I recently bought a Dr1 which was 90% built, and finished it carefully and covered it with Solartex. No drawings came with the model, so I rang Flair to get the CG position which the said was on the mainspar position of the middle wing, which is where it came out without any ballasting. I fitted an independent Rx, battery & switch in the top wing centresection, to avoid running wires down to the fuz. and this works very well (as long as I remember to switch on!) The model looks immaculate, BUT - it just don't fly very well.
Takeoffs are always a bit hairy, and almost impossible in any wind (though that may be just me) and in flight it is unstable and drops the nose quite a lot in turns. When attempting a roll, it gets halfway round then stays inverted and has to be half-looped out to get it back level. All in all, not pleasant flying!
Any advice would be VERY welcome, as I've almost given up on it......
Engine fitted is a Zenoah 23cc.

hi
it sound you are dealing with nose heavy issue.you might want to ckeck your balancing again.also remenber you are flying high drag airplane, i will surgest to make resarch on prop range for your engine.by the way want kind of engine used,prop size?


adetoyinbo

What does it weigh? What prop are you running on it?

My second (and first) Flair 1/4 Dr.1s flew very nicely at 15# and 14# with a Zenoah G-38 on the first and a G-23 on the second. The 23 is plenty of engine for that plane. I'm running an 18-6 prop on mine.

The extra receiver and battery pack added a LOT of weight up high on the airframe. I believe this is one of your problems. I also think it's slightly nose heavy. This plane sometimes needs rudder assistance in turns, especially at slow speeds. As for slow speeds, this plane also has a LOT of drag. Don't get too slow or it will bite you. Even though it's only 72", it still needs a lot of room to recover. Mine is easy to take off, just keep your thumb on the rudder stick and USE IT. Landings are interesting. Don't get too slow on final or it will drop out of the air. Come in at about 1/4 throttle until you're over the threshold and about 2' high, then chop it. Let it settle mains first. Don't try to make 3 point landings with it.


Dr.1

Thanks for the comments[8D] I will re=check the balance and remove the top wing radio gear, and see if that improves matters.

Don't let it get too slow, Kevin. My Dr.1 is at 3/4-full throttle at all times, except on landing. If it's too fast, go to a lower pitch/larger diameter prop.

Dr.1

Dr1's Rule.

Yes but a B*t#h to land, ground handling is different. He wants the plane nose heavy, but not too much. Rolls are interesting on mine. Check all control throws, you could be off on a wing. Use your throttle on landings and be careful when you flair. (No pun intended)

Every Fokker Dr1 hates windy days, and don't ever try to fight a crosswind on takeoffs and landings! One thing I've noticed is my Fokker Dr1 loves to weather vane in any winds over 5mph. Any multiwing aircraft that only has one wing with ailerons has a interesting roll rate, matter in fact it's terrible by most standards, and a Fokker Dr1 more so than most.

But what is really cool is when I kick her in a flat turn! Climbs like a monkey, and turns like it wants to bite its own arse. Doing loops is very good and can be done in a tight fasion. Haven't tried inverted flight yet, but I plan on doing that next year with some altitude from the ground.

I'm still in the process of seeing what my plane can do before I do mock dogfights with it at the big shows.

Here's my maiden flight of my custom rebuilt discontinued GP Fokker DR1, I only flew it once this year because of the weather we've been having up here in upstate NY. It was always windy! What was bad was winds were even gusting when I made the decision to finally fly her. I had my hands full and was glad to get her down in one piece!

[youtube]http://www.youtube.com/watch?v=ASZqoy_uMnc[/youtube]


Pete

The basic handling problem with the DR-1 is excess aileron yaw caused by insufficient vertical tail area, along with its use of only two ailerons. The same problem afflicts many WW1 designs; the Tripe more than most. An enlarged rudder of the same shape would not be all that noticeable, and should give a big boost to handling. I have fixed several evil-handling model bipes by simply enlarging their fins and rudders, but haven't as yet tried this trick on a triplane.

In the end it is a model of a WW1 airplane, and not a very good airplane at that, to model. Won't roll? Neither did the real one. Directionally unstable on the ground? So was the real one. You can cheat by tying the mainwheels to a common axle. Won't xwind? Neither did the real one. All t/o's and landings strictly 'into wind'. In the air it will be a rudder/elevator airplane, the real one went round corners without ailerons, rudder would slip the thing sideways without banking, good combat manoeuver as your opponent didn't get a chance to guess which way you are going to go. But a difficult airplane to fly well. Landing? Where most of the full size got damaged. And you want a simple model to fly? Perhaps a 'Wotbox 40' is more your line? It is what it is, and you need to learn to fly, it has all the vicsitudes of its peers, and few of the qualities. Which makes it a good airplane to learn on before stepping out with the others.
Evan, WB #12.

His already has the enlarged rudder, it is much larger than true scale. The DR 1 actually rolled quite well. And this model should as wll. Not rolling at the top of a loop is from lack of airspeed, just need more power.

My DR1 roll is sloppy, but if I use my rudder in the roll and power out- my roll becomes improved, but not enough for those who are accustomed to a Extra, Yak, Cap, Ultimate or Edge roll preformance. It would be like comparing apples to oranges if we were to do that IMHO. My Immelman Turns I struggle with and need help with the rudder and throttle, and still I'm a little sloppy! But that might be more due to lack of hours on the tripe than actual handling. I have somewhere some documents on the Dr1's handling, but until I find them, please check http://www.fokkerdr1.com/ for more information. The webmaster is very knowledgable and will be eager to assist anyone with any Fokker Dr1 questions.

I read that the original Fokker Dr1 and Fokker DVII had a terrible roll rate compared to the Camel, Pup, SE5a and Spad with the Oberursel engine. The Fokker Dr1 advantage was its maneuverability and climb rate, but it was slow and not pilot friendly. Some pilots used different engines, such as Jacobs, which increased the HP output of the engine, maneuverability and power. The Fokker DVII was faster, but not as maneuverable to the Fokker Dr1 (the old adage - speed = less maneuverability, and vice-versa). But it was a perfect match-up to the SE5a and Spad. When the Fokker DVIIF came out, the Allies had nothing to throw up at it that could match its speed and maneuverability (but there were rumors they were working on something). That's one of the reasons why the Fokker DVIIF was outlawed in the Treaty of Versailles agreement.

The enlarged rudder does help, but that's for the average RC pilot's advantage to be able to fly this RC aircraft. True scale RC Dr1s are extremely difficult, and sometimes when we take an airplane down to a scale that fits in our living room and doesn't tick off the wife by knocking over her Hummel figurines, some of the scale gets, well, out of scale - accuracy in modeling of the ARF or kit is sacrificed for the average RC pilots, so we are able to fly the planes we dreamed of flying as little boys or girls.

Pete

I built a 1/4 scale BUSA DR-1 with an O.S. 120 AX (2S) turning a 17x5 wood prop and it flies quite well, but I also did a lot of things to it:

1. Put in all the right and down thrust I could without the prop hitting the cowl.
2. Set the horizontal stab up so I could shim it under the leading edge to get some positive incidence. (About 2 degrees at present)
3. Set all three wings to 0 incidence (in relation to the fuse deck)
4. Put twice the engine displacement (cid) in oz of lead in the right wing tip to counteract the torque. (1.20 x 2 = 2.4oz)
5. Use a lot of aileron differential.
6. Propped it for no more than 40mph, as anything faster is not realistic and results in it trying to put its nose into the sun.
7. I balanced it exactly where the plans said to. I did the calculations as I was curious, and it was bang on 25% of the MAC. Is very stable and doesn't nose over.

The three main flying rules with DR-1s, which the guys here have all mentioned:
1. Never, ever, ever attempt crosswind takeoffs or landings.
2. Be careful on final approach to landing to maintain enough power that the bird does not fall out of the sky due to all the drag of the design.
3. Always make wheel landings. If you attempt to flare, the wings blanket the tail section and you lose all directional and pitch control.

Building this plane was my graduation from a GP 60 size DR-1 ARF. It had none of the mods mentioned, and was a miserable SOB to fly.

My vote on roll quality: it's there, sort of. I mostly use the ailerons to keep the wings level during TO and landing. Turns I initiate with a lot of rudder and elevator, and generally end up using opposite aileron to keep it from overbanking.