ebay Beechcraft Staggerwing project arrives today

Bob, nice, your explanation clarifies an earlier Scientific Musciano kit build, back in its day would have been a show stopper. Love the way the original owner Indian inked the left door edges and window.

I think I still have an old Indian ink drafting set somewhere with pen and with ink top protractor circle arc drawer. Did India ink outlines on my planes in high school. It worked very well on an orange Esaki tissue Guillow 18" Fokker DVIII razor wing parasol, outlined the ailerons, elevator and rudder moving surface breaks.

Nowadays we cheat and use a permanent skinny tip marker.

If your going to take the OK apart, don't unscrew that cylinder until you free the piston thoroughly first. If you twist the cylinder to unscrew it, you will twist the rod immediately or break it. There's no ball socket like a Cox to enable the cylinder to spin off. The older OK Cubs such as what you have which is the first version used a magnesium backplate. They're usually very corroded and will crumble and break if you don't heat it and have the right tool to loosen it.

Ken Cook wrote:If your going to take the OK apart, don't unscrew that cylinder until you free the piston thoroughly first. If you twist the cylinder to unscrew it, you will twist the rod immediately or break it. There's no ball socket like a Cox to enable the cylinder to spin off. The older OK Cubs such as what you have which is the first version used a magnesium backplate. They're usually very corroded and will crumble and break if you don't heat it and have the right tool to loosen it.

Thanks for reminding me Ken.  Maybe tomorrow I can get to it  but the majority of my days are taken up doing this.

Glad it got there safe , are you making a fly field there ?

getback wrote:Glad it got there safe , are you making a fly field there ?

I'm making a big mud puddle Eric.  Got the tractor stuck this morning right up to the axles down by the pond trying to pull another log out.  I tried to pull it out with the ATV, no go.  Called my son to come over with his 4W drive pickup truck.  He didn't need it, instead he used the bucket to pull it's self out a little at a time by walking it forward.  Drop the bucket with the teeth digging into the soil, pull the bucket back pulling the tractor forward, about five evolutions got it out.

Got the rusty metal cowl off. Rusty #2 wood screws not machine screws holding the engine on. 

Looks like the PO swabbed on either epoxy or Ambroid.  I'm thing Ambroid.  Coated the mount and the mounting screws, had to chip it off.  




The engine was stiff but free when I got it.  A little Marvel Mystery Oil in all the ports was all it needed.




I think all it needs is an overnight soak in 91% alcohol.  Going to sandblast the cowl, maybe paint, maybe not.  I don't want it to look too good as the rest of the plane stays as is.  




So, where is the fuel filler and vent.......................

Bob, engine looks a bit larger, is it an OK Cub .074?

GallopingGhostler wrote:Bob, engine looks a bit larger, is it an OK Cub .074?

Could be George. I have a bunch of OK Cub engines and the only ones marked with displacement are the .099's. The rest have different markings most Pat. #, and OK on the bearers and "Cub".

The closest one to the Beech is this one. Marked the same but has 3 on the forward end of the case vice 2.




Seems on the .049's and .074's they only marked the containers. The .074 a bored out .049?

rsv1cox wrote:

GallopingGhostler wrote:Bob, engine looks a bit larger, is it an OK Cub .074?

Could be George.  I have a bunch of OK Cub engines and the only ones marked with displacement are the .099's.  The rest have different markings most Pat. #,  and OK on the bearers and "Cub".

The closest one to the Beech is this one.  Marked the same but has 3 on the forward end of the case vice 2.  



Seems on the .049's and .074's they only marked the containers.  The .074 a bored out .049?

Bob, I looked onto Sceptre Flight engine site, and although he has done an excellent job in maintaining the best engine article archive out there, but unfortunately lacks in depth articles to further discriminate the OK's (goes to show these were not loved as well as the Cox?), so I went to Adrian's:
Adrian's Model Engines: OK Cubs - early models
His photos seem to confirm that you may have the rarer .074 OK Cub. Also, according to his engine test chart, seems the .074 was about equivalent in power to the Cox .049 Black Widow with its standard head. Given that a bipe would have more drag due to its frontal profile and wing area (wetted surface) IMO, a more powerful engine than the OK .049 would be necessary for decent flight.


Photo from Adrian's Model Engines website.

Adrian also has performance figures and specs on the OKs, so that one if they desire can see powerwise how they compared, or to match to a proper airframe.

A neat subject to restore Bob, Interesting from a historical standpoint….. Also interesting to see experiences and memories from forum members that might have had something to do with a particular model and/or the engine….I’ve got a couple of Cubs I bench run from time to time, An .049A and a .039…. They work and are fun to play with but they really make me appreciate how easy a Cox starts…

Thanks George for digging deeper into the Ok Cub.

I found a few more Cubs, among them is this NIB .074 when compared against the .049 is noticably larger. But, I'm afraid the one that came on the Beech is a .049.  





The NIP .049's are strange, same markings, different designators.  Notice the "Spinner" on the left engine, the one without the prop..  Maybe the reason for the different alpha designator? H and B in this case.



And Robert, I have had good luck with Ok engines using Cox 25%.  I have played around with them a bit.

Bob, your forensics on your Cub engines certainly shares light. I feel like we are in an episode of "Raiders of the Lost Ark". It would show then that an early cast tank was available for the .049 as it was for the .074.

I've been wondering if I replaced the quirky OK NVA with say, a Cox NVA, maybe I could turn mine into a decent runner?

Bob Mattes Engine Rework has some pictures on it of some of the rework he does on the O.K. Cubs. He also has a Nelson head I believe, (not positive). He said not to push them past 18000 RPM or they may come apart.
                                                Mike1484

GallopingGhostler wrote:Bob, your forensics on your Cub engines certainly shares light. I feel like we are in an episode of "Raiders of the Lost Ark".   It would show then that an early cast tank was available for the .049 as it was for the .074.

I've been wondering if I replaced the quirky OK NVA with say, a Cox NVA, maybe I could turn mine into a decent runner?

The early .049 & .074 used the same crankcase, so the original cast fuel tank fitted either.

More fun with the Beech Ok Cub.

This lump is the needle, typical blunt end on these Ok's..



The handle must have broken off and he replaced it by fashioning a wire and cutting slots in the knurled part, then secured with thread saturated with epoxy/CA/Ambroid?  I wire wheeled most of it off leaving some of the thread/cement mix.  Keeping it original or trying.




Actually not a bad job.

This guy was a marvel with wire and thread. More on that later.

Wow, Bob, a mummyfied needle.    Your forensics brings things out of the old Roman catecombs.

Interesting fact on the OK .049 and .074 that I didn't even know, Rod, thanks for bringing that to light.

Mike1484 wrote:Bob Mattes Engine Rework has some pictures on it of some of the rework he does on the O.K. Cubs. He also has a Nelson head I believe, (not positive). He said not to push them past 18000 RPM or they may come apart.

Mike you share some info on Cubs that I didn't know someone as of late is still doing OK Cub work.

Just looking at the various horsepower/torque curves, I got the impression that these peak out HP wise at a lower RPM around say 12,000 - 13,000 RPM, with the standard glow plug heads. Just like the Enya cross scavenge engines, one props them a little differently to take advantage thereof.

Impression from the curves, my OK Cub .059 reed valve, one would not go with say a 6x3 prop, which according to Peter Chinn's and HL Warren were nominally optimal for the Golden Bee, Black Widow, and other .049 Cox reedies.

According to:
Adrian's: OK Cub Reed Valve Models

He recommends against higher compression heads, because the engine as constructed performed poorly, problem with predetonation ignition with the glowdhead element.

As mechanically designed and constructed, they were not made to perform at the higher speeds we expect with other half-A's.

One of these days when I go back to half-A C/L flying, would like to give the Cub's a shot. The .059 I have, would like to see how it performs on 6x4 and 7x2 props.

So, no-one has thoughts about the fueling tube or vent? Previous photos provide a hint, or did they?

rsv1cox wrote:So, no-one has thoughts about the fueling tube or vent?  Previous photos provide a hint, or did they?

Beats me!!

With the Beechcraft's pickup tube exiting out of the left side of the cowl makes me think that the tank used sitting just behind the engine bulkhead is probably a free flight rectangular with the pickup end in the lower right of the tank, transversing catercorner to the upper left side. As to where the fill and vent are, these aren't visible anywhere?

rsv1cox wrote:And Robert, I have had good luck with Ok engines using Cox 25%.  I have played around with them a bit.

I probably just need to get more used to handing them, Others have had good luck…. I know they like a very healthy prime for cold start!

GallopingGhostler wrote:I've been wondering if I replaced the quirky OK NVA with say, a Cox NVA, maybe I could turn mine into a decent runner?

You bet George, I did it on the .039 and works great ….  Installed with a little JB Weld for security….

I've swapped out the OK needle for a Cox spraybar and needle. In truth, it really doesn't do much as far as performance. Don't get me wrong, it works better than the stock unit but I've also found it to vibrate a bit. Use the black nylon piece on the needle to assist in supporting it. It really does help to trim the Cox needle length down even though it places your fingers close to the prop. I don't grab a OK needle, I stick my finger up from the bottom or top and roll it. My biggest complaint with the OK needle is when you open it, it can go from moderately rich to lean and vice versa. Generally, once you find it's setting, it maintains it. Bob Matte went through a lot of work to make these run essentially with Black Widow performance. In free flight, the engines were only running for less than a minute. One thing about the OK .049's-.074's is that you can offer them a fair amount of nitro due to their lower compression. I've really turned into quite a OK fan myself. Unfortunately, it takes a few to get some good runners but they really can be reliable. I've found them to work in terms of weight, starting and offering just enough power for many of my free flight models.

             I have collected many of the larger OK engines even though I don't consider myself a collector. I really like the .29's -.35's from the mid 50's, in addition, I'm a huge OK Super .60 ignition fan. The Mohawk series are also in my opinion some of the nicest looking engines that were available. I love them. They look attractive and sound terrific. They offer very little power but they're very nostalgic for me.

Oldenginerod wrote:

rsv1cox wrote:So, no-one has thoughts about the fueling tube or vent?  Previous photos provide a hint, or did they?

Beats me!!

Other than the fuel line to the engine these are the only other openings to the fuselage.  Music wire probes go about an inch and a half in to a full stop.  





Small opening I thought for a mini hex wrench but no.  Plastic or rubber plug that will not come out.  I'm thinking left side filler with a syringe, right side vent.  Or?  

I cleaned up the firewall.  

PO had painted the whole thing with something then stuck the engine on while wet, then painted the stuff over the mounts and mounting screws.  -  What are you people doing to my model airplanes out there.  

Bob, in cases like this, you may have to remove portions of the planking to expose the tank. Then re-plumb the tank fill and vent. Worst case, if tanked improperly or wrong tank, redo tank installation, then button up. Those are my thoughts. On a positive note, then you can refinish the plane and clean up its looks.