Would a turbine engine encounter similar issues to a standard internal combustion engine if you were to restrict the exhaust flow by trying to extract energy from it? I mean the fact that in a car (for example), generally speaking the more you restrict the exhaust flow (e.g. with catalytic converters, silencers) the more you reduce power output - especially with high performance engines. Would turboprops/jets suffer from the same effect? If so, that could be a good enough reason not to do it, all by itself.
That would require an engineer to answer. Cars are so inefficient that restrictions probably don’t factor in (regarding efficiency). In fact, at low RPM it’s better to have some. It use to be common to have a spring loaded valve in the exhaust manifold to maintain pressure.
I really think it’s just more trouble than it’s worth to try and extract heat from an engine to keep the leading edges warm. You have to remember that you’re not heating a stationary object. The wing is basically a very large heat sink exposed to wind traveling at hundreds of miles per hour. If you’ve ever ridden a motorcycle you’ll understand how speed affects temperature. on a really hot day you get hotter as you go faster because you’re exposed to larger volumes of heated air. the same is true with airplanes. Wings are exposed to large volumes of cold air. If you remember the Air France plane that crashed in the Atlantic it was because the internal heater couldn’t handle the amount of ice that accumulated on the pitot tube.
Using an expanding bladder works at any temperature. It just pops the ice off.
That’s a good point. Some jets are more prone to ice than others and have more extensive bleed-air anti-icing demanding more and better hot bleed air.
The MD80 was especially bad that way. In heavy icing we had to carry so much power to create enough volume of hot enough bleed air to deice the whole wing that it was very difficult to descend at all. It’s poor form to extend speedbrakes in icing conditions because ice loves to form on sharp edges and you really don’t want to get raised speedbrake/spoiler panels all gunked up with ice so they won’t retract properly.
So there we’d be, up on the 30s needing to get down to the teens using something approaching a normal descent slope while needing to carry lots of power to keep the wings from getting encrusted, while also not being able to dive fast due to turbulence. So it was a mix of some speedbrakes and high power for a bit, then no speedbrakes and low power & back end forth every couple thousand feet all the way down trying to balance all the equations on average. I’m sure more than one aviation-minded passenger paying attention wondered what the heck the crazies in the cockpit were up to.
Oddly on the 767 only about 20% of the leading edge of the wing is heated. Boeing says the rest doesn’t need it.
DC9/MD80/MD90/B-717s also heat the horizontal tail (but not the vertical tail). No original Boeings heat either. Go figure.
I have a question I’ve been meaning to ask for ages, I can’t lay my hands on the copy of the book at the moment but hopefully I can remember enough of the relevant details. In The Eagle Has Landed by Jack Higgins (and reprised in at least one of his other works - he’s that kind of writer, but not much less entertaining for it, IMHO) there is a scene in which a DC-3 Dakota, in RAF livery, is returning to its German base (the Germans having earlier captured the aircraft from the British and repurposed it for this kind of covert operation) having dropped off its load of paratroopers. It is intercepted by a Luftwaffe Me-109 which naturally opens fire. The only problem the Messerschmitt has is being too fast to keep the Dakota in its sights. As it lines up behind for a second and final attack (only a few feet above the sea), the Dakota pilot decides his only chance is to suddenly drop his flaps, slowing him down even further. The Messerschmitt, taken by surprise, is forced to dive to avoid a collision and plunges into the sea. So, my question - is this in any way plausible?
Technically, yes. The DC-3 could also have created a vortice that spun the 109. The flaps may have added to it. Here’s an example of a low altitude crash from a vortice.
Someone can better explain them I just know what it’s like to hit one at 10,000 feet. It basically exceeds the roll-rate of a plane and then it’s a function of altitude as to whether you survive.
It sounds to me as if the C-47 lowered its flaps to reduce its airspeed while maintaining altitude, and that the 109 pilot was so fixated on the target that he was unaware of how low he was and dove to avoid collision.
Is it plausible? Target fixation and loss of situational awareness are common enough that I could see it happening. Did it happen? No idea.
I agree he lowered the flaps to slow down forcing the other plane to go around. but diving under the DC3 to avoid hitting it shouldn’t be a problem in a highly maneuverable plane.
Well, it’s a work of fiction, so almost certainly not. It just always struck me, as a non-pilot, as odd - for example, why couldn’t the figher pull up to avoid the collision, rather than diving into the the sea? The vortex is an interesting point that I had no idea about, it’s not mentioned in the book but it could well be that the author researched this and it was part of the scenario, with that technical detail cut in the final edit. The book in general is pretty well-researched, as far as this layperson can tell.
As described, both planes are literally only a few feet above sea level (to avoid radar), so the German fighter hits waves and perishes.
ETA: thanks for the video. Caution, propwash indeed.
IMO this.
It’s hard to shoot a slower airplane, especially with the rather short-range guns on a WW-II era fighter such as the ME-109 because you have to point the airplane (and guns) pretty much exactly into a collision course with the target, fire, and then maneuver to avoid the imminent collision.
Loosing track of just how close the ground or, worse yet, water is has killed a lot of fighter pilots over the years. We had a saying: “The Pk of the ground is 1.0” IOW, getting your opponent to hit the surface is an absolutely guaranteed kill, unlike shooting at him with guns or later missiles which sometimes hit and sometimes miss.
Trying to scrape your attacker off on the ground/water is a time tested tactic. The German pilots flying the C-47 would have been pretty top notch guys, equivalent to these modern guys/gals:
and
That is true - the pilot (singular - is that unrealistic too?) in the story was handpicked for the mission for his brilliance. Again though, it is a work of fiction.
Thank you all for once again more than satisfying my curiosity.
The DC-3, and I presume the C-47, require two pilots because they had maximum takeoff weights of more than 12,500 pounds. At least they do now. I don’t know what the rules were back then.
On a top secret mission to assassinate Churchill on the orders of Hitler himself, flying a plane in enemy livery carrying a squadron of disgraced paratroopers wearing enemy uniforms, I doubt they worry too much about regulations 
.
OTOH, there were many times when a spare pilot came in handy. 
Airplanes designed for two pilots typically carry two pilots, regulations or no. And it’s not like militaries don’t have regulations and procedures too. Although with more license to bend them in a pinch. For a truly must-succeed mission they’d more likely have trained an extra pilot just in case somebody got hurt just before mission day than done without one and launched solo.
Back in those days with those sorts of airplanes, they’d gotten mechanically complicated enough it really took two people: one to steer and one to fiddle with the knobs and valves and pumps & such and also help steer in his spare time. This increasing complexity eventually resulted in the flight engineer as a dedicated crew position, freeing the copilot to be just a deputy steerer.
IIRC, the C-47/DC-3 had some complicated rigamarole with a hand pump akin to a bicycle pump that the copilot had to pump umpteen hundred strokes to lower the flaps or raise the gear or some such. These have long since been replaced with electrical pumps on the few still-flying DC-3s. But if I’m remembering correctly, it’d have been very hard for one pilot to both fly and pump. Just one example of how these machines weren’t nearly as easy to use as modern ones.
NTSB Preliminary report on Janesville, WI crash:
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102636/pdf
It was a ferry flight for maintenance on landing gear.
…
Brian
c-47 was war-time. They could do what they wanted. Look up the crew of a Lancaster, Handley Page Hampden or Mosquito and they will list 1 pilot. And they weren’t kidding. There was only 1 set of controls. Probably a lot of British planes like that But those are 3 off the top of my head.
Incidentally, I’m glad wing vortecies travel down and not up. One year coming out of Oskosh I was still at or near the prescribed departure altitude and had a DC-3 pass below me in the same direction. That was an awesome shot of adrenaline.
@N9IWP. For completeness, here’s a ref to your first post on this mishap with a bunch of speculation in the posts that follow.
However badly a light twin flies with an engine out, they fly a lot worse with an engine out and the gear down. The temperature was nice and chilly, -14C ~= +7F. But with full fuel and two bundled up Wisconsinites even bringing just backpacks would be real close to the max takeoff weight of the airplane. It’d be easy to be over gross if they brought much luggage or were large people.
Nothing greatly wrong with their plan by GA standards, but they’d spent all their margin before they took off. Leaving nothing in reserve for any adverse surprises.
We (7 or 8 people) were out shooting astro/Milky Way overnight Sun morning at Barnegat Light. While not a dark sky location, it’s not too bad for where it is & we’re shooting to the East, over the ocean. Weather was cold, very low humidity (15-20%), & windy. As is normal, winds aloft got steadily higher with altitude*. At some point we saw a light way down the jetty, & then two. We thought someone had drones up, synched drones at that the way they were juking & jiving in apparent tandem. Eventually they moved left to right from our vantage point & then came close enough that they were clearly a pair of planes, probably going to Maguire but possibly EWR. I’m sure the planes were flying relatively steadily which means the near constant left-right / up-down motion was some optical illusion based upon weather conditions. Assuming the winds caused some light distortion from the plane’s altitude to the surface wouldn’t that be a steady distortion? What was causing the visual appearance of all that motion? Would the winds do that?
- I couldn’t get a screen cap from my phone & it was too cold to play w/o gloves on but the 10 am forecast, which was not materially different was 11kts - surface, 17kts - 1000’, 19kts - 2000’, 21 - 3000, 34 - 5000, 45 - 6000, 63 - 9000’.
Near the end of the above shoot all of a sudden there’s a really bright light to the right. Whiskey. Tango. Foxtrot! Someone said it’s plane, Ummm, no, landing lights shoot forward, not towards the rear I said. One person quickly realizes what it is (& it’s not a UFO). Not only did we get to see the Space X launch from Cape Canaveral but we got to see stage separation, too! (15x 8-sec timelapse) Definitely made the night!
Anyone have any clue why the first stage causes such a wide contrail? You can see after separation it looks more like an airplane contrail in that it is directly behind the craft.