Skymaster F18F c of g position
#51
RE: Skymaster F18F c of g position
Hi Millsy,
Lighting system is from electrodynamics, compact and light. Have not tried full length camber change....don't think it needs it as it will land slowly enough as it is. The elevator mod is critical I reckon....have done it with all of my skymaster kits. To swing a huge stab like that off a 23mm long control arm is not a good idea, particularly when there is room for almost twice that length.
BTW, if you have dialled your dual rates right down you will not be losing resolution, only compressing it over a reduced range. If you dial down your ATV, then you are losing resolution over your final servo travel, because your are trimming off the ends of the travel. That's why the gyro manufacturers tell you to set your ATV to 100% no matter what, and reduce your servo travel by reducing your dual rates. Anyway, irrespective of any of that, it is prudent to apply the best mechanical arrangement possible.
Here is an example of what I did on my 1/6 F16 ...did the same thing on all of my other jets too and makes me a lot happier about hauling on the thing
Good luck with your F18.
Regards,
Craig.
ps. will say hi to Mike for you.
Lighting system is from electrodynamics, compact and light. Have not tried full length camber change....don't think it needs it as it will land slowly enough as it is. The elevator mod is critical I reckon....have done it with all of my skymaster kits. To swing a huge stab like that off a 23mm long control arm is not a good idea, particularly when there is room for almost twice that length.
BTW, if you have dialled your dual rates right down you will not be losing resolution, only compressing it over a reduced range. If you dial down your ATV, then you are losing resolution over your final servo travel, because your are trimming off the ends of the travel. That's why the gyro manufacturers tell you to set your ATV to 100% no matter what, and reduce your servo travel by reducing your dual rates. Anyway, irrespective of any of that, it is prudent to apply the best mechanical arrangement possible.
Here is an example of what I did on my 1/6 F16 ...did the same thing on all of my other jets too and makes me a lot happier about hauling on the thing
Good luck with your F18.
Regards,
Craig.
ps. will say hi to Mike for you.
#52
RE: Skymaster F18F c of g position
Cheers for that, nice bit of sheety work there, lol
You probably have done so already, but I will let Skymaster know about these mods.
You probably have done so already, but I will let Skymaster know about these mods.
#53
RE: Skymaster F18F c of g position
Thanks Millsy. The extension arm in the above photo is off at an angle to compensate for the fact that the flats on the stab pivot rods were ground at different angles and I set this one up to get the ball link at the same location in relation to the pivot stab. Fixed two problems with one piece of ali!
I have not sent this to skymaster....guess I figured that my input would not really have mattered and was just happy to do my own thing. It sure makes the stabs a lot more solid with far less slop. Have done this mod on all of my skymaster jets. Feel free to let them know Millsy.
Craig.
I have not sent this to skymaster....guess I figured that my input would not really have mattered and was just happy to do my own thing. It sure makes the stabs a lot more solid with far less slop. Have done this mod on all of my skymaster jets. Feel free to let them know Millsy.
Craig.
#54
RE: Skymaster F18F c of g position
I sent them an email today, also with a link to this thread.
With the resolution, that is actually what I meant, like you said. The servo resolution is at 100% but the linkage ratio amplifies the resolution, making it physically worse than what is set on the radio, which of course amplifies all the slop as well.
With the resolution, that is actually what I meant, like you said. The servo resolution is at 100% but the linkage ratio amplifies the resolution, making it physically worse than what is set on the radio, which of course amplifies all the slop as well.
#55
RE: Skymaster F18F c of g position
Hope you don't mind me bringing this back from a bit from in the past, but mine was shelved for a long time due to work and other factors.. I also had to replace the original right stab as the shaft was sloppy in the stab. I'll peel back the bottom and examine it, and rebuild it as a possible spare if I ever need it. I definitely think there is a serious lack of hornet threads around here lately. :-)
I have it set up with every servo linkage at the closest holes on the arms and atv's all set at 100%, and at high rates (100%) I am getting the recommended throws, so I'm pretty happy with that. Just now setting up my cg and after reviewing a lot of posts, I set it up for 130mm. I originally had set it up for twin batts, via regulators to a Smart Fly Expander board. Well, i ditched the regulators and nimh packs in favor of direct hook up with twin large capacity LiFe packs. To balance as it is here in the pic, I only needed 16.6 oz of battery on the nose. Just need a tad more to level her out. No dead weight required. The scale cockpit and pilot helped with that...nice!
Tomorrow I'm doing run ups and taxi tests to check the brakes and nose/gyro steering, etc. Hopefully to maiden later this spring/summer.
I have it set up with every servo linkage at the closest holes on the arms and atv's all set at 100%, and at high rates (100%) I am getting the recommended throws, so I'm pretty happy with that. Just now setting up my cg and after reviewing a lot of posts, I set it up for 130mm. I originally had set it up for twin batts, via regulators to a Smart Fly Expander board. Well, i ditched the regulators and nimh packs in favor of direct hook up with twin large capacity LiFe packs. To balance as it is here in the pic, I only needed 16.6 oz of battery on the nose. Just need a tad more to level her out. No dead weight required. The scale cockpit and pilot helped with that...nice!
Tomorrow I'm doing run ups and taxi tests to check the brakes and nose/gyro steering, etc. Hopefully to maiden later this spring/summer.
#56
Senior Member
RE: Skymaster F18F c of g position
ORIGINAL: Sparhawk
Hope you don't mind me bringing this back from a bit from in the past, but mine was shelved for a long time due to work and other factors.. I also had to replace the original right stab as the shaft was sloppy in the stab. I'll peel back the bottom and examine it, and rebuild it as a possible spare if I ever need it. I definitely think there is a serious lack of hornet threads around here lately. :-)
I have it set up with every servo linkage at the closest holes on the arms and atv's all set at 100%, and at high rates (100%) I am getting the recommended throws, so I'm pretty happy with that. Just now setting up my cg and after reviewing a lot of posts, I set it up for 130mm. I originally had set it up for twin batts, via regulators to a Smart Fly Expander board. Well, i ditched the regulators and nimh packs in favor of direct hook up with twin large capacity LiFe packs. To balance as it is here in the pic, I only needed 16.6 oz of battery on the nose. Just need a tad more to level her out. No dead weight required. The scale cockpit and pilot helped with that...nice!
Tomorrow I'm doing run ups and taxi tests to check the brakes and nose/gyro steering, etc. Hopefully to maiden later this spring/summer.
Hope you don't mind me bringing this back from a bit from in the past, but mine was shelved for a long time due to work and other factors.. I also had to replace the original right stab as the shaft was sloppy in the stab. I'll peel back the bottom and examine it, and rebuild it as a possible spare if I ever need it. I definitely think there is a serious lack of hornet threads around here lately. :-)
I have it set up with every servo linkage at the closest holes on the arms and atv's all set at 100%, and at high rates (100%) I am getting the recommended throws, so I'm pretty happy with that. Just now setting up my cg and after reviewing a lot of posts, I set it up for 130mm. I originally had set it up for twin batts, via regulators to a Smart Fly Expander board. Well, i ditched the regulators and nimh packs in favor of direct hook up with twin large capacity LiFe packs. To balance as it is here in the pic, I only needed 16.6 oz of battery on the nose. Just need a tad more to level her out. No dead weight required. The scale cockpit and pilot helped with that...nice!
Tomorrow I'm doing run ups and taxi tests to check the brakes and nose/gyro steering, etc. Hopefully to maiden later this spring/summer.
#57
Hi Guys,
Any recent updates on skymaster F18F build up and flights? I will get mine in a couple of weeks i assume and although i found some threads they are old by 6-7 years and was wondering if skymaster has made any changes to recommendations from people in this thread and if anybody purchased one in 2013 and has flown it so we can share any info that at least is recent and maybe more valid.
Any recent updates on skymaster F18F build up and flights? I will get mine in a couple of weeks i assume and although i found some threads they are old by 6-7 years and was wondering if skymaster has made any changes to recommendations from people in this thread and if anybody purchased one in 2013 and has flown it so we can share any info that at least is recent and maybe more valid.
#58
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Hi Guys, thanks for the encouraging dialog. I don't normally post, but I nearly lost a pair of boxers and an F-18F in Blue Angel colors a few hours ago. My friend in Houston has the same bird (different colors) and our setup is identical, his flys very well. On my first flight, the plane rotated and went pure vertical on rotation. The manual (as you're aware) states that a CG between 160 and 140 is "ok"...so I moved the CG from 155 up to 141. Flight two, same exact personality....rotation and uncommanded pitch to vertical. The pitch was so sensitive that I flew the balance of the flight using elevator trim only. What a wild ride. Even with a stable approach, I had a poor landing and am writing John for parts prices. What a day... I'm glad I'm not the only one with this event - been flying RC 40 years, and my garage of Skymaster planes all fly awesome. Take care - be safe out there.
#59
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Yes,shifting the cg back will help rotation,.. In Basimps video you can watch him kicking quikly and returning back to almost neutral position almost at once on takeoff.. not everybody can do this ! Taking off with flaps like Ravill and many people also recommends turns this takeoffs into a non-issue. even with a less sensitive, aft CG.
I also remembered a thread of a F-18 doing the "jump" from a pilot of singapore from some years ago.. impressive pictures and a good save:
http://www.rcuniverse.com/forum/rc-j...l-takeoff.html
This was written before Dr.Honda maiden jet flight.(!)
I also remembered a thread of a F-18 doing the "jump" from a pilot of singapore from some years ago.. impressive pictures and a good save:
http://www.rcuniverse.com/forum/rc-j...l-takeoff.html
This was written before Dr.Honda maiden jet flight.(!)
#60
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Hi Guys, thanks for the encouraging dialog. I don't normally post, but I nearly lost a pair of boxers and an F-18F in Blue Angel colors a few hours ago. My friend in Houston has the same bird (different colors) and our setup is identical, his flys very well. On my first flight, the plane rotated and went pure vertical on rotation. The manual (as you're aware) states that a CG between 160 and 140 is "ok"...so I moved the CG from 155 up to 141. Flight two, same exact personality....rotation and uncommanded pitch to vertical. The pitch was so sensitive that I flew the balance of the flight using elevator trim only. What a wild ride. Even with a stable approach, I had a poor landing and am writing John for parts prices. What a day... I'm glad I'm not the only one with this event - been flying RC 40 years, and my garage of Skymaster planes all fly awesome. Take care - be safe out there.
Check to see if your friends has a different AoA when its sitting on the ground. From what I found with my Feibao F18F if it has a negative AoA on the ground when it builds up speed it tends to push the nose down on takeoff which means you have to use a fair bit of elevator to make it unstick which generally causes the F18 to take off at a high angle, most R/C F18 pilots suggest a fair amount of flap on take off. Plus you actually hold elevator in until it builds up speed on the ground and the nose becomes lighter then relax the elevator a little. You can try adding a spacer plate between the front retract and mount to increase the AoA slightly as well.
Hope it helps.
#61
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Hi Guys, thanks for the encouraging dialog. I don't normally post, but I nearly lost a pair of boxers and an F-18F in Blue Angel colors a few hours ago. My friend in Houston has the same bird (different colors) and our setup is identical, his flys very well. On my first flight, the plane rotated and went pure vertical on rotation. The manual (as you're aware) states that a CG between 160 and 140 is "ok"...so I moved the CG from 155 up to 141. Flight two, same exact personality....rotation and uncommanded pitch to vertical. The pitch was so sensitive that I flew the balance of the flight using elevator trim only. What a wild ride. Even with a stable approach, I had a poor landing and am writing John for parts prices. What a day... I'm glad I'm not the only one with this event - been flying RC 40 years, and my garage of Skymaster planes all fly awesome. Take care - be safe out there.
Are you using the same engine power as your friend?...if less.. you might have a modified your AOA from the nose gear.
#63
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Yes,shifting the cg back will help rotation,.. In Basimps video you can watch him kicking quikly and returning back to almost neutral position almost at once on takeoff.. not everybody can do this ! Taking off with flaps like Ravill and many people also recommends turns this takeoffs into a non-issue. even with a less sensitive, aft CG.
I also remembered a thread of a F-18 doing the "jump" from a pilot of singapore from some years ago.. impressive pictures and a good save:
http://www.rcuniverse.com/forum/rc-j...l-takeoff.html
This was written before Dr.Honda maiden jet flight.(!)
I also remembered a thread of a F-18 doing the "jump" from a pilot of singapore from some years ago.. impressive pictures and a good save:
http://www.rcuniverse.com/forum/rc-j...l-takeoff.html
This was written before Dr.Honda maiden jet flight.(!)
Flaps, flaps, flaps!!
Hornets "may" need a positive AOA for take off, but they absolutely NEED LOTS of flap for a smooth take off.
I know there are some people (Jetnuno, is one of them I think?) who says a superhornet was his first jet and he doesn't use flaps for take off, but let me assure you, those people are the VAST minority.
Use lots of flaps for take off, you'll be fine!
#64
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Thanks guys - I can honestly say that my 18F did the same vertical takeoff. My CG is 141, and I use 22mm of flaps for departure. I need to wait for John to send parts, but in the meantime, I'm going to add some shim to the nose gear so that we have a positive AOA for takeoff. I'm so glad that God gave me another chance to fly the 18F...I flew the bird on elevator trim...so glad to have a bird to repair: it could have been a lot worse! Thanks guys, and continued success in all you do!
#65
After discussing the cg with Michel (Chile SM dealer), he said that a 130mm is a good place to start. Watch his videos on SM's website and judge for yourself. USE full flaps!
Dan
Dan
#67
Guys, been thru all the same stuff on my SM F18-F. I posted on this previously, aka millsy144. Definately things that will help to alleviate the vertical leaping t/off were-
Lengthening elevator arms to reduce servo slop and resolution. Standard arms are way too short.
Raising nose by lengthening noseleg with packing, and fit heavier springs into shock strut.
With a long enough runway, and as long as nose is sitting high, model will rotate by itself.
Technique of feeding in elevator gradually, until nose starts to lift, then release elevator as soon as model starts to pitch up.
I dont have a massive flap setting for t/off config. Basic flight physics tell you that high flap settings=high drag, not desireable during a takeoff.
If you look at pics and videos of the fullsize counterpart, they actually use a rudder reflex-in mix on takeoff and landing. Possibily, due to the same issues with trailing link landing gear.
Lengthening elevator arms to reduce servo slop and resolution. Standard arms are way too short.
Raising nose by lengthening noseleg with packing, and fit heavier springs into shock strut.
With a long enough runway, and as long as nose is sitting high, model will rotate by itself.
Technique of feeding in elevator gradually, until nose starts to lift, then release elevator as soon as model starts to pitch up.
I dont have a massive flap setting for t/off config. Basic flight physics tell you that high flap settings=high drag, not desireable during a takeoff.
If you look at pics and videos of the fullsize counterpart, they actually use a rudder reflex-in mix on takeoff and landing. Possibily, due to the same issues with trailing link landing gear.
#68
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Yes, this is another solution, having the jet sitting in the ground in a AoA that let it break ground without rotation when the appropiate speed is reached. And you are right too, the rudder reflex-in is for helping pitch up trim at low speeds without using the tailerons.
About basic flight physics, seems that the F-18 defies them... when appropiately powered the F-18 doesn´t care about the extra drag. :-)
https://www.youtube.com/watch?v=2rgWyKLQe00
About basic flight physics, seems that the F-18 defies them... when appropiately powered the F-18 doesn´t care about the extra drag. :-)
https://www.youtube.com/watch?v=2rgWyKLQe00
#73
The China Lake Scheme is my Personal Favorite Orange and White
Here's a link to Airliners.net ... Happy Flying!
http://www.airliners.net/search/phot...471j2297585j10
Here's a link to Airliners.net ... Happy Flying!
http://www.airliners.net/search/phot...471j2297585j10