Ohrndorf 5 Cylinder Radial

[petertha]

The fuel tank is just a regular RC style held in a cradle, but I can locate it up or down if that affects running. Generally, tank center should be about in-line with carb & it should pull full to empty without going lean. If its positioned high it can provide a bit of head but also risks fuel free flowing into carb & flooding. I made a makeshift throttle arm with a pinch clamp. I’m not sure what carb type will end up on the engine, so keeping things simple for now.

[Admiral_dk]

Not much room to operate the Needle - but other than that - I love the whole setup 

Plus it is a nice display stand too 

Per

[petertha]

Yes the OS carb came from a more modern 2-stroke principally based on desired orifice size. And well, they make nice carbs. OS now angles the needle valve adjuster axis back away from propeller proximity in order to better maintain finger tips to their stock length. But mounted in my orientation it faces forward  no getting around it. Its only slightly awkward but I can reach it. I think its a result of originally anticipating 1/4" thick firewall but changed to 3/8" on the fly. I can easily modify the carb adapter fitting.

[petertha]

Apologies for my posting lapse again. Well, the day finally arrived with the realization that I somehow had come to the bottom of my seemingly endless To-Do list. There was nothing left to make. After <ahem> ‘a number of years’ it’s a rather weird feeling.

My preference was to attempt a run up in the back yard, fully expecting a multitude of unforeseen teething pains, requiring access to tools etc. But I don’t think my neighbors would appreciate the unmuffled noise (assuming there would be any noise). I decided to take the engine to my local flying club where we still have a heavy, oil-soaked run-up table from yesteryear. It doesn’t see much action these days, but it was a simple matter of screwing my test stand to it. I mentally prepared myself that this was probably going to be the first of many road trips over the summer to get it going.

I have collected a few different carbs & have machined adapter plates so they could be swapped to the back of the manifold. But once the engine was mounted to the firewall pillars & the ignition wires were routed & throttle control hooked up, swapping out carbs was not going to be as quick as I anticipated. So, I decided to go with the O.S. carb first. It has the smaller orifice size & what I consider nice mixture control features, so hopefully that would assist early running attempts which was the prime objective for now.

I felt that hand starting (propeller flipping) a new, shop made, relatively unknown engine was probably wishful thinking on my part. I blew the cobwebs off my old RC Sullivan starter, which has not seen an engine for a dozen years, but discovered the NiMH cells were in bad shape. I could not trickle charge them back to life & had no spares. I could have retrofitted a Lipo or wired it to my 12V deep cycle battery, but I figured probably just as well because the silicone spinner cone was not a good profile match to my smallish prop nut. But mostly I was apprehensive about its relatively high torque & RPM. Should the lower cylinders become flooded, or any internal parts became loose, a strong starter would probably inflict more damage. So, I made a makeshift drive dog accessory to use in my 18v cordless drill. Basically, a hub with short pegs to engage either side of the prop near the root & a center hole to allow the prop nut to protrude into. It wasn’t pretty but I thought good enough for now. The drill is a typical planetary reduction drive so lower RPM. It also has a variable clutch setting so I could utilize that as a bit of safety release. More on this later.

I turned it over by hand choking the carb until I could see fuel flow in the line. I put a few drops of fuel directly into the top cylinder glow plug hole, set the throttle to 1/3, turned all the ignition plugs on & commenced turning it over with the drill. Imagine my astonishment when it barked to life! I think I just stared at it for a while not quite believing what was happening. It sounded a bit rough & choppy but all 5 cylinders were firing. I lowered the throttle a bit to where it ran OK but not wanting to quit. The needle valve seemed insensitive but I could see the exhaust was oil wet & I was happy to let it run rich that way for a while. After about a minute I shut it down. Nothing seemed hot. No parts were sticking out of the side of the crankcase. I decided to grab my iPhone & record the happy occasion.

Now I must confess, this monumental day occurred earlier this summer. I thought I would subsequently figure out how to get a YouTube channel to post a video link, but time commitments got the better of me. So you will have to accept these video stills for now & use your imagination of the sound. I pledge that I didn't Photoshop a blurred prop in motion haha. I have subsequently had the engine apart for inspection & modifications a few times, so will document a bit of that now. It is running better each session. I was just about to give it another go these past weeks but the winter white stuff appeared, so I will have to wait for a better day.

[Roger B]

Excellent   

I'm looking foreword to seeing/hearing the video 

[Admiral_dk]

First a BIG Congratulations - you have a runner  - that must have felt very special 

Would love to have seeing/heard the Video - but it can wait until you're ready ....

Per       

[RReid]

Outstanding! Getting a start on the first try - also outstanding! Congratulations!!
The finished engine looks great as well. A very nice job all around.

[crueby]

Incredible work!  Sounds great in my head, hoping to hear it for real soon!   

[Kim]

Congratulations!  That's so exciting to see your engine run for the first time! 

Kim

[petertha]

This might be in bad taste on maybe contravening forum rules, but I was able to utilize a video direct upload feature on the other forum (post #298). It may take me a while to sort out becoming a YouTuber or exploring other video hosting options. It took me long enough to figure out how to edit the rudimentary clip, but I'm slowly dragging myself into the modern era.

https://www.homemodelenginemachinist.com/threads/ohrndorf-5-cylinder-radial.32844/page-15

[crueby]

I took a look using that link, and even after wading  through screenfuls of horrible ads, I  couldn't  see your running video there.

[Kim]

I did find the video eventually - way down, close(ish) to the bottom of the page.  Lots of adds though

It was a great run!  I can see why you are pleased, you should be!   

Kim

[crueby]

I did find the video eventually - way down, close(ish) to the bottom of the page.  Lots of adds though

It was a great run!  I can see why you are pleased, you should be! 

Kim

Were you logged in there? I was not, found the post where it said heres a video  but it didn't  show. Great reminder of why I  stopped posting there, horrible load of ads.

[RReid]

I imported the video into my own youtube account, and post it here. I hope you don't mind, petertha! I did not make it public, only "unlisted", so only those with the link can view it.
<a href="https://www.youtube.com/watch?v=Imz5YBPUymQ" target="_blank">http://www.youtube.com/watch?v=Imz5YBPUymQ</a>

[crueby]

Thats awesome!!