bjr_93tz

Yep, and the maximum delay for the "YS" cdi is about 9.5ms meaning the slower you flip it the more advanced the spark. If you can flip it at about 500rpm then you'd get pretty close to sparking just before or at TDC, any slower than that doesn't bear thinking about.

I'm just struggling with the idea that a slow flip on this OS engine would result in the CDI not sparking, I can understand this if the CDI is programmed to see a couple of pulses, calculate the rpm, then start firing which would mandate the use of an electric starter, but I'm not sure how the OS cdi knows it's going too slow from a single flip, not unless it measures the pulse width as well as frequency?

Anyway, not wanting to hijack a very interesting thread, I hope things sort themselves out as the more options we have in pattern the better.

airborne2.4

[/quote]
I did that earlier today

MTK

No, no, it's not really the issue with the 33GT. Even a 95 pound weakling can flip the prop fast enough to fire the CDI....... 100 rpm equivalent flip speed is very low speed. The only time it will not spark on purpose is when one just turns the prop over or bumps the prop through a partial turn.

I had no real problem seeing the spark when I removed the plug and flipped the prop. Sparking could be seen with the SAP CDI, DLE CDI and ZDZ CDI in addition to the standard OS. That was not the problem.

After the first couople early great runs, it simply refused to pop when flipping by hand, with any CDI attached. I went as far as making an adapter for a different carb and changed the carb to one I knew worked great, and still nothing. Then Ed assisted me with a starter and we finally got it going, but it had no power acting extremely lean. Obviously something else was wrong. I really hope hobbyservices pinpointed the problem with the alleged finding of a cracked backplate.

How they were able to make the engine run great, twice, with a cracked backplate, is beyond me!! But I am patient and I'll see for myself how it works once it's returned. Folks, I tell you this much, this is by far the strongest engine in this size I have run (I've run the SAP180, Mintor 38, ZDZ40, and have seen the DLE30 run)....that's why I am still so interested and frustrated at the slow progress

Skaluf

Guys, I got a bit of advice from OS today. You can retard the timing just a bit by adjusting the sensor 1mm counter-clockwise (viewed facing the prop hub face). This should improve hand starting. As has already been mentioned, about 1/8 or a little less throttle is also the best throttle position for starting.

O.S. is extremely safety conscience. This is one of the reasons for having the CDI not fire until a certain rpm is seen.

Steve

choihjin

My Feedback: (1)

Manual says: "The ignition module is set not to operate below 120 rpm for safety."
In my case the prop position around 1 o'clock helps to hand crank more easily. It is very tricky but it might affect to speed-up rpm.
Also someone above mentioned rich needle set affect back-fire.
With your helps to tight exhaust maniffold with Nord-Lock washer no more manifold leaks, and much easy to hand-crank right.
Getting colder here. Good Luck

selnekav

Hi,
In terms of vibrations do you see any advantage to the OS-GT33 comparing to the DLE-30 ? i am planning tio use one of those without anti vibration mount

Thanks

MTK

OS33GT vibrates to similar level which is moderately high. The very best engine regarding lack of vibration in this size range is the SAP180HP. Exceedingly smooth operation from the SAP, but even this one was soft mounted.

I soft mount all engines (up to a 110 twin.....that's as large as I have played with). I highly reccommend the use of a soft mount in any installation, excepting electrics. Everything lasts better with less problems long term.

PlaneKrazee

My Feedback: (14)

The Syssa is the smoothest but also puts out the least power. Maybe lower power pulses and mass contribute to the smooth running.

vbortone

My Feedback: (2)

I agree with Matt in regard the soft mount. If you are planing to build a 2 meter plane under 11 lbs you better install one. I tried around 10 years ago to hard mount a gas engine (ZDZ 40) in a very light airframe and almost lost the plane due to aileron flutter. After installing a soft mount the problem was resolved. I noticed that battery consumption was reduced about 40% because the servos were working less against vibration.

MTK

Hey....what do you know....Hobbyservices returned the OS33Gt.

No email telling me it was on its way, no note telling me what the final findings were, didn't include the supposed broken part, didn't say if the engine was run (it was supposed to have been) after the new backplate was installed, nada. I am left to guessing that what they told me over the phone was good enough.

The back plate appears to have been mounted so I an guessing it was run.

I will bench run it sometime over next week and post here

NJRCFLYER2

My Feedback: (42)

Nice Christmas gift! Let's getit on a test stand and see what mood it's in now!

choihjin

My Feedback: (1)

Nice to hear a good news, Matt. No more waiting to get it back, but now waiting a good weather to test the performance.
Getting colder (2 deg C, 35 deg F) and windy here, We my friend and I just did test-run of my friend's Rock&Roll, which has OS GT33 with Hatori header and E40 tuned pipe, he just got from USA. I just set LSN 1 1/8 and HSN1 3/4, that Matt you reported here. Now we are accustomed to hand start right way.
It start to run nicely. After warm-up, it reached over 7900 rpm (18x10 Menz prop), then suddenly stopped with a big bang. The silicone tube connector between Hatori header and E 40 pipe was burned out. My friend did not have time to get a correct teflon tube connector.
Even without optimum needle set, E 40 tube shows better rpm boost than Hatori canister, which gave the highest rpm 7500 on LSN 1 and HSN 1 2/3. It seems that E 40 tuned pipe enhance more air(oxygen) staying in the engine cylinder, which then require more fuel (more needle open) to burn.
We did not reproduce your enhanced power boost result yet, but E 40 definately works to boost power enough for F3A plane.
Colder and more windy weather is forcast for tomorrow.
Wish everyone to have happy holidays

MTK

I guess that the 18x10 prop must be a bigger load than something like an apc, 18.1x10. I ran an 18x12 wood carbon hybrid and to my ear it sounded like more than 7900. But I need to verify with a meter to make sure

Clearing the garage for a pair of fine benches my brother got from one of the schools he works for. 3 1/2" thick maple laminated tops, dead flat but need refinishing.

I am finally getting around to the new project I've been looking at for over a year. But first I am finishing the Mintor 38 installation in Aesthesis.

Ed I'll re-install the OS33 in Temptress. Should have that ready by Tuesday or Wed...I'll call you. Need to get real numbers as we did the SAP, 2 years ago. Engine shaft fits the standard apc prop hole so no reaming necessary on your 19x11

rexbirk

Is that a Hyde Soft Mount?

If so tell me how the mounting works on one. Is it custom made to each engine?

choihjin

My Feedback: (1)

Too cold to fly and to get a good video of OS 33GT on the Hyde mount in high speed rpm.
In this video, HSN is not properly set, but it is worth to watch the difference of vibration. I actually plan to post a better video for high rpm. Many are interested in the soft mount. This mount is first custom-made Hyde mount. I mentioned already that he did job for me and generously mailed it in express with his expenses. Mr. Hyde mentioned that it is really designed to reduce damaging high rpm vibration that causes 99.99999% of all equipment wear and damage. It still shows very stable in idle too, with low-load prop such as 18X10 Menz. I have used several Hyde mounts for YS engines, which are super-charged four cycle glow engines shaking a lot. I had noticed the vibration differences. I did not hegitate to ask him for my OS 33GT. Here is a video of running OS 33GT on the Hyde mount: http://youtu.be/ONyTGKm5VFQ

airborne2.4

Maaaaannn the OS GT33 doesn't even sound like a gasser

MTK

No gasoline engine on pipe will "sound like a gas engine". But the soft mount plays a major role. The sound is much mellower and much much quieter, very similar to the larger 2 stroke glow engines we were running on pipe.

Any sport flier or IMAC'er for that matter could soft mount his loud gas set-up and put a pipe on it for very neighborly performance. The complete package includes higher pitched props too.

In regard to soft mounting, the only mount in my opinion that truly attenuates the best is the HYde style mount. I've never owned an original Hyde but have made my own (very similar to Merles') for more than a decade. I have a thread here in RCU that describes exactly how I make mine for stand off mounting. I've made a couple small but important refinements since I posted that thread. The most important refinement was adding rubber bumpers between the two discs to avoid the slapping of the disc faces against one another that one hears are idle. A less important refinement was elimination of blind nuts to support the studs on the front disc. I simply drill and tap an aircraft ply block and install the stud through it and the the ply face. The threaded studs are glued in place. This has reduced weight by 15%

My mount for the 33GT weighs in at a scant 2.5 ozs. Don't know what the Hydes weigh

BTW- I have no interest in making soft mounts for others, at least not until retirement, so please don't even ask me. I am open to answering questions tho. If you don't want to tackle a build yourself, I suggest you contact Merle as Choijin has done.

airborne2.4

[/quote]
Would you mine posting the link?

MTK

Would you mine posting the link?
[/quote]
No, except I forgot how to make a link. Maybe Bob can help on that one............

MTK

No, except I forgot how to make a link. Maybe Bob can help on that one............
[/quote]


Lessee if this comes through:
Try http://www.rcuniverse.com/forum/m_62..._3/key_/tm.htm

airborne2.4

Looks like it

Thanks

cmoulder

Matt,

[link=http://www.rcuniverse.com/forum/fb.asp?m=9741649]LINK[/link] to link how-to.

For those of you making your own soft mounts, [link=http://www.rcuniverse.com/forum/fb.asp?m=9692415]this[/link] might be of help as well.

MTK

Thanks Bob....

Another important thing about rubber prep. After washing the anti-blocking agent off the rubber, I've found that the rubber will adhere best if fresh rubber was exposed.

This is what I do: with a dremmel fitted with a drum sander, I freshen up the rubber where it adheres to the ply rings. Basically I remove the gloss from the rubber. Once fitted, the rubber sticks extremely strongly to the ply using thin ca. No need to lead by first putting on thick ca then flipping the rubber onto the plywood. I simply assemble, then wick the thin ca in place. The rubber will tear before the bond gives up. It's the best you can do

Don't bother with the rubber filled ca. Thin ca works best

rexbirk

MTK,

Explain your soft mount to me. I looked at your post of it's construction. From what I see the rubber around the outside of the mount is what holds the two plywood discs together. What is the purpose of the balsa core?

PlaneKrazee

My Feedback: (14)

Balsa core spaces the plywood discs apart so you have an area of rubber that absorbs vibration and helps prevent gluing the plywood together during assembly.