Laminar Flow Control

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In some TV program they said that during World War I - in two-seater airplanes - the pilot flying alone had to take a sandbag as ballast. Then the designers changed the pilot's seat and the problem was solved. Can you explain to me what this is about?
 

You've got it backwards.
In early WW1, most 2 seat aircraft had the pilot in the rear, the observer was ( with a gun maybe) in the front.
That way if the pilot had to do no CG adjustments, if he flew solo, because the front seat was at the approximate CG.
But I'm sure you can see the problem with the observer up front , right under the wing where all the support struts are.
A bad combination when trying to shoot a MG.
So they eventually got smart, put the pilot up front, the observer in the rear, where he had a better location for using a gun.
But these early aircraft didn't have a adjustable stabilizer to compensate for a changed CG. So the aircraft with the pilot in the front had to add weight to the rear if they flew solo.
Look at a early WW1 BE-2, most had the pilot in the rear, late war BE-2s and most other 2 seater aircraft had the positions changed.
 
MIflyer said:
You use the trim for level flight adjustments. And if you do the CG calculations and the passengers put you outside the allowed envelope, you do not let them get in the airplane.

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Ive been on a few flights in small aircraft (Short Skyvan type) where passengers have been asked to move from the rear to the centre.
 
Most ww1 aircraft that I've seen didn't have any form of trim system, so the elevator authority was limited. During ww1 this wasn't a problem, as the only time you'd be flying a two seater aircraft alone would have been ferrying it, or a test flight.
 
MIflyer said:
You use the trim for level flight adjustments. And if you do the CG calculations and the passengers put you outside the allowed envelope, you do not let them get in the airplane..
Click to expand...

So another question. It has always interested me. How do pilots solve the ice problem on the windscreen inside the cabin? As a driver, I know that the ice outside is less of a problem - you can cover the windscreen with a fabric or use different substances. But inside the car, that's impossible (these substances smell a lot and drip onto the inside). And pilots must have some solution to this problem, because in war movies they often (after an alarm) run to the plane and have clean windows, no ice.
 
About any military aircraft has a ground crew, crew chief, etc.
Guess who cleans the windows, and a thousand and one other tasks on the aircraft to keep it mission ready ?
And once he's airborne, most aircraft meant for high altitude flight has very good defrost systems.
 
tyrodtom said:
About any military aircraft has a ground crew, crew chief, etc.
Guess who cleans the windows, and a thousand and one other tasks on the aircraft to keep it mission ready ?
Click to expand...

I have no doubts - when it comes to planned missions. But it's hard for me to imagine that there is always someone sitting in the cabins at the airport scraping ice from the windows. There must be some other "smarter" way here. And what does the owner of a private plane do? Also scratches the ice inside the windscreen and the ice falls on his seat? No, that's too stupid. There must be some wise solution to this problem. Additionally, my guess is that the windscreen in airplanes can be "a bit" more expensive and complicated than in a car and such an expensive glass must not be scratched with a tool (even some car owners find it too risky).
 
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I'm not sure you're reading my whole answer.
Nobody scraps ice off plexiglas windows.

I've never owned a private plane, but I have rented them.
If the weather is so bad you're having a hard time getting the aircraft ready to fly, you probably shouldn't even be thinking of taking it off the ground.
Because once you're airborne it's likely to get worse.
A lot of people have died ignoring that fact.
 
Odoaker said:
How do pilots solve the ice problem on the windscreen inside the cabin?
Click to expand...

In a typical jet aircraft. hot, high pressure bleed air is taken from the compressor section of the engine, cooled by running it through a heat exchanger that uses ram air from outside, and then expanded through a cooling turbine to produce cold air. The aircrews then mix in some of the still hot bleed air to attain a suitable cockpit temperature. Typically, after the cold air comes out of the cooling turbine it is run through a water separator, which is kind of like a perforated funnel with a cotton sock over it.

Now, how does that prevent the canopy from fogging up when the aircraft descended to lower altitudes? Well, sometimes it does not, the F-4 being an example. This was surprising considering that the F-4 is unique in that it has two air conditioning packs, one for avionics and one for the cockpit. But the reason it has two is that when they added the 2nd seat and added the Sparrow missiles as the primary weapon the only room they had available was the place where the 20MM guns were supposed to go. Now, the air conditioning system will eventually clear out the moisture, but if you have just turned final "eventually" may be far too long.

Hot bleed air is also used for rain removal by blowing it across the front of the windshield. I had some "fun" figuring out what was wrong with an F-105 rain removal regulator that would turn into a foghorn when it either needed some special adjustment or we had a technician running the test cell decide to ignore certain set-up details.

On some aircraft they put a very thin layer of gold across the windshield and pass a electric current through it to keep the transparencies warm enough to get rid of any ice.
 

WW1 ground crews were up and about well before pilots, getting the aircraft ready. Ice accumulation on the ground wasn't really too big an issue, it only forms in the presence of visible water vapour (cloud/fog), so if it was forming while you were waiting, you were grounded due to the visibility anyway.

I've never seen ice on the inside of a modern aircraft windscreen, the humidity is generally too low inside the cabin for visible vapour, so no ice. Modern aircraft do have heaters, just like cars and this can normally be redirected onto the screen if needed.
 
As far as I know the planes of that time (WW1) had open cockpits (only windscreen) so the humid and warm air probably didn't collect inside and it didn't condense on the windscreen. I mean, for example, Bf 109 used in winter.

gumbyk said:
Modern aircraft do have heaters, just like cars and this can normally be redirected onto the screen if needed
Click to expand...

But how fast does the engine warm up and you have warm air? From my experience: after 15 minutes of driving, not earlier. Often, warm air appears when ... you don't need it anymore because you've just arrived at your destination Maybe during the war they put some kind of electric heater in the cockpit and it was warm all the time? (at least, warm enough that there is no ice inside) ? But where to get electricity for such an electric heater under Stalingrad? Also a weak theory ...
 
XBe02Drvr said:
If you're trying to make a hand launch glider to fly at hand launch speeds, weight is your enemy. "Absurdly light" is a basic requirement.
Click to expand...

However, I did notice a problem with that light models (made only of thick paper + small metal ballast). They are very sensitive to the wind. They fly nice, but only indoors without wind. There is no point in using them outdoors, as they are in the air for quite a long time, but the flight direction is completely random. How did you solve this problem with your models?
 
It's almost immediate - most light aircraft have the heat exchanger off the exhaust. If your car takes that long to warm up, you need to check the thermostat; I've just done the school run - 4km total, and the car was a operating temp well before I got home.
Honestly, it's not a problem as you seem to think it is. You may get some condensation, but in my experience, even with a good frost on the outside, there isn't ice inside the windscreen.
 
There is no way to answer questions accurately with such wide reach.
WW1 ? WW2 ? Civilian aviation ? Military aviation ?

Then to how did they have flight operations in Stalingrad, in the winter .
Everything on the Eastern front was primitive, to start the engines in the cold they erected tents around the engine, and built a fire under them.
Sometimes the Russians thinned their oil with gasoline, set the gas on fire . When done right, in the extreme cold that would only heat the oil up enough to flow and let the engine turn over. When done wrong, as I'm sure it happened sometimes, it resulted in a big fire, and maybe a execution .
Finally the Russians squeezed them down to such a small area, they didn't have room left for aircraft to land.

And then back to a home made model glider ?
And none of it has anything to do with laminar flow control .

You might need to move this out of the technical section to another.
 
Light aircraft are mostly air cooled, so all that needs to warm up is the thin metal assembly that acts as a jacket around the exhaust manifold. And since they are air cooled they is no water to warm up, either. Note that before takeoff for carburated engines we check to see if the carb heat is working; if it is not working because things have not warmed up enough, you run the engine until it does.
 

So maybe it's just some particular problem with my car. In fact, the other two cars in my family have this problem less. But I figured it must be a hassle for a pilot when he is ordered to jump on a plane and fly immediately. And I heard a soldier's story about how in his air unit there was suddenly such a training evacuation of all planes. Many of them were completely unprepared to fly, but an order is an order. The idea behind the exercises was that World War III suddenly began and the airport would be destroyed in a moment. The unit that evacuated more planes within the specified time wins.
 
As I understand it, aircraft were run up at the beginning of the day by ground crew, to ensure that they were ready to go.

Jet aircraft are a different story, you can just get in, start it and go. Piston aircraft need to be run up to ensure that they are making adequate power.
 
gumbyk said:
As I understand it, aircraft were run up at the beginning of the day by ground crew, to ensure that they were ready to go.
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I'm afraid not necessarily. The soldier said that the mechanics and pilots were terrified and that some planes had numerous technical problems during take-off - precisely because they were not prepared. But the Soviet command was not worried about the lives of the soldiers. The generals were proud that the planes took off quickly under conditions of total surprise.
 
I was stationed at a Seymour Johnson AFB , NC, in 1966, a SAC base.
They would have alerts where all the B-52s and their tankers had to get in the air within a certain specified time limit.
I don't remember what that time limit was.

But when they occurred everybody for miles around knew it.
My barracks was over a mile from the SAC ready pad, when those 12 or so B-52s and a tanker each started up, we had to yell at each other to be heard over the noise.
And in the back of your mind was always the thought , is this just a drill ? or ???.

If it was a drill, they called it off when all the B-52s reached their assigned altitude, and location for refueling.

The tankers would come back first, that's when we'd be sure we weren't all about to become crispy critters.

Just one failure to successfully get all the aircraft in the air within that time limit would at least result in the relief of the squadron commander.'
There were no excuses accepted.

That was how the USAF did it in 1966, I have no idea how the Soviets did it.
 
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