Can the Dumas Hughes H1 Fly? - RC Groups
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Jan 12, 2006, 09:42 AM
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Bfly's Avatar

Can the Dumas Hughes H1 Fly?

Has anyone built/converted and flown the Dumas H1? It appears that it is advertised only as a display model, but even that is unclear looking at the Dumas site. My search of the forums doesn't find any completed, flying models.

Thanks for any information.
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Jan 12, 2006, 10:15 AM
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P. Tritle's Avatar
B, I've converted several of the 30" Dumas FF kits to R/C with complete success. I have been of the opinion for many years that anything will fly if it's light enough! Based on past history, I see no reason this one would be any different. I'd say "Go for it".
Jan 12, 2006, 11:09 AM
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Bfly's Avatar
Very well, I'll give it a go (after two guillows models in front of it). I'm just surprised no one else has done the H1 yet. I'm new to FF balsa conversions, and was hoping to learn from other's experience on this one.
Dec 21, 2008, 09:30 PM
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podavis's Avatar
This is the only thread I found when I did a search on the Dumas Hughes 1B. The kit has been sitting in it's box for at least 2 years waiting for my flying skills to improve. Since some of my planes haven't been flown in months because I have too many that are flight ready the time to build this conversion had arrived. (Think about the logic behind that) .

The objective is mid-range areobatic performance, reasonably scale looking with a swappable battery pack. The motor will be a mini-GBx, battery pack a 21 gram 7.4v, max 6 amps.

I had dillusions of a 5 ounce wing loading for a couple weeks, it's going to be 6. The wing area by my calculation is 144 sq in, 1.0 sq ft.

The stringers and wing spars are cut from Midwest basswood, but I'd swear it's poplar. The belly is sheeted with 1/32 balsa because it may not get landing gear. All balsa is contest balsa or very light balsa from LHS'. Right now it's 92grams with the canopy. That darn canopy weighs 3 grams trimmed down as small as possible! If this plane ever wrecks the canopy is sure to survive.

I have mini-GBx's in a SA Dystraction and a Dumas Pilatus Porter. It's a terrific performer and it could pull this plane staight up , but I think I'd rather go for longer flight times and higher pitch speeds.

Servos will be ARCED 4.5g Ball Bearing Digital from gobrushless. I have this brand in 3 other planes, so far so good. The ESC will be a Markus 6 amp. I'm using this ESC because it's BEC is rated for 2 amps. The Pilatus Porter mentioned above locked-up in flight 3 times before I figured out it's 4 servos were over heating the voltage regulators on the 2 different ESC's I tried in it. (Melted heat shrink over the BEC chip solved the mystery).

The only thing that's undecided at this point is whether to put landing gear on it. I can do that for 5 grams or less using the method for attaching landing gear of the Dystraction. In fact, I can use the Dystraction landing gear because the wire fatigued and broke off just where it comes out of the wing around its 130'th flight and might be long enough for this plane. The Dystraction hand launches reliably with a gentle underhand nose high toss. I'm not sure I want to chance it with this plane.
Dec 21, 2008, 10:30 PM
scratchnhover's Avatar
Great work! S/B a terrific flyer at that weight, assuming your pitch speed is correct. What RPM and prop will you be using? You will love that access hatch you added- pulling the wing off to change a battery really blows. Nice job.
Dec 22, 2008, 01:16 PM
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podavis's Avatar
Originally Posted by scratchnhover
What RPM and prop will you be using?...
Thanks for the kind words.

I will see if I can get a good wind with 19 turns. The website has 19t data for 26ga. I have a spool of 32ga (0.2mm) and ordered a spool of Dan's 29ga hi-temp so if I can completely pack the stator with some combination of the two and get 19 turns cleanly that's what I'll do.

The mini-GBx on the Pilatus Porter has about 26t of 28ga (I didn't write it down, doh!) terminated delta and it buzzes at full throttle. Since there's no c-clip on these I suspect it's thrust limited by the rotor pulling forward off center of the magnets, the buzzing might be this effect cycling. The prop is not the cause. The Dystraction weighs 7.9oz and its star terminated mini-GBx with the same yurns will just get it to a hover with it's SF prop. The P' Porter weighs 10.8oz but is a little short of hanging by the prop (why would I want it to, anyway).

If the 19turns works out I can start out with the GWS 7x3.5DD, then try an 8x4 to see if it doesn't hit the ESC current limit, make the motor buzz and that it adds to the top speed. Paul
Dec 22, 2008, 01:26 PM
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portablevcb's Avatar
I could only get 17T of 26ga on my last CDROM. But, I wasn't very experienced at it either.

That motor turned a 7x4 prop with a 3s730 battery drawing right around 5A for 50W output. The only limitation on these is the cowl sizes.

FYI, the Dumas Hurricane flew very well on a geared sp280 (35W) at 10oz. It had about 100sq in of wing area (but it was a very fat airfoil ).

This one should work very well.

Dec 26, 2008, 11:34 AM
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podavis's Avatar
The silver part of this Hughes 1B is 21st Century Microlite. The completed sections increased the number on the scale only 1 gram. I have some transparent blue of the same brand for the wings but it's very pale, the picture on the kit has a much darker blue; I'm undecided on this.

With all three servos, the ESC, battery, motor and prop in the plane the cg is looking like everything wants to be as far forward as possible. This is good because the canopy can be glued in place. This is bad because it's going to be a tight fit.

Landing gear are looking more likely since they'll go in front of the cg and pockets for their attachment have been built in. These can be added retro so hand launching can be tried while there are a few inches of fresh powder on the ground to cushion a failed launch. Avoiding landing gear might improve its top speed.
Dec 26, 2008, 12:07 PM
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podavis's Avatar
Originally Posted by portablevcb
...FYI, the Dumas Hurricane flew very well on a geared sp280 (35W) at 10oz. It had about 100sq in of wing area (but it was a very fat airfoil )....

charlie, thanks for the comments. I have to keep the weight down. I've built heavy wing loaded planes that fly great but landing them where I fly is the devil. I need something that can either slow way down or handle a fast landing on turf.
Jan 01, 2009, 12:39 PM
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podavis's Avatar
The fuselage is covered and servos are installed. The blue Solite for the wings will have to ordered. Both rolls of darker blue that are on hand would look beautiful but would add too much weight and would be stronger than necessary. The top of the wing might wind up being mostly silver for better orientaion tracking.

The servos are just in front of the wing spar. The middle lower servo is a GWS Pico because it's operating two aileron crank arms. The ailerons operate pretty freely. There is silicon grease on the CF tube inside brass bushings on the aileron torque tubes; maybe a couple grams could be saved using the 4.6gr Arced servo?

The top two servos are on slotted plates to adjust the pull-pull tension.
Jan 11, 2009, 01:12 PM
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podavis's Avatar
This Dumas Hughes 1B gettting close to flying. As shown it weighs 131 grams. The battery, ESC, Rx and motor are not included.

The kit comes with two wing number decals so I have a spare. The clear vinyl around the numbers was cut away and the numbers lifted from the sheet with air brushing frisket paper to keep them in place. This made it easy to apply them too.

The motor is 20 turns of 4 strands of 32 ga Belden magnet wire. This wire makes it easy to pack the stator to the brim and the coating doesn't need to be removed to solder it. Mint flavored waxed dental floss keeps the wire in place. The dental floss is visible in the photos. The wax makes it easier to get the floss under the tips of the hammer heads. The mint makes the motor smell good when it's new

There's no rush to finish the model because it's frigid here. The plane just feels right. I think it's going to be a good flyer, even at 6.5 ounces. Paul
Feb 02, 2009, 12:56 PM
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podavis's Avatar
I am happy to report that this plane is a wonderful flyer. I had to put an 800 mAh 2s battery in it to balance it it so it came in at 7.6 ounces. The extra weight didn't matter. Both days I've flown it were a bit windy but the H 1B handles it with dignity. My initial hand launches were nose high and the wind always caught it and sent it on a wild ride. The little H 1B has the stuff to fly out of very awkward situations. Once I developed the confidence in the plane to launch the plane level the wind was no problem.

I would describe the plane as a very capable sport flyer. It's very reliable in close because it makes tight turns effortlessly. We have over a half foot of fluffy snow so I took the exceptional risk of crabbing in the gusty wind to try to land it at my feet and succeeded a couple times.

My son didn't want to brave the cold to take pictures last time I flew it. I'll try to convince him next time.
Feb 02, 2009, 01:42 PM
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danrc's Avatar
Awesome work! I've been anxious to hear how this one flies!
Feb 02, 2009, 01:45 PM
It actually Flies!
Float Flyer's Avatar
Congratulations on the maiden!! I have the same kit and thinking of following in your successful footsteps.

Question: What sort of belcrank set up did you do for the ailerons?

BTW, I really like the lightness of the build you did.


Float Flyer
Feb 05, 2009, 02:18 PM
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podavis's Avatar
Thanks for the kind words.

The ailerons are attached to the 3mm CF tubes shown in the pictures. The CF tube is from BP Hobbies. It's thin walled so it's very light but doesn't split. The brass tube used for the bushings is 5/32 from K&S. The control horns are made from two layers of 0.8mm (1/32) ply cut so the outer plys are 45 to each other.

The CF tube is part of the hinge for the ailerons. The outer halves of the ailerons use the fuzz covered plastic sheet hinge material. I filled the brass bushings with a synthetic dry-type bicycle lubricant before glueing to keep the CA from wicking into tube. I think petroleum based lubricant might attack the epoxy in the CF tube. Plastic film between the wing and aileron is necessary during glueing. This is the most difficult part because it can get messy and the groove in the aileron needs to cut accurately so that you don't have to fill a gap.

I drilled the holes through the ribs for the CF tube in a straight line with a 12" 1/8 drill bit but it's possible to do this by sharpening the end of the CF tube with sand paper rolled into a cone to bevel the inside diameter. Make little notches on the sharpened end by nicking it with an Exacto and it will cut balsa. paul

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