RE: KMP Corsair
 

I just made the plunge. Found one out here in Singapore. (I am an expat out here) I have a YS140 that will work nicely in it. I look forward to hearing a flight report.

-JDEWOLFTX

RE: KMP Corsair
 

Good luck on the flight report, I think this is a build only kit. :D Been 6 months and no one has gone up yet? I want one bad but I need to see some reports before I go for it. Kepp plugging away, sooner or later we should hear about a lift off..

Shane

RE: KMP Corsair
 

Just finished mine, and setting it up for the maiden asap, but the 15.8-16 Lb. All up dry weight I came up to is having me concerned, its actually a pretty small wing area for a plane of this weight. It finished off at 37 oz. per square foot with the weight I arrived at, which surprises me considering that KMP states this plane up to 17lbs. when using their retracts. I put around 2 oz. of lead in the tail cone to offset the Brison and components up front and fine tune as much of the C.G. shift as possible which occurs when these heavy retracts come down. Had to do a lot of reworking and repositioning of radio gear whilst making use of the limited area in the fuselage and trying to minimize use of lead. One thing for sure, putting this bird together, was a major pain in the arse! Unlike other arfs i've come across before, many irritating surpises and lots of kit bashing was required, not really my thing, so good luck everyone, and wish me luck too, hope this thing flies lol. I am looking forward now to an RC Guys Pitts special, as KMP has slapped the taste of warbirds out my mouth for some time to come. But don't get me wrong, this Corsair looks really nice in my opinion, which of course is why i sunk funds into it. Now i can only hope she flies as good as she looks, quite like this chick I know but anyways.
Peace out!
Louie

RE: KMP Corsair
 

Come Loiue you have to elaborate ?? I have the plane still gathering parts and finishing other project ect .(Fw190)
In all my rotating gear warbirds I balance wheels up -upside down , I know you probably did the same . As we all know doing this does present a slightly nose heavy situation when the gear is down . But this has never presented a problem in 6 -P40 and 2 H9 Corsairs .
I know the KMP scale wheels are heavy , so one change I was considering was going to the big dubro light weight wheels , I just dont know that I want bench the KMP wheels they look toooooo good

RE: KMP Corsair
 

Those pics look great! It makes me want to get going on mine. I am sure your maiden will be great. That motor will sure pull that plane around with authority. Small wings yes, but a heck of a power plant!

-Jdewolftx

RE: KMP Corsair
 

Thanks Jdewolftx!

LDM,
Setting up the c.g. with a corsair or more particularly a warbird with fore and aft retracting gear is new to me. The thing about it that gets to me is the amount of additional nose down I initially got when the gears were deployed. Yes, i tuned the C.G. settings with the gears retracted (in the wings) wherein i achieved close to level perhaps slightly nose down balancing, but when the gear was deployed (gears down for landing) and using the kmp retracts and wheels provided, the amount of nose down i got was honestly very close to if not at 30 degrees, and it seemed considerable but as i said, its new to me. LDM, since you have experience with fore/aft retracting gear models if you say that is an acceptable amount then that would really make me feel confident about the issue. But what i did to fine tune my c.g. balance settings was to add a little lead in the tail, just enough so, such that when the plane was inverted and on the balancer with wheels retracted, i added just enough to get the plane leveled to a point where, the center chord of the horizontal stabilizer was just a tad higher than being level with the floor, i hope that elementary explanation makes sense, but my idea was to get as close to being perfectly level without taking the c.g. back from the specified 130mm in the manual. After doing this, i guess it slightly minimized the amount of nose down when the gears are now deployed to maybe 15- 20 degrees as oppposed to 30. Overall, it helped some, but still looks concerning. I agree, the wheels look very nice, but they arent exactly lightweight either.
Louie

RE: KMP Corsair
 

In my experience 16-17 pounds on an airplane this size would be just fine Tisoy909. I currently fly a Thunder Tiger Sea Fury which is only 68 inches in span and weighs about 15.5 pounds. Not sure of the wing area but probably around 800 square inches. Flies like a dream and is actually somewhat of a floater without the flaps. I've also flown the 70 inch span Ziroli Jug at over 17 pounds and it too was a fantastic flyer. I don't know what your flying experience is but, assuming you have some previous warbird time, I wouldn't be too concerned about the weight of your Corsair. Best of luck with it, it looks like a very nice bird.

RE: KMP Corsair
 

do you know of any videos of it flying. I was thinking of going with the Saito 170 R. I heard that the KMP gen V Retracts have a leaking problem at the vlaves and lines. Any word on that.

RE: KMP Corsair
 

I just found out that my YS140 that I had ordered will actually end up being a YS160. Anybody planning on using this motor? I assume that same weight, stronger motor is not bad but I hear that the 160 is a bit tougher to get running smoothly.

As for the retracts, I didn't have any leaky valve issues but you can feel the difference in quality vs. Robart. I did have a slight bend in the shaft that the wheels are mounted on and this resulted in the wheel rubbing against the strut. Was pretty easy to bend back. I may end up replacing the plumbing with Robart stuff anyways.

-Jdewolftx

RE: KMP Corsair
 

The nose down angle increase with extended gear is not a very usefull measurement because this can vary depending on how far away from the fuse the ballancer is positioned. The nose down angle with extended gear will be greater as the balancer is moved to a part of the wing that puts the balancer pivot point closer to the vertical C.G. of the Corsair. For example, the nose down angle will be greater when the balancer is positioned at the wing root than it will be when the balancer is postioned further out at the gull-bend in the wing because the gull-bend in the wing is further away from the vertical C.G. of the Corsair. So, don't be concerned about the nose down angle with the gear extended. That angle is not really indicative of anything. A more indicative measurement is how far forward the C.G. moves in mm when the gear is extended. If you are measuring your C.G. at the wing root, I would guess that the C.G. isn't moving forward more than 10mm with gear extended which should be fine. I don't know what the chord of the KMP corsair is, but for reference, the H9 Corsair has been flown successfully at C.G.s ranging from 33% to 40% of the wing's chord at the root.

The C.G. shift is noticable on my H9 Corsair when I operate the gear in flight. After take off and retracting the gear I have to reduce up elevator input a bit to maintain the same climbout angle. I've done this so many times that I make the adjustment unconsciously, but it can be a little disconcerting if you are not ready for it. This adjustment could be mixed out but if your gear doesn't retract really fast, you'll need some sort of delay on the mix.

RE: KMP Corsair
 

Louie ,
Craig is dead on , I have never had a problem with my planes useing the method described by Craig and ending up with a slight nose down cowl when measuring the cg .
As far as the cord method of CG , when I have measured my CG on cheapy arfs that have bad plans , I use 25% of max cord close to the fuse as my starting point , this has never failed me .

RE: KMP Corsair
 

Craig-RCU & LDM,
First off, I just wanted to thank you for taking your time on this issue to help me out on this. Let me first explain what I have assembled for purpose of balancing the plane. As you know the gull shape of the wing wouldn't permit me to balance the aircraft in the same easy manner we would with other planes, e.g. Mustangs, Spitfires, P-47s etc using the inverted method. Just going about balancing this bird I felt that I had to assemble a specific balancer, so i came up with this somewhat rudimentary contraption you see in the first pic. I put together a few pieces of 2x3 and connected them, then used the drill press to setup holes which supports a pair of rounded rubber tip dowels to protect the wing surface. I arranged them in such a way where they would sit at the top of the curve on the wing to avoid lateral pressing of the dowels and make contact at a perpendicular angle. I set masking tape on the wing and penned in the 130mm line. Initially, I thought the planes pitch with the gear deployed was around 15-20 degrees, but after checking this again, I now believe this to be somewhat less but as you can see from the photo, still noticeably angled as compared to when the gear is retracted. Because of the dramatic nose drop i got with gear down upon first balancing I added a little weight into the tail, bringing the tail down a little further. I brought this tail drop to a point where the horizontal stabilizer was closer to level with the floor but still a tad above from being completely level with the floor. With this setting it may appear slightly tail low but I am still under the impression this is okay as long as the horizontal stabilizer is at or slightly above being parallel with the floor, but even my own opinion is a little disconcerting , so i just wondered whats your honest input on this? Craig, In your explanation about how adjusting the distance of the balance points from the fuse gives varying pitch readings with retracted and deployed gear, I am still trying to fully understand as I see these two balance points to lay on the same axis of pitch, but I will take your input for fact in that I should try to find a means to more closely place the two dowel tips to the fuse. However, from these photos can you guys tell me if these are acceptable amounts for a maiden attempt or should I retry balancing again? thanks for your time and help in advance guys.
Louie

BTW: I measured the Main wing chord length at the root and got roughly 400 MM, so with the factory specified 130 MM c.g. that I set the balancing line with on the tape, this came out to a 32.5% of max chord length.

RE: KMP Corsair
 

Tisoy909 don't worry it will be all right. Just balance the plane with the gear retracted. A little nose heavy makes it land better anyway. You will have less tendency to bounce your landing. We have always balanced rotating gear with the gear up (retracted) and it has always worked.

One trick for making a CG machinie is to take a round 3/8" or 1/2" wood dowel if you can find it thay have half dowels at some store if not take it and rip it in half. Now take a length of it as long as needed and tape it to the wing at CG and where you want to measure it at flat side to the wing. Then I make a frame out of PCV pipe to where there is two pipes that run front to back and set that on the table. Now lay the plane upside down so that the dowels are riding on the pipes. Since they are round they will just pivot on the pipes. Cheap easy and works really well on any size plane especially giant scale. Wish I had pics but I am not at home. Hope you get the idea.

RE: KMP Corsair
 

I think you guys are making the balancing act a little to complicated......I know, I used to do it too until I learned about this::::::::::

What I am about to show you may change your entire way you look at balancing a model........

IT is called a Venessa RIG....... Very easy, can be made out of almost anything and can balance a light weight foamy to a FULL SIZE AIRCRAFt!!!

It is all explained in this post
http://www.rcuniverse.com/forum/m_70..._3/key_/tm.htm

Some guys just balanced there planes by suspending ther planes in there pcv bulding stand!!!!

Hope this gives you some good options!!!

RE: KMP Corsair
 

Tisoy909,
I was just trying to say that you shouldn't be concerned over the nose down attitude with the gear deployed. I tried to explain why, but if I didn't explain myself clearly enough to be understandable don't bother to try to decipher what I said because it is really irrelevant at this point since it looks like you've done a good job with balancing based on your pictures. The span-wise spot that you picked to balance your Corsair is good and you shouldn't bother with balancing at a different span-wise point on the wing. 32.5% should be a good C.G. for the maiden. Based on the H9 Corsair C.G. range that I mentioned, you might be able to slowly experiment with more aft C.G.s after a few flights.

RE: KMP Corsair
 

Tisoy looks good to me my friend , you did a nice job , I like the slightly nose down and 32% sounds good and in range .
I make my own balancers as well and use cheap school eraser tips on the ends of the dowels

RE: KMP Corsair
 

32% is way too far aft!!!

closer to 25% is better!

RE: KMP Corsair
 

I do mine slight nose down, dry, with gear up.

RE: KMP Corsair
 

Does anybody have experience with the larger YS engines? I am putting a YS DZ 160 in mine and I have read that most people use Hyde mounts or some other vibration isolation mount for the larger YS's. Is this really necessary for the Corsair?

-Jdewolftx

RE: KMP Corsair
 

Go to warbirds.com , look up Richard L , the YS engines are his favorite choice , he can tell you what you need to know

RE: KMP Corsair
 

Yes it is and also be sure your firewall is secure.:D Also, here is a tuning bible. ;) [link]http://www.probuild-uk.co.uk/factsheets/ys_engines.php[/link] Learn it, love it, hate it, but print it and keep it with you. Following this guide will ensure a flawless tune. Just be sure to use the recommended fuel or you will experience poor running especially idle. I use CoolPower 30% Heli blend and it works great. They are incredibly powerful motors compared to motors of the same class.

Hope this helps,

Shane

RE: KMP Corsair
 

Richard is the one who I turned to and he knows his @$#% with these motors.

Shane

RE: KMP Corsair
 

Thanks for the reference and the link to the "bible". I have some experience with larger Saito's but where I am living now, the club is really pattern focused and it seems everyone is flying YS. I knew that they were good engines and I figured that having all that support at the field was probably a good thing to have. I am an american expat living in Singapore and surprisingly, you never see Saito's out here. When you mention them, the people here seem to think that they are difficult motors. My experience with my Saito 150 is that it was one of the least difficult motors I ever used.

In any case, I will keep the bible with me and get this motor tuned in. The good thing about choosing a motor they all use is someone even offered me his old, giant scale extra to put the motor into and fly for a few weeks so I could get the motor nice and broken in BEFORE it ends up on the Corsair. This will make me a lot less nervous during that first flight.

-Jdewolftx

RE: KMP Corsair
 

N/P on the bible. I agree with you about the Saito's, I break mine in slobbery rich then tune and leave it. Unless I will be doing a little winter flying. Good luck with your maiden.

Shane

RE: KMP Corsair
 

To jdwolftx, I currently am flying with YS-63s, YS-110s and YS-140s and have always used a Hyde Soft Mount. I find that I can get at least 150 or more flights with a set up and I don't have to change any electronics due to vibrations. The YS motors have a tremendous amount of torque and the Hyde soft mounts isolate the vibration and it doesn't carry back to the fuse. I have used the soft mount on 3-D aerobatic and on all my war-birds. My batteries last a long time as well as the servos since they are not fighting the vibrations to keep centered.