Muffler for SH & Speed simulator

[swhailes]

My kit came with SuperTrap mufflers and some suggest I do not use them.
What mufflers are you using and do you have a source for them?

Additionally, the plans call for a speed simulator but I do not know what that looks like. Can someone describe it or have a picture?

Thanks.
Steve

[MichaelBurton]

555 timer info (http://www.kpsec.freeuk.com/555timer.htm)
The new kits came with mufflers from aircraft exhaust. I do not have the model number but they should be able to help you out. The speed simulator is a small black plastic box attached to the engine harness. It pulses at about 60hz I put a diagram for one on the forum somewhere. I built it and it is working for me.

[fiveboy]

But what does the speed simulator actually do? (Other than I assume simulate speed whatever that means).

Sometimes at night I sit so that the air conditioner blows on me. Is that a speed simulator?

[MichaelBurton]

It makes the computer think the car is moving. Without the speed simulator the engine will not be able to go above 4500rpm for more than 30 seconds. The engine will run normaly on the ground and you may even get into the air and then the motor will start reving up and down.

[PW_Plack]

Wouldn't a couple of magnets on the prop hub (or other moving part) and a sensor do the same thing?

[MichaelBurton]

I tried using the rpm output of the engine but it did not work. It caused the problem to happen sooner. I am not sure what the range is but 60hz works well. The 555 timer is cheap and easy to work with.

[rfi]

The correct terminology is SPEED SENSOR SIMULATOR. You can get one from Small Car on the west coast or I can sell you one for $50, or you can build one with a 555 timer counter chip. The output of the SPEED SENSOR is 5 volts, so you can use a 7405 regulator to power the 555 or do a level conversion circuit.
If you use the output of the tach sense line you have to divide it by two and convert it to a 5 volt pulse level to make it work properly. The tach line output is a 12 volt pulse.

[swhailes]

Any thoughts on using the MagnaFlow 14444 Muffler 2 in. Inlet/2 in. Outlet on a SparrowHawk?

Steve

[Hoges]

I'm in the process of making a new exhaust system for my SH. It has an EJ25 engine and I'm not too keen to put the muffler across under the engine as it will add some heat to the radiator but it would be very neat and totally suspended off the engine which I like.
Anyone else have mufflers under their engine or photos of exhausts on SH's?
Steve, do you have any photos of the Magnaflow exhaust you mentioned?
Scott
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[Steve McGowan]

Any muffler shop can do this for less than 200.00.

This is all off the shelf standard auto muffler and pipes, nothing fancy about any of it.. and I also plugged the EGT ports and cut the wires off. You will need to cut the down header pipes at the Knuckle joint then swivel them to the verticle position, then reweld them.

The 3rd pic is what was on my SH and I also had to remove the oil cooler. Not being in Arizona and the constant heat it's not needed in Georgia.



Be sure to wrap the area with heat resistant asbestos tape to keep the battery and radiator from getting hot from the exhaust.

You won't believe the difference.. on the ground at idle, "REALY NICE"

In the Air,, "UH" it's the prop makin the noise anyway..

Steve McGowan

[swhailes]

Here is a picture of the magnaflow 14444

http://www.magnaflow.com/02product/displayapplications.asp?partnumber=14444

[Hoges]

Thanks Steve & Steve,
In regard to oil coolers, I have been asking a few guys who fly EJ25 powered gyros in central Australia (not SHs) and they say they are not needing an oil cooler. What's the experience in hot parts of the US?
Scott
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[lanichol]

I spoke to aircraft exhaust (http://www.aircraftexhaust.net/oem_lsa.html) yesterday and they have a few new ideas on an exhaust system that will cut down the noise. The Sparrowhawk design from AE was known to be loud as we all know. They have mufflers different than the ones supplied with the Sparrowhawk that has 6 noise damping chambers with only a slight increase in back pressure.

Aircraft Exhaust suggested exhaust would be similar to the rotax with one exit to a tail piple that drops along the keel. The longer the tail pipe, the less noise. Very similar to the original RAF exhaust which was fairly quit. The RAF just did not last long.

My goals is for a stealth gyro where you hear mostly the blades, not the prop and engine. People get a little crazy around here when it come to deer and land ownership. I would hate to be accused of scaring the deer or causing them to move across property lines.

[Steve McGowan]

As I have posted,, it's not alway's the exhaust.. The warp drive props have lso been banned on airboats in Fla. in certain areas..

What you see in the pics I've posted.. If your not careful you'll walk into the prop because it's so quiet on the ground.. Once the engine starts hitting 3500 RPM the prop starts making the noise..

The super traps,, In My Opinion and thats all it is.. were not a good selestion for an auto engine, neither is the straight tube pipes with the cones in them that followed with the 2&3 SH's

It's an AUTOMOTIVE engine,, Thats all, and until we get about 2000' or put a 12" cord two blade prop on this thing.. It's gonna stay loud to those on the ground.

Many Hours of testing was done at Buckeye when I was there with GBA.
From Props, to Exhaust.. everything was considered and tested with a DB meter.

Again,,, I"m NOT an engineer,, Just workin from experience..

[Steve McGowan]

Thanks Steve & Steve,
In regard to oil coolers, I have been asking a few guys who fly EJ25 powered gyros in central Australia (not SHs) and they say they are not needing an oil cooler. What's the experience in hot parts of the US?
Scott


When I was there in Australia in 05 with Greg Williams it was 112' on New Years Day of 06 on the beach at Bombadary..
Then we took Gregs SH up to Woolongong to do the test flying and we didn't have any temp problems that I remember..Only problem we had was with the locals and the counsil complaining about the noise and wanting me to fly out 2 miles over the bay on the down wind.

Needless to say,, That didn't set right with me and a newly built gyro.
In Aizona it seemed to help keeping the oil temps down with the cooler.

Again that was temps of 100 plus and many times as much as 115 on certain days..But I was the only test dummy out doin much at all after around 11am or so when it came to flying..

[lanichol]

What you see in the pics I've posted.. If your not careful you'll walk into the prop because it's so quiet on the ground.. Once the engine starts hitting 3500 RPM the prop starts making the noise

There was a post on shaping the tips of the warp blades which seemed interesting. If you go to the warp drive page they tell you the RPMs the prop starts making noise. And I remember a post where the were a few RAFs with a different gear ratio had alot less noise. The HP curve is fairly flat on the Sub. It would seem we could turn a few less RPM with a different gear reduction and still be in the Sub power band to help keep the noise down and better fuel economy. Maybe higher compression pistons with premium fuel.

I am no expert, but it seems we just don't have the Sub dialed in. If all you have is prop noise then your configuration for the exhaust has solved the engine noise.

[route66]

I remember watching a few of the noise tests in Buckeye. One day they were testing a Prince P tipped 2 blade which sounded like an improvement to my untrained ears with a lower tone sounding more like a Cessna. What I perceived as a more tolerable sound was just a perception when challenged with a DB meter. Seems the P tipped prop had similar DB readings to the Warp and Ivo and they were experiencing some vibrations from the 2 blade setup, but did have a lower tone.

[MichaelBurton]

I did some of the testing on the Prince prop. I liked it in flight but there was a problem with a harmonic vibration. The DB numbers were similar but the tone was much lower. This is good as the lower tones are less irritating. In the end we could not use the prop due to the vibration problem. This is when we sent the prop to Buckeye for further testing. Some were convinced that they could balance the vibration out of the prop. Having flown the prop I had decided that that would not work as it was the vibration happened in pulses. In the end my convictions were confirmed.

[JimGyro]

Hi Steve
Here is a picture of the speed simulator for the Sparrowhawk II. It should be the same for your kit. Hope this helps.

Jim