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Re: John Slater Airspeed Tern

Posted: 31 Jan 2020, 18:27
by Barry Apostolou
Well guys, they do say that one good 'Tern' deserves another. Before we go any further I must apologize for the photos, clearly photography is not my strong point. Today (Brexit Friday) I flew the John Slater Tern for the first time. My flying buddy and mentor Jim Addison (wearing the blue Ozee suit) came with me to test and launch the model. We arrived at our local south westerly slope (62 miles away) to find the hill with fog covering most of it. Still, being brave (not) we rigged the model at the edge of the hill out of the wind. Jim kindly did not bring his model along so as to focus on the testing of mine. We trudged out the 100 meters or so to the launch point with high hopes. OK, first things first, the controls were checked once again, and Jim verified that all was going in the correct direction with the appropriate amount of throw. These were the throws that John S. told me to use in previous replies in this build log.

We judged that the visibility was not great so we would need to keep low and relatively near for fear of losing sight of the model in the mist. Lets go for it said Jim, OK lets said I! As a result of an overweight 'LET Minimoa' I tried to throw several years ago my shoulder is not up to launching. The idea was that Jim would launch the Tern and I would fly it out to height. Then I'd give the box to Jim and man the camera (my mobile phone) while he put the model through it paces (and I tried to take pictures). So with a final check of everything and the Volt-spy showing a very healthy battery Jim stepped forward and pushed the model out into the steady wind. I was poised (like an uncoiled spring 8-) !?) ready on the box waiting for anything that may need emergency action.

Well, no problem at all, with a dab of 'down' the Tern picked up a little speed and moved smoothly into the lift, no drama, no panic and looking all the world like a well sorted model. I did a few beats, feeling very pleased with how it felt, a little fast, but given the wind strength really good. Like a lot of vintage models it does need a good rudder hand to make the turns balanced and smooth. I un-clipped the TX and passed the box to Jim, who proceeded to test the model re-COG (dive test), control harmony, control rates etc. It looked great even in bad visibility. He looped the Tern and did some elegant chandelles, great stuff. I asked for a few fly pasts to get some pictures. (Did I mention that I am not a good photographer?) Finally it was time to land, this was where I could get a good close up (I did not).

Jim 'finessed' the model round the circuit and brought it in to a well judged landing, making sure he kept the speed up on the 'base to final' leg. What the verdict then ? Well it needed to be a little bit more positive on the air-brake said Jim. Hmm ?. I used the 255 mm electric air brakes for models up to four meters, clearly the Tern needed more. If you plan to build one I would say the 300/350 mm would be better. It was agreed that we could try raising the ailerons a little for landing. Using the 'BYFLY' setting on the TX about a 1/2 inch of raised ailerons were mixed with the air-brake.

Back on the box and Jim launched again; it flew out as before, and this time the mist was clearing so I was able to fly a little further and higher. I handed the TX to Jim who now proceed to test the new air brake set up. After doing a very nicely controlled landing he pronounced the model better, but regretted that my air-brakes were not more effective on their own. Still it is what it is ! I then was able to do three or four further flights including landings secure in the knowledge that we had ironed out the initial kinks in the handling. My first landing was a little fast as I did not want to slow it down too much, but after adding the raised ailerons on my fourth flight I was able to do a landing that I was happy with. Between us we flew another 6 flights, with Jim enjoying a lot of the flying. This was the least I could do as he gave up his flying day to help me with mine. The final verdict was that it is a great model and has given Jim more incentive to build his own. The short kit and plan are already purchased. He now 'just' has to finish a Proctor Kit, Curtis Jenny, built to a standard you would not believe.

The final reckoning being the timer on my TX showing that we had over 1 hour and 27 minutes recorded. (Take off seven minutes for launching etc), giving I hour 20 minutes of air time. Not too bad for a first session. We then celebrated the 'John Slater' Airspeed Tern with a pub lunch, remembering Neville Shute Norway, the owner of 'Airspeed' and designer of a sailplane that John's plan brought so vividly to life. Build one !

All the best

Barry Apostolou

Re: John Slater Airspeed Tern

Posted: 31 Jan 2020, 20:42
by Nigel Argall
Congratulations! Looks fantastic and well done for having the bottle to fly in that soup.

Re: John Slater Airspeed Tern

Posted: 31 Jan 2020, 20:53
by Barry Apostolou
Thanks Nigel, yup it was a bit murky, but as long as you stayed low and close it was OK, later it cleared up a fair bit.

Re: John Slater Airspeed Tern

Posted: 31 Jan 2020, 22:18
by Jolly Roger
Shame the weather didn't tern out better. ;)

It looks like a lovely practical model that should be fun to fly. Good job with the build!

Re: John Slater Airspeed Tern

Posted: 31 Jan 2020, 23:15
by VinceC
Excellent work and the weather helped create some brilliant photos. Hope you have many hours of fun and satisfaction. Thanks for your build thread

Re: John Slater Airspeed Tern

Posted: 01 Feb 2020, 07:11
by Barry Apostolou
Thanks Guys for your kind comments,

Will now take a little rest from building!. In the mean time try and get out for further winter flying.


Re: John Slater Airspeed Tern

Posted: 01 Feb 2020, 08:18
by Adam C

well done even if the conditions look dire. I did exactly the same last year but almost lost the model in fog.

My Komar is good to go now so not long before that gets thrown off a hill.

Re: John Slater Airspeed Tern

Posted: 01 Feb 2020, 09:24
by john slater
Well done Barry, very brave in the conditions you had. Very much enjoyed your build thread, and so pleased it flew as expected, you will soon get the hang of it and as you have found out without brakes landings can be very challenging.
On my first Tern ( without brakes ) I did many landing circuits before it was landed.
Kind regards

Re: John Slater Airspeed Tern

Posted: 01 Feb 2020, 13:54
by Barry Apostolou
Thank you John,

For all the help and advice during this build. More especially for producing the plan and helping me when I got stuck. It really was such a bonus having the designer reply to my questions. Yup I fully expect to get much more air time with the Tern. As you say it needs attention to get it to fly and land well, However even after a few flights I was very much at home with it. I have built a 1/4 scale John Slowcombe T46 Slingsby Swallow and the Tern is a little like this in its flight characteristics and shape.

Thank you John, All the best, keep stirring those sticks

Barry A