It would cost $50.00 blown up to 160"

And it's $40.00 to ship to Malta. Package weight is going to be about 2 1/2 - 3 pounds!

You can get my mailing address off the web site at: www.cmsmithplans.com

Do you have any info on cost for the kit? Really interested.

Thanks,

Jimmy

The U-2 is now produced by PAF models in Germany [/link] :http://www.paf-shop.de/
He also sells tanks and pipe as well.

Hi Mike,
It's been ages, but I never really had much time to get the U-2 Done, but It looks set to fly in two weeks time. Weight wise, after finishing and adding all the servos the weight is up quite bit. I need to do some final spraying, which will hopefully create a panel look. I haven't weighed it yet but, it definitely close to 20lbs. I agree I need a long runway that's why it's going to happen on a full size runway. I think if it flies well on the BVM 96, I will definitely put an Electric DF in it. I think Acceleration will be a little slow initially, it's running a BVM T-33 Tail pipe set up. This Motor did well to fly a 22lb BVM T-33. I included some pic's I took yesterday, It's good to be almost complete. Pogo's have been finished last night, Canopy will be done tonight, then it's Balancing and running the engine...

I just noticed this thread originally started in 2002!, i would like to know if Werner Kranz is still in business or not. Last i was told that he went out of business many years ago but it would be great to know if he is still around. I have his B727-200 kit that i may build it or sell it i don't know yet. His U-2 would be another interesting project.

Any updates, Sean, on flying the U2?

Hi there,
Yes, the U-2 Flew for a few brief moments, lifting off by itself, however it had a serious lack of power! I took off in a slight cross wind, and as soon as the wheels left the deck it started to drift to the right, the problem was with such a high aspect ratio wing as soon as you use the ailerons with not enough speed, well the wing will stall. The rudder was totally ineffective at take off speed, so I couldn't really correct to many spectators in the way, needless to say I broke the nose clean off, when the wing stalled, I have repaired it already, and will test fly it as a slope soarer at the end of November, after that I will upgrade to a 12kg turbine (more then enough power). I will post some picks tomorrow at work
cheers for now Sean

Glad your damage was apparently semi-minor! At least no broken wing. I've got one I've been building for years-can't seem to get aound to finishing mainly 'cause I can't decide how to power it. I understand the relative problems with that type of craft.....broke a few gliders like that. Years ago, used to watch the full sized guys do 'touch and goes' with the U2 when I was at Patrick AFB in Florida, always been one of my favorite planes. The turbine should do the trick. I built a Schreckling way back to go in mine but never could get it to run properly. I'm now moving into the EDF arena. Look forward to the pics and hopefully good reports of successful slope flights.

First flight: check
crosswind: check +
spectators: check +
===
crash: check

Ya gotta wait for perfect conditions with a bird like this. Once you get the controls dialed in and comfortable you could be less strict about conditions. Not trying to put you down or embarass you here, just something to learn from. Others who have tried the U-2 have been bitten by the cross wind and tip stall. Most that I've seen, actually. Much like a scale sailplane, you get too slow and you'll have no control. Things to keep in mind; ; some flaps will help avoid tip stall, some reflex in the ailerons will too. At least 2:1 or 3:1 differential in the ailerons is needed. More travel in the rudder than looks natural. My personal preference with sailplanes, scale or not, is to put a aileron/rudder mix on the landing mode/landing gear switch so you always get rudder mix when close to the ground.

wsmalley, I had been intending to use a turbine in mine, but having left it this long am now considering going the e-power route too. We ought to compare notes. I'm thinking about doing a homebrew conversion of a ram-tech or dynamax fan, since I've got them in a box somewhere and some good, affordable motors are coming out. Shouldn't need too much power/thrust. Should be able to get 10-12 lb thrust out af a conversion - which ought to be plenty for my plane around 20-22 lbs.

I second JOHNG's remarks. The U-2 is no crosswind airplane. Mine is built from the Kranz kit and I only have a couple flights thus far due to the trade winds in Hawaii (12-18 knots most days). The first fight was harry due to aft CG. The second was much better. Flew like a big trainer until landing the bird gets pitch sensitive when you lower the flaps. A no flap landing sure eats up the runway and you have to stall the thing six inches off the ground. Still sorting that out.

Mike, your bird sure looks nice, especially the nose down attitude on the landing approach!
Paul

Thanks Paul!

I don't know about the semi-minor Damage, there are many stress fractures on the Airframe being Fully Built, but it's nothing that CA can't fix. The One wing has quite a bad crack [&o]in it but none of the main Spars are damaged, But once again it should be easy to fix. You can see this in the one Photo after the spectacular event had happened. Also I included some pic's after the nose has been rebuilt.

JohnG', I did mention a slight cross wind, it was slight, I backed out of two Maidens the previous day because of gusting winds[8D], when I attempted this it was about 2kph, from the south west, this was a 08H30. The amount of runway used to get airborne was about 180-200meter's, we where using a full Size Taxi way. I did say through it all I will not force the aircraft off the Deck, which I didn't, it did everything by itself and was flying just dandy till the wind, you guessed it started gusting gently. By this time I was 2/3rdsdown the Runway, the Rudder has about 40mm of throw so that should be ample Rudder, and for the size of the Aircraft it should be fine. I'm guessing though with the lack of airspeed it becomes a Titanic and Iceberg in situation Rudder becomes too small and non-effective .

As for spectators, well I guess that's what happens when you arrive at a Fly-in with a totally unique aircraft you have loads of Pilots wanting to see, they where all well behind the spectator line, which was +/-80meters away. This all didn't happen fast there was time for everything, even the cart wheel looked as if it was in Slow motion. I had to force the turn not only because I was halfway to the spectators just to the right of the Taxi way but because of the JET A-1 Tanks and refueling station (For Full Size aircraft) right in-front of my "new Flight Line". Have a look at the one Photo, The White area is the Runway, the Red Area was the Obstacles after drifting, the Yellow area Which I was aiming for during the Drifting which Would have been safe had the Aircraft built up enough Airspeed to prevent stalling the wing. Altitude at this time was about 2.5meters above the deck.

For first Flights on any of my jets, (actually any of my aircraft) I don't Dial in any Dual Rates, with round 45% exponential, the U-2 Has 30mm down and unlimited up Travel on the Ailerons, (Flaps can do about 120 degrees if not limited) so should there have been enough airspeed I could have corrected the drifting to the right, but Knowing that this will stall the wing, I didn't touch it unless I really really had to, unfortunate I really had too. What I should have done was kill the power (or the Lack thereof) and forced it on to the deck. But then hindsight is also an exact Science I think the Aircraft would have flown better into a head wind but, at Oudshoorn the Taxiway, in the all years I have been going there I have yet to see a head wind on the taxi way.

The original Idea was to get it working on the BVM96 (15lbs Thrust +/- using a BVM T-33 Ducting set up) and then put a BVM EVF (Same Set-up 16.5lbs thrust +/- with 7500mah with Saddle Pack) in the aircraft, but at 22lbs with Fuel (The Down side of a 100% built up jet of this size), I wouldn't even put in a EVF now, Don't Risk it, it's not really worth it. I will go for 12kg turbine 120N a Jetcat or ModelMechanic's, 26lbs of thrust would be more then enough. I have seen a few Full sized U-2's fly and on take-off they display an impressive amount of Acceleration, speed and power. Something I think every Model U-2 Should have for Take off.

I think if you scratch build one of these as I have done, and it's not off plan. There is always the "it may or may not fly" attitude, and also considering this is the prototype basically it's got one chance, this bird will live to fly another day. it will make it's Maiden full Flight on a Slope, then will go back to power with a Turbine [8D]

Great looking bird, maybe you could post some pics of your gear/pogos or other details. I always like to learn how others approach building. I think I read the fullsize could only turn at 15 degrees, called it the 'coffin corner', I believe. Imagine a big model will pretty much follow the same parameters. The turbine would be the perfect solution, they've come so far along. I had an old JPX 260P I thought about but it was too big with the fuel tank to try and 'shoehorn' in. John: I'm trying a 4 1/2" fan with a 700kv motor and 100A ESC I got from HobbyCity in Hong Kong. Of course, a Neu or comp would be the best. They have a lot of fans, quite cheap and a pretty big selection of motors, and have some good data on different configurations they've tried. I modified one of the motors with cooling holes, ceramic bearings and JB Weld'ed the windings. I've only run it in a test stand on 33v and easily got 5 1/2 lbs with my 3 little batteries. I just don't have the bucks to put in the eTurbax rig. I have a Turbax/Rossi .81 combo, but hate the sound of those, and think the fans are comparable.

BTW, Sean, did you build washout into your wings? I've got foam cores I had made but don't know they should be setup-that is, washout or no. I don't have plans either, just scratch building.

Hi There,
There is no washout in the wings they are flat on the bottom, a classic Glider airfoil. I'm not sure what it is but it's easy enough to find out. Mine has a 4 meter wing span, and is a TR-2 version, there is more detail to it but it's not 100% complete or scale added. Depending on your scale you could use the Fan you have in mind, just make sure that you batteries are cooled properly because there is not to much space in the Fuz. The Pogo, are made for 5mm spring Steel, with a hole drilled to suit Dubro tail wheels (I will post some pic's) you can drill holes with a tungsten carbide bit in a dremel, then Silver solder them. The Pogo has a washer soldered on with a spring from a 4-40 pushrod, this is to eject the pogo on take of really simple and really effective. The Pogo's holder is also simple to make but take a little bit of care. it's a brass tube to perfectly fit the pogo's spring steel, First Silver solder a small washer at the end then use a wider 3/4inch washer on top of this, this provides a bass, this is then set in a 4x4 inch, 6mm ply block in the wing. That's all there is to it. The pogo's don't fall out that easy when taxiing.

What scale are you building the Aircraft?

Sean,
So your Pogos are a friction fit and eject when the weight is off? What keep the strut from rotating? I used square stock in a square tube, but the pogos keep falling off while taxiing over rough ground. Maybe I need to make my stuts longer to keep weight on them all all times.

Hi Mike,
the Pogos, Do not rotate or wobble at speed, they go in the direction the aircraft is being pulled or pushed this is because of the sweep back angle I made them. The benefit in doing it this was is that the you don't need to have it sprung. I designed it using the principal of the full size, where it can rotate freely, there is no need to lock it in place. There is enough excess on the end of the Pogo to prevent it failing out by accident, it as soon as the wings lift 10 or 15mm the spring will eject the pogo. There is also a slight amount of free play in the Steel / brass tube combination.

The strut doesn't need to only be longer but the sweep back angle need to be more, so it's technically held in place by any forward / lateral movement, this I discovered also by pure accident because I made them to long and cutting them shorter again would have been a pain so I bent them further back. The advantage of this is that is takes hurdles in it's stride, obviously to a point though.

Sean,
Thanks! I made mine from music wire because I couldn't find any spring steel. Yours are nearly identical to what the full size looks like. I reckon I need to find some spring steel!

I'd like to see more from both Sean and I-nav about their flap systems. I-nav's pics look like they have 5 or 6 hinge points - just by the shadow in the hinge gap. Are they slotted flaps or plain?


The plane I bought had the wings skinned by the previous owner. I need to get them on a long flat table, but I don't think they have any washout. I do know they were built with scale airfoils, which is unfortunate. I may build new wings just to make sure everything is as it should be. I couldn't find a data sheet with washout data, but photos on the web look like there's 3-5 deg of washout there.

What did you guys do for retracts & struts?

Don't have anything to add just wanted to move it back to the top of the list.

Hi Mike, 5mm piano Wire will also do the trick, but drill holes in it becomes a little difficult, but Like I say you can do it with a Dremel and a Tungsten Carbide bit. Just get the rev's right and the Bit will reach the right temperature and go through like a hot knife in butter, I can draw up the arrangement in AutoCad if you would like, it shouldn't take too long, but the Pictures show all the information too.

John,
My wing has zero washout, flies well. I put a couple of degrees of reflex in the ailerons. Flaps are plain flaps with the Robart large hinge points set at 45 degrees ___/\_______ so they have a fowler effect. I'm using one 8611 servo but it really could use two for extra stiffness. The each flap is nearly 3 feet span so if the flap isn't stiff you need more servos. Like I said, the airplane gets a little unstabile in pitch when I lower the flaps so I'm going to add nose weight and elevator flap mixing on the next flight. Gear is a Robart 630 in front and an old Spring Air unit in the rear.

Here's the link to the new firm in Germany that's selling the U-2C : [link]http://www.paf-shop.de/[/link] They offer fuel tanks and a pipe as well.

Sean,
Your pictures tell the story. Thanks!

Hi John,
The scale Airfoil should make no difference, My U-2's Horizontal Stabilizer has an invert airfoil much like the original (Just I made an error of having it too thick). The Real U-2 has a NACA 63a409 (which is 9% thickness) and the tip is the NACA63a406 (which is 6%) , this shouldn't relate to any washout, as 3% will effect the slight under camber at the trailing edge only. I went for the easier option and used a Reynolds number airfoil for the speed I was aiming at. This will only affect the Stall Characteristics of the wing, but they are so long anyway, you won't really need to worry about stall with a motor once it's airborne. Tip Stalling, isn't really going to happen it's so long, but as in my case you can stall the wing...

Regarding Flaps, My Flaps use normal 6mm Robart Dowel Hinges at 45 Degrees at the Bottom of the hinge line, this provides a scale, I took pictures of the Full Size at RAF Fairford a few years Back, so 80% of what is on my aircraft is as close to scale as simplicity would allow,being basically a prototype. have look at this pic, [link=http://www.clubhyper.com/reference/u2sfiles/U-2S_DragonLady-63.jpg]Left wing Flap[/link] , the flap is fared on top and bottom with a off centered middle hinge point, with a Perfect Fit. You can do what I did because you won't even notice the extra effort this will take. overall on the wings, I didn't spend much time making it 100% scale, it just has to look the part.

The Biggest Part of Advice I can offer is make the LIGHT, I added 3lbs Lead to the nose which I wasn't counting on and that added to the overall weight from my projected 17lbs... REALLY DEPRESSING.

Retract, I used a SOLID Aluminum F-86 nose gear retract from Trim aircraft [link=http://www.trimair.com.au]Trim Aircraft[/link], it's got very little in the way of steering, but it's super strong and best of all it's thinner then any of the units from BVM, YELLOW, ETC, which I tried, the rear unit is a spring air Retract. The smaller the version of the U-2 the less space, the at 12th Scale the TR2 / U-2R the Fuz is about 20% narrower and smaller, making evening a tight fit.

Hi Mike,
I saw a Video of your aircraft Flying it looks stunning.
I have a quick few questions for you:
What is the wing span?
Does your Model have Foam wings?
Was it from a kit?