Yea, I've been sidetracked a bit with the .90 on a .40 plane but I'm liking it! I agree, it won't fly as intended but that is pretty much the point. My .19-.25 sized little stick with a G-51 and pipe/header flies nothing like a Little Stick did in the 70s and it still lands at a crawl. Besides, the Ultra Stick has flaps! I let another guy at the field fly my little stick and he said he has to have one. Only the purists don't seem to "get it". Don't knock it until you've tried it!

The Rolls-Royce combo sounds wicked by the way! Have no idea what it is but it sounds wicked!

Jay Leno has a Merlin V12 in an old Standley Steamer. There is excess everywhere!!!!!! If I had the money, none of my cars would have the stock motor in them. They would all be filled with excessive motors. Too much is just right!


I once saw a Suzuki Samurai at the drag strip with a 632ci big block Chevy in it. It was cool!

One last comment. If you just have to fly a Super Tigre .90, look around on the various auction sites for a NIBST .90K. It has a two piece block instead of the one piece block of the G90, which is a fine engine itself. The thing is, the S.90K is more powerful than the G90. Why Super Tigre would bring out the G90 to replace the S90K, which produces more power, is a mystery to me. Of course, they went out of business a short time later, so it may have been the same logic involved.


Ed Cregger

Spinner,


The Rolls-Royce combo is what is now installed on the wings of the Lockheed C-130J, Alenia C-17J Spartan, Saab 2000, Bombardier Q400 and a few others...

This 4,591 HP engine spins a 13.5 ft. diameter, 6-blade prop...


Having a lot of power, on the same weight, is nice!

Having even more power and more weight, to me is too much.
There is a limit to the amount of power; and it is the amount you can actually use effectively.

Adding weight spoils the whole point.

EDIT: Corrected size of prop.

My kind of engine!!!

We may have to agree to disagree on this one but I'm only going to be adding six to eight ounces and if I have to put the battery in the tail (like I did with my little stick) to keep from adding weight Iwill. Adding half a pound and almost doubling the horsepower and picking up about 4lbs of thrust is something that I can deal with! Perfect combo for fun Went shopping for planes at lunch. Got another LHS to hit on the way home so that I can get this project started!

The plane will have a throttle by the way. My other plane flies "spiritedly" on half throttle and WOT is used almost exclusively for vertical stuff.

<div style="margin: 0in 0in 0pt"><span style="font-size: 9pt">IMHO...if you want a plane that is stupid crazy fast including vertical, then buy a plane that is designed to fly that way. There are a number of designs that will fly extremely fast with a 55AX designed for that power and speed.

My concern with putting an oversized engine in a plane not designed to fly as such is a risk most "shouldn't" be willing to take. Flutter is nasty and can cause a situation that you no longer have control of the plane. If this happens near people...dangerous and life threatening things happen as a result...Drag is the equalizer...If you exceed the threshold, she will break up Scotty!!!!

I'm ok with putting a 55AX in a 40 size sport plane if you beef it up a bit and manage the throttle. I would say this is like putting a 289 in a Pinto...Fun, quick, and a lot of show...

Putting a 60 or larger in a 40 size plane is like putting a 428 CJ in a Pinto...Something is going to break at the wrong time...You can't beef it up enough for the power...Drag and Power collide and bad things happen. Now put that formula in the air and a disaster is around the corner.

My .02

Larry Diamond</span></div>

Well I don't think spinner is worried about the fact that it won’t fly as intended or be as graceful. He's tasted brute force power and now he's addicted. There's just no saving him. LOL.

The OS55 w/stock muffler will have plenty of power in the Ultra Stick 40 for unlimited vertical and it will "harrier in"(float) in flaps& crow mode with that engine. Even with this engine you could pull off or flutter the large control surfaces in full power level flight with it propped for speed so watch your speed especially in a dive.

I totally understand spinner's desire for more power because its just plain funny to see a plane go strait up like a freight train or instant power to yank it around. I do put the biggest engines and fuel tanks that I can cram in to my some of my 40 size planes but it comes with a cost. Count on extra strength mods, time to do it, better servos and hotter landings.

Ultra Stick 40 has short landing gear so a 13" or 12.75 diameter prop may not last long. I ended up running a 3 blade with a Saito 82 and a OS 55, I don't remember the sizes of props I used. I cut a hatch under the tail for the batteries so I didn't need to add weight to the tail (you may not need to do this if you loose the heavy junk aluminum engine mount that comes with the kit and use a glass filled plastic mount). CA coat the wing mounting dowels so you don't get wood to wood rubbing, mine started burning from the friction!

You could put an OS 91 FX in it but you would have to be extra careful with speed and landings. The fuel tank space is limited.

Note that the OS 61 is actually heavier than the 91!

Spinner,


Let us examine this from the horse-power perspective...

How much more output (HP/kW) do you think are needed, to go twice as fast?...

Let us see; drag must be overcome and it grows by the square of speed... I.e. overcoming drag, while going twice as fast, requires 4 times as much thrust...
Had it been a jet engine, or a rocket motor; rated in lbs thrust, it would be all you need.

But no; this is an engine driving a prop, which must apply this quadruple force...
At twice the speed; this force must be applied at twice the rate per time unit...

So, going twice as fast absorbs (and requires) no less than eight (8) times the horsepower.

Twice the HP would make the same plane (with the same drag) go faster, by the cube root of 2; i.e. only 26% faster. That is all!


So, your notion of having double the HP, no longer looks as appealing to you as it did; does it?

Going 1/4th faster than before is visually noticeable, but is not as easy to see as going twice as fast.
Double the static thrust would double the static acceleration of the same weight, however.


I am not sure flying a model, with a prop as large as the wing-span, would be very appealing... 'Appalling' may be a more descriptive term...[]


'Too much POOOWWWAAAH' is to me, a profanity...

I don't want fast, I want POOWWWAAAAHHH! I plan to put a 3D prop on it for the most part (if I can get the landing gear tall enough). A 91 with a pipe turning a 13x6 will be stupid fast at WOT on a .40 Ultra Stick but a 14x4W would slow it down on straight lines and landings. I talked with one of the board members that flew this combo for several years last night (Ultra Stick 40 with an OS 91 on it) and he flew his like I would fly mine. 1/3 to 1/2 throttle horsing around / take off and WOT on verticle lines. He used his for climb and glide competitions and general fun flying. I'm not going to go pylon racing with this thing as the control surfaces are too big and I would be worried about flutter as well. He had some good advice for wear issues that I need to look out for and some areas to re-enforce. So guys, I'm not doing anything new here - I'm not that smart - obviously!! Keep the suggestions, comments, criticisms and snide remarks coming! It's all good.

Another suggestion was a Magnum 91 as an inexpensive alternative to the Super TIgre I was planning on using. I hear they are lighter as well. I'm having a hard time finding someone that sells an XLS 91. Anyone have a suggestion where I could look for one?

Thanks!

Spinner,


A 13x6, or a 14x4W prop, on a normal, muffler equipped .91, is below the optimal load.

The engine would be 'over the hill', as far as its HP curve is concerned...
The engine would be spinning at higher RPM, but actual power output would be diminished.

The engines would spin beyond the RPM, where the engine makes its greatest output.

If you go to the Jett site and examine [link=http://www.jettengineering.com/engines/bse40.html]the BSE .76L[/link], you'll see it usually comes with a non-tuned muffler.
It is set to spin this prop at a rather low RPM of 10,500.

The OS.91FX/ST .91G, are not nearly as 'plugged up' as that Jett, so they are capable of spinning 13-14K effectively, with a normal muffler, or without any muffler.
But ultimate power would be achieved, with a tuned exhaust system, on a larger prop, spinning much more slowly.

If you check out the results in the [link=http://www.supertigre.com/engines/supg0235-man.html]ST .91 review[/link], you'll see the best pipe could only get maximum power equal to the open-exhaust number, proving induction does not permit the engine to make any more power.

The OS is maxed-out with a JettStream or UltraThrust, both high RPM tuned mufflers, spinning a 12x10 prop (roughly equal in load to a 13x8).

Both engines are limited by their induction, having a large displacement crammed into a rather small frame.

So you (and from the looks of the article you linked) are saying tune with a larger prop to keep the RPMs lower to keep them in their torque curve. How about an APC 14x6 I wonder? I may have to make my own landing gear for that one. Have to watch torque rolling on takeoff as well with throttle management!

I ran a 14~8 APC on my S90K with a Magic Muffler at 10,000 or so rpm. Pulled an (8.2 pounds dry) Joss Stik with authority. Including straight up.

Terry in LP

edit for adding: Yeah. I built my own landing gear as part of the weight saving effort. Made it out of piano wire front and rear pieces wrapped and soldered together just above the 'axle bend'. Came out quite a bit lighter than the stock f/g gear. Taller too.

I ran an apc 14x4 Wide blade prop on a super tiger g90 and loved the combo. The plane was a 60sized chipmunk and it was way overpowered and fun to fly. That prop does spin up, but the ST really liked it.

On a .40 sized plane I think it would be a fantastic combo.

As to the 225 servos, although their torque numbers are impressive, their gear train is light. They work ok on speed planes with very little surface movement, but on something like a stick with big ailerons and elevators, not sure they would hold up well. Probably would recommend at least standard sized servos here.

Thanks for the reply! Hoping to hear something like this. Yea, I've about talked myself out of the HS225 servos after hearing more than one person steer me away from them. I have a few of their HS5485-HB that I will probably use instead.

I've been advised to look at the Magnum 91 XLS in addition to the Super Tigre. Don't seem to be too many people that sell those. Looks like it has the OS 91 bolt pattern for the exhaust which would make finding headers and mufflers pretty easy.

I'd suggest running the motor as is before setting up the pipe. It may have enough POOOOOWWWAAAAAAH that you may not even bother

My ST is the newer Chinease one and it is one of the best running motors out of the box I have ever owned, and I've had plenty of the expensive ones including Jetts and Nelsons.

Oh, the 90 with the stock muffler will be more than enough I'm sure. But... This is going to sound real stupid, but I can't stand the way Super Tigre mufflers sound. I love the way a pipe sounds. The Super TIgre muffler is a bit heavy as well. I have two Super Tigres and neither use the stock muffler. So I plan to put a pipe on it for the sound more than anything else. Believe it or not a pipe and header weigh close to what the stock muffler does. I might even try to get an ESComposites carbon fber pipe for it. One of my goals is to try to get this plane to weigh with a 90 what it would weigh with a 40 sized engine and stock muffler. The first thing to go will be the Ultra Stick's aluminum engine mount (I was going to need a different one any way), and anything else I can do to lighten it up. I may use a water bottle for a fuel tank (done it several times in the past) and that saves some weight on the nose because water bottles weigh next to nothing (I used one in my Little Stick for instance). Right at or under 6lbs and this thing will be sick! Careful servo selection and I may use an 1100mah A123 battery which would weigh half of what a 5 cell AAsized 6v pack would weigh. I may buy the plane this weekend and after I get all of the parts I'll start a build thread in the ARF forum so that those guys can laugh at me as well! I've been asked in PMs how old I am. I'll be 47 in a couple of months.

Thanks for the reply!

The mini servos are light and work great for throttles. Also, the Dubro Feather Lite tires save a *lot* of weight. If you have excess axle material sticking out, cut as much as you can off with a cutoff wheel. You would be surprised just how much weight that is when you put the removed pieces in your palm. Foam wheels for small electrics work great for tail wheels instead of the heavy rubber/plastic ones.

I have the feather light tires on my Little Stick and you are right, they are very light even the three inchers I'm using (grass field and BIG prop). I still might put the Hitech Might Mini servos (HS225-MG) on the ailerons and flaps. If I forgo doing the flaps then I wouldn't use the minis but four servos on the wing should spread the load out enough but Imay be wrong.

Well, it looks like this project is on hold for a while. Mother nature paid my home a visit last night and pushed a 200 year old oak tree down on top of it. I have lots of skylights now - some big some small. Nobody was hurt but I won't soon forget the sound it made coming down (almost as frightening as a 91 on a pipe I'm guessing). I'm in the Dallas area and lots of trees, signs and fences were blown over in my area with the big storms this morning.

I'm down for now but not out. I'll be back causing trouble in no time!

You and yours are in our prayers. Hang in there.


Ed Cregger