Archive for the ‘ random thoughts ’ Category

Feasibility of air travel on short distances

I, like many others, have been thinking the state of the current air travel system. With all the security checks and check-ins, the travel time becomes long. And easily using car, train or bus wins the passenger plane in the spent time for traveling from place A to B.

In other words, if you fly from Helsinki to Tampere, you can expect the check-in etc. to take at least 1.5 hours prior to the flight and then the flight takes maybe 0.5 hours. It might be also late, cancelled etc., and if this is a connecting flight, you may need to wait for your flight for another 5 hours sitting at the airport. On the other side you are waiting for your luggage to come, and it may take easily 0.5 hours.

So the shortest time with check-in luggage to travel from Helsinki to Tampere is maybe 1.5+0.5+0.5 hours = 2.5 hours. You may have also spent 60-70 euros for taxi from home to the airport, and on the other side the same amount of money to taxi. This makes moving from Helsinki to Tampere to be 180/2.5 = 72 km/h.

What about if this was a connecting flight that you waited for 5 hours and which was one hour late. That makes 5+1+0.5+0.5 = 7 hours. This makes the speed 180/7.0 = 25 km/h. You could beat the plane with a bicycle!

How about if you used a light aircraft to fly by yourself:
– Getting to the airport takes the same time, although it is easier to get to the Malmi airport than to Helsinki-Vantaa with public transportation without paying the large Taxi fee.
– Doing pre-flight check for the plane takes 0.5 hours. If you are quick, you have filed flight plan etc. during this time too. You may be able to speed this up if you are not flying alone.
– If the plane flies 222 km/h on average (includes takeoff and landing), taxi tie down etc. time is accounted with +0.5 hours (includes both airports), the total time to fly to Tampere would be: 0.5 + 0.5 + 180/222.0 = 1.81 hours. This is 99 km/h.

So the slow light general aviation plane is faster than the airliner on this trip. It doesn’t win use of car though, getting to the airport and from the another airport takes time. But it wins train, because in case of train, you would have to get to the train station, and get from the train station to your destination with public transportation, which adds easily 0.5 hours on both ends, even Pendolino is therefore slower than the private car on this distance, so it is not better than using the personal aircraft.

How about if the light plane was a bit faster. It would travel 300 km/h. The travel time would become 1.6 hours. This is 112.5 km/h. Actually you can save fuel on Toyota Prius if you travel 112.5 km/h. And you are sooner directly at your destination. Not bad though for the plane. Wins the airliner hands down even in the best case.

If the distance was a bit longer, it would change the other way. The private plane would be a lot faster way to travel than car. And the airline would still have the overhead associated with security checks, package check-ins, package claims etc. For example, already if you would be going to Kuopio or Jyväskylä, the personal aircraft would be faster than the private car. And still the airliner would be the loser in the speed.

If you would go to e.g. Tallinn, Estonia, then the private plane would be excellent choice. That is because you can’t go there by car, you have to use some transportation in between (e.g. boat). Even fastest boats are slow compared to even small ultralight aircraft. You could take the airliner, but it would take very long to get to the destination because of the overhead taking place at the airport. Instead if you took off with private plane, the overhead can be made smaller.

This of course requires that the plane could be flown in all weather and it would be simple to operate, with no need to do complicated tasks prior to flight in the pre-flight check. Something that would be for personal travel like a family car rather than for “flying sport”. And the plane should be very low drag and very high efficiency design to make it compete in the fuel burn with the car (competing with e.g. Toyota Prius with a plane is very tough – the fuel budget for 100 km would be about 5 liters to be equal). Many current aircraft are not like that. But I feel that there would be use for that kind of planes, and this would not be impossible.

Here is by the way a video I recorded last May in the California trip. This video is about flight from Mojave Space Port to Palo Alto.

Cirrus SR20 flight from Mojave to Palo Alto (raw footage) from Karoliina Salminen on Vimeo.

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Feasibility of air travel on short distances

I, like many others, have been thinking the state of the current air travel system. With all the security checks and check-ins, the travel time becomes long. And easily using car, train or bus wins the passenger plane in the spent time for traveling from place A to B.

In other words, if you fly from Helsinki to Tampere, you can expect the check-in etc. to take at least 1.5 hours prior to the flight and then the flight takes maybe 0.5 hours. It might be also late, cancelled etc., and if this is a connecting flight, you may need to wait for your flight for another 5 hours sitting at the airport. On the other side you are waiting for your luggage to come, and it may take easily 0.5 hours.

So the shortest time with check-in luggage to travel from Helsinki to Tampere is maybe 1.5+0.5+0.5 hours = 2.5 hours. You may have also spent 60-70 euros for taxi from home to the airport, and on the other side the same amount of money to taxi. This makes moving from Helsinki to Tampere to be 180/2.5 = 72 km/h.

What about if this was a connecting flight that you waited for 5 hours and which was one hour late. That makes 5+1+0.5+0.5 = 7 hours. This makes the speed 180/7.0 = 25 km/h. You could beat the plane with a bicycle!

How about if you used a light aircraft to fly by yourself:
– Getting to the airport takes the same time, although it is easier to get to the Malmi airport than to Helsinki-Vantaa with public transportation without paying the large Taxi fee.
– Doing pre-flight check for the plane takes 0.5 hours. If you are quick, you have filed flight plan etc. during this time too. You may be able to speed this up if you are not flying alone.
– If the plane flies 222 km/h on average (includes takeoff and landing), taxi tie down etc. time is accounted with +0.5 hours (includes both airports), the total time to fly to Tampere would be: 0.5 + 0.5 + 180/222.0 = 1.81 hours. This is 99 km/h.

So the slow light general aviation plane is faster than the airliner on this trip. It doesn’t win use of car though, getting to the airport and from the another airport takes time. But it wins train, because in case of train, you would have to get to the train station, and get from the train station to your destination with public transportation, which adds easily 0.5 hours on both ends, even Pendolino is therefore slower than the private car on this distance, so it is not better than using the personal aircraft.

How about if the light plane was a bit faster. It would travel 300 km/h. The travel time would become 1.6 hours. This is 112.5 km/h. Actually you can save fuel on Toyota Prius if you travel 112.5 km/h. And you are sooner directly at your destination. Not bad though for the plane. Wins the airliner hands down even in the best case.

If the distance was a bit longer, it would change the other way. The private plane would be a lot faster way to travel than car. And the airline would still have the overhead associated with security checks, package check-ins, package claims etc. For example, already if you would be going to Kuopio or Jyväskylä, the personal aircraft would be faster than the private car. And still the airliner would be the loser in the speed.

If you would go to e.g. Tallinn, Estonia, then the private plane would be excellent choice. That is because you can’t go there by car, you have to use some transportation in between (e.g. boat). Even fastest boats are slow compared to even small ultralight aircraft. You could take the airliner, but it would take very long to get to the destination because of the overhead taking place at the airport. Instead if you took off with private plane, the overhead can be made smaller.

This of course requires that the plane could be flown in all weather and it would be simple to operate, with no need to do complicated tasks prior to flight in the pre-flight check. Something that would be for personal travel like a family car rather than for “flying sport”. And the plane should be very low drag and very high efficiency design to make it compete in the fuel burn with the car (competing with e.g. Toyota Prius with a plane is very tough – the fuel budget for 100 km would be about 5 liters to be equal). Many current aircraft are not like that. But I feel that there would be use for that kind of planes, and this would not be impossible.

Here is by the way a video I recorded last May in the California trip. This video is about flight from Mojave Space Port to Palo Alto.

http://vimeo.com/moogaloop.swf?clip_id=2044218&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1
Cirrus SR20 flight from Mojave to Palo Alto (raw footage) from Karoliina Salminen on Vimeo.

Wing structural considerations

Martin Hollman’s book seems to describe structural calculations of wing in a pretty understandable way. Even I can follow how the resulting equation comes from the integration. I may write some software for spar sizing and layup schedule later after I get the aerodynamics part good enough to be useful. Martin Hollman’s book includes Basic language programs for spar sizing etc., but they are not that easy to convert into modern programming languages because they are full of gotos and gosubs and global variables used in a crazy manner (the traditional Basic-spaghetti way). So it seems to be easier to understand the equations first and create the calculation algorithm from scratch by myself.

However, it would be interesting to know how much weight penalty comes from high aspect ratio. I am particularly interested in AR higher than 10 where around 14 would be great, because I am interested in high flight efficiency. However, my structural needs would be for a lot higher speeds than used on gliders, so it would be interesting to know how feasible it is to achieve a structure for AR=14 that can have Va >= 200 mph without adverse effects e.g. like aileron reversal and flutter.

>Wing structural considerations

>Martin Hollman’s book seems to describe structural calculations of wing in a pretty understandable way. Even I can follow how the resulting equation comes from the integration. I may write some software for spar sizing and layup schedule later after I get the aerodynamics part good enough to be useful. Martin Hollman’s book includes Basic language programs for spar sizing etc., but they are not that easy to convert into modern programming languages because they are full of gotos and gosubs and global variables used in a crazy manner (the traditional Basic-spaghetti way). So it seems to be easier to understand the equations first and create the calculation algorithm from scratch by myself.

However, it would be interesting to know how much weight penalty comes from high aspect ratio. I am particularly interested in AR higher than 10 where around 14 would be great, because I am interested in high flight efficiency. However, my structural needs would be for a lot higher speeds than used on gliders, so it would be interesting to know how feasible it is to achieve a structure for AR=14 that can have Va >= 200 mph without adverse effects e.g. like aileron reversal and flutter.