Mooney Round The World Flight Project Amelia Earhart 1937 2017

[yvesg]

Here is Brian's schedule:

 

[gsxrpilot]

He's having issues with his Stormscope and HF radio, so he's staying an extra day or two in Fortaleza to get them sorted out.

[Piloto]

Since the HF antenna runs close to the Stormscope antenna there is the possibility of damage or interference to the Stormscope receiver front end when transmitting on HF with 125 watts. Every time the HF transmit it would create false lightning strikes on the Stormscope. This can be overcome by clearing the dots after HF contacts.

The belly mounted HF antenna is not the best performer, specially on the ground. So ground measurements and tuning are not the same for when in the air. HF propagation is via the ionosphere so for best performance the antenna needs to be in view of the sky. When blocked by the fuselage the signal needs to be reflected by the ground (loosing 20db) and then back to the ionosphere. 

José

Edited June 5, 2017 by Piloto

[BCrystal]

On 6/5/2017 at 9:58 AM, Piloto said:

The belly mounted HF antenna is not the best performer, specially on the ground. So ground measurements and tuning are not the same for when in the air. HF propagation is via the ionosphere so for best performance the antenna needs to be in view of the sky. When blocked by the fuselage the signal needs to be reflected by the ground (loosing 20db) and then back to the ionosphere. 

José

Hi Jose,

Although the antenna wire is under the belly, the whole body of the Mooney aircraft becomes part of the antenna system on HF for this type of antenna. Theoretically, one can think of the aircraft body as half of the dipole, and the belly wire itself as the other half of the dipole. The radiation pattern is very different from a belly-mounted VHF/UHF antenna. So there is a more complex pattern with zenith skywave radiation on some HF frequencies while airborne.

The whole airplane (wings, tail, and fuselage) is also broadly resonant at around 12 MHz. This is mainly due to the electrical wavelengths of currents flowing along the skin of the plane from the feedpoint of the antenna out to the tip of the wings.

On most ocean flights, the angle of radiation for propagation to HF ATC (or HF ham) is usually in the range of +5 degrees to +45 degrees above the horizon. 

See the HF radiation patterns:

 

Edited June 7, 2017 by BCrystal

[yvesg]

Are those radiation patterns for a specific polarization? The way the antenna is mounted we would expect strong signal perpendically... but some of the patterns seem to approach an isotropic source which is quite surprizing.

Yves

[BCrystal]

2 hours ago, yvesg said:

Are those radiation patterns for a specific polarization? The way the antenna is mounted we would expect strong signal perpendically... but some of the patterns seem to approach an isotropic source which is quite surprizing.

Yves

The patterns are for combined vertical and horizontal polarization. 

The radiation of currents flowing on the skin of the plane contributes substantially (50% or more) to the radiation pattern.

The performance of the antenna has yielded good contact with HF ATC while in flight over the Caribbean and the Atlantic near the coast of South America.

Listen to this recording made by an HF ham radio receiver in France. It is Brian Lloyd (call sign WB6RQN) communicating on 14 MHz HF while flying his Mooney with the belly antenna, over the Atlantic, near Venezuela. The radio distance is 4300 miles (3735 nautical miles or 6920km) from the plane to the receiver in France. On the recording, 3 June 2017, he is talking with stations in USA, Europe, and South America. 

http://projectameliaearhart.org/wp/wp-content/uploads/2017/06/WB6RQN_Aeronautical_Mobile_Atlantic_Ocean_Near_Venezuela_3JUN2017_rx_F4GFZ.mp3

Edited June 7, 2017 by BCrystal

[Piloto]

3 hours ago, BCrystal said:

The patterns are for combined vertical and horizontal polarization. 

The radiation of currents flowing on the skin of the plane contributes substantially (50% or more) to the radiation pattern.

The performance of the antenna has yielded good contact with HF ATC while in flight over the Caribbean and the Atlantic near the coast of South America.

Listen to this recording made by an HF ham radio receiver in France. It is Brian Lloyd (call sign WB6RQN) communicating on 14 MHz HF while flying his Mooney with the belly antenna, over the Atlantic, near Venezuela. The radio distance is 4300 miles (3735 nautical miles or 6920km) from the plane to the receiver in France. On the recording, 3 June 2017, he is talking with stations in USA, Europe, and South America. 

http://projectameliaearhart.org/wp/wp-content/uploads/2017/06/WB6RQN_Aeronautical_Mobile_Atlantic_Ocean_Near_Venezuela_3JUN2017_rx_F4GFZ.mp3

I agree that the airframe is part of the antenna. It is always the case for any airplane antenna. But I think the antenna gain for HF is not comparable to that of a dipole or even a monopole. For optimum radiation both poles (airframe and radiating element) of the antenna need to be in view of the receiver (ionosphere). Only at this angle a strong EMF field is stablished. That is why all HF antennas (tail to fuselage wire) are top mounted.

José

[thinwing]

On 6/2/2017 at 7:44 AM, Piloto said:

That is what the bed pan with disposable bags is for. Strongly recommend it for when eating spicy foreign food. It can give you an explosive reaction with lethal gases.

José

Ugh too much information Piloto!

[Piloto]

A view of the weather for the route to Dakar.

José

[thinwing]

I guess the Belly antenna has good function listening to that recording...word gets out and he will be causing huge pile ups (numerous ham operators trying for a contact and a qso)too me that would be a huge distraction on the flight...I have too swing my beam over and give a listen on 20 meters

[Piloto]

A view of the weather ahead to Africa. If unable to circumnavigate I go underneath at about 1,000ft AGL to avoid large hailstones and turbulence. A level scope helps on assessing if you would overfly the build up.

José

[thinwing]

Looks like ITC weather!...

[Gone]

Just checked the tracking site.  Still on the ground in Brazil.  Looks like he would be battling 20-25 kt headwinds to the African coastline.

[kpaul]

2 hours ago, Ned Gravel said:

Just checked the tracking site.  Still on the ground in Brazil.  Looks like he would be battling 20-25 kt headwinds to the African coastline.

I know he is attempting the historical route, be he is going the wrong direction for the prevailing winds. 

Having spent some "vacation" time in NW Africa, I can tell you that some of the biggest storms I have ever seen (non-hurricane) were there.  At 750X250 nm up to FL 600.  you can not go around, over, or under.

[yvesg]

Looks like he did an attempt but turned back for some reason...

[gsxrpilot]

His HF radio quit working again.

[Piloto]

3 hours ago, gsxrpilot said:

His HF radio quit working again.

With the belly mounted HF antenna it is difficult to assess radio performance on the ground. On some countries you get the oceanic clearance on the ground via HF. At gross weight conditions it is conceivable to scrape with the ground the rear antenna mast on rotation.

José

Edited June 8, 2017 by Piloto

[BCrystal]

Update 18:25 UTC - 08 June 2017 -  It appears that the HF radio has been repaired by Brian Lloyd, at an airstrip in Natal Brazil. The revised schedule for the flight has not been set yet.

Edited June 8, 2017 by BCrystal

[yvesg]

He is on his way again. Lets hope all will go as planned!

Yves

[Stephen]

He's still on route @ FL24 as of this post ; maybe landfall around 4-5 PM Central on pace....ish?

 

here re is the live map link:

http://projectameliaearhart.org/tracker/map.php 

[Piloto]

He is on a good track to avoid the heavy weather. At 24,000ft the oxygen consumption is high. Wonder where he is going to refill before approaching the Pacific.

José

[gsxrpilot]

He's carrying two 115 cu tanks. He has plans to refill in Australia.

[Stephen]

Halfway there...

http://projectameliaearhart.org/tracker/map.php

[yvesg]

I just computed his ground speed from the spot data. He is doing around 137 knots. Still strong headwinds at FL240. Looking at windyty, they seem to decrease as he will approach the Africa coast.

Yves

[peevee]

3 minutes ago, yvesg said:

I just computed his ground speed from the spot data. He is doing around 137 knots. Still strong headwinds at FL240. Looking at windyty, they seem to decrease as he will approach the Africa coast.

Yves

that's just painful.