Pilatus PT6 Turbo Porter - Renovation

Well is seems like the Winter building season is upon us, so thought you folks might be interested in some of the many projects I have on the go !!!

As many of you already know in a few days time I reach official retirement age and with a few more pensions kicking in I decided to treat myself to the second hand Turbo Porter, which had been owned by the late Bill Marshal of the Elvington Club. Now Bill was a lovely guy and a founder member of the Elvington club and very early proponent of Turbine flying. However, he was always eager to get a model into the air so his installations sometimes (most of the time actually) were a bit rushed!

I had seen the model for the first time when Bill and I flew at the full size airshow at the old Church Fenton (now Leeds East) airfield along with other members of the Elvington Club. I didn't get a chance to look at the model in detail due to the static and flydisplay commitments but I do know that it had quite a presence and the sound of the turbo prop (Wren 44i turboprop) was spot on.

When I agreed to buy the model I couldn't get up to Leeds for some time but managed the trip a few weeks ago to collect the odel and the new Jeti DS24 to go with it (the model had Jeti Rxs in it already). I thought it would be a quick job to check the model over and get it flying. As is often the case with such purchases it is never as straight forward as first thought!!!!!!!!!

I was a little concerned about the Wing/Fus electrical connections, which were computer type plugs and sockets which had clearly been soldered up by Bill and whilst he had been careful to put heat shrink over every joint but not supported the wires other than putting a tiewrap around all the cables, one is never sure what has happened to those solder joints since they were made so first decision was to replace these. Then as you start to strip out various cables etc more and more 'I wouldn't have done it like that' starts to show up and a couple of bits of flight worthiness damage was discovered (u/c plate bent and bolt pulled out, probably due heavy landing at some time and tailplane plate/fus side cracked).

So yes you guessed only one thing for it pull everything out do the repairs and start again. So over the next few weeks and maybe months I will post the ongoing work on the PT6. Might have some useful learning for some of the beginners as well despite being a larger and more complex model.

So first job is deal with the airworthiness issues. I used slow set (for max strength) Araldite to repair the cracked tailplane mount and fus side with a reasonable fillet of the resin on the underside of the mounting plate to ensure good surface contact area. The model is a Jet Arrows ARFT (the larger of the two they make) and is covered in a white plastic film with rivets embossed into it, so I had to very carefully peal this back to gain access to the wood to ensure good glue penetration of the cracked side.

Next I removed all the undercarriage parts that I could and then the mounting plate on the underside of the model, which I then straightened out in the vice. I will make some template drawings of this so that I have some sort of way of making a replacement of it in the future if it has been fatigued in any way by the bending/straightening etc. I then used Hysol to fill the damaged bolt hole and screwed in the threaded insert into this to set. The threaded inserts go into a half inch ply keel that runs down the middle of the fuselage so the Hysol should set hard and help retain the front one, which had been pulled out.

The model has some fearsome looking disc brakes on the large and heavy wheels but most of the hardware for the brakes in the model had been stripped out. As I am hoping that I can persuade Dick Spreadbury to let me fly it at Classic Jets, I want to reinstall all the brake hardware for hard runway use, where it would just keep on rolling along at idle. I also want to try to make it capable of differential braking to aid sharpish turning on the ground, if being used as a glider tug etc. More of this later.

I will have to Be very careful when using the brakes, given that it is a tail dragger and has £4k (repalcement cost, not what I paid for it!!) of engine up front. I think the damage to the undercarriage and the absence of the braking hardware, might be an indication that at some time Bill had done a 'Brakes On' landing by mistake? With my new Jeti radio I can programme this risk out with verbal reminders when flaps and/or low throttle is selected and 'if this - then that' type programming.

Pete - Here's a thought to ponder over, is it feasible to fit a gyro into the braking system so if the tail lifts under
braking, the brakes switch off & on preventing a prop strike.
Colin.

I'm looking forward to watching the progress Pete. I'm sorry but this is already stuck in my head as the 'Pilatus Peter'.
Cannot wait to hear that turbo prop. What type/size of prop does it use?
What wing/fuz connections do you plan to use?

DaveBright wrote: I'm looking forward to watching the progress Pete. I'm sorry but this is already stuck in my head as the 'Pilatus Peter'.
Cannot wait to hear that turbo prop. What type/size of prop does it use?
What wing/fuz connections do you plan to use?

I'm also looking forward to hearing "Peters Pilatus Porter's Prop " whirring thru the Cashmoor airspace.

I also cringed at the sight of pc sourced Sub D connectors

Colin,

I have already decided to replace the Powerbox Evolution that was in the model with a Powerbox Mercury SRS. I purchased a (new in box) second hand one earlier in the week from Mark Venderveldon that he had advertised on the BMFA/JMA sites. This Powerbox Mercury, whilst the same size as the Evolution, has a built in 3 axis Gyro. As you will see in the attached pics my delivery of Satelite Rxs and various other Jeti gizmos also arrived on Friday so I am going to set the model up with Satelite Rxs and an RC power switch Rx, so that I can switch the Powerbox/Rxs on/off from the Tx. I will also be installing two 2.4Ghz Satelite Rxs plus one 900Mhz Satelite Rx giving triple redundancy with the 2 x 2.4Ghz RF boards plus the 900Mhz RF board in the Tx.

Thanks for the Gyro idea, I had not thought about using the Gyro as such a safety feature and to correct any overbraking on landing but with the very sophisticated programming capability of the Jeti and the Powerbox that should be possible. May take me some time to work out exactly how to do it as I have got to make my conversion to Jeti programming from Speky programming.

Dave,

The Prop is a Biela carbon scale prop, not sure of the size as the markings are all scale (see pic) but I will get around to measuring it at some stage. May put a wooden three blade prop on for initial test flights in case of any ground strikes, until I have got the hang of the model etc.

Bill had used the computer D plugs because there are two servos plus LED wingtip lights and he obviously wanted a single plug/socket. I ordered from Nexus a Powerbox ready wired and sealed Multiplex plug loom (bit expensive but having been bonded and sealed should withstand the constant plugging and unplugging), which I will cut to the correct lengths and then add the JR servo plugs/sockets to the cut ends. I will then use a separate JST or JR plug and socket for the lights.

Have spent the last 24 hours making new mounts for the air tanks and the fuel tanks as there were none for the air tanks and the fuel tank ones were less than neat or robust. The old tank mounts took some removing as they had been glued in with hard Balsa triangle strip, using some sort of quite brittle epoxy resin.

I have sealed the new mounts with a couple of coats of Eze Kote resin. I plan to make all mounts and fittings easily removable as in my experience gaining access for maintenance to all the complex systems in turbine models is an absolute must.

Thank you for showing the renovation work on the Pilatus.I was interested in the new connectors you're using , they'll solve my problem with plugging/unplugging all the connectors in my two piece fuselage for the Hannibal. I never thought of using those. Thanks again.

These versions of the multiplex connector look exceedingly good with a built in cable restraint.


www.nexusmodels.co.uk/emcotec-mpx-6-pins...-pairs-a86010-4.html