FlightLink Final Fling

[stuart mackay]

Thought I would share with you photos of the final two RC systems sold by FlightLink Control before Idris Francis moved into making sticks for mobility scooters and pancake electric motors for vehicles.
The advert from RM

Sovereign Mark II and the KO Digiace (badge engineered and sold by FLC)
And here they are..

[Pchristy]

I never understood why FlightLink stuck with analogue for so long. Their mechanics were superb (sticks and servos), but the electronics was well past its sell-by date.

Analogue was always inherently problematic for model control. It did have superior interference rejection and inherent failsafe properties, but it drifted and suffered from poor centering under load. It was also a lot more complex than digital, and limited in the number of channels that could be accommodated. Even Kraft failed to make a 4-channel set work, and aside from a late effort by Sampey in the US, FlightLink were the only manufacturer to attempt 5 channels.

The only analogue system I know of that came anywhere near digital performance was the Staveley system, but even that was rapidly replaced by a Doug Spreng designed digital system.

Sadly, there are no longer any manufacturers left in the UK. At one time, there were dozens. It seems to be the same for pretty much all British manufacturing. The only truly British car manufacturer left is Morgan.....!

--
Pete

[stuart mackay]

FlightLink were the only manufacturer to attempt 5 channels.

The only analogue system I know of that came anywhere near digital performance was the Staveley system, but even that was rapidly replaced by a Doug Spreng designed digital system.

Sadly, there are no longer any manufacturers left in the UK. At one time, there were dozens. It seems to be the same for pretty much all British manufacturing. The only truly British car manufacturer left is Morgan.....!

--
Pete

Pete, interestingly, the Sovereign 2 has a revised PCB compared to the Mark 1 and if you look closely at the pic, you will see that it is configured to be a 7 channel set?
This example appears to be a 6-channel judging by the control pots and PCB connections.

[Pchristy]

I'd love to hear an audio recording of the output of that Sovereign 2 transmitter, to see if I can figure out what they were doing! Implementing more than 4 channels in an analogue set is extremely problematic! The only way I could see them achieving it would be to do something akin to the bodge done by many PCM sets ie: having priority channels that were transmitted every "frame", and less important channels (throttle, retracts, etc) only transmitted every 2nd or 3rd frame alternately.

Given that the analogue "frame rate" is already very low, and the "settling time" that would be required by the discriminators to adjust to the sudden channel switch, the latency must be very noticeable!

Many manufacturers (notably Kraft) found even four channels of analogue a struggle, and given all its other disadvantages (drift, poor centering under load, etc) it always amazes me that it survived as long as it did!

The only analogue system, that I'm aware of, that reportedly managed to overcome most of these issues was the short-lived Staveley set. I've never managed to get my hands on one of those to examine, but I would dearly love to! I've never had a Sovereign to look at either, but a few very bad experiences with FlightLink Mk1 sets made me steer well clear of them!

As I said, FlightLink mechanical bits were very good! Their servos, fitted with digital amps, were excellent. I had a FlightLink retract servo for years, fitted with a Signetics digital amp. It would certainly make for a nice 2.4 GHz conversion!

--
Pete

[stuart mackay]

Courtesy of Mike K!

[stuart mackay]

I'd love to hear an audio recording of the output of that Sovereign 2 transmitter, to see if I can figure out what they were doing! Implementing more than 4 channels in an analogue set is extremely problematic! The only way I could see them achieving it would be to do something akin to the bodge done by many PCM sets ie: having priority channels that were transmitted every "frame", and less important channels (throttle, retracts, etc) only transmitted every 2nd or 3rd frame alternately.

Given that the analogue "frame rate" is already very low, and the "settling time" that would be required by the discriminators to adjust to the sudden channel switch, the latency must be very noticeable!

I've never managed to get my hands on one of those to examine, but I would dearly love to! I've never had a Sovereign to look at either, but a few very bad experiences with FlightLink Mk1 sets made me steer well clear of them!

As I said, FlightLink mechanical bits were very good! Their servos, fitted with digital amps, were excellent. I had a FlightLink retract servo for years, fitted with a Signetics digital amp. It would certainly make for a nice 2.4 GHz conversion!

--
Pete

Pete, will go and see what I can do on the sound file.
Have got a spare Series Tx Board here if that would be of use to you for further investigation?
Do you want me to loan it to you for investigation?

Unlike your experience, I had absolutely no probs with my Flight Links in the 70s & 80s, unlike the Staveley Silver Star, that I chopped in for the Series 4 back in 71.

[Mike_K]

The only analogue system, that I'm aware of, that reportedly managed to overcome most of these issues was the short-lived Staveley set. I've never managed to get my hands on one of those to examine, but I would dearly love to! I've never had a Sovereign to look at either, but a few very bad experiences with FlightLink Mk1 sets made me steer well clear of them!
Pete

Hi Pete

I've got a Staveley 4 analogue if you ever wanted to have an investigation, but to save you the bother, there was a technical review in the Oct 1969 RCM&E with a circuit description that I've attached. It was quite complex, you can see why the Doug Spreng digital proportional caught on!

Staveley_4_Analogue.pdf

(2.11 MiB) Downloaded 127 times

[Tobe]

Whoops, we also used thise World Engines servos and I actually still have an unbuilt kit. It was my first kit I built that in those day was called micro. They would run on most receivers except Kraft Sport Series. In the beginning I used them to replace the original Bonner Digmite RS grey linear servos. Issue with Bonner connectors was that they were not polarized....and if reversed the blue magic smoke came out from its hiding place.

[Pchristy]

Stuart: Thanks for the offers! If you can get an audio file of the output, that would be great! I'm not sure the spare board would be much help. I would need to know how to connect it to all the various stick pots to get anything meaningful out of it, and wouldn't want to risk damaging it in the process!

Mike: That review was quite helpful. The designer certainly went about it in an usual way! Personally, I would have gone for two tones alternating rather than one which is on or off, with the frequency of the tones providing two channels, the mark/space ratio a third and the rate a fourth. That would restrict you to four channels, though!

Doing it the Staveley way would offer the possibility of up to 6 channels, I think. If you added a second tone generator (as I've just outlined above), that would give you a fifth channel, and if you "wobbulated" it the same way as for the first channel, that could give you a sixth. However, I shudder to think what the effect of all those low pass filters would have on latency! Latency in analogue systems is pretty high anyway, due to the time to takes to detect the audio frequencies (you need at least 10 cycles to do it reliably) plus the "sample and hold" circuits required to provide an output to the servo when it input is "off".

The complexity doesn't bear thinking about!

It certainly makes you appreciate the elegant simplicity of the Mathes/Spreng digital solution!

--
Pete

[stuart mackay]

Could that be a youthful Clive Weller acting as Idris' helper on the Spit, we need Ken Binks' opinion?
Here is the radio that was being used in the film...