Ziroli P-38 proper CG (Full Version)

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P38J -> Ziroli P-38 proper CG (2/25/2002 10:53:29 AM)

I'm just about finished with my ziroli P-38 an I have two Questions that maybe someone can answer for me. First off I thought that I remember reading some were that the CG that is shown on the plans is incorrect and needs to be moved forward, If anyone knows where the correct CG is located please let me know. my next question is, Ziroli say to locate the CG with the gear extended, won't this make an already tail heavy plane even more so.



Edwin -> Ziroli P-38 proper CG (2/25/2002 6:11:34 PM)

Dont know about cg location on ziroli but I am currently building a wing mfg P-38. The gear on mine swing forward when extending. I would think that would move a little weight forward instead of rearward. Shouldnt make it MORE tail heavy. Or is it too early in the morning for me? Would be interested in your cg answere. When I move up to giant scale the ziroli P-38 will be right up there with the 2nd or 3rd project.
Edwin



CaptainHook -> CG (2/26/2002 7:46:06 AM)

I built one a few years ago. I dont remember the correct CG on it. I did talk to Nick Jr. about this, he mentioned that his dad did like tail heavy planes. Ray Harris out in Cal currently owns the one I built. He has flown this many times and could give a good answer. He is a member here at RCU but I cant think of his user name. You can try the the email of [email]RcP38Drvr@aol.com[/email] Good luck!

Carey



warbird_1 -> p-38 cg (2/28/2002 6:59:44 PM)

yep, you have it right. AFTER i sold my p-38 because it flew like crap, i found out the cg is wrong. i was affraid of wadding it up. i talked to two other guys in ohio at dayton and they told me that the cg has to go FORWARD 1 INCH which will make it more nose heavy . i hope this helps and i'm sorry i got rid of mine



ptrotter -> Ziroli P-38 CG (3/1/2002 2:27:25 AM)

Warbird_1,

Did they happen to mention whether the CG whould be checked with the retracts or down? The instructions say down, which is counter to normal procedure in most planes.

Paul



warbird_1 -> Ziroli P-38 proper CG (3/1/2002 4:21:14 AM)

i would say to keep the gear down per instructions just move the CG forward 1 inch . as i found out a nose heavy plane will fly back to you , a tail heavy one most of the time ,won't. when i shut down the power on mine i lost all control . it just mushed forward without contol. i flew it back to the runway at about 1/2 thottle then killed the power and PUSHED the nose down to get it to land . i had a pucker factor of about 8.6 *



CaptainHook -> Ziroli P-38 proper CG (3/1/2002 5:54:16 AM)

Nothing worse than a high pucker factor.



AirRayInc -> Lightening cg (3/1/2002 9:40:42 AM)

When I picked up the plane, and put the first dozen or so flights on the plane, I found the plane very very nose heavy. I found myself making high speed passes to set up for a landing, before I got the guts to start moving the cg more aft. ahhhhh, so nice. Unfortunately, I have the plane all broken down, as I get up the funds to upgrade the booms to the fiber glassed ones. I am going to assume that the plane I own was set up nose heavy, more so than the plans say. Flight performance was there was not alot of change when flying through gentle climbs and dives, but heavy pitch changes required alot of stick inputs prior to moving the cg back.

If some one posts what is on the planes, I can do a pretty good guess ti mate as to where I think my plane is at.

My suggestion would be follow the leads above, move the cg forward, watch your approach pace, as in keep it fast. The plane will bleed alot of speed with gear down, props throttled back and flaps once you get over the numbers. Later start moving it aft VERY SLOWLY, and you will find a nice balance, and be very surprised at how slow you can bring the plane in and be able to flare as well.

Best of Luck,

Ray



jkeze -> P-38 CG (3/1/2002 11:08:28 AM)

I built mine two years ago and put the CG where it was shown on the plans with the gear down. Got 50 flights on it and landings and although a few less than graceful ones I think the CG location is just fine.



P38J -> Ziroli P-38 proper CG (3/1/2002 12:32:13 PM)

Thanks for all the replies I think I'm going to be safe and start with the CG a little forward first and then slowly move it back. Thanks once again. the plans say 5 1/2" back from the leading edge at the center pod with the gear down I'll try 4 1/2 to start with.



warbird_1 -> Ziroli P-38 proper CG (3/1/2002 5:07:36 PM)

smart move. i was with nick when he flew his p-38 at kirkwood ny. i was really suprized how slow the thing flew landing! i asked him later about the CG and he said he thought it was a little nose heavy . good luck with your bird. ron



F4u5 -> P-38 #2 (3/3/2002 8:06:25 AM)

I have some thinking to do on CG. This is an odd discussion. I bought the P-38 that choook built and I found it to be a great flyer....Carey can build! I then swapped it to a very happy swapee.....that's Ray...aka A.R.I.... I love Colorado in the summer. Now I find that after kicking myself for swapping the P-38, I just had to have another. So, in about 2-3 weeks, I will be meeting the guy who bought warbird1's P-38 discussed and pictured here to become my P-38#2....now that's an odd set of circumstances....gotta love this hobby. Sounds like I will have some CG checking to do.



AirRayInc -> Jeff (3/3/2002 8:37:20 AM)

Hey Jeff;
I have to smile.... don't let the next one get away from you, there is nothing like the face of spectators when you fly a twin. Add to that the gorgeous sound of slightly muffled exhuast in sync and you have a wonderful start to great hops, as you already know.
I plan to upgrade the engines from g45s to g62s. Maybe once I get it all back together we can meet up in Colorado and do some formation flying.

Ray

Teaser.....



F4u5 -> Ziroli P-38 proper CG (3/3/2002 9:49:40 AM)

Hi Ray....nice in flight shot.....mmm mmm good



CaptainHook -> Ziroli P-38 proper CG (3/5/2002 6:43:34 AM)

I have tears in my eyes.



warbird_1 -> Ziroli P-38 proper CG (3/5/2002 9:01:11 AM)

real nice pic of the 38 makes me want to build another one



AirRayInc -> Love it (3/5/2002 9:19:13 PM)

Had a couple of email questions,
there is another option for the Ziroli Lightening, and that is the oe put out by Robart. It is a fully composite presentation, which cuts that build time 10 fold overall. And factor in your time and effort to build the wood kit, the price is pretty reasonable as well.

Should I ever retire mine, (not sell) I will pick up the Robart kit. One personal thing I like about the composite, is that I could get in there and really beef up the booms, prior to build up. There is an inherent weak area, just aft of the gear doors, that takes alot of punishment on landings. I had the same problems on my Bert Baker, Yellow Aircraft and it is the reason why my plane now is at the maintenece depot....... no, my repeated hard landings had nothing to do with it all, so just put that thought out of your head. I dont care if you were there when it happened, thats not not why.......(in denial apparantly)


:D
Ray



P38J -> Ziroli P38 boom fix (3/5/2002 10:41:11 PM)

On my first P-38 after 3 landings, none of them particularly rough my booms cracked. when I was taxiing back I saw the tail was just bouncing up an down. My fix was to reinforce the crutch with carbon fiber around the sides that I could reach, and the most important part was to change the way that I attached to top hatch. It needs to be tied in to the aft fuselage at the top and to the firewall this way it carries some tension loads on landing and keeps the crutch from being overloaded. after that modification I had no more cracking. On my second P-38 I replaced the hard balsa crutch with a spruce crutch without the carbon fiber, that seemed to work fine also as long as the hatch connected as I stated above.



STUKA BARRY -> Ziroli P-38 proper CG (3/6/2002 10:14:07 PM)

HEY P-38 PILOTS, I WAS WONDERING IF ANY ONE HAS EXPERIMENTED WITH GYRO'S ON THEIR BIG TWIN. I'M PICKING UP GLASS BOOMS THIS WEEKEND FOR THE CBA MODEL'S 120" W/S P-38. I WAS TOLD THAT THE RUDDERS ARE'NT THAT EFFECTIVE AT SLOW SPEED, AND WITH AN ENGINE OUT SITUAITION, I WAS TOLD DISASTER AWAITS. WOULD GYRO'S BE OF USE IN THESE SITUATIONS, OR ARE THEY NOT WORTH THE EFFORT AND MONEY? WAS ALSO WONDERING IF ANYONE WAS USING COUNTERROTATING ENGINES? I KNOW THIS IS IMPOSSIBLE WITH THE ZENOAH LINE, BUT WHAT ABOUT THE IGNITION ENGINES? JUST CURIOUS.



Edwin -> Gyros (3/6/2002 11:24:04 PM)

Excellent write up on that very subject in the
[url]www.rcwarbirds.com[/url] forums. In a nutshell, its a good thing. But read about his experiments, very informative.
Edwin



STUKA BARRY -> Ziroli P-38 proper CG (3/7/2002 12:01:54 AM)

THANKS A LOT!



warbird_1 -> Ziroli P-38 proper CG (3/7/2002 12:17:35 AM)

IF YOU CAN'T GET ANY GOOD CONTROL FROM YOUR RUDDERS MANUALY THEN THE GYRO'S WON'T DO ANY BETTER . IF YOU PUT C&H IGNTIONS ON THE G-62 I DO BELEIVE YOU CAN RUN THEM COUNTERROTATING. OR BRISON CAN HOOK YOU UP . I HAD Q-42'S CR ON MINE, THEY SUCK!



P38J -> Ziroli P-38 proper CG (3/7/2002 11:11:55 AM)

Zenoah engines are very easy to reverse rotation on, I just had to order the ignition for it from C&H and Install per the directions and instant counterrotating engines. as for the gyros I,m tring them for the first time after reading twinmans articals at [URL]http://www.bcflyers.com/sys-tmpl/gyrosforairplanes/[/URL]



warbird_1 -> Ziroli P-38 proper CG (12/24/2002 6:21:17 PM)

f4u i sent you mail , warbird_1



warbirdz1 -> P-38.... (12/25/2002 12:23:13 AM)

Gentlemen...Merry Xmas to all.......The P-38 flys fine without adding counter-rotating engines or gyros..........If the weight/balance is correct and the airplane is powered correctly...no problems should be encountered........It will fly fine on one engine if the case might arise.........Brison 3.2's or G-45/G-62 is in the area of good powerplant and performance.....If its at all possible,the less complicated an airplane is generally the less problems will have to be dealt with.......Bill..... :D :D



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