Hobbsy

My Feedback: (102)

Martin, between you and Earl you gave me a bad case of , "projectitis" I had started this project a year or two ago. It is a Mini Telemaster intended for electric use. Well, you know that's the equivalent of a deadly disease at my house. I used a very small mount to mount the LA .10, you can see how I had to be very careful to not split the ends of the mount. I had to remove the head to get the engine in there and slot the front bottom for the exhaust. I also used an exhaust extension. When I finish the throttle hook up and fuel tank installation it'll be ready to go.

earlwb

That is pretty cool, I like the clever way you side mounted the engine.
I suspect a few people will ask how you got the engine in there at the flying field too.

ebeneezer3

Flight report?

Hobbsy

My Feedback: (102)

That's not the first time I had to disassemble an engine to get it into a plane. When I put my PAW .40 into a Sig Rascal 40 the exhaust collector ring was a problem so I took the cylinder and collector off, rotated and worked the collector into place after first determining where to outlet hole needed to be, then re-assembled. I just discovered that I have a kit of this same plane. Imagine that. Flight report next Monday if its not 100 degrees, my heart Dr. doesn't allow me out in that. Although yesterday I snuck out for a 125 mile Harley ride. Had to break in my new tire.

Hobbsy

My Feedback: (102)

If any of you have considered getting a PSP engine test stand, they have a feature for smallish engines, two such engine that will fit are the LS .10 and TT .10. There are four 2/56 holes in the top of the hold down bars, you need 2/56x.375 bolts because the holes are not drilled clear through, I assume so they will not weaken the bar too much.

spaceworm

That feature for small engines would be great to add to any other other test stand using hold down bars like the PSP. I have several .09, .10, .12, .15 and .19 engines with beam mounts that are two small to clamp in the standard test stand beam clamps. Thanks for the idea.

Sincerely, Richard/Club Saito #635

Hobbsy

My Feedback: (102)

Hey Richard, I rode my Harley down to the field Monday but nobody was there, did anybody fly Monday or was it just too hot. Thanks, Dave

mylamo

My Feedback: (1)

A few years ago I built the Mini Telemaster and powered
it with an MVVS .15D. Mine has flaps and looks like the box
top picture. That was too much engine and now it has a .12
Modela and flies a lot more Telemaster like.
Ralph

spaceworm

Hi Dave,

I was out of town and could not be there. I guess the heat may have been to blame. Good to hear from you. I hope to be back in the air soon.

Sincerely, Richard

Hobbsy

My Feedback: (102)

Good to see you back in circulation, my Dr. doesn't allow out in the heat much so I'll be one of those early fliers.

Ralph, How do you think that little Mini kit would handle a Saito .30? Thanks, Dave

Hobbsy

My Feedback: (102)

I ran the LA .10 conversion for one hour and 10 minutes burning about 5 oz of fuel if that. The picture of it running is at full blat, no smoke. I tried a MA Scimitar 9x5, best rpm was 8,410, next I ran a MA black prop 9x4 it is turning 9,450 in the picture. Also pictured is the piston top and head unretouched plus a paper towel with good colored exhaust residue, don't ask about the blood. 3,000 was about the low limit on idle. Throttle is impressively rheostat like and instantaneous. There is a very fine line between best compression and overcompressed but it is easy to find and repeat.

Hobbsy

My Feedback: (102)

OK, when I was running the LA .10 with the second prop it would suddenly go from about 9,450 up to 10,100. at first blush I thought the sun was playing tricks on my TNC. It never had before though. Upon further inspection of the engine look what I found. I then thought the wristpin had broken but its just fine. Mighty peculiar, this problem does not seem to be Diesel conversion related. The rod to wristpin fit is fine, rod to crankpin fit is fine. The crank can't move back, so what is it. Note shiny place on counter weight. The rod can move back and forth on the wristpin about 1/8th, it obviously moved forward into the counterweight for some reason.

earlwb

Looks like the factory didn't recess the connecting rod to clear the crankweb on the crankshaft. the counterbalance part of the crankweb protrudes towards the connection rod a little, but the rod is straight without having a little machined off to clear the crankweb. The factory probably machined the big end of the rod a little too much for the crankpin so the rod can move in on the crankpin a little too far then. the rods usually have a bit of a "I" shaped profile to them from the side.

I suppose one could run it that way and eventually the rod gets a recess worn in by itself to clear the crankweb. But I would be concerned with it catching on the edge just right and jamming up with spectacular results. Maybe it doesn't happen in real life though, hard to say. when the engine is assembled, and you push in on the connecting rod and then turn the crankshaft, does the rod catch on the edge of the crankweb and jams up? If it does you need to machine something then, if it doesn't and it just barely touches, then maybe do nothing and let it wear in itself. You could machine in a small recess on that part of the rod to alleviate the rubbing or machine a little off the crankshaft crankweb there too, or both even.

You might want to pull the crankshaft out and roll it on the edge of a glass plate or something to ensure it isn't bent slightly too. The factories with their fancy CNC machines, tend to spit parts out and into a catch bin and if a part hits just right it might damage it slightly. Sort of like the the first parts out have the farthest to fall into the bin than parts later on when the catch bin is filling up. With the inexpensive engines the factories may take more cost cutting measures than with a expensive engine.

When they designed the engine, with all the cost cutting they did, this may be a "as designed" kind of a feature, and it doesn't normally cause a problem as the rod will wear in a little there and be OK. Hard to say, since we aren't privy to what the factory or engine designers did with this.

spaceworm

[quote]ORIGINAL: earlwb

Looks like the factory didn't recess the connecting rod to clear the crankweb on the crankshaft. the counterbalance part of the crankweb protrudes towards the connection rod a little, but the rod is straight without having a little machined off to clear the crankweb. ...
/quote]

There is a step/shoulder on the crank pin that appears the same height as the counterweight cutaway step. I imagine that is for clearance to avoid the con rod hitting the web. It may be that wear has allowed the conrod to ride out on the crank pin and permit the conrod hitting the web due to the angularity? Just my casual observations and thoughts. Good luck.

Sincerely, Richard/Club Saito #635

gkamysz

My Feedback: (19)

I think this is a tolerance issue. The rod of the 10 LA doesn't have reliefs to clear the counter weight. The interference is small as can be seen in the photo Dave posted. What happened? I think the tolerances left little clearance between the rod and counterweight. During heat treatment the crank warped and used up what was left of the tolerances. If the grinding wheel used to finish the crank pin isn't square to the crank axis(and it wouldn't necessarily be) then it wouldn't clean up this problem in the grinding process.

If it's still under warranty I'd flush the diesel out and send it back. If not, file a relief and be done with it.

Hobbsy

My Feedback: (102)

I did do a quicky check of the crankshaft and it is straight, I thank you all for the ideas and and will investigate further tomorrow. I have to take Geri to VCU to see a bone specialist. We'll see how much tomorrow is left for playing. Thanks all.

Saturday and Sunday are taken up with a motorcycle ride in to raise money for a 7 year old with brain tumors. We're expecting 400 motorcyclists and maybe more.

Recycled Flyer

Hi Dave,
Inote that you had to remove the head of the engine to do an install into the model and was wondering if this could be the cause of the problem.

I might be grasping at straws here but is it at all possible that when you re installed the head that the torque sequence pulled the liner out of the vertical plane ever so slightly. If the liner could be convinced to lean forward even half a degree it would exhibit the wear pattern shown on the con rod - PAW engines do this if you are not sensitive and aware how to torque down the cylinder jacket properly.
Or can you persuade the liner to sit back further in the block upon reassembly?

Its just that carving out the con rod seems too brutal to me and if a careful reassembly doesn't work then it simply has to be a crank web grind.

Good luck with it mate and with Geri.

Hobbsy

My Feedback: (102)

Thanks RF, I have not run the engine in the plane yet and I'm very careful when installing heads. The liner is a firm slip fit into the block. I torque the head bolts to 5 oz inches. Thanks for the best wishes for Geri. I will vestigate sum more.

AMB

Hobbsy Do not know how much fore and aft play in the shaft if excessive you can prehaps use a brass washer between
the drive plate and crank case maybe thin it down so you have about .005 clearance might solve it did this on one of my PAW

martin

Hobbsy

My Feedback: (102)

Hey Martin, you got your pooter fixed, is it fast now.

The for and aft play is very slight that's one of the first things I checked. I'll dig into it some more though.

AMB

Hobbsy yes new hard drive, file transfer, ram increase $240 and a few other things quick now its a 2003 sony vaio but beats buying a new one.
After what i heard today from the owner of the drug store where I work this is a small issue Llmar the owner flys full size
has an AT-6 Canadian issue called Harvard up there and a similar plane Chinese modeled after the YAK trainer Russian which was their copy of the AT6 Big radial engine on it
One of the mechanics at the Sanford went start it yesterday and guess knows zip about radials
After standing for a while oil will run down into the lower cylinders
Correct procedure with ignition off hand turn the prop slowly a couple of turns in reveres direction
exhaust valves open oil drains out , then procede with normal start


Mechanic justs hits the switch engine now hydro locked with oil in 2 lower cylinders bends rods to pretzels

Llamar is lucky has a spare engine. a few more bucks than doing this with one of our diesels martin

mylamo

My Feedback: (1)

I bet a little Saito would be a blast on the Mini Tele it would
look funny though.
I would look at the crankcase bushing fit on that OS. I think
it is oblong.
Ralph

Mr Cox

The rod might just need a little relief as stated earlier, but the wear pattern is a little odd though. If the crank webb is flat, and true, then the wear pattern on the rod indicates that the rod is not running true, i.e. the crank pin is not true or the rod itself is bent forward. As it is a diesel conversion it kind of hint towards a slightly bent conrod.

You could turn the rod over just to see if that makes a difference and indicates a bent rod or untrue low end bushing (requires the same amount of chamfer on both sides of the lower end on the rod).

gkamysz

My Feedback: (19)

A rod that isn't square is also a possibility. It would seem that if the little end was angled forward the big end would likely rub the back plate. I supposed that as long as the bores were parallel there might not be any force that would push the rod fore or aft. Unfortunately, the rod itself isn't available as a spare.

PAW cylinders are very different in design. That will not happen to the OS.

I don't buy new PC's. My newest PC is a three year old HP workstation. Replacing an older used HP workstation I purchased a couple years ago. While not ideal for really demanding software, I'm not a gamer and my CAD software is on a similarly equipped machine already. The most taxing thing I do now is video processing, and my older machine was slow churning through 1080 video. So for what ended up being 180USD I got a dual processor, dual core 2.6GHz, 8GB ram, 1GB GTX280 video computer.