MarkShapiro

My Feedback: (52)

I am being told that the gap between the end of the tubine nozzle and the entrance of the bellmouth is ideally 1 and 1/2 inch, but not less than 1 and 1/4 inch for my Rhino. Thoughts?

joeflyer

My Feedback: (48)

That's what Jet Central recommends. See http://www.rcuniverse.com/forum/m_6830142/tm.htm

BluFox

My Feedback: (10)

Mark:

We discussed this on the telephone. For review and clarity, allow me to again explain our recommended requirements.

Extensive testing with all of our turbines matched to the respective pipe sizes (diameter) was performed to determine:

1. thrust loss / gain
2. heat transferred to the pipe
3. temperature of the turbine at idle, half and full throttle.

You have a Rhino. . .which produces in excess of 36lb of thrust. Our test concluded the following:

1. If the nozzle of the turbine is 1/2 inch or less, SOME pipes (manufacturer differs) may colapse blocking the exit of hot gasses diverting them back to the airframe. We have spoken with several customers who reported a fire while flying and resultant crash. The pipe / turbine nozzle position was the culprit. This spells disaster. Loss of 2 + pounds of thrust and increased operating temperatures of the turbine.

2. We determined the absolute perfect position is 1.5 inches from the outer nozzle to the entrance of the METAL pipe bellmouth. This proved reduced operating temperatures of the turbine, pipe and fuselage structure. The pipe we tested (COMP -ARF Ultra Lightning stock pipe) was of a low enough temp to put your hand on the outer skin of the pipe.

3. Further, with nozzle and pipe relationship between 1 and 1.25 inches thrust loss was just over 1lb with recorded temps about the same.

We realize every installation is different however most manufacturers of jet models allow for such installations. Some installations require the intake ducting where starter motor of turbine meets, to be shaved to allow the turbine to be moved forward further into the duct work.

We published the measurements both maximum and minimum on our web site to be used for reference with our customers when they are planning their install.

Thank you for your question and continued success with your Rhino.

Eric Clapp

acw

My Feedback: (1)

Hi Eric,

What would be the ideal range for a Rabbit. Is it like the super bee Minimum 20mm (3/4" / maximum 25mm (1"))

Thanks

Arnaud

BluFox

My Feedback: (10)

Arnaud:

Thanks for your question as we have many, many Rabbit owners who may read this.

Your answer:

1. Pipe diameter is a maximum of 75 mm with a minimum of 60 mm
2. Maximum distance from nozzle to pipe is 25mm
3. Minimum distance from nozzle to pipe is 20mm

If you have any questions with your install, please let me know via email or through this forum.

Best regards,
Eric

f106jax

My Feedback: (16)

Hi Eric,

Is the 1.5" distance still optimal when using a bi-furcated duct as in my Skymaster F-4? I'm using the bottom half of a bypass and the distance from the end of the tailcone to the start of the metal exhaust tube is only .5". All seems well, however I have noticed other Skymaster F-4/Rhinos that are using the bellmouth seem to have much better acceleration than mine.

Just trying to decide if it will be worth my while to get rid of the half bypass and install the bellmouth for better performance.

Thanks and Happy New Year!

Mike

MarkShapiro

My Feedback: (52)

Thanks again Eric. I have my Rhino set up in a Eurofighter and I managed to obtain exactly the 1-1/2" air gap that you recommend. Thanks also for the detailed explanation. I was still a little unclear on the details after our conversation.

BluFox

My Feedback: (10)

Hello Mike:

Happy New Year to you and Cindy !

Actually, the distance from the nozzle to the entrance of the metal bellmouth of the pipe is more critical than the bypass.
This distance is obtainable in the F-4 install. You will see a pronounced improvement if you reposition your turbine.

Tests have also shown, when installing the bypass, use only 1/2 (bottom) and leave the cover off. The turbine actually breathes better (gets more air) runs cooler and cools down faster. The excess air coming from the fuselage helps with the pressure area at the nossle/pipe area. The negative is, if you should experience a hot start, with the bypass cover removed, you must be quick with the fire extinguisher.

Try it. . .you will like it.

Cheers,
Eric

f106jax

My Feedback: (16)

Hi Eric,

I've already ground the joiner flange on the intakes and have the starter cone all but touching the intake. I don't believe that I can go any farther forward with the turbine. If I move the exhaust towards the back I will be able to achieve the 1.5" spacing. The tube will be outside of the rear of the bypass but I'll be able to install the bellmouth then. What do you think of that idea?

I've only been using the bottom half of the bypass.

Mike

BluFox

My Feedback: (10)

Mike:

Just so I am clear with your request, can you post a picture or two?

Thanks,
Eric

f106jax

My Feedback: (16)

Hi Eric,

I've attached a photo that shows the intake area, showing that the starter can't go any further forward. Another photo looking into the rear of the bypass showing the turbine tailcone's position in the bypass. The other photos show the position of the exhaust duct fitting into the bypass.

Would I get better performance by moving the exhaust duct rearward and installing the bellmouth? I'd be able to get the 1.5" of space from the bellmouth to the tailcone but the exhaust duct would then be outside of the bypass. Not a big deal if I get better performance, I can always remove the bypass or just have a gap between the end of the bypass and the bellmouth. Right now I have apx. .5" between the end of the tailcone and where the end of the bypass/start of the exhaust duct.

Thanks very much,
Mike

BluFox

My Feedback: (10)

Mike:

Position of the turbine is what looks to be as far forward as possible. I cannot tell from the carbon fiber partial cover at the rear of the turbine as to the position of the nozzle/pipe. Do the best you can to optimize the 1.5 (minimum 1.25) distance between the metal bellmouth entrance to the pipe and the nozzle of the turbine.. What you are striving for is the distance between the nozzle (outer) of the Rhino and the entrance (metal) to the turbine pipe. Centered of course. Install other wise looks great.

Cheers,
Eric

f106jax

My Feedback: (16)

Eric,

Thanks for the info and advice. However, in light of the predicted frigid temps this week, I think that I should bring the F-4 to your shop for you to look at it personally. This might be a project that lasts well into April.

Thanks again!
Mike

MarkShapiro

My Feedback: (52)

"What you are striving for is the distance between the nozzle (outer) of the Rhino and the entrance (metal) to the turbine pipe."

Eric,
Just to be sure, when you say "the entrance (metal) to the turbine pipe," I assume this means the actual entrance of the bellmouth and not the entrance of the pipe were the bellmouth left off of the pipe. Am I correct? I'd send a picture of my set-up, but my camera has been loaned out until next week. Thanks.

BluFox

My Feedback: (10)

Measure from the edge of the outer nozzle of the Rhino to the beginning entrance (edge) of the metal pipe (turbine pipe) installed in your jet. Distance should be 1.5 inches optimal and 1.25 inches minimal.

Metal bellmouth is that part of the turbine exhaust pipe which inserts into the body of the pipe and is secured by two / three screws.

Regards,
Eric

MarkShapiro

My Feedback: (52)

Alright Eric. I think I have it now, but just to be sure, the pic is how I will have the turbine situated to the pipe. It is exactly 1.5 inches between the end of the nozzle and the opening to the bellmouth. Does this get your blessing? Thanks again.

BluFox

My Feedback: (10)

Mark:

Congratulations. . .you just won a pull from the Jet Central draw bag of goodies !

Yes, this is exactly what you are looking for. If internal installation, I suggest you get a pint of BVM heat shield product. I use a 3 or 4 inch roller to apply. Two coats will do it on the fuselage area between the back of the turbine case to the entrance of the pipe. Caution to application as this product can build weight quickly.
For complete bypass applications, this still remains the "target distance" between nozzle and pipe entrance.

Call me with any questions.

Regards,
Eric

MarkShapiro

My Feedback: (52)

You're the best, Eric. Thanks. Already painted two coats of heat sheild but probably over did it. Covered entire rear fuselage area, top to bottom. Also included heat blanket last night. Anal retentive? Perhaps. Thanks again.

RC Larry-RCU

My Feedback: (1)

This is GREAT info. Only wish I had read it long ago! This also answers a big question several of my buddies and I had. Installed a new TAMS pipe, only to have the outer pipe start collapsing a bit. First pipe REALLY gave way! Luckily no fire. Installed second pipe and outer pipe started to do the same but not nearly as bad. Has not collapsed any further with several flights. In other words,,,,,,,,, I'VE BEEN LUCKY!!!! Gap from nozzle to pipe inlet is approx 1/2". This was recommended to me by the vendor I purchased it from. Set up is a Rhino installed in a Euro Sport. As soon as I get up from this keyboard, Im headed out to the shop to re-position my pipe. Id love to find out I was 2 lbs short on thrust! Really dont need it as my Rhino really hauls the Euro now, but it will be so much nicer knowing I may be elliminating the hot temps causing the pipe issues. Already has blanket and heat paint, so this will be a quick fix.

Thanks for the info Eric

f106jax

My Feedback: (16)

Hi Larry,

Initially, I had 1/2" between the exhaust cone and the tailpipe and then increased the distance to 1.5". There was a noticeable increase in takeoff acceleration on the F-4. The pipe has also been much cooler, only being hot to the touch in the area of the Y.

Looking forward to catching up with you this summer!

RC Larry-RCU

My Feedback: (1)

Thats Great Mike. I really love that F-4 of yours. Great scheme!!! Ive been looking at the Jolly Roger scheme a lot. LOVE that plane! Like I was saying, my Euro certainly has no power issues now, but I'd be more than happy to add a couple more lbs of power should that happen. I just want to assure myself the pipe isnt going to collaps! When we were packing up to leave your event last year, Joe happened to look into my tail pipe when I put in on the top shelf. He said I REALLY needed to look close at it. Inner pipe was looking BAD! I was very lucky.
Robert, Joe and myself are really looking forward to burning some fuel with you guys again soon. We have a few more jet junkies in our ranks now, and we'll certainly have them in the convoy when we head to PA this summer. I guess youve heard the Mid Atlantic Jet Rally has been scraped this year! Really sad. We were hoping to get you and Cindy down here for that one. A few of us are working on getting a meet going here in NC. Hope to have more word in a couple of weeks. So many jet guys around here now, yet NO MEET!!!

RC Larry-RCU

My Feedback: (1)

Follow Up on pipe relocation.
MUCH MUCH cooler runnings!
I'm set at 1 1/2" now, and it was a very noticeable difference. Fuse use to build up a lot of heat up on top side. Now it stays cool as a cucumber! Also, pipe shows no signs of colopsing, even after I popped the wrinkles out from previous runs.

Test flew plane today. HOLY ^$#%$#!!!! Very noticable difefrence on power!!! Not sure about top end speed, but vertical performance was no doubt better than ever! Also noticed quicker acceleration on take offs. Addition of ceramic plug and moving tail pipe to correct position has made this Euro a whole new plane.