for example, there have been direct drive Locomotives, but boy can you imaging the transmission required. ‘So for these interesting flying car concepts I keep seeing with multiple propulsors, maybe then a Hybrid drive makes sense and add a battery to give you a extra short time boost like Formula one is doing and I think Porsche has a lot of experience in. Quote
A64Pilot Posted July 4, 2021 Report Posted July 4, 2021 (edited) 3 PSI is an enormous amount of force, the Goodyear blimps internal pressure to keep it rigid is .07 PSI. 3 PSI would most likely blow your fuel tanks for example. ‘My inflatable dinghy was inflated to 3 PSI, and when you sat on the tubes at 3 PSI it felt like sitting on a log Think about it, it’s 3 pounds for every square inch, so even a 10” x 10” square has 300 lbs of force on it. ‘Unless I messed up the math, I’m bad at that, so if I did I apologize. Maintaining a pressurized aircraft is real $$$, if for example you want to install a GPS antenna, you have to pierce the pressure vessel to do so, that’s a major modification and may involve a structural DER to analyze and design the installation. I’d hope the manufacturer has designed in places for antennas and an approved method, but as I have never maintained one I don’t know. It’s just my understanding that simple things get complicated on a pressurized aircraft, and complicated means $$$. Like windshield replacements for example. Edited July 4, 2021 by A64Pilot Quote
Jerry 5TJ Posted July 5, 2021 Report Posted July 5, 2021 PA46 cabins are pressurized to 5.3-5.5 psi. That gives about a 9,500’ cabin at FL280. Cessna P210 differential is 3.3 psi for 12,500’ cabin at FL250. The hypothetical P-Mooney should probably aim for at least 5 psi and 6.5 would be a nice target. Heck, dream big. 2 1 Quote
A64Pilot Posted July 5, 2021 Report Posted July 5, 2021 Based on older aircraft designs, and composites may change this, but smaller aircraft when pressurized, gain so much weight and useful load and performance suffers so much from the excess weight that they aren’t usually very successful. A Mooney may be too small, then the usual reaction is to chase the competition, so I’d expect two doors and a Ballistic chute to be desired by the sales guys, but add in the extra weigh of retractable, steerable gear and your probably back to being too heavy. ‘Often as aircraft designs mature, they go through cycles of losing performance, getting heavy, adding bigger engines fo recover lost performance, getting heavy again, gross weight increases fo recover useful load. ‘But sometimes if you compare the old lightweight model to the newer heavier model, there isn’t much difference in load carrying ability and even performance. ‘I know this is all a thought exercise, but it may be that the current airframe and design has reached a point that there just isn’t a whole lot left in it, and it may be that a clean sheet design is what it would take, and I’d assume likely composites. The P-210 is I think the smallest pressurized single, and it’s not all that small, it’s pretty big for a single piston, possibly too big and heavy for a piston. ‘But then again, it’s an old metal design that has evolved over they years into a much heavier airplane, it’s I’d guess pushing that airframes capability pretty hard, of course one hasn’t been built for a long time either. So that leaves the Piper as the only single engine pressurized piston? It’s a new design, not one that evolved? Quote
cujet Posted July 5, 2021 Report Posted July 5, 2021 (edited) I thought I'd chime in as a PC-12NG operator and former RR250 powered helicopter operator. (MD520N and MD600N) . We also operate a G550, G600, EC-135 heli, Extra 300L+NG (yes, the new one) and a Stemme S-10 motorglider. Turbine power is absolutely wonderful, smooth and reliable. The increased fuel burn is often partially offset by the lower price, that part is lost on no one. A post above mentioned a derated engine and it's benefits. This is the right way. A properly engineered turbine configuration will give a superb climb rate, at a high ground speed. As getting into thin air is what makes turbines viable. The G600, for example will climb at M0.86-0.87 and still make 2000-3500 FPM (or even 4000FPM if light), then settle into a cruise speed of M0.90-0.91 (or about 600+Kts TAS) So, in climb the nose is not high, the ground is moving by very quickly, and much time is saved. The bottom line is this, thin air makes a turbine worthwhile. The G600 engines burn a touch more fuel than the G550 engines (about the same thrust) but the speed difference is enough to fully offset the fuel burn. Miles per gallon is the same as the G550. The turbine advantage in helicopters is simply the weight savings. Our twin 700HP engines weigh about 250 pounds each. We can safely fly up to 2 hours, or about 275 miles in real world terms, on 160 gallons. Imagine the weight of 2 piston 700HP engines!! We'd have no useful load, and remember, we don't often top off, as our missions are 45 mins max. Here is a great page showing BSFC numbers for various engines. (and efficiency numbers) Notice the piston vs turbine efficiency. And always remember, aircraft operate by weight, not by gallons. https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption#:~:text=Brake-specific fuel consumption (BSFC,divided by the power produced. Edited July 5, 2021 by cujet For Clarity 2 Quote
cujet Posted July 5, 2021 Report Posted July 5, 2021 Also of note, small-ish turbine engines with exhaust heat "recuperation" are (for this discussion) about as efficient as gasoline engines when at rated power. The link is for a RR250 that has the heat exchangers right in the ducts. They claim 50 pounds of weight. Exhaust heat is used to heat the compressed air prior to the combustion chamber, via a heat exchanger, thereby lowering the amount of fuel necessary to achieve a specific turbine inlet temperature. https://www.ainonline.com/aviation-news/2009-02-21/hot-idea-rr-250-could-cut-fuel-burn-40 https://frontlineaerospace.com/technologies/microfire-recuperator/ 3 Quote
carusoam Posted July 6, 2021 Report Posted July 6, 2021 Great insight cuj! Thanks for sharing the details… Best regards, -a- Quote
Jerry 5TJ Posted July 6, 2021 Report Posted July 6, 2021 On 7/5/2021 at 9:08 AM, A64Pilot said: So that leaves the Piper as the only single engine pressurized piston? It’s a new design, not one that evolved? Yes, it was a clean-sheet design (starting around 1982) for a pressurized 6-seat single cruising 200 knots at FL200. Quote
aviatoreb Posted July 6, 2021 Report Posted July 6, 2021 2 minutes ago, 1980Mooney said: This topic sounds like a thought exercise on how to take a plane that is currently unprofitable to manufacture and unaffordable to purchase new by most and to make it more unaffordable to purchase, operate and maintain....and not pressurized and for not a lot of gain in speed. That is some pretty pricy "starting noise". Maybe it would be less expensive to add a high fidelity stereo speaker set one under each wing and one under the cowl that blasts high pitch turbine engine starting noises if you sit in the cockpit and press a big red button? 1 1 Quote
smwash02 Posted July 6, 2021 Report Posted July 6, 2021 15 minutes ago, aviatoreb said: Maybe it would be less expensive to add a high fidelity stereo speaker set one under each wing and one under the cowl that blasts high pitch turbine engine starting noises if you sit in the cockpit and press a big red button? Like what Ford did with the Mustang? 1 Quote
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