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hangar 9 corsair needed fixes before 1st fight

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Old 01-23-2010, 02:21 AM
  #1
villa22
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Default hangar 9 corsair needed fixes before 1st fight

im taking my time and building my hangar 9 corsair reading as much as i can before i start the motor.
my question is that i heard about wing failure firewall failure and many peoples opion on the matters
but most of these post are very old (years) now 2010 im building mine ill be flying a new zenoaha g20 and i do not want to watch my wing fail as some have. has this maufacture defect been fixed i cant find as answer. what are people upgrading on the air frame before 1st flight thanks
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Old 01-23-2010, 12:22 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

I just built mine about a month ago and heard the same issues. But usually with all my 60 size and larger ARFs I do a little extra stiffening. So here's what I did:

- Inside the wing area around the retract bay and the wheel well I added additional 2 layers of 30 minute epoxy. I found this area was very thin on glue and sheeting and I could crush it with just light pressure.

- In the wing area where the wing sheeting is bent (to form the upswept wing) I added another layer of thick blase and then some more epoxy. The sheeting in this area on my plane was splitting (which is probably normal for this plane due to the large upsweep).

- On the retract rails, more epxoy on the sides and around the ribs where they are mounted.

- Then more expoxy on all the inner walls of the fuse, inside firewall, and then again on the firewall itself. I didn't add another plate on the firewall because it appeared pretty good (and so far so good).

- Basically, anywhere there was exposed balsa sheeting I added a layer of 30 minute epoxy.

As I mentioned, this is stanard practice on all my larger planes and it seems to do the job. I have a full fleet of the H9 60 size warbirds (2 P51s, P-47, Corsair, Hellcat) and they all received the treatment. And they are all flying fine. On my corsair I'm using just a OS 75 AX which pulls it around the sky pretty good. Scale flight is at about 1/3 throttle. One of the P-51s is my speed plane so I have a OS 95 AX (2 stroke) in it so it hauls pretty good. Scale flight on this plane is just above idle (yes, it will do loops and slow rolls at about 1/4 throttle). At full throttle it's a quick hop from one end of the field to the other (and our field is pretty huge). It's off the pavment on takeoff at idle (about 10-12 feet) - really. Waaaay to fast but I say all that to say with the treatment it's holding up well. I fly it regularly (3 flights on it this past Thursday).

Hope this helps.
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Old 01-23-2010, 03:41 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

It is difficult for me to take you seriously when you indicate concerns for firewall failure and/ or a wing failure, then you state that you are going to install a Zenoah G-20 on it.
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Old 01-23-2010, 05:43 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

AMEN to that
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Old 01-23-2010, 07:03 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

my desition to fly the zenoah was based on the marites of the engine and its performance in the h9 corsair from others peoples testimonials and quite frankly im not sure witch one i like more the engine or the plane. i found out about the firewall issue after the purchuse of the engine. but i can see that issue seems to have been addressed by the factory and i can stiffen it up to be safe. but this wing failure at the landing gear bay does not have a clear answer i perfer not to remove the factory skin but will if that is what is needed.
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Old 01-23-2010, 07:18 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

If you put a .91 4-stroke on it you probably wont have to do anything extra. I have the H9 P-40 and F6F, both with a .91 4-stroke. The landing gear on both hold up ok as long as you keep the plane light.
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Old 01-23-2010, 10:21 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

No need to remove skin or anything. Just add some extra epoxy to the exposed areas that you can get at. H9 addressed the issues with this bird a long time ago. The stuff I do is just a for a little extra safety. Also, I agree. The G20 is waaaay more motor than this plane needs and it also adds alot of extra weight. The thing about the H9 warbirds is that are built to balance nicely with 2/4 stroke nitro motors like 61 strokes or 91/100 4 strokes. With mine I actually added some tail weight.

BTW, 2 more flights on the P51 this afternoon and everything's holding up just fine.
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Old 01-24-2010, 11:51 AM
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Default RE: hangar 9 corsair needed fixes before 1st fight

Quote:
ORIGINAL: villa22

my desition to fly the zenoah was based on the marites of the engine and its performance in the h9 corsair from others peoples testimonials and quite frankly im not sure witch one i like more the engine or the plane. i found out about the firewall issue after the purchuse of the engine. but i can see that issue seems to have been addressed by the factory and i can stiffen it up to be safe. but this wing failure at the landing gear bay does not have a clear answer i perfer not to remove the factory skin but will if that is what is needed.
The firewall issue has been addressed by H9 for the recommended engines. I always use fiberglass and thinned epoxy to reinforce ARF areas of high stress and vibration. The firewall needs that in the Corsair. I have CJ retracts and a bomb drop on mine so it weighs a little more than recommended. I have two wings. The first one started to flex after about 20 flights. I then purchased a second wing and reinforced the wing with light fiberglass and thinned epoxy. This saves weight and provides stress and vibration help across a surface that epoxy alone cannot provide. I used curved hemostats to reach into the wing to lay up the fiberglass. I originaly found the wing flex when I held the assembled wing in the center and at the wing tip. I could see the covering wrinkling just outside the wheel well and that is why I decided that reinforcement was needed in this area. You can test this area on your own and decide if reinforcement is needed now or in the future. If your plane is exceeding specs in terms of speed or weight I would suggest you examine your options carefully. It is a great flying plane and has been shown to fly well with many engines and options.
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Old 01-24-2010, 09:29 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

The factory did address the issues of the weak firewall attachment and the weak area at the wing's gull bend. I had one of the early kits that lacked the reinforcements and, after reading of the firewalls pulling out after the first engine start on some of the early kits, I seriously beefed up my firewall. The airplane was a delight in the air but it only lasted 30 flights. The right wing outer panel blew off in flight and the model came down vertically into a corn field. All I could do was pull the throttle all the way back but it still hit hard. Interestingly, my beefed up firewall survived but the metal engine mounts broke! Also interestingly, the wing did not break at the gull bend so I must have reinforced the wing too by that time. (It was 4 + yrs ago and my memory is a bit hazy on the sequence of events.)

The two outer panels of the wing attach to a short center section with very short 1/4" ply joiners. These joiners work like a tongue-in-box both in the outer panels and the center section. Unfortunately the "box" parts are only made of balsa - the tops and bottoms are 1/4" square balsa and the "walls" are about 1/8". When the wing was under positive "G" from a loop, the outer panel was being pushed upward pivoting about the point of attachment to the center section. The part of the joiner that was in the center section box pushed its way downward thru the 1/4" balsa and 1/16" balsa skin. This 1/4" balsa was very soft and not suitable for what was in effect, a main spar. Those ply joiner pieces did not go all the way to the center of the center section either. There was empty space about 4" long between the two joiners inside that box. If the joiner had been a single piece of 1/4" (maybe even hard balsa instead of ply) that extended out both sides into the outer panels, it surely would not have broken either.

I took some close-up pics with my macro zoom lens on my 35 mm Pentax, drew a diagram and wrote a polite letter explaining how the failure occurred (my own little "NTSB" investigation) and my conclusion that the failure was the result of inadequate structural design. I requested a left wing, center section and fuselage so I could rebuild the airplane. Hangar 9 sent me an entire complete kit, free! I sent them a profuse thank-you note. To their credit, Hangar 9 is truly a stand-up company.

The new kit was updated from the first production run and had 4 hardwood blocks reinforcing the firewall/fuselage joint and a spar reinforcement at the wing's gull bend. The firewall reinforcement looked rather minimal to me, so I repeated the beefing up job I'd done on the first one but the spar reinforcement was almost identical to the one I had done myself on the first one. I was pleased with that, but I still made my own one-piece ply joiner for the center section.

I did something else, too. I'd used a Magnum .91 4-stroke engine and on the first model I mounted it the way they had provided for, with the cylinder pointing downward, not vertically, but at the "7 o'clock" position as viewed from the front. This had the effect of lowering the carburetor to a position very low relative to the fuel tank and it was not possible to lower the tank because the wing center was in the way. I'd had several flame-outs and deadsticks on the first model because of the difficulty of getting reliable top-end and idle needle valve settings with the effective high-tank position. So I mounted the engine in the new one with the cylinder horizontal ("9 o'clock" position) effectively raising the carb higher. The engine ran very much better this way. I have not seen a Saito 100 (H9's recommended engine) up close and maybe that engine runs better in the "7 o'clock" position than mine does but I recommend you carefully check how your tank position is relative to your engine's carb before you finalize the engine installation.

One other thing I discovered later - the Top Flight canopy for the Gold Edition Corsair is a very nice replacement for the H9 canopy, It has a better scale shape and the H9 plastic is rather more brittle. The TF one is not painted but the H9 is painted in the inside. I had put my switches and battery charge cables and the Voltwatch under the canopy and made it removable on mine. (I used two batts and two switches for redundancy). I'd have preferred to glue some small metal washers around the holes in the plastic for reinforcing where my little pins held the canopy on but the paint would need to be scraped away to allow the glue to stick the washers to the plastic. With the TF canopy, I could put my own paint on the outside and avoid that.

Another tip: Why do a test flight on a new airplane with the canopy and cowl on? Chances are, you will have to adjust the engine settings anyway and getting at the engine with the cowl on is a pain. You have to remove the prop (and spinner if the airplane has one) to remove the cowl. Get the engine set and the airplane trimmed and get it landing reliably before risking $50 worth of scale accessories. After it is flying and landing reliably, THEN put the scale stuff on and enjoy how pretty it looks. On my second F4U, I made my own wooden cowl with a hatch that can be opened without taking off the prop. Not only did that improve the operational convenience at the field, I was able to make it a lot stronger and more resistant to damage from the airplane going on its chin on landings.

Which brings up another point - most of the tail-dragger WWII fighters in model form often tend to go on their nose on landing, especially if you fly off grass. Most model kits have the main gears too far back. Worse, a lot of retracts only swing 90 degrees and point straight down when extended. I got the Sierra Precision retracts with the 100 degree swing to GET THOSE MAINS farther FORWARD. Robart also makes "back and twist" retracts with a choice of swing angles. Look at pics of the full size airplanes - the gear legs extend from the wing at a point very close to the leading edge. The Sierra units can't really be mounted as far forward as I'd like because the leg extends from the chassis at a point a good inch to the rear of the forward-most point of the gear's frame. Also, the leading edge of our models' wings is a pretty thick piece of wood that, itself, forces the gear to be mounted farther to the rear than would be ideal but I'd be reluctant to try to remove any material from what is already a weak point in the wing.

I also mounted my air tank and plumbing, valve and retract servo on the wing instead of the fuselage to avoid those darn quick-disconnects that torture my arthritic fingers. My structural reinforcements and air retracts made for a nearly 10 lb model, a little heavier than the first one. The first one flew light and was very nice in the air (when the engine was running and the wing was staying on!) The second one did not have as light a feel to it, but it still flew very realistically and was very pleasant to fly. It sure landed a lot better than the first one.

The designers initially made some poor choices in the structure but they have addressed this and updated the model. And they did do a nice job of making a good looking Corsair. WWII fighters can be really thrilling to fly (at least when you can avoid crashing or damaging your model on landing noseovers!) and the H9 Corsair is a BEAUTIFUL sight in the air.

I hope some of my experience is helpful to you so best of luck with yours!
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Old 01-24-2010, 09:50 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

Villa22:

I don't have the Corsair, but I have the H9 Hellcat powered by an RCGF 20cc gass engine. I love the engine and the plane flys fine with the gasser. But it is heavy and the stock landing gear wouldn't hold up. I installed Century Jet retracts, enlarged the wheel wells for 4" wheels. But I heavily reinforced the wheel well area. On my first Hellcat I didn't and a wing came off in flight. Hellcat No. 2 is doing great. Picture of failure to reinforce and also of No. 2 with same engine and retracts. Oh yes, to get it to balance, I had to build a battery box way back in the fuslage and put both the ignition and receiver batteries there. Also the gasser swings a 16-8 prop which looks more scale than the smaller props.
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Old 01-25-2010, 09:17 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

thanks bmustang i enjoyed reading your post and appreciate all the good advise innhave renforced my firewall and gull wings just in case. if it breaks at less i will know i did something.
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Old 01-25-2010, 10:34 PM
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Default RE: hangar 9 corsair needed fixes before 1st fight

You're welcome, Villa. One thing I would also recommend is to wrap the wing joints (the ones between the center section and outer panels) with fiberglass bandages. If I'd done that on my first one, the wing never would have come apart. So I definitely did it on the second one. I peeled back the Ultracote and used 2" wide glass cloth strips and, probably 30 minute epoxy. I add a little denatured alcohol when the glue is a bit thick and it smoothes out nicely, squeegeeing with an old credit card. Ultracote seems to stick pretty well to glass/resin where Monokote, in my experience, does not.

I better stop; the more I think about this the more I remember!

I hope you get a lot of enjoyment from yours.
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