mytuneport

I have noticed a lot of discussion about the CG on the latest version of the Cermark F16P. I have a friend that is pretty sharp when it comes to putting models into cad and calculating the CG. I have the latest version of the F16 and he did and cad drawing of it and figured the CG to be about 7 ½ inches from leading edge at root. I tend to start out flying my planes a little on the nose heavy side. The first flights of my F16 had the CG at 6 11/16 inches from leading edge. I don’t believe in using my little fat fingers to pick up the plane when checking CG location. I use a tape on both wing roots with a rule marked off in 1/4 of an inch and a stand I made to get a pretty accurate location of the CG. Something I learned from flying my A7 prop jet, that has a long nose, is to be sure you have plenty of stabalator throw to keep the nose high when the nose heavy plane gets slow. I have the stab. Throw on my F16 set a 1 7/16 inch, considerable more than the instructions suggest. My F16 will keep the nose high at low landing speeds. I intend to move the CG toward the rear a little more and see how it affects its performance. Something you might keep in mind, if you balance your long nosed airplane with an empty thank, then you are going to fly a nose heavy plane when you leave the runway with a full tank of fuel. The farther away from the CG the tank is located, the worse the nose heavy condition. I checked the weight of my F16 with a very accurate scale and it comes in at 4350 grams or 9.59 lbs. It is powered by a Jet 90L and I have it propped a little lite, 11x7. The Jet 90 L turns the 11x7 16000 rpm on the ground. had to check it with two different tachs. WOW. The plane still goes like a bat out of ---- and sounds like a Indy car when it goes by on low, high speed pass. I intend to try a 11x8 next time out. My current F16 is the Thunderbird paint scheme, and I now have a gray paint scheme in the shop now. I really like these planes.

PS: I want to thank my friend TXKflier for doing the test hop on my F16, I suffer from diabetes and sometimes my vision gives me a little trouble. Thanks to TXKflier, the first flight went off without a hitch.

phjoker

My Feedback: (4)

I am glad everything went good. The 7-1/2" C.G seems to be it on the new version.
On another note For those of you who have the general dynamics scheme I have for sale on RCU
a vinyl set of decals to replace the waterslides that come with it.

sbrackets

Was that CG of 7 1/2" with the landing gear up or down? And was the fuel tank empty or full?

Thanks, Jim

phjoker

My Feedback: (4)

Gear Down and the tank empty

mytuneport

My freind and I got curious about just how much the CG location changed with a full tank versus empty tank. Well we took the time to check it out and found that when we filled the tank on my F16P it moved the CG forward 7/8 inch. Have not thought much about the gear being up or down and the CG. I guess we will have to put the plane back on the stand and check it out.

vasek

My Feedback: (4)

This plane is a bit confusing as to the CG location. On most planes, the CG is measured while the gear is UP if the gear retracts backwards (a-la P40 or Corsair). In this case tho, since the gear retracts FORWARD the CG is measured gear down (as joker did). I thing much confusion regarding the CG on this plane is due to people measuring the CG gear up.

Sniper.308

I disagree, the manula that comes with it seems to have the wrong CG printed in it. There are a lot of inaccuracies with the manual. When I was reading through it before I started building I noticed the parts are different on some. Others missing all together because they have made upgrades, which is great but update the damn manual. I decided to put things where they looked like the went and pretty much chucked the manual. Mine will make it's maiden flight this weekend if it isn't windy or raining. My new X9303 is in so I'm really anxious to get things programmed and back into the air.

sbrackets

Hey Guys
I got my Cermark F-16P today. Looks good, no damage from Fedex shipping Looked it all over pretty good, It's a really nice kit. Just looks a little tight inside the fuselage to work on things. Hope you all have small hands.
Anyway just thought I would let you all know that I received mine and will start the build sometime in the future. I need to get the engine and servos yet.
Will keep you all updated with my progress.

Regards, Jim

hummingbird111

cool,,, i love this plane ,, can't wait to get a Jett 90.

vasek

My Feedback: (4)

Sniper, I know the 3rd edition manual has the cg misprinted. What i'm saying is sometimes you can get the cg wrong even with the right info due to the retracts swinging the other way. I wasnt saying that YOU had it wrong because of that.

cheers, V.

Sniper.308

Just out of curiosity, what PSI are you all using on your retracts. The only way to get mine to go up on a stand I have to use 50-60psi and that sounds relly really high, but I have no pressure problems. If I go less than that they barely go up and against a wind they wouldn't at all. So let me have it.
Jason

hummingbird111

I usually put around 40 psi on avarage and get about 4 good up-down cycles..mabey 5 sometimes,, you may have some blockage in your lines or the little thingy that the lines plug into in the rear of the plane,.

Robert Groves

ppl are using up to 130 psi
I think I will settle for 100, I get about 8 retracts at that pressure.
Your figures are same as mine @ 50-60
If you got the restrictors with the plumbing, you will need them or the wheel end up banging up. I got 4 restrictors with the plumbing and have used one in line with each retract and the 4th on the main supply line from the valve. Works great.
BTW are you having problems getting the wheels to retract properly? I have had to bend all 3 struts. As it stands now, all three are sticking out from the fuse by about a half inch? I am hesitant to bend the mains any more as they will then be at an angle forward on landing?

Thanks

Rob

Sniper.308

Well that makes me feel better about the pressure cause I swear my manual says 15psi. That's a major misprint. I'm only having problems with one retract not going up properly. But I think I fixed it with a little teflon lube. I was thinking about putting larger tires on it, does anyone takeoff/land on grass with the stock wheels besides me?
Jason

vasek

My Feedback: (4)

100 psi is the norm

phjoker

My Feedback: (4)

Yes 100 psi is the normal. Funflyer f4 and myself fly off of a grass SOD farm so its a thick grass with no problems at all.
on mine I put the same size nose wheel as the mains 2 1/2" so it gives me a little more nose high stance for the take offs

gsoav8r

My Feedback: (6)

Im sure my manual stated something like 15 psi also. But having used retracts before I knew it was wrong. I did try 15psi just for kicks but the gear wouldnt even cycle. 100 psi is the norm as stated previously.

Im able to fly my bird of turf with stock sized wheels but the grass is kept really short so I havent had issues.
Cheers.

Sniper.308

I was going to test fly mine today but I had two other to maidedn first and didn't get around to it. I had an rx lockout on my todat. my X9303 and a AR6200 in my H9 Spit locked out inverted, lucky for me it grabbed again. I hit the wrong switch for my retracts and thought that they did not work, oops. I had to shut off the engine and belly land when I did not even need to. I think what happened was I had both my rx's facing wingtip to wingtip horizontal, nothing vertical and it went into failsafe and then caught again. L U C K Y!

Robert Groves

Well, My bird is just done after 5 months.
Nothing like waiting months for delivery and having to source missing stuff cause cermark wont replace it.
Lookd pretty good, cant wait to get her in the air!
My ST90 and Ultrathrust pipe seem to be working well. Fits just great!
No real big building issues.

Can anyone assit with gap sealing?
I am new to sealing hinge gaps, but I have put about a 1" strip of tape along the bottom of the ailerons and on the rudder.
Someone mentioned that they seal gaps cause it looks better???? Cant even see mine, is there another way of doing this on the top of the wing so you cant see the gap?

Thanks

Rob

phjoker

My Feedback: (4)

I don't think alot of people sealed the gaps on this plane. I know I didn't . I would say if you sealed the bottom
gaps you should be fine.If you want to seal the seal the top just for the looks I don't think it will hurt anything??
I don't know how you did the bottom, but I would do the tops the same way?

gsoav8r

My Feedback: (6)

Rob,
I used a somewhat color matched self adhesive vinyl film that just about blends in. This is easier to me than trying to iron in thin strips of moneykote or ultracote. To me it looks better because I cant see thru the gaps now. The most noticeable improvment IMHO was the rudder, having sealed both sides.
Cheers.
James

evan-RCU

James, you know the field is closed but we have a better temp field?

gsoav8r

My Feedback: (6)

Hey Mr. Pres!!,
I sent you a pm.
James

Robert Groves

[img][C:\Documents and Settings\rg\My Documents\Bluetooth Exchange Folder\Plane\Spinner\SP_A0083]
[img][C:\Documents and Settings\rg\My Documents\Bluetooth Exchange Folder\Plane\Spinner\SP_A0085]
[img][C:\Documents and Settings\rg\My Documents\Bluetooth Exchange Folder\Plane\Spinner\SP_A0086]
[img][C:\Documents and Settings\rg\My Documents\Bluetooth Exchange Folder\Plane\Spinner\SP_A0087]
[img][C:\Documents and Settings\rg\My Documents\Bluetooth Exchange Folder\Plane\Spinner\SP_A0088]
[img][C:\Documents and Settings\rg\My Documents\Bluetooth Exchange Folder\Plane\Spinner\SP_A0089]
[img][C:\Documents and Settings\rg\My Documents\Bluetooth Exchange Folder\Plane\Spinner\SP_A0090]

I seem to have the spinner lined up with the front wall. There is a little right thrust which seems correct. I am concerned with the amount of "up" thrust there seems to be relative to the nose of the fuselage.

Does everyone elses look like this???

Thanks

Rob

PS Thanks for the sealing hints James.

Robert Groves

Here they are.