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Old May 06, 2011, 11:03 PM
Flyin' low & slow T-28s!
MaladroitFL's Avatar
United States, FL, Vero Beach
Joined Feb 2011
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Originally Posted by turboparker View Post
Picked my B&F up at the LHS yesterday, and flew it in the parking lot. Problem was - shortly after takeoff, the wind picked up to 15+ MPH. That was one of the most hairy flights I can remember in my 27+ years of flying RC. The F4U does not like the wind! At least not as compared to the Sukhoi XP.

I checked everything over & decided that it needed more elevator & rudder, so I moved the elevator to the third hole from the top, and I moved the rudder to the second hole from the inside. I then centered the surfaces mechanically. Popped in a freshly-charged Hyp 160 cell & headed to the parking lot. She sat on the tarmac just fine, despite the wind. I rolled into the throttle & fed in right-rudder. The P-factor is significant on this one. If you're not good with the rudder, this plane will teach you to be. She was airborne within 10 feet.

At about 20 feet AGL, things went awry. The wind had picked up significantly at ground level. Up there, the F4U struggled. The wind made her balloon straight up & back over my head. I fought the sticks & got her under control. She didn't have enough speed to make headway, and I fought to bring her back to the parking lot. I found myself really wishing I had increased the aileron throws. In a dive @ WOT, she was just barely moving forward, and then backwards she went. She was heading tail-first towards a garden shop's tent that was set up in the adjacent lot. In a last-ditch effort to save her, I dove for the windward side of the tables & attempted a hover-landing. I lost sight of the plane during the last 10 feet of descent, but I managed to get her down without a scratch. Needless to say, I didn't fly her again.

As I was driving home from the LHS, I noticed that the flags were motionless. Since I had everything I needed with me, I went directly to the club's asphalt runway. I maxed the rudder throw & moved the ailerons to the second hole from the top of the horns.

I flew a bunch of Hyp 160s in the calm, and had a chance to really wring her out. I assessed the CG placement, and ended up with the Hyp 160 at the front of the slot. Even so, she acted like she may be just a slight bit tail-heavy for a warbird. See below:

Flight conditions:
920' AMSL
73 F, calm

Takeoff & climbout

The P-factor is quite noticeable on this plane, so takeoffs require a fair amount of rudder. Rolling into the throttle gives best results. Those who use some finesse on the throttle & know how to use the rudder will be rewarded with great-looking scale takeoffs. Climbout is leisurely as compared to the UM P-51.

General flight

The F4U tracks well. In the calm, low passes look great, and it's easy to fly circuits @ WOT just inches off the deck. Coordinated rudder rewards the pilot with scale-looking turns. She's rock-solid - even at slower speeds, but she'll drop a wing suddenly when slowed to a stall. Recovery is quick, however.

Aerobatics

Even with the Hyp 160 cells, my F4U can just barely loop from level flight. Speed bleeds of quickly during climbs. Even short vertical climbs are a challenge.

With the increased aileron throw, rolls are about right for a warbird. Maintaining altitude throughout the roll requires quite a bit of top-rudder & a fair amount of down-elevator, however.

Inverted flight is possible, but she doesn't really enjoy it. Later into the flight, it is difficult to climb when inverted.

Landing

Keep some power on, and she's a pussycat on approach. Use throttle to manage sink-rate, and use elevator to manage speed. When she's in ground-effect, relax the elevator a bit & let her down on the mains as you cut the power. She'll do a great-looking two-wheel landing, and the tail will still be flying during the rollout. If you'd rather do a 'carrier landing' - just bring her down as above, but flare for a 3-point landing & plant her solidly on the deck.

Conclusion

The 4FU is a relaxing plane to fly. She's rock-solid on the sticks, which makes it fun to do really low passes @ WOT. Shooting touch & goes is a blast, and she looks great in the air and on the runway. However, she is sorely lacking the speed & climb performance one expects from one the top-performing warbirds of the era. She should be capable of performing large, round loops. She should be able to execute a decent Immelmann. She should be able to execute a zoom-climb. However, the above maneuvers are not possible with my particular aircraft. In general, she seems to be flying too slow - even at WOT. The UM P-51 is a more capable performer. I suspect that the 3-blade prop is the culprit, and will be trying a 5043.

Joel
Excellent review!
Thanks, Joel.
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Old May 06, 2011, 11:32 PM
Registered User
Ridgecrest Calif
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Originally Posted by turboparker View Post
don't discharge them beyond 80% as measured in mAh required to recharge. (Requires a charger that displays charge data). Discharging beyond 80% is the quickest way to kill your LiPos - regardless of brand.
Can't argue with the reasonableness of maintaining a minimum 20% charge, but I get the feeling it's just a number picked out of the sky. I like to keep my post-flight voltages above 3.7V, but I have no data to say 3.6 or 3.5 wouldn't produce comparable battery lifetimes. Overuse is bad, no question. But do you really have any hard data to back up an actual number? Or would you admit this just seems like a reasonable rule of thumb? (I'm actually hoping you have the data -- I'd like to have a look)
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Old May 07, 2011, 12:25 AM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
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Originally Posted by WAM74 View Post
Can't argue with the reasonableness of maintaining a minimum 20% charge, but I get the feeling it's just a number picked out of the sky. I like to keep my post-flight voltages above 3.7V, but I have no data to say 3.6 or 3.5 wouldn't produce comparable battery lifetimes. Overuse is bad, no question. But do you really have any hard data to back up an actual number? Or would you admit this just seems like a reasonable rule of thumb? (I'm actually hoping you have the data -- I'd like to have a look)
Wam,

I did not pick the number out of the sky. It is the number quoted by all LiPo manufacturers, and it is derived from the chemistry. Doesn't matter which brand - it's the same for all LiPo cells. This is no different than any other secondary cell. They all have a maximum depth-of-discharge rating that is dictated by the chemistry. If you regularly discharge LiPos beyond 80%, the cells will suffer irreversible damage that will dramatically reduce their lifespan & performance. In fact, over-discharge is the #1 cause of early LiPo failure.

See Hyperion's LiPo care page:

http://media.hyperion.hk/dn/g3lipo/

Joel
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Old May 07, 2011, 12:59 AM
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Ridgecrest Calif
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Originally Posted by turboparker View Post
If you regularly discharge LiPos beyond 80%, the cells will suffer irreversible damage
Close enough. It actually says 10% capacity is the minimum acceptable, but 20% is the recommended. Since I go by post-flight voltage, I'll have to see if I can get a correlation there. I don't use my fancy charger for my 1S bats.

Thanx for the link.
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Old May 07, 2011, 01:00 AM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
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Quote:
Originally Posted by MaladroitFL View Post
Excellent review!
Thanks, Joel.
Mal,

You're welcome! And thanks for the kind words! I'm checking the hour-by-hour wind forecast for tomorrow morning & it looks like it'll be great for UM flying in the early morning. I'm planning to head to the field early with my F4U, Mossie, Beast, XP - and my 48" Precision Aerobatics Extra 260 unlimited ship. My F4U seems to be just a tad tail-heavy. Not by much, but I notice a slight ballooning tendency just as I cut the power to land. Might not actually be a CG issue, though. CG, incidence & thrust-line problems can have similar symptoms.

Since I had the Hyp 160 fully-forward, I'm going to try the heavier Hyp 180 'flat-pack' cell. I'll know right away if moving the CG forward solves the problem. I'm thinking about trying a 5043 while I'm at it. Ground clearance seems to be adequate - I might as well give it a go.

Joel
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Old May 07, 2011, 01:22 AM
Gopher huntin' stick jockey
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East Bethel, MN USA
Joined Jul 2009
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Originally Posted by WAM74 View Post
Close enough. It actually says 10% capacity is the minimum acceptable, but 20% is the recommended. Since I go by post-flight voltage, I'll have to see if I can get a correlation there. I don't use my fancy charger for my 1S bats.

Thanx for the link.
Wam,

Why not charge them on your "fancy" charger to establish a baseline? Once you establish a baseline for a typical aggressive flight, just set your flight-timer for 30-60 sec less than the 80% point & you should be fine. You could also discharge one of them to the 80% point with your charger, and then record the resting voltage. After that, you could just go by the resting voltage.

If you're flying premium LiPos such as Hyperion, Intellect, or TP - and you want to get the claimed '300+cycles with no loss in performance' - never discharge them below 80%.

Joel
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Old May 07, 2011, 07:51 AM
CRASH, FIX, REPEAT
helibard's Avatar
United States, KY, Bardstown
Joined Apr 2010
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Thanks for the review Joel, I've got my fingers crossed for fathers day!
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Old May 07, 2011, 09:38 AM
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Ridgecrest Calif
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Quote:
Originally Posted by turboparker View Post
Wam,

Why not charge them on your "fancy" charger to establish a baseline? Once you establish a baseline for a typical aggressive flight, just set your flight-timer for 30-60 sec less than the 80% point & you should be fine. You could also discharge one of them to the 80% point with your charger, and then record the resting voltage. After that, you could just go by the resting voltage.

If you're flying premium LiPos such as Hyperion, Intellect, or TP - and you want to get the claimed '300+cycles with no loss in performance' - never discharge them below 80%.

Joel

Well two reasons. I don't have a micro plug for the supercharger. I'm sure I could come up with something. And I don't rely on my timer because I'm terrible at starting/stopping it. I fly four to six short flights on a battery -- that's just what I like. And my DX6i timer doesn't have a throttle trigger. That would be nice. I think it can be hacked in, but I'm not that familiar. But I've never yet found my batteries to be below 3.7V so I guess it's working out.

Do you happen to have any voltages from micro batteries drained to 20%?
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Old May 07, 2011, 10:27 AM
Way to many airplanes!
Canada, QC
Joined Oct 2009
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Originally Posted by WAM74 View Post
Do you happen to have any voltages from micro batteries drained to 20%?
Voltage is not a good indication for a lipo capacity. Depend too much on the chemistry used in the battery, the internal resistance, and other factors. It can be safely used if you know how much current you put back in your battery before....

Ex.: You have a 160mah battery. Maximum discharge would be 80%, so when you charge it, you should not have to put more than 128mah in it.

Now let's take two different manufacturer, with two batteries for each of them, one being new and one being old. You discharge them all by removing exactly 128mah in them.

You may end up with:
Manufacturer A
New: 3.8volts
Old: 3.65volts
Manufacturer B
New 3.6volts
Old 3.4volts

So the trick is really to make sure you check the current you put into a battery while checking what voltage your battery is sitting at room temperature.

Let say you use a battery and happen to put back 120mah in it and noticed that it was sitting at 3.6volts before the charge, then you can trust the fact that this battery can be relatively discharged to 3.6volts and up.
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Old May 07, 2011, 06:01 PM
Team OFG (Old Fat Guys)
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United States, KY, Leitchfield
Joined Jul 2008
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My Corsair

I picked mine up in Louisville today at Scale Reproductions. It looks great! The tri color paint scheme is too cool and the clear canopy is awsome. I am hoping for good weather here in Kentucky tomorrow and maybe I can get a maiden flight in.
I noticed someone posted a rates post, so I will check that out before I take her up the first time. I think most people are really bragging on the plane, so I have high expectations of the first flight.
Pics tomorrow......with luck.
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Old May 07, 2011, 06:17 PM
Gopher huntin' stick jockey
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East Bethel, MN USA
Joined Jul 2009
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Flight report - F4U w/GWS 5043 prop + Hyp 180 'M' cell

Just got back from an entire day of flying at the club field!

I brought my F4U, Mossie, UMX Beast, and Precision Aerobatics Extra 260. I also brought my keychain cam & shot a bunch of on-board video from the Extra. The wx was perfect - 70 F, with hardly a breath of wind.

I installed the 5043, and taped the Hyp 180 to the belly with a bit of masking tape. For proper CG, I ended up with the end of the cell in line with the front of the battery slot - which confirms that mine was just a tad tail-heavy with a stock-weight cell at the front of the tray. Now that I've found the proper CG, I will carve out just enough foam to flush-mount the Hyp cell, as I did with the Champ & Sukhoi.

I taxied her out & checked the sticks. I lined her up on the asphalt, and rolled into the throttle. She was airborne within 10 feet, and was moving out quite nicely. I hauled back on the stick, and she gobbled up the sky. Rolled her inverted at the top of the climb, and dove for the deck @ WOT for a strafing run. She came downstairs like a bat-outta-hell, I leveled out @ 4 feet off the deck and let her rip. Back on the stick again, and up she went. I slammed in full left aileron, rolled her straight up for ~100 feet. I came out of the climb inverted, and performed a split-S. I came around, lined her up and brought her in for a two-wheel landing. Back on the throttle, and up she went.

I flew around 20 flights - all with the 5043 & Hyp 180s. She now performs as an air-superiority fighter should perform. Big round loops, Immelmanns, zoom-climbs, wingovers, stall-turns, hammerheads, fast & slow rolls, high-speed strafing runs - she performs them all with aplomb.

I got to the field at ~9 AM, and flew until it started to sprinkle a bit at ~5 PM. As the day progressed, I alternated between aircraft. By noon, there were a fair number of members at the field. The wind came up a bit - around 4-5 MPH gusting to 12. Thanks to the 5043 & Hyp 180, the F4U handled it with ease. I received lots of comments on how well it flew.

I absolutely love shooting touch & goes, doing nice 'n long scale take-offs, and doing 2-wheel landings with long rollouts. I also love to take her upstairs, roll over into a power-dive, let her scream downhill @ WOT, then ease the stick back for a scale pullout, and end up @ maybe 5 feet off the deck for a high-speed pass across the field. The 5043/Hyp 180 combo appears to at least double her speed @ WOT. This results in handling that is so rock-solid, it inspires the pilot to fly her right down on the deck @ WOT - much like a Reno racer.

Conclusion:


The 5043 prop & Hyp 180 literally transform the plane. With the increased speed and thrust, she now flies like a dream. I will not be going back to the three-blade!

Joel
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Old May 07, 2011, 07:06 PM
CRASH, FIX, REPEAT
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United States, KY, Bardstown
Joined Apr 2010
926 Posts
Quote:
Originally Posted by BigD1961 View Post
I picked mine up in Louisville today at Scale Reproductions. It looks great! The tri color paint scheme is too cool and the clear canopy is awsome. I am hoping for good weather here in Kentucky tomorrow and maybe I can get a maiden flight in.
I noticed someone posted a rates post, so I will check that out before I take her up the first time. I think most people are really bragging on the plane, so I have high expectations of the first flight.
Pics tomorrow......with luck.
Hey buddy, I get alot of my stuff at Scale Reproductions also. Alot of my heli stuff too. I live in Bardstown Ky. and thats the closest one near me. Love that place. Let me know how that new Corsair flies. Cant wait to get one!
Jim
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Old May 07, 2011, 08:04 PM
Flyin' low & slow T-28s!
MaladroitFL's Avatar
United States, FL, Vero Beach
Joined Feb 2011
3,324 Posts
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Originally Posted by turboparker View Post
... - she performs them all with aplomb.

Joel
You wrote that whole piece just so you could use the word, "aplomb." Which ruined it for me because I was going to use aplomb sometime this week.

Darn you , Joel!
Nice review, btw.
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Old May 07, 2011, 10:45 PM
Gopher huntin' stick jockey
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East Bethel, MN USA
Joined Jul 2009
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Quote:
Originally Posted by MaladroitFL View Post
You wrote that whole piece just so you could use the word, "aplomb." Which ruined it for me because I was going to use aplomb sometime this week.

Darn you , Joel!
Nice review, btw.
LOL!!

Thanks!

If you're interested, here are a few videos I shot from my Precision Aerobatics Extra 260 today. I apologize for the nasty prop artifacts. I'm getting a better cam. I'm just using this one to experiment with flight technique & camera mounting. I think the last one turned out the best. I reduced the rates & moved the CG forward a bit to improve smoothness a bit. The clouds provide some perspective during the vertical maneuvers:

http://www.rcgroups.com/forums/showp...postcount=4796

Joel
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Old May 08, 2011, 05:35 AM
Flyin' low & slow T-28s!
MaladroitFL's Avatar
United States, FL, Vero Beach
Joined Feb 2011
3,324 Posts
Quote:
Originally Posted by turboparker;18174354[B
Conclusion:[/B]

The 5043 prop & Hyp 180 literally transform the plane. With the increased speed and thrust, she now flies like a dream. I will not be going back to the three-blade!

Joel
Flying last night just as the sun was dropping behind the tree line in the west, I was actually walking around the large field where a few of us fly with the Corsair in the air. I was helping a friend find his Champ which had been hijacked by an upper wind and had landed on the far side of a fairly busy entry road to our subdivision. (We fly in an un-developed section where the road and lights/sewage are in, but no homes yet.)
So instead of just walking the 400 yds with him, I flew the Corsair in circles around us as we walked.
All the way out - and all the way back. The Corsair buzzed us as we progressed to the Champ, then headed all the way back. During the entire 10-minute search and rescue, I never once saw the F4U get into any trouble or "close calls."
It's just a great flying little warbird!
I think I'll stick with the 3-blade, because I have all the performance I need. Things change as we progress as RC pilots, but for now, the Corsair is pretty much able to reach the outer edges of my ability.

I'm supposed to meet a few guys over there to fly this morning @ 8AM, but I'm up early (to water my veggie garden) and I just might slip out and get a few 7AM flights in before the others arrive.
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