Hello all I am kind of new to RCU at least at posting. I would like some opinions on what some of you consider a underpowered plane. Here is where I am coming from. I will be building a 37% scale Pitts Challenger to look like Sean Tuckers' over the winter. I want to put a G-62 on it and the finished weight should be about 30lbs. I would like it to fly like his plane. I mean if you made a video of it flying and someone watched it with no sound they wouldn't be able to tell if it was a real plane or not. So many people want a positive thrust to weight ratio today, but I have yet to see a full scale plane hover with it's rudder in the grass and then accelerate straight up.
I have read alot of posts here where someone new to rc has asked if a certain engine would be big enough for the plane they are building and people jump all over them and say they should move up a size if they want to do aerobatics.
To me underpowered is:
1. You can barely see the plane when it is time to rotate.
2. You need at least 3/4 throttle to stay in the air.
3. Your vertical performance is directly related to how long you dove at the ground and if your wings stayed on when you pulled the 50 G's at he bottom[X(].
Please give me your thoughts. Thanks.

You pretty much describe my thoughts of underpowered.

There is one Full Scale Pitts Python out there that is actually better than 1:1 on power. I cannot find the link but when I do I'll post it. Amazing stuff

My first thoght is that a G62 flying a 30 Lb plane will be woefully underpowered.

You will need a loong runway for takeoff to build enough airspeed.
It will probably be very tailheavy, don't fly tailheavy. remember Nose heavy airplanes fly terible but tailheavy airplanes fly ONCE!!!

MR G

Why you would want a plane that can only fly scale at best is beyond me. With a G62 you are going to need full throttle to keep the plane aloft. a 30 pound plane is 100 cc size which swings a 27 inch prop. a G 62 swings 23 inch prop. Get a bigger engine. you will need less nose weight and you can always use the little stick on the left called the throttleto make it fly scale.

Kinda funny to read these responses. Warbird flyers fly 30# Warbirds with less wing area, and higher wing loadings, all the time. We don't have to fly at full throttle and we don't need an extra long runway.
I don't think it will be "grossly" underpowered, however, you will need more for most any aerobatics.

I agree with TLH101. It's in what you want to do with the plane.

With the Python example posted at the beginning, the 62 would fly it, and do it generally scale by managing energy. Unfortunately many fail to recoginze that a biplane uses up a lot of available power just in overcoming drag, which is where the 62 and a 37% Pitts would run into each other head to head. As the speed increases so does the amount of drag, sucking up even more power. After the drag issues are out of the way the engine has to have enough oomph to overcome weight and be able to climb. Aerobatics would be performed after the climb has been done and a shallow dive initiated to develop excess speed and energy to complete the maneuver. Connected maneuvers requiring any uplines would take some serious planning and energy management. Long vertical lines and giant loops would be out of the question with an engine that's marginal in size for the plane.


To fly it like the Tucker aircraft would require quite a bit more power though.

Hi Pat,

I was actually talking about a full scale version but I was wrong, it's a Toucan that is turbine powered (I found the links) and looks to be based off of a Pitts Python

http://www.turbinetoucan.com/aircraft/

Better than one to one power to weight. there are videos on this site, just start here

http://www.turbinetoucan.com/mmedia/video.php

Novel thought, what does the designer of the plan say for engine?

I think underpowered is that you can't pull the firewall off at full power. LOL you can always use the throttle to slow it down, but not enough power is asking for trouble in the end, when you need it its nice to be able to pull out of a situation. IMO

Mike

I'm willing to bet that the designer/manufacturer is calling for a minimum of 75-80cc. Typically the manufacturers list the smallest engine thay feel that will fly the model, with performance coming from the upper end of the listed sizes.

That Toucan is in a class all by itself

1.5 thrust/weight ratio is underpowered for me
Good luck!

The G-62 is a good engine for the GP 33% pitts ARF and it comes in at 20lbs or less. At 30 lbs., you are going to need more engne for your project IMO.

Building an anemic aerobat is the biggest sin in RC today.

I don't get what the big deal is on the Turbine Toucan??? Wayne Handley did all the same stuff 10 years ago in the Turbo Raven, and did it with a better looking plane with much less weight and drag than a biplane. [sm=confused.gif]

Oracle Turbo Raven

An aerobatic airplane with a positive thrust-to-weight ratio was a dream come true for airshow performer Wayne Handley. In 1998, he turned that dream into a goal and succeeded in producing a one-of-a-kind show plane. With a 750 HP turboprop engine producing 2,800 pounds of thrust, the Oracle Turbo Raven was able to go straight up, stop, and go straight up again. The Turbo Raven was truly state of the art. Its airframe was made entirely of composite material. The optimization of performance was the design goal in every construction decision while making the Turbo Raven as strong and as light as possible. One result of this goal was a single seat.

The engine was a Pratt & Whitney PT6A-25C which is used in some military training aircraft that require the use of an inverted oil system. The Turbo Raven had a roll rate of 450 degrees per second and a top speed of 260 knots (300 MPH) at sea level. The airplane was IFR equipped, had bleed air heat to the cockpit and oxygen, so flying coast to coast in one day was possible.

The Oracle Turbo Raven established itself as the fastest climbing propeller driven airplane in the world. On January 20, 1999, Wayne took the Turbo Raven from brake release to 3,000 meters (9,842.5 feet) in one minute and nine seconds. This was deemed as one of the most significant world records of the year by the National Aeronautic Association. Later that year, during Airventure 99 at Oshkosh, WI., Wayne and the Oracle Turbo Raven shattered the time-to-climb record to 6,000 meters with a time of three minutes and six seconds. Along with the vertical stops and starts, Wayne enjoyed its ability to fly out of an upright flat spin to the left without lowering the nose below the horizon. He would add power until the nose was 15 degrees above the horizon, then come in with right rudder, add more power and fly out of the spin. The pilot's ability to select reverse propeller pitch in flight was another unique feature of the Turbo Raven. Reversing pitch turned the propeller into a big speed brake, enabling the pilot to make extremely steep approaches. Of course, this feature also allowed Wayne to back in and out of his parking spot - the envy of every other airshow performer.

Missing is the part where an engine part failed and he couldn't pull completely out of a maneuver in time, leaving him permanantly about 3" shorter in height than when he started. There were quite a few aerobatic maneuvers that require instant thrust from the propeller that were not done with the Raven due to the inherent lag time built into a turbo prop engine. Definately not a 3D machine as we would call one today. It went pretty quick in the up and the level, but was not then or now the end all of aerobatic aircraft. Great design, but it had it's own limitations, as will the Toucan. If you ever watched a performance with Mr. handley and the raven that was done with other aerobatic aircraft the differences in the routines was readily apparent.

RCdude,

A G-62 in the 33% Pitts would make it a lead sled. I had one with a much lighter 3.2 in it and it was a flying brick. At anything over 14 pounds it wasn't worth the effort of assembly at the field. 16-20 pounds would have been a flying disaster waiting to pull the sheet metal screws holding the wing cabanes on out of the fuselage. A much better GP product for a biplane is the Ultimate with a 3.2 or under. Great machine for aerobatics and a whole lotta fun.

Well I am glad to see so many people weighing in on this. Like I expected the opinions range from it would fly scale to take a wheelbarrow along. The manufacturer,

http://www.eurekaaircraft.com/airpla...llenger-II.htm

reccomends 4.4cu and up. In emails to him though he has stated flying one of these with a G-62 and it was right about scale. If you guys haven't checked out Tuckers' web site you should. The video there is really good and you can change views from inside the plane to out.

http://www.oracle.com/cluboracle/teamoracle/index.html

During his torque roll he is at full power and sliding backwards. It is almost impossible to know how close he is to 1:1. I emailed him before to check if his color scheme will be the same next year and he got back to me the next day. He said he never knows for sure if Oracle will reup untill the new year. I wounder how much he would actually tell about the plane? I could try.

I have an Ultimate that's a little over 37% and is powered by a ZDZ 120. Weight is pretty close to 30lbs with full tanks of smoke and gas. Both are 40 ounce tanks. Unlimited vertical and hovers at half throttle. I would at least use a ZDZ 80, DA 85, or a 3W85. Good luck.

I think this is what your thinking of

Wayne flew the Oracle Turbo Raven in its first airshow on Oct. 3, 1998 and its last show on Oct. 3, 1999. During a steep approach to landing, the engine flamed out as Wayne was bringing the propeller out of reverse and he was unable to attain the speed necessary to flare for landing.

I just watched the vid it makes my back hurt just hearing the splat ouch..

http://video.google.com/videoplay?do...51820902328022

I've seen the crash many times, but never saw the manuever completed.

He was just do a steep 70 degree approch to landing with the prop reversed and had a flame out
it's on this vid here with out a crash

http://video.google.com/videoplay?do...92639009239481

Well, I have see Sean Tucker fly his Challenger first hand (this summer again at the Cleveland air show), and if you want your plane to fly like his full scale Pitts, your going to need at least 80cc for that 30+lbs. That 3.7ci just ain't gone-na get-er-done. Fly..........maybe, but not without a lot of dead weight up front for ballast, and you will be on the verge of disaster, with the look of a heli pilot on you face[], most of the time, IMO.

Having said all that, I for one, am looking forward to the construction pictures you will surely post. What a great subject to model in that size. Miles Reed (I enjoy being in the same club with him and watching him fly his 40% Weeks Solution all the time) built two last winter in Sean's colors in 40% scale, for Sean's sponcer. Awesome big bipe.

Thanks for all the advice. I will probably go with an 80 to 85cc. Kit won't be here for a week or 2 so I have plenty of time to get an engine. I will start a new post so it will be visable out front when I start. I will need more advice along the way, this is my first giant scale plane.

Who's kit is this?

I ordered it from
http://www.eurekaaircraft.com/airpla...llenger-II.htm
I talked with Dave Dessecker ( the guy that has the rights to Miles Reed's plans)(Miles Reed is the guy that designed Tuckers plane) They offer builders kits of this plane only and with this being my first large scale build I would rather have the pieces pre cut.
Dave Dessecker actually has three different size plans for this plane a 69 1/2 in a 85 3/4 and the plans for the ones Miles built the huge 93 1/8. He also sells plans and kits for other planes a couple Weeks solutions, Extras ect. Dessecker dosen't have a web site but I have his paper with his planes and prices I could email you if you want to see it.