SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jul 12, 2011, 05:09 PM
Registered User
Joined Jul 2011
44 Posts
@fly inverted

Itīs easy to fly inverted with the corsair. Iīve set spoilerons to 50% and elevator to 12%. The corsair will fly inverted perfectly. Moreover the role is smooth and drawn like a line with this setup.
For cruising and landing I did not use flaps (set to 0%).

Try and see.
Xian01 is offline Find More Posts by Xian01
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 12, 2011, 07:43 PM
Looking4Grass in AZ
Afraidtoregister's Avatar
United States, AZ, Mesa
Joined Feb 2011
1,357 Posts
Quote:
Originally Posted by wab25 View Post
Read the post I quoted. He is giving so much elevator, he is stalling the plane. His solution is to give even more elevator... he is hoping that the prop will provide enough lift to hold the plane up in inverted flight. With this plane, more elevator will make him stall faster and hit harder. He needs airspeed, so that the wing will produce the lift. To get airspeed, he needs less elevator, he needs the nose to come back down, near level.
I mispoke, I meant I was giving a lot of down elevator... because I was inverted. I had it pegged WOT and was giving full down elevator off/on to try to get the nose to tip up to level flight while inverted. The plane wouldn't get the nose up to level, it was losing altitude for a full 10 seconds while I was waiting for the plane to have enough speed to fly level. But I never got any lift, so it smashed into the ground. It looked like it was headed for a hard inverted landing. I assumed that eventually the plane would be able to fly level, but nope, it never was able to. So once it got to about 15 feet off the deck, there was nothing to do but crash. Roll rate is too slow to recovere once that low. I gave full up elevator at the last moment to try to loop back out of it. No luck, prop found the ground.

I added the dime because I didn't feel like repeatedly crashing my Corsair and would try anything to get it to fly. My first 4 or 5 flights required a full rebuild of the plane, I'm $200 into the little thing because I'd throw it up and it would just stall out over and over and crash.

Full up elevator + throttle = loop
No elevator + throttle = suddenly tip up, then stall out
No elevator + no throttle = stall
Full down elevator + throttle = suddenly tip up, then stall out

The only way to get it to do anything but try to tip up and stall out was to cut the throttle and let it crash. I had the elevator trimmed so that by my beginners eye I could see that neutral on the stick was giving a lot of down elevator. That wasn't enough to stop the plane from flying upwards into a stall.

It was frustrating because I'd take the plane out of the box, hand launch it, and it would either do a continuous series of loops until a hard crash or it would tip up for no reason and stall, and then crash because it stalled at shoulder height. Then I'd put it back in the box, rebuild the plane for lots of hard earned money, and have to wait another week for my day off to try to fly it again. And then I'd launch it, and within 5 seconds it'd be in 2 pieces again.

I've never had a plane fly so badly, so the guys at the local club tried it and told me the CG was too far back. I said I'd heard that and that the fix was a dime. They checked and said the CG looked good after the dime addition. I'd be willing to try it with something lighter than a dime... but not without any weight on the nose. I'm sure it will crash right out of my hand.

The physics would be a lot easier to understand without the undercamber wing.
Afraidtoregister is offline Find More Posts by Afraidtoregister
Last edited by Afraidtoregister; Jul 12, 2011 at 08:16 PM.
Reply With Quote
Old Jul 12, 2011, 08:25 PM
Looking4Grass in AZ
Afraidtoregister's Avatar
United States, AZ, Mesa
Joined Feb 2011
1,357 Posts
Quote:
Originally Posted by Xian01 View Post
Itīs easy to fly inverted with the corsair. Iīve set spoilerons to 50% and elevator to 12%. The corsair will fly inverted perfectly. Moreover the role is smooth and drawn like a line with this setup.
For cruising and landing I did not use flaps (set to 0%).

Try and see.
I am unaware as to how to do that. I'll look up spoilerons to see what they are.
Afraidtoregister is offline Find More Posts by Afraidtoregister
Reply With Quote
Old Jul 12, 2011, 08:34 PM
Flyin' low & slow T-28s!
MaladroitFL's Avatar
United States, FL, Vero Beach
Joined Feb 2011
3,324 Posts
It makes me feel good to know that my Dime Adjustment Method DAM (ha ha!) has helped so many.

It was really just a whim, but I was going through the same ordeal as you, Afraidtoregister. It was kind of a last ditch thing before I gave-up on it and shelved it for good.

For those who missed it....
UM F4U Corsair CG Adjustment (7 min 58 sec)
MaladroitFL is offline Find More Posts by MaladroitFL
Reply With Quote
Old Jul 12, 2011, 09:49 PM
Looking4Grass in AZ
Afraidtoregister's Avatar
United States, AZ, Mesa
Joined Feb 2011
1,357 Posts
At one point I picked the plane up and tore it in half. I really wanted the Corsair to be a decent plane. On my second hand launch, I was just barely able to dodge it when it immediately looped when I let go. So mad at the stupid little thing.

But I bet there's some pilot out there that is so amazing that he can correct a plane that does inside loops during full down elevator. /sarcasm

As it stands now, it's just a pretty hard to fly plane that I will not sell (it'd be dishonest) that is completely unrewarding to fly. I'd rather fly the Champ as it is predictable, even if the performance envelope is zero. Sure, it can't do a roll... but the Corsair loses 15 feet of altitude to do one and it takes the entire length of the field to do it. And I can fly the Champ inverted until the wind decides to flip it over as I have no roll control to fight it.
Afraidtoregister is offline Find More Posts by Afraidtoregister
Reply With Quote
Old Jul 12, 2011, 10:02 PM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
12,184 Posts
Quote:
Originally Posted by jseeker101 View Post
OK, glad you brought this up. What in the world is a coordinated turn? How do I know how my tail should track? Why is everyone's eyes better than mine? I can barely make out coming or going with the paint scheme... now, you want me to watch which way my tail track? LOL

At this point, I am happy that A) it turns B) it stays in air

Please school me some knowledge!

Thanks
JS,

In a coordinated turn, an aircraft turns without skidding or side-slipping, and without the nose pointing outward from the turn as the bank is established (adverse yaw). The centrifugal force of the turn & gravity are balanced. If you held drink in your hand, the liquid would stay level with respect the the aircraft, even though you are in a turn. If you had a plum-bob hanging from the ceiling, it would point straight down with respect to the aircraft's horizontal plane. This is the way full-scale planes are nearly always flown. (There are circumstances when you don't fly coordinated turns, but that's for another time.)

A second problem with aileron-only turns is that you can't lift a wing without inducing more drag on the wing, the upward-going wing will have more drag as you use ailerons to establish the bank. This tries to pull the nose in the opposite direction of the turn. It's called adverse yaw. Rudder is used to compensate for this, so that the plane flies through the turn in a coordinated manner, rather than having the nose point outward. Some full-scale & RC planes use differential ailerons. With differential ailerons, you get more up aileron than down. This tends to counteract adverse yaw.

For more info, see below:

Model Aircraft Terminology

http://en.wikipedia.org/wiki/Coordinated_flight

http://en.wikipedia.org/wiki/Adverse_yaw

http://en.wikipedia.org/wiki/Skid_%28aerodynamic%29

http://en.wikipedia.org/wiki/Slip_%28aerodynamic%29

Joel
turboparker is offline Find More Posts by turboparker
RCG Plus Member
Last edited by turboparker; Jul 12, 2011 at 10:31 PM.
Reply With Quote
Old Jul 12, 2011, 10:16 PM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
12,184 Posts
Wab,

Great info on the principles of flight. I have been preaching similar things on the UM threads for a few years, now.

In the case of the F4U, I believe the primary issues when flying inverted are the low flight-speed with the 3-blade prop & the excess nose-weight that some people are using to compensate for a tail-heavy plane. It's pretty tough to fly on the wing with the stock prop - especially if the plane is nose-heavy. With a faster prop & the correct CG, she flies inverted with little elevator input. Many F4Us are quite tail-heavy out of the box. Mine was.
Joel
turboparker is offline Find More Posts by turboparker
RCG Plus Member
Last edited by turboparker; Jul 12, 2011 at 10:27 PM.
Reply With Quote
Old Jul 13, 2011, 12:31 AM
Registered User
thejanitor86's Avatar
United States, FL, St Augustine
Joined Jun 2011
44 Posts
so after putting on a new gws 5043 today i had a rough landing and i heard the whine of what i thought was a stripped gearbox gear. only to find that it wasnt. what i did find however is that the metal pinion on the motor and the gear from the gear box were not interlocking properly. the plane has only been flown 3 times. nothing was bent. so i am wondering if anyone else experienced this. i am just gonna order a new gearbox. but hoping maybe to fix this one as well.
thejanitor86 is offline Find More Posts by thejanitor86
Reply With Quote
Old Jul 13, 2011, 02:07 AM
Looking4Grass in AZ
Afraidtoregister's Avatar
United States, AZ, Mesa
Joined Feb 2011
1,357 Posts
There are a few cracked and melted gearbox reports. Look it over.
Afraidtoregister is offline Find More Posts by Afraidtoregister
Reply With Quote
Old Jul 13, 2011, 02:25 AM
Registered User
thejanitor86's Avatar
United States, FL, St Augustine
Joined Jun 2011
44 Posts
no cracks or melted plastic that i can tell. seems very tight and sturdy still. compared to my p-51 gearbox which is loose and worn but still working perfectly.
thejanitor86 is offline Find More Posts by thejanitor86
Reply With Quote
Old Jul 13, 2011, 06:14 AM
Flyin' low & slow T-28s!
MaladroitFL's Avatar
United States, FL, Vero Beach
Joined Feb 2011
3,324 Posts
I took mine apart yesterday to address the screech, but I couldn't get it to make that ear-wrenching sound.
Took it out for a flight and about 5-minutes in she floated slowly down - screaching like a banshee! It was barely spinning the prop.

The gear looks fine though, so I suspect a cracked gb. The pinion drops down too low after the gb heats up.

Back to cuttin' tape again....
MaladroitFL is offline Find More Posts by MaladroitFL
Reply With Quote
Old Jul 13, 2011, 07:17 AM
Registered User
Joined Sep 2010
4,036 Posts
on mine I had to get the gearbox out before I could see the problem. The gearbox was deformed like it had been put in an oven and the motor would not fit back into the front of the box that holds the front of the motor. Went through the same as above, screech, loose power, check it out, fly it later and it would fly for a minute, then screech, loose power. A new gearbox and cutting the front of the decal and some foam out so some air could get in was the cure. I believe the gears on mine were actually rubbing the foam a bit out of the box. Mine did have the totally unpredictable flight characteristics that many mention. My best solution so far has been using my 280ma mosquito batteries with the end of the battery right up against the cowl venting fins that run around the nose. I use a double piece of velcro to hold it in with a small rubber band around the nose and battery right behind the cowl. I have also found mine to need lots of control movement, especially ailerons. I have the control rods moved in to the next to closest hole. And I use a stock T28 prop per the suggestion in the manual.
bobly is online now Find More Posts by bobly
Reply With Quote
Old Jul 13, 2011, 10:24 AM
Registered User
Joined Jun 2011
135 Posts
I bought a UM Corsair because I flew a friends UM Mustang and T-28 but love the way a Corsair looks. I had a big "gasser" Top Flight Corsair that I loved to fly because it just looked so good and flew great. This little one is not that plane . I too had a tail-heavy plane right out of the box and the first flight was very touchy. Did the "dime fix" to correct the CG but I just believe the plane is just underpowered. I have flow R/C planes for over 20+ years and have flow many under powered and over powered planes. I believe this plane out of the box is under powered even with a good motor. It is just too heavy for the factory motor/prop. Mine will loop and roll but much depends on what battery you use and if you have a "good" motor or "bad". I also fly a UM Beast and Sbach. Do not fly one of these and then fly the Corsair. The Beast and Sbach are not under powered. I now still fly my Corsair if there is no wind and I just want to relax, fly around the park, and admire how good it looks on fly-bys.
I did also have a problem with gearbox "melt down" and so I replaced it and opened up the front sticker so the gearbox has air flowing over it and have not have any more problems with the new gearbox screech/fail issue.
nickimde is offline Find More Posts by nickimde
Last edited by nickimde; Jul 13, 2011 at 10:33 AM. Reason: add pic
Reply With Quote
Old Jul 13, 2011, 11:12 AM
Registered User
Sausalito Marin Cty, California, United States
Joined Aug 2004
892 Posts
Quote:
Originally Posted by turboparker View Post
Wab,

Great info on the principles of flight. I have been preaching similar things on the UM threads for a few years, now.

In the case of the F4U, I believe the primary issues when flying inverted are the low flight-speed with the 3-blade prop & the excess nose-weight that some people are using to compensate for a tail-heavy plane. It's pretty tough to fly on the wing with the stock prop - especially if the plane is nose-heavy. With a faster prop & the correct CG, she flies inverted with little elevator input. Many F4Us are quite tail-heavy out of the box. Mine was.
Joel
Your statement in bold confuses me a bit. Being that the complaint is that the stock prop does not have enough thrust, wouldn't it be even harder to fly on the prop instead?
wab25 is offline Find More Posts by wab25
Reply With Quote
Old Jul 13, 2011, 02:19 PM
Registered User
United States, DC, Washington
Joined Feb 2008
313 Posts
After reading everyone's comments, I went out and apply the throttle for height and ele for speed principle. I am having trouble adapting the ele for speed part but the throttle for height is coming along.

I still don't understand coordinated turn as far as what to do. The principle of why it is needed has been explained. But I can't find the how. Do I do rudder in same direction? opposite direction as aileron? How much and when?...etc. I do have differential @ 2:1 up:down with this one if that matters.

Through the process, I discover that when banking left, I don't need much if any up ele to keep the nose up. When banking right, the nose wants to dive. How do I correct that? Or is it even possible to correct - meaning, I just have to know left is different from right so my finger does different things with the stick? I do recall having to trim out rudder but don't recall which direction. I know when banked, rudder becomes ele and having it trimmed I am sure probably caused one side to be "up" and the other "down" almost like doing a KE where you have to use rudder to stay level.

I must admit, I am one of those who is guilty of NOT checking CG and simple rely on the forum's info. In my defense, I did fly with 160 first and was unable to trim it proper. After the 240 or dime + 160, I was able to trim it out. So, with all this recent CG talk, I did measure mine last night. Mine is also tail heavy stock and with 240 or dime + 160 it is "good enough". The 2 methods for me is probably within 1 click trim of each other and when flying, I don't notice the difference. It is all base on what batt I have charged at the time dictate the config.

Any thoughts on any thing above appreciated.
jseeker101 is offline Find More Posts by jseeker101
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Blade MCP X - owner's thread rchelijc Micro Helis 13062 Sep 19, 2014 11:12 AM
Discussion Parkzone vs.BlitzRCWorks F4U Corsair (which one) wjohnson1186 Beginner Training Area (Aircraft-Electric) 21 Nov 05, 2012 02:55 PM
Discussion Parkzone f4u corsair VS Airfield f4u corsair Hoopsta17_99 Electric Warbirds 54 Mar 16, 2012 09:11 PM
Discussion Difference between Parkzone's different Ultra Micro planes? bunger Scratchbuilt Indoor and Micro Models 21 Jul 10, 2011 04:32 PM
New Product New Ultra Micro F4U Corsair BNF by ParkZone P-51C Micro Ready-to-Fly 3 Feb 23, 2011 11:27 AM