SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Apr 17, 2004, 01:18 AM
de-registered abuser
gouch's Avatar
Lake Macquarie, Aust.
Joined Dec 2002
14,167 Posts
What do I power my shrunken Miles SparrowHawk with?

I am currently building a Miles SparrowHawk from some great plans drawn up by Graeme Greddin ("greddin" RC groups name) website for the plans are here. http://www.users.bigpond.com/greddin/

I have reduced the plans with a programme called "tileprint" to 36" span, then as I originally wanted to slope it so I stretched the wings to 40". But as the winds are going sour soon for sloping, I thought I'd power it up.

I have used the same wing technique as Nigel Hawes uses on many of his current planes. It is 12mm flat bottom with an "airfoil" sanded onto the top. My Tucano built from his plans flies very well, so I thought I'd try it on this one.

I will be fitting the landing gear as I think it really makes this plane.
Now for the questions, Could it be powered with a mega 16-15-4 that I have with a gearbox? I'm thinking a 2:1 reduction and according to specs I have from mega, this reduction on 10 cells will spin an APC electro 8*6 prop at 10790 rpm at 23 amps. this gives 944 grams of thrust, pitch speed of 61 mph
and 207 watts. Is this going to work? I would like to stick with this motor as I can't spend too much on power at the moment. I would have to buy batteries, what would work well at this type of current draw.

Maybe a 16/15 6 or 7 turn DD would work?? Would the 8 cell kan1050 packs work? I would only need to buy the motor and some Kans to power it with.
I am trying not to use a "600 size" power supply as I have to purchase all that stuff, batts motor gearbox etc and it starts getting a bit expensive, which is another reason I reduced the plans, as I thought from the start I may power it with what I already have.

I haven't weighed it as a bare airframe (no scales) but it's coming out pretty light so far. The weight probably needs to be worked out first for any advice i'm guessing?

Any help would be appreciated. I am using a CC Phoenix 25 controller and I think they can only use 10 cells with bec?

Cheers
Paul

P.S thanks for the plans Graeme. I know I'm not building it to the plans as they are drawn, but I like to experiment
gouch is offline Find More Posts by gouch
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 17, 2004, 08:14 AM
Registered User
greddin's Avatar
Sydney Kingsford, Australia
Joined Oct 2001
525 Posts
Hi Paul,

I'm glad you're having fun with the Sparrowhawk plans ! Having seen the terrific job you did on Nigel's Tucano in the other thread I'm sure this model will be a beauty too - looking great ATM.

FWIW my original (52" span) version has heaps of performance with a Thrust/Weight ratio of about 50%. If your Mega 16/15/4 geared gives you 994g static thrust you could build to an AUW of approximately 1900g for a similar performance. At the size you're building you won't get anywhere near that weight, so you'll be fine.

Please keep us posted with your progress!

Cheers,
Graham Reddin
greddin is offline Find More Posts by greddin
Last edited by greddin; Apr 17, 2004 at 08:31 AM.
Reply With Quote
Old Apr 17, 2004, 08:19 AM
Big gov never Works
St. Martin's Avatar
Skunk Water, Rhode Island
Joined Jul 2002
12,385 Posts
Quote:
Originally Posted by gouch
I am currently building a Miles SparrowHawk from some great plans drawn up by Graeme Greddin ("greddin" RC groups name) website for the plans are here. http://www.users.bigpond.com/greddin/

I have reduced the plans with a programme called "tileprint" to 36" span, then as I originally wanted to slope it so I stretched the wings to 40". But as the winds are going sour soon for sloping, I thought I'd power it up.

I have used the same wing technique as Nigel Hawes uses on many of his current planes. It is 12mm flat bottom with an "airfoil" sanded onto the top. My Tucano built from his plans flies very well, so I thought I'd try it on this one.

I will be fitting the landing gear as I think it really makes this plane.
Now for the questions, Could it be powered with a mega 16-15-4 that I have with a gearbox? I'm thinking a 2:1 reduction and according to specs I have from mega, this reduction on 10 cells will spin an APC electro 8*6 prop at 10790 rpm at 23 amps. this gives 944 grams of thrust, pitch speed of 61 mph
and 207 watts. Is this going to work? I would like to stick with this motor as I can't spend too much on power at the moment. I would have to buy batteries, what would work well at this type of current draw.

If your plane is light this may be too much power/wieght. Better on a 9-7SF/10-7SF APC's and 8-kans.

Maybe a 16/15 6 or 7 turn DD would work?? Would the 8 cell kan1050 packs work? I would only need to buy the motor and some Kans to power it with.

Yes! Use an 8-6E APC or sim. on 8 kans 25oz appox AUW is good. Any higher go with the /4 & GB.




Any help would be appreciated. I am using a CC Phoenix 25 controller and I think they can only use 10 cells with bec?
Yes, 10 cells on 3 micro servos
Cheers
Paul
Thats my experience with both set-ups.

Steve
St. Martin is offline Find More Posts by St. Martin
Reply With Quote
Old Apr 17, 2004, 08:41 AM
de-registered abuser
gouch's Avatar
Lake Macquarie, Aust.
Joined Dec 2002
14,167 Posts
Hi Graeme. It's a real cool looking plane in my opinion. I am finding a new found liking to these era of planes. As usual it will take me forever to get it to flying stage, but I thought i'd ask some questions now in case I need to change anything based on the replies I get.
Also the wing building method will allow me to chop the streched wings down if warranted, which was what I did with the Tucano.

So if I go with the 4 turn setup with a 2:1 gearbox on, any particular brand to sway towards?

Although after more reading the threads, what about the slower? winds in the 16-15 range for direct drive for less current? I could then stick with the lighter Kans and not stress out my current E$C.


St martin: I'm not sure I understand your reply

Cheers
Paul
gouch is offline Find More Posts by gouch
Reply With Quote
Old Apr 17, 2004, 10:12 AM
Big gov never Works
St. Martin's Avatar
Skunk Water, Rhode Island
Joined Jul 2002
12,385 Posts
My answers came mixed in italics with your reply. I have to learn the new format..

I like the Mega 16/15/4 & 2.5-1GB 14A on 8 cells/10-7SF.

Steve
St. Martin is offline Find More Posts by St. Martin
Reply With Quote
Old Apr 17, 2004, 12:26 PM
Trampling out the vintage
Joined Feb 2002
1,892 Posts
Yes it would be helpful to have your airframe weight and area. However, at 36" span and that scale-looking wing, I second St. Martin's advice, provided you stay below about 30oz AUW or so. I have had that mega/gearbox/battery combo in several planes and it's fine. Your build quality looks excellent so with luck you will be way under that 30 oz possible weight limit.
4 Scale is offline Find More Posts by 4 Scale
Reply With Quote
Old Apr 17, 2004, 12:39 PM
HyperFlight Support
Neil Stainton's Avatar
United Kingdom, England, Stratford-upon-Avon
Joined Feb 2001
3,910 Posts
Is your wing really carved from 1/2" (12mm) balsa? Nigel Hawes smaller models use 1/4" (6mm) balsa sheet. I think the structure weight and wing area are necessary before anyone can be sure they are suggesting the best setup - however the geared Mega 16/15/4 with 8 Kan 1050 cells should be OK.

Neil.
Neil Stainton is offline Find More Posts by Neil Stainton
Reply With Quote
Old Apr 17, 2004, 08:23 PM
de-registered abuser
gouch's Avatar
Lake Macquarie, Aust.
Joined Dec 2002
14,167 Posts
Sorry St martin, I didn't see them in there . I have to learn the new format too! Thanks for the tips.

Quote by St martin:

"I like the Mega 16/15/4 & 2.5-1GB 14A on 8 cells/10-7SF"

Any recomended 2.5:1 gearboxes that I should be looking at? I like your suggestion as all I will need to buy is a gearbox and prop, I have the rest.

Neil: after seeing your reply I wondered myself on the thickness. It's 9.5mm thick, not 12.5 I did go off the 45" plans I have of the tucano and it uses 10mm balsa.

Greg: The span is actually 40" with the 36" plans.....If that makes sense. I scaled down to 36" than streched the wings out to 40 as I was going to slope it. As far as excellent build quality, I didn't do a close up for a reason!! Take a look at the lightweight spackle it needed

I will weigh what I have done so far, add the weights of different motor batt combo, add it to the radio weights and report on it. I'll try and get some scales today, I think we need a new one for the kitchen anyway

Thanks for the help so far everyone.

Cheers
Paul
gouch is offline Find More Posts by gouch
Reply With Quote
Old Apr 17, 2004, 11:39 PM
Fe Fi Fo Fum
Large One's Avatar
Useless Loop, Australia
Joined Apr 2001
1,295 Posts
Paul,

I thought you preferred gravity as a power source?

Rich
Large One is offline Find More Posts by Large One
Reply With Quote
Old Apr 18, 2004, 03:24 AM
de-registered abuser
gouch's Avatar
Lake Macquarie, Aust.
Joined Dec 2002
14,167 Posts
Hi Rich, how's things?
Yeah, I have gotten the electric bug lately and it's gonna get too cold soon to be standing on an ocean cliff with a 30 knot southerly! And I need a couple of planes ready so I can come down for a fly with you one day.

Cheers
Paul
gouch is offline Find More Posts by gouch
Reply With Quote
Old Apr 18, 2004, 05:16 AM
Fe Fi Fo Fum
Large One's Avatar
Useless Loop, Australia
Joined Apr 2001
1,295 Posts
Things are good, and you?

Sundays 9-5
Large One is offline Find More Posts by Large One
Reply With Quote
Old Apr 18, 2004, 07:53 AM
Big gov never Works
St. Martin's Avatar
Skunk Water, Rhode Island
Joined Jul 2002
12,385 Posts
Mornin' Paul, I like the Mega GB.

Steve
St. Martin is offline Find More Posts by St. Martin
Reply With Quote
Old Apr 19, 2004, 06:29 AM
de-registered abuser
gouch's Avatar
Lake Macquarie, Aust.
Joined Dec 2002
14,167 Posts
Rich: fine thanks

Steve: Mornin'....I mean good evening! I added the mega gearbox to my Aircraft world order tonight. I think this setup should suit an old 7 cell glider I have too.

Cheers
Paul
gouch is offline Find More Posts by gouch
Reply With Quote
Old Apr 19, 2004, 02:40 PM
Registered User
Mid-Michigan
Joined Aug 2002
2,178 Posts
Have used the Mega 16/15/5 with 2:1 gearbox with great success on models that size and weighing up to 24 oz. Before the LiPo craze hit me, flight battery was 10 KAN 1050 cells, but now that Apogee 830 LiPoys are available, I'd use 3S 2P of those for a substantial weight reduction.
uscra112 is offline Find More Posts by uscra112
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
what do i set my polycharge to for this bat? FlightCrazed Batteries and Chargers 2 Oct 11, 2005 07:24 PM
What do you seal your acrylic paint with on foam? czechyour6 Parkflyers 3 Mar 20, 2005 11:48 PM
TruFlight 3D what do i set my Dragonfly #4 clone TX what settings work? haddorh Micro Helis 4 Jan 20, 2005 03:44 PM
What do I put my Himax in? T_MECO 3D Flying 3 Jan 19, 2005 04:03 PM
What to do to fix my HB problems now? tocano Micro Helis 8 Sep 29, 2003 08:30 PM