Hello There.

Doing my first turbine install. FB339.
Its supplied with a bypass but not sure whether to use it or not.
I was sort of thinking to use the bottom half of the bypass and leave the top half off.

What are the pro's and con's of using these bypasses as they seem available on nearly all the jet kits available these days.

Thanks in advance, Mario.

Hi Mario,

Theres no real disadvantages to using a Bypass, only a very small amount extra weight, but the advantages are all great, it will give a more direct air route throughout the model increasing Cooling, Top Speed and will also contain the excess heat of a Wet Start to a certain extent aswell.

Hope this helps.

Kind Regards

Jame

I will think its harder to monitor for a wet start with a bypass. Its being claimed that a bypass will give you higher top end speed, but without it you get better low end thrust.

Dang, everything is always a compromise, I never get no free lunch.......

I posted a pretty good list of pros and cons on this subject about 6 years ago.

http://www.rcuniverse.com/forum/m_67...tm.htm#6747797

Yes there are disadvantages, first of all you cant see the turbine, and will have no idea that you had a wet start as I discovered on a AW L39 with burnt bearers and also on some installations you can in fact reduce the volume of air the turbine needs to suck especially on larger turbines fitted in smaller models which is fairly common with guys over powering a model.

I read somewhere Jet Central stating it was not advisable to use a bypass on their larger turbines.

I don't really feel there is any advantage, it may be slightly more efficient on fuel (minimal) as the turbine dos'nt have to suck a hard with the ram air effect but that could actually cause a problem if you were going flat out then shut the throttle quickly as the ram air tried to turn the compressor faster than it wanted to go.

My feeling is there are far more disadvantages than advantages, the bottom half could be useful to help prevent stuff getting sucked in through gear doors etc, but a piece of ply or lite alum from a drinks can, will also do that.

What you have to remember is it is not in fact needed or required at all for any reason.

Thanks for all the replies.

I'll think it over but it's looking like i'll be running without it.

Mario

Although its a very good point about not being able to monitor the turbine for a wet start, we normally extend the ECU Data Terminal Lead to the front of the model (CARF Ultra Flash been a good example) and then just plug in for every start and monitor the temperatures through the start sequence, its sounds like its really just down to personal preference and although I have no evidence of Top Speed increasing with the bypass fitted, a friend with a Jets Munt Merlin 160 fitted in his Flash noticed a huge difference in Top Speed when he re installed the bypass system aswell as noticing how much more sky the model took to slow down due to the increased air flow efficiency. Just my opinion, but as I said, this was also on an overpowered sleek sport jet airframe, so the differences may be more pronounced on this type of airframe.

Kind Regards

Jame

When you point a radar at the exhaust - even when at idle, the exhaust speed is over 200 mph. Dont think it could blow it out.