P51 老野馬

身經百戰既3歲老野馬重生, 爆頭斷身掛樹,重組加上7x5e / 1800kv, Power 350W, 快
但重了100g, wing loading 大, 比零戰易失速很多

V22 VTOL 垂直起降 魚鷹式傾斜旋翼機

This is my VTOL maiden under gust of 20kph before the rainstorm.

My project takes me 2 weeks ( ~20 hours in total) , Most material fetched from my junk box..

Basic priniple:
Flight control similar to real V22, except in real V22 there is no swashplate .
Roll - Differntial pitch control, i.e. more positive pitch on one rotor provide extra lift to roll.
Yaw- Either swashplate tilted oppositely in forward/ backwack direction.
Pitch - Both swashplate tilted in same direction either forward/ backward. The C.G. of the craft has significant effect on the pitch axis.
Transition - Operate by a strong metal gear servo that tilt the both rotor forward from vertical position.
Bothe swashplates governed by TH2 tandem control board from techproduct.

Materials:
1) 2 Trex 450/ Clone rotor head
2) 2x Trex SE frame (I made one from 0.8mm fiberglass board with a dremel), 6 CCPM servos
3) Rotor transition tilting by 5mm copper tube, being attached firmly to the Trex frame at 90 degree.... photo
3) Trex tail boom x 2, with bearings at each end, holding the inner 5mm copper tube
4) Copper tube has a ball link screwed on it can link to the 82 MG pod tilting servo.
5) 2 Towerpro 2409, 1500kv brushless, @ 15T x 4s, Headspeed 2100 rpm
6) 4s 220mAh, with 2 18A ESC. UBEC 3A.
7) 325 blades cut down to 260mm size, for scale down to adopt to my crappy T34 mentor fuselage of 800mm long. ( I will definitely scaleup to use 325mm blades for a 100mm long fuselage)
8) Roll axis gyro : Esky 802? , Yaw axis gyro - Align 500 , channeled to have remote gain control.

Mechanical setup:
1) Both rotor must have the blades well balanced. Swashplate and servo centered and trimmed as in a heli.
2) The most difficult part is to solve the vibration ./ resonance issue. Half of my time is to figure out where the vibration comes from. Since the 5mm copper tube takes all the vibration and will shear itself . The answer is use the strongest material/ method to ancho the copper tube.
3) To neutralize the change in CG during transition and the rotor is heavy, and will shift the CG forward on forward flight. So selecting a point to attach the copper tube is essential.
4) Pitch axis does not need gyro as the low CG will stabalize it self.

Electronic setup:
1) TH2 ..... setup... This makes me mad as the Ch6 (transition switch control, this is essential as it deactivate the roll/ yaw gyro, which is wrong when the pod is tilted) is not working with my DX7. Eventually I flash the firmware and it works like charm.


........

Since I cut down 2 pairs of 325 wooden blade to 260mm, I dare not stress the blade too much HS. Now geared at 15T/4s/1500kv towerpro motor (probably 1200kv), with HS of 2100. I am sure I need more HS ,say 2400, with 260mm blades. The wings did eat up lots of thrust, as it hovers much better when without wings, inside my room. I will try 315mm blade, or 16-17T if I can find somewhere (Align largest 0.5M pinion is 15T).

Hovering current 15A only.

Collective pitch with cyclic control is much more stable in hovering mode.

Cutting down 335mm to 260mm wooden blade.

Essential to make the jole perpendicular to the chord

EDF 推力計

55 EDF , thrust 300g @ 23A/ 10.5V.

Without a pitch speed measured, it is difficult to comment the efficency of different EDF. GWS EDF gives high thrust but lower pitch speed.

零戰

Bought 2 years ago for HKD 170

All painted and RTF

Motor mount from Align Trex600 aluminium rod

40A himodel ESC HKD$99; so cool that no heat sink required.

The CG is very forward located ~2cm behind leading edge.

Flies much better than P51; can fly very slow without stalling. High speed flying is no problem , especailly with 8x6 3 blades propeller.

3s @ 20A

I tried APC8x8 which is even better, but the current takes as high as 33A.

August-08: Now use APC 7x5e which is more gentle to my Radar cheap lipo. Motor : Emax 2215-25 1500kv?

油機內置點火

The Align 2 in 1 ingition board is good but is expensive ~$HKD230.

I DIY a simple connection to deliver 1.5V @ 3-4A to charge the glow plug.

The power source is from a 2S 2200mAh Lipo. It supplies 5V to the BEC. One cell of the 2S lipo is step down from 4V to 1.5V through 3 diodes rated 3A, in series. Since the glow plug only fires a few seconds, efficency is not a problem at all.

P51 1460mm Wing Span

The World Models .46 P51 Mustang. This is a rather old version but seems I cannot search too much information about the flying character of this bird.
Weight 2.5-2.7kg
Wing Span 1460mm
Engine : OS50SX-H, retired from my Trex600N; as the cylinder head is heavily damaged by the broken ring (after difficult starting ). Replacement of the cylinder head cost 1/3 of a new Os50. In addition, the hex screw slipped and resulted in brutal jigsawing to open up the cylinder head. So I decided to use in on a plane.

BUILDING:
The kits include all you needs. The retractable landing gears are excellent, though the wheel cover is too thin and will break easily. In addition the coverings tend to be peeled off easily as the wheel may rub against the depression.

FLYING CHARACTER:
Amazing, this bird flies excellent with reasonable speed at APC 11 x 8 . Tachospeed reads maximum rotation at 11,500 (wasn't this lower than expected?) only at half turn needle valve.

Needle valve needs a 3 inches piano wire connected with a wheel locknut to make it easier to be tuned.

The Flaps are aileron mixed and not efficient as an independent flap. Flying in typhoon signal 3 shows the strong built of this bird. The bird will wag funny under gust of 60 kph. Landing is easy even in gust.

Stalling is not easy and there are plenty of climb power with the OS50. Looping is a piece of cake.

I plan to convert it to electric Warbird soon as I am sick with the oily film that may stain my car cabin.


6-2008 :
Finally retired after a heavy crash resulted from stall turning before landing. Main wing is intact but body detroyed.