[philipa_240sx]

Got a second flight in yesterday. Outdoors again in light winds (5-10km/h).

I put 8min on a single 350mAh battery with over 20% charge remaining after the flight. Once again, I was impressed at the authority of the V-tail at speed. It was easy to loop and turn within 5ft or less.

I have started to look at a conventional tail for indoors but I have to be careful of upsetting the CG. The components are rigidly mounted, with only the battery being adjustable.

[philipa_240sx]

A repeat of my post from "What is everyone flying?":

Gym-V... a gym sized version of the Parkzone Slo-V. The Slo-V is already advertised as an 'gym sized' plane to start with: PZ Slo-V advertisement.

It's 2/3rd's the size, almost 1/3 the weight, and has a bit lighter wing loading than the original. My goal was to create a lighter and hopefully more maneuverable version.

Specs:
- 76cm (30") WS, 20cm (8") chord, 4-40 under-cambered wing made from FFF
- Shortened fuse to 52cm (20.5") from 31.5" stock.
- Power Up Sport 250 BL motor (16g, 2300kv) from HeadsUpRC
- APC 5.7x3 prop
- 10A Power Up BL ESC from HeadsUpRC
- TP SG50 5g servo's with Du-bro hardware and 1.5mm CF pushrods
- 3mm depron V-tail
- Slo-V stock wing pylons, battery tray, modified stock motor mount, and V-tail brace.
- 0.047" music wire LG with 1.25" Du-bro wheels
- 350mAh 2S Lipo
- AUW is 165g (5.8oz).
- Wing loading: 17.17 kg/sqm or 3.52 oz/sqft

I'm just waiting for the correct prop to arrive (the orange GWS is for mock-up) and she'll be ready to maiden... well sort of. This is my second attempt at this build. The first had a GWS IPS 'A' drive and 9g servo's. It flew well but it was bit too fast and heavy... for indoors at least. It was also tail heavy which required placing the wing further back to get the correct CG. I felt this caused issues with rudder authority and maneuverability.

By using lighter components and being more careful with the build this time 'round, I've saved another 30-35g and was able to move the wing forward to where it should be.

[philipa_240sx]

Well, I finally got to maiden her and I was somewhat disappointed with the results...

I was at my usual indoor venue, a small gymnasium (60x100'). Normally I would maiden outdoors but the weather hasn't been co-operating. Admittedly this gym is a tight space to fly a 30" WS plane.

I got rid of the mock up orange prop and purchased a 5.7x3 APC prop which should have been ideal for this motor. She lifted off fine, but the response was just not there. I lacked enough speed or thrust and was on the verge of stalling in turns. I flew the same fuse but with a 33" wing, GWS IPS A drive and a 1047 prop a few months ago and the difference was night and day.

The motor is a bit of uncharted territory as little data exists for it. It's similar to the Turnigy/HXT C2222 but not as hot a wind: 2300kV vs 2850kV. The 5.7x3 prop should be enough for 5.5oz thrust and ~30mph according to the specs and motor calculator. I lack a test bench/jig so I cannot make any proper measurements.

I'm tempted to try higher pitch and/or larger diameter props. But keeping it below 4 amps as it already runs a bit warm.

[leopard1]

You could try the GWS 0843 prop. It would be almost in the middle of the 573 and the 1047.
Just a thought for you.

Good luck!

[cassat]

Yeah, I would try a 7 x 6 prop or 8 x 4 as Paul says also.

[adaptabl]

I had bad results with a "v" tail indoors. I think the speeds are too low to be affective. I took the same plane and added a conventional tail and the plane responded great. The only difference was the tail. With the "v" tail it would barely turn, changing to the conventional tail made the plane fly as well as some 4 channel planes. I would suspect you may have the same problem.

[philipa_240sx]

Originally Posted by adaptabl

I think the speeds are too low to be affective.... I would suspect you may have the same problem.

I was thinking this also. The plane becomes very mushy at low speeds. No rudder authority at all. The V-tail design was used on the Gym-Blu by Gene Bond over at RCG. My Gym-V is nearly identical in design. Your plane looks almost like the Gym-Blu?

I flew a Blu-Baby 33"WS with conventional tail in the same gym. As I remember it flew much better. I will fab up a conventional tail, but with more rudder and elevator area than my Blu-Baby and try again. What are the dimensions of your plane?

[adaptabl]

Originally Posted by philipa_240sx

I was thinking this also. The plane becomes very mushy at low speeds. No rudder authority at all. The V-tail design was used on the Gym-Blu by Gene Bond over at RCG. My Gym-V is nearly identical in design. Your plane looks almost like the Gym-Blu?

I flew a Blu-Baby 33"WS with conventional tail in the same gym. As I remember it flew much better. I will fab up a conventional tail, but with more rudder and elevator area than my Blu-Baby and try again. What are the dimensions of your plane?

It was a Gym-blue. I took the "v" tail and made it flat then added a rudder. Totally different flying airplane.

[philipa_240sx]

Originally Posted by adaptabl

It was a Gym-blue. I took the "v" tail and made it flat then added a rudder. Totally different flying airplane.

So you now have a H-stab that is approx 16"Wx6"L and a V-stab that is half that... so 8"x6"? Seems to make sense.

[philipa_240sx]

I maidened the Gym-V outside yesterday. Despite the chilly 15km/h winds I took a chance. A gentle toss and she climbed out straight and level. The CG seemed pretty well set. However the undercambered wing and light ~6oz AUW made her a handful. I think this would be a great little park flyer for small spaces... like ball diamond sized.


Indoors is another story...

I found the V-tail had alot of rudder authority, just like my Slo-V did. But it does not respond well at very low speeds and is quite prone to stalling. I suspect it's a combination of tight turns and the small prop I am using (5.7x3). Perhaps a geared drive with a big prop would give me more prop wash over the tail and added thrust? However I am close to the limit in prop size for this motor. I 'might' be able to squeeze a 7x3.5, but motor calcs show a huge penalty in efficiency and higher amp draw than my small 350mA Lipo's will allow.

I have another micro motor on order, an HXT 18-11 2000kV that I want to try. It should be able to handle a slightly larger prop. I will also fab up the T-tail and experiment some more.