Question on exhaust pipe angle

MMorgan

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Since I fly off of grass all the time here at my house, I have noticed all the burnt spots where I takeoff and land.

I am a little worried about starting a fire especially if I land somewhere in some taller grass.

I am attaching some pics of my pipe in relation to the frame....can some of you guys tell me if it looks like it is pointed too far down?? I can make a heat shield to cover the wires which I would have to do if I turned it up any more.

Also....there are no wires on the other side....can it be turned to the left side of the ship or is there some reason it has to point to the right side??
 

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hillberg

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Right side exhaust is to remove translating tendicy, Done first with the Rotor Mouse, Jet Exec & now the Helicycle.
It reduces pilot work load, As t/r thrust changes with torque the tendicy is automaticly adjusted by exhaust thrust with power changes.
 

StanFoster

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Mike- Your exhaust is pointed down way too much. Mine just misses my longeron frame tube. I placed an aluminum shield to keep the exhaust from scorching my powder coating. The exhaust will leave an elliptical patch of browning grass the next day, but it wont start a fire.

As Don stated,..a right thrust helps offset translating tendency.

Hover autos are noticeably easy to do as less right cyclic is needed when the power is cut.



Stan
 
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MMorgan

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Thanks Stan, kinda figured it was but wanted to make sure. I was over visiting Jim and Clarence a couple of weeks ago but forgot to look at their's.

My tail rotor control cable as well as radio coax passes right there so i will have to make sure my heat shield works well.

Thanks again
 

StanFoster

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Mike- I just took these pictures. You can see my sacrificial heat shield. Those nylon zipties never have softened. My teleflex cable was my main reason fo doing this....and keeping my white powder coated longeron......white! The frame stays clean and I never wipe off the heat shield.

The third picture shows a tape measure....1.5 inches in case you cant read it from the bottom of the longeron to the chrome pipe.


The last picture is looking inside my exhaust pipe and you can see the EGT probe which you will have to drill a new hole for.....




Stan
 

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MMorgan

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Thanks Stan, your exhaust pipe is noticeably longer than mine.

This afternoon I turned it up some and made a heat shield....and yes I had to redrill the EGT hole.

Photos attached showing the changes. I will test fly maybe tomorrow and make sure its not getting anything hot on the longeron like the tele flex cable as you noted. There is a small piece of white fire shield over the cable in that area also.

I was worried about the fire danger in the grass........a few years ago a friend of mine lost a Hughes 269 when it burned slap ass up from catching the grass on fire after a landing.
 

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hillberg

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Those tie wraps need changed to adel clamps on the front of your ground plain, Hughes list a test 530 to a grass fire on a landing in tall grass,
 

MMorgan

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Thanks Don....I'll change them today
 

StanFoster

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By the way. my heat shield is bolted on ....the zip ties are just indicators of how hot that shield gets. My Teleflex cable is on the outside of it. So, far....no signs of high heat except the white kryon paint has slowly turned brown.....but the underside turned black the first couple of flights.

Everything is cool to the touch except the shield which just gets warm.


My elbow is 90 degree elbow, but the exhaust cuts the corner a little...and I would say the thrust is about 20 degrees rearward. That is from feeling the exhaust blast and some overhead shots that show the exhaust plume headed back a little.

When its sitting on the ground....and the throttle is revved from idle to full rpm.....you can feel the helicopters tailboom move to the left.

Blake told me that there is 30-35 pounds of exhaust thrust coming out.


Stan
 

hillberg

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We did an exhaust plume test, flight idle no load at the exhaust temp probe 777 degf same temp, 3" aft of probe 670 deg f 9" down 450 deg f at the exhaust pipe opening 370 f deg 6" beyond 330 deg f the temps drop off quickly , Powered up the same ratios apply. A good wenie roaster.
 

500e

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For fires try a 500 on low skids, you can see where we land on high skids by brown grass
 

Mylo

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hill,

Maybe a little confusing, here's some clarification on what I'm asking.

Mike was correcting the 'angle' of his exhaust pipe so that it didn't burn the ground as much, in effect, blowing more exhaust gases out to the right as opposed to down. Stan commented on how there is significant exhaust thrust (30-35 lb) to create a noticable effect on the ground when he increases RPM from idle to full.

...I was wondering if Mike could feel something different in the handling in the air as a result of this new thrust out to the side.

Mylo
 
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MMorgan

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Mylo, I flew today a couple of times and no difference.....I did not expect any changes as you described since it was only a few degrees difference in the angle from old to new.

I did see a BIG difference in the "burning of the grass" as the picture shows.

The large brown spot is where I landed and sat a minute or two on Monday.
Today I landed on the brown spot and sat there a minute or two. As you can see there is no "scorching " whatsoever in the grass above the brown spot in the picture (which was the direction the exhaust was pointing)
 

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StanFoster

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Mike- You will see the grass turn brown in a day. It doesn't heat it enough to but not, but kills it instead over a day or 2.

Stan
 
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