IL-62 had very simple but effective wing leading edge protrusions that eliminated the need for conventional slat mechanisms, but still achieved the effects of slats during climbing and landing. I wonder why this leading edge design did not trickle down into commercial aircrafts following the IL-62?
I see the advantages of IL-62's wing leading edge protrusions include big savings for cost and maintenance, weight reduction and allowing for bigger wing fuel tanks. Are there disadvantages that prevent that design from being prevalent in commercial aviation?
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Re: Why didn't IL-62's leading edge design become popular in commercial jets?
Today's better designed leading edges and wings have solved this entire "issue". The soviet union wanted simple, easy to maintain designs, like no slats at all and super simple high lift systems, not today's designs optimized for performance and efficiency. Having said that western wings were far from perfect back then too using wing fences and such.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
Xiiix2 wrote:IL-62 had very simple but effective wing leading edge protrusions that eliminated the need for conventional slat mechanisms, but still achieved the effects of slats during climbing and landing. I wonder why this leading edge design did not trickle down into commercial aircrafts following the IL-62?
I see the advantages of IL-62's wing leading edge protrusions include big savings for cost and maintenance, weight reduction and allowing for bigger wing fuel tanks. Are there disadvantages that prevent that design from being prevalent in commercial aviation?
Are you talking about IL-62's famous "saw tooth" on the leading edge? One of Its purpose was deep stall prevention due to T-tail arrangement. However, it has disadvantage - worse cruise aerodynamics, compared to a "clean" leading edge.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
Some might argue it was the Vickers VC 10 that was the original design or even on a smaller scale the Lockheed Jetstar which had its first flight in 1957....
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
The answer may also lie in looking at how many T-tails were newly designed after the IL-62 was put into service.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
Have You seen any il62 take off on longhaul? They needed every pound of power and every feet of runway...also approach speed was really high.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
Sort of quite different: They are so tail heavy that on takeoff they need full elevator nose down until rotation speed. Only then the yoke is moved back to neutral which is enough to make it rotate and lift off.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
Some pictures would be extremely helpful to understand the topic.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
milhaus wrote:Have You seen any il62 take off on longhaul? They needed every pound of power and every feet of runway...also approach speed was really high.
I have seen many long-haul Il-62 departures and would not characterise the type as having markedly different field performance than, say, a heavily loaded DC-8 or 707, or indeed a 747-100. We have got used to modern types, especially twins, having lots of excess power because of engine-out requirements, but the technology of earlier-generation long-haul airliners meant that most were not over-powered.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
To iRish 251: Being based at PRG I have seen a lot of Il62 taking off but none of B707 or dc8, so I cannot compare. Anyway all those aircraft were very outdated when I started my aviation hobby. And modern widebody longhaul aircraft with new modern wings did not need so compromised wing design to achieve desired performance.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
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Last edited by Gr8Circle on Fri Sep 10, 2021 9:49 pm, edited 1 time in total.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
milhaus wrote:Have You seen any il62 take off on longhaul? They needed every pound of power and every feet of runway...also approach speed was really high.
True....back in the 70s I lived close to Mumbai airport (BOM) and used to see Aeroflot and CSA IL-62s take off......compared to the 707s, DC-8s and even the 747s, they used to take off very far down the runway and would remain very low for a long time after take off.....but the engine sound was very nice and distinct.....definitely much better than the VC-10s
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
Noshow wrote:Sort of quite different: They are so tail heavy that on takeoff they need full elevator nose down until rotation speed. Only then the yoke is moved back to neutral which is enough to make it rotate and lift off.
IL -62's didn't rotate, they levitated off the runway.
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
LTEN11 wrote:Noshow wrote:Sort of quite different: They are so tail heavy that on takeoff they need full elevator nose down until rotation speed. Only then the yoke is moved back to neutral which is enough to make it rotate and lift off.
IL -62's didn't rotate, they levitated off the runway.
In this case the photographer draws attention to nose-up trim so perhaps distribution of the passenger load was also a factor.
I saw the most Il-62 activity at SNN, where at peak there could be six to ten of the type over the course of a day, taking east- and westbound flights into account. I can't recall any hair-raising departures really, but then the type was a mundane sight at the time!
Re: Why didn't IL-62's leading edge design become popular in commercial jets?
There was a famous take-off accident with some Interflug Il-62M at Berlin-Schönefeld in the summer of 1989. The pilots had pushed the yoke to the front on the takeoff run as usual, however they pushed a little too hard activating the gust lock used for parking. When close to rotation speed they could not pull on the yoke to lift off. They overran and crashed.
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