Is there any chance that a bobbin style 8/32 vibration mount would do the trick? Google Anti vibration mount and see what you think..
Thanks,
RC

No, and in fact my guess is that it would be particularly bad when combined with a standoff-style mounting system. When you think about the forces on the standoffs, it seems there would be a tremendous amount of stress on the engine mounting tabs and on the engine mounting bolts.

The [link=http://www.rcuniverse.com/forum/m_6285026/anchors_6285026/mpage_1/key_/anchor/tm.htm#6285026]Hyde-style soft isolator mount[/link] is the best (only?) way to go, and they aren't all that hard to make once you undertand the process and [link=http://www.rcuniverse.com/forum/fb.asp?m=9692415]how the concept works[/link].

I was a bit dubious at first about how well the mount would work and about my ability to make one, but it turned out to be easier than I thought, and it is working fabulously well. I will be making another one in the next few months if I am able to find a second-hand plane to go with my #2 SAP-180.

I am glad that you said something. I have some on the bench ready to be mounted. Your comment makes absolute sense thou. The ring on the hyde style mount locks that sort of movement out. Dave Brown sells a similar style mounting system. It is mounted to the engine backplate and with out stand offs.

Thinking out load now...
If the motor was mounted to a ring similar to the your hyde mounts then the sandwich mount between and to the firewall that would eliminate the translational stresses that the motor standoffs would be subject to. Just a thought.
I know, "just make the hyde mount already" ggeeesh.
Again thanks for saying something.

Some current thrust measurements:

[youtube]http://www.youtube.com/watch?v=iRM8_KY43_s[/youtube]

Wow! 22 lbs!! Perfect for a 3D setup - should yank a 12 lb plane out of a hover with no problem!

I measured my pattern combination with a simple spring scale (fish scale... not too accurate[&o]) and it pulls a bit under 15 lbs, but with much greater pitch speed (with the 15.5x12W) and much quieter.

Exactly!

Once you've made your first one, you won't hesitate to make them in the future.

Most of that is air frame noise.  I have the same bird and the thing is loud.  I am working on quieting a few things down.  Most of that noise is from the ball links on those big barn doors of ailerons.

I have soft mounted the SAP 180 in the EFXtra as shown in the thread for that plane. I believe I posted a bunch of photos on that. Much quieter set-up. Expect 3-6 dB delta on noise

But it is still louder than the Temptress (which is extremely quiet by gas standards!), no?

Do you think the increased noise with the Extra is due to the more voluminous fuse and cowl (and wings, perhaps) and the open structure design? All else being equal - with the engine, mount and exhaust - what else could it be?

Actually, no that much!! Temptress and Extra equipped with same prop compare favorably to one another. Extra's advantage is that the pipe is fully enclosed, surrounded with dead balsa. Extra's disadvantage is wood and film resonance. Overall, noise is about a wash between the two airframes in the air.

Temptress is about as quiet with the SAP as with the Webra 160 after considerable work to get her there....not quite but very close. A fully enclosed tunnel with dead foam lining would quiet the set-up even more,,, but the same would be true of a glow set-up. What we are fighting is the considerable increase in exhaust temp compared to glow. Hot reports are louder than cooler reports.

If we want more quiet, we need to cool the pipe (exhaust gas) more effectively. That's not a trivial thing.....a much closer fitting shroud surrounding the pipe would help but adds weight. Can't really make it out of depron because it would eventually melt from the gasoline. Glass is heavy and so is carbon...and expensive. Soft balsa would help but also adds weight. Soft balsa shroud is probably the best bet.

On the other hand, I have a pretty quiet set-up already so I am not inclined to investigate much further. If something makes sense in the process of assembly then I will incorporate it.

The set-up shown in the video is very loud compared to pattern set-ups but that's a requirement for the type of flying it is intended for. It's a show plane....spectators are attracted to loud.

I think the camera microphone made it sound horrible and loud....louder than in person by quite a bit.
Also, the exhaust is being thrown right down on the asphalt...so that probably does not help at all...
I have quite a bit of air going through the tunnel...should help. It sounds quiet in the air...much quieter than on the ground.

Todd,

I guess that was a rather unfair impression of the sound since the video was made directly behind the plane at full throttle!

Have you installed or do you plan to install smoke?

A simple crankcase pressure system with a couple of check valves would be extremely lightweight. I did this with a .46-sized Decathlon (with a .61, of course) and the total dry weight was 5 oz.

That sounds interesting and I have thought about it before!!

Got some air time in this morning. I only have a 18x6 and a 18x10 and I definitely preferred the 18x10 for my flying style. I am practicing to enter my first IMAC competition. I will need to go back and read your information about props.

Crazy power with the 18x6 thou... up lines... not a problem. Thats definitely the 3d prop.

With the 18x10 it wasn't pulling over the top well, up lines were weak.


Smoke?... I'm in.

I can't comment on the 3D props, but suffice to say that the IMAC precision flying sequences have a lot of similarities with pattern. With the Extra being a somewhat draggy airframe, perhaps an 18x8 or 17x10 for IMAC precision (??).

I was able to add another prop to the list I've tried - the APC 17x12N (narrow) pattern prop - and, as I have said about some other props, it isn't horrible but it in no way matches the brilliant performance of the 15.5x12W with my [link=http://www.rcuniverse.com/forum/fb.asp?m=9732410]SAP-180 cookbook[/link] set-up.

18x8 would probably be nice if the noise was reasonable.

If you haven't seen Todd's Extra fly... I posted these on the other thread... this may be redundant:


[youtube]http://www.youtube.com/watch?v=GZjNyixe0sw[/youtube]


[youtube]http://www.youtube.com/watch?v=FrokdPQ5kh4[/youtube]

I have run a 19x8 and 19x10 hybrid prop. Both allow the engine to spool up to its sweet zone. However the plane was not only loud, it wouldn't go anywhere....much too slow for pattern.

Both props would be good sport and 3D props

Which prop were you using for 22 lbs of thrust?

I've been to that flying site and it extremely nice. By far the best one I've been to since moving to the NE 5 years ago. I would love to hold a Pattern Contest there if the club would allow a weekend for the Pattern Fliers. Even a 1 day contest would work.

Last weekend we were at Coningham PA, which is a club that has no pattern fliers in their midst. Yet they held a Pattern Meet. Pattern contenstants generally run the administative work so the club only needs to provide helpers for the concessions stand and impound. Don't even need a Contest Director...many of us are CDs so it's no big deal. The entry fee was 35$ so the club coffers were padded with about 500$ plus the income from the concession stand. It's one way for a club to add some income

Ran the 18x10 some more today and 4-5 minutes into the my second flight I lost the top end.   Landed and the motor had tightened up pretty bad and it didn't sound very good turning it over.   Went back to the 18x6 after a long cooling period and it was certainly much happier with that prop.  I have the 15.5 on order.   What the heck happened... I am thinking I got it way too hot.   It wasn't air flow. 

I would guess that you are running the engine too lean. It needs the high speed needle opened to 2 -2/14 turns if you are running a piped set-up as I have described here-in. Not sure what plane you are using....it must have a lot of cooling both inlet and even more outlet. If you are flying the EF Extra, baffling could help

Here's where I was when my engines were new[link=http://www.rcuniverse.com/forum/fb.asp?m=9536834]MattK's early needles[/link]

The needles now after pretty close to full break in are HS 2 1/8 open and LS 1 1/8. Pipe is at 28" to baflle straightline from the spark plug center. Running 90 octane at 50:1 BelRay MC-1 synthetic motorcycle oil. The prop is a 17x12 std blade but a variety of props will run at these settings. I tried the prop Bob Moulder lent me (15.5x 12W) and also Dave's 15.75 x 11, 3 blade. These all work okay on the set-up. The 18.1x10 apc is a good choice for break in and if you don't mind a little noise, will work very well on pattern planes.

The 18x10 should be less load than all of these props.

I should be just above 8000 with the Xoar 18x10 on a pipe. Is that correct?

I have not run an XOAR 18x10 standard woodie. I've only played with XOAR electric woodies modified as I've described before.

8K is probably low based on the experiments with the 18.1x10 apc. Except it's much warmer and more humid than when we getting out numbers in early spring so 8K is possibly in line, but I don't know. I've not run that specific prop

The Xoar 18x10 was one of the props I tested. I didn't tach it, but I did one flight with it and it was clear that it was not adequate for a 10.5-lb pattern plane, and almost assuredly not for a 12-lb IMAC model. I haven't actually used it on an IMAC-type model, but I've seen enough to bet the farm that it wouldn't work out. I tached a couple of the APC 18x10's and they consistently turned about 8200 rpm. All the flavors of APC 18x10 that I tried (pattern, sport, old-style pattern) pulled the plane pretty well but were noisy and just didn't have quite enough pitch speed for pattern.

This engine likes the revs! Find a prop that permits over 9000 rpm and you will be happy. Even for pattern, my engine is quite happy with the 15.5x12W turning 9200 rpm.

This is why I think you might end up with an 18x8 (at most! - maybe even a 17x8!!) for IMAC precision, or whatever prop Todd was using in the recent video that produced 22 lbs of thrust![sm=thumbup.gif][sm=thumbup.gif]