Charles Mackey Snowbird -- Engine choice

[Frank Wadle]

Hello everyone,

I am considering to build a classic ship named Snowbird, designed by Charles Mackey in 1963.
I came across the plan here:
http://www.outerzone.co.uk/plan_details.asp?ID=50
I love the shape of the plane. To me this is one of the most beautiful ships of this era.

Unfortunately I don't know much about it and all the German experts I talked to never even heard about it.
My biggest question is, what engine (IC only) would you suggest?
I think the original was powered by a small diesel. But I tend to use a modern glow engine, maybe a OS-LA25???
Has anyone ever build this plane or has seen one fly?
I'm also curious if it is a good performer?

Any input is welcome :-)

Thank you very much

Frank Wadle

[Mike Anderson]

The Snowbird plan was re-drawn by Ian Smith - it appears in Flying Models Dec. 2006 edition according to
the FM Plans Directory.  Doesn't say if there is a complete article or not.

"Designer: Mackey, Charles
Engine: .25-.32 2-stroke
Span: 57"
Issue: 12/06

Remarks: Construction done by Ian W. Smith for this article. Weighs 41 ounces. Flies using .015 diameter line, 55 feet long. Plans on 1 sheet."

[Dan McEntee]

  I'm thinking I have seen photos of one at a recent VSC, but can't remember details. Jim Lee built a similar looking model that was published but was smaller and a .15 size airplane with a OS FP.15 in it I believe. If you have a fresh LA.25 I would think that would suffice, but if you could find an OS.32 I would opt for that just for the power reserve. I'll have to dig that one out and check into it further. I do like the elliptical wing.
  Type at you later,
   Dan McEntee

[Phil Spillman]

I agree with Dan but would also throw the Brodak .25 into the mix! I've had many happy flights with the B-.25 on: Super Clown with flaps, Barnstormer without flaps, Sterling Mustangs with flaps and plan to put one on my Sterling Yak-9 once finished. These engines perform quite well with 9X 4,% and 10 X 4,& 5 props! Both wooden and glass filled varieties perform well!

[Frank Wadle]

I printed out the plan...
The LA25 just barely fits the fuselage.
I think the original was flown with a rather small engine.
What I'm searching for is something small, light and powerful. Oh, and affordable and available in stores today.
Brodak 25 sounds like a good option.
What else is on the market?
And what are your thought on this plane? Will it be a good performer?

Frank

[Robert Zambelli]

Frank.
I built the Mackey Starlight a few years back and as you can see, it's quite similar to the Snowbird.
The Starlight flies beautifully with a stock Fox 35 and the Snowbird, with a thicker airfoil should fly even better.

I would suggest the Fox - I have some Brodak 25s and although fine engines, I don't think it would be the right choice for the Starlight, even at 34 ounces (what mine weighs)
I would think the Snowbird would be similar.

BUT, why not contact Charles Mackey himself? He's a great guy and I'm sure he'd be the one to talk to regarding power.

The first picture shows Jean holding my Starlight, the second picture is Charles's wife Birdella holding the original plane.

Bob Z.

[Steve Helmick]

I'm going to side with Bob Z. on this one. The plan & info said 57" span and 501 sq. inches...too much for a .25 for most of us. You really don't want "not enough" umph in the nose. If you like Fox .35's and 25%+ castor oil fuel isn't a problem, it's perfect. And I kinda like the Starlight better than the Snowbird, FWIW...the single piece elevator isn't as 'cool', IMO.

Personally, I'd throw a Magnum XLS .36 in it and stretch the LG (and tail strut) enough to use an 11" prop. The XLS .36 isn't made anymore, but the APS .36 is, and it's the same engine. I think you could get one from Hobby King pretty inexpensively. Various aftermarket mufflers (Fox .35 or OS .40FP/LA bolt pattern works) are available, and the stock muffler isn't horribly heavy. The engine is relatively compact and light for a .36 with twin bb's...see pic. The inexpensive TT Cyclone 11 x 4.5 is excellent on this engine.  Steve

[Frank Wadle]

What engine was originally used in the snowbird?

I would love to use one of the mentioned .36 size engines, but I'm afraid they are to heavy (300g). Thats's why I was looking at the LA25 (185g).
Also crankcase size is critical. The fuselage is very small and stretching it to a 40 size engine might ruin the sleek look. The LA25 just barely fits if I use a 0.5" shaft extension.
Some people here in Germany suggested the LA25 and a big venturi and lots of nitro...
I really don't want to have a lack of power, so what I need is something similar in size and weigh to the LA25 but with more displacement and power.
How does the Brodak.25 compare to the LA25?

Frank

[Robert Zambelli]

Hi, Frank.
As Steve mentioned, the 36 would probably be an ideal engine in terms of power but, as mentioned, it is heavy.
Note the long nose moments on both planes. Mine was noseheavy with the Fox 35 but I was able to trim it out by going to a plastic spinner and wooden prop.
Charles mentioned that the Starlight should be fairly light for good performance. I would imagine that applies to the Snowbird as well. A heavy engine plus the amount of weight needed for balance would increase the mass moment to where the plane could be sluggish.
Why not look for a good Fox 35? I have seen them sell on eBay for as little as $15.00 USD and as high as $45.00 for brand new examples.
And, for what it's worth, I still do not believe that the .25 engines will supply sufficient power. You might compare the mounting footprint of the Fox to that of the 25s and find that they are quite close.
I have done some comparative testing on the Brodak, LA and FP 25s and found them relatively close in performance. As I recall, the Brodak was the lightest by a small amount.
I hope this information helps.
Bob Z.

[Frank Wadle]

Yes, the Fox35 is an alternative. It is light and compact.
How would you operate it? In a 4-2-4 mode or with a High-Low (High RPM, Low pitch) Setup at a constant 2cycle?
I'm asking as I always found the Fox35 rather weak (Low power) when run in 4-2-4 mode.

Another alternative that just came to my mind would be a strong F2D engine with a 8x3 prop at 20,000+ Rpm... Not sure if that would give enough power, but it would be very light and compact.

BTW
Higher prized engines are an option too. I just want something that can be purchased new, not a collector's item.... So what about RoJett?

[Steve Thomas]

d a big venturi and lots of nitro...
I really don't want to have a lack of power, so what I need is something similar in size and weigh to the LA25 but with more displacement and power.

Enya's SS30 might do nicely. 195g, plenty of power, and a really good 'wet 2' run with something like an APC 10.5x4.5.

[Frank Wadle]

Thanks Steve, that is a good suggestion!
And as so often, while searching for the SS30 online I found something very promissing
ENYA 32 CXS-PRO  (5,23 cc)  SIDE EX
or
ENYA 32 CXLS-PRO  (5,23 cc) REAR EX

Seems they are made using the 21 size crankcase.
Has anyone had one of them?

A picture can be found here:
http://www.clubtamaran.com/ENYA.htm

I like the Idea of a rear exhaust engine. All my F2B planes use Rearexhaust engines.
It just looks nicer AND it brings the CG a bit back.

[Robert Zambelli]

Frank: What Steve said makes sense.
I've been using ENYA engines since the early 60s and I'm quite pleased with them.
I'm not familiar with the newer ENYAs but if they're anything like the older ones, they're an excellent product. Just be patient on run-in!
If the 32 will fit, it should be worth a try.
But, keep the Fox 35 on the back burner.
No matter what anyone says, it's a fine powerplant and properly set up, it will hold its own and handle most classic planes. Just check the records!

I can't comment on the Snowbird but the original Starlight flew with a Fox 35.
It was run is a fast four-cycle.
It weighed 46 ounces and was flown on 69 x .015 cables.

I have the original Starlight article from Flying Models, August 1967.

If anyone is interested, I will gladly scan and post it.

Bob Z.

[Tim Wescott]

Some people here in Germany suggested the LA25 and a big venturi and lots of nitro...

You need to look around and find one of Brett Buck's rants about power being used vs. power available.  You want an engine that will loaf along in level flight, but will deliver more power when it's loaded down, all without running away.  I suspect that while an LA 25 with a too-big venturi may provide lots of power, it won't do so when you actually need it.

[Tim Wescott]

This is kind of a wacky suggestion, but see if you can fit an LA 25 with a pipe into that airframe.  Dirty Dan Rutherford was flying 500 square-inch "wimpact" profiles with piped engines (either FP-20 or mumble-mumble-25), and doing quite well with them.

Not only should the pipe work well with an LA 25, but it'll certainly help with your CG issues.

[Mark Scarborough]

I am not so sure that an FP 25 would be lacking,, this is not a big airplane,, and its fairly clean,, thinner wing( as compared to modern airfoils) and built light I see no reason an FP or even a Newer generation LA 25 would be lacking,,
The pipe helps regulate the power delivery,, but its not there for power generation,, as such
You may try looking up Dirty Dans whimpact thread,, I seem to recall it was mid 500 inches and with a nice fat airfoil

[Frank Wadle]

Thanks everyone!
I think I'll go either for a LA25 or, more likely, for the Enya SS30.
The FOX35 is not exactly my "kind" of engine, neither are pipe setups my favorite...


One question remains unanswered:
I'm very curious what Charles Mackey used in his original Snowbird???

[Keith Renecle]

Hi Frank,

I was hoping to see you again in Poland, but I know that you could not make it. I see you in photo's from Claudia Kehnen at the German Nats this last week-end. Looks like you are doing very well in stunt these days, so well done. I love your big "see-through" stunter!

I can only agree with Chris about the Enya SS30. I used to sell Enya over here and that particular engine is a great replacement for a Fox 35. It weighs about the same and the standard silencer is also very light and compact, so I would think that it is a good choice for the Snowbird. If you need to send an e-mail to Charles Mackey, then I know that Eric Rule at RSM Distribution has contact with him, so drop Eric an e-mail and I'm sure that he will help you. Eric is on this forum so you can send him a personal message. Be sure to post some photos when you get going on the Snowbird.

Keith R

[Steve Helmick]

Thanks everyone!
I think I'll go either for a LA25 or, more likely, for the Enya SS30.
The FOX35 is not exactly my "kind" of engine, neither are pipe setups my favorite...


One question remains unanswered:
I'm very curious what Charles Mackey used in his original Snowbird???

While I can't say that I've read all of Mackey's magazine articles, the ones I recall reading at least claimed to be Fox .35 powered...Gobbleswantz, Lark, bf-109 (being accurate just for Mr. Scarborough!), Spitfire and some others. Well, there was the Mackey Profile, which I seem to recall used an Oliver Tiger or something of the sort. What was not said in a lot of those articles was that the Fox engines were usually well fitted and often run on 15%-25% nitro. What needs to be said now is that the crankshafts don't hold up nearly well enough to run either a high rpm 2-2-2 run, or lots of nitro, or any sort of heavy propeller. A modest increase in 4-2-4 rpm is a reasonable approach, with 5" pitch and 10% nitro, but you'd still be stuck with a greasy aeroplane after each flight!

The Enya .30SS suggested sounds like an excellent choice. It should easily put out more thrust than a Fox .35S and hold up much better.    Steve

[Mark Scarborough]

pretty sure the snowbird was powered by a small diesel,,
I am pretty sure it was not a fox 35,, but then,, I could be mistaken,, I read this article many times,, I love the look of that plane,, its just small,,

I like stuff a bit bigger personally,,
that said,, thanks for accuracy there Steve,, you even got the lower case bf correct,,

[Paul Allen]

Hi Frank
           Mark was right ,in Ian's article on the Snowbird, he comments that the Mackey model was
powered by an Oliver Tiger 2.5cc diesel,he also comment that he used a Royal 28 in his model.
I can tell you its a good flying model having flown against it in a local Classic comp a number of years
ago.
Paul
In Oz

[Frank Wadle]

Thanks everybody for your help!

Last weekend I made my choice.
I went to a Model Airplane flea market last Saturday and one of the vendors had ENYA engines for sale... brand new in box with guarantee...
And believe it or not, he had a SS30S for sale that I bought right away. A lucky find as CL-engines are a rare thing on such markets.

Placing the engine on the plan show that it will fit just nicely (with a shaft extension and a few millimeters extra fuselage width).
Now I just have to finish my F2B project this winter and find some time to build the Snowbird.. Wish me luck! :-)

Frank