A while back I remember reading a post that described a certain condition that an engine spinner was creating a vortex in front of the carb and causing deadsticks in the air. I have searched for this post to refresh my memory but cannot find it. I have an engine right now that runs perfectly on the ground and transisions flawlessly. It has been peaked out and then richened up about 1/8 to 1/4 turn. It will take off and then starts to die, bring it back to idle and it runs again. If it gets to full throttle and when the airplane is up to speed it runs great. When I slow it down around mid range, it starts to run irraticaly again. If it take it straight vertical it goes up a ways and when it slows down it starts to die again. I thought originaly that it was too lean so I richened it up more and end up with more problems. The plane leaves a great vapor trail in the air so I am pretty sure it is rich enough.

I already switched out engine for another one but after I took this engine off, I remembered that the fix for the engine in the thread I read was to just change the spinner and the problems went away.

Does anyone remember this thread?

Hi John: I just found your post, and while I never saw the post you are looking for, my first thought as a retired mechanic deep into models, that the first thing to do is remove the spinner on our plane, and see how the engine runs. Could be an engine problem rather than a spinner one. From my readings, a spinner directs the airflow towards the blades, and stops the turbulence created by the firewall.

Get back to me how the engine runs without the spinner.

Cheers!!!

Rich

The first job of a spinner is to reduce the drag of the center area with the boss and thick, structural centers of the props. That and all of the other things behind the spinner gives somewhere around 2-5% drag reduction. I'd like to see that thread too. What kind of model are you flying? Maybe some sort of simple protrusion will act as a spoiler?

The plane is an Tower Hobbies Uproar that I put on floats. I didn't think about taking off the spinner before I removed and replaced the engine with another that I had. I raced it around the yard on the floats and it does just fine, but as soon as I get it in the air and up to mid throttle speed, it starts to run irratically. Kind of a off-on-off-on thing going on. Here is a picture of the model hanging in my garage.

I think it was right here on RCU that I saw the other thread, and it left everybody baffled. The thread starter knew what the problem was before he posted but wanted to make it a guess what the problem is thread. It had everybody stumped. He then said that changing the spinner solved the problem completely.

I just found it guys. Here it is. I will have to read it again to get all my facts straight. [link]http://www.rcuniverse.com/forum/m_11135981/mpage_1/key_/tm.htm[/link]

Interesting.  You can take some silicon tubing (or a piece of an exhaust deflector) and make a ram scoop out past the spinner "vortex".





 

The software used by this forum is the worst by far.

Search function is a joke!

+1. The search function does suck. It rarely finds "current" posts, mostly all stuff from 1yr+ ago.

Good job! How did you find it? Did you use the search engine and what search terms did you use? Seems that a topic that could be of use to many of us could use a more specific title to make later searches easier?

Thanks for finding it.

Sincerely, Richard/Club Saito #635

Well, it ended up being pretty simply really. I originally typed in vortex because I thought that was in the artical somewhere and would not be that common with other threads but turned up nothing in 6-8 pages. So I definently knew it had something to do with the spinner and after searching spinner, I came up with the title that I remembered on the second page. Now I have only had luck searching in site specific forums. If you don't remember what forum you saw something in, then I think you might be out of luck.

Yes, and the programmers are well aware of the search problems. Things are moving fast now with the new owners. You may have noticed the big bump up in speed. RCU has now migrated 100% to new and faster servers. The new software is almost ready for beta. I've seen it and had a couple of days to try things out. If you haven't beta tested big software packages, you need to be patient.

While I agree with you that this older software is full of problems, I have to disagree that it is the worst.

I'd suggest that the problem is fuel foaming in the tank. The tank may no have enough padding around. The symptoms are classic: when on the ground or held there is enough damping to prevent the fuel from foaming. In the air, the vibration increases foaming the fuel.

Why doesn't RCU use the same software as 100% of all the other forums I frequent? For example: www.rcgroups.com www.lxforums.com www.dodgetalk.com

All have similar software that allows direct posting of PIX W/O problems & super effective search functions. Don't try fixing what you have, dump it for something that works.

And why has the direct posting of PIX started to leave URL text before & after the picture?

I'll look at that tonight. There is not much room in the tank compartment and I have foam below, beside, above and behind the tank but the way they make these stupid arfs where the tank neck sticks through a hole in the fuse, that puts all that vibration into the tank. There is not enought room to place the tank farther back and so I might have to bore out the hole in the front of the fuse to issolate it.

Hi John,your symptoms are common with Chinese carbs and it comes due to wrong LSN profile.Let me explain.
 The idling suction of engine is so great that you should put LSN into spray bar some farther to have a good idling and good transition.But that LSN now wouldnt allow spray bar to deliver enough fuel at WOT.Because at full open barrel LSN tip still partly restricts the spray bar so your HSN cant have full control the mixture at WOT because of that restriction.Easy to test.Open LSN some half turn and fly.I bet engine will not stop but you may have stop during low speed flying because of excessive rich idling and mid ranges.(extinguishing the glow plug while giving throttle).
The cure is to change LSN profile to have better restriction at low ranges/idling but fully allow spray bar at WOT.If your LSN has some taper then I recommend to cut up to 1 mm(you may have test cuts smaller that this) from the tip of LSN.This will give a better restriction at low speeds but full allow at WOT.

Dan,

You have missed out on some information about RCU. We are going to vBulletin, so there's no fixing, patching, or whatever. It will be brand new when completed. RCU is owned by Internet Brands and IB is the company that also owns vBulletin. As for those sites you prefer, they have their thing going on and we will have our thing.

I'll give that a try Turk1. I went out and flew today with the other engine (tower hobbies 46) onboard and it flew great. No dead sticks and never missed a beat while flying. It is however a little less power than the 52 I had on it before that I was having problems with but it still takes off the water at half throttle, it just won't go unlimited vertical anymore.

Your symptoms are very common on some engines but not on an ASP 52.ASP 52 has a good carb.
I suggest you a good carb cleaning operation before playing LSN profile.I know ASP 52 engine and they are great.Most probably a dirt is partly restricting your spray bar to deliver enough fuel at WOT when inertia of fuel in tank also resisting to go.BTW did you get remote HSN to carb?If not I strongly recommend you to shift it onto the carb.(I suppose your 52 is an ASP)

Turk1, its not an ASP. I bought it off ebay and the brand of the engine has been milled off. As far as I can see, it looks to be a JBA engine case, carb, and muffler but the head looks slightly different. The engine was new when I got it and it seems to run great on the ground, it just doesn't run great in the air. Here are some pictures of mine, aluminum color, and a JBA blue color. Of course on the blue engine picture they have the carb backwards. The tiger shark 52 engine is also very similar.

That is the badge location. The badges sometimes just come off, or they were never installed in the first place.

If it is a JBA production(which I know them well), probably I was right.Some SK,JBA engines has wrong tapered LSN s.You can have great adjustment on ground but during take off it goes leanest to stop.This comes from inertia,unloading of prop etc.The solution is to cut a little of LSN tip or another way to provide LSN has better restriction as I described above.By the way,those engines are really great if you can do such a work.
Here is a fresh example.This is my Messerschmitt with a JBA 91 ringed.It needed a slight cut at the tip of LSN to prevent similiar symptoms as yours.
[youtube]http://www.youtube.com/watch?v=oWpTJPblnEw[/youtube]

This has definitely been milled off. All the engines of this type I have seen of this type have had the brand cast into the case just like the 52 was cast into the other side. This was cast at one time and then machined off. There are a few engines with identical cases that I have named above and I am sure it came from that factory but I just don't know which one but that is not important. I will figure out how to get it running right even if I need to put on a different carb.

Once J'en engines were JBA made also.