Sneasle

Ok guys, time for round 2.

I finished all the planes, the DNU, the 'stang, and the 2T (all can be seen in my profile hanger) and took them out to the field this past saturday.

I installed Berg recievers in all of my planes. 2 of the new hardshell 4 channels and an older 5dsp. The glider also got a servo added to the front bay which attached to the fuel line to serve as a cutoff since i had a 4oz tank attached to a Surestart.

The mustang had been stripped of its covering and repainted ( my clear cote wasnt fuel proof. What did yall recommend again?). It was nose heavy so we balanced it with some clay at the back and placed a penny on the right wing for lateral balance.

DNU was covered in light blue cote with orange stripe on the bottom for contrast and then decorated with decals. Decals survived the fuel, but not the cleaner i used to clean off the fuel at the end of the day.

We tried out the mustang first. Got it on the test stand and got it running. We tried to taxi it off only to find that it wanted to nose over. After a quick bend of the landing gear it was ready for another shot. I was kinda worried before my coworker got it in the air because it wasnt sounding right on the starting stand. It had also hydrolocked on us once on the stand. Well, he gets it in the air and goes to start his turn when the engine dies. I have got to give Jim credit, he did an amazing job of swinging the plane back around and almost got it into the uncut high grass on the runway but he just lost too much airspeed and it ended up goin into a smallf ir tree about 4ft off the ground. Not a scratch on it. Only problem is, it had hydro locked again.

So i figure the engine is flooding, but im not sure why. Its possible that because of the resricted area that it is runnign hot on the stand and therefore needed a richer setting, but then once it gets in the air and gets soem airflow that it is cooling down and flooding. Im not sure how to avoid this though. I dont think it is fuel tank placement as several guys at the field checked that for me. Aside from that, Jim said everythign on it felt great. After that incident i decided not to press my lick and grounded it.

The DNU gave a good show.. .. if you wanted a laugh. We forgot to balance it before we tossed it, and it was very very very tail heavy. It flew in a constant state of stall. We got it back and balanced it and switched form the 5.7 to a 6x3. It took a mouse ball (after trying to use $1.50 in quaters) plus the 2oz of fuel to get it anywhere close to balancing. We gave it another toss and it was still way to underpowered. Ended up crashing and breaking the prop.

So, the DNU needs a heavier and more powerful motor. I have 3 options. the AP .061 and .09, or a norvel .074, if Tim's LHS still has it.

Then we gave the glider a toss. Same problem. Way to underpowered. tried to move a little bit, but then the wind changed direction and flipped it over, breaking the brass wingtube out of the outside panel and snapping my rudder off. Only the covering held it on.

I had the #3 cylinder SS on the DNU and the other one Tim sent me on the Glider. The engines ran great, real screams, just not enough power.

If anyone has any suggestions about the stang, please speak up. I might end up starting another thread since I have no idea where to start from here.

If yall want pictures of the DNU, just holler.


edit: I am also gonna be looking for somethign to build to put these two Surestarts on. Any suggestions? a blink maybe?

combatpigg

My Feedback: (3)

Hmmm.....not surprised to hear the Mustang was nose heavy, goes with the territory, but I'm sure that it is curable by installing a 350 NIMH as far back in the fuselage as you can stuff it. Is the engine mounted inverted? If you are truly experiencing hydralic lock, with an engine that thousands of other guys have used successfully in a thousand different set ups, all I can suggest as a quick test would be to take the baffle out of the muffler [you should have done that already] to reduce fuel pressure slightly. If that doesn't work, you probably haven't set the part throttle airbleed or needle, if this is when it loads up and dies. Some planes tend to siphon fuel more than others, get a pair of hemostats and use them to avoid flooding while the plane is sitting around gassed up. BTW, What prop are you using?

The DNU shouldn't build tail heavy, you must have deviated from the plan somehow. A good running SS has plenty of power to fly one of these planes with authority. I think mine came in at 11 ozs or so, and a SS can almost hover it.

My experience with 2 meter gliders is that a weak .049 won't cut it. A screaming TD with a 5x3 will pull them up fairly well. There is a line somewhere, that your engine / prop combo needs to cross yet.

KidEpoxy

Sneasle
The DNU- You have that bonus servo for the rudder in there?
Where is it, can it be moved... read that as You Should Move.... move that sucker foward to get rid of the DNU tail-heavyness. Or move it to the workbench and just tack the rudder straight for testing. Could also try mounting the motor on some standoffs, like some 3/4" blocks between the engine back and the firewall to get more FrontMoment- more balance effect from same weight motor

What is your AllUp weight, wet, for the DNU?

hogflyer

Is the Mustang engine inverted? If so, sounds like it siphoning fuel while sitting. If this is the case, you'll have to empty the tank when the plane is on the ground and fill it just before you fire up the engine. How are you setting the mixture - with a tach or by ear? You may also find you'll get the engine tuned to run good with the plane upright, but if you roll inverted the mixture will change and you'll hear the difference, which will probably be a lean condition.

For the glider, I've never had much luck getting one on a power pod above 75'. Get a high-start and launch the glider with the engine running. You'll find after a 30 second high-start launch you'll still have several minutes of powered flight (or very slow decent). I used to do that trick with 2 meter gliders in Florida and then catch thermals for some very long flights.

Also, don't try to fly any plane without balancing it first. Like CP & KE suggest: move radio components around if need be to help achieve a good balance.

combatpigg

My Feedback: (3)

The only way I've ever set up a .15 in a "1/2A" P-51 is with the engine side mounted, and the muffler acts as a belly skid.

Sneasle

The mustang I am not worried about balance wise. I have some cells sittign around that I am going to make some packs out of (BTW, what do you guys use to connect the cells inside your packs?).

The engine in the mustang is in fact mounted inverted. There was no baffle in the muffler. We took it apart at the field to try that. I haven't touch the airbleed adjust screw, but I thought that was only for low end/idle adjustments? We tuned the needle by ear this time. The weekend before this we did it with a tach. It really sounded to me like it was running rich, then again, i didn't set the needle, the club instructor did (when I say "We" , It includes me and him.)

When we had the mustang on the start stand we tried to trouble shoot the floodign a bit. we got it running and then leaned it out and turned it a bit rich (still being run in) and then me and another guy each got one wingtip and pointed the nose straight up. the first time we did this it died. We then did it again and Jim made some needle adjustments so when we did point he nose up again it wouldn't die. I'm not quite sure what this would have done to it in terms of rich/lean ness in the air, but Jim seemed pleased with it. prop was an 8x4 (that is what the manual recommended)

The DNU is a bit heavy, I do know this. Its about 15oz rtf i beleive. The only "mods" i did to the plan was add rudder, and i did that by adding 1 hs55 and did it with a pull pull system, so the weight should have been marginal and counter balanced by the fact that i am using a 2oz tank instead of a 1oz. it had only 3 servos, an hs81 for aileron, and hs55's for ele and tail. both tail servos are situated in the bay right behind the wing as close to the wing as i could get them.

I also know that I overbuild the tail. Because of how i built it (you can check the build thread) the tail is heavery then it needs to be, but not by that much. If i need to, i will go in and strip the covering off and take the dremel and hollow out the sides to cut out on some weight.

I am not so worried about this DNU. If ya'll say the SS should fly this thing aggressively, then I will build another one for the SS. (and maybe a blink, will the blink fly on an SS?) But with the info i have given yall what would you recommend to get his DNU in the air. In all honesty, scrapping it is not an option (the gf would kill me since she is the one who designed the coverign scheme for it)

I have resigned myself to the SS not being enough for the glider. That glider is built in a way that it cant take a crash any harder then what it took. I am thinking about going to a speed 600 or equivilent e-power system for it to take advantage of the cleaner power and the folding prop option. Any thoughts on what would be goo along these lines?

combatpigg

My Feedback: (3)

I would put the baffle back into the muffler and set the needle with the model pointed straight up. you want to be able to quickly pinch the fuel line without the engine sagging, then back off just a click or 2. The 8x4 is maximum load, so at the first sign of the engine sagging in flight at full throttle, bring the plane in, and move the needle out another click. The other way to tune is from the rich side, same idea. You should always be alert to any signs of sagging, especially with a new engine. If you prop it with a 7x5, the needle will be less critical. During all the gyrations at the field, was anybody looking for air bubbles flowing through the fuel line? This will cause needle setting confusion.

Sneasle

There is not baffle in the muffler. We looked for one to try and remove it to ease the pressure, but there wasnt one to remove. The manual says this engine can take up to an 8x5. 8x4 is the recommended break in and general use prop. I am goign to try and see if i can get it to flip start here some tiem this week and run it rich for a tank or two to try and break it in some more. No, we didint look for air bubbles.

combatpigg

My Feedback: (3)

Is this engine either ABC, or ABN? I've lost track of what you got. It seems that every OS or OS clone would come with a baffle, but I guess not. If the engine flips easily between compression strokes, holds a seal at TDC, and has a clear exhaust residue, then the break in period should be over. Running a well designed muffler pressure system should reduce the engines' tendency to be sensitive to its' position relative to tank position. If it were my plane, I would ditch the gear, fly it mostly WOT and use the throttle mainly as a shutoff. without the gear the performance of the plane goes way up, it looks more like a war plane should, [instead of roaring around with the gear down], and ultimately I think belly landings in the grass or on a canvas runway work just fine and you never have to worry about the gear getting messed up. If you are just learning, this is the kind of plane where you either nail the wheels down landing perfectly, or get out the glue. Belly landing a plane like this is so much easier.

Sneasle

I am pretty sure its an ABN, aluminum crank and most other parts, nickle plated brass cylinder?

it could still use some more break in time i think. It's only had about 5 oz through it.

edit, i agree totally with taking the gear off, just he guy who was test flying it wasnt comfortable giving it a hand launch right out of the gate.

ptulmer

My Feedback: (5)

Sneasle, my built-up DNU is coming in around 10.5oz using monokote(heavy). I'd say your 50% overweight. Can you say "grossly obese"? Check all the components and see where you can lose weight. After a few repairs, my first one with the ACE wings weighed 14oz and didn't fly so well. So bad in fact, I retired it to the garbage can. Tell her it's just too pretty to fly! It should get airborne at 15oz, but it won't be as fun to fly with the too-heavy wingloading.

Good luck with the Mustang. Pains like this are to be expected, especially to someone young enough to be impatient. Well, I guess impatience is relative. You're building from plans and kits, so you are far, far ahead of your peers! (should I say faaaaaar ahead?)

Sneasle

ok. I am taking a guestimate at the weight since i dont have a scale. The mustang came in right around 30oz, and the DNU feels to be well under half that. I'll keep that in mind and maybe strip it down and take the dremel to it.

eroc144

My Feedback: (1)

Hey Sneasle,

It sounds like your 'Stang engine would benefit from more bench time. I had a new Norvel .049 that was problematic like yours so out of frustration I tossed it on the test stand and ran 5 full tanks through it before putting it back on the plane - Runs like a champ now. Not sure what kind of stand you have, but after a few tanks I'd try inverting the engine so it's running in a similar setup to your 'stang (engine and tank orientation are the key items here). I built a small stand-alone unit out of plywood scraps that I can invert, tip vertically, etc. Keep it on the stand until you've really got it figured out, and THEN put it on the plane and take it to the field. It'll make for a much more enjoyable field experience!

The glider issue puzzles me. I have several gliders that I've added engines to and they all do just fine with a Norvel .049. What size prop are you using? I generally run a cox 5x3 on my .049s and they will loop and rudder roll and really motor around (I've got an HOB 2x4 and some old non-descript 6' span glider).

You've probably done this, but make sure that your planes are balanced per the plans before giving them a toss. A little nose-heavy is almost always better than a little tail heavy and you should be able to slide your battery pack and receiver around to fine tune your balance. When I build I try to leave myself enough room in the fuse to move things around, and once I've got it balanced I usually add some type of tie-down to keep things in place during flight.

I think I need to take some building classes from CP & PT - My DNUs all weigh in around 13 - 14 oz. Then again, I do have a throttle servo and a tank, so that's at least an extra ounce. All in all, my DNUs fly pretty hot with a Norvel .049 and 5x3 prop.

EG

ptulmer

My Feedback: (5)

Eroc, the big secret is to NOT buy balsa from the hobby shop. Most of'em don't understand the need for light wood. The 1oz tanks weigh 1oz, so I'm using a balloon tank. And, I'm using a 300mah nimh battery that weighs half of it's nicd brother. Those last two elements could account for 2oz. Plus, I'm using surestarts that weigh quite a bit less than the Norvels. (and put out less power) Right off hand I'd say you're building techniques are exceptional and the more powerful motor and only slightly higher weight is just right.

Sneasle, Don't guess at weights like that. Go pick up a postal scale for fifteen bucks. (or scrounge around for a free one like I did) They measure up to two pounds, so bigger planes have to be weighed in pieces. The springs in them go bad with age, so measure something of a known weight to see how far you need to adjust it.

KidEpoxy

Sneasle

The DNU-
Before you give it the Termite Treatment, pull the rudder stuff & see where you are.
Get rid of a heavy tank if you have one in it... go with a 3/4-1oz capacity balloon to cut weight... flight time dont matter if you cant keep it in the air for 30'.

Swisscheesing the 1/16 balsa doesnt really cut that many grams, you need to identify the heavy objects, & put them on a diet.

You can do GlideTests of the plane, loaded up to the point just before you clip&flip... just dont. Take it to some tall soft grass, and give it a few tosses to see how it glides. Dont try to fly it, just a controled decent & landing.... it's basicly the last 2-3 seconds of a flight without the flight. You can even start small & toss it from your knees to check the first time... no sense in getting a 7' nose-in if you can trim/adjust from a 4'. The plane should be able to take a bunch of green tall soft stuff no problemo from a hand glide toss... even a spearchucker hurl 30-40' should be no problem once it is gliding ok.

flyinrog

My Feedback: (1)

You can always take it to the post office to weigh it. all they need to weigh it is a zip code..I did this for a while before my sister got me a scale for xmas...

Sneasle

hhm.. ok..

the rudder system didnt add much weight. all it added was the weight of the extra hs-55 and the wire needed for the pull-pull.

it might be a combination of a 4 cell AA pack and the 2oz tank. Despite that fact, It is still way too tail heavy and removing weight from the nose(ie battery and fuel tank) isnt goign to help that.

You want me to take the rudder off? as in, cut if off and see what happens? I can pull the servo out if you like, but the wires would have to be cut out if you want them removed. I could try going to a smaller diameter pushrod, but that might not be worth the small amount of weight it would save. Is one extra hs 55 in the tail really going to cuase that plane to become so tail heavy? the hs55 is what, 8-14 grams, somewhere in there?

Sneasle

we have a couple of scales at work i could use. just gotta wait till after the boss leaves. I think I would feel kinda stupid walking inot the post office asking to weight a plane.

KidEpoxy

try taking it to the supermarket... I waited till after midnight to take a plane into the market to weigh it... less folks to say No or Too Busy. I just walked in and over to an empty checkout isle, set it on the scale, and was walking out before anybdy could say anything. Did get a few odd looks though. But it was a little 20"span plane, bigger might be harder

D Bronk

That Battery should be made from 2/3 AA cells nestled right to the front.But that won`t help with tail heavy ,if you have larger cells in a pack, thats Adding nose weight Could you move all your servos forward more??Maybe Lose the pushrod in the tail,and go, pull-pull on that too.Post a pic of your DNU lay-out ,if possible.

Sneasle

Sure Dave, I'll post a pic tnight once I get home.

I can most the tail servos forward, but then they would be in the wing bay and then could risk bumping into the aileron servo.

I dont really have an 2/3AA batts anywhere. All i have to make packs from are 700mah sanyo nicads. I do have some round nimh batts that are ~300mah, about 1.5 inch diameter, but they almost feel as heavy as a nicd cell.

ptulmer

My Feedback: (5)

Sneasle, that's a strange nimh battery! My 300mah batteries weigh just over 1oz for four cells! They're slightly shorter than standard AAA batteries. The 700mah nicds should weigh more than 1oz each, meaning a ~5oz receiver pack. That's about half of what the whole airplane should weigh if you're running a SS.

Tim Wiltse-RCU

There is no reason a SS can't fly a DNU(unless it weighs 3 pounds). Not to pick on Patrick but last year at the reedie race because of the covering his SS was turning so slow you could count the prop turning as it went around the course. To help with the tail heavyness stick a couple 1/4" hardwood blocks under the back of the engine. that will stick it out front more plus you can then use the chock tube that the SS's have. I'll send a couple down to you. I need to send you a couple wrenchs too. Don't forget to balance the plane DRY. If you balance it wet as the plane burns fuel it will only lead to a tail heavy plane.

LAter,
Tim

Sneasle

ah, ok, then i need to loose the reciever pack. That could be the cause of alot of this.

any good sources for smaller packs? I don tmind making my own either, but i am nt sure what is best to use to connect the individual cells.

edit: didnt see Tim's post
.. well, it doesnt weight 3 lbs, but it sure didnt fly very well, or much at all. it broke the prop when it came in the last time so now i am down to 1 6x3

KidEpoxy

Instead of drilling out the Fuse, maybe he needs to drill out the batteries to shed weight