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Sep 23, 2003, 11:39 PM
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New 52" span Miles Sparrowhawk flies


Yesterday I finally concluded a project which has been bubbling away in the background for a number of years: a Miles Sparrowhawk for 10 CP1700-sized cells, buggy motor and Master Airscrew gearbox. All I can say is that the result was worth waiting for!

Like so many of the British lightplanes of the Thirties,the Sparrowhawk is ideally proportioned for a flying model and in this case the model incarnation truly flies just like a trainer. It is very amply powered with the simple drive-train described, cruises on 1/3 throttle, and gave me the confidence to throw it into a roll after only a minute or two of flight.

Full details of the model plus construction pictures are on my website, where the CAD-drawn plans for this model will be free to download in a few weeks' time (once I have tidied up the drawings). There are also two short videos of the model's first takeoff and landing. I hope you enjoy!

Cheers,
Graham Reddin

www.users.bigpond.com/greddin

Oh, BTW , astute viewers will no doubt notice I have yet to fit a windshield (my excuse is there's no pilot yet, so he doesn't need one!)
Last edited by greddin; Sep 23, 2003 at 11:45 PM.
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Sep 23, 2003, 11:51 PM
B for Bruce
BMatthews's Avatar
ABSO-LOOOOTLY GORGEOUS ! ! ! !

I look forward to seeing the plans. My own charger limits me to 7 cells. From what you describe I suspect I could get away with that as long as I used a semi hot wind buggy motor? What do you think? How many watts are you set up for in your current setup?

The Sparrowhawk has always been on my "To Do" list. This may just make my mind up for me...
Sep 24, 2003, 01:47 AM
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Bmatthews

Thanks for the kind words! I think it would be possible to power the Sparrowhawk with just 7 cells if you built very light - using a brushless motor would guarantee it, but I guess that defeats the purpose!

My setup only draws a modest 240W hot off the charger (22.5A @10.7V). I had originally planned to use a Magnetic Mayhem with the MA 2.5:1 gearbox, but ended up installing an ancient Trinity 16-turn buggy motor salvaged from an equally antique EDF model. This is used with the MA 3.5:1 gearbox turning a Bolly 9.5 x 6 brown IC prop. All very low-tech stuff, but it works really well.

You may wish to run the numbers for 7 cells through one of the Calc programs to see how they compare with the numbers I have posted on my website for the Magnetic Mayhem on 10 cells.

Hope this helps!

Cheers,
Graham Reddin
Sep 24, 2003, 09:28 AM
Visitor from Reality
Hi Graham
Beee-Yooo-Teee-Full!

This era produced some gorgeous flying machines - I've seen the full size of yours at Old Warden before we left England, and it looks like you really captured the "air" of the type.

I'm going to have to check out your plans. Ways back in England, before I caught electricity full time, I designed a Chilton DW1 to about the same span, for an Enya 40 FS - the original open rocker version. Have often thought of making another for electric power. THe fun part was the UC inside those full depth UC trousers, or whatever you'd call them in Oz. I started with a torque rod set-up - the first landings pushed the trousers back through the wing bottom. A hard evening's balsa bashing turned it into a really stiff gear with no play anywhere!

Even so, I had two sets of trousers - a neat set for scale judging and the original, somewhat battered set shorted a fair bit for actually flying.

Giving the plans away! We should have a private chat over imaginative ways to fund our favourite pastime...

Regards

Dereck
Sep 24, 2003, 10:12 AM
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Graham, you clever man!
Dereck is right as usual. That is a beautiful model and I agree the plans should be expensive (profitable for you) to obtain. But I must add this rider; they should be expensive for those who are silly enough not to live in Godzone country (OZ!). As for mine, well, there's this ND10 with a 4:1 GB and 14 cells just waiting and when you release the free plan for Australian consumption, I'll be right there! (Its a tremendous model, even worth me sending youse a slab for the plans!)

hugh
Sep 24, 2003, 11:43 PM
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Dereck

I appreciate your kind remarks, thank you. Actually, seeing your most delightful Chilton in the September 1986 edition of RCMW encouraged me to start drawing plans for an electric version, with the thought of offering it to one of the magazines. I progressed as far as building the tail surfaces before I realized that there was no point reinventing the wheel and so turned to a design that had not been done in that size before (the Sparrowhawk).

Whilst building the Sparrowhawk Mike Payne published plans in EFI for a larger version, so thought I would make my plans available anyway, but FOC. The world needs more British lightplanes in the sky to keep the Chiltons company!!

Like you I went through lots of head-scratching before I came up with the U/C arrangement on the Miles. My choice was to use fixed struts rather than a torque-tube arrangement, and so far so good.

I'll attach a photo of your Chilton below so that the populous can dribble into their keyboards, and hopefully inspire them to rush out and buy copies of the plan by the truckload!


Cheers,
Graham Reddin.
Sep 24, 2003, 11:55 PM
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oneson1

Thanks indeed for the nice comments. FREE plans - must be all the blood running to my head from living in this upside-down part of the planet! (P.S. I have lived in Melbourne for about a year in the past too - great city).

The plans will be available on my website as soon as I have tidied up my CAD files and taken some more pics to aid construction. Keep an eye out here in the Scale forum - I'll post when they're ready to download.


Cheers,
Graham Reddin.
Sep 25, 2003, 11:10 AM
Visitor from Reality
Hi Graham
TVM for running that shot. For some reason, I sold the model and engine to an old RAF buddy (who is now the chief trapper pilot at the CAA, of all things) and often regretted that move. The engine was more like a noise producing lump of nose ballast - I suspect even the first OS20 FS would have done as well, and the 26 Surpass would have done fine - so an electrocution would work fine.

if you want to see something ugly - and I don't have a photo - you should see the Chilton fitted with a flat four Talk about an object lesson.

If anyone is fascinated by pointy wingtips - I had the ailerons rigged with massive mechanically sorted differential - about 1/8" down, 3/4" up IIRC. Despite that, she'd do a very nice slow aileron roll and was no problem with tipstalling. I did fly her some with a lump of lead under the tail end to get her to where I could spin her, but I could get around a scale comp pattern without having to nominate a spin, so the lead got lost and aft CG flying was put down to 'envelope expansion'.

She was no sweat flying with the aft CG, BTW. OTOH, I ran into a guy at one meet with a huge - at least 25%, possibly larger, DW1A. He'd built it from a plan, 'improved it' as such tend to and was bemoaning how his would snap off the tops of loops, spin from tight turns and other such horrors. Dead straight faced, I offered mine didn't do any of that. I even kept the deadpan look when he asked me what mine weighed. When I told him 3.25lb for 54" span, I couldn't resist adding "But big models always fly better".

Funnily enough, RM published a Chilton about a month or so after RCMW ran mine. It was only some 4" longer span than mine, but was a DW1A with the inverted four banger and high propline, by the late Brian Peckham - one of England's best and most prolific designers. I often thought his would be a better starting point for an electric, with the higher thrustline.

If anyone has Riding's book on the British 20's lightplanes, I've got much of the drawings done for a "Watkinson Dingbat". Nowhere near as sexy as the Chilton, but it flew well enough and is still in existence - might even be flying again by now in England. Low winged single seat, slab wing panels on a short flat CS, slabbish tailfeathers and an in-line-ish cowling. The UC is an open frame effort - main shock struts, drag links and diagonals to the centreline. Stiff and rigid from wire on the 10 cell, 56" span version, but the quarter scale one would probably benefit from springing.

My other project is one of my all-time favourites - Henry Ford's Flivver # 286, the first one. My old Radio Modeller plan Flivver hangs up in our guest bedroom nowadays, and there was at least one in England flying on 7 or 8 cells. Still, I like the type a lot and have two plans under way - one for geared S400, the other is 25%, all of 65" span, for 16 - 20 cells. Have to build a three pot Anzani, and it really needs sprung gear at the larger size, but it is a cute little thing in the air - once you get used to flying a top heavy model with a completely flat wing on the bottom of the fuselage. That is fun - it's very relaxing to fly inverted!

I need another scale design - the Cub's nice but it's a kit, which doesn't really count.

Regards

Dereck
Sep 25, 2003, 09:33 PM
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Hi Dereck,

Thanks for the heads-up on the Chilton! I have seen pictures of the Chilton with the flat-four (a yellow and black Canadian example, if I recall correctly) and yes it truly had a nose not even a mother could love!

BTW, did you track down the Aeroplane Monthly article about the Dingbat? Let me know if you didn't and I'll send you a copy if it would be of help.

Cheers,

Graham Reddin.


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