masupilami59

All, I did the maiden flight today. CG right at the leading edge of the bottom wing as some of you recommended. Start was easy, but the plane climbed up as I gave more power. Thus, I set down trim as much as possible to keep the Pitts on a straight and horizontal line. I was not very happy with this behavior. After landing I removed the top wing and gave it some more negative incidence by adjustments to the baldachin and the wing connectors (see 2nd image below). The second flight was absolutely amazing. Straight horizontal flight after some few clicks down trim, no tendency to climb up while giving more power, knife edge flights with only some few corrections on ailerons and stab, ... I still have to finetune the Pitts, but it shows already its strong capability for impressive aerobatics! Thanks to all of you for comments, discussion and your very valuable recommendations!

Bigblock1031

Glad to hear to went well. I'm surprised to hear about how much down trim you needed. I see everyone talking about their wing incidence and I've never even thought to check what mine are. Looks like an incidence gauge is in my near future. I don't think I really needed much trim for level flight but I guess I should check it anyway. I like your wing adjustment blocks. Very nice.

masupilami59

Thanks! Yes, I would recommend to check the incidences! The upper wing should definately have less incidence then the lower wing. CG at the leading edge of the lower wing is correct and works fine -> I was able to hold the Pitts in a torque roll, it's really a great plane which guaranties a lot of fun! Good luck!

KI8FR

Do they still make this plane. I cant seem to find it..

CaptRKO

My Feedback: (3)

Long gone! I have one and love flying it! Didn't need any trim and flies like a raped ape on a G-26! You might find one online second hand.

masupilami59

... but it is still on the website of the producer: http://blackhorsemodel.com.vn/?produ...log=bipe-plane
There is also a list of distributors available. In germany, some online shops have offerings around 300 € for the kit.

Bigblock1031

What on the fuselage are you using as your baseline level in order to Measure the incidence? I know the fuse has to be leveled first then you measure the wing, but what are you using as "level" on the fuse itself? I used to think leveling the horizontal stabilizer was the way to go but I was told that's not always correct and to instead level it by the datum line. Well who can tell me where to find that tidbit of information lol.

dgliderguy

Bigblock,

Remember that the important data point (i.e., decalage) is the difference between the wings and the stab, irrespective of the fuselage. The "decalage", (sometimes called "longitudinal dihedral") determines the pitch characteristics of the airplane, and the fuselage is not a player in this (assuming a non-lifting body). With a two-surface airplane (one wing and one stab), you can either zero out the stab and measure the wing, or vice versa. You are looking for the angular difference between the two. I tend to favor one-and-a-half to two-degrees of positive decalage for best results, for most of my airplanes.

A biplane is a bit more complicated, in that there are two wings, but they both contribute to the same moment about the pitch rotational axis, so what you are interested to know here is the angular difference between both wings, and with the stab. My BH Pitts measures "two-two-zero", which means both wings are parallel to each other and both are angled leading-edge up (positive incidence) two degrees from the stab, with the stab set at zero degrees (perfectly horizontal).

Bigblock1031

Ok I think I see what you're saying. We're trying to measure the angular difference between the wings as compared to each other or to the stabilizer and not to some magical line on the fuse. Well that certainly sounds a little easier. Does yours seem to perform well with a two two zero setup? What would be ideal for this type of plane?

dgliderguy

I've been totally happy with my two-two-zero setup. Plenty of pitch stability at all speeds, gentle down-elevator needed in inverted flight, and a good stall at any bank angle.

Bigblock1031

Well I sure do appreciate the help. I think I'll pick up an incidence meter this week. I haven't noticed any bad tendencies or habits with my BH pitts so who knows it might be right where I need it to be anyway. Doesn't hurt to check though! Thanks again.

masupilami59

Bigblock,

I always use the horizontal stab to level the fuselage. This worked absolutely fine with all my planes. But that doesn't mean that the stab is horizontal during the flight, too. That might differ. It depends on CG, incidence and the motor down thrust. My BH Pitts needs some little down trim to have a horizontal flight.

Bigblock1031

Yeah I think I was getting confused with leveling the datum line when it comes to finding the CG. Not with wing incidence. I would always balance my planes by making the stabilizer lever. I was told that's not always correct being that while in flight the stabilizer may not naturally fly with a level horizontal stabilizer. Which honestly surprised me because I always thought that it would naturally fly with a level attitude. That's how I've always balanced them without any major issues, however wrong it may be. That's when I was told to level the plane according to a horizontal datum line. Which I still don't know how to acquire.

dgliderguy

...and in truth, the advantage of radio-control is we have adjustable decalage in flight. In my old sport free-flight days (as a kid who was too poor to own a radio), I set the positive decalage for a well-trimmed glide. With this arrangement the model wants to climb under power, so downthrust was required to counter this. Rudder-only airplanes like the Mambo and Live Wire and Tri-Squire had noticeable downthrust and plenty of decalage. With elevator control, you can trim the elevator down for high speed (i.e., reduce the decalage), and then trim back for slow speed. We have it good.

I think it would be advisable to divorce yourself from making any CG setting based on statically-balanced stab angle. (Remember that all-flying stabilators have no stab angle.) The correct CG location can best be determined by the way the model flies. Too far aft, and it will not settle down in level flight or in turns, and will balloon unexpectedly in the flare. Too far forward, and it will require gobs of down elevator in inverted flight, the stall will come quicker, and the elevator will poop out on you in the flare on landing. You can feel it.

flycatch

My Feedback: (26)

http://www.rc-airplanes-simplified.c...-airplane.html This all you need. I had the same model and your right the instructions provided in the manual are wrong.

masupilami59

All, as I mentioned earlier, I started also with two wings parallel and my Pitts climbed up while giving throttle. So, I had to give down trim.
I wonder, why dgliderguy's Pitts is flying fine with a two-two-zero setup as written in #183. I guess, that he gave more motor down thrust then I. Could that be?
To avoid the climbing up of my plane, I didn't changed my motor down thrust. I left it as it is defined by the incidences of the motor dome. Instead I gave the upper wing less incidence then the lower one. To achieve this, I modified the wing struts. This was the end of the climbing up tendency, and I am happy now.
For those of you, who like to check this out, too, I have attached a pattern and some images of my modified wing strut.

masupilami59

...quickly another question: could anyone provide me fotos of the logos at the fuselage of Charlie Hillards Pitts? On the web I found images of the Champion and the Pennzoil logos, but I couldn't identify the others. I use inkscape to draw the logos by myself, so a simple photo showing the logos clearly is sufficient. Thanks in advance!

Dinkster75

hi, just gone one and am goign to stick a dle 30 in her (i know... over powered, but i like a lot of power... gets me out of trouble )

i see how to strengthen the motor box with triangle stock, and the carb will need to penetrate teh firewall, but at the moment i cant see a secure way of fitting the tank.

whats the best idea, modify and try to install directly ove teh cg so tanks emptying has minimal effect on balance?

any pics of similar instals would be really apreciated.

been searching google imaged for "blackhorse pitts dle tank" but so far have come up blank..

Cheers

masupilami59

Dinkster75,
Mine is overpowered, too. Have an OS 160 in it. Great fun! The tank is installed as recommended in the manual. No problem and works fine!. Since the CG is close to the leading edge of the lower wing, you would have to think how to fit the tank there. In this case, the motor might need a fuel pump if the exhaust pressure is not strong enough.
I'll send a photo how it looks inside of my Pitts later this day.

masupilami59

the warm winter in bavaria makes it happen: Pitts S1-S, modified as mentioned in my posts here, in the air: http://m.youtube.com/watch?v=MIhV_kpMclQ

Dinkster75

i need to bust though the firewall like http://www.rcuniverse.com/forum/arf-...l#post10490149 so i loose the hole at the front of the firewall to steady the tank, wondering how the other dle installs took care of the tank,i see glow can be installed as normal, but once you loose that locator hole on teh firewall i think the tank would flap around

masupilami59

I fixed the tnk with some foam material und rubber bands. Works fine.

Bigblock1031

What I ended up doing with my tank after cutting the hole for the dle 30 carb was to glue in a piece of thin plywood from side to side of the motor box, about an inch aft of where the carb stuck through. Then cut a hole in the center so it would hold the front of the tank the way it would have. That way the back of the tank still sits in the rear supports as it should and its held up front by the neck of the tank. It ends up only moving the tank aft only about 1 1/2".

CaptRKO

My Feedback: (3)

Just broke 150 flights on my PItts. I kinda call it "my toy" as I have lot of 40% that I fly and the PItts is just a fun little aerobat to throw in the truck and go fly.

I wish they still made the kit....I would get another.

Dinkster75

perfect, just what i was looking for, also did you find that the included tank's bung was ok for petrol of did you need to change it, i have a dubro petrol bung that will fit if i force it...