Another PSS Jet Provost Build Blog

[Andy Blackburn]

And, sorry, forgot to ask - do you know what it weighs at this stage?

[Steve McLaren]

Thanks Guys.It's not that neat really. I just choose my camera angles carefully and use an old 3MP camera so you can't see any detail!

And I don't usually build this quickly, but I want to have this flying by the 12th April. For that reason, and because I think my build is already carrying a few extra grams, I'm not going to bother with the rear wing fairings, nice though they certainly look Andy.

To answer Andy's question, it's 556g or 1lb 3.6oz, at this stage. But that's without any aileron servos or linkages, and without covering. My 2 servos will be another 30g or 1oz. And then the battery - In your flying notes you mention that the original used a 600MAh Nicad so that sounds like 4 x AAA size, or 54g (1.9oz). That would make it 640g or 22.5 oz +covering + however much balance mass I need.

I really don't have a feel for the weight of the covering, but it looks like it will be heavier than your original. But I'm still hoping for decent light wind performance!

On the covering topic - well for me it has to be the red, white and grey. That's how I remember them from when I was a kid, and that's what attracted me to this build in the first place. I'll see if I can find a reg number that isn't too common.

So yes, the ironing task is looming and I'm getting a bit nervous about that. It's all a bit more critical on a scale model., A lot of my other solarfilm covered models exhibit the wrinkling-in-the-sun problem, which Andy tells me is because I use the iron too hot. So I've got myself an iron thermometer ( the instructions which came with it also confirm the wrinkling due to iron being too hot theory) and I'm going to do a bit of research/practice before I start on the real thing. I ordered all the film a few weeks ago, but now I'm starting to doubt whether I've got the right shade of red!

Whilst thinking about the covering, I thought of another question for you Andy. You mention in the write-up that the matt black anti-dazzle panel was painted with enamel paint. Was that on top of the solarfilm, with a primer like Prymol? or did you fit the solarfilm around the black painted area?

[Andy Blackburn]

> ...mention in the write-up that the matt black anti-dazzle panel was painted with enamel paint. Was that on top of the solarfilm...

The black anti-dazzle panel was masked off, the Profilm carefully roughed up with fine wire wool and then brush painted with a thin coat of humbrol matt black enamel, removing the mask as soon as the paint was applied to reduce the paint "step" at the edge. You could do the same thing with Solarfilm using Prymol before applying the mask.

Also, I suspect that matt black Spectrum (fuel proof) enamel might be less inclined to rub off at the edges.

> ...it's 556g or 1lb 3.6oz

Well, that's only two or three ounces heavier than the original, which turned out to be just over 24 oz. So you probably won't be far off that weight, I'd have thought.

And, BTW, there's a move afoot to change the date of the ISA PSS event to later in the year. There'll probably be an announcement at the club meeting on Wednesday.

 

Edited By Andy Blackburn on 18/03/2014 13:36:29

[Steve McLaren]

During the week I painted the cockpit area and glued the canopy in place. I sealed the balsa inside the canopy with a coat of acrylic varnish and then applied a single coat of acrylic matt black ( with a bit of grey for the seat cushions - not sure if that's accurate, but it all looked a bit dull in one colour!)

I used a thin slice of the instrument panel graphic supplied by Phil Cooke, and printed on my inkjet printer, pasted on with PVA. The traplet canopies have a bit of a texture so nobody's going to be able to see it too well. Anyway it gives the general impression of an instrument panel, which will do for me.

I used 'canopy glue' to attach the canopy. I've used in on quite few models recently and it seems to work very well. My plan is to cover with solarfilm up to the edge of the edge of the canopy, and then use solartrim for the canopy lines and edges, and to cover the join.

Then I've been re-shaping my air intakes. I took a fair bit off the bottom edge, and had to narrow the under-wing fairing by about 1/4 inch each side. The result looks a lot closer to what's shown on the plan:-

So then I'm onto the covering. I've been playing around with iron temperatures a bit, before I started on the model itself. So I'm now using a cooler iron than might otherwise have done.

I have now started on some of the simple little pieces - the elevators using the grey (which is supershrink polyester). I've tried to set the iron at 100degC for the actual covering phase, but it varies a fair bit as the thermostat switches. But initial results look OK, and I would say the covering is easier with the slightly cooler iron. But will it avoid the wrinkling in the sun problem? Maybe I'll find on the 1st June?

[Steve Houghton]

Posted by Steve McLaren on 23/03/2014 20:50:26:

But will it avoid the wrinkling in the sun problem? Maybe I'll find on the 1st June?

Steve,

That pre-supposes we will be drenched in sunlight rather than rain on the 1st June!

Your head-on view looks like the pilots are already doing their pre-flight checks. I am enjoying your blog, and am impressed by the neatness of your work. I look forward to seeing the finished JP in the flesh.

Cheers, Steve H

[Steve McLaren]

A couple of weeks seem to have gone by and I've done nothing. But today I found a bit of time to carry on with the covering.

I thought I'd concentrate on the fiddly bits around the tailplane. The parts are all loose but I put them all together again to see how it was looking.

Since it's supposed to rain tomorrow, I should be able to find time to start on the fuselage itself.

[Phil Cooke]

Looking good Steve - you bringing her to the Orme in a weeks time?? I'm trying to get mine there, but slightly behind the run rate on the number of jobs left to finish her in time - I can feel a few late nights coming on this week

[Steve McLaren]

Thanks Phil.

I can't see me being finished in time for next weekend. Also, even if I was I'm not sure that the Orme would be my first choice for a maiden flight!

I spent today working on the fuselage covering. This model is certainly the most difficult I've ever tried to cover with film! After all that sculpting, there's not a flat surface or a straight line to be seen anywhere!

I decided to do each side with 3 pieces of white and then 3 pieces of red, to try to keep it manageable. This means I've got some overlap joints which (because of the slight transparency of solarfilm) show up a bit, but I'm hoping that the detailed markings will distract from that.

The most difficult bit for me was creating the curve in the red at the nose. After the covering the top half of the fuselage with the white, and after revering to various photos and drawings (including Andy's original model pictures), I drew a line on one side of the fuselage on the white solarfilm with a permanent marker. When I was happy with this, I created a matching template using tracing paper. But even this is not easy. The line on the fuselage is on a complex 3D surface. Transferring this to a 2D piece of tracing paper is somewhat approximate! But at least then I had something which should give me the same shape each side.

I then cut out two opposite shapes for each side from the film. I made them about 20mm deep at the nose and about 50mm deep at their rear end (about level with the back of the canopy). I stretched them a bit as I fitted them against the marker line, and then ironed the edge down. Then tried to stretch and iron the remainder down to the fuselage sides. I then covered the bottom of the nose with another piece - stretching to get it to fit the curvature, until it met the upper pieces. But it didn't go perfectly. I picked up a few wrinkles here and there - so I just had to iron them down hard! I reckon I could try this a dozen times and I'll always end up with the odd wrinkle! So it will have to do.

Also, after I though i'd finished, I looked at it from the nose, and decided it wasn't symetrical! So I cut another 10mm strip from the same template and went over the top edge of one side again. So I've got a lot of overlap joints, and it all looks a bit patchy. But that's probably the best I can do.

I'll be interested to hear how everyone else gets on with the covering.

[Peter Garsden]

I had the same problem when covering my Alpha Jet with the same colours (not started the JP yet as I am no where ne ar finished the build) - but one more - red, white a blue. The way I did it was also with a cardboard template for fancy zig zags. For the rest however - where it met the lines I did this:-

For the white bit at the top for example

1. Put a piece on top of the nose wrapping all the way to the mid line join and stretching back to the middle of the canopy. Allow it oversize then cut out the line of the canopy with a brand new scalpel blade on both sides and at the front.
2. Another white piece stretching all the way to the tail but jointed against the bottom of the fin - so there is one piece per side jointed down the middle of the fuselage at the top with a slight overlap.
3. Like you did a black marker line to show the join down the sidethrough the covering in white. Make the white a bit oversize so one can see where the red needs to be cut..
4. Cut the red basically to shape but oversize.
5. Lay the red against the joint, and iron it nearly up to the joint line, then using a sharp scalpel cut down the joint line and peel off the excess. This way you don't have cut a piece exactly to size round complex curves which is a nightmare. Also it avoid wrinkles if you are careful.
6. As I know you have done, cover the air intakes before gluing on, also the tail likewise.

Looks like a damn good job to me with cracking lines so well done - I know how difficult it is. My Alpha Jet you can look at on Saturday but it is nowhere near as good a job as yours. Also I managed to land it on a road last Sunday and it is undergoing cosmetic repair.

I used the method of laying on the white slightly oversize first followed by the darker colours - Lux Blue and Red over the top following the black marker pen lines - easier on mine as the lines were straighter - this is a bad picture but you get the idea.

[Steve McLaren]

Thanks Peter for the alternative method. I'm glad it's not just me that finds it difficult.

I guess your step 5 is the key one. I never thought to do it that way, but I can see how it would work. You must need to be pretty careful and accurate with the scalpel, but if you iron the film close up to the line I can see that you would get a smooth and reliable shape. I'll have to try to remember that in case I ever have to do it again.

Are you going to go for the red,white and grey scheme on your JP? I'm not going to make it for this weekend, but maybe we can compare results on the 1st June?

I might go and tackle the canopy lines now.

[Steve McLaren]

Having been shamed by Phil's work rate, I did make a little progress yesterday. I painted the black anti-dazzle patch on the nose, and added a few lines on the canopy.

You can see that I got a bit of a furry edge on the black panel. I've never used Prymol before, but I think it tends to dissolve the adhesive on the edge of the masking tape? The furry edge seems to be as much adhesive residue as it is paint. Perhaps there's a more resistant form of masking tape?

BTW what sort of pen do people use for panel line on solarfilm? I've used a Staedtler Lumocolour permanent marker, but i'm already noticing that sweaty fingers will smudge it, or wipe it off all together. Is there a better alternative?

[Steve McLaren]

Today I finished all the major covering. Now just the details to do. And the assembly of course - this is still just a set of loose parts!

[Phil Cooke]

Great job Steve - looks lovely!!

[Steve McLaren]

This weekend I did the roundels and the lettering. I decided to make my own from solartrim - partly to save a few quid but also because I hadn't done this before and wanted to find out how easy/difficult it would be.

Well, in the end, it's not too difficult, but it does take a lot of time! And the little letters are sort of fiddly!

I printed the 2 complex decals (the 'danger - ejection seat' triangle, and the 'rescue' arrow) onto self adhesive sticker paper using my inkjet printer, and then gave tham a few coats of spray acrylic varnish before cutting them out and sticking them on. I'm not sure how long they'll last, but I can always do it again if they come off in the rain. In fact I printed a bit of a stock!

It's looking finished but I've still got to glue the fin to the fuselage, and set up the aileron linkages. But the 1st flight is getting close!

[Mark Kettle 1]

Your models looking really nice Steve, home and hand made stickers look good.

[Phil Cooke]

Super - another JP is born!!!

Congrats Steve, she looks lovely. Look forward to seeing it in person on 1st June with all the rest of them too!

[Steve Houghton]

Stunning, Steve.

What a cracking job - I can't wait to see it in the flesh.

[Andy Blackburn]

Really looks the part, Steve. Nice work.

[Peter Garsden]

Sorry Steve - just seen your question - no I'm not doing the grey white and red scheme, though agree that it is the prettiest. I am doing the silver and dayglo red scheme, for one very good reason - so hopefully, I won't start flying someone else's model - I can just see it now - 300 Jet Provosts up in the air on the Orme at once - I start flying someone elses and next thing I am looking in the Irish Sea for it!

I had the same experience this winter when two different looking Phase 6 models were in the air at once. I ended up flying the wrong one. Next thing I found it 1/2 a mile away up a pine tree! It now carries my home made sticker saying "I like trees" in Chris Foss's font.

Keith, my mate, the other weekend starting flying a buzzard - when I say fly, he wasn't up there with it - he was trying to control it with his transmitter - next thing, bang, it had hurled itself like a javelin through the farmer's roof - he was very nice about it and took our £30 for the damaged roof sheet and smiled.

I rest my case.....

[Steve McLaren]

My homemade paper stickers turned out not to be a very good idea. 3 days later, I found they had peeled themselves off!

I guess the glue was just not sticky enough?

So I ordered some inkjet printable vinyl on ebay. It was only available in clear, but it seems to work. After printing, I stuck the clear vinyl decal onto a piece of white solartrim, then stuck another piece of clear vinyl over the top to make the whole thing waterproof. Then cut out and apply to model. They're a bit thick, but this time they seem to be staying on!

Today I finished my aileron linkages, and set up the transmitter programming. Then the final operation was to get it balanced. It needed a whole ounce of lead in the front of the battery box. I was a bit disappointed with this, having tried very hard to build the tail end as lightly as possible. So the total flying weight will be 26.8oz.

The forecast looks good for tomorrow, so I think I'll go give it a try!

[Phil Cooke]

Good luck with the maiden Steve!! Keep us informed on how she goes!

[Steve McLaren]

Well I managed 3 flights today and she's still in one piece. But more through luck and the strength of Andy's design, than any skill on my part!

As I said at the beginning of this blog, I haven't done a lot of slope soaring and most of what i have done has been with gentle rudder and elevator models. I fly a few 4 channel electric powered models, but this is a bit different.

The forecast today was 16 mph southerly down here. But when I arrived at the edge of the slope it felt like at least 20!

I could hardly hold the model without it flipping backwards out of my hand!

It took me about 10 minutes to pluck up the courage to hurl it into the void. Miraculously it flew! It was all a bit wobbly at first and I came to the conclusion I was trying to fly it too slow. It tended to keep dropping a wing. But after quite a few clicks of down trim it was zipping about the sky quite nicely.

Then I made the mistake of trying a turn towards the hill. Although i pulled full up elevator, I just didn't seem to have enough control, and she struck the hill with a glancing blow. The tip tanks flew off, but she was otherwise unscathed.

I had 2 more flights, one of them about 15 minutes long in which I started to relax a bit, but they both ended the same way. Each time i decided to try a landing approach, and turned towards the hill, she seemed to lose a lot of height and I couldn't pull her out in time. So 3 terrible bounced crash landings and there's not a mark on her!

At that point I decided my luck wouldn't last forever, and I should either try a less windy day or seek some advice! If I don't get to try again before the Great Orme event, I shall be watching carefully there to see how it's supposed to be done.

It is a beautiful model in the air. She looks fantastic on those fast passes. I'm just hoping to get to the stage where I can relax enough to enjoy it!

No photos I'm afraid, as I was on my own, and my hands were full.

[John A H]

Steve,

I've done the same "landing" with my JP a few times, it doesn't like to fly too slow. I think even Andy mentioned keeping the speed up in the magazine article back in 2006.

If the wind was 20mph + then the down wind leg of the landing looks very fast and the temptation is to squeeze up elevator then you end up lacking elevator authority and risk a tip stall when turning back into wind. Safest thing to do is pick up plenty of speed across the slope before turning down wind and keep a nose down attitude all the way round the turn back into wind, then only slow it down when you have the wings level on approach.

If you don't have enough height to do a "square" landing curcuit as above then a safer way is to fly across the slope out to one "side" then do a 190deg turn and let the model drift back behind you as it comes back across the slope then you only have to do a 100 deg turn back into wind. In stronger winds it may drift behind you while pointing across the slope so even less of a turn to get back into wind is required.

Just behind the slope there is often a rotor as the air curls over the edge which dumps you into the ground like a falling rock - you have to fly fast right down to the ground to have enough control authority in this is the case. The stronger the wind the worse the effect is. It's different for each combination of slope and wind speed which makes it intresting .... watch others land to see what is happening so you are prepared.

If the models is still in one piece then it's a landing ... and your ready for the Orme. If your RESCUE and EJECTION decals come off again let me know, mine have been on for over a year and I have some spares that I made at the time.

[Andy Blackburn]

There is often a rotor on the Ivinghoe south slope; if it's bad I usually walk back to the stile and land on the flat. Also, as discussed, try several clicks of down trim before commencing the approach so that if you take your hands off the elevator, it stabilises at a higher speed than normal.

[Steve McLaren]

Thanks John. I'm building up the courage to have another go. I feel I need to be in a bit more control of my landings (well any control at all would be a start!) before I can turn up at the Great Orme. On the other hand, more practice means the risk of having no model to bring with me! A bit of dilemma!

So far, the new stickers are staying put, but thanks for the offer. I'll let you know if I need some.