Hey All,
I'm about to test fly my GiantScalePlanes Spitfire MK II with a YS 110. The building of this ARF was straightforward, especially with hints from the RCU Mag article. However... After mounting my motor, I'm a bit perturbed by the incredible incidence of Down and Right thrust built into the Firewall. Without any washers, mounted straight on (the firewall), the down thrust and right thrust seems a bit extreme.. maybe 5 degrees and 5 degrees... (sorry, don't have an incidence meter to check) Anyone have this kit? Does it fly well with so much correction? Am I just getting old? Should I zero-zero and start from there?
Any comments?
Thanks!

I'm also putting one together with a YS 110FZ.





I don't think the amount of down thrust and right thrust are extreme. My GSP Hellcat has the same down thrust and right thrust built into the firewall, and it flies great. Even with all that down thrust and right thrust, the Hellcat still requires two clicks of right trim and several clicks of down trim to fly straight and level.

I've taken out my washers to correct for the extreme downthrust and now I'm back to GSP specs on the down. I think what bothered me the most is that when I fitted the cowl flush with the 3 1/2" spinner backplate, the whole nose of the plane looked visibly crooked to the right! I've cut the right thrust in half and will see how she flies. (I'll be ready to change it back if flying needs lot's of trim...) I've read lots of threads here in RC Universe on thrust angle and guys seem to be very emotional on whether or not it's important... As a full size pilot, I'm very happy to have trim tabs on my controls and I think I'd like right and down thrust on my models.. the question is, how much?

Richard,
Your pics are great! Close up and clear... nice.
Stupid me, I put the YS muffler on my Spit, cutting the cowl out like a termites nest. Your pitts muffler is the way to go. Good on you!
Went to the flying field to try my right and downthrust but my brand new YS 110 would not idle; even with my 31 years of RC'ing, 5 hours of help from my flying field buddys and their 100 years of cumulative engine experience..
So.. I've got a bum engine. No Joy... Here's the bird... hanger grounded.
Please post when you fly.. good luck and thanks for the pics..

Bummer. It's rare to hear that a new YS 110 would not idle. Both of mine achieved a nice stable idle after running through a 14 oz tank slobbery rich on the bench:



I did have to lean out the low end a little bit to get the engines to idle when they were mounted inverted. I hope you know that counter clockwise on the low end needle valve = lean and clockwise = rich.

I'm getting close on my Spit. I'm waiting for a set of custom pneumatic retracts with 1/2" diameter oleo struts from Century Jet. The wheel wells have been enlarged to take 3-3/4" diameter wheels.

So did you get your engine problem resolve yet?

I got the left retract with nice scale size wheel installed into the wing:

Great looking Retract.. How much were they and did it come with the bend or did you have to bend it yourself?
I'm grounded. My Brand new YS 110 is about to be shipped to YS for service... 1st time I've ever had a bum engine out of the box.
Hey Richard.. Could you take a photo looking straight down on the front of your Spit from mid canopy to end of spinner? Just want to see if yours has a noticible "right" bend from the extreme right thurst built into the firewall... Mine looks a bit weird...

I sent Bruce at CJ a very detailed diagram showing all the measurements, and he just made these retracts to my specifications for $250. The struts come with the bend, and they were bent forward 4° by CJ just as I specified. Note that on a stock wing, the struts are bent forward by 5° (this is true for other Spits too). Since I enlarged the wheel well openings to take larger wheels, the center of each wheel well got shifted back a little, hence the 4° bend.

I will take a photo looking straight down on the front from mid canopy for you. My nose is slightly tilted to the right too, but it's not too bad since I aligned the right edge of the cowl to the right edge of the spinner.

Here is a pic looking from mid canopy to the front of the plane:



My nose looks pretty straight from this picture.

Below is the diagram that I sent Bruce over at CJ. He can make you anything if you give him all the necessary measurements.

Yeah, looks real straight from your pic... Guess it really doesn't matter when it's flying 3 feet off the deck at 70mph.....
Well, my ys 110 got Fedex'd to the YS service center today... This is the first motor in 30 years of RC'ing where I couldn't solve the issue... oh well... I'm just praying they don't come back and tell me the motor's fine... ouch.
Anyway... I liked your diagram you sent to CJ... very clear and straightforward.. you are a precise builder...
What plans do you have for detailing... The wings are pretty boring with just the painted coverex... I drew in panel lines and paint chips throughout the whole bird... Like to have my warbirds look used..
please keep me informed of your test flight and any more pics would not only be useful to me, but, any other RC'er wanting to build this nice kit!

Have you flown yet? I'm trying to get out to the flying field today or tomorrow... Got my motor back from YS... They said it had a cracked valve cover... right out of the box..
Oh well... here goes..

I took mine up for its maiden flight today, and you were right, the plane had too much right thrust. It took half of available left trim and all available down trim to get the plane to fly straight and level at half throttle. This plane was very fast at half throttle, and it flew great. It was a floater on landing, even with full flaps deployed. I came in with one or two clicks on the throttle and 30° flaps, but the plane still came in like a rocket. I think I can chop the throttle a little bit earlier next time. The plane had no tendency to tip stall at low speed while I was trimming it out up high. I will do a stall test next weekend. Here are a couple of pics taken after the maiden flight:

Richard,
Congrats on your maiden flight! You know, with all the work you put into those lander gear, I thought you'd at least have gear doors or wheel covers... I went to install them but being and ARF, ther gear covers would not be flush with the wing and I wasn't about to go digging into the spars to countersink the gear...
And... speaking of right and down thrust. I ended up keeping the down thrust as per the kit, and halving the right thrust with spacers before the first flight. Again, flew straight as an arrow. You said you had to trim both left and up? go figure.
My motor got serviced by the YS guys in Nevada.. took only 3 days and the YS110 came back purring like a kitten... turned out my motor had a crack in the valvecase...from the factory!
My flight was fantastic! Except for the nose overs... I think I'm going to take the advice of the guy that said to set her down in a 3 point landing... slow and almost stalling in... I didn't do any stall tests... let me know how your bird handles on that.
One thing I did notice... coming out of a powered loop, the elevator seemed a bit sluggish... took a little more input to complete the loop... like the "y" bend control rod was giving a bit under stress... What are your experiences?
Good luck with your Spit!
Dave

I have added a 1/16" thick strip of brass under the right engine mount against the firewall to remove some of the right thrust. Hopefully that will remove some of my left aileron trim. I will try to install gear door covers. The stock covers that came with the kit no longer completely cover the wheel wells since the wheel wells have been enlarged.

Before you attempt a 3-point landing, you might want to do a stall test to see if the plane will tend to drop a wing. You don't want any surprises while bringing the plane in slow for a 3-point touch down.