electric 1.8m glider
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Protech Alpha 180 V2
electric 1.8m glider |
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2003.12.24
This is a very nice 1.8m electric glider built by Protech.
Wing is balsa sheeted D-box with transparent film cover. Central panel is flat and has two removable wingtips that make up the polyhedral. Wingspan is 180cm.
Fuselage is injected plastic. Tailfeathers are balsa with transparent film, fixed to the fuse with two bolts for easy removal.
The glider can be stored back to it's original box which is very nice for transportation, but in the day-to-day use I prefer to keep the wings and tailfeathers assembled, so I only have to attach the wing to the fuse to go flying.
I equipped it with 2 Hitec HS-81 servos, a Protech 35A ESC (actually a Jeti 35 relabeled) and a Hitec Electron 6 receiver. I've also used Berg receivers in it but later moved the Berg to my smaller planes since the Electron 6 was too large for them.
These pictures above show the original 8*4 prop installed, direct driven by the 540-type motor. The climb in this configuration is marginal... I only flew it once this way and didn't like it at all!
Later I fitted an MPJ-8053 planetary 3.33:1 gearbox and a Graupner CAM 13*7 folding prop, and got very decent performance from this setup.
The inline gearbox fits very easily to the fuse as can be seen below. I only had to do minor plastic surgery (literally, since the motor mount is plastic :-) to get it installed.
AUW is 1250g (=44.1oz) with Protech's original 7 sub-C cells 1900mAh 350g battery pack. I plan to use an 8 cell KAN 950 battery pack that at around 170g will drop the ready to fly weight to close to 1.1kg (=38.8oz).
On 2003.12.12 I took it to a nearby park called Villa Lobos for some flights with my friend Eric. That was the first flight with the GB + 13*7 prop. Climb was ok at first but after a 15-20sec motor run I heard it failing so I started to go around to land immediately. After the first 180 deg turn the motor went off completely and moments after the controls stopped responding. My concearn turned into desperation as I turned into a spectator to the glider's solo flight...
It went over some trees heading to the Marginal Pinheiros, a very very busy avenue close by. It wasn't very high so maybe it'd never have reached the park border, but luckily a gust took it into a spiral and it fell behind the trees.
It took me and Eric more than an hour to find it. It had made a perfect landing (better than the ones when I was in command :-) in a grassy field.
I never came to know what was the reason for that... I haven't noticed much radio interference when flying my Slow Stick with a very similar Berg rx earlier this day at the same spot. After cereful examination I took this same setup to fly same days later and it performed perfectly well.
2004.01.29
Changes:
Flies very very well, 3-4 climbs per charge in this configuration, floats very well with the reduced weight.
After landing it on the beach a couple of times I got tired of cleaning the sand out and decided to hand catch... made it on the first try! I come in low, when it's 15-20m away from me it's already at only 50cm from the ground but still coming in hot... I maintain this altitude bleeding some speed and energy and pull up when it's around 5m away from me... I try to grab it by the fuse with my left hand while walking backwards some 3 or 4 steps so to lessen the impact, further on I started grabing it by the leading edge but decided that by the fuse feels better.
2004.02.08
The more I fly this glider, the more I like it. Lately, from my fleet, this is the plane I find myself more often looking forward to have up in the skies.
The fact that it can be unassembled into a box around 95*30*10cm large also plays a big part in that. I really like how transportable it is.
I know it's a pretty basic and even cheap glider, which design and construction techniques don't came even close to the more advanced ones, but still it flies very well, stays up in the air very easily and is just plain fun and relaxing.
2004.02.15
Flew it for the first time with a camera attached for AP. Camera was an Aiptek PocketCam Slim 3000F stripped down of it's casing coming in at 41g (very light), taped to the side of the fuse. Worked great, pictures taken with it are the ones from this set with the wing showing on the top.
2004.03
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Took the Alpha-180 to a trip to Argentina with stops in Buenos Aires and Bariloche.
The possibility of storing it in a small box for travel was the deciding factor for me to choose this plane for the trip.
While we were there I took several aerial photographs from Buenos Aires' Palermo park and from Bariloche's Cerro Catedral. It was a pity the strong winds didn't cooperate while in Bariolche but the pictures from Buenos Aires came out very good. |
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2004.04.25
The Alpha is grounded since I started flying the Onion. It's somewhat similar in goals but the Onion is far superior.
I took off the heavy speed-550 power system and sold it, and have been toying with the idea of putting a much lighter motor in it to make it a real floater, but the hangar queue hasn't let me start working on this yet... too many projects, too little time!
2004.10.09
Here it is with the lighter power system:
This setup is turning the prop at 3800 rpm, which gives a 330g static thrust. Climb is a steady 20 deg angle, which is more than enough for my purposes.
AUW is now 770g but the CG is too far back and consequently the flight is unstable... I hope to lower the AUW and bring the CG forward by working on the tail feather servo linkage, which is very heavy stock as it is.
2005.02.12
I did something I had long wished to do... the Alpha-180 flew with a GPS on board!
(click for more)
