flywilly

My Feedback: (121)

Ok Matt,
I think I uploaded the photos successfully.
I did a little more research and discovered that the YS classic fits the Hyde 91-115 mount with the same slight interference fit. Hmmm; so I got out some engines (a Hanno, A YS .61 LS and a YS .61AR) and
did some measuring. I discovered that the mounting lugs on the Classic are 1mm wider than the LS or the AR and 1.5mm wider than the Hanno. The mounting lugs on the LS and AR have been machined square, but the lugs on the Classic have not been 'trimmed'. My guess is that YS skipped that operation to save a little bit of $$ when making the Classic. I would be curious to know if the YS 60SR (their current hell engine in that displacement) has the lugs machined. It appears that they are in their promotional photo.
The Hanno fits the 40-80 adjustable Hyde mount perfectly as do the LS and AR...
-Will

Huang

My Feedback: (27)

Thanks for the investigation and photos Will!

Interesting find on the trimming of the lugs. When I was mock fitting another Aurora a few months back it was apparent that the Classic was wider than the Hanno, and also seem slightly wider than the original LS as well - that explains it.

On the Hyde mount: looks like the header clears with plenty of space, but slight interferes with the triangle support of the beams. That triangle web could be dremeled away but the rails will be even more flexy than they already are. Any concerns or loss of power you think? Would the .40-.80 one fit or do you need the 91-115? There's a 3.3oz difference in the weight of these two sizes so I'd like to go with the smaller if possible to save weight.

doxilia

My Feedback: (3)

No kidding Will! I see what you mean.

That's a bit of a nuisance.

Absolutely! That's it; they didn't square them off on the sides!

I suppose if one were to move the engine forward on the mount the trimming of the gussets might be minor. Not something one wants to do though with these nylon type mounts. Might affect integrity in the long run. What if one were to simply take off the GP adjustable mount and bolt on an aluminum 20 mm custom mount (or the split type widely available)? Is the bolt pattern too shallow height wise on the Hyde section? I know those GP adjustable are very shallow which I'm sure is so that most all engines (RE included) can be accomodated. The BHE mounts (from which the GP adjustable is derived by the looks of it) were a little bigger but the RE headers passed anyway - at least for the "higher" exhaust (non round) port engines such as the YS, OS, Webra, OPS, etc. The round port engines such as the Rossi, NovaRossi might always be a problem with a square or round (rather than split) mount due to their round exhaust nozzle and the fact that they have (NR in particular) a lower location of the exhaust port.

David

PS Below are the photos of the "lightened" beam FRP mounts I picked up. They come in small (35-55) and large (55-110) sizes. We'll see how they fair strength wise when they arrive. Nice things about them: 1) bolt engine to mounts to keep them rigid and spaced, 2) bolt mounts to FW, 3) slide engine in position on the beams for proper spinner spacing, 4) tighten bolts and fly! It even allows one to change spinner brands if desired - without or without backplate recess. Engine misbehaving? Swap out for any other 52 mm bolt width engine...

doxilia

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Mmm... One question:

In the Classic, is there a slight filament like imperfection going through the YS 61 R text on the left side of the case? Both the R and AR had this (but not the S) and it must have been a piece of debris that got into the mold when the crankcase was being cast. All R and AR LS that I have seen have this imperfection so it's not a batch case issue in the crankcases but in the mold itself.

If the imperfection is there, then the same mold is used and the cases should be generally (dimensionally) identical, except for the lugs which as Will pointed out might be the result of not machining them square off after casting. If the imperfection is not there, well, then it is a new mold and the dimensions could have changed slightly... :-)

Matt,

if there is a difference in size of the Hyde section diameter keep that in mind too as I ran into issues when sizing such a mount in a draw up I was working on. The larger mount didn't fit width wise since the rounded sides take up more space than typical "square" side mounts. There might be enough space in the Atlanta but check with the side thrust as it puts the mount closer to the left side of the FW - obviously.

David

Huang

My Feedback: (27)

The "filament like" imperfection is definitely there on both of my Classics. When I got my first Classic I thought I got a one off but then I checked my other YS LSs and it was there already. So definitely from the same mold and has been that way for (20+?) years. Not machining the Classic to square off is a very interesting find, wonder if this was intentional or an omission for the small batch production.

David, I'll check the width of the firewall, thanks for the reminder. That FRP mount looks great! Where could I acquire one? Do you think it's rigid enough?

It's kind of crazy and cool we could talk about engine mounting dimensions and mounts between OS/YS for 3 pages!

Huang

My Feedback: (27)

By the way, here's the similar Hangar 9 mount I mentioned earlier. Definitely rigid if you can live with the slightly higher weight and hard mounting. $9.99 and you're set, swappable between all OS/YS and other including 2C & 4C up to 1.50

http://www.hangar-9.com/Products/Def...ProdID=HAN2033

doxilia

My Feedback: (3)

Hard to believe! You'd think a new mold might have been made over the years. Maybe it is very critical dimension wise as well as expensive so they figured why make a new one when the old one works. They must have said: who cares about our tarnished logo! Then again, we're talking about the Japanese here (perfectionists) so it's still surprising.

Yes, not bad eh? I picked them up on eBay (did I just say that!? Wait, I can actually use those four letters on RCG, whew..., close). $4 for the small, $5 for the large. ProtonRC. Even the hardware looks decent. The H9 looks pretty much like the same thing and for $9 it certainly beats the OS mounts at, what?, $32 - yessir! If you want to wait until I get them, I can offer some impressions (although the friendly white giant, Winter, has set in so I won't be running engines any time soon). I picked up a pair each. How bad can they be... hopefully good!

Errr... yes, something's gone awfully astray in our neuron banks.

I'm just waiting to hear back from SV on his custom aluminum mounts... Well, at least that's my excuse for loitering here.

David

flywilly

My Feedback: (121)

Hey guys,
I just wanted to propagate this 'insanity' for a bit longer .
The Gator mount is not really suitable for .60 size engines: the mounting dimensions are 3 3/8" wide by 2 3/4" tall. The inside spacing between the beams is 1 7/8" which doesn't allow for much material for the engine mounting bolts to hang on to.
I also wanted to comment on the soft mount power loss 'myth'. There has been quite a lot written about the vibration and noise reduction benefits with some legitimate research to back it up. Almost nothing about power loss, probably because any that may occur is inconsequential to the airplane's performance. I have flown 2 of my own airplanes with and without soft mounts. No performance change was noted but a noticeable increase in noise without the soft mount.
Lastly, I checked out the Dave Brown (now Ohio R/C) soft mounts and discovered that they are all on sale. I suspect this means that when the existing stock is depleted there will not be any more produced. I believe this is also true for the Budd Engineering mounts.
Keep us posted on your progress with the Atlanta, Matt. Winter has definitely arrived for David and, unfortunately, for me too (I don't fly much when the temperature goes below 55F).
-Will

stuntflyr

I'm agog as to the content of this thread! I must be an eyeball guy, I just measure my engine, drill the holes and belt sand off what doesn't agree with the engine or model. Thanks for the info, especially the list of available mounts that work.
Chris...

Huang

My Feedback: (27)

Will, thanks for taking time to post all the info! A wealth of info for builders.

One clarification, I wasn't talking about soft (vibration damping) mounts taking away power. I use soft mounts whenever possible - they reduce vibration and make long lasting airframes/components. The planes are quieter and smoother to boot and I've not noticed any power loss as long as its a quality mount.

I was referring to low quality nylon beams (whether on a hard mount or soft mount) that are not strong enough and can shake and flex under power. Those can lead to MORE vibration under power and some power loss.

The original Hyde mounts were awesome. I noticed the "adjustable" Hyde mount used adjustable nylon beams which did not look as sturdy as their aluminum beams, and hence the question how they perform.

I'll update on the Atlanta as I go along...