mahalalel

I am contemplating scratch building a Westland Whirlwind. Whilst not my first scratch built aircraft it will be my first twin. I have been reading most of the topics about flying/building twins but would like some advice specifically on the whirlwind and my mad ramblings about dimensions.

I intend using .46 cu in motors and have based the starting size of wing on the wing area of the Pica Duellist. It seems that everybody agrees it is a good flying model if built lightly. The wing on the Whirlwind has a fairly high aspect ratio. To match the duelist's 67 in span, 795 sq in wing area the whirlwind would have a 78 inch span for a 799 sq in area. I will build light and monocote.

Specifically my concerns are:

11 inches extra span, more weight, can anybody guesstimate how much?
Would the gain require more power due to weight?
The engine thrust lines would be 11.57 in from the fus centreline - how does this compare with the duellist?
What area is the duellist's vert stab?

I am cognisant of the fact the wing would be more efficient at producing lift but would suffer more adverse yaw. All other moments, etc seem fine (large hor stab, long tail moment)

Hope somebody can help.

William Robison

My Feedback: (3)

mahalalel:

The Duellist is indeed an excellent flying airplane,

But the Westland Whirlwind HAR series is the British license built version of the Sikorsky S-55 helicopter.

So I suppose you mean the earlier Whirlwind, the twin engined fighter from the mid 1930's.

I think if you consider the wing taper, the engine nacelle positions, and so forth, you might be well advised to start with the Grumman F7F Tigercat instead of the Duellist. Or possibly even closer, the Mosquito's little brother, the deHavilland Hornet.

But whatever you do, please don't limit it to scale power. The Rolls Peregrine engines were the weak point of the plane.

The Whirlwind was a real schizoid,
. Fixed wing, also a rotary winged "Boid."

Bill.

William Robison

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Mahaliel:

Sorry I didn't include this in my first response, I needed to get some free time to dig the plans out and measure.

Rather than the version kitted by Pica, I have used the later Mk II version for reference.

Since you are planning major changes I thought you might like the better flying version, and would not want to buy so much material that you would not use.

But let me clarify that "Better flying version" here. If you're never going to fly inverted, or do any outside maneuvers, the Pica kitted version is better. The Mk II is more aerobatic. Take your choice. Both excellent airplanes. Just a little different.
If you use the Duellist style construction, I'd guess about a pound to a pound and a half.
Generally, the added wing area makes the power less critical - in other words with the same engines it will fly more easily, but a little bit slower.
The Duellist Mk II 2/40 has the engine center lines 12.5 inches from the fuselage center line, so your 11.57" should be perfectly all right.
Projecting the vertical fin and rudder to three triangles and two trapezoids it let me do some figuring. With no guarantee of extreme accurracy, the combined area of the vertical fin and rudder, including the area inside the fuselage, is 83 5/8 square inches. Of this, the rudder is 32.4 square inches - or just a litttle bit under 40%

HTH

Turned a Duellist into a Whirlwind?
. Against the Duellist, Sir, you have sinned.

Haw.

Bill.

Wayne22

My Feedback: (2)

A very noble quest !!!

There is a little bit of info on the whirlwind on the net, not much though.

JohnBuckner

My Feedback: (1)

Mahalalel

Sitting here looking at a three view The airplane appears to have reasonable proportions for a decent Rc ship. Since you said you intended to scratch build instead of bash a duellist. My inclination would not be to try to match moments and areas at all and instead go with scale or near to it. The high aspect ratio wing is a plus and the horizontal and vertical tail aread appear ample to do the job. If you wanted to soften up stability just a bit you might consider extending the fuselage maybe 10% which has the effect of increasing stability without going to non scale big surfaces.

The only other area of some concern is the fact that it is a conventional gear with a rather high stationary deck angle. If it were me I would cheat and extend the tailwheel a little to reduce the deck angle and simply use a gyro on the rudder. Your .46's and light build will be a nice power package. Should be a nice flyer.

John

William Robison

My Feedback: (3)

mahalalel:

Just remembered. There was a plan published by one of the mags about 2 years ago, for an electric version. Might want to check that out.

Or does anyone else remember it, with more specifics? Please respond.

You want to fly Westy's Whirlwind?
. You should be where the nuts are penned.

Haw.

Bill.

jetmex-RCU

My Feedback: (8)

A friend of mine has a set of plans for a Whirlwind for 2x.25 2-strokes, wingspan is about 65 inches if I remember correctly. They are Brit plans, I'll look them up when the work week is finished and post back if you're still interested.

monocoupe

My Feedback: (40)

Mahalalel,
I also have the British Whirlwind plans that jetmex has described. Yes, the wingspan is 65" and it calls for a pair of 30 to 40 size engines. The title block also says "1/8 near scale".
I would part with them if you're interested.
I also have some very nice and very detailed plans for a slightly larger one...seventy something inches, by the late Hal Osborne. I'm keeping these ones, but they are still available from another source that isn't currently at my fingertips, but I can find it for you if you're interested.

Cheers, Nigel

mahalalel

Thanks gentlemen for your replies and offer of plans. I was aware of the 2 x .25 plans and I think some electric ones also. I think I will go with completely scratch build as I have created the spreadsheet from hell in coverting the dimensions from the three views from an airlife book into a 79 inch wingspan whirlwind.

I've already drawn most of the airfoils and some of the fuse formers to scale in modelCAD, bought the retracts and ordered another motor and retract servo. I will start to build this week. Before I start to cut balsa would anybody like to convince me to go giant scale - is it 81 inches? It is easy to change proportions the way I have set my programs up.

Cheers,

Marc

William Robison

My Feedback: (3)

Mahalalel:

Don't knowhow it is there, but that 2" added would open a lot of doors in the USA, and the added cost would be just about nothing. Go for it.

Bill.

Wayne22

My Feedback: (2)

Actually 80" span will do it..... worth a little stretch since you are so close already....

paulrcpilot-RCU

My Feedback: (32)

Go ahead with your Whirlwind, I have built one from plans (can't remember who's) 74" span that I stretched to 80" by changing the rib spacing. It flew absolutely perfect, did things the full size never thought of. It was powered by Enya .45's wieghed about 10 lbs with flaps and retracts. It got killed in a friendly fire accident(someone turned on same frequency). I blew the plans up to 99" and will do another when time permits. If interested I can copy the original plans for you. Enjoy it looks great in the air Paul

mahalalel

Paul,

Did your whirlwind have scale control surfaces. They all seem to be adequate except the ailerons - seem a little lacking in chord. Did you widen yours? Also what flap arrangement did you build?

Thanks for the offer of plans, what I would be most interested in is the construction techniques used for the tail and engine nacelles - I have my own ideas but it is worthwile to check.

Marc.

JohnMac

Bill,
Well I had a model built from the Traplet EFI plan. It was 78" span,
weighed about 10lbs, had 2x Jeti phasor 30/3 motors and 20 2000 cells. It was complete with spring air retracts.
The plan was superb, good old fashioned modelling to keep the weight as it came out. I film covered it and painted it with Humbrol enamels.
How did it fly? Brilliantly!
Forget putting slimy noisy engines in twins, electric is the answer.
BTW, The model was designed by Peter Wilson who also designed a DH Hornet which flies just as well.
Sadly my model is no more.

JohnMac

Another shot

JohnMac

Final Shot

William Robison

My Feedback: (3)

JohnMac:

Very nice airplane.

Sorry to hear it is no longer with us.

Bill.

hoonnz

Mahalalel:

I'm a Whirlwind fan to, and I want to build one for 2 .46's. I have a scale Corsair to finish first, so it is not going to happen for a while. My early planning came out to around 77" span, but I have to say the size of the engine nacelles staggered me, the thing basically is like 3 fuselages, and even the spinners are over 4" diameter to be scale. Where do you get spinners that shape is another question.
Anyway, the main reason I entered this thread is to ask how is it progressing, and how about some construction pics etc?

Happy landings

HoonNZ

Connery

I am also a fan of this not so well known twin. I've been wanting to build a plastic model of the Whirlwind for quite some time but could never find one. Now that I'm back into RC, I'd love to find a set of plans for a large scale version.

scalebirdman

My Feedback: (6)

Good luck on your Whirlwind! I've been building a 1/6 scale (90" ws.) version off and on (mostly off) for a year or so now. I started with enlarging 3-view drawings with cross sections and going from there. I plan to use 2 90 size 4 stroke engines. Expect to come in at around 18 lbs (hopefully less) for a 40 oz/ft wing loading. For all it's span the Whirlwind doesn't have that much wing area, so weight is a concern. I have the fuse and vert tail framed and the horizontal tail/elevators built. I'd post the pix if I could figure out how(sorry pretty new to this forum).
I am keeping this as exact scale as possible including the L/G and flaps.

Vario-RCU

JohnMac Very nice bird nice to see that one esp on electric power [8D]
BW

barry wetherell

HI, guys, yes I am one of them as well< Whirlynutter, pete wilsons plan is quite good, built 1 fuz and 2 wings (dogs stepped all over the first one) for it,75" span, I redrew the wing completely, and added 2 x 54 4st,, complete with "fowler flaps" pic's are on another site in uk,the biggest worry is the 0 deg to 0 deg "incident" on tail > wing> engine thrust,. you have to keep the "back end" light. flight test tomorow. i also added more washout on the the tips. will keep you all informed. any information that i can give you all,I will , [email protected] thanks Barry

JohnMac

Hi Barry,
Mine flew straight off the board with the standard set up. It also doesn't need the extra washout, there were no bad habits. (then again, no harm in a bit more). Have fun, & post us some pictures.
Regards,

John

flyingpiggy

Hi Hoonz
I have a set of whirlwind plans here in Chch - Hoonhay to be precise.
Give me a ring on 3394060 sometime {after work} we can hookup

Regards
Dave Read
yea I use mixing - balsa and dirt!!!

Canuck1

A large scale Whirlwind would be awsome. Couple 45 CC gas engines you know that you would be the only one with one, very rare warbird.

Craig