A Look at the H9 Twist 150
Review by: Jim Moss

One of our club members (Jim Moss) decided to give the Hanger 9 Twist 150 and Evolution 26 GT a try. The aircraft went together easily only taking a few hours and it balanced perfectly with the 26 GT engine. We had some difficulty getting the engine to fire up the first time. In fact, we ended up using an electric starter. Then the engine fired up quickly We ran the engine precisely to the Instruction Manual. After a brief break-in (probably 25 minutes) it was loaded up and taken to the field for the maiden flight. I noticed the the Ignition LED Indicator light was blinking fast. The engine wouldn't start. Jim looked up this LED indication in the manual, and it said the voltage was too low. Jim installed a 5 cell 1000Mah battery, and we only ran it for about 20/25 minutes. I put my battery checker on and it showed 90% charge at 6.3 volts. We packed up the airplane... Later on, Jim looked in the Evolution website and found that the Ignition REQUIRES a minimum of 6.4 VDC to run. That explains the problem we were having. In order to get any flying time at all the ignition battery needs to be a 6 CELL pack! While this sort of sucks, it's a fixable issue. I can't imagine why a 6 cell pack would be needed in this day & age of advanced technologies! Especially when everyone else is using 4.8 and 6.0 for theirs. OK, we'll get past this and get this bird in the air!          

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This photo is showing the break-in sequence. The engine is run at various speeds for specific times. The engine really runs nice! It's a little on the rich side, and will stay this way for at least several flights. Jim is having a Triple "A" 6 cell pack assembled and it will be installed soon.

At this moment, I don't have any flights to report as we are waiting on a 6 cell battery pack. While the Ignition Module does have some nice features such as remote tach indicator and battery level, I really prefer running a 4.8 volt battery pack. Maybe Evolution will consider changing to a "more standard" Ignition sometime.

It's difficult to justify this engine with a street price of $399.99 and not even getting a muffler of some sort. In the range of 20 to 40cc, there's a lot of engines to choose from! I'm not saying this engine isn't worth the money, but four hundred dollars is a lot of money for a 26cc engine.  Here is a review of the  MVVS 1.60 Petrol Engine found in the Just engines Site.

UPDATE: 2/11/07

Jim was not pleased with the current muffler as it would spray exhaust all over his wing, making a mess. He purchased the Tune Pipe assembly for the Evolution hoping this would eliminate the mess as well as add a little more performance.

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The Tuned Pipe really worked well. Jim gained over 1000 RPM and the wing stays clean now. Here is a comparison:

17x6 APC 8400 9450
18x6 Zinger - - - 9030


We had to use a starter for the first run of the evolution 26cc gasser.  Once started, it ran great and restarted with a hand flip.  However, there is a bulletin out on the 26 that says to use a 6 cell battery for the ignition.  I was using a 5 cell and it didn't last very long.  The ignition needs a minimum of 6.4 volts or the ignition will not fire.  If these manufacturers want to push small gas engines, they're going to have to rethink their ignition modules.  I remember the small Zenoah G20 I had for a while having a thirst of 500 mah per 10 minute flight.  I compare these small engines to the 50cc gassers, particularly the DA ignitions, who run either 4.8 or 6.0 volt. and minimal mah usage.  As far as the evolution 26 goes, to keep the weight down, Russ is building me a 6 cell pack with AAA cells.  Hardly weighs anything at all. The twist has been flown on a couple of days now and it handles like a big trainer. Very easy to fly, good roll rate, tracks straight.  Spins are a little slow, but we'll see if we can't change that with some C.G. movement.  Landings are slow and controlled.  The evolution 26cc. gasser that is powering it has done a very good job, extreme fuel miser, and my only complaint is, I have the engine mounted up-right with the muffler throwing oily exhaust on top of the right wing and horizontal.  This can be cured by simply mounting the engine inverted or as I did, order a tuned pipe that will not only exit the exhaust farther back, but should add a little power at the same time.  The plane hovers at about 3/4 throttle and is very stable. At the present time, I'm using a 17 X 6 apc prop and getting about 8500 rpms, but after the tuned pipe arrives, I'll experiment with an 18 X 6 wood zinger. The evolution engine on the pipe seems to be putting out the same power as a same size O.S. 1.60 on nitro. On the ground, the throttle on the evolution seems linear and I haven't seen any discussion on the net about the engine being peaky in the air.  Do you foresee the evolution having a more normal power curve in the air from the shape of the pipe.  The evolution pipe, except for the section attached to the header, has a constant outside diameter, much like a straight pipe.  The expansion chambers I had on motorcycles had a fat section in the middle and were peaky.  Your tech site information about the pressure wave was informative, nice job.  I guess we'll just have to take our planes out and find out.  One nice thing, I'm saving money on windex.

Flew the twist 150 today with the new pipe and 18 x 6 zinger prop.  The evolution 26cc engine started easily and throttled up quickly.  Flying wise, the plane is VERY docile and on high rates, does 3d aerobatics easily.  A 7 to 8 minute flight only used 3 to 4 ounces of fuel.  The muffled tuned pipe looks mean, but I think its one of the quietest exhausts I've used.  The performance increase over the stock pipe was substantial.(around 9000 rpm's on the 18 x 6 prop).  Landings like all twists are slow and easy.  
I'd rate this project high for those who want a gasser, good performance and easy to fly, and depending on your vehicle,( somewhat large airplane) you can transport it without a teardown.

As part of the review of this engine and plane. Here is the "everything new" build cost for anyone who might be interested in starting this project or something similar.  As we all know, the final cost is a long way from the sticker price on the pretty box at the store. 
Evolution engine -        $400
Tuned exh. pipe -           100
Twist 150 plane -            250
(2) mpi switches-              40
(2) batteries     -               50
(4) digital servos-           220
(2) analog servos-            60
synthesized receiver-      130
propeller            -              20
servo extensions-               30
Well, thats the end of this endeavor, we'll see whats lurking around the corner for a next build.