Talk about resolution! Excellent for smaller items. Nice thing about this exercise is that it makes us zone in on all the little bits that add up to a lot.

I almost got a scale with 1g resolution but a higher upper limit, but the digital postal scale is good for all-up-weight. A tenth of a gram is good enough for the small stuff now.

I got really lucky at work a few months ago. We were cleaning the RD lab out and EVERYTHING was being tossed including a 1.5 KG capacity Lab View scale with 0.1 gram resolution. Yours truly walked away with a very nice scale. Particularly useful in getting epoxy ratios down to the gnat's a..

Matt

Nice catch on a superb set of scales, Matt.

Good idea about the epoxy ratios! I hadn't thought of that before because I never had scales that could do it. Figured that estimating the size of the blobs was how everybody does it. Even if the resin and hardener densities are slightly different, it's still going to be very close to perfect in the small amounts we mix.

Concerning the Xoar e-props for the SAP-180 hybrid prop mod, I got two 18x12s in the mail yesterday, as well as a couple of APCs. One of the Xoars weighs 49.7g and the other 45.2g, with the APC 18.1x12 at 124.4g and the 17x12W at 132.1g. Clearly, the modified props (even if they weigh 60g) are going to make a significant difference in rotating mass.

If there isn't anything similar commercially available by the time the weather warms up and I can work out on the deck, I'll have the materials assembled to make them.

Bob,

For epoxy to reach maximum mechanical properties it shouldn't be resin rich or hardener rich. It should be very close to correct stoichiometric ratio. For adhesive types of epoxies, if the viscosities are pretty close, the time honored technique is fine.

For finishing and laminating resins one uses more material and it should be done either by weight or volume depending on mfg recommendation. I will typically use laminating resin for setting things like firewalls, landing gear sockets and practically all other high stress areas because the plastic will wet out the reinforcement better and produce a lighter bond in the long run compared to adhesive types

Some epoxies have the same density for parts A and B so the same ratio for weight and volume methods will give the same results. Aeromarine Epoxy is one such material (JGreer Co). Most do not, so volume and weight require different ratios. A good scale comes in handy since doing it by volume accurately requires syringes which tend to stick

Just completed applying top coat to mine. Once cured, I will polish and wax it to high gloss. BTW, what did the 18x12 cost, delivered? Nice prop eh?

Matt

Good info on the epoxy usage.

Now that I have an accurate way to measure, I'll start paying closer attention to it.

The Xoars from gravesrc.com were $16.40 each and shipping was $7.46 for the package.

Matt and Bob,

Just obtained a custom vibration isolation mount for the Syssa. Actually it was plywood, and balsa yesterday morning. Made mostly from scraps I had laying around. I had to purchase a tube at a mower shop but it was only $11. I did two layers of rubber and it mad a really stiff mount. Instead of end grain balsa, I used 1/4 inch dense balsa sheet and cut the spacers. I put 8 bumper pieces between the disks to stiffen it up at idle. The only thing of concern is that the way I assembled the back plate I will need to watch the length of the firewall bolts. Guys, thanks for the motivation.

Looks great! Did you make sure and wash the rubber really well with soap and water first and with rubbing alcohol second? The release agent used on the rubber has to be removed completely in order for the rubber to stick long term

Matt

FlyEng, Looking Good, MAN!!

It took me a minute to see how you did the firewall mount for the back ring, but then I saw what you meant by having to watch the bolt length since they will be coming from behind the firewall. It will be a little tricky to align and install, but it's something you have to do only one time. Once you're happy with the position, perhaps use red Loctite and you won't have to touch it again.

When you have a chance, it would be nice to see some pictures of how you did your spacer rings. I have been thinking of alternate ways to do that.

Good job!

Matt and Bob,

I used rubbing alcohol and scrubbed the tube with a cloth. Then I roughend the end by sanding and then cleaned with alcohol again. The many little cuts in my fingers from splinters etc. really showed up when dowsed in alcohol. My day job keeps me at a desk so the skin takes a pounding when wood working and such. Especially when I'm being stupid and holding parts instead of clamping them when sanding and cutting. Fortunately it's been some time since I stuck an exacto blade through a finger. Scar is still there though.

I may still drill through the front and install bolts in the back. Is there a down side to this? Bottom line was that I didn't have the proper bolts with domed heads to add them and I got in a hurry wanting to finish. It defintely will be tough to mount in the Focus if I leave it like it is.

I didn't take any progress photos mostly cause I didn't think it would turn out anywhere near as good as it did. I did buy a circle cutter at ACE for about $10. It made the second and third disks much faster. Oh yeh, I cut three. The first which took forever to make was cut from 1/8" aircraft ply. I decided it wasn't thick enough. And, after cutting and sanding and sanding and sanding to get it round, I had to find a better way. Thank you circle cutter. I'm sure it will be of use in the future. Oh, and it made cutting the balsa spacers a piece of cake. The only issue with the dense balsa spacers was that the CA didn't wick completely through. I thought about drilling small holes all over both disks to perforate the depth but I chose not to do that. I hope it will be okay.

Cutting the rubber with a single edge razor blade on a plastic cutting board worked really good. I have a part of a cutting board left over from cutting firewall backers for flat bat combat planes. I finally found a use for it. That thing was stuck behind a box and will get used a bunch more for cutting balsa etc. DUH. Never thougth of that before. You know, cutting board means preparing vegitables, fruit, and meat. It doesn't usually come to mind to cut balsa, rubber, covering, etc. But using the cutting board with a stiff straight edge after a couple of practice cuts, I was able to make the final inside band with one cut. The outter band I trimmed in place once it was glued.

Looking forward to pointers on the engine. I'm going to start with the Xoar props mostly cause of the weight. Man are they are nice lookign, too. Balanced it by spraying clear gloss on the lite blade. Didn't take much either. Very nice props.

Thanks for the kind word guys.

One small caution....drill through with the small bit at the desired spots. Then use a collar to set the depth on the drill bit for the larger relief hole. You can guess why I know that. Any type of collar will work, even rolled masking tape.

There is no down side I can think of, unless you don't have fairly easy access to the back of the firewall to install blind nuts....then it could be a pain. BTW, 3 or 4 4-40 bolts is all you need to mount the soft mount to the firewall, but 6-32 is probably easier to work with.

These mounts are a little stiffer than the commercial units (assuming you can even buy a commercial unit for the SAP engine) but the nose ring is not necessarily a must. I've done multiple snaps with my test bed and the mount damps very quickly. The stiffness has not hurt my servos in many hundreds of flight. In my primary plane I am still using original servos with a similar mount up front

I've seen commercial units allow engine flop all over the place on the ground when the engine's nose wasn't supported, simply by revving the engine up and down.

Another BTW, 1/8 A/C ply is okay to use. I use 3/32" or 1/8" normally. On the spacer, if it's firm balsa you're fine.

Matt

FlyEng,

I don't have nearly the depth of experience on this as Matt, but the photo below shows about how much room there is to work with - not much!! None of our custom mounts are the same thickness, but I would imagine they fall within a 1/8" range. Depending upon which stand-offs you use (6.25" Syssa standard?) you could even end up with 1/4" less space than I did with my spliced stand-off arrangement which was right at 6" for the soft mount-to-thrust-washer distance.

In short, I think it will be a lot easier if you use Matt's method to tunnel in from the front.

BTW, After this photo was made I epoxied triangle stock into the corners where the motor box and firewall meet. It is very rigid and does not need cap pieces of ply for the top and bottom of the motor box. That sucker ain't goin' nowhere, especially with the soft mount taking out the sting.

Bob,

Looks like we are snowed in til spring. Another 6" or so fell today. On the bright side, I've made serious progress on converting the garage into building space, especially running electricity all over the place. I finally have some light

Planning to do some bench running this weekend with the 18x12 hybrid. I'll report the findings here

Matt

I went flying yesterday in very heavy winds. My Ultra Stick with an OS 120 was just jumping all over the place. I am thinking of a pattern plane for my Syssa, what is the best pattern airframe going these days, especially since I do not seem have the luxury of calm flying.

There are several good planes out there and they can be from relatively inexpensive to quite pricy. You can't really go wrong with the plane Bob and FlyEng have. It has won at the highest level in the right hands.

The Xigris version 1 is pretty nice and relatively inexpensive for what you get, but you have got to know how to finish it. A little more money gets you the Valiant designed by our own Bryan Hebert. This plane is pre-finished excepting equipment. There are several others....prices can go through the roof.

If you like kits that you can build from relative scratch, contact Hester for the BM. There is also the Pentathlon by Hunt. You have choices.

If you want "The Best" it's gonna cost you...bottom line

MattK

...and then [link=http://shop.singahobby.com/?q=node/13454]keep going...[/link]

How about $3738.00 for an ARF airframe? Not at all difficult to spend more than $6k for a ready-to-fly model.

Stock Focus II with all stock hardware, SAP-180 with included Pitts muffler and decent servos could run well under $2k, maybe less than $1500 depending on what you already have in your parts stash. Might not make weight (i.e. under 11 lbs) and would not technically meet noise requirements for pattern competition, but would make one heckuva fun sport plane!

OK, best was not the word I should have used, I was thinking more like:
http://www.kmp.ca/product_info.php?c...5c2a4a226f9de0

Yes, we also got a lot more of those heavy, wet flakes that melt and then seriously freeze the turf for a long while. Got used to not having 'real' winters for a few years... looks as if they're back! I've been out flying the Avistar trainer off the snow with skis.

Well at least you've got a nice shop to retreat to, and it's much easier to work when nice weather isn't pulling us outside.

VERY interested in your results with the hybrid prop!

What do you guys have again?

The link goes straight to sign-in, but I assume you were looking at the Adrenaline 2M.

Looks good, construction- and price-wise, but weight is listed as "11 to 14 lbs", which means it would likely take a lot of effort and aftermarket bits to keep it light, therefore driving up the total cost. Surely there are construction threads on RCU where you can see what actual finished weights are coming in at.

But if you just want a smooth and precise flying model for practice, I'll bet it would be excellent.

The Focus II at 10.5 lbs is very light and peppy, but definitely wouldn't be at 12.5 lbs.

[link=http://www.piedmontmodels.com/FocusII.html]Focus II[/link]

Dan "Gungadin" also is doing a Focus II w/SAP-180.

[link=http://www.rcuniverse.com/forum/m_4957760/anchors_4957760/mpage_1/key_/anchor/tm.htm#4957760]Here[/link] is a thread on the Adrenaline.

Ok, it did not get a good review from a gentleman in OZ: "<span class="Apple-style-span" style="font-family: Verdana, Arial; font-size: 13px; -webkit-border-horizontal-spacing: 1px; -webkit-border-vertical-spacing: 1px; ">the adrenalin 2m is of fairly poor quality and is not that well designed". OK, I am not planning on competing, but want a smooth sport plane for the Syssa. I keep going back to an Extra/Edge/Sbach...</span>

None of these will fly as well as the Focus II. If a top of the line sport plane is what you are looking for, the Focus is definitely THE BEST sport plane around. It is also one of the best competition planes from 7-8 years ago. Point is that with this plane you will have a very capable platform to either bore holes in the sky or do sequences to pattern standards. That can't really be said for the other planes you mentioned.

If 3D is what you want, then the Focus is not the better plane

MattK

I have an original design called the Temptress. She's been with me going on 7 years. A truly excellent platform and stll flying great as my primary
I have an Alliance that needs a little work to get flying again, work I can't put into it right now. I would like to sell this one
I have a new design, Aesthesis, on the board nearing completion and will be flying it this spring...SAP 180 up front
And a new project starting soon which I will call Derivative...set-up around the SAP 180 also. Planning to make full molds on this one and play with partial kits.

Matt

Hard to do better than [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=SEA5500]this[/link].

I have been extremely impressed with Seagull quality, and with a Vess 18A this would be an oustanding performer with the SAP-180, at a very attractive price. And free ground shipping, HUGE.

IMAC precision routines have a lot elements in common with pattern.

You might look at the N E Aerodynamics Aquila. They are on sale at a good price.