Eric.Henderson

This gets more interesting to say the least.

OS shows two different, other than normal atmospheric venting, crankcase vent uses on a couple of their 4-c's.

In one application there is actually a nipple on the inlet manifold that is connected directly to the nipple on the crankcase. (A 91 Surpass I believe)

In another application the crankcase vent is in the back of the crankcase and goes directly to the muffler. (The FL-70) They claim it gives more consistent fuel flow in all attitudes.

Today I ran the motors and actually flew! The plane was very clean afterwards BTW.

Whomever said that this plane glides like a set-of-keys did not appreciate what a pair of three bladed props would also do the keys in flight. It dropped like it was in an elevator without a counter balance. I only just saved it with a blast of full throttle before the "boing!". I had to repair/replace the torsion blocks which apeared to have had almost no glue on them. Lesson learned...

This is a strange twin to fly. The attempt to make it flyable on one engine with severe side-thrusts is obvious in the turn. Adding a little rudder like when you fly a Cub seemed to do the trick. It looped pretty well but was a dog in the Knife-edge position. I doubled the rudder for next time :-) The rolls were adequate but dropped a lot in the KE positions. Definitely not as good as I had hope.

Now here is a bit of an oddity. The Mosquito weighed 12 lb 11.6 oz dry. The TWINSTAR weighs 6 lb 10 oz dry. Both planes are using the same engines. The Mossie was clearly faster and had better vertical, lbetter oop tracking and size etc, I'm thinking that the two side thrusts must be fighting each other and slowing it down a bit??.

It should be warmer tomorrow so I will try a faster/more-throttle approach for landing as advised above. And I have rigged a flight-mode option where I can drop one motor to almost idle with the snap roll switch. Shoud be fun, at least at a great height.

Anyone spun these things with any degree of severity and success?

Regards,

Eric.

motoracer212

Eric was that the Twinstar that was up at Airport hobbies? You beat me to it. Could you post a schematic of your twin tank setup. I'm interested in doing the same. I only get about six minute flights with the stock setup.

Mike.

Eric.Henderson

There were two Twinstar kits at the store. There was one left after I left. :-)

I don't have a sketch.

The tank set up is very simple. BTW, you could add a tank the same size as the one in the nacel and get 8 oz of fuel easily.

1. You connect the first tank (the one inside the nacel) clunk-line to the carb.

2. You connect the vent-line to the clunk-line of the second tank.

3. You connect the vent-line of the second tank to the muffler.

To fill, just fill through the line that goes to the carb. The tank inside the nacel fills first. Then you see the second tank fill up and you stop. No need to disconnect the vline that goes to the muffler.

Regards,

Eric.

thinairflyer

My Feedback: (40)

I bought my TwinStar when they first came out (5 or 6 years ago?) I had two broken in and absolutely reliable OS .46FX's on hand and so installed them on the TwinStar. Aware that the model was greatly overpowered I flew it VERY CAREFULLY, no full throttle passes down the runway (full throttle reserved for passes well beyond the runway) no hard pullups, no snap maneuvers, etc. Handled it gently all the time. It was clocked at 125 MPH full throttle on several passes. MA 10x7 props. 4 minutes max and then onto the runway with those 4 oz. tanks.

It was easy to tell the wing loading was up there with the .46's it had a very nose up attitude when slowed down. I flew it with a Futaba 8UA radio and after synching the engines mechanically, fine tuned the sync by EPA and mixing point. You can choose the mid throttle mixing point with the 8UA, so was able to get the engines in perfect sync from mid to full throttle. What a sound! The .46's were turning about 15,300 on the ground on 15% fuel. In the air they screamed!

Great fun to fly!

Now the bad part of using such large engines the model was not designed for:

Noticed one flight (about 30 flights total or so) that it felt funny as it passed center field at full throttle; throttled back and landed noticing the right wing felt heavy. The covering had blown off of two rib bays on top of the right wing about mid span, this plane was just not meant for this speed and vibration. (both props always were balanced, just quite a bit of vibration at low RPM with such a large engine) Fixed it and continued to fly it regularly.

Next noticed I was losing control surface hinges (the CA type that came with the plane) Installed the flat, pinned nylon hinges on all control surfaces. No further broken hinges.

Next noticed up around 50 flights that ribs were coming loose in the stabilizer (engine vibration I believe) Not enough loose to stop flying, just kept a close watch on them.

On a very windy day at a field at 7,800' a friend had driven 70 miles to watch the Twin fly. I should have left it on the ground, but Hey! it always handled the wind well and I have never minded flying in the wind so lined up and at about ten feet down the runway, the wind was blowing so hard straight across the runway it weathervaned the twin straight across the runway. THAT WAS A CLUE FOLKS!

Lined up again and with full right rudder and full left aileron and full throttle it went straight down the runway and lifted off pretty as you please. Flew around with just a little bumping form the wind, no real problems in the air.

Lined up factoring across the runway some to reduce the crosswind component (still 90 degrees to the runway and blowing hard) and back to about 1/4 throttle (now I mean the wind was BLOWING) and sure enough when the twin was about 3 feet off the runway I got a wind gust that almost knocked me off my feet. It just stopped the twin dead in the air. It stalled the left wing and hit there first and cartwheeled across the nose. I thought it was totalled but was very surprised to see only minor damage to wing tips and fuse at the wing saddle.

This was about flight 55. In all those flights I never had an engine stop. I on several occasions pulled one engine or the other back to near idle with channel knobs on the channels I use for throttles and flew it with reduced power on one side. It still handled pretty good.

About that time, I was busy getting my house ready to sell when I retired and then building a new house in Colorado, so the TwinStar is waiting on me now to rebuild it. It is stripped of the stick-on covering to have the ribs repaired and the crash damage fixed and then I will recover completely with monocote. I also plan to mount two small fuel tanks on the center of the wing and use the nacelle tanks as header tanks to increase the flight time. I getting anxious to get her back in the air!

< Message edited by thinairflyer -- 11/19/2005 10:08:27 PM >

Pneuman

Update!

I just thought I would come back here with a quick update on my "sideways" installed hinges. They are holding in great, and showing no signs of breaking. I look at them and tug them after each flight and so far-so good.

I'll be switching them in the winter for sure to the correct way.

In the meantime, I sure do like my Twinstar. What a rush to fly!

Thanks,
Pneuman

Flight Hawk

Has anyone tried or thought about converting the upper end engines for this plane to diesel for longer flight times? I understand that this may be costly. But it's a thought.

I'm currently building one with (2) super tiger 40's.