Three bladed props would give you more pull at the expense of top speed. That could be a good thing for the Twinstar. Four strokes are really nice, I've got a big Saito 1.80 in my IMAC plane. Nothing compares to that sound. They are a killer on the budget as you said though. I'm not sure that 30's would be enough either since four strokes weigh a little more and have less RPM's. The .25's were turning between 10-11 grand with 9-6's and that was probably the minimum I would go. Any less power and the plane won't fly with an engine out. Maybe the extra diameter of prop the four strokes can spin would make up for the extra weight and less RPM's. Not enough experience to say. Whatever you decide the Twinstar looks and flys great. Enjoy!

Jim

Hi Jim, started the build last night, its a very well made plane imo however some of the creases and air bubbles in the covering were a little disappointing, did you have to smooth yours out? also do you think its worth using two smaller servos on the two throttles ie a hitec HS56HB and modifying the aileron servo so you can have two servos on the aeilerons letting you use flapperons? ie both aeilerons also serve as flaps? but keeping the weight down with the smaller throttle servos? or not worth the hassle?

I used standard servos on the throttles, but that's what I had laying around. The linkages are really short for the throttles, so as long as you make sure nothing is binding I don't see any problem with your idea. Saving weight is always a good thing in my book.

On the ailerons, just my personal opinion, it really wouldn't be worth it. The Twinstar only has thin strip ailerons and I don't see them being very effective as flaps. Also, as I'm sure you know, when the ailerons are deflected down as flaps they don't work very well as ailerons any more. I've tried flapperons on a few planes over the years and really disliked the loss of control. The only time I use them now is on sailplanes as speed brakes. They can be really useful in this mode for killing the glide and getting down quick, but you have to be able to fly the plane with your left hand/rudder only.

Yes, unfortunately my Twinstar's covering required a significant amount of attention. I've seen worse and I've seen better. The problem I think is that these models are constructed overseas and have to endure many environment changes. By the time we get them the variations make the covering sag and such. Here's a trick you may not know that I used. Put a sock on your covering iron and turn it up as high as it will go. You can use an actual sock, the ones they sell, old T-shirt, etc... Start rubbing down the loose areas over solid balsa. Start by keeping the iron moving constantly and then slow down gradually until you get a feel for what speed you need to get the right concentration of heat on an area. My Twinstar really looked nice when I was done!

Jim

yeah dont think i will try the flapperons idea as i did some research on it and you are correct its not a good idea, glued the wing together today looks to be a very very strong unit!! yes the covering is dissapointing but lets not forget its not an expensive model and you get alot of "bang for your buck"

Three bladed props would give you more pull at the expense of top speed

the three bladed prop is one inch smaller in diameter ie I run 9*6 well the three blade is 8*6 so would that still effect top speed?

You're correct, I think the rule of thumb when switching from two to three blades is to drop an inch diameter to get the same loading. I was taking that for understood, sorry. What I was getting at is that even when you equalize the loading by dropping the inch, the extra blade creates more thrust at the expense of more drag from the extra blade. In theory that would give you more pull in tight maneuvers and less straight line top speed.

In reality it's not that simple and some field experiments are in order to see what the actual results are from the change. I've seen it work good in some applications and be unflyable in others.

I think Jim I will stick with the two bladed prop.. I have the wing finished and the fuselage, all I need is to install the electrics, I found a little trick to the whole thing, use 24 hour epoxy and it makes you build sloooow which means you dont tend to rush and make mistakes...............like today's effort was to glue the nacelles in with the motors........

There simply was not enough clearance between the clevis and the engine crankcase no matter how I bent the wire to get free movement

I like the concept of fast links however this is one are the kit is let down with this style of wire/tube I would have preferred the system of plastic ribbed tube outer and inner I gave up in disgust tonight fitting the throttle linkages, i will look at it tomorrow just read your review

running the pushrod wire directly into each link

and are trying to work out what you exactly meant by this???
Im going to sleep on it but are considering using some balls and links from my parts box (i fly helis too) to space them off the motor a little I will let you know if it works

ok then no photo yet but yes the ball link worked perfect!

I'm glad that worked for you. I think I just experimentally bent the wire this way and that until there was no binding.

my one and only gripe about this kit is the parts bag of screws......there is not enough!! had to raid my cupboards to finish it, what are screws worth? why not just put some extras in the kit??

Now that you mention it, I think I remember having to raid my screw bin as well. I'm so used to changing a few things out in included hardware bags, I guess I didn't think much of it and didn't mention it in the article. Most of the hardware was just fine though which is a plus. Let me know how it flies.

Will do that mate I also had the small brass pin/clamp for the nose wheel not have a threaded hole to clamp the control rod........fixed with a 4 mm tap but and is a small thing but still a real pain to sort out considering what the part is worth .......but its STILL an awesome plane....taxied around the lawn on Friday and the sound of those two motors resonating off each other was awesome

I agree. The realism and quality of experience really goes up when you hear those two engines throbbing together!

I have heard a few folks talk about tuning issues with twins and resonance well im just about ready to get things going (winter here) and our local hobby shop told me to avoid tuning problems mount the motors with the heads not vertical but slightly pointing outwards like a "V" he said to me with twins you can get both resonance issues and tuning issues with both motors , another point did you tach both motors wide open or not bother?