Skyraider Mach II CG?
07-19-2006, 09:37 PM
#1
Senior Member
Thread Starter
Join Date: Jul 2005
Location: , TX
Posts: 242
Likes: 0
Received 0 Likes
on
0 Posts
Skyraider Mach II CG?
I bought a The World Models Skyraider Mach II nib less manual. It's together, and the only pieces I had left over were replaced (throttle pushrod replaced with 2-56 to prevent metal-to-metal contact at engine). Anyone have the recommended control throws and CG for this airplane?
Thanks,
Smokin'
Thanks,
Smokin'
07-19-2006, 11:48 PM
#2
Member
Join Date: Jun 2004
Location: Redondo Beach,
CA
Posts: 31
Likes: 0
Received 0 Likes
on
0 Posts
RE: Skyraider Mach II CG?
The control throws for the Mach II are rudder 20mm, elevater 15mm, aileron 6mm. The C.G. is 85mm behind the leading edge.
Hope this helps.
Hope this helps.
07-20-2006, 09:34 AM
#4
Senior Member
Join Date: Jul 2002
Location: Sandy, OR,
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
RE: Skyraider Mach II CG?
I have had one of these ready to go for almost a year now, and it just sits collecting dust.
Maybe next weekend I can finally try it out. Too busy most weekends.
Let us know how it goes when you maiden it.
Maybe next weekend I can finally try it out. Too busy most weekends.
Let us know how it goes when you maiden it.
07-24-2006, 06:54 PM
#5
Senior Member
Thread Starter
Join Date: Jul 2005
Location: , TX
Posts: 242
Likes: 0
Received 0 Likes
on
0 Posts
RE: Skyraider Mach II CG?
Maidened the Skyraider yesterday.
First, the set-up:
A Futaba S3003 servo was used on the ailerons, Hitech HS425s elsewhere. I replaced the throttle pushrod, tube, and connector with a 2-56 and tube with a plastic clevis to avoid metal-to-metal contact at the throttle arm. Other than that, and the installation of a GP switch/charge jack, the plane was assembled with all the supplied components. A Hitech 600mah ni-cad and Supreme receiver were installed, and the plane balanced perfectly according to the Great Planes (GP) CG Machine at 85mm behind the leading edge with the receiver in front of the servo tray and the battery behind. No additional weight was used for balance.
A Tower Hobbies .46 and 11x6 APC with a GP 2.5 spinner with aluminum backplate (my preference) was used for power, and it is way more engine than this airframe needs. The engine was installed as far forward as possible on the supplied mount. The slots where the mount bolts to the firewall were elongated to allow more width between the rails to fit the crankcase. An APC 11x6 prop was chosen as it is the lowest pitch prop recommended for break-in. The engine could spin this at 11,700rpm running rich enough to leave an easily visible smoke trail. This engine only had two tanks of fuel run through it before the first flight, so it isn't even broken in yet.
On to the maiden:
Wind was NE 8 gusting to 15 or so on a N/S grass runway. Temp was mid 90s F, relative humidity about 25%. Ground handling was very good. The elevator had sufficient authority to keep the tail firmly planted in cross-winds, a difficult proposition considering our rough, drought-stricken runway. Ease the throttle up, ease the elevator to neutral, and the Skyraider tracked straight down the runway with no correction. It was airborne with a 75-foot run, at about 1/3 throttle. YIKES! What a squirrel! Throttle management required! The Skyraider flew at a good clip at 1/4 throttle. The checkerboard pattern on the covering turns ash gray at a distance, and perfectly blends into North Texas smog. She'll disappear in a blink.
First, a GP CG Machine was used to set the CG at 85mm, and it came out flying a little tail-heavy. This is the third plane on which the CG machine was used as designed, and all came out tail heavy. Do not trust the rulers. The CG was reset on the spar, which is 85mm behind the leading edge as measured along the top surface of the wing. The rulers on the CG Machine place the CG 5mm further back. Lesson to be learned: Toss the rulers. Measure along the wing surface and mark the CG. Then place the airplane on the CG machine to balance.
Second, the control throws listed above are high rates, at least for me since I've only been flying RC for a year. The Skyraider will rip the sky at speed with the rates listed above. I had 60% programmed on low rates, and that is enough for anything less than hot-dogging. Lucky enough to avoid the ground after take-off, once a little altitude was gained, flipping to low rates partly tamed the wild handling.
Third, when the right stick was returned to neutral from one direction, the servo wouldn't quite return to neutral, and the plane would continue a slow roll to the left. The servo problem was masked by the already wicked handling until the second flight. To be fair, the Futaba S3003 servo used on the ailerons has had a long career on combat SPADS. It's definately been banged a few times
After a couple very squirrelly patterns I was able to hand the transmitter to a master pilot who was able to get the plane back on the ground. Ah, the benefits of being a member of a good club!
Back on the ground safely (PHEEEEWWW!!!), some changes were made. The battery was repositioned on top of the receiver just in front of the servo tray. Foam was placed in front of the battery and receiver to keep those components in place. Aileron and elevator deflections were reduced as much as possible by repositioning the pushrods all the way in on the servo arms. The screw-adjust tabs on the control arms were already all the way out.
The Skyraider flew much better the second time, but elevator response was still a bit touchy. The problem servo quickly became apparent. Vertical is excellent, but not unlimited, with nice, 200-foot diameter loops possible with good throttle management. Two clicks up elevator and five clicks right aileron, and the plane would fly the 500-foot runway hands-off, even when buffeted by turbulance. Very nice. The engine may need a bit of down thrust since she tended to raise her nose slightly with power. Inverted flight required just a touch of down elevator. Rolls were almost axial, requiring just a hint of down elevator during the inverted portion. I expect the Skyraider will become more neutral handling with a little down thrust.
The second flight was short, 5-6 minutes. The engine, running at 1/4 throttle unless in a vertical attitude, simply didn't provide enough pressure to the tank to raise the fuel to the carb. The deadstick came on a go-around attempt. After a long, slow approach, moving the stick forward from idle leaned the engine and she quit cold. The Skyraider floated quite nicely, held just off the tall grass with increasing elevator until she just quit flying and plopped gently down. No bad low speed handling. No damage.
Back in the hanger, the faulty aileron servo has been replaced with a new Hitech HS425 to match the rest of the set. The elevator now has a longer control arm to tone it down. A hole will be cut in the right cowl cheek and the engine will be rotated 90* to solve the fuel flow issues. A 12x5 APC sport prop will be installed. Flourescent yellow and purple trim will be applied to increase visibility. Weekend forecast is 102*F, sunny, winds from the south at 10mph. Perfect!
First, the set-up:
A Futaba S3003 servo was used on the ailerons, Hitech HS425s elsewhere. I replaced the throttle pushrod, tube, and connector with a 2-56 and tube with a plastic clevis to avoid metal-to-metal contact at the throttle arm. Other than that, and the installation of a GP switch/charge jack, the plane was assembled with all the supplied components. A Hitech 600mah ni-cad and Supreme receiver were installed, and the plane balanced perfectly according to the Great Planes (GP) CG Machine at 85mm behind the leading edge with the receiver in front of the servo tray and the battery behind. No additional weight was used for balance.
A Tower Hobbies .46 and 11x6 APC with a GP 2.5 spinner with aluminum backplate (my preference) was used for power, and it is way more engine than this airframe needs. The engine was installed as far forward as possible on the supplied mount. The slots where the mount bolts to the firewall were elongated to allow more width between the rails to fit the crankcase. An APC 11x6 prop was chosen as it is the lowest pitch prop recommended for break-in. The engine could spin this at 11,700rpm running rich enough to leave an easily visible smoke trail. This engine only had two tanks of fuel run through it before the first flight, so it isn't even broken in yet.
On to the maiden:
Wind was NE 8 gusting to 15 or so on a N/S grass runway. Temp was mid 90s F, relative humidity about 25%. Ground handling was very good. The elevator had sufficient authority to keep the tail firmly planted in cross-winds, a difficult proposition considering our rough, drought-stricken runway. Ease the throttle up, ease the elevator to neutral, and the Skyraider tracked straight down the runway with no correction. It was airborne with a 75-foot run, at about 1/3 throttle. YIKES! What a squirrel! Throttle management required! The Skyraider flew at a good clip at 1/4 throttle. The checkerboard pattern on the covering turns ash gray at a distance, and perfectly blends into North Texas smog. She'll disappear in a blink.
First, a GP CG Machine was used to set the CG at 85mm, and it came out flying a little tail-heavy. This is the third plane on which the CG machine was used as designed, and all came out tail heavy. Do not trust the rulers. The CG was reset on the spar, which is 85mm behind the leading edge as measured along the top surface of the wing. The rulers on the CG Machine place the CG 5mm further back. Lesson to be learned: Toss the rulers. Measure along the wing surface and mark the CG. Then place the airplane on the CG machine to balance.
Second, the control throws listed above are high rates, at least for me since I've only been flying RC for a year. The Skyraider will rip the sky at speed with the rates listed above. I had 60% programmed on low rates, and that is enough for anything less than hot-dogging. Lucky enough to avoid the ground after take-off, once a little altitude was gained, flipping to low rates partly tamed the wild handling.
Third, when the right stick was returned to neutral from one direction, the servo wouldn't quite return to neutral, and the plane would continue a slow roll to the left. The servo problem was masked by the already wicked handling until the second flight. To be fair, the Futaba S3003 servo used on the ailerons has had a long career on combat SPADS. It's definately been banged a few times
After a couple very squirrelly patterns I was able to hand the transmitter to a master pilot who was able to get the plane back on the ground. Ah, the benefits of being a member of a good club!
Back on the ground safely (PHEEEEWWW!!!), some changes were made. The battery was repositioned on top of the receiver just in front of the servo tray. Foam was placed in front of the battery and receiver to keep those components in place. Aileron and elevator deflections were reduced as much as possible by repositioning the pushrods all the way in on the servo arms. The screw-adjust tabs on the control arms were already all the way out.
The Skyraider flew much better the second time, but elevator response was still a bit touchy. The problem servo quickly became apparent. Vertical is excellent, but not unlimited, with nice, 200-foot diameter loops possible with good throttle management. Two clicks up elevator and five clicks right aileron, and the plane would fly the 500-foot runway hands-off, even when buffeted by turbulance. Very nice. The engine may need a bit of down thrust since she tended to raise her nose slightly with power. Inverted flight required just a touch of down elevator. Rolls were almost axial, requiring just a hint of down elevator during the inverted portion. I expect the Skyraider will become more neutral handling with a little down thrust.
The second flight was short, 5-6 minutes. The engine, running at 1/4 throttle unless in a vertical attitude, simply didn't provide enough pressure to the tank to raise the fuel to the carb. The deadstick came on a go-around attempt. After a long, slow approach, moving the stick forward from idle leaned the engine and she quit cold. The Skyraider floated quite nicely, held just off the tall grass with increasing elevator until she just quit flying and plopped gently down. No bad low speed handling. No damage.
Back in the hanger, the faulty aileron servo has been replaced with a new Hitech HS425 to match the rest of the set. The elevator now has a longer control arm to tone it down. A hole will be cut in the right cowl cheek and the engine will be rotated 90* to solve the fuel flow issues. A 12x5 APC sport prop will be installed. Flourescent yellow and purple trim will be applied to increase visibility. Weekend forecast is 102*F, sunny, winds from the south at 10mph. Perfect!
