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John Slater Airspeed Tern

Let us all watch your new project progress.
Barry Apostolou
Posts: 43
Joined: 07 Jun 2019, 15:36
Location: Surrey

Re: John Slater Airspeed Tern

Post by Barry Apostolou »

Hi Tern Watchers

Belated New years Eve wishes to all. It has been a busy time over the holiday period. With lots to do and the odd health issue. Also I appear to have been the victim of an on line 'trick/scam'. I ordered and paid for a model that was never sent, the guy that did it vanished off the 'Messenger' page' where we 'spoke', and is not responding to phone calls.

So if some one offers a Flair Sunrise gilder on line be very cautious. I suppose I was a bit naive and lost out to the tune of £100.00. Still we live and learn. I am not mentioning the guys name as I understand this is not allowed. It is a shame because he seemed like a nice chap. I am more disappointed than annoyed.

Moving on to more pleasant things, my Fair K8 and Chris Williams 1/4 scale T21 have both been flown and went really well. Now back to the John Slater Tern. The final rigging has been done and the ballast weight added to get to the specified COG. Like most vintage gliders a fair bit of lead was needed to do this, 9.00 ounces to be exact, as you may recall the under sheeting at the front was not finished to allow me to do this. So in this gap went the lead, or least 7.00 ounces of it. Two ounces were left as 'trimming weight'' to be added at the front of the cockpit so that after the test flight and dive test I could go either way with the COG depending on the out come of the test.

If you plan to build this model please make sure you keep the back end as light as possible, the all up weight has come out at 11 lb 6 oz, I don't think that is too bad (?). But with out care during the build it could have easily made 12-13 lbs. The areas to work on here are obviously all the bits at the back (rudder, elevator, fin), however the selection of material remains important, for example 0.4 mm/0.6 mm ply were used at the back and 0.8 mm was used at the front end for sheeting the fuselage. Ply was not used on the wing sheeting, I went for balsa painted to look like ply. The front wing joiner is 10 mm steel and the rear 8 mm. The nuts and bolts holding the wing joiner boxes in the fuselage were replaced with cover pieces of 2 mm ply. This saved precious weight over all. It is never one thing that saves the weight but little bits all the way through the build that do it.

The final sheeting was then added and stained to match the rest of it. I enclose a picture of this. So all that remain now is the test flight, I will keep you posted on the outcome.
All the best Barry
Attachments
Tern final Bottom Sheeting.JPG
Tern final Bottom Sheeting.JPG (20.53 KiB) Viewed 1030 times
Last edited by Barry Apostolou on 12 Jan 2020, 16:26, edited 12 times in total.

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VinceC
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Re: John Slater Airspeed Tern

Post by VinceC »

Thus is a very informative build log, thanks John. I see you gave the Tern decal on the side, any chance of sharing it so it can be added to the web page?

Barry Apostolou
Posts: 43
Joined: 07 Jun 2019, 15:36
Location: Surrey

Re: John Slater Airspeed Tern

Post by Barry Apostolou »

Hi Vince,

It is Barry Apostolou here, I am not John Slater, I am simply building his plan of the Tern, and trying to do the build log as best I can.

I will see if I can find the Tern logo and put it on line for you. It was one I lifted from the internet and used decal paper to print it off and get a water slide decal.

All the best

Barry
Last edited by Barry Apostolou on 12 Jan 2020, 16:18, edited 3 times in total.

Barry Apostolou
Posts: 43
Joined: 07 Jun 2019, 15:36
Location: Surrey

Re: John Slater Airspeed Tern

Post by Barry Apostolou »

Hi Vince,

I think I have managed to find those decals and attach the file below. The decal paper can be accessed on line. If you use an inkjet printer you have to spray the decals with a clear lacquer to water proof the inks. A laser jet printer does not need this. Then you can just float off the decals in warm water and apply them. Finally the decals are sprayed over with a clear lacquer to 'lock them in'. With the lacquer/Varnish it is best to use Matt or Satin, as gloss makes the decals too shiny, and they show the edges.

All the best

Barry
Attachments
Barry Tern Decals.docx
(42.16 KiB) Downloaded 89 times
Last edited by Barry Apostolou on 14 Jan 2020, 08:43, edited 4 times in total.

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VinceC
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Joined: 22 Feb 2015, 11:45
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Re: John Slater Airspeed Tern

Post by VinceC »

Very nice Barry, thanks

john slater
Posts: 59
Joined: 24 Mar 2015, 07:29
Location: Dudley , West Midlands

Re: John Slater Airspeed Tern

Post by john slater »

Hi All,
On my original I used ` Letter Stencils ' and sprayed a clear varnish over to seal.

John

Barry Apostolou
Posts: 43
Joined: 07 Jun 2019, 15:36
Location: Surrey

Re: John Slater Airspeed Tern

Post 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
Attachments
IMG_3273Tern Maiden JA.JPG
IMG_3273Tern Maiden JA.JPG (30.73 KiB) Viewed 966 times
IMG_3276 Tern Maiden BA.JPG
IMG_3276 Tern Maiden BA.JPG (38.51 KiB) Viewed 966 times
IMG_3277 Tern maiden fly past.JPG
IMG_3277 Tern maiden fly past.JPG (14.24 KiB) Viewed 966 times
IMG_3281Tern maiden landing.JPG
IMG_3281Tern maiden landing.JPG (23.49 KiB) Viewed 966 times
IMG_3282 Tern maiden (air).JPG
IMG_3282 Tern maiden (air).JPG (16.84 KiB) Viewed 966 times
Last edited by Barry Apostolou on 31 Jan 2020, 20:55, edited 1 time in total.

Nigel Argall
Posts: 151
Joined: 20 Mar 2015, 18:26
Location: Cornwall

Re: John Slater Airspeed Tern

Post by Nigel Argall »

Congratulations! Looks fantastic and well done for having the bottle to fly in that soup.

Barry Apostolou
Posts: 43
Joined: 07 Jun 2019, 15:36
Location: Surrey

Re: John Slater Airspeed Tern

Post 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.

Jolly Roger
Posts: 449
Joined: 30 May 2015, 20:35
Location: Sutton Bank, North Yorkshire

Re: John Slater Airspeed Tern

Post 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!

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