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P-38J Engines? - 2/21/2003 1:52:47 AM   
zusie


 

Posts: 73
Joined: 10/18/2002
From: Tecumseh, MI, USA
Status: offline 		I am about to start to build a YELLOW Aircraft P-38J. As recommended I have purchased two Zenoah G38 engines to power the 38. A fellow flying friend suggested that I consider using 45cc engines instead of the G38s for safety! Anyone out there have any experiences with this P38 with G38s mounted? Other thoughts or recommendations would be appreciated.
jg
       Post #: 1

P-38..... - 2/21/2003 2:17:21 AM   
warbirdz1


 

Posts: 578
Joined: 8/7/2002
From: Pembroke pines, FL, USA
Status: offline 		Zusie......G-38's are plenty for the "Y" P-38....wing loading already is at the upper edge with G-38's.....G-45's would certainly add more power but with extremely high wing loads which are almost a certain "Death Spiral" with an engine failure......Have seen 3 or 4 "Y" P-38's with the G-38's and they flew well........Bill....

(in reply to zusie)
       Post #: 2

P-38J Engines? - 2/21/2003 10:01:52 PM   
zusie


 

Posts: 73
Joined: 10/18/2002
From: Tecumseh, MI, USA
Status: offline 		Many thanks Bill,
I'll stick with the G38s as you also recommended. That extra weight would be a killer, don't think my friend thought about that aspect--thanks again.
jack

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       Post #: 3

P-38J Engines? - 2/22/2003 6:19:01 AM   
Vince


 

Posts: 1650
Joined: 2/2/2002
From: Nederland, Tx.
Status: offline 		I agree with Bill, I have also seen several Yellow P38's fly with G38's. They are no slouches.

Vince

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       Post #: 4

P-38J Engines? - 2/22/2003 8:47:02 AM   
hanna


 

Posts: 168
Joined: 9/18/2002
From: Austin, TX, USA
Status: offline 		Why not Moki 2.10's. It seems they would fit in the cowls without cutting a big hole. Mike Krizan

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       Post #: 5

perfect engines are... - 2/22/2003 9:08:54 AM   
nemesis4u



Posts: 2033
Joined: 4/4/2002
From: Bryan, TX, USA
Status: offline 		Hey gang...go to [url]www.rcwarbirds.com[/url] and look for links...then goto EVO's hangar...he has a lot of pics and suggestions on installing ZDZ40's...they fit entirely in cowl...his website is unreal....just get a bucket out.,.,he even has his own private airfield...shares w/ friends.... over and out.....

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VQ WARBIRDS, KMP, & RCV

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       Post #: 6

P-38J Engines? - 2/22/2003 9:11:20 AM   
CaptainHook



Posts: 1095
Joined: 12/24/2001
From: Swartz Creek, MI, USA
Status: offline 		The G38's will fly this model at scale speeds with added nose weight, about 70 mph. Moki, not enough, although a great engine. G45, is probably a little better.


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Carey Hook

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       Post #: 7

Go w/ zdz 40's - 2/22/2003 9:14:17 AM   
nemesis4u



Posts: 2033
Joined: 4/4/2002
From: Bryan, TX, USA
Status: offline 		Speed was P-38....go w/ zdz's ....40's smoke em if ya gottem....it is fast w/ zdz 40's and they don't weigh much at all....go to the website...you won't be sorry....

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R/C WARBIRDS / RC TANKS ENTHUSIAST
VQ WARBIRDS, KMP, & RCV

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       Post #: 8

P-38J Engines? - 2/22/2003 6:50:28 PM   
Vince


 

Posts: 1650
Joined: 2/2/2002
From: Nederland, Tx.
Status: offline 		[QUOTE]Originally posted by hanna
Why not Moki 2.10's. It seems they would fit in the cowls without cutting a big hole. Mike Krizan [/QUOTE]

Because IMO they would use huge amounts of very expensive fuel.

Vince

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Can't keep my mind from the circling sky.

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       Post #: 9

Yellow P-38 - 2/23/2003 5:52:55 AM   
twinman



Posts: 1628
Joined: 1/19/2002
From: Katy, TX, USA
Status: offline 		While I admit, I have not flown the Yellow with G-38's, I have seen them fly at Bomber field with both the 38's and 45's and the increase in performance is significant with the larger engines, and several around here were changed to the 45's.
I agree with the concept to keep the engines mounted to avoid the carb hanging out the side and the rear mounted carb type engines handle that job, but at a price, in that the throttle linkage is more "Interesting to mount"..and the choke is Much More interesting. I used one servo for the chokes under the cockpit and a separate channel.
I also am using the ZDZ engines. One other idea instead of additional nose weight, is to make the back plate from steel. This balances the plane with the added benefit of lowering the idle speed. You can drill the back plate as necessary to lighten as needed...just keep it balanced!!!
As to using a smaller engine to avoid the "Spiral of Death", the benefit is marginal. The problem with the P-38 is that the rudders are small,the wing loading is very high, and the engines are very widely spaced. This is what caused the "Death Spiral" Been there done that with now four P-38's. Now use two gyros to slow down the unequal thrust to a managable level.
Remember that engine reliability is life to the P-38 model. Do not make the assumption that because you are using gas engines that reliability is not a concern......IT IS!!!
Told you twins make you crazy!!!!!!
Good Luck,
Twinman

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       Post #: 10

P-38..... - 2/24/2003 12:39:58 AM   
warbirdz1


 

Posts: 578
Joined: 8/7/2002
From: Pembroke pines, FL, USA
Status: offline 		TwinMan......Good Stuff......but you know alot of what happens with a twin can be put in one of several categories......certainly piloting skills has much to do with it......but engine failure is ugly regardless of who's flying when it happens at the most unopportune time.........say on T/O or a low pass or climb-out..........it seems like one can concoct any idea of what an engine failure might be like but until it happens/when it happens now its more reflex than anything.........as we have discussed that immediate(If not sooner) tendency to invert is a very "Rude" awakening.....unless a twins "Proven" single engine performance has been accomplished...its probably most prudent to reduce power and land immediately......the higher the wing loading the quicker the plane is inverted....thats why I think a balance has to be struck between performance and wing loading.......and your right...cant assume gassers wont have a problem.......I know first hand my "Z" B-25 "Doesn't" perform nearly as well as the "Z" P-38 under single engine ops...the B-25 goes upside down much quicker.....thats just another reason to increase aileron travel slightly on a twin...it might be alittle sensative but it also rolls back to wings level quicker.....from inverted.....then reduce power to idle and lower nose and land ..........

(in reply to zusie)
       Post #: 11

Twins - 2/24/2003 3:05:29 AM   
twinman



Posts: 1628
Joined: 1/19/2002
From: Katy, TX, USA
Status: offline 		to warbirdz1

I could not agree with you more.
However, ( there always has to be the However) in these forums, I tend to put in my two cents toward the idea that I am dealing with a novice in the art of twin or multi engine flight. Most people are not skilled in multi engine flight or set up, and I am not trying to give advice as to the fine points and skills that can only be learned by experience.
I this case, an underpowered P-38 will snap roll the first time you try to loop it. Is a P-38 as pattern ship? No, Will everyone who has it, try a loop, yes. Have had four and still flying two.
My points are to prevent the troubles ( Troubles can be defined as repairs or crashes) that I had learning to fly twins, and to assists others to avoid the mistakes I make.
As you can tell, most of my experiences are in the burn and learn catigory.( Now you know where the first two went) I got into experimenting to avoid and better the sport and share with others.
You mentioned increasing the aileron throw, but on a P-38, due to the small rudder size, I always use maximum allowable rudder throw.
If your Z B-25 is worse to handle than a P-38.....it is off my wish list!!!!
Good Luck to all and have fun.

(in reply to zusie)
       Post #: 12

P-38J Engines? - 2/24/2003 9:35:34 AM   
hanna


 

Posts: 168
Joined: 9/18/2002
From: Austin, TX, USA
Status: offline 		If the Moki 2.10 will fly a 90" 30 pound warbird how is it underpowered in a Yellow P-38 with 2 engines and about 5 pounds more weight. Cost of glow fuel vs. pump gas is not an issue for me. Someone posted the rpm and prop size specs for the G-38 and the Moki was equal or better. The reason I am asking is I am building a Yellow P-38 and it is going to have Moki 2.10 power. I talked to the Yellow reps and the Yellow company and was told this was good package for the kit. No big hole in cowl or spark plug hanging out. I have nothing against the G-38 or 45. Mike Krizan

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       Post #: 13

zdz40s - 2/24/2003 12:07:12 PM   
fw190d9



Posts: 499
Joined: 12/15/2001
From: Seguin, TX, USA
Status: online 		Zusie, I would seriously consider using the zdz 40s. I have put 11 flights on mine since I installed them and they are performing great. The plane is fast but not grossly overpowered. I flew it this past weekend at the Edinburg warbird meet and it performed flawlessly. If you do choose to use the 40s , email me and I will fill you in on the details of the installation. BTW, Twinman, are your 80s getting enough air with the gear doors closed?
Evan Q.
http://www.homestead.com/evoshangar/home.html

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       Post #: 14

Cooling - 2/24/2003 6:29:06 PM   
twinman



Posts: 1628
Joined: 1/19/2002
From: Katy, TX, USA
Status: offline 		I added the scale or slightly larger oil cooler flap under the nacell to created a low pressure zone to pull the air out and sealed the engines to the cowel.
As far as the Moki, if fuel is not an issue, then Yellow used to recommend the ST 3000 at 1.8 cu.in. and the Moki will be far beyond that power level,,,,,,particularly the G-38.
Good Luck.....send picutures to rcwarbirds gallery for the P-38's

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       Post #: 15

carb air - 2/24/2003 8:53:34 PM   
fw190d9



Posts: 499
Joined: 12/15/2001
From: Seguin, TX, USA
Status: online 		Sorry Twinman, What I meant was , Are your engine's carbs getting enough air. I ran into a problem with mine in that when the gear doors were closed, the open rear radiators were creating a low pressure area and pulling all the air out of the fuselage causing the carbs to run rich. Blocking off the radiator intakes and installing a small scoop on the insides of the nacelles solved the problem. The zdz carbs now get enough air and run reliably. This problem only showed up in the air when the gear doors were closed. As for cooling, my 40s are only showing a 170 deg cyl head temp after a 15 min full throttle flight.
Evan Q.

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