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Author Topic: Floaty.. My 44inch span 78g motorglider  (Read 2337 times)

Andy M

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Floaty.. My 44inch span 78g motorglider
« on: September 11, 2020, 05:31:28 pm »

Here is my 44 inch span motor glider, Floaty, it is based on my 36 inch version with kyosho minium radio, which is in turn highly modified from a free flight chuck glider model called Jr's Pride.
 I had to cut the span down by about 2 inches so that the folded wing fits in my transport box. The fuselage was reduced in length by 20 mm for the same reason. It also had the fuselage depth reduced by 12mm to cut down frontal area a bit, still pretty big compared to what I have been building recently. The tailplane was also moved to underneath the fuselage so it could be banded on.
Using grey depron, with suitable bamboo and tape reinforcing, I have managed to keep the weight down quite well.
 It is 30% bigger than the minium version but only 14% heavier at 78.6g, ready to fly with one e-cig cell. It may need a bit more weight up front but theres plenty of room in the battery bay. Bit windy for testing just now but hopefully it will get calmer later and I can manage a test flight. I wasnt that keen on the grey depron at first but its super light and doesnt look too bad. I won't paint this one, keep weight down as much as possible.
The radio doesnt take up much room!
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #1 on: September 15, 2020, 11:37:15 pm »

Still too windy for flying, a couple of refinements while waiting for weather to improve, the cockpit canopy was painted and the tailplane seat has been sanded a tiny bit to level the tailplane. My friend had a look over it last night and we ended up gliding it back and forward to each other, in my shed! Its pretty cramped but we saw enough to know it is going to be a nice flying plane with a really flat glide. .
 The smaller 36 inch span minium equiped version, which cruises around level on quarter to a third throttle, was tested in the same way with much more drop in height from the same type of launch. The smaller one flies really nice outside, with a very gentle and predictable stall, enough power to climb steadily up to height and enough control to do some fairly tight turns.
 Here are some photos of Floaty finished. The battery slides into an angled slot just in front of the radio board, it could take 3 batteries, as I expected it to need a bit of weight up front, turns out it only needs one cell to balance, which is good, each extra cell would add another 6g, although after seeing it glide, I dont think that would affect it much.
 The small hole right in front of the radio board has the excess motor wires poked down into the cavity below. The hatch is a snug fit between the fuselage sides and this holds it firmly without need for any other securing.
 The 10mm motor/gearbox looks as if it will be a bit overkill, but we will see, I may be able to change to a syma 7mm motor and gearbox if the 10mm is vastly overpowered. I could put that on a plane that actually needs that much power. All 50g of it!
 A bit of calculation showed that in imperial values, Floaty has 1.7 ounce per square foot wing loading, I always regarded 4 ounces per square foot as being really light. Cant wait to try it, eventually.... when rain and wind stops.
 
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #2 on: September 15, 2020, 11:45:40 pm »

Radio and battery area
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #3 on: September 16, 2020, 12:53:39 am »

Eventually managed its maiden flight, although it was quite windy for such a light plane, it copes well. Nice flyer, capable of pretty slow flying. Here is video, taken with one hand while flying with the other hand.
https://youtu.be/SAjm5zhv0nM
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #4 on: September 16, 2020, 01:12:31 am »

Here it is dismantled and wing folded for transport. Glass fibre parcel tape hinges. Small bit of masking tape holds unfolded wing top surfaces together.
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #5 on: September 20, 2020, 09:09:46 pm »

I flew the plane tonight in perfect conditions, it climbs steadily with the 10mm motor and gearbox, not fast, but enough. On the glide it performs amazingly, almost looking as if it was hovering as it drifted slowly overhead. The undercambered wing is a good performer but has a downside I need to work on.... wing flutter, the leading edge flutters if you pick up too much speed while coming down, slowing down by levelling out cures it instantly, but I would like to stop it happening. My Elmira balsa glider did it even worse until I skinned the bottom of the undercambered wing, which doubled the wing weight but left me with an incredibly stiff wing that didnt flutter at all. I dont want to add as much as that to Floaty. The trailing edge bamboo is short, I may replace these with longer ones to try and firm it up a bit. I had thought about clear tape on the underside in strategic places, but the sticky side would pick up debris. Maybe just clear plastic strips taped on would stop that.
I am very impressed with the glide, myself and my friend have been considering home made folding props to help but the nose shape doesnt allow it on this one. To be honest, the prop doesnt seem to have much effect on the glide anyway. Then I flew my bigger jet, another of my successes, packed them in my 'Jetpack' and 'cycled' home when it was too dark to fly.
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JimG

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #6 on: September 21, 2020, 11:36:09 am »

Not sure what it would do to the aerodynamics and the glide but try cross bracing between the adjacent ribs. Trailing edge of one rib to leading edge of the next. Use bamboo strips and this should stiffen the wing without adding too much weight.
Jim
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #7 on: September 23, 2020, 11:23:57 am »

I had thought about using 1/32 x 1/8 balsa strips, as the bamboo is quite heavy compared to balsa. I need to do some weighing to see which method is lighter but still strong enough. I may just live with it and keep my weight at 78g. I know the problem so I can fly accordingly. Looks worse than its actual effects, that might just be until the wing ends up snapping? It glides amazingly as it is, I dont really want to mess with that, I seem to have ended up getting it right first time, well, close enough. 😁
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #8 on: November 10, 2020, 07:24:49 pm »

I got a message from youtube saying that the video I posted the link to above, has been age restricted but no reason given. There is no swearing? I dont know. Dont suppose it makes much difference.
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #9 on: November 29, 2020, 10:08:57 pm »

Floaty gets some floats. It copes fine with these pretty large floats. A slight increase in power up to 1/3 throttle was needed to let it cruise around at gentle speeds. Without the floats, it only needs 1/4 throttle. Float mountings are made from kebab sticks with paper clip fittings bound on with thread and superglued. Fiddly fiddly job but turned out pretty straight.
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JimG

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #10 on: November 30, 2020, 11:35:27 am »

Have you flown it off water yet? Take off from water is where extra power is most needed due to the extra drag from the water.
Jim
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Re: Floaty.. My 44inch span 78g motorglider
« Reply #11 on: November 30, 2020, 12:43:27 pm »

I got a message from youtube saying that the video I posted the link to above, has been age restricted but no reason given. There is no swearing? I dont know. Dont suppose it makes much difference.

It does matter as I can't see it. It tells me that I must login to see it as part of the age verification process. I view YouTube without logging in.
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #12 on: November 30, 2020, 01:23:48 pm »

I had a guy wanted to be a friend on youtube, said my video was cool, I googled him and found lots of messages saying he was a scammer, so I mentioned that in a message and never heard from him again. It looked to me like he added thumbs down to a few videos and that was that, I wonder if it was him that flagged it?
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #13 on: November 30, 2020, 01:25:41 pm »

I havent tried it off water yet, that will prove whether its a floatplane or just a boat. 😁
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #14 on: December 02, 2020, 01:51:40 pm »

Weight (including floats, struts, bands, dowels and 1.8g heavier battery) is now up to 116g, a fair increase but it copes really well, it will be interesting to see how it copes with taking off from the water. With the performance it has already, I am confident it will manage. The motor is actually 8.5mm, not 10 as I said before. This motor and gearbox unit has plenty of power so it should be fine.
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Andy M

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Re: Floaty.. My 44inch span 78g motorglider
« Reply #15 on: December 04, 2020, 03:54:54 pm »

It takes off from snow fine, just need to find a big meltwater puddle for a water test now.
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