hambone1

I would like to start off by saying this thing is VERY nice for $99. The plane is ready for retracts with very little work. The split flaps are not that bad to install either.
OK , that said,I am wondering if the engine is supposed to be offset to the left 2-3 mm.The plans show it(but dont mention it). There is 1 horizontal line for the crank center. On the firewall there are 2 vertical lines, 1 through the center and 1 offset. Which do I center the engine mount to?

hambone1

OK so I installed the mount off set . I went to put the nose on, it seams as though the nose wants the engine up 3/8 of an inch or so higher to fit correctly. I raised it 1/8 and will see how it flies.
I am also missing some small hardware( I will start another thread).

hambone1

After talking with others on here, they said it wouldnt be a big deal to move the engine up as long as the tank wasnt going to go below the carb. With the engine inverted , that gives you plenty to work with.
This picture is AFTER movin the engine crank center up 7/16 ". Looks much better now. That is a 3" spinner from Tower, $5-6.

Included a picture to show the quality, and easy access to modifications.

hambone1

Here it is balancing. One problem though, they call for the CG @ 90MM. After an extra battery stuffed in the nose(retracts), I have the CG @ 95MM. Will this be ok , or is it absolutely critical to have it at 90?
I would probably just try it if I didnt spend so much time on it....
Thanks guys

opjose

Nice job.

A 5mm difference is not going to be noticible in a Warbird IMHO.

I normally move the C.G. back anyway on many of my planes to get a bit better response and less of a nose down tendancy when flaring... of course you do not want to go TOO far...

The offset to the left is used to compensate for right thrust.

2-3mm is a pretty low offset. I don't have this model... (but after seeing yours... I just might)... but that sounds like you have LESS than 2 degrees of right thrust, so everything sounds about right.


Raising the engine normally adversely affects 3D planes to a small degree.

When the engine is higher than the centerline, there is a more (but slight) tendancy for the fuselage to move out of the flight line during a roll.... e.g. rolls are not quite as axial.

A high dihedral warbird has this non-axial roll tendancy anyway, so you would not see any effect, especially since the 3/8 difference is SO small.



Many people also overstate the tank to carb values... remember this is most applicable when the engine is idling on the flight line to prevent siphoning... if it were a huge problem in flight, we'll you could forget downlines and uplines and 3D would be a mess without a pump, etc... ...tank ABOVE engine in downline... tank UNDER engine in uplines...

Another thing that is often overlooked with these warnings is that with warbirds and other tail draggers, the nose of the plane is pointed UP further ofsetting the tank to carb position until the plane is just about to lift off.

Yeah there ARE reasons not to get the carb that far from the tank height, but don't sweat it so much, it's not as dire as the "sky is falling advocates"... usually the tank/height problem is brought up whenever someone is having problems with an inverted engine...

In this case, it's the engine tuning that needs to be properly adjusted, and it's almost NEVER the tank/height issue which is to blame.... I've been through this many times myself... so much so that I'm now pretty used to tuning the engines inverted and I tend to mount them that way for cleaner looks on almost all of my planes...

When the engine is inverted there seems to be a smaller tuning "window" IMHO which you must hit... once done and the engine broken in, though the planes fly fine.

hambone1

Great, I was hoping someone would say that. This thing weighs a ton already. Unfortunately I will have to wait untill spring to try it.
After hearing all your experiences with the ultimate I reall want one of those, I would like to see it in a 60 size. I will only be able to hold out so long for it
Thanks for all your great advice.
Hey so clearcote will hold on pretty good even if you dont scuff up