Suggestions for .25/.30 Build Kit
08-31-2007, 07:14 PM
#27
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RE: Suggestions for .25/.30 Build Kit
ORIGINAL: WMB
I'm currently flying the Kobra. I have 50 flights on it now. Mine has an OS32F, it's quick and agile but not what I would call overly fast. The taildragger mod would be great. It's fun to put into a dive then pull into upline and let it snaproll, talk about violent and it's held together. Slows way down for a nose high landing that looks so cool. Will snap with excessive up elevator, but release stick and it's flying again. Fun plane, I want to build the 40 size version Kougar.
I just picked up an FX25, it will be doing duty on a Shrike 10. Flies great with the 15, but is really lacking speed.
Have fun, MikeB
I'm currently flying the Kobra. I have 50 flights on it now. Mine has an OS32F, it's quick and agile but not what I would call overly fast. The taildragger mod would be great. It's fun to put into a dive then pull into upline and let it snaproll, talk about violent and it's held together. Slows way down for a nose high landing that looks so cool. Will snap with excessive up elevator, but release stick and it's flying again. Fun plane, I want to build the 40 size version Kougar.
I just picked up an FX25, it will be doing duty on a Shrike 10. Flies great with the 15, but is really lacking speed.
Have fun, MikeB
I saw a Kobra at the hobby shop today and was very tempted to get it for my Magnum 36. That looks like a fun build, and even better flying.
Does it have much coupling in knife-edge? I have an Ultra Sport 40 that is similar if only slightly larger, but it has a ton of knife-edge coupling.
Brett
08-31-2007, 09:21 PM
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RE: Suggestions for .25/.30 Build Kit
"Does it have much coupling in knife-edge? I have an Ultra Sport 40 that is similar if only slightly larger, but it has a ton of knife-edge coupling. "
If I lay it all the way on it's side, it takes a lot of rudder and speed to hold elevation. It wants to roll out to upright and pulls to the canopy. I don't lay it quite on it's side and it does much better and looks good. It seems to knife edge better with the right wing down, doesn't pull to canopy as much as when left side is down.
Another great mod (I think
) would be to bring the fuse rear together rather than boxed. Split the elevator and run the rudder to the bottom of the fuse. I haven't done this, but will in the future with a Kougar.
I am having a lot of fun with it. More power would be better if weight didn't go up. When the temps are on the cool side, I get unlimited verticle with good speed using the MA 9x7. The APC9x6 gives similar performance, but I think it's a hair slower.
One thing I have noticed is the twitchiness of the ailerons at low landing speeds. Kind of spooky to barely give input and get the wing rocking close to the ground. I dialed in about -35% expo and that smoothed it out. I do have more throw than suggested, so I created my own problem.
Those nose high landings are the best!
Go fot it, I don't think you will regret it unless you're looking for 3-D type flying.
If I lay it all the way on it's side, it takes a lot of rudder and speed to hold elevation. It wants to roll out to upright and pulls to the canopy. I don't lay it quite on it's side and it does much better and looks good. It seems to knife edge better with the right wing down, doesn't pull to canopy as much as when left side is down.
Another great mod (I think
) would be to bring the fuse rear together rather than boxed. Split the elevator and run the rudder to the bottom of the fuse. I haven't done this, but will in the future with a Kougar. I am having a lot of fun with it. More power would be better if weight didn't go up. When the temps are on the cool side, I get unlimited verticle with good speed using the MA 9x7. The APC9x6 gives similar performance, but I think it's a hair slower.
One thing I have noticed is the twitchiness of the ailerons at low landing speeds. Kind of spooky to barely give input and get the wing rocking close to the ground. I dialed in about -35% expo and that smoothed it out. I do have more throw than suggested, so I created my own problem.
Those nose high landings are the best!
Go fot it, I don't think you will regret it unless you're looking for 3-D type flying.
09-02-2007, 06:16 AM
#30
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RE: Suggestions for .25/.30 Build Kit
I greatly appreciate all of the posts, emails, IMS, phone calls, letters, skywriting, and telepathy everyone has volunteered! I'm enjoying learning about new planes, seeing the ones that all of you like, and trying to decide what to choose. Here's where I'm leaning based on your input:
[ul][*] 4-40 Bipe, scaled to fit the OS .30 Surpass. (I'll have to use a different pilot figure than the one listed in the plans!) This one appeals to me for several reasons. It's not a kit so it'll be a builder's build. It's a bipe, has great flying characteristics, and will be a great fit aesthetically for the 4-stroke. Additionally, since my trunk space is limited I like that the wing design will allow me to easily remove both wings![*] Sig Kobra, built as a tail-dragger with retracts and flaps. Aside from getting great press from many of you about it's flying characteristics, building from a kit will require slightly less mental energy, and it'll be fun taking this kit off the beaten path with design changes and a non-Jet finish. Maybe...
[/ul]
So now I gotta let this settle and simmer and see if these "feel right", or maybe just figure out which one to build first!
EG
[ul][*] 4-40 Bipe, scaled to fit the OS .30 Surpass. (I'll have to use a different pilot figure than the one listed in the plans!) This one appeals to me for several reasons. It's not a kit so it'll be a builder's build. It's a bipe, has great flying characteristics, and will be a great fit aesthetically for the 4-stroke. Additionally, since my trunk space is limited I like that the wing design will allow me to easily remove both wings![*] Sig Kobra, built as a tail-dragger with retracts and flaps. Aside from getting great press from many of you about it's flying characteristics, building from a kit will require slightly less mental energy, and it'll be fun taking this kit off the beaten path with design changes and a non-Jet finish. Maybe...
[/ul]
So now I gotta let this settle and simmer and see if these "feel right", or maybe just figure out which one to build first!
EG
09-02-2007, 07:15 AM
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RE: Suggestions for .25/.30 Build Kit
Not to confuse you, but if you're interested in scratch building, I remembered a plane I built a while ago. Go to the [link=http://209.196.57.92/ME2/dirmod.asp?sid=521FEB3C003A47F1B2FD524B47FF0DF7&nm=Test&type=EcomBB&mod=E%2DCommerce%3A%3AProduct+Catalog&mid=D30FB4BBE3764A5694C4972616B7262A&tier=2&cat=Plans&ntier1=Plans]Plans page for Model Airplane News and R/C Boat Modeler[/link] and search for plan number fsp06801. It's called the Sidewinder. It's a .25 size pattern plane I built in the mid-80s. Mine had an OS .25F ABC. It's got a foam wing and anhedral stab. Looked very cool, flew great, and was an easy build. It could easily be built as a taildragger and from memory, there was plenty of room in the wings for retracts. I still have the plans and may build another someday.
09-02-2007, 12:34 PM
#32
RE: Suggestions for .25/.30 Build Kit
WMB, don't confuse KE control coupling [even though the term sounds cool] with flying around with up trim in the elevator all the time due to having a nose heavy plane. Try shifting your CG back some and see if the KE coupling problem improves.
My thoughts about most .25 powered projects that I've ever seen......they fly like under powered .40 sized sport models if the all up weight isn't limited to 3 pounds max. If a .25 sized project is approached with a ".15 builders'" mentality instead of a ".40 builders'" mentality, the outcome should be a plane with outstanding performance.
The Cobras that I've seen were OK with .36s and .32s but nothing too special.
I think a HoB .25 P-51 looks like a better plane.
My thoughts about most .25 powered projects that I've ever seen......they fly like under powered .40 sized sport models if the all up weight isn't limited to 3 pounds max. If a .25 sized project is approached with a ".15 builders'" mentality instead of a ".40 builders'" mentality, the outcome should be a plane with outstanding performance.
The Cobras that I've seen were OK with .36s and .32s but nothing too special.
I think a HoB .25 P-51 looks like a better plane.
09-02-2007, 04:01 PM
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RE: Suggestions for .25/.30 Build Kit
"WMB, don't confuse KE control coupling [even though the term sounds cool] with flying around with up trim in the elevator all the time due to having a nose heavy plane. Try shifting your CG back some and see if the KE coupling problem improves."
I don't think it is nose heavy due to two things. Inverted doesn't take much down and the landings are so smooth and nose high. However, I am a little curious now so I will move CG back a bit. I flew my 4*40 for a couple years and was amazed at the difference in flight with the cg moved back. I knew I went too far when it would flare forever than stall and drop when landing.
I understand how the nose heavy can cause a pull to canopy in KE. What is making it roll to upright? I can't help but think it is forces above the thrust line by the rudder that causes the roll to upright when in KE.
The HoB P-51 does look like a fun one.
I don't think it is nose heavy due to two things. Inverted doesn't take much down and the landings are so smooth and nose high. However, I am a little curious now so I will move CG back a bit. I flew my 4*40 for a couple years and was amazed at the difference in flight with the cg moved back. I knew I went too far when it would flare forever than stall and drop when landing.
I understand how the nose heavy can cause a pull to canopy in KE. What is making it roll to upright? I can't help but think it is forces above the thrust line by the rudder that causes the roll to upright when in KE.
The HoB P-51 does look like a fun one.
09-02-2007, 04:38 PM
#34
RE: Suggestions for .25/.30 Build Kit
WMB, since the draggiest part of your plane is towards the canopy, it makes sense that the plane will pull to that side in KE flight. But there might be an aerodynamic fix, without resorting to gluing the canopy onto the belly.
The other thing to investigate is the aileron bias at neutral. I hate to suggest programming them to a flap dial, because of the disasterous effect it can have in flight if you over control the knob, but that is another avenue of approach.
Raising the ailerons slightly [lees than a degree] might do some good?
About the rolling, flying KE is like balancing a balloon on a stick. The heavier planes are a real challenge to KE with a fuselage that is relatively shallow. You have to start out with a very straight plane that hasn't been tweaked with your trim levers to fly straight. I would put the plane up on a table, get a framing square, some yard sticks, etc. and check that the plane is absolutely twist free and square.
Those SFG plates would be an interesting experiment to tape onto the wing?
The other thing to investigate is the aileron bias at neutral. I hate to suggest programming them to a flap dial, because of the disasterous effect it can have in flight if you over control the knob, but that is another avenue of approach.
Raising the ailerons slightly [lees than a degree] might do some good?
About the rolling, flying KE is like balancing a balloon on a stick. The heavier planes are a real challenge to KE with a fuselage that is relatively shallow. You have to start out with a very straight plane that hasn't been tweaked with your trim levers to fly straight. I would put the plane up on a table, get a framing square, some yard sticks, etc. and check that the plane is absolutely twist free and square.
Those SFG plates would be an interesting experiment to tape onto the wing?
