skubacb

Hi, michaelbbbb told me he was able to balance at 5" with no lead. But he has two batteries. One extra for smoke.

I will move the CG to 5 1/2" and see if I can move the battery further back.

MikeCam: Right now I have a Fromeco 2600 LiIon. Also, like you I have a 1.2V 4400mah in the servo tray for on board glow and it still took 5 oz to get to 5 5/8".

Looks like one could make a hatch further back in the fuse or use the tail wheel hatch to make a battery tray further back.

BTW take a look at this site for a very small and light onboard glow system: http://www.42-percent-products.com/glow-accessories.htm

Bob Paris

My Feedback: (13)

Hay jstanton,
I never heard of the Evolution glow plugs...heck...I didn't even know they sold glow plugs. I take it you like the plugs... : ). Ok...I'll try it out and let you know what happens. But I use the OS four cycle plug and K & B plugs with good results. The only time my engine quits is when I run out of go juice. The S.T. G90 has a nice sound...and I can't wait to hear how it sounds with a Bison muffler. I love the sound of a good 2 stroke engine at full power...and the S.T. has a sweet note.

I have the muffler your talking about. I never used it, because it wouldn't fit my "B" at all. From what I have been told it will work ok with the S.T. .60 and .75 . But not the S.T. G90...for this engine needs more exhaust excit or openings for your exhaust, then is supplyed by the stock In-Cowl muffler. I was told to drill a hole in the muffler...say start at 1/4" and slowly inlarge the whole until you get the RPM's your looking for. The stock muffler must create to much back pressure...and needs the added pressure release to give the G90 all its power.
Soft Landings Always,
Bobby of Maui

jstanton

My Feedback: (14)

Bob,

I have the OS 75AX I plan to use with the Top-Flite in-cowl muffler. I liked your K&B 100 installation so much I desided to use my OS 75AX becasue I already had it. The 75AX is one of the recomended engines for this plan. If it does not provide the power I want I plan to purchase the K&B 100 from MECOA in California.

f16man

I use the bisson pitts also works very good, the os carb is off of a os77 ducted fan engine , it has about a 2mm larger bore than the stock st carb. between the pitts pipe and the os carb I gained about 1500 rpm running a 12-8 prop, she sings pretty good for a ringed engine, ps; I run 15% cool power and os#8 plug.

Upward

My Feedback: (1)

I plan on using the OS .91 FX, I was wondering what type of exhaust I sould use. Pitts?
Do I need to mount this engine sideways to get the exhaust to dump out the bottom of the cowl? I would really like to mount the engine inverted.

All the inverted mufflers I can find looks small & im wondering if this is going to kill the performance when compared to the 90 degree sideways mufflers?
Thanks

f16man

I for one have never had very good luck running the larger size engines inverted, the oil seems to build up and put the glow plug out after the taxi out to the runway, but I'm sure others will chime in on this and prove me wrong, just saying after 25 years of playing with this stuff I found too many probs with inverted engines. The bisson line of mufflers are a good fit and are semi tuned to the engines they fit, I say that because no muffler can really do the job like a true tuned pipe [expansion chamber style pipe].The bisson pitts will dump out bottom and your engine will be mounted sideways, I know, I know it hurts to be wackin big holes in your cowl,but for me I would rather fly my plane than look at how pretty she is on the ground he he.

jstanton

My Feedback: (14)

I am using the Top-Flite in-cowl muffler for ay OS 75AX. This muffler will not work on your OS 91FX, but in the search of an in-cowl muffler for this P-51D I came across JTEC. They make in-cowl mufflers for the whole line of OS engines and i know they will have one for your OS 91FX. I have used JTED mufflers b before and I have one on a inverted ringed ST-61. The engine runs great and I have more power with it than I did with the stock muffler. I hope this helps

Upward

My Feedback: (1)

Just got mine in the mail today, Like I have read in many posts before it looks like a five year old covered mine. In Fact Im sure a five year old covered it. No way am I going to sign up for a wait list for another one, so I will try to iron out as many as I can. The tail feathers look to be the worst.

Bob Paris

My Feedback: (13)

Hay Jstanton,
OS usually makes good power, and I'm inpressed with my buddies OS .90 in his Mustang. He flys with a four bladed Zinger and it seems to do the job ok. Not real fast...but fast enough, and he ended up making his own home made in-cowl muffler for his T.F. P-51D.

This is my first large S.T., but flew the S.T. .23, for years, in many Little Sticks. I'm not sure what props I used to break in my G90, but I installed a Zinger Pro 15x4" for the first flights on my "B." I would rather have a good solid pull and not a lot of speed for the first flights. I also have Zinger Pro 15x6~10" props too, and will try that after I get comfortable with the model. When I was breaking in the G90, I was amazed at its power, and its half the cost of an OS .90. To be honest, I'm not sure what prop would be best for this model...so any experieced advice would be nice.

Soft Landings always,
Bobby of Maui

Bob Paris

My Feedback: (13)

Hay Upward,
A buddy of mine is flying his with an inverted OS .90FX. The engine runs great inverted, but I do not know what glow plug he used...I'll ask the next time I see Lenny. He was not able to find an in-cowl muffler to fit his model, so he made his own, and used alum. welding rods to weld it together. Its a tight fit for sure, but there is room. The OS .90FX has plenty of power for this model and this modeler uses a four bladded Zinger prop too.

Soft Landings Always,
Bobby of Maui

Bob Paris

My Feedback: (13)

Hay F16man,
I have had mostly bad luck with inverted engines...but my last project was a F-82, and I used two Fox .50's. These engines drove me nuts, and eventually I went with Perry carbs & pumps. Nothing seemed to work on those Fox engines for me...nothing. When the engines were running, the model was a rocket ship, and if flys just great on one engine. More then half my flights ended up single engine and I ended up just short of getting out the old 12 guage and putting the engines out of their missery. I eventually pulled the Fox .50's and installed lighter engines...side mounted.

I prefer to side mount my engines in scale models and use a pitts style muffler. I was not inpressed with JTechs G90 inverted muffler that I first used on this model. No mounting hardware was given with JTechs muffler and not any where as nice as Bissions inverted muffler either. I ended up buying the side mounted pitts style muffler from Bisson, and I also like their attention to detail.

I was surprised how stiff Sigs P-51B cowl is, and the scale exhaust is built into the cowl. The exhaust area is solid fiberglass and cloth and well painted too. I repainted the cowl today with T.F. Luster Coat Paint...but I'm not real happy with the paint. The paint will melt and deform your canopy, and the paint is effected by temp. and humidity. It came out ok, matches T.F.'s covering well and now the fuse is ready to fly.

Soft Landings Always,
Bobby of Maui

Upward

My Feedback: (1)

Bob, thanks for the advice.
I do think im going with the OS .91FX Inverted with the Bisson or Jtec Inverted muffler.

I do want to say I spent over 4 hours going over my model with the iron and everything came out almost perfect. It looks great now. I would highly reccomend ironing this model after you recieve it.
The hardest part was the Fuse silver monocoat, it was alot more trouble than the olive.

devens

Sounds like if you want to use a .91 fx you need to either build your own muffler or try the j-tec if you want it in the cowl. I am interested to know if anyone has tried the j-tec on the .91 and if it fits in the cowl?

tiger650

My Feedback: (22)

Is anybody using the new OS FS-A 110 in their P51. I just received mine and I am not sure what prop to start ot with. Any thoughts would be appreciated.
thanks!!!

jstanton

My Feedback: (14)

Well I just finished my P-51D today and I will post some Pic's when I get back home from work. The OS-75AX and Top-Flite in-cowl muffler fit inside the cowl and looks great. Very little cutting of the cowl. Just enough for the engine head and exhauts. I am getting 10500RPM with a evolution 13x8 prop and it producing 9.5lbs of thrust. The plane weigh's in at 9lbs 6oz and I did not have to add any weight to balance the plane at 5 1/4" for the LE at the Fuselage. With a 1 to1 power to weight ratio she should fly pretty good and that is all that I want

I'll post some pics of the maiden flight ASAP

Bob Paris

My Feedback: (13)

Hay Jaston,
Good to hear you finished your model. I like the RPM figures...thats a lot of prop to be spinning that fast. I do not remember what my RPM figures were with my G90...but I'll know soon enough. Tower sent my wing by boat...not airmail like I paid for...so I will not see my wing until after Christmas. I finished my Fuse on my "B" and now installing my wing servo's. The retracts are installed and with any luck...I'll be covering soon.

Monocoat is not easy to apply...at least for me. I was lucky, and the fit and finish of my model was near perfect. Infact taking off the covering, allowed me to see how they covered the rudder and tail feathers. I just duplicated what I saw, and I it came out ok. I use both the iron and heat gun. I also use a soft glove and iron socks...my old socks...: )...works like a charm. It takes time...and lots of smaller pieces. I've yet mastered the art of Monocoat application, but I'm trying. I've Monocat on models that are over 20 years old...and the models are still flyable.

Soft Landings always,
Bobby of Maui

mike early

Keep us updated on that engine. It seems you are the only one that owns one yet.

tiger650

My Feedback: (22)

Will do. I will be installing it this weekend. With the help of my LHS I decided to start out with a 15x8 APC prop. It is a beautiful motor. I hope it runs as good as it looks. I have also decided to put in the Sullivan onboard glow.

CorsairJock

My Feedback: (90)

These 'Stangs are subject to some torque roll at lift-off and whenever they are powered up at slow speeds (kinda like the full scales). With an engine/ prop combo such as your's: I suggest that you be very ready to apply lot's of (right) rudder, and suggest less than full power for take-offs. Not trying to put anybody down, I just wouldn't want to hear that you crashed it on your 1st take-off (or ANY take-off for that matter).

BTW: I read that a number of the 1st U.S. Merlin powered Mustang pilots had previously been flying P-38s (with contra-rotating props), and several of them, un-accostomed to the torque roll effects of the Mustangs, learned all to late a very deadly lesson about those torque effects.

lbrande

My Feedback: (16)

I was told by an ex P-51 pilot that the way he learned about torque roll was that he was told by his instructor to go to 10,000 feet and practice an approach, i.e. flaps, gear down, and correct engine settings. When you are settled and ready to "land" apply full power to simulate a aborted TO. Lo and behold the next thing the pilot knew was that the plane flipped over due to the engine torque.

Lew B

CorsairJock

My Feedback: (90)

lbrande, Yeh: I heard that one too. One scary way to learn about torque roll, but better than learning the way those ex- P-38 pilots did.

MANFRED

My Feedback: (27)

DOn't forget most of those pilots trained on single engine, stearmans, texans then onto P-40s or P-47s. The P-38s made a few widows as well when one of the engines would crap out on takeoff. Charles Lindbergh actually figured out and trained them how to avoid torquing in, He taught them with an engine out situation to drop the throttles and glide it in. Better than rolling over I guess.

tiger650

My Feedback: (22)

I agree with what you are saying, and you can add to that P-factor. Because the prop is dramatically inclined to the path of flight in the P51, the descending blade has a higher angle of attack relative to the ascending blade, thus creating asymmetric thrust. As I recall P-factor is also proportional to speed. The higher the angle of attack and speed the more pronounced the yaw from P-factor becomes. So it's really later in the takeoff roll that you should be really careful. It's a good idea in most tail draggers to get the tail wheel off the ground early in the roll to better align the prop with the flight path.

Upward

My Feedback: (1)

I was wondering what type of servos to use with my P-51D
Pneumatic Retracts: Does it matter what kind of micro servo I use?
I currently use a futaba FM PCM system.
I am just getting into flying, and do not know what Im looking for (servos).
I have experience flying trainers, and a Pen Knife.
Please explain why I would need the type you reccomend.
Thanks

Bob Paris

My Feedback: (13)

Hay guys...
I fully agree that you need to be ready with right rudder on take off. My P-47 needed right rudder on the take off, and also during climb out, untill my speed was up. It was a Lanier P-47N, with a .61 in the nose, and torque was a factor using a 13x6 prop. I also found that different model fighters...needed different rudder inputs on take off. None were the same...but as I progressed into larger models...more rudder input on take off became an issue.
Soft Landings always,
Bobby of Maui