suttonr,

There were two different articles in RCJI magazine 2-3 years ago about pipes and in particular the Wren augmented pipe. It would be worthwhile reading for you. My take-away was that a properly sized straight pipe with the right gap can yield zero thrust loss. A Wren pipe done right can give a 5% thrust improvement.

I just completed some preliminary balancing on my F-16 and it looks like I will need about 24 oz. of batteries in the nose to balance it. I plan on putting redundant receiver packs and a nicad ECU battery up there. The plane will come out a little over 20 lbs.

If I had put the engine in the tail I'd need a lot more nose weight. It would really help if FEJ could make some changes to reduce the weight in the back of the plane. As jetmodeller pointed out earlier in this thread the supplied tailpipe is rather heavy (13 oz.). They could have used substantially thinner stainless for the outer wall and saved a few ounces. I'm not sure it is worth the extra cost of buying another pipe though.

Joe

My advice to anyone building one of their F-16's is to mount the engine as far forward as possible and lay out your components to shift as much weight forward as you can.

Joe

If you are designing a pipe from scratch, this is valid, but Wren did all the design work and a lot of testing, and it's not something you have to take into account when you buy a Wren pipe. It's important that the exhaust nozzle isn't too close to the pipe otherwise excessive air will be sucked in, choking the pipe. Our engines operate perfectly well with the exhaust nozzle 30mm (1 and a quarter inches) from the pipe. Increasing the pipe diameter beyond the optimum size doesn't give any thrust increase. For instance, if using a 44 with a pipe designed for a 54 the thrust actually goes down slightly.

Sara Parish
Wren Turbines

Seems like a turbine in the tail (super bee or P60) might be a stretch on this f-16. With weights pushing 20 lbs and it being tough to balance it seems like it could lack performance. Seems like the conventional mount is the way to go.

Rich

Mr dj, i read with interest your post, but the point of us all on this thread is to learn how other people have got over problems so that we do not do the same thing whether we chose to listen to other people,s advise is up to the person involved.i have been involved flying turbines for 12 yrs,i built my own turbine because you could not buy one ready to run in those days,if you chose to fit a Falcon and do not listen to good advise thats fine,but have you heard the saying "I told you so"lets not spoil this thread with this sort of posting and get on with what we all like doing and thats flying and building model Jets,please no more banter its just boring regards Keith

Rich,

That's the conclusion I came to. I debated whether to mount my Wren SS in the tail or conventionally. I weighed the various components and measured their distance from the CG for both conditions. After a few simple calculations it told me that the plane would come out slightly heavier if I mounted the engine in the tail.

A P-60 or Super Bee are about 4 oz. lighter than my engine, so with one of those it might come out a wash or possibly slightly lighter in the tail.

Joe

Hello Joe,
I have a simjet 1200, as your wren S/S, i make the same conclusion as you. With the simjet in tail position (same weight than SS) the F16 is 400 grs heavier than conventionnel position.
Tail position is good for P60/Super bee only. For other conventionnal postion is better.

The 54 clas engine (as wren SS, simjet 1200..Etc) is the best choice for this F16.... a KJ66 clas (P80, 120, Falcon etc) is very heavier, more fuel, too trust, .Etc... wrong choice... The biggest is not the best...

Regards,

Sébastien

Keith

Obviously you read negative words in my writing that’s not there at all. And I’m not going to go toe-to-toe with you either… “I told you so� is a bit childish for my 49 year old self… Sign Guy agreed and understood in a kind way what I said—he asked a question and I answered it—and I did it in a mature way as to not upset anyone reading this thread…

Mike Denilin, what’s going on? You made it back to the world in one piece—Kool Beans. So tell me, any mail coming my way soon?

Thanks…

Mr DJ

Well said Sebastian,that,s three people that have said that the Falcon is the wrong engine for the F16,hope you get the drift, sign guy regards Keith

Sign Guy, what up…

I hear you about going with what everyone else has—for many, that’s kool. I don’t mind being the odd ball out—in fact, I like it. Many birds in my area have JetCats—kool—I bought a SimJet Nexus for my YA-15. Falcon for my FEJ F-16; Super Bee for my ShokJet; nothing yet for my FEJ Rafale (maybe a Wren); and maybe a pair of P160s or Rhinos for the FEJs F-18 when it hits the streets. But Skymaster is building a larger F-18 right now—will wait to see what’s up—can’t fly but one of these Bad Boys at a time—you know what I’m sayin’…

The ultimate for me for sure will be YA’s F-14, but Skymaster is building one also. There’s always something newer; better; prettier; you know what I’m sayin’—can’t have it all like Mike Denilin—he’s the Man [:'(]

As for the pipe, I’ll use what comes with it. And like you, I like insane verticals as well. And yes, landing a lighter plane is always a good thing in my opinion, but since different planes weight differently it’s really “mox nix� (don’t matter), just land that Bad Boy. Even the same plane built by its individual owner will weigh differently depending on the components you choose, building skills, etc—you know what I’m sayin’…

So for you: Wren or Falcon—kool beans with either one. One of my mottos that’s old as dirt but works for me—“it’s better to have and don’t need than to need and don’t have� [sm=drowning.gif]you know what I’m sayin’…

Mr DJ

PS. If anyone reading this disagrees with anything I’ve said—kool beans—I have no problems with that—just don’t attempt to beat [sm=punching.gif]me down for “my� opinion—thanks…

Hi All,
Just to throw more mystery on engine choices!!
I have a friend who flew an Skymaster F16 1/8th scale with an AMT Mercury (AMT180?? in USA??) which is just over 20Lbs of thrust and he said the vertical was not unlimited....When you are going vertical clearly All up weight is a major factor as well as thrust..and i'm afraid the 66 size turbine Falcon, Mercury,P80 all have more weight than the 54 size engines....a case of More power does not necessarily mean more performance....

brgds
dave

Sabastien,

Have you flown your F-16 yet? How'd it go?

Mine is ready to go. It's frustrating having to wait for all this white stuff to melt and the field to dry out before I can fly it.

Joe

HI TO ALL, ALTHOUGH I FLY FOR 22 YEARS IAM NEW TO JETS AND I HAVE JUST GOT A TRACK NUMBER FROM THE FEJ GUY,I ORDER AN F16 TIGER MEET COLOR ON THE 27-12-07 AND WAS SHIPPED 22-2-08, DELAY AS THEY SAID IS DUE TO 2 WEEKS HOLIDAY THEY HAD PLUS THE FACT THAT I HAVE ASKED THEM TO INSTALL EVERYTHING FOR $100 MORE. I WAS TOLD THAT IT IS A GOOD A/C FOR A FIRSTTIMER AND AFTER READING SOME OF YOUR COMMENTS I WOULD LIKE YOUR OPINION.I AM SURE I WILL REFER TO YOUR PREVIOUS THREADS WHEN I START WORKING ON IT!!

Thats interesting, I ordered my F-16 Tiger meet on the 26/Dec/07 and I havn't heard anything from them at all.
I too had the extra $100 installation.

Just received an email today that my Rafale has been shipped, hopefully I'll see it sometime next week!

Max,

You should send them an email asking for status of your order. In my case communication was excellent. I got confirmation at receipt of the order and when payment cleared. They gave me an estimated ship date, emailed me when it was shipped along with a tracking number, DHL emailed me when it was out for delivery, and Fly Eagle even sent me a follow up note after delivery asking if everything was OK. Any questions I had were responded to within 24 hours. From the postings in this thread others have had similar experiences.

Joe

Hi Max,
I too ordered my tigermeet F16 on the 26th of December too... And i have not got it yet either...maybe we should have got the gear doors added!!!

Brgds
Dave

Hey Joe/ Keith,

Did you cut the lips off the bypass?
How did you center the engine nozzle WRT the tail pipe? Visual only or did you measure it?
I am trying to leave ¾� gap between the turbine nozzle and the pipe. The measurement is without the bell mouth and to the inner wall. Is that how you set yours? I am using RAM 750F.

Regards,
Mike

Not sure what you mean by "lips".

First I centered the pipe by measuring it, then I visually centered the engine exhaust nozzle.

First install the bellmouth. Mount the pipe in the plane, find a block of wood 3/4" thick and put it up against the bellmouth; slide the engine back until it just touches the wood block. I don't know what the optimum gap is for a Ram750 and that pipe. I used 1" for my Wren.


A Ram 750 is a pretty heavy engine. Do everything you can to get it as far forward in the plane as you can. My Wren SS weighs a little over two pounds and I need about 24 oz. of batteries in the nose to balance it. I'm in the process of shifting the equipment tray forward and adding some more structure to the front in order to reduce the amount of nose weight and help support it.

Joe

They just emailed me out of the blue, they must keep an eye on this thread.
Exellent to know they are in touch with the jet community! they let me know they are planning to ship it next Monday.
Not that I was expecting it or anything as per the original delivery shedule of up to 45 working days.

Joe,

Thanks for the info, I was talking about the two mounting flaps/lips of the bypass. When the bypass is inserted in to the fuse the two flanges sort of sit on top of where the engine mounting bracket would sit on. I was wondering if you cut those off, I can't see leaving it under the engine mounting bracket.

So the gap is between the nozzle and the bellmouth, I always thought it was between the nozzel and the inner wall....I will have about 1/2" - 3/4" of the pipe sticking out beyond the tail......

Regards,

Mike

[sm=confused.gif] hi guys,

can somebody advice if a wren 54 autostart will be ok for the FEJ F16? I am a bit confused on these engine subjects as i dont have one yet and people talk about pounds of thrust and a/c weight. i see wren 54 is 14lbs is that ok? thanks

Me too Max!!! I got the same Monday shipping date.....

Hi Mike,

I'd call those ears and I cut them off on mine.

My tailpipe end is 1/2" inside the tailcone and I have a 1" gap. I also trimed a bit off of the inlets in the fuse so that I could move the bypass forward a little. Even with that I need a lot of nose weight to balance it. I'm sure your engine is longer and heavier than mine.

As I've said before; do everything you can to mount the engine as far forward as possible. I could move my bypass forward only about 1/4". If you trim the inlets you have to be careful that you still have clearance for the wheels in the retracted position.

Joe

Hi Mike yep i cut those lips off,it sounds to me that your engine needs to go futher forward,i agree with joe get it as far forward as you can regards Keith