Vmc Roll

I'm multi rated but would not be comfortable flying a piston twin without a whole bunch of extra training because all my twin experience is in jets where Vmc LOC is just not a thing.
 
RudyP said:
I'm multi rated but would not be comfortable flying a piston twin without a whole bunch of extra training because all my twin experience is in jets where Vmc LOC is just not a thing.
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Pitch targets still work to prevent LOC in piston twins. :cool:
 
Rein Hart said:
I wonder if there's demand for a new twin engine single prop experimental design for general aviation? 2 engines feeding power into a transmission for 1 prop. Some dual engine helicopters achieve this right? Perhaps a smaller version of Soloy Dual Pac? https://www.soloy.com/dual-pac.html
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The Soloy appears to be addressing a different issue, which is more about redundancy for commercial operations like overwater stuff. Part of the benefit of dual engines is lost if you're just putting the power through one propeller. You're likely losing some the surface area of the second propeller even when you're turning a bigger prop than a single engine normally would. I would think that the complexity of a transmission to join the two engines into one propeller would be outweighed by just having a second propeller. The C336/337 design (and other centerline-thrust designs) pretty much give you most of the twin engine benefits without the complexity of a gearbox or Vmc roll issues.
 
Rein Hart said:
I wonder if there's demand for a new twin engine single prop experimental design for general aviation? 2 engines feeding power into a transmission for 1 prop. Some dual engine helicopters achieve this right? Perhaps a smaller version of Soloy Dual Pac? https://www.soloy.com/dual-pac.html
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What would be the primary advantage?

Twice the gas, an added failure point (gear box and transmission between two engines), failure modes were a catastrophic engine failure takes out #2.. it's a neat thought but it doesn't pass my smell test.

For what it's worth this has been done, Saunders Roe Princess, Bristol Brabazon, but hasn't been utilized in ages

$0.02
 
PS - there was a small GA 4-pax four engine pusher prop configured plane back in the 1950s.. cool little plane that aimed to address the whole the MC issue
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A simpler solution for a twin without Vmc roll would be the SkyMaster. Didn't seem to catch on though.

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WDD said:
A simpler solution for a twin without Vmc roll would be the SkyMaster. Didn't seem to catch on though.

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Didnt they have issues with always nic'ing the rear prop? Something about the take off role having to start with one engine, then bringing the 2nd engine up once there's some speed...
 
I’m intrigued by the idea of a reimagined and much better designed center thrust GA plane.

All of the advantages of a piston twin without the VMC risk. I wonder if such a plane could optionally cruise on one engine (after taking off and climbing on both) to optimize range when desired.




WDD said:
A simpler solution for a twin without Vmc roll would be the SkyMaster. Didn't seem to catch on though.

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BPM said:
I’m intrigued by the idea of a reimagined and much better designed center thrust GA plane.

All of the advantages of a piston twin without the VMC risk. I wonder if such a plane could optionally cruise on one engine (after taking off and climbing on both) to optimize range when desired.
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That’s what Routan’s Voyager did after a certain point, IIRC.
 
charheep said:
Whats a good level of hours per year, in your estimate to maintain proficiency? 75? 100? 150?
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I see what you're doing, and I won't bite. The spirit of the argument is proficiency. I doubt there are many who can remain proficient flying in general if they are doing less than 50 per year. The occasional weekend hop around the pattern, or cruise 35 miles away for a burger won't cut it. It's in the same vein as someone who gets an instrument rating but never files or flies IMC, are they really a good, proficient, instrument pilot?
 
BPM said:
I’m intrigued by the idea of a reimagined and much better designed center thrust GA plane.
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The Adam A500 has entered the chat! Burt Rutan consulted on it. They came close, they're out of business now (obviously) but I believe they actually made it through certification

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Per Flying
"The pressurized piston twin that offers safety and simplicity for the single-engine pilot."

Also from Flying
"
The centerline thrust concept with one engine pulling while the other pushes is nothing new. Cessna built more than 2,000 Skymasters between 1963 and 1980 and the push-pull twin still has many fans. But the Skymaster, though its design was focused on engine-out ease of flight, came along at a different time. The Skymaster was pushing uphill against a large fleet of conventional twins at a time when the industry believed that all twins were safer than singles, particularly at night, over rugged terrain or in instrument conditions.

Now, it’s a different environment for the piston twin. Insurance companies, and many pilots, assume that a piston twin is more risky than a single unless that twin is flown by a pilot of extraordinarily high experience, and one who receives regular recurrent training. The piston twin is the bad boy of perceived safety these days, while the Skymaster was simply, as all prophets must be, ahead of its time predicting attitudes that were to come. You will still need a multiengine rating to fly the A500, but it can be restricted to centerline thrust only so you won’t need to go through all of the Vmc control demonstrations and other engine-out maneuvers that just don’t apply to this airplane.

Back in 1998 Rick Adam correctly identified the need for a new type of twin if the typical pilot was ever going to have a chance to move up from a single, and the A500 was born. Centerline thrust with its total simplicity of engine-out flying qualities puts the question about pilot capability and experience to rest. And Rick also thought the time was right to transition to an airframe made from carbon fiber instead of aluminum or the less costly but heavier fiberglass some other manufacturers were using.
 
Thanks Tantalum! That’s exactly what I was envisioning. A beautiful implementation of center thrust.

Sad to hear they never made it. Not a rare outcome unfortunately.
 
Tarheelpilot said:
That’s freakin awesome
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They look a little more elegant on the water than on the ramp, but that engine pod on the roof is pretty eye catching. I'm sure there is a pronounced movement of the nose when throttles are advanced/retarded rapidly with the CG moment being so high up.
 
eman1200 said:
I disagree.
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I'm sure some do [disagree with me] [and/or] [stay proficient].

We are not all the same, hours aren't the end all be all, the type of flying and all sorts of stuff matters. But at the end of the day, someone who flies a few hundred hours a year inevitably has more experience than the person flying 50 or less. Especially if those 50 or fewer hours are the same breakfast run every other weekend

My $0.00
 
Tantalum said:
I see what you're doing, and I won't bite. The spirit of the argument is proficiency. I doubt there are many who can remain proficient flying in general if they are doing less than 50 per year. The occasional weekend hop around the pattern, or cruise 35 miles away for a burger won't cut it. It's in the same vein as someone who gets an instrument rating but never files or flies IMC, are they really a good, proficient, instrument pilot?
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I wasn’t trying to bait you. I am planeless now and have spent quite a few hours flying at night in a single when I had the Bo. Something about as twin would solve some reservations some of my passengers would have, and make me feel better .
A twin was always something I wanted, and kinda wanted some general direction. It was a general question to the gang, not something like a gotcha.
I was asking a genuine question, didn’t mean it to come across as mean or anything.

My highest hours in a year was 92, with a average of 65. This was with a little one at home, but i think right about 100 hours is a good balance of work, life and this hobby. Just wondering if a twin was out of reach.
 
charheep said:
My highest hours in a year was 92, with a average of 65. This was with a little one at home, but i think right about 100 hours is a good balance of work, life and this hobby. Just wondering if a twin was out of reach.
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I would suggest that, at least initially, multi engine proficiency isn’t about how many hours you fly so much as how often and thoroughly you train.
 
charheep said:
I wasn’t trying to bait you. I am planeless now and have spent quite a few hours flying at night in a single when I had the Bo. Something about as twin would solve some reservations some of my passengers would have, and make me feel better .
A twin was always something I wanted, and kinda wanted some general direction. It was a general question to the gang, not something like a gotcha.
I was asking a genuine question, didn’t mean it to come across as mean or anything.

My highest hours in a year was 92, with a average of 65. This was with a little one at home, but i think right about 100 hours is a good balance of work, life and this hobby. Just wondering if a twin was out of reach.
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ahh! sorry for my snippy response in that case! I don't think it is out of reach. 100 is a fair target, I'm currently at 80 for rolling 12 months. I'd love to fly more but it's always a time and money thing isn't it. Most of my flights are genuine trips, it's the only way I can seem to make flying consistently part of my life is if I turn them into trips. I would not say it is out of reach if you commit to the training and the proficiency, not at all. I'm also flying "easier" twins, Aztec and Duchess. I'd love to graduate to something like an Aerostar or 340, but I would want to be able to commit 200 hrs of flying per year first - and I'm just not there right now.

MauleSkinner said:
I would suggest that, at least initially, multi engine proficiency isn’t about how many hours you fly so much as how often and thoroughly you train.
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From my experience this makes sense. I did an accelerated course because that burns it into my memory better. 12 hrs of flying around on one engine you start to feel spoiled when you can actually use both engines!
 
in theory, what happens if let's say you were at 25k' and VMC rolled.......would u keep on rollin' or is it recoverable with enough room below u?
 
eman1200 said:
in theory, what happens if let's say you were at 25k' and VMC rolled.......would u keep on rollin' or is it recoverable with enough room below u?
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Interesting question. Your indicated stall speed is unchanged, but your output HP is reduced. I think you'd stall before reaching your altitude-adjusted Vmc. But let's say you have a supercharged engine, is Vmc also unchanged? I'm mindful that jets can require yaw dampers as true airspeed increases at high altitudes. Perhaps Vmc increases for the same reason if SL HP can be maintained? :dunno: I'll defer to an engineer rather than look it up. :)

In any case, yes it's "recoverable" once you have symmetrical thrust (both at idle), as in any aerobatic maneuver. Assuming you don't pull the wings off trying, say doing a split-S, or get into an aerodynamic flat spin, that is.
 
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dtuuri said:
In any case, yes it's "recoverable" once you have symmetrical thrust, as any aerobatic maneuver. Assuming you don't pull the wings off trying, say doing a split-S,
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My dad got his multi engine rating in a 310, probably 1969 or 1970, prior to Vsse existing. His instructor thought it might be a good idea to have Dad to a full power departure stall, but pull an engine just before the stall. He said the split-S was rather spectacular, and the instructor opted to terminate the lesson early.:rolleyes:
 
MauleSkinner said:
My dad got his multi engine rating in a 310, probably 1969 or 1970, prior to Vsse existing. His instructor thought it might be a good idea to have Dad to a full power departure stall, but pull an engine just before the stall. He said the split-S was rather spectacular, and the instructor opted to terminate the lesson early.:rolleyes:
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Um, CFI have a brown out?
 
eman1200 said:
is it recoverable with enough room below u?
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if you bring the power on the good engine back to idle and kill the asymmetry, yes, it should be recoverable
 
dtuuri said:
Interesting question. Your indicated stall speed is unchanged, but your output HP is reduced. I think you'd stall before reaching your altitude-adjusted Vmc. But let's say you have a supercharged engine, is Vmc also unchanged? I'm mindful that jets can require yaw dampers as true airspeed increases at high altitudes. Perhaps Vmc increases for the same reason if SL HP can be maintained? :dunno: I'll defer to an engineer rather than look it up. :)

In any case, yes it's "recoverable" once you have symmetrical thrust (both at idle), as in any aerobatic maneuver. Assuming you don't pull the wings off trying, say doing a split-S, or get into an aerodynamic flat spin, that is.
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i would not say in any case, once the spin starts you are using the rudder to overcome the moment of inertia created by the spin. with a couple of big heavy motors on the wings that is a lot of inertia to overcome. im not willing to say all twins have enough rudder force to overcome that inertia.
 
eman1200 said:
in theory, what happens if let's say you were at 25k' and VMC rolled.......would u keep on rollin' or is it recoverable with enough room below u?
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If you are prepared and proficient and get the recoveryit should be recoverable and has probably already been demonstrated in flight test. If you're slow or ham-fisted and let it develop into something beyond the initial departure then all bets are off.

Nauga,
looking up at the ground
 
WDD said:
Vmc Roll - a great idea for a menu item at a Sushi restaurant.
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Apparently, there’s a place called Sushi Lolo in Ontario CA where you can indeed order a Vmc roll.
 

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nauga said:
If you are prepared and proficient and get the recoveryit should be recoverable and has probably already been demonstrated in flight test. If you're slow or ham-fisted and let it develop into something beyond the initial departure then all bets are off.

Nauga,
looking up at the ground
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Simulators are a great place to explore this stuff. I was talking to a very experience airline guy , who is also a cfi, about twins. My concern is no experience in twins. He thought something like Scenaca would be good but to get trained and do recurrent training with an outfit like Flight Safety in a simulator.
 
PaulS said:
… He thought something like Scenaca would be good but to get trained and do recurrent training with an outfit like Flight Safety in a simulator.
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Not a bad idea…a lot of folks look at recurrent as an insurance block checking exercise.

As a new ME pilot, flying 10x a month between live and sim could be a good place to start, with a lot of that exploring the envelope and edge case ADM with a mentor MEI.
 
RudyP said:
Apparently, there’s a place called Sushi Lolo in Ontario CA where you can indeed order a Vmc roll.
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How did you find that!! Rudy for the win!
 
eman1200 said:
in theory, what happens if let's say you were at 25k' and VMC rolled.......would u keep on rollin' or is it recoverable with enough room below u?
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I know a pilot who was doing power-on stalls and had an engine fail at just the wrong time and he got to test the theory. I don't recall how much altitude he said he lost, but it was a lot more than the PTS allows for power-on stall recovery. With enough room below you and prompt action, you can probably get out of it. Some planes may be a lot worse than others, though. E.g., full tip tanks.
 
iamtheari said:
I know a pilot who was doing power-on stalls and had an engine fail at just the wrong time and he got to test the theory. I don't recall how much altitude he said he lost, but it was a lot more than the PTS allows for power-on stall recovery. With enough room below you and prompt action, you can probably get out of it. Some planes may be a lot worse than others, though. E.g., full tip tanks.
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do u know if he went into a "VMC spin" or did he just flip on his back or a full rollover or what? I would have thought unless inputs are made that you'd continuously flip over in some weird VMC rolly kind of way.
 
eman1200 said:
do u know if he went into a "VMC spin" or did he just flip on his back or a full rollover or what? I would have thought unless inputs are made that you'd continuously flip over in some weird VMC rolly kind of way.
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I think it was more of a backflip followed by a power-off split-S that I am glad I didn't get to ride along for. My understanding of the aerodynamics is that, if you just leave the working engine at full power, you'll start spinning and never stop. In a 'normal' spin, anti-spin rudder is used to break the spin. In a Vmc roll/spin, you already ran out of anti-spin rudder and stalled the vertical stabilizer, so at a minimum you need to get rid of the pro-spin engine thrust if you want it to end.
 
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