buzzingb

My Feedback: (2)

I want to put a Tower 75 in a Shrike 40 and need advice. I have already moved the firewall back one inch and mounted the battery in the very rear of the fuse. I think the motor and mound will just fit in the airframe. If any of you have experience stuffing large motors in Shrikes lets hears it.

Flyboy Dave

My Feedback: (21)

That's gonna be one bad hot rod....[sm=thumbup.gif]

Ernie Misner

Hey Dave and all, my friend's nearly new Tower 75 seems to run rich in the midrange and was giving him deadsticks because of this. Wadda you think? And what plug is best?

Thanks,

Ernie

aussiesteve

It's not in a Shrike but it's in a very similar Model
I have a Super Tigre 75 in a Green Models Delta 40

This model has dual rudder servos which I have set to turn both rudders outwards to act as speed brakes for landing (Right Rudder turns right & Left Rudder turns left) - This makes it a whole lot easier to land. It also had an additional servo for the nose wheel but it got too hard to work out how to keep it straight when the "speed brakes" were applied so I turned the nosewheel into a free-castering unit instead.

It's an absolute blast to fly - go for it and hang on tight for the ride.

Flyboy Dave

My Feedback: (21)

Ernie....I looked at mine, and I don't know what the heck it is !! [X(]

I'm a big help, huh ?

buzzingb

My Feedback: (2)

The engine, Tower 75 will run great if properly broken in and the needles are adjusted. I run the tower plug and it seems to run great. It did have the rich midrange on breakin as it should to give everything a chance to get set and fit. Now it throttles up great with no hesitation at all, after I kept leaning it each time at the field. Like all good engines don't rush it and it will respond. The thing is noticably more powerful than an OS 61. Some complain about the muffler coming loose but a little JB Weld on ever joint will take of that. The prop I am running now is 12.5X6 but it will pull a 13X6 ok. I am thinking of a 10X10 on the shrike and if it seems too much I will trim a little off the tips until it is happy.

Razor-RCU

My Feedback: (50)

Sorry I was having internet trouble when I posted the "test" post.

The TH-75 is pretty big for the Shrike, it will work with mods but there are a number of options I would exhaust before using the Tower... Do you have one on hand is that why your gonna use it?

I love my Tower-75 but I would not put one on a Shrike...

Cyclic Hardover

My Feedback: (3)

.The Shrike 40 is already nose heavy enough on a common 46. Frankly I don't think your going to see to much of a difference in rpms and speed but you will have weight issues. I get 120 mph on mine with a simple 46pro and a 9/7 apc prop and I am at 5000ft. My elevator travel goes from horizontal to straight up and I use every bit of it on landings. Nevermine that 1/4 1/2 have inch travel stuff.
Its a handful even with a simple setup as this.

buzzingb

My Feedback: (2)

The Shrike balances well with the Tower 75 and no lead added. I installed APC 10X10 but the 75 needs a 11X10 to hold the rpms down. Will be flying this plane this fall but am not i a hurry.

Rcpilot

My Feedback: (78)

The midrange burble is just not being tuned perfect yet. The low speed is not touchy or hard to tune, but it takes a bit of tweaking to get it dialed in.

I don't usually tweak them for perfection untill I have about 1/2 gallon though the motor. On these motors, I break them in screaming WFO with a little prop that will allow them to run up around 15,000RPM and still a bit on the rich side. Not 4-stroking--just a good rich 2-stroke to keep it well lubed. I keep leaning a couple clicks per tank--sometimes as much as 5 or 6 clicks on a tank and let it scream bloody murder. Then start slapping bigger props on it as it pickes up RPM and gains power. Lean a few clicks and let her scream. Don't even think of touching the low speed untill your done with the high speed break in. Low speed running doesn't do a darn thing for break in except cool it down when you throttle back. I run up to max RPM and let it scream for about 2 or 3 minutes and then back it down to a rich idle for about 30--45 seconds. Then run it back up to WFO and let her rip again for another 3 minutes. Lean slow. Use progressively bigger props and keep it screaming and keep it rich. I eventually end up with a Pro Zinger 13-5 for my 3D planes and they are taching up in the 12,000RPM range.

When you got at least 1/2 gallon through it--then tune the low end for a decent idle and go fly it. I still leave my low end a tad rich untill I put a gallon through it. Maybe 1/4 turn rich on the low end. Lean the low end just a bit every flight.

Eventually, you'll hit the sweet spot right around 1 gallon and it will not burble anymore. It will hold an idle like a Swiss watch and transition well --even after an extended idle of 45 seconds or more. Mine just tick over and idle perfect. Roll on throttle and they snap right up. No coughing or farting. Just smooth transition all the way up to max power.

I've actually done it both ways. The slow method where I lean the low end over the course of a gallon. And also the quikie method where I lean it out after about 2 tanks and never touch the low end again. These engines will transition VERY WELL if you just tweak them in.

RC-Bearings

My Feedback: (1)

I think you would be much happier with a light weight, powerful engine such as a Webra 50. It weighs a full pound less and will spin a very useful prop at some amazing speeds. Less weight, less drag.

skiman762

I think you need a new scale a Tower 75 only weighs 23 oz with the muffler I can't see how a Webra 50 can only weigh 7 oz.

asmund

I`m going to order some of those webra`s for my 15 size planes

RC-Bearings

My Feedback: (1)

I stand corrected. The last larger Tower engines I weighed were the rebadged GMS versions and they were 30 ounces. I see that the GMS has even cut the weight down a little from there.

buzzingb

My Feedback: (2)

Ok here is a flight report,finally for the Shrike with Tower 75 on front. The plane balanced out wihout any lead added with battery in tail and remove about an inch of firewall. Shrike took off extremely well with not too much torque steer to the airplane at all, with a 10X10 prop. Big problem in the air, the ailerons fluttered big time when given throttle over 1/2. It was moving along pretty well for 1/2 throttle though. I was aware of the flutter issue with the shrike and should have changed thing us, but will have to rework the ailerons to prevent this. I am thinking of taking off the last 2 inches or so and maybe the firs inch or os by the fuse. Shrike landed like a trainer as it slid in on the grass. I don't think it is going to fly very fast though even though I didn't get to open it up, I could tell it just wasn't going be that fast.

buzzingb

My Feedback: (2)

It is stange to me that there aren't any fast engines in the 90 size glow. I considered a 90 ST, OS 91, Tower 75 for the Shrike and none rev high enough for a plane like this. I finally went with the 75 because of price. Don't get me wrong here, the 75 runs as good as any and has plenty of power for sport flying. It is just that no engine in this size will open up and rev up to the 15+ thousand range like the 46 engines do. Have any of you installed a tuned pipe on the 75 if so please give us a report?

Flyboy Dave

My Feedback: (21)

Put an 11-7 1/2 MAS prop on it. It should turn 14K or so on 15%.
I use PowerMaster in mine with extra castor added.

FBD.

asmund

I got my TH 75 to rev to 15000 rpm on the 12.25-3.75, not much speed though

JohnMcGowan

My Feedback: (15)

Flyboy Dave, how quick is your plane pictured and who's plane is that (maker, arf? ) It just looks quick sitting there!! And how does it fly?
Thanks,
John

buzzingb

My Feedback: (2)

I wanted to use a 10x8 on the shrike but didn't have one so used the only prop close I had and it pulled ok but rpms won't get that high judging by the ground rpms. I will give the Shrike a redesign the winter and give it another shot later.

Flyboy Dave

My Feedback: (21)

Try the 11-7 1/2 Master Airscrew before you go back to the drawing board....

....trust me, the right prop makes all the difference in the World. Make sure the prop
spinner and backplate are perfectly balanced to get every rev out of the engine. I am
using Powermaster 15% in the Tower, with 4 ozs extra castor added. The fuel makes all the
difference in the World as well.

FBD.

Flyboy Dave

My Feedback: (21)

JohnMcGowan....

....it is a discontinued Cermark 60 size F-20 Tigershark. They were good planes after you
corrected about a half dozen serious flaws. It chugs around at just over a buck on a good
day, nothing spectacular. If you get them"right", and with a Jett 90L, it will chug at about
a buck twenty straight and level. They fly like a perfect pattern plane, no bad habits.

The plane is larger than it looks.

FBD.