Pilatus Porter Scratch Build.

by alibopo | June 21, 2014 | (9) Posted in Projects

Pilatus Porter Scratch Build.

The grass on my local flying field has not been cut this summer; they've allowed it to go to meadow, which is good for all sorts of wildlife, and, it occured to me, ideal for maidening planes - especially this one. After many attempts to get this plane in the air, it hung on my office wall for about 6 months, ignored an unloved. Well, I went for it. 'Landings' were gentler, but I still managed to go through all three of the 7x3.5 props I had with me. The plane was so close to flying I thought I'd give it one last attempt. The only spare props I had were 8x4, which were all wrong for the 2200KV motor running on a 3S battery, but I reasoned if I kept the revs down, and didn't fly for too long, it should manage. So here it is - the Pilatus Porter maiden.


Guilty admissions time...

1. I flew it with the flaps deployed, partly to keep the speed down, and partly to improve lift. The wing area is OK for this weight of plane, but not great, so I wanted the first flights to be as slow and manageable as possible.

2. I eventually overloaded the ESC. It was super-cheap, and I was hammering it with the 8x4 prop. The replacement is a lot more robust and better matched to the motor.

3. The 2200KV motor was one that was supplied in error when I ordered a 1400KV motor, rather than pay for return postage the supplier just said to keep it. It seemed to fit with the smaller prop this plane should have, so seemed ideal, but I think the props I was buying were designed for much lighter planes. Live and learn! I've ordered some much tougher 7x4 props, so they should do the job.

4. When it did fly, I was surprised how well it flew. Once I get a reliable motor/prop combo running I'll be able to work on fine-tuning the trimming-out and hopefully get the plane flying a bit slower. I kind of like the graceful aspects of flying rather than the frantic aspects.

5. Apologies, but there's no plans - this was a make-it-up-as-you-go build.

Here's some more images of the plane;

Struts are functional and made from control linkage wire with a skewer heat shrinked alongside it. This is fixed using modified Z-bends to servo arms embedded in the wing, and control horns screwed to a plate underneath the fuselage.

I used to have exhaust tubes on the nose, but they were the first thing to fall off! The flame decal used to wrap around the exhaust, which looked pretty cool, not so much now. I might add them on again once the plane is flying reliably. There's the new prop-saver. The nose is 'botched up' using foam board with paper removed from one side to allow it to bend more uniformly. It has those tiny screws holding it in place to the firewall.

There's two hatches; the tapered one has a 'spring pin' system, the back one has a simple flap with a tape hinge, and is held down by an elastic band around the fuselage.

Here's the spring-pin system. Pinching the top loop pulls the pins back allowing the cover to be fitted. Release the loop and the wire ends locate in holes in the fuselage. The wire runs through plastic tubes to keep it aligned with the locating holes.

Pinch - and fit.

The ESC goes in the front here, and the battery goes in the flap compartment behind it.

This is my 'simplified' landing gear, which replaced the fancy (and heavier) gear I created first time out.

The old landing gear assembly. Looks great, and had scale motion, but it was more important to get the weight down.

This picture shows the flap hinges and the bell-crank lever for the ailerons. A single central servo operates both ailerons through identical pushrod assemblies on each side.

Here's the flap servo and linkage, with the flaps deployed. I reinforced the front of the flap with a skewer, because it would be pretty weak otherwise.

Tail steering is as 'authentic' as I could manage. This operates from the same servo as the rudder but uses a seperate control rod. I've mounted the rods at different distances out from the servo pivot so that the tail wheel steering is significantly more than the rudder steering. This gives great manouverability on the ground. 

It's great to finally get this plane in the air, but I think if I ever built it again, I'd scale it up to maybe a 1 metre / 39 inch wingspan to get a more graceful flight. But in saying that, this plane is still very nice in the air.

UPDATE 28/03/2015 - I've been collecting and updating all my articles, planes and plans on my own website on this page; RCplanes It's still a work in progress, but there's a few extras and beta-stage projects that don't appear here on the Flite Test website yet.

All the best, alibopo.

COMMENTS

jarpy on June 22, 2014
Consider putting a blue wonder motor in it because the motor you have now is a pretty heavy for a plane that size
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alibopo on June 23, 2014
I think you might be onto something there, it is a stronger motor than the plane needs. Suggested weight range for the motor is 300-800 grams, but a lighter motor would make sense. My main issue is the ESC getting hot, I'm wondering if this is common with these 'higher revving' motors?
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Phoenix1962 on June 21, 2014
I love it! you sure have a way of making things functional. Can't wait to see what you come up with next!
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alibopo on June 23, 2014
Thanks. I amaze myself sometimes! But it's easy to get carried away and forget the important stuff like keeping the weight down. Good fun though. :)
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joyster on June 22, 2014
Cool flap hinges!
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alibopo on June 23, 2014
All those spare servo arms came in handy. The wing hinge is two shortened servo arms glued side by side with an enlarged hole through both sides. The flap arm is just a control horn. I'm still thinking about some way to get a very thin plate between the flap and the wing, to fill-in the slot that opens up.
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arborpress on June 21, 2014
Thats pretty awesome! Maybe if you scale it up you can carry the heavier landing gear more effectively. That is the coolest gear setup I've ever seen on a scratch build!
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alibopo on June 23, 2014
Thanks, comment much appreciated.
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Gryf on June 23, 2014
Terrific, Alistair! One of the challenges of building scale aircraft with foam board is making them recognizable, and you really nailed the Pilatus. It's instantly recognizable, but then the real thing is pretty distinctive. I really like the original features like the aileron linkage, flap setup, etc. really creative stuff! I'm looking forward to seeing some flight footage.

Cheers,

Gryf
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alibopo on June 28, 2014
Hi Gryf, thanks for the kind words. Sadly the aileron linkage system has proven too 'sloppy'. In reality I've probably removed as much weight as I added by using a second servo and short linkages. Also after looking at a number of 'professional' builds of the Pilatus Porter I've modified the wing to include a touch of dihedral, so I'm looking forward to a steadier flight experience. Onwards and upwards - I just love foam board, it's so versatile and easily repaired. Cheers.
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alibopo on December 4, 2014
Hi Dai, thanks for the comments. Sadly I can't take credit for the music, other than choosing it. I'm more of a UKE man than a piano man, and then just for fun. How is your SE5a progressing? I've no doubt it will fly, even with our 'heavyweight' UK foam board. Though I think you mean mm not cm - or you're talking full size there - at least :) Would you believe the SE5a is my next project too, with almost exactly the same wingspan. I'm keen to use my evolving cabane and interplane strut system seen on my AVRO 539b and more recently on my Polikarpov Po-2 (both articles on this website). I'm just finishing the drawings, and managed to get it all on 2 sheets of A1, but won't be building a test plane until after Christmas. If you've not seen my Polikarpov in flight, have a look at the flight videos in the build article and test flights article. It's a very similar wing area and a good indicator of the sort of performance the SE5a will produce. There's also various videos of the AVRO, but it's a fidgety little beast with a short fuselage and a smaller wing area. If I get calm airs it can fly slow, but if it's windy it needs the speed for stability. The SE5a has a long fuselage, like the Po-2, so it should be well mannered. Looking forward to seeing your version, cheers.
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daithespy on December 4, 2014
Well done, Alistair, you're obviously an excellent engineer, and a bit of an inventor thrown in too! I enjoyed your maiden video, not just for the flight footage, but also for the evocative music. Did you create that too? I noticed your keyboard in the background of some of the photos. I'm just starting out in this hobby, and making forward and backward steps as well, as I figure out what I can, and cannot do with foam board. My first project is slowly taking shape. It's an SE5A, with a 950cm wingspan, and as I only have a couple of Dollar Tree foam boards from the US, most of it is made of the heavier, stronger stuff we get in the UK. Only time will tell if it's airworthy!
Cheers,
Dai
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Pilatus Porter Scratch Build.