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-   -   Wren 54 MK 2 and Mk 3 differences (http://www.rcuniverse.com/forum/rc-jets-120/2997301-wren-54-mk-2-mk-3-differences.html)

siclick33 05-21-2005 04:36 PM

Wren 54 MK 2 and Mk 3 differences
Can anyone tell me the differences between the Wren 54 Mk2 and Mk3?

What parts are needed to be changed to upgrade a Mk 2 to a Mk 3?

Where does the extra 2lb thrust come from?

Does anyone know if the Mk2 is still sold by Wren?


p.s. I know I could ask Sara but it's Saturday night and I'm impatient;)

Wayne22 05-21-2005 05:08 PM

RE: Wren 54 MK 2 and Mk 3 differences
You would be surprised at the times that they read these posts !!!

Looking at Treadstones building pictures...
-The vapourizing sticks are totally different,
-There are detail differences in the combustion chamber and how it attaches to the diffuser
-There is a new exhaust cone
-The compressor was changed from a 10 to 12 blade one sometime last year..

Several of us have had our mk2's upgraded to mk3 performance.....with Wren's help:D

ajcoholic 05-21-2005 10:21 PM

RE: Wren 54 MK 2 and Mk 3 differences
Yes some of us did :) And I certainly measured the thrust before and after, its a 2 lb difference allmost to the ounce.


TommyWatson 05-22-2005 03:27 AM

RE: Wren 54 MK 2 and Mk 3 differences
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I had my Mk2 upgraded by Wren. The main thing I noticed apart from the extra thrust is the need for extra cells on the pump battery. I used to run 3 cells on my Mk2 and get abput 90% pump power at 160000 rpm. With the Mk3, I needed to go to 4 cells to get full rpm. Also it seems to use more fuel.

Worth the money, a much nicer engine. I also got the FOD screen starter. Looks great.

TREADSTONE. 05-22-2005 03:34 AM

RE: Wren 54 MK 2 and Mk 3 differences

Tommy ..:)

...what is that airplane you have there ...;)..more pictures please..

TommyWatson 05-22-2005 03:43 AM

RE: Wren 54 MK 2 and Mk 3 differences
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It is the Bruce Tharpe "Reaction 54"

I flew it for the first time yesterday (My first jet flight). I am still smiling.!!!

HAve a look at his web site.


It is a built up model built from balsa and ply covered with monocote. Weighs about 18 pounds and spans 78" and 80" long.

Flys like an old pattern model. I call it my "Jet Kaos".

I have been building and flying models for over 50 years and this is the best I have ever had.


David Gladwin 05-22-2005 04:52 AM

RE: Wren 54 MK 2 and Mk 3 differences
Well Tommy I know you have a BVM Sabre so that may be flying soon. I flew my F86 today at the Sydney scale rally at Badgery Creek off grass, no problem at all. Now, an F86 with a SuperSport, would be even better !
David Gladwin.

TommyWatson 05-22-2005 05:08 AM

RE: Wren 54 MK 2 and Mk 3 differences

Well it has taken me quite a while to get around to actually flying these turbines I have. I must admit there was an element of fear. Could I do it?, Would I screw up?.
The Reaction 54 has put me completly at ease. Since my first flights with the R54, I have been working hard at getting the Sabre ready to fly. I just need to install the fuel system and it will be ready. I am working in Canberra for a few weeks so it might take a while.

I asked a question in another forum, about a elctronic fuel tap. Someone replied that you had mentioned a Fuel tap in a RCJI article.
Can you tell me where I can get one?.

Its good to be a Turbine Pilot not just a Turbine owner!!!


David Gladwin 05-22-2005 05:14 PM

RE: Wren 54 MK 2 and Mk 3 differences
Welcome to the fold Tom !
Wren supply an electronic fuel valve for their autostart engines, its a tiny device made by FAS from Switzerland, can be used for gas or fuel as I do in my L39.They are £39 each about Aus $95. I will be in the UK next week, can bring any Wren parts you may require.



Just seen the other post. Can't remember the valve controlled from the Tx without a servo. My belt, braces and piece of string system is as follows:

ECU controlled fuel valve
Manual Festo fuel valve.
Switch in power line to pump activated by a mini servo using overtravel of the throttle channel by using mixer activated by the snap roll button, so NO extra channel is required. This was described in my RCJI L39 article and got some very complimentary comment from the GTBA.

I think that covers just about everyone's safety requirements as far as is practically possible. !

TommyWatson 05-22-2005 05:42 PM

RE: Wren 54 MK 2 and Mk 3 differences

I have been giving this some thought and I think what I am looking for does not exist. I don't think the RX battery would supply enough current to operate a valve directly from the RX. Or it would load it down too much.
So I will probaby use your method. Makes sense and is foolproof. Any break in the wireing will stop the engine anyway. No need to rely on extra batterys etc.


Jonboy2 05-22-2005 09:32 PM

RE: Wren 54 MK 2 and Mk 3 differences
Hey. I have a wren MW-54 MKll that I bought about a year ago that has a 12 bladed compressor and one piece tailcone. From talking with Larry at Jet Hanger he said at that time wren was using that 12 bladed compressor on some of it's MKll kits which would also produce close to 14 pounds of thrust. Is there anyone out there that can verify this?? I would like to know if I have 12 pounds of thrust or 14 pounds to work with. Thanks Jon

Wayne22 05-22-2005 09:58 PM

RE: Wren 54 MK 2 and Mk 3 differences
The 12 blade compressor is only one of the elements to get the thrust increase..you may get more than 12 (particularly if the engine is a good one - well built, etc..) but may not reach 14 without the other "stuff" that is used in the mk3.....

tommyboy1229 05-22-2005 11:10 PM

RE: Wren 54 MK 2 and Mk 3 differences
Hey Tommy,

What's that big hammer for in your picture?

TommyWatson 05-23-2005 03:06 AM

RE: Wren 54 MK 2 and Mk 3 differences
The big hammer is to belt the living daylights out of anyone who comes near when I am starting the engine.!!!!

Really I use it to hammer in the rubber covered steel bars that you can see in front of the wing. It is a requirement at our field that all models be suitably restrained when starting. It is not necessary for a jet, it was just force of habit.

I have a few large gas models and I don't want to get chewed up by a 22 inch bolly carbon prop.


sidgates 07-04-2005 10:58 AM

RE: Wren 54 MK 2 and Mk 3 differences
Where do you fly the WREN in Denver? I would like to hear how you engine is performing. You can call me at 303-757-4082

volkan 07-04-2005 11:16 AM

RE: Wren 54 MK 2 and Mk 3 differences
I asked this exact question to sara:
I think you would be better off PMing Wren directly
Hello Volkan,

The mark 3 is more powerful (14lb instead of 12) and is in the smart case with a green cowl, whereas the Mark 2 doesn't look so good as the case is rolled and welded. Autostart adds almost £300 to the price of the Mark 2 and £200 to the price of the Mark 3 and, in the opinion of the Wren team, isn't always useful with a small engine like the MW54. The simple system is cheaper, lighter, easier to install and means that you get to work with the engine and understand more about the start procedure. None of the Wren team use Autostart except on the helis and turboprops.

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