Jenny Craig - V - Lead Zeppelin.

LAST EDITED ON Jul-10-01 AT 08:12 AM (EST)

Gents,
In keeping with a recent thread on airframe/engine combo's and there flying weights, what's the heaviest combo you've ever put in the air and what was the performance like. Lighter is better, ..that's a given, but it takes us some time to develop the construction skills to get to the "light".

I'm interested in wing loading numbers, if you've got them and what might be the limits of good (read good as: "it got off the ground and flew the tank out without doing major damage to itself, or your arm") performance related to these numbers. Of course any other measurement would be good also.

As Leonard and Matt mention on their "Bar bell effect" tip, wing loading will not be relative to performance depending on where the weight is located, but still I'm curious. What's the largest load you've ever flown?

My Magnum is going to come in on the plump side I fear (scared to death:o)), ...I'm not gona say how plump until after it's airborne at least once. As my knowledge and construction techniques have/are changed/changing in 13years so has the ability to keep the weight down. This porker will be interesting to say the least.

Also: At what point does the power to weight ratio take a marked turn downward in performance. We say that a brick will fly given enough h.p., ...how much is to much? When do you give up and just hang the plane up and look at it?

As many others, I've never weighed any of my models as a young C/L flyer, (until now). We just built and flew as they came off the building board. Best glider was a Fox-35 (no muffler)/C.G. Shoestring Stunter as I remember. I always used the "engine out" glide ratio as kind of an indicator of weight and balance of the model.

So, "My name is Tony, and I haven't lost any weight this week:-(, ...I'm depressed:-(, ...... where's my Twinkies:-)?"

"Lighter is better" is NOT a given. Scott Riese had to add 5 ounces to one of his Cardinals to get it to turn properly. Admittedly Scott builds extremely light.
I have a Shark 45/ST60 that weighs a full 70 ounces. It won advanced at it's first contest. I've been reading about some 75 ounce + stunters with 4 strokes that reportedly fly very well. I'm trying to learn to build lighter, but personally I think proper alignment is much more important than weight, within reason, of course.
Nils

The worst one that I've ever flown is the appropriately named scratch job of mine: Lead Sled. It started out as "Miss LA" because it slightly resembled the full scale racer of the same name from the 30s.

After unnumbered crashes, the oft-epoxied and recovered (linoleum like) model weighed a bit north of 4 lbs. As in 65 ounces, let's say. Given circa 515 squares, this parses out to around 18 ounces/ft squared.

Heavy.

But you know what: It flew fairly well (past tense, because I trashed it last week). Line jerk (not me), and the dowels holding the oft-broken profile fuse broke in mid air. Interesting to see it fold up without assistance from terra firma.

It always glided pretty nicely when landing. Go figure.

Started out with an OS Max 30-S. As it became more porcine, it "graduated" to an OS 40 FP, and also two Greenhead (not at the same time) .45s.

Interesting subject.

I am flying a 70+ ounce machine of about 700 square inches.
Power is Stalker 61 RE with REV-UP 12-6 prop. It flies very well. Turns extremely sharp and is less affected by turbulence and wind in general.

Light might be nice, but stiffness is at least as important.
You do need a fat, efficient airfoil to cope with weigth.

I agree Paul, stiff is very important as well. My Shark has sheer webs & CF tow all the way across all 4 spars, plus .5 ounce CF over the center of the wing & is very stiff. I got carried away on this one.

I may help it a little with a needed refinish job. I made a bad decision & painted it black. I'll never do that again. It looks pretty good until it sits in the sun for a while, then a number of bad things start happening :/ I have to keep it covered as much as possible when it's not in the air. Major pita in the summer. I can sand a lot of excess weight off it & remove some material from inside the wing while I'm at it. good project for next winter. Maybe it will be a Great White Shark next time.

My newly rebuilt profile Cardinal/ST.46 still flys very well, even after extensive repairs involving fiberglass that I'm sure added several ounces to it's already porky 56. I haven't weighed it, but I wouldn't be surprised if it weighs 60 ounces now. It doesn't matter, It still flys just like it did, maybe better. It needs less tail weight this time.

Niles is right on EVERYTHING. I added 5oz at the cg of my first Cardinal to make it turn BETTER. It weighed 50 with a ST-51 from Tom Dixon in it. IT FLY'S WELL. However, after Paul Walker saw the plane fly he noticed the square's and rounds were all out of sink. He's best flying IMPACT weighs 64 oz and fly's with an OS-40 VF. HE's 55 oz with a PA-61 does not fly to he's standards.
I took out the 5oz of weight last year to try it again. I have learned to fly VERY TAIL HEAVEY. A Full INCH behind the CG. Your Question about HP there is no Subistute for HP. A light plane with out HP will not fly as you would like. Scott

Thanks fella's,
Sounds like there may still be hope for the "Sky Pig" nee "Magnum". Now just to get the thing finished and fly it.

I've never had a scale to weigh any of mine. I think they are generally on the heavy side, since I've never been good a hollowing blocks and often use Monokote or Ultracote.
But, they've always flown pretty well until I tried the new design I just finished. It won't climb at all. So far, I've added one ounce of weight to the tail. That didn't help much, so I am in the process of moving the leadouts forward and ready to add another 1/2 to 1 ounce to the tail. Much easier for me to add weight aft than to get rid of weight or shift weight up front. Unless you dipped the entire plane in epoxy, I wouldn't worry too much about weight. There comes a point in construction that there isn't much you can do about it except worry, which never seemed to help mine get any lighter.

Well fella's,
I've just read part of the most recent issue of Stunt News. In a somewhat related article Ferenc Zamolyi mentions weight gains in his quest for both retractable gear, throttle control, and the use of 4-Strokes. He states that the "Red Baron" test bed for the 4-S engines came in at near 85oz.'s with the Saito .80 up front, and R/C throttle related items. He states ....

" Pulling squares as hard as I could possible manage, there was never a sign of sagging, of sliding - it just banged a great tight corner."

He also states:

"I've come to an interesting conclusion about weight, ..it's not as important as you may think."

If we build heavier models and power them with enough h.p. to fly the load it would seem that state of trim again plays the more important roll (within reason). State of trim would also include the "alignment component during build" as Nils relates. There are numerous variables to consider here of course, but if wing area, airfoil choice, and power selection are kept within reasonable limits perhaps most designs can perform well at higher gross weights then we have thought. Interesting to me also, is the continued mention on the R/C front of the "awesome vertical performance of my Fazer/Something Extra/ Cap XYZ (place aircraft of choice here). These airframes come in typically heavier then many (all?) of our stunt ships, but manage what appears to be great vertical performance, ..something I believe is a need, or relates to C/L stunt. Yeah, ...moving the RPM of the engine around will obviously make a large difference in this performance envelope, but is there not a connection to be made between ready to fly weights of these "Fun Fly" R/C types, and our C/L stunt ships? In any respect I'll be pushing the weight envelope with this Magnum, it remains to be seen just how well or bad it performs. And you know what they say about over weight types: "If you want to look skinny, hang out with fatter people then yourself". My Magnum will be parking with the 747's on the ramp, so clear the way there you lite weights.

Tony "I can't believe I eat the whole thing" Bagley

"I feel good at this weight, ...really I do, ...honestly I do."

I am uncomfortable with the institutionalised quest for the featherlight stunter. I have the feeling that we are scaring off newcomers in the sport because they find themselves unable to build light-weigth.

There should be a clear message to the newcomers/ beginners in stunt: "A model that is considered 'heavy' can still be a wonderful flying airplane. It might perform as good or even better than the light weigth version".

I have the feeling that we discourage too many newcomers in focussing on light-weigth. Instead we should focus on proper matching engines to models.

E.g: A FOX 35 WITH muffler is probably not a good choice for a 50 ounce Nobler. This Nobler might be better off with an ST 46.
It will even be more heavy, but it will perform better!

No?

I've told the story before of my hefty Magnum, which was and still is a well appreciated gift. I flew it with a light case SuperTigre .56 It had very adaquate power for the weight. The builder put a Rabe rudder on this one, so I dont know if I can say for sure that it would perform the top of an hourglass at this heft as well without it or not. I learned the full pattern on this plane, and am tempted to put an engine back in it and see if it flys as well as I remember.
EricV

PS: Any word on the Nats so far????

I've been at both ends of the spectrum. I built an SV-11 that came in at about 52 oz with a PA.40 on pipe. Flew pretty well until I started messing with the engine (put in a PA.61). It flamed out and is dead now.

The current plane is 710sq (very high aspect ratio) and weighs about 68oz with Stalker .61RE on Smith/Werwage 60 size diamondback pipe with 12x4 3 blade bolly runing about about 11,000. Flies well in the wind. No weight problems I can see. It seems quite happy.

The worst was a 720sq (6 to 1 AR) plane that I used Imron on. Came it as an astonshing 87oz. (Yikes!) with an ST.60. It was a pig and noticably sank in turns and the hourglass was always an adventure, even in calm air. Heck, that thing needed wind to stay in the air. Sure was pretty though!

I suspect there is an "ideal" weight for a given design and powertrain. For instance, Paul Walker's Impact flies pretty much ideally at about 60 to 62oz. Paul has built lighter ones and heavier ones, but in the end, he tells me that the ones at about 60oz, straight, and stiff fly really well.