mclina

This idea came to me on my way home from work today, and it took me about three hours to build. I have been wanting to make a small, electric SPAD. I tried this power system on a Gnat, but it was too heavy.

The wing is made from an 18"x24" piece of 2 mil, and the fuse is a 24" piece of 3/4" aluminum. All up weight is around 22 ounces.

The power system is the TowerPro 2409x12 combo from Hobby City, with a 1550mAh 3S Rhino LiPo. I used a 4 channel GWS RX that I had, and some of the $2.99 Hextronix servos from Hobby City. I had all the materials already, but if I had to buy everything, this whole plane would cost about $60.

I included a picture of it next to a Gnat carcass for size comparison.

Let's hope it flies.

NvMike

I am looking forward to see how it flies.
Does one servo connect to both elevators on the V tail?

mclina

Yes. I soldered the pushrods into a Y for the elevators. I may have to fiddle with the geometry a bit. I get about 1/2" of upward deflection but less than 1/4" downward. I really don't like V tails, but I already had one from another plane, and I had the angle for the fuse, so it was the easiest way to go.

If it turns out that it flies good and has plenty of power, I may try to rebuild it with a conventional tail and some really light landing gear.

draftman1

Thats pretty cool Mclina. how thick is the spar? I need to build a tough little electric plane. the depron just isnt durable enough

zertsman

is it a flat bottom wing or symmetrical? i thought abot doing the same thing but with a yardstick for a fuse..

you might have to slot your hinges to free them up some..

mclina

I just used a piece of full-width yardstick for the spar. The wing is supposed to be flat-bottomed, but it raised up just a bit in front before the glue set. It is pretty much identical to a Derelict wing, just smaller.

I tried to maiden it today. It turns out I needed more down elevator after all [] It did a half a loop and came right back at me, and I couldn't get it to level out. The power system was a success, it pulled right out of my hand.

I fixed the elevator pushrods this afternoon, so I get a good 1/2" up and down deflection, and I got the CG a little further forward. It should be much better now.

I would really like to have landing gear on it, though. Those TowerPro motor shafts just bend so easily, and I have a feeling this thing will go through a lot of props and shafts.

zertsman

slide on a propsaver and cut the shaft off just about even with the propsaver.. it can still bend if you doink the housing of hte motor on something, but cutting the shaft will let the prop fold over to save you lots of the time..

mclina

Is there a secret to using a prop saver? I tried this, but I don't get nearly as much thrust from the prop as when it is held on rigidly by a nut. It seems to vibrate a lot at higher speeds. What could I be doing wrong?

mclina

Here it is with a one ounce landing gear attached. I don't think it will track straight enough for a takeoff, but it should help on landing.

zertsman

i use a rubberband and go around and around till i run out of "slack". they are pretty tight, but you don't want it so tight that it bends the prop.. but you can get them pretty snug..

mclina

I finally 'flew' this thing a couple of weeks ago. It was nearly uncontrollable, partly due to WAY too much aileron travel, and also it was a little tail heavy.

I decided to cut some weight by going with a yardstick fuselage and ditching the landing gear. It now weighs in at a slim 19 ounces. I also cut the aileron travel down to 50% at low rates, and put on a traditional tail.

I'll try to give it another toss today or tomorrow.

rrh

Your front wing mount rubberband is inducing way to much up thrust on your motor. I have seen planes with a lesser condition come close to hitting the pilot in the keester upon launch. You will not have a successful flight as it is.

r

mclina

Thanks for the warning. I will try to flatten it out, or figure out a different fuse.

mclina

I have flown this thing a few times now, and I can finally say that it is a fun, cheap little plane.

I really had to tone down the control throws, because it is a real handful, but on my last flight today I had it screaming down the field straight and level, and it was a lot of fun to fly. It flies very similar to a Derelict combat plane (no surprise).

I ended up sticking a 1/4" dowel under the LE of the wing, and then putting some extra rubber bands on the underside of the wing, to straighten out the fuse a bit.

Unfortunately, when I landed on my last flight, the fuse gave out behind the wing where all the rubber bands were tugging on it. I just need to splice it back together, or come up with a different fuselage setup, but now that I know it will fly well, it is worth the effort.

The guys at the field were impressed at how well it flew and how cheap all of the components were.

mclina

I got it back together this morning. I glued two pieces of yardstick together and then wrapped them in duct tape, then I just glued on the old tail section, including yardstick, so that I didn't have to redo the servo.

It is probably a bit heavier than it was, but not by much. It will definitely be tougher now.

brett65

My Feedback: (18)

So you made a HORE? Hell On Rails Electrictrified!

mclina

Funny, that's exactly what I called it the first time I tried to fly it. Maybe I should cut out some letters.....

avroarrow

Looks like your getting things sorted out. I tried and electrified the gnat design.Similar to what you've tried here, I tried a few things and that large Lipo at the front of the leading edge is just about exactly where mine balanced out too. I used a tower pro combo, 18amp esc, 2000 mah lipo, 1047 gws prop, hitec 55 micro servo's(2 in each aileron),.hitec 65 in the elevator... fixed rudder. it took 3 different motor and prop trys to get one that worked. wouldn't fly on a geared 400, went to brushless tower pro,2908- 12, 9x7 and still barely flew. Propped up to the gws 10 x 4,7 and it finally flew, not great but flew just the same. I used the aluminumn "I" beam for a fuse(3/4in), 4mil coro(all I had handy) for wing and tail material , 2000 mah 20c lipo battery, music wire landing gear and foam wheels. I guess I should see what this weighs some day, but it flew. Slight breeze and I was in hover, as it really doesn't have a lot of power. Conclusion would be , the plane if flown with this motor and prop combo really needs a serious diet, But then you'd be into a lot more money for better materials and gear. all in all, the gnat flies on electric, but better performs on the 15 OS glow. I built a gnat with an OS 15 too, just comparing, the glow turned out much better and was really cheaper to run when you consider the 70 bucks for the battery on the E version Gnat.
I have found a new inexpensive source of brushless outrunners and might try this project again with a more powerfull motor combo...but so far the cheapest way is with a glow set up, and the best performer too.
I'm going to make a wing like yours to see if I can get more lift than the "J" type wing on the gnat, this should also help the underpowered e version . I had a pair of skis on mine to start last year , early in the spring as it was March when I tried to maiden the gnats. I like the enexpensive Idea of the simple materials and construction, SPADS are defintley fun!