As you can see plane have few updates and modifications in construction. Two main new things are : CD-R engine and propeler.
From testing on the ground i must say custom CD-R engine and Mamo Upsidedown propeler is better combination than DW8/18 and T-Rex tail blades. Propeler and engine almost make no noise, what make plane acceptable for F3P-AM competitions.
Aerodynamic devices
As you see in Arrow video it fly pretty good without any aerodynamic devices, but still i want update plane stability on low speed, rolling circles and
KE characteristics. So i
tested few different
SFG combinations on first Arrow.
On V2 Arrow i add SFG's (first picture) that worked best on first Arrow, these SFG are inventions of
Jan Spatny and
David Kyjovky Czech top indoor pilots.
Difference in flying characteristics with
SFG's and without them is huge ! Now Arrow fly like biplane! Rolling circles are piece of cake also knife edge loops and rolling loop in gym with ~9m ceiling is no problem. One negative side of these
SFG's, they make snap and point rolls little slower, and that's not very good for freestyle.
Propeller and engine
There is no questions that VPP is difficult and new thing for many indoor pilots. Success depends on what equipment you will pick reliable and easy to setup system should be main criterions by picking up new VPP for your planes. My suggestion take a good look to Mamo models UpsideDown propeller. It is designed by well known world class indoor pilot Martin Muller, i must say this prop is piece of art! No vibrations, easy assembly, two sets of great flexible (8 and 9 inch) blades. Believe me to have such blades is very important when you hit flour with running engine.
Even if this propeller is not cheap ( 50 eur), i think it is very good investment. If compare this prop with standard tail rotor blade VPP, it can hold much bigger impacts. Just want to say after first impact with old prop when it was mounted in front of airplane, i had to buy 20$ replacement parts... Besides when you hit flour with regular middle shaft VPP prop, you also will have to change pitch servo gears, with upsidedown prop construction even smallest servo can handle impact with no damage!
Custom CD-R engine and fiberglass motormount.
This engine is made by my good friend Vytas, engine have 9 pole stator, 25g weight with motormount and wires. Will give more specs affter test flights.
Build them light
It is not secret that lighter planes fly much better. Specially you can fell this in indoor , low wing loading is key to great flying machine. Here are few tips how i save weight on new Arrow:
- Use lighter equipment you can get!
- Use small amount of light glues, thin CA is best option.
- Try to find battery/engine/esc system that will work on small 2S lypo packs, overall 2s packs are much better than 3s packs:)
- Do not use sticky tape hinges! They add at least 1-2g on your plane, beside sticky tape hinge are ot reliable! They can fail during some "hard flying". I try to use on all my indoor planes "floppy disc" hinges, it is light and very durable and most important give you precise control !
- Lightening holes in fuselage, air brakes holes on eileron elevator and rudder, together all these lightening's remove 2-3g from plane, but be careful don't use this to much it can make airframe fragile.
- Don't use regular landing gear with wheals, lighter and much easier to build option is EPP "wheellpant" imitation.
- Make shorter all unwanted wires, with good work you can save ~5g.
- If you building monoplane use only one flat carbon piece in middle of wings, to reinforce construction use, thin fishing line.
- If you building bipe do not use flat carbon reinforcement on wings at all.
- Use Pull-pull on rudder and elevator instead of pull-push.
Building Arrow V2.
I use Waypoint 060bb servos all over my plane, during 3 years of indoor flying i found that these servos are probably best option for indoor planes, i had ~20 of these servos, and none of them fail during long and hard flying. Construction of these servos let us remove back case of these servos (it is only to protect servo from dust and other things that can couse damage. One case is 0.6g one 4 ailerons it is already 2.4g!
Lightening holes in fuselage, air brakes holes on aileron elevator and rudder, together all these lightnings remove 2-3g from plane.Thanks to new prop, engine and lighter/clean building new arrow will be ~170g RTF, that's 20g lighter than first Arrow, this will give longer flying time and better flying characteristics. in this case 20g is 10% of total plane weight !
More after test flight...
