|Oct 11, 2010, 12:37 AM|
De Havilland DH-53 Hummingbird 53" of course
After taking about a 4 year break from building airplanes to ride dirtbikes, a recent injury has left me relatively housebound except going to work, so what to do I do...build airplanes. (Ironically it was not the dirtbikes)
Enter the DH-53 which I've been staring at photos of on my computer for a couple years. How big? Most of my planes seems to be 40-45" span, lets make this one a little bigger. How about 53" wingspan...which I didn't realize the coincidence until about 3 weeks into the design.
1) Stick fuse
2) 1 Piece Wing
3) Scale working cables, which will prevent #2
Loooong Tail Moment
Laser Cut everything possible, only about 4 sticks in the whole plane.
Scale working cables
Moved Everything as far forward as possible.
Two piece wings due to scale cables
For the nose weight, I wasn't terribly careful about weight up front, plus I figure I can just use a bigger/heavier motor. I don't need much power. I have it set up for a Venom V35 Outrunner, to be run on 3S 4000. The battery is removed through a removable hatch on top of the fuse, from the cockpit to the firewall. For the rudder/elevator servos, it is designed for HS-81 servos, accessed through a hatch just behind the firewall. Both are linked to their scale bellcranks.
The tail uses laminated bows, and scale rib spacing.
Wing, also uses scale rib spacing.
The CAD file says 40 hrs and 2 minutes total editing time...not bad. 302 parts....10 sheets of balsa. etc...
Big thanks to Joe Pierson who has been digging around finding a lot of detail photos for me.
I just finished the design tonight and sent the file off to Charlie... until then, please enjoy these nice screen shots of my design progress.
More to come.
|Oct 11, 2010, 09:07 AM|
Is there room to put the battery vertically behind the firewall? That's the only way my YMF got balanced.
Parts will be cut tomorrow
|Oct 11, 2010, 07:04 PM|
Joined May 2001
De Havilland DH-53 Hummingbird
Now that is going to be a really Neat, Scale flying DH-53 Hummingbird And I am going to get to be one soon!! Paul is doing great job designing a Neat Electric DH-53 This Airplane has a lot of "Character" And I need a brake from riding my Indian
|Oct 20, 2010, 10:01 PM|
First bit of progress. The top battery hatch is the forward bit of fuselage decking you see. Its all just slotted together, no glue yet.
|Oct 21, 2010, 03:43 PM|
The 53 is a very compelling subject. It practically shouts "fliver". Could be a wonderful slowflyer.
She is an alluring siren, with a weight problem. In particular it is the mass moments. The Venom V35 will indeed provide excess power, if she is capable of scale like flight. Solving her balance issue with large lumps of motor and battery are going to steal her light plane flight charms.
I am doubtful that you have enough margin in your design to solve the long tail moment issue yet. My guess is that all that lumber, aft of the C.G., in the fuselage, is going to drive you to add ballast in the nose.
Tuned in, and eager to see this bird fly.
|Oct 21, 2010, 04:07 PM|
Love the work so far!
That short nose and long tail do look daunting, don't they?
The only way to ameliorate the problem (IMHO) is to really minimise all the wood aft of the CG, move all the hardware as far forwards as possible, and then add ballast as necessary.
Once upon a time, us e-flyers used to treat ballast as the Most Evil Thing in Creation (given the limited power/heavy cells combinations that were open to us), but these days we have as much power that could ever need, so adding a tad of weight is no longer the cardinal sin that it once was!
|Oct 22, 2010, 01:17 AM|
Built the ailerons tonight, though still need to add the laminated tips. Those will be coming this weekend. I only got about an hour in tonight.
When I designed it, I made it so all the cross braces were cut at 90 degree angles, made it much easier on me when building, see photo 3.
In the 2nd photo you can see how the ribs start to thin down as you near the tip. The full scale airplane, though a constant chord wing, did this...and I tried to reproduce this on my model...badly.
|Oct 22, 2010, 03:06 AM|
Joined Jan 2009
thought you might be interested in my Hummingbird. From aeromodeller plans, July 87 issue, designed by Jim Fullarton. It is 1/8 scale or 44 inch span, originally for 1cc diesel free flight. I installed a mega 16/7/6 and it flies very nicely. I doped the thin balsa turtle deck and forgot to add some plasticiser, so it has that starved horse look.
An aircraft of great character. good luck with yours.
|Oct 22, 2010, 10:25 AM|
United States, VA, Arlington
Joined Dec 1996
Good luck with your project. The DH-53 makes a great model. I designed and built one back in England, around 1990, 60" span or thereabouts for an OS26 fourbanger. Electric will be way better - make it easier to build that tiny flat twin into the nose.
My tailfeathers were mostly holes with light balsa laminated outlines - they are a long ways back and there's not much nose to balance them up front. Best I can recall, mine had most of the RC gear up front and had no issues nor need of ballast.
Fuselage was mostly 1/16" very light sheet balsa, with minimal structure inside, to replicate the prototype's ply sheeted fuselage. I didn't even cheat and leave the underside open framed.
Built her with two piece wings, wire joiners into tubes in wing panels and fuselage, with structural wing struts. Why not - you can't miss them, they'd weigh as much if they were just for looks, so make them do something useful.
Unfortunately, my photos of the model are somewhere in the old boxes of 35mm prints, but I replicated DH's circular aileron drives in the bottom of the wing with servo disc output arms. That allowed me to mechanically induce the massive aileron differential DH was prone to using.
Being of that nature back then, I also replicated the full size's rudder and elevator operation, with wires everywhere and the 'rudder bar' protruding out from the front fuselage sides.
Flew fine. With the narrow track gear, she demanded an into wind take off, though the wingtip skids did work as advertised once or twice... In the air, pretty docile - the huge tailplane on a long moment makes her easygoing in pitch and the vertical area is more than adequate for amiable handling.
Bragging here - but I hand-drew every wing rib. Managed to fudge one to do double duty, but that was it. The full size used a section based on RAF 15 - undercambered, with reflex at the rear, on the bottom, but varied to the familiar shapes on the topside of each section.
The LE sub-ribs were eyeballed!
Kept the plans for years, always intended to CAD them up but never did. Have a lot of info on the type, including two rolls of film worth of prints of OW's airworthy example. Once lent someone the negs to make their own prints off - guess the result, can't you?
Good luck, awaiting more on this fascinating model
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