Originally Posted by corsair nut

the ailerons and ruddervators are not mixed. rather it has conventional ailerons, and sense its V tail, the elevators are also used as rudders,

That's what I meant to ask- sorry, wasn't clear.. It seems like most foamie attempts at this airplane have set up the ruddervators incorrectly and had control problems. I knew it'd work once they were set up as real ruddervators!

The violent behavior at speed-- do you think that might stem from an adverse roll problem?

its alot of fun, just know that the plans on that link kinda suck because they were scanned in, and the pages dont match well, requiring you to "fill in the blank" if you guys build them, .

You wouldn't be volunteering to make a better set, would you? Either way, thanks for the thread and the CG!

yeah im going to make plans for the 54" long twin EDF!!! just got back from 3 more great flights with "LIL PAV" last night i reinforced all the joints with gorilla glue, and added a exhaust tube, to see if the theory on turbulant air over the stabs was true...made 1 flight, the wind was almost dead, and it flew great, but still showing that pitch up near stall with the power off...as soon as you would touch the elevator, she'd flare straigt up! so im thinking, still tail heavy, so another nickle wen tin the nose...much better! slow flight was no longer "butt clenching" but rather pretty tame. i think im going to add one more and it should be perfectly stable. i deffinately believe the fan being so high up is causeing a little "wobblyness" in straight and level flight...also noticed that for loops to be complete, you need to keep the speed up at the top, other wise the stabs go inefective, and it hangs there pointed straight up! i guess you could say shes a venture into EDF 3D! it really flew nice with the extra nickle, and i think one more is the ticket...i know the larger version with the fans mounted lower will prove to be very stable with the proper CG. anyways, look here later for some new sweet vid!!!

heres the link to the new vids. the vids are longer lengths, for more enjoyment! also, notice the smoke in the vids...this is from the out of control wild fire that has been buring for almost a entire month now! today was the worst ive seen the smoke. enjoy the vids!!

https://www.rcgroups.com/forums/show...70#post6131036

Hi Brent,

I'm curious, where do you think your cg has ended up? My guess is that it needs to be at about the 15% MAC location for this airplane. That pitch up your seeing is due to the configuration. The full size aircraft had a divergent stability mode in the mid range AOAs. It wanted to pitch up once it got to a certain AOA then would become stable again once it was out of that AOA range. To tame that out on a model, the airplane needs to have a pretty forward cg. Very cool project, look forward to seeing the twin!


Chris

Heres a nice site with a little info but also some better images of the few that exist for the YF-23.....www.voodoo.cz/yf23/

thanks Chris, yeah, accually it is right around 15% right now. i think im going to move it forward another 1/8" or so, and it should really be sweet! yeah, it was at about 20% the first flight, and it flew great, until just like you said, the pitch was very tame at low angles, but it got to a certail angle and would pitch straight up and come to a dead stop. this happened on my first landing atempt, and it did it about 3 times in a row as i tried to regain flight...luckily its pretty light and i was able to power out of it. now the cg is about 3/8" fwd sense then and that tendency is just about compltetly gone, it only wants to do it alittle. also noticed it doing this pulled out of shallow diving turns...it would snap up as soon as i touched the stick to pull up, and yet it flew straight and level with out hardly any trim. i figure this is caused by the extremely wide wing root, and the lifting body style nose on this baby. my 50" long F-20 does the same thing, just not as violent. that nose really creates alot of lift at anything above 10 deg of AOA. thats another reason why i can do knife edge passes with my F-20. the "LIL PAV" is alot of fun, and after the baby, and my A-4, thats next on the drawing board....and when i say drawing board, thats what i mean! so far ive desighned and built and flown 5 models with a pencil and ruler! i have a cad program, but need to take a colledge class to learn hoe to use that sucker! im looking forward to the big version, and i really enjoy flying challenging models...i easily get bored, and this one has been a challenge, and is quickly becoming a favorite of mine.

thanks for the link to that site, ive been there a few times before, its a pretty cool site. i have the declassified video too, although there isnt much flying vid in there....hey, did you guys know the "FA-22" had its main gear colapse a couple weeks ago? what a piece. i still get bitter about the YF-23 and the F-20!

YEA hoser i'm with you on that. hey also your pitch is'it helped by the high mounted motor. it is pushing the nose down and you've trimed it for level flight, when you come off the power it's not pushing the nose down. so it pops up when the power is cut .you should try some down trim for your landing and see if that helps. hey also i need my hinges... and did you get my e-mail about helpping me dig my ditch. JET MENG could you give me the Dims. on your mini retracts...length width and height...also how much does it weigh(complete system) thanks JET if they are the right size i might be ordering a set from you guys. thanks.

Heres another profile plan i found a while back, forgot i had it on hard drive till tonight. Belongs to a Pete Hawk...he deserves credit.

yeah, ive seen that plan before, just not as scale as i would like, but nice plans none the less. CG seems pretty far aft.

DAD, i dont think the motor being that high was causing it to pitch up under do power conditions...i tried some gliding yesterday after movin the cg forward, and it was great. only pitches hard when alot of elev is used...but after i moved the cg, it was much tamer. plan is to move the cg just a little farther fwd.

heres what i did tonight...i wanted to get rid of the nose weight, and try to get rid of the top heaviness i have seen with it. so i removed the plywood mount, and moved the fan fwd about 2.75". this allowed me to get rid of the weight, and also move the cg a little farther FWD. also, between the nose weight, and the weight of the epoxied in plywood, i lost about 2 oz (yes!) and i will throw a quicky paint job on her (gunship grey) so she looks better in the air...which means i will gain another oz back or so. atleast i got rid of all that nose weight, and moved the cg forward at the same time, while also lowering the fan. so we'll see what all this did. i still want to put some gear on it, i think that would be fun... until next time...

ps..see ya tomarrow dad.

would you believe the CG is 1" in front of the spar??? holy cow! that will make things interesting for the larger version!

found this some where-seem to remember tailerons didnt work well and aler-elev
worked better as per builder.

Tailerons shouldn't work-- it's a V tail, so you get yaw input one way and roll input the other way when you deflect them. You've gotta have separate ailerons to counter the bad roll. (Or drag rudders to counter the yaw- whichever..)

Mike- is there any more info on those plans? Projected weight or etc? I have a 5000kv motor lying around looking for a home...

Rdeis...i got those here on rcgroups...just do a search on YF-23 and they'll show up along with the build Hawker was doing......

well, just got 3 more flights today. you can tell its 2 oz lighter, flys very nice...also the cg is slightly farther forward, now the pitch up snap is all but gone, and its very predictable. i tried stalling it, putting it into a spin, but to no avail, shes pretty darn stable at this CG. a full up power off stall reulted in a slightly nose high( 5 deg or so) pancake flat fall. it wouldnt snap, or do anything weird...it looked pretty cool! also, experimented with the rudders some more........... holy snap roll bat man! those puppies make it snap hard. first with full rudder at a slow-medium speed will begin to yaw in a flat turn type patern...then all the sudden it will snap roll extremely violently...just ask AIR SALLY...he can second that emotion! also, the rudders do work for yaw, but like i said before, only a little stick is needed...any more and she'll snap like a mo-fo. i was able to do a large flat turn, that was cool! also tried using the rudders during a aileron roll, made it snappy and looked really funny! now you can accualy do some slow high AOA passes with out worrying about the pitching up. the FWD CG really tamed her. the dutch roll wobblyness didnt really go away with the lower motor. my dad said to try putting the ruddervators at a more vertical angle...this may help this wobblyness, but also the fans will be on the horizontal centerline on the twin verison., maybe i'll put the batts below the centerline as well. in any case, shes alot of fun, and you'll never see anything shaped like that in the sky unless you build it yourself!

YEA it snap rolls like a 3D type airplane. it does have a dutch roll or wobble but it does'nt hurt anything we saw it do some weird things when CN tried to spin it ...but just let go and it is easy to fly away from. the flat stall he did was neat ,i believe it would have did a"auto land" if he held the up all the way to the ground.put some grear on it next CN .