Laddie M's Arrow - 2nd Attempt
#426
RE: Laddie M's Arrow - 2nd Attempt
Here she is in final form, with the Turnigy 46. They even send you a fancy chromed badge that says "Turnigy". I stuck it on the right side of the pod.
The 46 wouldn't begin to fit that Great Planes mount I was using, so I got some #8 SS wood screws and one inch long nylon spacers to mount the motor with, using the bell mount "star". My firewall is 1/4 birch ply, so it's strong enough to do that, especially with a mix of epoxy and milled fiberglass coating the screws and stuffed down into the holes.
The 46 wouldn't begin to fit that Great Planes mount I was using, so I got some #8 SS wood screws and one inch long nylon spacers to mount the motor with, using the bell mount "star". My firewall is 1/4 birch ply, so it's strong enough to do that, especially with a mix of epoxy and milled fiberglass coating the screws and stuffed down into the holes.
#427
RE: Laddie M's Arrow - 2nd Attempt
The only airplane I have that even comes close to being as well-mannered as this one is my Hangar 9 Pulse 60XT.
Today, for the first time, I was able to do a nose high approach (perhaps 25-30 degrees) while controlling the angle and rate of descent with the throttle. Just beautiful to watch, as she touched down on the snow and didn't even splash.
Today, for the first time, I was able to do a nose high approach (perhaps 25-30 degrees) while controlling the angle and rate of descent with the throttle. Just beautiful to watch, as she touched down on the snow and didn't even splash.
#429
RE: Laddie M's Arrow - 2nd Attempt
I dunno, the Rimfires are Chinese. Only difference between them and Turnigy seems to be 1) they aren't as good and 2) Someone else is importing them and marking the prices up 100%. I guess I'd rather buy direct and pretend to mark them up.
I've got seven flights on the Turnigy powered Arrow, and it's a great motor.
I've got seven flights on the Turnigy powered Arrow, and it's a great motor.
#432
RE: Laddie M's Arrow - 2nd Attempt
I wish I knew someone with a video cam willing to go down to the lake that early. Maybe someday.
Flew again today, after changing out the elevon servos. The old Airtronics non BBs were losing it. Roll control was getting real weird. A pair of HS325 hitecs did the trick.
Flew again today, after changing out the elevon servos. The old Airtronics non BBs were losing it. Roll control was getting real weird. A pair of HS325 hitecs did the trick.
#434
RE: Laddie M's Arrow - 2nd Attempt
Today was the first time this spring that the wind and the temperature cooperated so that I could fly the glow Arrow (#4).
I am always reminded, after every flight of this airplane, why it continues to be not only my favorite seaplane, but my favorite sport plane. Just a joy to fly. Fast and smooth and jet like. Plenty of power with the 46AX on a 10x7 3B, and running down around 12000 max rpm, a very long endurance on only 8 oz of fuel. (I could probably get a half an hour if I pushed it.)
This design was worth every bit of the effort it took to get it right, and to learn how to fly it correctly.
I am always reminded, after every flight of this airplane, why it continues to be not only my favorite seaplane, but my favorite sport plane. Just a joy to fly. Fast and smooth and jet like. Plenty of power with the 46AX on a 10x7 3B, and running down around 12000 max rpm, a very long endurance on only 8 oz of fuel. (I could probably get a half an hour if I pushed it.)
This design was worth every bit of the effort it took to get it right, and to learn how to fly it correctly.
#435
RE: Laddie M's Arrow - 2nd Attempt
Couple more items to add to the Arrow knowledge list:
1. I guess if you mess around with swept leading edge aircraft long enough, sooner or later you're going to run into Dutch roll. In the electric Arrow, it exhibited itself as a reluctance to "groove"- the bird kept wanting to drop one wing or the other, and any correction I made was too much, it wanted to roll over to the other side. It would not fly hands off with and stay level in roll. Didn't notice any nose wagging, but I've read that goes along with it. This is probably what made me think the original elevon servos were no good.
The cure was simple: move the CG up to 15" forward of the elevon hinge line, about a quarter inch further than it was previously. Just as stable as the glow Arrow, now. It would always drop a wing during landing flare before, and that's gone, too.
2. Cooling air for the ESC and seaplanes just don't mix. (At least ones where the ESC has to be way down in the hull and the motor's a long way away.) Made a bad TO yesterday, and the intake scoop let in enough water to flood the ESC and ruin it. Fortunately I had another on hand, and after repairs, rebalancing, and removing the scoops/inlets, I could go fly again. I used to always find a little water in the bottom of the servo bay after each flight. No more. The scoops were the problem. The Turnigy Trust 55 only gets warm to the touch, now, so I'm not worried about that.
A bit of knowledge gained on electric applications: a "knock-knock-knock" noise coming out of the motor at low speeds is a bad connection in the motor wiring somewhere.
This has been a good learning week. [:-]
1. I guess if you mess around with swept leading edge aircraft long enough, sooner or later you're going to run into Dutch roll. In the electric Arrow, it exhibited itself as a reluctance to "groove"- the bird kept wanting to drop one wing or the other, and any correction I made was too much, it wanted to roll over to the other side. It would not fly hands off with and stay level in roll. Didn't notice any nose wagging, but I've read that goes along with it. This is probably what made me think the original elevon servos were no good.
The cure was simple: move the CG up to 15" forward of the elevon hinge line, about a quarter inch further than it was previously. Just as stable as the glow Arrow, now. It would always drop a wing during landing flare before, and that's gone, too.
2. Cooling air for the ESC and seaplanes just don't mix. (At least ones where the ESC has to be way down in the hull and the motor's a long way away.) Made a bad TO yesterday, and the intake scoop let in enough water to flood the ESC and ruin it. Fortunately I had another on hand, and after repairs, rebalancing, and removing the scoops/inlets, I could go fly again. I used to always find a little water in the bottom of the servo bay after each flight. No more. The scoops were the problem. The Turnigy Trust 55 only gets warm to the touch, now, so I'm not worried about that.
A bit of knowledge gained on electric applications: a "knock-knock-knock" noise coming out of the motor at low speeds is a bad connection in the motor wiring somewhere.
This has been a good learning week. [:-]
#436
RE: Laddie M's Arrow - 2nd Attempt
Took the electric Arrow on our annual pilgrimage to Manistique Lake, and was able to fly off the dock eight times, as the wind was calm and the lake not too stirred up every morning. Great vacation airplane- with the wings off it takes up very little room in the Traverse so the wife can bring her usual tons of stuff without any hassle from me.
Hadn't flown the glow Arrow in quite awhile, due to the winds in Cadillac being very bad 24-7 for most of the last 30 days. Last night the lake calmed down and with a moderate south breeze I could go boil some water and punch some holes in the sky. I am once again reminded that the glow Arrow is my favorite sport plane.
Hadn't flown the glow Arrow in quite awhile, due to the winds in Cadillac being very bad 24-7 for most of the last 30 days. Last night the lake calmed down and with a moderate south breeze I could go boil some water and punch some holes in the sky. I am once again reminded that the glow Arrow is my favorite sport plane.
#437
RE: Laddie M's Arrow - 2nd Attempt
The E Arrow has never had quite the performance that her glow powered sister has, so I decided on an upgrade
Went from the Turnigy G46 670 to a Turnigy D3548/4 1100. It turns a 10x6 MAS S2 prop at 14,500 on the ground, drawing right at the 50 Amp max on 5 cells. Should have about 10mph more top end speed, and perhaps 15% more thrust.
Hope to find out tomorrow morning, if this wind calms down and the lake isn't too bumpy.
Went from the Turnigy G46 670 to a Turnigy D3548/4 1100. It turns a 10x6 MAS S2 prop at 14,500 on the ground, drawing right at the 50 Amp max on 5 cells. Should have about 10mph more top end speed, and perhaps 15% more thrust.
Hope to find out tomorrow morning, if this wind calms down and the lake isn't too bumpy.
#439
RE: Laddie M's Arrow - 2nd Attempt
I like it! I couldn't fly it very long today, but it definitely has the punch it needs. First time I've ever been able to loop it from level flight.
The new motor is so much lighter I had to move the battery pack aft, to one of it's earlier locations.
The new motor is so much lighter I had to move the battery pack aft, to one of it's earlier locations.
#441
RE: Laddie M's Arrow - 2nd Attempt
When I built it, I weighed all the pieces and it came to 6.4 pounds with the foam core wings, so it's probably a little less than that with the lighter motor. (5 oz difference)
Flew it again yesterday, and ended up moving the battery all the way back to where it was originally, getting the CG about where it is on my glow Arrow when it's full of fuel. (Maybe an inch behind the step.) The 5 oz down thrust and the correct CG are essential for takeoffs from any kind of rough water. Full throttle, full up elevator and after the third bounce, she'll be airborne. With the original 0-0 thrust line, this would always end badly.
I've learned a lot about Delta wing stability with this one. It has the same vertical fin area as the glow one, and the same engine/motor pod box. Evidently, there must be a lot of drag (and thus stability) associated with the glow engine and it's muffler hanging out in the slipstream that you don't get with the little electric motor. I never had dutch roll problems with the glow version, but I couldn't cure this one of it until I increased the size of the rudder. Even now it doesn't have the roll stability of the glow one, and I'll probably increase the size of the upper fin some day.
Flew it again yesterday, and ended up moving the battery all the way back to where it was originally, getting the CG about where it is on my glow Arrow when it's full of fuel. (Maybe an inch behind the step.) The 5 oz down thrust and the correct CG are essential for takeoffs from any kind of rough water. Full throttle, full up elevator and after the third bounce, she'll be airborne. With the original 0-0 thrust line, this would always end badly.
I've learned a lot about Delta wing stability with this one. It has the same vertical fin area as the glow one, and the same engine/motor pod box. Evidently, there must be a lot of drag (and thus stability) associated with the glow engine and it's muffler hanging out in the slipstream that you don't get with the little electric motor. I never had dutch roll problems with the glow version, but I couldn't cure this one of it until I increased the size of the rudder. Even now it doesn't have the roll stability of the glow one, and I'll probably increase the size of the upper fin some day.
#445
OK, guys. Here's the plans and the instructions in PDF. Remember: the CG is wrong on the plans. Measure 15-3/4" forward of the Trailing edge of the wing (not the elevon). That's where it belongs. Also, you'll need at least 3/8" up elevon trim for your first flight. Finally, you MUST put three degrees downthrust into the engine or motor, as compared to the centerline of the wing. If you don't, it will be all but unflyable. There's some other items, but those are the critical ones. BTW, I got my carbon fiber tubing from dragonplate.com. The 3/8" tubing for the wing spars will nest into their 1/2" tubing perfectly, without binding, so you don't have to make those silly boxes shown on the plans. Enjoy.
Last edited by Mustang Fever; 03-30-2015 at 11:45 AM.
#446
Join Date: Sep 2007
Location: Beeton, Ontario, CANADA
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Please clarify "Down thrust" as there is two perspectives on that topic.
Do you mean spinner pointed down towards the ground and exhaust towards the sky..or
Spinner towards the sky and exhaust towards the ground.
Thanks
Do you mean spinner pointed down towards the ground and exhaust towards the sky..or
Spinner towards the sky and exhaust towards the ground.
Thanks
#450
Would doping the wood before covering prevent dry rotting or is that what you did during your build? BTW, the 5 mile rule hasn't been made law yet(as far as I've heard anyway) so go ahead and fly.