engines

hi I was just wondering how you guys find a suitable engine when building a replica.
Do you guys try and source an original engine or build the engine from scratch or are there companies which build replica engines especially for replicas?
I've heard that the guys that build the WWI fighter collection in NewZealand are building there own engines.

[greatwarpilot]

Well I can't speak for everyone, but at least in my organization we haven't put a lot of effort into looking for original engines. We regularly fly our fleet cross country for air show performances and as a result we've opted to go with slightly more modern engines.

To replace the rotaries we've used assorted radials, all with more horsepower than the original rotaries. Examples from our fleet include the Warner Scarab on a DR1 (165hp), a Jacobs (235hp I believe) on the second DR1, the Continental W670 / 670-9a (220 and 250 hp respectively) on our N28 and Sopwith 1 1/2 Strutter, and the M14 (360hp) on our Camel.

For the originals that had inline engines we have replaced them with more modern in lines with the same horsepower. Our SE5 and Fokker DVII are both powered by Fairchild Rangers (200hp).

Now as to the logic behind these choices I think it depends on what you want to achieve with your replica. If you're looking for an aircraft that is as close to the original as possible, then an original engine is the way to go. If that’s not practical either because of the way you want to operate the airplane or because of the cost or difficulty of finding one then I think the idea is to get a similar modern substitute.

Be it a radial or an inline I'd say the objectives are to find something similar in physical size, weight and equivalent in power. Size is important so it will fit inside an original cowling and not change the looks or aerodynamics of the airplane. Weight is important so the airplane will fly as close to the original as possible from a weight and balance perspective (as an example the Ranger weights much less than the Mercedes that was originally in the DVII, so many builders either lengthen the nose, or add weight to it to compensate when using the ranger). Finally an equivalent amount of power is probably the most important, but hardest to get right. While a ranger may have 200 hp, it is designed to turn a small propeller at high RPM. As a result it doesn't give the airplane the same performance that Mercedes or Hisso did when turning a large prop more slowly.

I can't speak to the details of any group that is building their own engines, but I have heard that it’s happening also. Perhaps another fourmite can enlighten us as to the details.

[Mark]

I thought I would bring this oone to the top rather than start a new query, but does anyone know of any attempts to build a full size rotary in recent history?

I have the scale Clerget 9B book, but was wondering if there hae been any attempts on a full size engine anywhere?

[franzkait]

Mark,why do you like to know this ?

[Mark]

Uh Oh, am I opening a can of worms here?

At any rate, in answer to your question I was curious since there is are couple generations of pilots now who would be curious to see how a plane would handle with that rotating mass up front. Plus, I think everything else being equal it would be pretty cool.

A few years ago I drew up preliminary design plans for a supercharged, two stroke rotary but life and children kinda put it on hiatus. I was thinking on the lines of retaining the rotary concept but otherwise using current technology, more from a reliability standpoint than performance. Direct drive of course.

At any rate, I was just wondering if others have had any experiences or knowledge in this area.

Mark

PS- I am writing this before heading out the door for a fun filled week at the in-laws so it may take a while for me to respond to anything, so I'll be sporadic until the 31st or so.

[franzkait]

Mark,a supercharged two stroke rotary is not really new. For example, Ajax and Wagner. I think the Wagner was still in production in 1960. The main problem about new rotarys , there is always this big talking about it ,but if it comes to talk about money it is very silence

[Mark]

Franzkait,

Thanks for the replies, I did not know about either the Ajax or the Wagner. I'll try to do some research on them whenI get back home (I'm writing this about 325 miles north from where I posted this AM).

Not only do I not care about trying something new, I'd prefer to not reinvent the wheel if someone has already been there before. What I would also like to do is utilize existing components much as possible rather than do everything from scratch if I were to decide to actually create something like this. Since I saw the post on engines I thought I'd piggyback on to it. The actual "doing it" part should be pretty simple, I'm a certified master machinist and a certified master mechanic so as you mentioned all it would take is just a bunch of time and money <G>. I have a few years still since my kids are relatively young and I prefer to spend my time with them, but when they get old enough to do stuff in the shop this would be a memorable project to do together.

Your demeanor sounds a little more experienced than the average bear, would you have any more thoughts or comments you'd like to share?

Mark

[franzkait]

research the wagner can be a problem, but try. This 2 stroke rotary was only used in helicopters. Tell me one existing component you can use ? You must not reinvent the weel, just copy a good original rotary like the siemens or the late Oberursel, or better the mercedes rotary. Do you know how many people did start in the last 25 years to build a rotary ?

[jumpinjan]

Originally Posted by Mark

...I drew up preliminary design plans for a supercharged, two stroke rotary ...

So was this just a "hobby" engine to build for fun? You weren't thinking about actually swinging a full size prop with this....were you? Very confusing

[Mark]

Put that way, I would have to define it as being a hobby engine. At the very least I'd want the first design to be under 2 liters just to make sure everything worked! And a good chance an initial engine might be 800CC or smaller.

I've built steam and sterling engines but never an internal combustion engine, and so if I'm going to do one why not go whole hog and try to design one too? And if I'm going to go through all that effort, why not do a rotary? <G>.

Once I've done all that, then I can fiddle around and figure out where to take it next- either to the dumpster or decide to go a little bigger for a scale replica, or try drawing up something that can pull a full sized airplane around. However, I have a lot of time, effort, and $$$ to invest before I get to making that decision. I've found if you don't approach it that way all I would be able to do is land on Mr. Franzkaits list of yet another full sized rotary project started and not finished.

Of course I'm sure I am not alone with these observations, especially on this forum!

Mark