Tuesday, 21 August 2018

Oil thermostat failure

On the last leg of my month long trip I noticed that the oil temp was not coming down as it normally does once in the cruise.

It stayed at 100 - even though I was at 7,000 ft.

I put it down to a particularly hot day and perhaps a strong inversion over the UK which made it unusually warm at altitude, which it was.

However on my next flight, after the 50 hour service, it was a coldish day and I did not climb for long but the oil got hot again (106 - the hottest it's ever been) and refused to come down below 100 when in the cruise.

I thought this must be the thermostat (in the oil filter mounting plate) which had failed and was now stuck in the closed position. This has also happened to Pete Wells - while he was in Spain in the summer - not good!

I contacted the UK UL Power agent, Jonathan and after a discussion with him he agreed that I should replace the part and see if that was the problem.

UL Power were good enough to send me the replacement part which arrived this morning. I fitted it this afternoon and then took the Twister for a test flight.

I'm pleased to say all is now well again and the oil temps are back to their old self. Not even hitting 100 in the climb - despite a hot day again today - and then coming down to 90 in the cruise - as it should.

Lucky this did not happen to me while I was overseas as it would have grounded me while I waited for the new part to arrive.

After the old thermostat/oil filter housing was removed

New housing at left and other old fittings to be reused at right

Old thermostat. Note the spring is not seated the same as the new one - maybe this has something to do with it failing?

New thermostat spring - note the more even seating of this one.

Old housing to the left and new one to the right. The valve also appears to be slightly more open at ambient temps on the new housing too.

Sunday, 12 August 2018

Belgium, The Baltics and Beyond

I spent the month of July touring in the Twister.

The journey began in Belgium with a great weekend of banter and beer at the EFLEVA (European Federation of Light, Experimental and Vintage Aircraft) fly-in where I was asked to give a talk on my Oshkosh adventure from last year.

It was good to catch up with Johan and we took an early morning Twister formation flight together the next day.

Then it was off to Germany to visit Paderborn Haxterburg and the home of the Twisters. Another memorable formation flight followed with Matthias and Ingo in Twisters 2 and 3.

The next day I flew to the north eastern part of Germany, to Anklam. To visit the Otto Lilienthal museum and the following day take the short flight up to Peenemunde to visit the V1 and V2 museums.

The next day I headed east to Kaunas in Lithuania, via Gdansk in Poland and skirting the Russian border of Kaliningrad to the north.

I then spent a few days in each of the Baltic countries - which I fell in love with. Each one has it's own unique flavour, plenty of history, culture, interesting foods and they are all very affordable to visit. Highly recommended!

While in Riga I visited the Tarragon factory and took a test flight in the prototype Tarragon - a very impressive machine.

I flew into Tallinn International in Estonia - as there are no small airfields within reasonable distance of the capital. 

After that it was north through Finland, overnighting in Kemi. Then up to Lakselv in the north of Norway, flying via Europe's northernmost point, Nordkapp, which I did not actually get to see as it was covered in coastal fog.

As it is so far north, morning civil twilight in Lakselv begins on 26 April and evening civil twilight begins on 16 August. In between these dates it being light all the time.

By flying around Nordkapp I was at 71 degrees North Latitude, much further north than my trip from last year which was just 67 degrees north in Kangerlussuaq, Greenland. I think this is the most northerly point a Twister has ever been?

After that there was only one way to go, South. I headed to Bodo for two nights. One afternoon spent looking around the excellent National Air Museum of Norway, which is located at the Northern end of the runway in Bodo. The next day was a highlight as I took a short flight over to the Lofoten Islands which are quite spectacular. I stopped in Leknes airfield and took the bus to the Viking Museum.

The next day I flew two long legs, the first south to Trondheim for a fuel stop then east across to Stockholm where I stayed with my friend Chris for 5 days and a well earned rest.

Heading back west to Oslo after that and then across to Bergen after 2 days in Oslo. 

My partner Tracy flew over to Bergen and we did a road trip around the fjords for the next 4 days.

A short flight south to Stavanger via the spectacular Lysefjord and then it was across the north sea to Eshott for fuel and then south back home to Old Warden.

What a great trip and I was so lucky with the weather.

44.2 hours flown in total. Fuel burn average 14.8 litres per hour with a total burn of 654 litres.

The only problem being a flat tyre in Bodo after landing. Not sure why it went flat but I think maybe the pressures were a bit low.

Pics and a few vids on this link: https://www.flickr.com/photos/andymac53/albums/72157694156800820/page1 

Route map

The F word

No not that one. Flutter.

Recently I noticed that the elevators had a little bit of play in them. 

The port side was much worse than the starboard. 2.5mm measured at the trailing edge but less than 1mm of play on the starboard side.

The play was all coming from the Hex in the elevator, the female part of the elevator connection, which slides onto the ali male hex on the elevator tube.

Consulting Matthias about this he said just to wax up the metal part and then put flock into the fiberglass hex part and slide the tailplanes back on and let them cure.

So that's what I've done and this has taken all the play out.

When I was on my recent trip in the cruise at altitude I found I could induce a little flutter of the tailplane by very gently 'polling forward' on the joystick. Not good. 

I went for a test flight yesterday after fixing the play and I'm pleased to say - no more flutter.

Something worth checking.

Video of the port elevator play below.

Tailplanes off for the elevator hex fix.

Metal hex and surrounding area all waxed up so the flock does not bond to it.

The fibreglass hex inner was sanded and then cleaned with Acetone before applying a thin layer of flock to take out the play. The hex was also inspected carefully to see if there was any cracking or other damage but all was well.

Sunday, 5 August 2018

Twister Database

I thought it would be a good idea to put together a database of all the Twisters that have been completed and have flown (or are just about to).

If anyone finds any errors or omissions I'd be pleased to hear from you.


D-MTMH. Number 2.

D-MTMN. Number 3.

Diesel Twister. Registration unknown. Damaged in accident, no longer flying.

F-WTVI. Written off in post crash fire.

G-CDKJ. Sold to Germany, currently being fitted with a D-Motor and re-registered as OE-CSI.

G-FUUN. Number 28. First flight 11th December, 2016.

G-JINX. Damaged in crash landing, currently being rebuilt to flying status.




G-TWSR. Number 5.



G-ZWIP. Number 4.

I-A908. Italian registered, Built by Termikas in Lithuania.

LY-BDA. Electric Twister, built by Termikas and Silence Aircraft. Resides in Switzerland.

LY-ING. No longer flying due to owner health issues.


N600ZF. Number 6.

N787M. First kit sold and constructed.

OO-162. Number 31. First flight 19th June, 2016.

Registration unknown. Fitted with D-Motor. Flight status unknown.
D-MTMH. Twister Number One, the original prototype. Note Twister Number two uses this same rego. This airframe is no longer flying.

Making the pilgrimage

During my recent European trip I finally made the 'pilgrimage' to Paderborn Haxterburg and the Silence Aircraft factory.

Upon arrival, Matthias was a little delayed due to traffic so I took the time to look over Twister Number 3, D-MTMN with Ingo, who showed me some of it's unique features and the summer canopy option - convertible Twister!

After watching Matthias and Ingo put together D-MTMH in just 6.5 minutes all three of us went for a nice formation flight over the local area and flew over the Silence Aircraft factory. We also circled over Thomas Streikers house and he took some photos of us in formation on his phone.

Later on that evening I had a great discussion with Thomas and Matthias over dinner and beers.

Matthias kindly put me up for the night and then the next morning we spent 3 hours at the factory - which is an impressive set up with much going on. 3 new prototype aircraft were in construction - but I am not allowed to talk about them and could not take pictures of them. Suffice to say 1 of them is rather interesting.

Lots of pics below...

Flying over the Silence Aircraft Factory
Taken by Ingo in Twister number 3.

Taken by Matthias

One of only 2 photos I took during our formation flight as it was during the hottest and most turbulent part of the day - hence the rather loose formation.

Rotating base of this hangar allows each plane to face the door without moving any other plane.

D-MTMN - Twister Number 3 and still clearly a prototype.

Fuel marks in tanks allow easy checking of levels before assembly.

Notice the different wing spars - this is a German microlight version only and not as strong as the later kits which have a different spar for aerobatics.

Home made propellors - covered with a thin layer of fibreglass then polished to a mirror finish.

Cowl flap for variable cooling. Closed position.

Cowl flap for variable cooling. Fully open position.

Note the heavily reinforced hinge area - retractable Twisterarti take note!

Ingo's headrest solution - very lightweight.

Convertible option - made from an old smashed up piece of glider canopy.

Despite the reinforcing and lighter weight of this aircraft it still shows signs of cracking. A weak point for sure.

Canopy hinges are completely different to other models too. Ingo talked to me about replacing these with the long hinge as per the later models as these ones are not that good.

Matthias and Ingo put together a Twister in 6.5 mins.

I noted that the pitot tube on D-MTMH was much further inboard than the manual recommends.

All done in just 6.5 mins

Taxiing out for our memorable formation flight.

Matthias heads over to the industrial area to overfly the factory.

I noticed the static port on Number 3 D-MTMN was in the position shown by my finger. So it's quite different to the position on G-FUUN. My testing has revealed that my airspeeds are very accurate though so I think my statics are in a good position.

Matthias and 3 of his creations.

Matthias takes me for a tour of the factory.

Twister Number One - the original prototype with a liquid cooled rotary engine. It seemed to me to share almost no common parts with the later production versions.

V-props. Designed and built by Silence they use a similar system to the Pilatus P2 - an air driven front spinner section which automatically regulates blade pitch depending on airspeed.

One of the few things I could take a picture of in the factory. The owner has a Bizzarini that he races at Le Mans in the historic series and wanted spare body panels. So Silence Aircraft have made molds of the body and are making spare panels for him.

A static model of D-MTMH - about 1/6th scale.

The panel from the original prototype number one with it's rotary engine.

A spare safety cell hangs in the factory.

Huge CNC machine.

Lots of spare Twister parts and the molds in the background

More molds and parts.

It seems G-FUUN has become a star in the office area of the new factory.

Matthias particularly likes this pic of G-FUUN, taken on the Bonneville Salt flats last year. It sits in pride of place in his new office.

The boardroom.

Part of the wing from the Diesel Twister

What remains of the Diesel Twister.