RRY/AJC .65 Stunt Engine

LAST EDITED ON Jan-28-04 AT 08:41 PM (CDT)
 
OK Guys,

I'm going to try the SN article with this, but I wanted to show you the beginning. The casting is made by a friend of my, Andy Coholic. I've made some subtle changes to it for a stunt application. It was designed as a sparkie. My version will boast rear main ball bearing, single piston ring, and timing still being decided on along with some changes to the transfer (bypass port) to accomodate the timing without adding height. The drawings are CAD done by myself, it is a layout I'm using to develop the features I want.

This is gonna' be fun!!

Randy, is that case die cast? I see a seam. Appears to have been cast solid. In another life, I did a lot of lost wax/ceramic shell bronze casting.

Interesting exhaust configuration.

Reminds me of a Taipan .40(?) in Bud Bodzioch's collection. The Taipan only had the exhaust coming out in one place, though.

(Randy, your friend Andy's probably sick of hearing these jokes.. and I really should restrain myself.. but it is a good thing his first name isn't Albert... )

Kelvin,

This is a sand casting and as you've noted, there is no coring. I have already done so pretty extensive surface finishing and reshaping in preparation of blackening the case exterior before I begin machining. In the next step it will be bead blasted and inspected for surface flaws. After I'm satisfied with the finish it will degreased and blasted again then placed in a blackening solution ala Drone Diesel. If and when I get to a point were I make these in multiples I will make new patterns so the case will be unique.

Randy,

This case configuration was inspired by the Edco Skydevil and is called the AJC Skyburner by its designer. I haven't decided what to call my variant. Variant is probably not the right term since I have basically designed an engine that will fit in this modified case.

Iskie,

You're so right!

LAST EDITED ON Jan-29-04 AT 01:33 PM (CDT)
 
>Kelvin,
>
>This is a sand casting and as you've noted, there is no
>coring. I have already done so pretty extensive surface
>finishing and reshaping in preparation of blackening the
>case exterior before I begin machining. In the next step it
>will be bead blasted and inspected for surface flaws. After
>I'm satisfied with the finish it will degreased and blasted
>again then placed in a blackening solution ala Drone Diesel.
>If and when I get to a point were I make these in multiples
>I will make new patterns so the case will be unique.

Randy;

Just curious, but how do you plan on bushing the crankcase? What do you plan to use?

Bob,

The rear will be a ball bearing and the remainder will be in bronze.

I have a lot experence <27yrs> welding casting flaws and have worked with machine shops doing prototype & production commercial and aerospace. I can do precisison build ups if the need arises.this looks like a fun project so mabe i can help. im in CA I also weld ultralite mufflers using .030THK sheet&tube and of course the beads are nice!

Hi 8,

Don't know what you have in mind, but engine restorers usually need welding done, broken lugs and such. I did some of that way back when, but sometimes need a little welding done now and don't have the equipment.

Randy, ref. your No.4 post and reply concerning blackening of your Vivell cylinder. Thanks for the info, in fact I do have a bottle each of the Birchwood Casey steel and ali solutions.
I have not used the steel one yet, but have tried the ali, but not with complete success. Can't get the deep, even, black. I know it's possible, even on mag. castings, because I have seen great work done by a pal, Les Saxby, (who is well advanced in constructing a full size WW1 Nieuport 17, but that's another story). He also makes terrific model engines just like Randy.
I follow the instructions but don't quite get the results. You may have answered the question, - is the trick to immerse the part completely in the solution? If that's it I'd better get a few more bottles.

Hi Ian,

The key to good blackening is that the aluminu, must be clean and free of oxidation. As you may know, aluminum starts to oxidize imediately upon being exposed to the air. Most recommend abrasive blasting of some kind followed by imediate wash and immersion in the solution. The other more frustrating issue is that different alloys react differently to different solutions and the color can range from a deep purple to a slate to a rich black with even some ugly browns along the way. Problem is it takes allot of playing around to find out what works with what. I've decided that I am going to wait on the blackening while I do the prototype work and when I build the final edition I will do all the fancy finish work. Or maybe give it one shot in a solution and blast it back off if I don't like it, but I don't want to waste time when I could be actually building the engine.

Wow, Randy, you sure do work fast! A model airplane is such a simpler thing to build than an engine, but it takes me a year to build one! That's mostly down-time, of course, which is why it takes so long. I have to say, it's a real thrill seeing a project like this from the beginning. It's already a work of art!

Tim

Hi Tim,

Let me debunk a myth. In reality building an airplane is considerably more complex then building an engine and many of the tasks are similar. In addition the parts count in a single cylinder 2 stroke engine is usually between 20&30 while the count in a large profile model is easily 10 times that. Many of the techniques are similar, when we build models we fit each individual part, same with an engine though there is a difference in that the fits in an engine are more precise (and there is no filler to make up for bad fits). In an airplane there are a multitude of alignments and that must be held in relationship one to the others, in an engine there are 2, piston to crankshaft alignment. Basic equipment requirements differ and each require specialised equipment BUT, in both cases the equipment can be basic as long as its good quality. Finishing is much easier on an engine then it is on a model. On the AHC diesel for instance, the case finish was simpley bead blasting and it gives the aluminum a beautiful appearance, 3 minutes work, I spend weeks even months on a stunter. I fully believe that a good model builder with the desire and good effort could very easily learn to build engines. For me its a fascination with making parts out of raw metal shapes and at last hearing it and seeing it produce motive power, or to simple watch it operate, or even just to look at it. Isn't that part of why most of us build model airplanes, all the sticks and sheet parts cut out assembled into an operating airframe, fun to fly but just as much pleasure just looking at it setting on the bench.

Its alot of fun for me, but really, its simply a set of skills learned and applied just like building model airplanes is.

Now designing is a bit different, but anyone with the interest could find the information needed and apply it to produce their own original engine. There is probably more time in designing then in building, but that applies to high performance aircraft as well.

So, thanks for your enthusiastic appreciation of my stuff, but I'm able to do it just because I want to, anyone else could do it as well with the investment of the effort to learn it, just like airplanes.

Randy,

I love to watch your efforts and applaud your building a (prototype) stunt engine.

May I offer a practical suggestion? I wouldn't be able to use this engine because it wouldn't seem to be suited to the use of pipes or mufflers. The trend seems to be toward rear exhaust engines. I prefer rear exhaust engines (even two stroke) because of the ease in installing a home made muffler.

Competition rules require mufflers, and weight is a very serious consideration.

Keep up the good work,

Al,

Thanks for the feedback but let me clarify something here. This engine is not intended as a PA engine, my specific application is for OTS and Classic and the engine is really designed using 1960's technology but with current timing. There is no intention, at least at present, to produce this engine for general sale, this is a personal project for my own enjoyment. I'm sharing it because quite a number of folks have expressed the desire to see it come together. In addition to that, I have no claim to fame, I'm not a particularly good stunt engine designer (or stunt flyer for that matter) so at least for now I have no inovations to add to the state-of-the-art.

I do have intentions however of a couple rear exhaust engines .40 and .60 that I hope to eventually prototype and build, again for my own enjoyment.

None of this rules out a future project to produce low volume runs of an engine of myown design and manufacture should I learn something along the way that would make it more desireable to stunt people then what is currently available. Right now that seems quite unlikely because there are some beautifully designed and built engines available at reasonable prices. Anything I would produce at this time would simply be current state-of-the-art in a different shape, no better mouse-trap here.

Randy,

Sorry about my misunderstanding of your intentions. I guess I was misled by the topic of the thread. RRY/AJC .65 Stunt Engine.

No apology necessary Al, I guess one would need to read all my engine threads to know what was going on. Thanks for your input however, If the time comes when I may be able to actually produce a stunt engine for competitive consumption I'll solicit lots of input on how to make it the most user-friendly possible.

Hi Randy,
Your engine projects have been outstanding!

I have something that might be of interest. It is an origional Orwick case casting (.30+/- size). I believe it might be a reject, because of some voids in the metal. My Dad worked briefly for Orwick and probably picked it up at that time. Since it has some sentimental value, I don't want to finish it or lose it.

Since you have a casting source, perhaps it could be re-created. I've attached pictures but they may not appear since I'm new at this. If it doesn't show, e-mail me direct and I'll send it to you (I tried to do this before, but the mail bounced back).

I would love to see it as a future project.

Norm Furutani
[email protected]

Hi Norm and Thanks,

The Orwicks were really nice engines. So nice that they have been replicated commercially, even these bring a handsome price. I'd really like to build both a .30 and a .60. One of your pictures came out nice but I'd need more then that to work from. The only way to make a casting model of this would be to measure the existing casting and make the shrinkage corrections. If that isn't done, the chances are that while the casting may look nice, it may not be useable because it will be undersized or too thin is some spots. Shrinkage of such a small part is small, but Murphy lives to ruin projects like this.

This part having sentimental value for you should not be mailed around and I doubt you'd want to do that, and I don't think I'd want the responsibility of having it in my hands.

One thing you might be able to do though is to make plaster impressions of it that are split at the original split line. This is done by making the first half and dressing it to the split line, then replacing the the casting in the first half and pouring the second half over it. The casting needs to be waxed well do it will both come out of the plaster easily and well as be protected from getiing plaster in the pores which could cause damage to the metal in the future. The halves also need to be "indexed" to each other so that they can be properly aligned when the model is poured. The resulting piece would then be measured and modeled in wood with the shrinkage allowances. This model would then be used to make the pattern equipment to make the sand molds with. Long draw out process to get there from here, but if you want to make the plaster impressions and they are useable, I might look into doing a Orwick some time in the future.

Randy, it could be that the easy way to get Orwick castings would be to call John McCollum and see if he can sell you a raw casting set. I think he's tired of making replicas, anyway.

Oh, I saw an original EDCO today ($400 asked), apparently in Tether Car (or boat?) form, short shaft, with a flywheel. Would it have still been called the "Skydevil", or would it have been called the "Trackdevil" or "Wavedevil"? Steve

Randy, What i had in in mind to posably help if the need arises are to fix porisity in the casting which you wont know what you have until you start hoging metal out and If you take to much off or you know that murfy guy gets you, I can put the metal back. good luck

Hi 8's,

Good to know you're available, but in this case should there be casting voids the gent that supplied the casting would replace it. Are you interested in doing restoreation work? Broker mount lugs, etc.? I don't have access to a TIG welder anymore and I do restorations that require welding from time to time.

lets put it this way;if its metal i do it. i have $5000 worth of all types of rod ie alum,mag,ti,stainless,inconell,hasteloy,nickel,bronze,brass and many alloys of the above.so to answer your question about fixing old moters i can help you with that.805-526-9074 scott ALLWELD