|Wing Area:||37.8sq. dm; 586 Sq. In.|
|Weight:||1700g; 60 oz. 3.75 lbs|
|Transmitter:||Futaba 8JA-8Channel 2.4GHz|
|Battery:||4S Li Po, at least 2450mAh (4S 2200 mAh was used.|
|Motor:||unknown Brushless Pre-installed|
|ESC:||40A ESC Pre-installed|
|Available From:||Tower Hobbies|
The Red Bull organization took a full scale PT-17, resorted and repainted it to add to their collection and quite a collection it is!
Flitework has their own rendition of this PT-17 and it comes in a beautiful package. The wingspan is not too large, it doesn't require high end batteries AND other than using some epoxy, all the parts are there: even the prop!
Other than waiting for the epoxy to cure, this model goes together very quickly and displays a lot of detail. I'm sure this one is going to be a winner.
Assembly Sequence: Landing gear (main); Stabilizers; Lower and Upper wing; Radio; CG.
The first step is assembling the PT-17 is to attach the landing gear to the fuselage. Right away you will find a clear plastic coating (decal film) over the screws as well as over the two portions of the fuselage that have to be removed so the gear can be secured.
I would recommend you remove both pieces, insert the landing gear and fasten down the landing gear at one time. I tried doing only one at a time and had a difficult time fitting the second gear into place. With both hold downs out of the way, the gear slipped in easily. Speaking of the landing gear – wow, they are beautiful and the wheels and tires are VERY scale-like. Even the tail wheel is exceptional!
Next was installing the windscreens and gluing the pilot (“Kurt” of course) in place. In both instances 5 minute epoxy from Pacers was used.
The horizontal stabilizer was supposed to be glued into place in the next step but it was noticed the control horns were white and the stab was blue…so a slight detour as all the horns and backplates were painted with some Testors Dark Blue.
After drying, they were mounted on each elevator half when it was discovered the supplied screws were not long enough to reach through the control horn, elevator, and be secured into the control horn’s base. At first I was going to run over to a hardware store and see if they had some small screws a bit longer than the 10mm screws supplied, then I had a thought (very unusual for me!).
What would a modeler do if there wasn’t a source for these screws and wanted to fly this next weekend? Mail Order? That could take up to a week – so that was rejected. So how about making these screws work! So here is what I did and have to admit something: it worked! The blue covering/painting was removed where the control horn and its base was removed, so now there is foam on both sides of the elevator where the control horn goes. The horn and its base were roughed up with some sandpaper.
Some 5-minute epoxy was mixed with a Popsicle stick and coated both places on the elevator where the horn and base would touch AND after the screws were inserted through the base, some epoxy was spread on the screws. This solved the problem as the screws might not have touched the base but they were close and I’m sure some epoxy seeped into the holes for the 4 screws making an epoxy ‘sandwich’. Like I said, it worked! Will miracles ever cease?
With the two control horns secured, it was back to gluing the horizontal stab to the fuselage. The good news is that there isn’t a way to get this crooked! But epoxy in the tail area is heavy so some 5-minute epoxy was applied thinly to the stab, pressed into position and then removed! Why remove it?
I wanted to see if the epoxy was making contact with the fuselage. Any spots not showing a transfer of glue requires some additional epoxy – again lightly. After placing the stab back on the fuselage a quick peek was taken to see if any glue was oozing out – should be any and there wasn’t.
The same procedure was used on the vertical and everything lined up at a nice 90 degree angle. The control horn was installed before gluing. The tail wheel is part of the vertical and is secured in a plastic “U” shaped holder so it can move with the rudder. Nice scale tail wheel to boot!!!
Little bit of language differences as they do call the elevator the ‘flaps of elevator’ and control horns as “levers’ Nothing to get excited about and they do supply THREE separate manuals, one in English, one in German and the other in French.
The bottom wing next on the list and it fit perfectly – how do I know that? The two bolts that hold the wing in place threaded into their respective nuts without a hint of trouble. Again, the control horns for the ailerons were installed while the wing was free from the fuselage as was the aileron’s push rod. I feel it is easier to work on a part of the airplane as opposed to working on a whole airplane.
Remember those screws for the elevator and rudder being too short? Well for the ailerons two larger screws were used in the front of the control horn and two of the shorter ones on the rear portion – and they were all long enough to reach and go through the control horn’s base. In fact the two larger screws were a bit too long and a file brought them down to size.
Now came the part of assembly that all pilots of biplane hate: putting on the top wing! There are two sets of struts that have to be installed correctly or the biplane will not fly the way it is designed to fly. The first set that touches the fuselage are called the cabane struts.
These reach from the fuselage to the upper wing. If these are not aligned correctly, the top wing isn’t going to ‘fit’ properly and will affect flight performance.
So how did Flitework make certain all the struts would ‘fit’? They cut slots in the fuselage that would easily align the upper wing! All the struts were labeled A – F and their corresponding locations on the wing and/or fuselage were easily identified. The cabane struts were glued into place first followed by the two wing “N” struts. The angle was predetermined so all I had to do was making certain the struts were pushed into place!
The next step (after those struts were dry) was to mount the top wing. For this they wisely advised to use 30-minute epoxy as there would be some shifting around and you sure don’t want to be rushed during this important step.
Again the spot(s) that the struts would touch were removed of paint and the plastic material ‘scratched’ with sandpaper to give the epoxy something to grab upon. The wing was placed on the worktable and epoxy was smeared in the proper locations. The fuselage’s struts also had a light coating of epoxy. Gravity is going to make a mess of things if you are not careful.
By inverting the fuselage, it was gently aligned with the wing and each strut was placed into position. The problem with this is that the fuselage will tilt toward the tail and the struts will come partially out of their position. Now would be the time to wipe up any oozing epoxy from the top wing!
By flipping the aircraft over you now have an opportunity to add weights, clamps, or what have you to make certain the struts are in their correct position and FULLY inserted into the top wing. This sounds worse than it really is but it is important to get this right. The plane was left to cure overnight. Other than that, you are almost done!
The Futaba receiver was connected with the servos at this time and final adjustments to the clevis were made so the flight controls were in neutral. Control throws were set to the recommended amounts as shown in the manual.
The final items to complete the PT-17 were balancing the prop and checking the CG. That prop is sure a beauty! It measures 12” but I have no idea the pitch, so as long as the prop doesn’t break, we will be all set. It took a couple coats of red nail polish on the light blade to bring the prop into balance.
A 4s 2200mAh 30C Electrifly battery was snuggled into the battery box and secured with the already positioned Velcro strap. With the battery weighing 230g (8.2oz) the Stearman balanced at the suggested 7.5cm mark. The instructions indicate the battery should be 250g or more but remember the careful use of epoxy when gluing the tail feathers! Tower Hobbies web site indicates the CG should be 4.6" or (118mm).
The “Ready to Fly” weight came out to exactly 1700g (60 oz)….I’ve never built a plane that came out with ‘even’ numbers…so I weighed it again and got the same results – so there IS a first time for anything.
In checking the wing/stab incidence, it appears to be just about 0 (top wing), -1 degree bottom wing and 0 stabilizer. The reason I say 'just about' is that my Robart's Incidence Meter is getting pretty old, but I believe the numbers are correct.
The first two flights took place on a cloudy, windless day with the temperatures in the mid-60's. First of all the CG was correct, maybe a little nose heavy, but not too much. Two batteries (4s 2200mAh 30C) were used. The flight time of 4 minutes on the first flight resulted in using only 25% of the battery. So the timer on my radio was changed to 6 minutes and a second battery was used. After 2 and a 1/2 minutes I noticed at the full throttle setting, the plane wasn't rising so a quick landing was completed. It turned out one of the Li-Po cells now registered 0.00 volts! Guess that battery isn't going to be used again.
The PT-17 Stearman can fly very well on 4 cells and when given full throttle does have unlimited climb - surely not scale-like (but it's fun!). Most of my flying is done at 1/2 throttle. The ailerons are not overpowering but some expo was needed on both the elevator and aileron. Due to the high drag, quick acceleration isn't possible but a couple of times I found the plane too low, too slow and running out of ideas when full throttle was used, it safely pulled the Red Bull out of trouble.
Take-offs do require some right rudder as you start to really get moving as it wants to veer to the left. Up to that point, it tracks straight ahead. Whereas I like long, dragged out take-offs, I have to be aware of its desire to go where it wants (left) as the faster (on the ground) I go. Once off the ground it likes to fly at a moderate speed as this isn't a pylon racer by any means. For landings the PT-17 will slow down quickly, so as you descend on your approach, keep some (1/4 throttle?) thrust going for you and as you begin to fly level at shoulder height, start reducing throttle and the Stearman will settle into a nice two wheel landing.
At first I needed some expo on the flight surfaces and once that was resolved the Red Bull was happy doing whatever I asked of it. Vertical lines were straight, loops nice a large and rolls a bit slow but graceful. The rudder was effective in hammerhead turns but inverted flight did require a pinch of down elevator to remain flying level. The final location/position of the elevator was about 1/16" down! Which brings me to control surface throws...
The ailerons are in need of some significant control throw - and like the rudder, get as much as you can. The elevator, on the other hand, needs VERY little throw! For high rates on the elevator 3/4" was too responsive for this pilot, so low rates at 1/2" was much better. The ailerons at 1" seemed good with low rates at 3/4" rolls seemed only 'fair'. The most I could get out of the rudder slightly over 3/4" to the right but a solid 1" to the left. The rudder push rod hits the fuselage when using right rudder limiting its movement a bit. Still 3/4" is enough for hammerheads and definitely on landings and takeoffs.
While flying inverted I went "hands off" and the Stearman beings to dive at an approximate 15 degree angle - which indicates a slightly nose heavy condition. Stalls were interesting....climb and chop power while holding full up elevator, and the PT-17 mushes forward once, stays level, starts to mush ahead and then drops its right wing into a gentle spin.
If this plane has a bad habit, it lies in the eyes of the pilot! What I mean by that is because this biplane is relatively small and fast, the Red Bull may (depending on the cloud cover) appear to be right side up and going away from you when it is actually inverted and flying toward you ! For that reason (airplane disorientation) the pilot has to keep reminding him(her)self what maneuver is being attempted and what will be needed to recover or continue. A couple of times when flying toward the sun the now all blue airplane appeared to be turning right, when in fact I was in a left turn. The solution to this situation is to keep the PT-17 Stearman close to you and NOT fly at full throttle all the time!
Not a total newbie and not someone who can't fly consistently but lets the plane fly them. The rationale for this is that the Stearman will go directly where it is pointed with no natural recovery tendencies. Now add to the fact the top wing is held on with epoxy and if a cartwheel landing happens, both wings and fuselage will suffer damage. Repairs would probably be easy, but would the alignment be 'spot on'? I'd say wait until the pilot can fly a fast low winged sport plane well.
I like this bird....it assembled quickly (well as quickly as the glue dries), fits right into my flying style and comes with motor speed control and servos installed....it is a beautiful copy of the full scale bird and well worth considering if you want a unique biplane! Here is a shot of the full-scale version.
|Flitework's PT-17 Stearman "Red Bull" - RCGroups.com (4 min 52 sec)|
The PT-17 "Red Bull" really likes to do spins - tight spins, but it recovers quickly!Last edited by tailskid2; Dec 17, 2014 at 02:40 PM..
Replacing the wheels with larger ,more scale-like ones, should be easy. Does the speed control have a switch-mode BEC circuit? If not, I'd add a separate one or replace with speed control that has at least a 1.5 amp switching BEC and use of four servos with 4S lipo voltage. The prop is pretty, I'd save it for display and use a standard brand prop for flying. You did not report that the model nosed up sharply after takeoff, many bipes do, even with proper CG setup. Best to have slight nose-heaviness and land with some power on like a warbird. Flaired landings require a good feel for model's stall characteristics.
I have always been fascinated by big old airshow Stearmans with large wheel pants, cowl bumps, and red with checker-board and sunburst trim as seen at Cole Bros airshows in the 50's.
My next project is a .40 sized Concept Fleet Model 2 biplane balsa kit conversion. Bipes have a special charm all their own.
Looks like the trailing edge of the right inboard wing was damaged in the pictures? Was this damage in the box? I would call Tower about a replacement wing. Looks cool, I think a non scale different colored accent on the bottom of the wing would be good for orientation issues.
I'm not new at this I have something over 30 flyable planes, with that said I managed to totally destroy the Red Bull Stearman on it's maiden flight. First time I have ever destoyed a plane attempting to fly, it was the most spectacular crash I ever saw live. How, why? you might ask. To start off, my part of the blame was to not believe what the CG stand was telling me. As per instruction and the review posted here, I used a 4s 2200 battery that weighed 15g more than the recommended 250g battery. Fits nicely in the battery box and pushed all the way forward, better to be nose heavy in the first flight right? Got everything set up and as usual inverted the bi-plane to check CG. Way too tail heavy at the instructions 75-80mm, let's try the Tower reccomended 118mm? Still not right, let's find out where it does balance with this setup. Not really anywhere comfortably with that wide 75-118mm range. Back to 75mm, what kind of weight do I need to balance there - over 2oz, really? That's what the equipment says. Can't be right, instructions seem pretty confident about a 250g battery, reviewer agreed, I must be doing doing something wrong, CG machine screwed up. Let's go fly it. I have several different PT-17's (bit of a Stearman nut). Ground check OK, take off run, nice and straight and smooth, airborne - disaster CG machine not wrong seriously tail heavy out of control climb and falling off to left, flipping back over head to back of flight line to parking lot, into the one tree around, a large old Oak. Enters tree branches 2/3 the way up, top wing ripped off, immediately flutters to the ground like a big blue leaf. The front, from the wheels forward makes it through the other side of the branches and comes to ground, prop intact. The rest of the plane is scattered between, half of the bottom wing is stuck in the tree branches, the tail section has come to ground under the tree near the trunk, the other half of the bottom wing nearby. The cockpit stuck on a lower branch, ESC is MIA, battery near the motor. Total distruction in about 15 seconds. My part of the blame - not believing the CG machine, Fliteworks, what's up with that mess? What a serious waste, the only thing good about this plane were the wheels and decals. The best Stearman I have is still the FMS version.
Thought I would post a pic of the poor Stearman after it went through the Oak. These are the parts I found and could get to.
An addendum to my previous post to those that want to give this bird a go. The ailerons are very long extending almost the full length of the bottom wing. They seem to be somewhat flimsy, it was my intention to strengthen them with some CF strips after the maiden flight. Also the nose of the plane is very strong evidenced by the non damage in the crash, however there is absolutely no air flow to the battery or ESC. I cut out the panels between the vacuform "motor" to let air in. It is no simple task since there is a stout inner cowling made of thick clear plastic that must also be cut through. This requires removal of the cowling. Good luck.
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