barry wetherell

Gasayers, Is it a 120 or a 90, altho it may have been 4/5yrs since new, but I would still let the manufacture's know,complain bitterly without insult and they may come back with a fix, may help? at least you can be satisfied, one way or the other........give it go my anzac cus

barry wetherell

the word "cus" is an abriviated version of cousin, in aus

gasayers

Thanks for all your help guys.
I striped it down last night to check for metal filings but it was clean.
I'm just going to chuck it in a box for a while, get the spitfire flying and then when I'm in a better frame of mind I'll have a go at following it up.
Like I say, it starts, runs, idles etc fantastic. But I wouldn't expose a scale air frame to that kind of vibration and throwing it in a cheap arf isn't an option and it would kill it in five minutes.
If your wondering as to my flying experience my current airworthy air fleet consists of spitfire OS 70FS. P40 50 size 1400W, mustang OS70FS, F22 1300W, F15 480W, Cap 232 OS 55, Funtana OS 55, spitfire 111W, F16 420W, Raptor 50 heli, Giant UCando OS 160 injected, ESky belt CP plus several others. Also boats with OS marine motors. I test fly my friends planes and teach with a buddy box.
I'm just saying I'm not some total novice bashing around in the dark but this is wearing me down so I think it best to just give it a break for a while.
Thanks for suggestions
Glen

http://homepages.slingshot.co.nz/~ga...obby/index.htm

ktcanuck

Could I ask what the consensus is? How many hours running in before the 120 settled down to modest vibration?

barry wetherell

Ktcanuck, From what i have read so far about 2 hrs or 2 gals of fuel, now I would have thought that manufacturer would have done this long before it was put on the "shelf" to be sold?
Now I have 2 of these to put into a twin, is there a remedy for this problem , guys??????? any one help
A.A Barry

Joe Lott

My 120SP may have been an exception to the norm, but it was tame before a gallon of Omega 10 was run through it and will idle indefinitely at around 1400rpm. I switched to CoolPower 10 after that 1st gallon of Omega with the same results. Judging by my experience with this engine, I'll stick with the SP engines for all of my scale projects. The only real problem I had was with the muffler vibrating loose with each run. I replaced the muffler with a coupling and a straight pipe of stainless steel and haven't had any problems since. I did beef up the firewall of my TF Corsair to handle the expected vibration.

andi3142001

Hi Barry,

did you run your SPs already?
From what I have learned from here and from my own experience I would say the following:
- Use fuel with fully synthetic oil, 15% oil and not more. No Castor.
- Nitro 10 -15%.
- use a bulkhead that is stiff and fixed firmly to the fuselage.

Regards
Andi

barry wetherell

Andi, not yet, got moke a mount bracket, so i can take it the club field and test run them
Thanks Barry

barry wetherell

moke....should be ......"to make"

andi3142001

Well, hope everything works smooth

Best greetings to Australia (friends of mine are just on vacations there)
Andi

numancia

My Feedback: (4)

Hi Gasayers, I too have had a bad experience with an RCV120sp. Mine was mounted on an old hack and promptly destroyed the thing!! I had run several tanks of fuel for breakin but nothing like the amount you did. The thing was put away after oiling for storage while I completed another project, well five years later I got it out to see if I could sort it out as I wanted to utilise it's compact shape to fit in a Spitfire. After consulting with Brian Winch of RC REPORT fame, I broke in the gears by using my lathe to spin the crank after removing the piston and rod. It took about two and a half hours with the use of toothpaste at first and then synthetic oil before I was happy with the way it turned over. After reasembly it was bolted to my strong test rig I use for my big gas engines and fueled up with an all synthetic fuel with 10% nitro as reccomended by Brian Winch and RCV on their web site. It started fairly quickly but I had to stop it because the header came loose immediately in spite of being well tightened. I have never been able to get it to run again!!!
I can honestly say that I am not going to put a motor with so many issues into a model that I have spent a lot of time on because I know what will happen. Another member of our club who is vastly more experienced than me has been unable to solve the excessive vibration and has consigned his to the history bin! It seems that the model flyers are being used to "develope" this motor instead of the factory getting it sorted, guess it's cheaper that way! Anyway, I now have an OS going in and I KNOW that will be OK. Numancia

ktcanuck

That's pretty depressing! Yours was an older one I guess. I am now painting my Bonanza for the 120SP. I guess I had better start running it in so it will be smooth enough by the spring for my maiden!

numancia

My Feedback: (4)

Yes it is one of the "older ones" but it does have the eccentric mesh adjust for the gears. I am sooo dissapointed because when I first saw the design and the ability to swing scale like props it seemed my wish had come true for a motor that could be burried in the cowl for my scale projects. I had dreams of a B25, Lancaster and of course the Spitfire but no way can I now consider such projects using the RCV engines. Just make doubly sure your firewall is super strong and the area behind suitably re-inforced, good luck.
Just a thought, I wonder what balance factor RCV use with the 120 SP? perhaps we could try a change of factor to try to shift the vibes away from our operating range. This is something I used to do in my distant youth when racing BSA's!! Now you know I am crazy. numancia

barry wetherell

OK, to shift the vibes, first we need to determine wether it is a rotational ,from the crank/cly or rotational from the spur driven starting boss, (in a conventional engine it would be called the crankshaft).
Is the viabrations a long the engine or across? perhaps a balance wieght on one side of the prop shaft could help, one would need to adjust it to fined the "sweet spot" or a additional wieght on the start hex, has any body had a go at this?????????
A.A.Barry

numancia

My Feedback: (4)

Having more thoughts on rebalancing the crankshaft I an inclined to think that the counter weight is much heavier than it needs to be. The "factor" used to calculate the mass of the counterweght is determined from extremely accurate weighing of the piston and its components and then a portion of the connecting rod. This is usualy done by weighing the small end with the rod suspended from its main bearing center and resting the small end on an very sensitive scale in the horizontal position.The balance factor is a percentage of the sum of those parts weighed. often around 60%. A weight of the value calculated is placed around the crank pin and then the whole crank is made to stop at any position similar to when balancing a prop. Alot of experimentation is usualy involved to find the best amount of counterweight that will balance the bits going up and down against those going round. Just my observation but there seems to be an awful lot of metal in the counterweight of the RCV 120.In the case of this engine we have an extra consideration, the flywheel effect of the driving bevel gear attached to the crank and the large spinning gear and sleeve valve/cylinder. Could it be that the mass of the driving bevel gear is working against the purpose of the counterweight on the crank? I am so desparate to get a smooth running RCV that I am prepared to experiment as soon as I can locate the right weighing equipment. watch this space!!! any one else with ideas?

barry wetherell

WEll you certainly know a thing more than me.........which isn't hard..... Consider these small suggestions
Vibrations
is it most applicable to the 120..... compare the 90 and 60
Does the cd series have the same problem, cos they have the same bevel gear layout
The manufactures must have some ideas
I will "watch this space"
thanks
A.A. Barry

gasayers

Yep, I tried a small weight on the prop and then indexed it around in 1/16 steps.
Didn't make any noticeable difference

Even tried a 4 ounce flywheel but again no change. When I thought about it the flywheel idea was dumb as the bevel gear is already a fairly substantial flywheel.

Cheers

Unfortunatley what we don't get here are a lot of comments by satisfied users who have perhaps fiddled a fix as I suppose they are out using thier engines instead of looking for solutions.
Any happy chappies out there?

bugerdup

This engine is a vibrator there is no doubt about it. The vibration is rotational due to the large mass of the cylinder/gear. It acts like a flywheel fighting against the smaller gear and the inconsistency in the power strokes.
I have mounted mine on the Great Planes vibration isolator and problem solved.

barry wetherell

That is good hear
A.A. Barry

gasayers

http://manuals.hobbico.com/gpm/gpmg2000-manual-v1_2.pdf

Is that this here? and if it's that easy to isolate I'll.............I'll...........something bad!!!!!!!!!

Manual says specificaly not to soft mount the engine.

Cheers

bugerdup

yep that's it. the rubber is very hard not like the Dubro mounts. I would rather go through bushings then have my firewall ripped off. who care's what the manual says.

Juice

I would consider myself a happy RCV user. I have a 90SP and a 60SP. Both run great. I can't remember any significant vibration on my 60SP. But my 90SP vibrated EVERYTHING loose during break-in. After each run, I found loose mounting bolts, loose muffler, remote glow connection popped off the plug, and had to pick up all my tools that were on the bench and now on the ground. Even the large clamps that clamp down my break-in rig to the bench vibrated loose. And then, the rotting wood that the bench was made of started crumbling away because of the vibration. I can't remember how much running it took before things settled down, but it was a long time. I remember more than one gallon. RCV's are known to require an extra long break-in (I hope you knew that when you bought the engine).

I can't offer any magical fix. Just keep running it. Check everything for tightness after each run, and run it again. Bring ear plugs and a magazine. Eventually it will settle down.

[youtube]http://www.youtube.com/watch?v=W5e0u7to3fI[/youtube]

Juice

barry wetherell

GUys, my thought's again, if you have to run 1 to 2 gallons of fuel through the engine, to obtain suitable vibartions levels , and I have just bought 2 SP90's, in my mind and 45yrs of modeling, the motor must have to loose most of it's compression, or why else does the vibrations reduce.
Running in Engines................is to obtain the opitmun seal between piston and cyl wall............nothing to do with lowering Vibes level
If the manufactures needed that sort of comprise ...why sell them in such a condition, it is staggering that these people, in good faith, have not come to forefront, and made their reasoning, after all, they do want to sell them
Has any body had a response from them, as to why??????????
A.A. Barry

Joe Lott

Barry, Juice gave you the best tip-just keep running it. I will add this. Be sure to run it on the bench before putting it in a model. I have a 120SP and a 60SP and like them both. I can't say that my 120 vibrates any more than my 60, taking into consideration the increased size of the engine. These engines are what they are. Some like them, some don't. I fall into the former catagory and am willing to break them in ALOT before installing them on a model. I personally would not be inclined to "tweak" the internals of the engine to lower vibration that will likely be reduced significantly anyway when the engine is fully broken in. Most of the running-in time for these engines is to seat and lap those big gears.

barry wetherell

Thanks JOE, "the big gears, lapping" did not think of that point....
A.A Barry