Kahuna,

Did you try some lighter lines yet? There is a big difference between .012 and .015 for that size ship.

George

Not Kahuna, but from many years flying them, 52 X .015 are fine for a per plan "Peacemaker" powered by the plain bearing Enya .15 driving an 8 X 4 combo. .012 are lighter and arguably less draggy, but marginally thicker .015 lines (usually recommended as standard for class) won't ordinarily be a cause of the symptoms he is experiencing IME with either the "Peacemaker" in particular or that class of model generally.

I have similar problems with my JR Flightstreak. I got back into control line this summer. I had not flown one since I was in junior high 30 years ago (been flying RC since then). This summer I finished up a Sig Chipmunk that I have had for years and took it to our RC field. It is powered with a HP40 flying on 70 ft .015 lines. It flys great. I could not believe how well it flies. I do not remember any of my other control line planes flying that well. Most of my previous control line stuff was small 049, but I did have a couple of 35 ships. Since I was having a ball with my new ukie I figured I should build something some of my RC buddies could try their hand at. I had a Flight Streak Jr so I stripped and recovered it. I tried it on 42' .008 lines. It flew very fast and was very twitchy around center. Also very nose heavy. I moved the cg back and reduced elevator travel. It flys better but still not great. It will loop but it shudders all the way around. Seems like it is constantly stalling and recovering. It is still sensitive to elevator and seems to fly heavy. It flys on power instead of the wing like the Chipmunk does. I let another control line pilot fly it (he is a lot better at UC than me) to see what he thought. He tried a couple of wing overs and then just flew level until it ran out of fuel. He did not like the way it flew either. Said he was afraid to loop it. I know it is built straight. I think it is just too heavy to fly very well. It definately is not a good trainer but I do have a couple of RC pilots building some ukie ships now.

David

Where does your Jr. Flitestreak balance, and how much elevator throw do you have? Something is wrong here.

These two statements appear self-contradicting. Could you elaborate what you mean by "twitchy around center"? I interpret it to mean very sensitive to any (small) control input from straight and level flight (relatively unstable). That's the sign of an aft CG, not a forward one which it'd be if nose heavy. With the CG displaced extremely aft, the model may also have a tendency to porpoise which can range from minor oscillations to wildly uncontrollable in the extreme aft CG case. If the CG is excessively forward, the model will be unresponsive to control input and have a delayed response to control input requiring anticipation which can incite PIOs though overcontrolling. To the unfamiliar eye this may be mistaken for porpoising but with larger amplitude and lesser frequency, but is in fact PIO induced. If the CG is way forward, characteristically, loops will be very large.

Although strictly speaking stall is a function of angle of attack, moving the CG aft will predispose the model to more easily exceeding the stalling angle with small control input regardless of control differential -> reduced deflection. If it's heavy as well and you try to tighten up the loops, the wing may dynamically stall as the engine tries to drag the model through the manoeuvre with power. It does sound as if your wing loading is excessively high (heavy model for class/wing area) and this is what is happening.

Me too. That's certainly what it most sounds like as the primary cause, with the CG issue just aggravating the situation.

Models without much wing area and thinner section like SIG's Akromaster and the Baby Flight Streak/Flight Streak Jnr/Mini-Peacemaker fly magnificently in class if you buiild them light, but haven't much leeway for bloat. At that size and area, just a couple of ounces can make the difference between a solid performer and class dog, so you need to take everything into asccount when buildng them from the weight of the wood, through "more epoxy doesn't mean stronger just heavier", white glue is heavy, less is more <performance>, Monokote weighs a lot less than dope and Koverall (even where applied by a skilled hand), and of course, engine weight and fuel tank size. It all counts on a model in this class. As a general rule of thumb, the smaller (capacity) the model, the more critical. OTOH, that's why the Peacemaker and Smousen are better models in class (versus Akromaster or Flite Streak Jnr) with a contemporary Schnuerled .15 even fitted with a silencer. Because they both have a significantly thicker section and 20% more area, they can carry that small (2oz) weight blowout without total loss of performance - ie: turning into an utter dog. Plus they fly slightly slower (higher iinduced drag) allowing more time and ease of increased precision. Hope that all helps. If it's heavy as many fisrt attempt models built when returning to control-line are, then it'll never aerobat well. Put it down to experience and build another.

Sounds like you got it right with the Chippy though! SIG's Super Chipmunk is unquestionably one of the best (& prettiest) sport flying C/L kits out there. Perhaps why it has remained a perennial favourite throughout C/L's twilight?

I'm in agreement, except that the Jr Flitestreak and Flitestreak don't have particularly thin airfoils. Lite is good![8D]

Hi Jim

Just to clarify, I didn't mean flat like some of those British section designs, rather thin - relative to the Peacemaker and Smousen, or full size Flite Streak - all of which are quite fat sectioned in comparison.

eg: Akromaster. Whilst still shaped, its aerofoil is remarkably thinner and smaller overall than the Peacemaker's for only 50²in less area. Both ships end up weighing in pretty much the same, but IME the Peacemaker can carry an extra two ounces without a murmur because of its wing. Even accounting for the faster speed of the Akromaster, it doesn't make up sufficiently for the lack of section and area, the latter making it far more weight critical, with of course, the resultant increased radius of loop or higher 'g' and AoA in attempting to achieve an equivalent radius at its higher speed.

As best I recall, the Flite Streak Jnr's wing is notably smaller again than the Akromaster's at around the 220²in in area, pretty much just a fraction larger than the Mini-Peacemaker at 190-200²in (version dependent) both intended for an .09 or .10 on which IME they fly well. All are good flying designs, but those with the higher wing loadings quite weight critical if good performance is to be achieved.

Thanks for the replys.

The CG started right behind the solid balsa leading edge. I removed the landing gear and added lead to the tail to get it about halfway between the leading edge and the spar.

As for it being twitchy. In level flight, the slightest movement of the elevator will cause a fairly violent pitch change (more so down than up ). I thought that may have been due to the forward CG. It is not unflyable, but it is not very much fun to fly.

Yes, the Chipmunk is a great flyer. I changed mine to a built-up horizontal and elevator hoping to save some weight but ended up having to add weight to the tail anyway. Even with a light engine and doing a lot of carving from the motor rails I was not able to overcome that long nose!

thanks,
David

thanks again,

David

David,

Check that the centerline of the wing and stab are lined up correctly. If the stab is not in line with the wing it can cause a condition called "porpoising". Also check that the thrust line of the engine lines up with the wing and stab (just up and down, out thrust is OK).

George

Oh boy, am I sorry I didn't see this earlier. Your problems indicate that something is VERY, VERY, WRONG. My PM will do the entire pattern with Engines varying from a Modella .12D to Enya .15DII to Enya .15III to OS .15FP to Fox Schneurle .15 combat special. You simply can't go wrong with a PM. So, what's up? I have read this entire thread and all the advice is good. But do you have one of the NEW ENYA .15D's? Many of these were equipped by the factory with a BADLY UNDERSIZED VENTURI that limits the revs to well below 10,000 on an 8x6. This alarmed several early customers until they got wise to it. You must get Enya's bigger venturi insert in there if you have one of these. The weight of that engine with silencer is an issue but my PM tolerates the noseheaviness of the similar new Fox and silencer (turned a bit wide without ballasting) so you should be OK.
Nate Sturman
Gunma, Japan

Would this be the Nate Sturman who worked for a college in Japan and was teaching young folks to fly CL combat using Peacemakers and Smousens, and participated on Isky's board a few years ago?

George Bain

Yup, that's me! Still in Gunma, Japan, after a year+ each teaching in China and the USA. Still have the first Peacemaker I built over here, rebuilt and in pretty good shape. Several other ships have gone south...think I will try a Galaxy next (45" Guillows design) or another Smousen...I have the plan for that.
nate

Hello Nate,

Glad to see you participating on the boards again. One of the last discussiions I can remember you participating in was when OS started using the rear needle valves on th OS .15's. I think it was on FP's just before the LA's were introduced. May have only been in Japan...or I may remember the details incorrectly (imagine that.. ).

George

Have been reading this thread for some time now off and on and I must agree with a previous poster that all of the advice given is sound ....... but as one who has built and flown GMA Peacemakers (English Version) for many years I am a little mystified by the original complainants problem. All of the Peacemakers I have built have been built to the APS plan with the exception of modifying the fuselage construction to include a 1/8'' plywood crutch with the result that I may have added a little more weight to the original formula .... but not a lot ...... the balance point always comes out just about where Aldrich intended it. I have used Enya 15 and 19 glow engines and have always flown on 60' x .015 stranded lines and the models have been a delight to fly and will do whatever you ask of it. Many years ago we flew without mufflers but in recent times these are now a pre-requsite and even adding the stock Enya muffler to these engines I have not experienced any discomfort in the performance of these models. I use an 8x6 APC on the Enya 15 and a 9x6 on the 19 and of the two I much prefer the use of the 19. In conclusion I must say that this model is probably the best alround C/L model for general use and outright enjoyment and I built my first one nearly 50 years ago and I have not finished yet ............... It is also most gratifying to read reference to many R/C flyers who are desiring to get a handle on enjoyment in model aviation!.......................Keep Circulating!.

jonuck,