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Russian Diesels - OTM Striz - renovation and new handmade conrods Empty

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Russian Diesels - OTM Striz - renovation and new handmade conrods Empty Russian Diesels - OTM Striz - renovation and new handmade conrods

Post  czarobest Tue Jul 20, 2021 3:56 am

Hello, I got a package with some motors from a friend from Polish RC forum. Among them were 3 OTM Striz diesels (ОТМ СТРИЖ) in average condition Wink.
They were very stuck and dirty, it was hard to open them and when we managed to do it we found out that in each one the connecting rod is in bad condition. Crooked, loose and cracked.

However, I already had experience with creating a connecting rod for OS's 10LA (video witch information about this and firing - https://youtu.be/DR4dyyOCEpI) so I tried it now as well Smile.

Managed to do it again so I am very happy Very Happy. You can see the whole process here in the photo album - https://photos.app.goo.gl/3qj1s1ZCgGaSSZcm8
Compared to the original, I added a lubrication hole in the upper part with a diameter of 0.4mm.

Russian Diesels - OTM Striz - renovation and new handmade conrods Striz_11
Russian Diesels - OTM Striz - renovation and new handmade conrods Striz_12
Russian Diesels - OTM Striz - renovation and new handmade conrods Striz_10
Russian Diesels - OTM Striz - renovation and new handmade conrods Striz_14
Russian Diesels - OTM Striz - renovation and new handmade conrods Striz_15
Russian Diesels - OTM Striz - renovation and new handmade conrods Striz_13

Here are before/after photos of the restoration, there are more photos with each engine in the albums:
Engine #1 - https://photos.app.goo.gl/pi6moQZPxka4qp328
Engine #2 - https://photos.app.goo.gl/jjhADT1fGVFUu3f87
Engine #3 - https://photos.app.goo.gl/uWmX6di7YmNfr4499

Russian Diesels - OTM Striz - renovation and new handmade conrods Otm_st12
Russian Diesels - OTM Striz - renovation and new handmade conrods Otm_st10
Russian Diesels - OTM Striz - renovation and new handmade conrods Otm_st11

Russian Diesels - OTM Striz - renovation and new handmade conrods Otm_st13


I started the engines, of course, so few info about first engine and video:
Prop: MA 8x4
Fuel: 42% Kerosene, 35% Ether, 12% Motul 710, 10% Castor Oil and 1% Mannol diesel additive
Max stable RPM: about 9900 (~100W, 0.13KM)



Unfortunately second and third engine have weaker compression and didn't want to start on above mixture, so I made new one with more castor oil Smile.

So second motor:
Prop: MA 8x4
Fuel: 34% Kerosene, 33% Ether, 6% Motul 710, 25% Castor Oil and 1% Mannol diesel additive
Max stable RPM: about 8600 (~70W, 0.09KM)



And third engine:
Prop: MA 8x4
Fuel: 34% Kerosene, 33% Ether, 6% Motul 710, 25% Castor Oil and 1% Mannol diesel additive
Max stable RPM: 9800 (~100W, 0.13KM)



Overall I'm very happy and satisfied that I gave new life to the motors and that my handmade connecting rods work Smile. And now I'm getting on with the next engines Very Happy
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Post  getback Tue Jul 20, 2021 5:59 am

You should bee Happy and Proud of your achievement , excellent job on the con. rod replacements . The engines sound really good !! Very Happy Very Happy Very Happy Thumbs Up
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Post  rsv1cox Tue Jul 20, 2021 6:48 am

@getback wrote:You should bee Happy and Proud of your achievement , excellent job on the con. rod replacements . The engines sound really good !!  Very Happy Very Happy Very Happy Thumbs Up

X2

Got a chuckle out of the first few seconds of your first video. Sounds like one of those "hit and miss" engines.

Nice job creating those connecting rods, little things can yield big results.
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Post  Ken Cook Tue Jul 20, 2021 4:45 pm

I own the OTM COLIBRI .049 diesel. I love the looks of the engine but it doesn't run. I'm pretty close to giving it the sledge hammer treatment. I've had many issues with the Russian school project engines. The OTM got my attention when I discovered that the liner was hardened. I actually have a freeflight plane ready to go for this engine but despite all kinds of tries, it won't run. I get a occasional pop but that's about all the excitement one gets. I had a new contra piston made for it. The stock one was so loose it was going up and down in the cylinder. The crankshafts are somewhat long and thin in diameter on this engine so one needs to use caution. It needs to run however in order to break.
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Post  czarobest Wed Jul 21, 2021 3:25 am

@getback wrote:You should bee Happy and Proud of your achievement , excellent job on the con. rod replacements . The engines sound really good !!  Very Happy Very Happy Very Happy Thumbs Up
Thanks  Smile

@rsv1cox wrote:
Got a chuckle out of the first few seconds of your first video.  Sounds like one of those "hit and miss" engines.

Nice job creating those connecting rods, little things can yield big results.  

Thanks too Smile. Actually sounds a little bit like "hit and miss", however, this video is slowed down about 10 times and the engine is with little unscrewed compression Smile


@Ken Cook wrote:       I own the OTM COLIBRI .049 diesel. I love the looks of the engine but it doesn't run. I'm pretty close to giving it the sledge hammer treatment. I've had many issues with the Russian school project engines. The OTM got my attention when I discovered that the liner was hardened. I actually have a freeflight plane ready to go for this engine but despite all kinds of tries, it won't run. I get a occasional pop but that's about all the excitement one gets. I had a new contra piston made for it. The stock one was so loose it was going up and down in the cylinder. The crankshafts are somewhat long and thin in diameter on this engine so one needs to use caution. It needs to run however in order to break.

Hmm, have you tried, as I have, making another fuel with a high castor oil content? The third of my OTMs from the topic has very poor compression and didn't even start running on fuel like the first one. However, after doing a mixture with lots of oil it "sealed up" and worked really good Smile. You may also want to add some sort of fuel additive . Congrats on making a contra piston, I wouldn't have made it Smile.

In addition, unfortunately, as far as I know Russian engines had this to themselves that the quality of different motors from the same factory was very different. And some runs great and others wouldn't. Although it was mainly what I heard, because so far, apart from the RYTHM 2.5 engine, these are my only Russian motors (but I still have some Russian engines more to renovate Smile). And in fact, I've also heard to be careful with connecting rods and crankshafts, which can easily break in these engines.

Good luck and I wish that someday it will work out Smile.
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Post  KariFS Wed Jul 21, 2021 7:48 am

Good work on the rods! I’m impressed Cool What material did you use?

I have a 1.5cc Webra with a loose rod, might be an interesting excercise to try to make a new one.
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Post  czarobest Wed Jul 21, 2021 8:12 am

@KariFS wrote:Good work on the rods! I’m impressed Cool What material did you use?

I have a 1.5cc Webra with a loose rod, might be an interesting excercise to try to make a new one.

Thanks Smile, I used PA9 / 7075 aluminum same as the OS 10La (works well with 17 600 RPM Smile). It is easy to machine and durable.

I encourage you to give it a try because it's pretty easy and I wish you luck! Smile
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Post  aspeed Wed Jul 21, 2021 9:59 am

@KariFS wrote:Good work on the rods! I’m impressed Cool What material did you use?

I have a 1.5cc Webra with a loose rod, might be an interesting exercise to try to make a new one.
Likely the 7075 aluminum is a wise upgrade, but maybe it would be easier to press out the bushing, and make a new one if it is just worn? Reminds me that I have to make a rod for an old Supertiger X .15 that split the bottom of the rod on the first run---40 some years ago. Maybe soon?
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Post  ffkiwi Thu Jul 22, 2021 6:53 pm

It is not especially well known that the OTM Kolibri is a Russian-ised copy of the Webra Piccolo....so close that Piccolo parts will drop in and vice versa-so there is one possible option for improving your QC issues-fit Piccolo innards. A second point -also pertinent-Piccolos were not particularly nice handling in their day-and benefited from a high ether content fuel-by high ether I mean 45% ether-with the usual reduction in the other two components whilst keeping the oil at a suitable level..ie >20% Piccolos were quite short stroked compared with other diesels of similar size-so high revving. They will not thank you for throwing on an 8x4 as if they were a Mills 75, MP Jet Classic or DC Merlin.

The OTM being effectively a clone-also follows these characteristics-with poorer overall quality added to the list! I have two-both run well-but are pigs to start-and require the delicate use of the electric finger when cold. If you have the skills -small things like a better gudgeon pin etc can improve the life of the OTM.

ChrisM
'ffkiwi'

PS. You will find this quite informative: http://sceptreflight.com/Model%20Engine%20Tests/OTM%20.048%20Kolibri.html
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Post  Ken Cook Thu Jul 22, 2021 7:04 pm

I'm still not going to give up on the sledge hammer, I'll be sure to post pictures. I tried the electric starter. Fuel is good, so I know that's not the issue.
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Post  fps60 Sun Jul 25, 2021 5:13 am

Ken, you'd better leave it as is. They either run or not, I've known that from my childhood. Of course, you could resolve upon a major intervention but there is no point, though may be just for the sake of curiosity.


czarobest
Fuel: 34% Kerosene, 33% Ether, 6% Motul 710, 25% Castor Oil and 1% Mannol diesel additive

Very interesting fuel mix. How did you figure it out?
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Post  czarobest Wed Jul 28, 2021 4:45 am

@fps60 wrote:
czarobest
Fuel: 34% Kerosene, 33% Ether, 6% Motul 710, 25% Castor Oil and 1% Mannol diesel additive

Very interesting fuel mix. How did you figure it out?

To be honest, I'm still experimenting with diesel mix Smile. I modeled a very basic mixture of 1/3 kerosene, 1/3 ether, and 1/3 castor oil. In the basic version of my fuel (I fired up the first of these three engines on this mixture) I used less oil, because I think that such a large amount is not needed if the engine is in good condition. I used synthetic oil for 2T engines to take advantage of its benefits like counteracting carbon build up etc. And also castor oil to take advantage of its benefits in extreme conditions. In addition, I used an additive to increase the cetane number (I saw that someone already used similar, probably even here on the forum). I don't have access to agents such as Amyl nitrite hence the use of something like this Smile. However, because 2 engines would not start and had weaker compression I decided to make fuel with a large amount of castor oil which is thick and "improves" compression, which as you can see had an effect Smile
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Post  gkamysz Wed Jul 28, 2021 10:06 am

Witam,
You can get some high viscosity 2T oils. In Motul something like 800 or Kart 2T has viscosity similar to castor oil. Usually these are marketed as premix only racing oils, not for injection, but check the spec sheets. Also consider racing castor if you're spending the money on synthetic. Maxima Castor 927 runs extremely clean. Though engine grade castor oils are disappearing pretty quick.

If you are using Mannol 9955 you have to check the data sheets to see what it's made of. 2-EHN is what replaces amyl nitrate, and 9955 contains only 10-37.5% I don't know if anyone found a product similar to Amsoil ACB (100% booster) in the EU.

Greg
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Post  fps60 Wed Jul 28, 2021 10:44 am

Thanks, I see, I'm interested because,

first, I'm a devoted fan of compression-ignition engines now intensively using PAW and, to a less extent, Enya diesels, and

second, following recommendations of one experienced vintage combat flyer from the UK, some time ago I'd switched to synthetic fuel and, I should say, I'm quite happy with results.

I've also chosen to go with Motul 710 2T that I use as 100% lubricant for engines which have passed full run-in cycle and run perfectly free. I've found out that castor oil replacement with Motul significantly improves engine performance without any notable adverse effects, especially in cold weather. The only precaution you should keep in mind concerns those engines which have already run long with castor oil. Such an engine needs either cleaning or running on fuel with sufficient content of synthetic oil at a moderately high r.p.m. (so that to warm it up but to avoid overheat and leaning) until it stops spitting black.

And to run in a new diesel engine, I use fuel with Castor 927 either without cetane improver or with its content not above 1%.

I use IPN (isopropylnitrate) as a cetane booster additive at a level within 1% up to 2% (1.8% in most cases). It works great but I'm also going to play with Mannol 9955, it looks attractive in terms of cost and availability.

Ether content is within 30% up to 35% depending on weather and engine type.

Here are my early experiments with PAW 249 GT on Motul 710 2T:



And this is PAW 19 TBR Combat Special which had been recently run in with Castor 927:

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Post  fiery Wed Jul 28, 2021 9:06 pm

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