MTK

In this thread, I will be posting progress on the soft mount I am building for this engine. It may be of some interest to some Pattern folks who might have an interest in this engine. It is a bit heavy by Pattern standards but I am estimating that I can build my new design under the weight limit. Regardless, the new design is fairly large by current standards so it will be able to absord the extra weight with no effort

Matt

MTK

The first photo shows the loosely assembled set of cross grained balsa rings that will form the spacer section of the mount. Not glued yet
The second photo shows the individual rings with a ruler for scale and the third, the spacer plus the front and back 1/8" aircraft ply discs

MattK

MTK

Some more progress

MattK

MTK

And a bit more. The idea is to assemble the whole thing, then remove the unecessary portions

Mattk

bla bla

Over here, the pattern community has been making their own Hyde mounts ever since Mr Hyde sketched out the idea at the WC's years ago and gave it to one of the Norwegians! And even though they're home made they work perfectly... just like a Hyde. Which isn't surprizing.
Good luck with your project.
Keep us informed how you intend to solve the nose ring situation.

As you'll be aware, it isn't the back part of the a decent soft mount thats thats been posing the problems for petrol pattern.
It's the front... the nose ring. The magnetic pick up gets in the way.
The only way around it is to drop the nose ring and use a stiff, soft mount....that kinda defeats the point.
Keep posting the progress.

rmh

If you want a setup which will support and allow rotation - make a second rotating ring at nose of model and suspend the engine between the two - I did this years ago working on YS emgines
The forward ring was attached to fuselage via four angled, tubular pieces of carbon fibre
the whole contraption worked very well but a pain to build
I made my own Rotomount for years -did same thing as the expensive mounts -

MTK

Dick,

Did you play at all with the front webs? I read on your thread that you have yours hard mounted so there would be little use to drill and tap the front webs. I am planning to use the area for some angle stock and rubber snubber to lock the nose softly. That is one approach to a solution for the nose ring.....

A more elegant solution could be built in at the factory: the front bearing housing could be made oversized such that a slot could be milled for the sensor to slide into. The outside diameter would serve the function of nose ring mount just fine without interfering with the sensor. Meat could be removed from the extra diameter to lighten, just like they did for the prop drive washer. This area then would be similar to a glow front bearing area for inserting the nose ring. An aluminum ring could be machined and fitted to the front bearing housing and could do the same thing, but is less elegant....

If the pattern community showed enough interest in using this engine, then the factory might be persuaded to do something about the nose ring installation. That's a very big IF

MattK

rmh

No - having been though the soft mount thing many times (too many) I decided that the best bet for the engine was a wooden fuselage and a absolutely twist/vibe free dead solid, mount to wing tube attachment and rigid aft fuselage . This setup is called mas balancing - trying to make the entire model damp any movement. The ZDZ ignition really does soften the blows on this engine . different than glow ignition
very different.
The glass models are like violins - they will amplify any noise . but they also can have a cradle built in which is rotating at front and rear of engine
personally I don't care for the all glass stuff - way too much money and the "fixed" nature of them puts me off.

MTK

Yes, it's a good way around the issue, I agree. Balsa is still the "deadest" of the current engineered construction materials and mass distribution can be facilitated. But can be heavier than desired if not supremely careful. My new design's fuse is mostly glass/foam sandwich but I have added balsa from the nose to the wing tube and locked it with formers.

I came up with third, different approach to nose ring fabrication/attachment. I'll post pics when I finish it and have run it.

MattK

MTK

More photos of assembly

MTK

About 2 photos at a time is all it's allowing me to do. Too high a rez I guess

MTK

Assembly

MTK

Hmmm wonder what happened to the last set of snaps

MTK

more assembly

MTK

Construction is 1/8" aircraft ply, 1/16" aircraft ply, 3/32" cross grained balsa epoxied with 2 oz glass cloth between the layers

Rubber stock is from inner tube of a lawn tractor wheel purchased at local ACE Hardware. Cuts easily with razor knife.

Note that rubber must be thoroughly cleaned with rubbing alcohol to remove any soap the manufacturer used to release the part from the mold. When this is done correctly, the rubber will adhere with regular CA glue to rubber tearing strength.

Note the weight of the nearly finished mount is about 3 ozs....quite acceptable for this size engine

MattK

nonstoprc

My Feedback: (90)

Interesting. Please let us know how it works under the ZDZ.

I hard-mount mine with a set of alum standoffs. Vibrations around 3500 RPM are quite noticeable. Beyond that point, the engine runs very smooth.

RCDennis

Matt,
Glad to see you doing the experimentation on the nose ring. As I have told you I have this motor in a Symphony and a Hyde mount made by Merle for this engine. He says it is constructed so as to not need a nose ring. One of the problems after I took delivery was that the mixture control screws ended up inside the mount, so I had to use short standoffs to get access. Some day if work allows I will get the chance to run the engine in the airframe and maybe even fly it. This will be the true judge of the need for a nose ring.

Dennis Cone

MTK

Dennis,

I should have the whole thing ready and running by next weekend. I will take the final snaps and post here. I intend to adapt the nose ring to the bench mount to get a full flavor of the whole assembly in actual use.

So far weight is in line with expectation. The model will likely come in at 5 kilos tho. I am using about 1140 squares of wing so weight will not be a problem

BTW what was the weight of the hyde?

MattK

MarkGrabowski

Matt, did you place some sort of slippery material between the two rings (like monokote or teflon) to keep them from turning into sawdust?

MTK

Mark,

I have built these mounts for engines as large as 2.2 in the past with no additional material between the rings....only fuel proofing (epoxy coating). The engine in general will pull the rubber enough even at low-mid power settings, eliminating contact at the ring interface. The rings are capped with 1/64" aircraft ply regardless so this is not a big deal. I have the original mount I built about 5 years ago still in use today for my Webra 160, some 1700 runs later. One of these years I will disassemble the thing and take a look. Merle Hyde gives a 3000 run warranty on his mounts with good reason.

At idle, the engine bounces enough to make the rings slap one another and you can hear the slapping of the surfaces. Actual experience notwithstanding, I felt that couldn't a good thing so I started lining the face of the backplate ring with thin rubber stock from a bicycle inner tube. This is adhered the same way as the rest of the rubber.....cleaned with rubbing alcohol and ca'd in place. It's a simple add-on during assembly and is only added to areas between the bolt holes.

I am sure the slapping of the rings is still happening except the potential effect is eliminated and noise gone..... always a good thing on a pattern model. I do not recommend that a harder substance like monokote or even teflon be added. They are slipperier than rubber for sure but are also much harder and don't absorb any vibration. I'll post some photos of that later this week.

MattK

nonstoprc

My Feedback: (90)

Matt,

Looks like the rings are glued to the firewall side cap only as otherwise the vibration will not be damped. Right? The rubber is the key to damp the vibrations. You mentioned the inner tube of a lawn tractor wheel. How thick is the rubber material? Does the rubber glue to the rings? If so, at each layer or just to the outside of the rings?

Thx

MTK

Nonstoprc,

rubber stock is approximately 1 mm thick and is approx 3/4" less in diameter than the ring is. It is stretched to fit. I'll show photos of assembly when I get to it. I've gotten sidetracked and the project has come to a screeching halt. Started to build the wings and stab of my latest design...Deja Voo, Deja Vu', or Deja VooDoo. Haven't decided which name yet

CA is medium stock and is applied to the corner between the ply plates and the balsa rings. The rubber edge and very little of the rubber side get glued. That's the first layer at least. The second layer is layed over the edges of the ply plates and glued to the ply edges only. I think photos will make this self explanatory

MattK

aerobear

My Feedback: (4)

Has anyone tried this?

http://escomposites.com/soft_mount.htm

I have not seen it running but Ed has something similar on his Alien
with the ZDZ RE and says it works well.

Cheap, light, simple, no large excursions to break your header.

Each wellnut is a different distance from the crankshaft axis to prevent
the engine from getting in sympathy with the airframe at any one
rpm.

nonstoprc

My Feedback: (90)

yeah, a very neat setup.

It probably can be simplified/"simulated" by replacing the engine box with standoffs. The engine plate/rubber wall nuts are still needed to isolate the vibrations. The 4 big special screws are difficult to obtain though. Another issue is how long the wall nuts can last.

MTK

Ran into a problem with the lawn tractor rubber. Just a little too small for my purposes. Purchase a larger rubber inner tube from the local motorcycle shop that's just right. The rubber diameter is 4" and the mount diameter is 4 5/8"....slight stretch putting the rubber in tension, but not so much as to make it stiff. It feels just right actually

Have the mount installed on my bench top and am just about ready to run the beastie. No nose ring yet but the rubber components are here already so I just need to build the thing. Prop is a zdz 20x10 for break in, zdz 20x12 after break in. It will be interesting how much noise the intake will generate since it is practically inside the doughnut

MattK