Kero Start Conversion On The Fleet

[Jamiem]

Over the past 3 years a friend and I have built, tweaked and generally played with 2 wren44 turbines. The first was a Synergy N9, which now has on board smoke, the second more recent addition (middle of May 2011) was a T-Rex 700 FBL V-Bar Turbine. Both machines use lots of custom machined components, and both have been 100% reliable. The Synergy has about 12 hours on it, the 700 has about 3-4 I think. I fly both machines, and fly reasonably hard 3D (although not as agressive as I fly my nitro/electric machines).

Anyway, over this past 2 months, both have been converted to Kero-Start, and while it's been a steep learning curve all over again, we seem to be getting there. The 700 has proved a little troublesome, sometimes giving failed starts, but we are getting there. We had both at the field today for a test run, and I filmed the starts on both machines

First the Synergy

[ame]http://www.youtube.com/watch?v=6DsxpXMR4tE[/ame]

And in flight in the summer, before the kero start

[ame]http://www.youtube.com/watch?v=W0iPke2WtYc[/ame]

Now the 700

[ame]http://www.youtube.com/watch?v=FxuMF998YJM[/ame]

And in flight before the kero conversion

[ame]http://www.youtube.com/watch?v=pQtBYEEWtMo[/ame]

I love them both, but probably more so the Synergy, as it was the first, and is much more unique, both because of the smoke system, and because its generally a much rarer beast

[cbdane]

Beautiful helis!! Could you share with us about the exhaust extensions that you're using? They look intriguing.

[Jamiem]

They were made by wren in the uk just a pair of small screws to secure. They discolour after every run though, so need constant polishing

[MattJenner]

how are you all getting on with the Kero option ?

I have heard mixed results, some say it is ok, others have found they have had teething problems like the jetcat, others have found them not reliable..

I am just interested how you guys are doing with them ? on either 44 or 54

Matt

[Jamiem]

It's been a steep learning curve, and not totally trouble free either, but after lots of playing with various settings, they both appear to be starting pretty well. The first start attempt on a freezing day usually fails, but then the next always starts. We can live with that as long is it is reliable.

It is a better way of starting (slower heat increase rather than the instant 5-600 degree shock from the gas), less gear on board, safer with no gas on board, BUT it does take some time to get right. Pays yet money, makes yer choice and all that

[lperagallo]

Originally Posted by MattJenner

how are you all getting on with the Zero option ?

I have heard mixed results, some say it is ok, others have found they have had teething problems like the jetcat, others have found them not reliable..

I am just interested how you guys are doing with them ? on either 44 or 54

Matt

Matt,

My two conversions have been fine. The only thing you need to do is make sure that the burner has fuel at the burner or you will have to cycle a start or prime the burner. No big deal. I have one that never needs a prime and one that occasionally needs a prime if it is really hot out. On the fourth or fifth start I need to do a prime.

As mentioned in the above post when it gets really cold (0 - 3 C) it needs to cycle twice to start. After the initial start no problems. I had similar problems with propane as it would sometime freeze. I also had the propane valve freeze open in the cold.....not a pretty sight.

All in all I think the conversion went great. I didn't have to fiddle with mine at all, but I did do the conversion at WREN USA. Chris and I were lucky enough to be the first Heli conversions in the USA. The most important thing is to make sure your battery is fully charged and can deliver the required amps. The burner draws 4 amp. Chris had the original WREN supplied Lipo and that gave up after a few starts. We are weren't sure how charged the battery was, but with a fully charged 4300mah duralite pack I get at least 7 flights before I have to charge.

Lou

[MattJenner]

Thanks Lou,
appreciate the info, and the testing you did..

Glad it is ok, i did wonder if Battery capacity/state of lypo was down to a lot of irratic starts, rather then the plug itself being at fault.

Good to know Wren have done their work once again

Matt

[Jamiem]

We seem to have the conversions pretty much nailed now The first start almost always fails (but it has been pretty cold lately), but they ALWAYS fire on the 2nd attempt, which we are happy with. We should get the 700 out for a flight or 2 tomorrow, if so, I'll get a new video shot!

[MattJenner]

Thats good to know you have Nailed it Jamie.
Weather has been great these last few days.. look forward to seeing the vid

Matt

[lperagallo]

I wanted to make sure that everyone gets some good information on Kero starting and what to look for if you are having any issues with losing the prime in the burner.

Before you start each day, check to see that there is fuel in the kero line to the burner. If there isn't any fuel then you have somehow lost the prime. There are three areas to check.

1. Make sure that the fuel is travelling through the kero solenoid is in the proper direction. There is an arrow on the valve and if the arrow is the wrong way, the solenoid will not seal off properly.

2. Make sure all your festo fittings are secure and not leaking. Any leaks will cause the burner to lose its prime.

3. Check the kero burner for a leak. Make sure that the 'O' ring at the case is secure and make sure that the kero line to the burner is snug and secure.

If you are losing your prime one of the above items is most likely your problem.

If you can't find a leak somewhere you can always prime the burner before the first flight using the HDT. Takes a few seconds to do.

Feel free to PM me if you have any questions or need any assistance.

Lou

[1hander]

great job fellas, i converted my turbine ec135 to kero start a few months ago, i have 67 starts on it for various teting and tracking and such ..and have had only one failed start whivch was due too me not priming the lines after i did a bearing replacemt. you have great helis

[gwk]

Oops wrong thread....sorry

[aviatorflyer]

Wren 44 kero start in a Trex 700. 1st start fails every time after setting for long periods of time. If flown at least weekly starts 1st time every time.

[1hander]

is the fuerl line staying primed or getting empty from sitting... you could try a littlre more voltage on the startup for the kerosene burner..

[lperagallo]

Originally Posted by 1hander

is the fuel line staying primed or getting empty from sitting... you could try a little more voltage on the startup for the kerosene burner..

You need to be very careful when increasing voltage on the kero pump. The issue with losing pime is never really caused by pump voltage. If it idles fine there is no power issue with the pump. If it is too high you will get bad starts as too much fuel might get pumped in. There is a happy medium with power and timing from the Fadec.

If you are losing your prime, make sure that you have the fuel solenoid plumbed in the correct direction and that you have no air leaks anywhere in the system.

Lou

[Wren Turbines USA]

With the motor running at idle, check to see if the fuel remains in the kero burner line, if you see it being pushed towards the solenoid ...you have an air leak. Simple as that. There is about 22 pounds of case pressure at full rpm, that will force its' way out in any direction that presents the opportunity. Hope this helps!

[1hander]

thats what was getting at.. i replaced a solenoid on the jetcat i bought used that was not seating completely, the fuel would go back into the line..it would still start on the first start, but im sure the start sequence is a bit differerent on wrens...the jetcat ecu will run it for quite a while on startup waiting for the fuel from the burner(egt to rise)..before timing out and giving a failed start..which is not good for the ceramic element im sure.

you dont want to adjust the voltage to the point flames are shooting out the rear..it gets too hot..but if his solenoid is leaking he may be able to up the voltage just enough to get the first start every time without excessive flames...

or just buy a new solenoid or replace leaking line if thats the problem, which would would be the favorible things to do definately..