Hey... Somenzini spent a week here some 3 years ago. He took a Midwest's Extra plan and modified so it would be able to fly both pattern and 3D better. Finally built 1. Any one actually flying a Midwest Extra? I'm planning on put a ZDZ 80 twin fo better vertical performance. I've been looking for any other engines but this one has the best weight to power ratio. Any one suggestions on this? I fly at 2500 feet over sea level.

A Midwest Extra has an 80" wingspan and weighs about 15 lbs. You should get unlimited vertical with a DA50 or BME 50 and still keep the weight down. The 80 twin won't even fit in the cowl.

Even at 2500' a 50cc engine should give you unlimited performance. Mine was built stock and has great performance with a Brison 3.2.

You guys are killing me! Stick a Moki 1.8 or similar in there and call it a day. Are you looking for something that performs like a space shuttle or an aerobatics machine that doesn't have to be pointed up with the engine screaming in order to avoid falling from the sky?

I have some time on a Midwest Extra powered by a ZDZ 40 and weighs 17 lbs. What a dog. I would say that at no more than 16 lbs with a DA 50 would yeild a fantastic airplane. At 15.5 pounds and a Moki 2.10 it would perform even better but who wants to clean up that mess after flying?



Shawn

Anything much over 14 lbs is too much for that airplane if you want decent handling for precision aerobatics. Keeping it close to 13 lbs is ldeal. It's actually quiet capable of keeping up with much larger gas powered stuff, it just has to be kept to a reasonable weight. As far as the mess goes, yeah, goes with the territory I guess. I'll take the mess and shave the weight to get a better flying airplane.

Saw one today with a Brison 3.2. Looked like weight wasn't an issue.

I've built the MW Extra. 17 pounds. And I don't build heavy. I paid very careful attention to details and glue usage with this plane.

Somebody give me detailed instructions on how to build one at 13--15 pounds and I'll do it.

Building heavy is a lot harder to do than just adding heavy equipment. At 17 pounds, I would guess you used a large gasser with a slimline Pitts style muffler, aluminum spinner, CF prop. and nicads or nimh's instead of li-ions or lipos, and maybe even added a pilot and cockpit.
This plane can be built down to under 13 pounds if the cards are played right and you don't mind nitro...

OK, no servos in the tail for starters. All you need is a single elevator pushrod made into a Y at the exits, done the way that Pattern birds are frequently set up. So you make sure you have some form of rear bearing to keep it from moving side-to-side. It's a good idea to also have some lightweight guide in the mid-section to keep it from swaying about. The elevator servo can be something as little as a 4721, though I currently am using an Airtronics 94358. Something 120 oz-in or higher is needed. It is mounted on its side, exactly centered to keep the geometry right as it moves and to guarantee that the elevator halves movie equally (assuming everything else was done right with the horns etc). You can use a 1/4" spruce stick for the pushrod with 2-56 hardware or go CF, but you don't need a honking big, heavy arrowshaft if it supported well. Use 4-40 hardware if 2-56 makes you nervous, the weight isn't much different, but you lose some adjusting precision.

Rudder is pull-pull cables. Again, around a 120 oz-in servo is just enough, but better to go with something in the 140 to 200 oz-in range. Use a light tailwheel etc. I ended up lightening up the plywood frame for the fuselage, especially aft of the wing TE. How much, I don't remember, but it's overbuilt to begin with and you can trim the lightening holes larger to lose more weight back there. Throw away the ABS cowl and wheel pants and get something in a nice FG set. You can go CF on the landing gear, though I didn't. If you need to, you can drill some lightening holes in the center of the gear and gain back a little bit. I didn't have to. Mount the tank in the mid section, use a pump or pressure regulator system to get a reliable run if using glow. You don't need any extra hardware up front now that the tail end of the barbell has been slimmed down. The tail on mine was rebuilt using sheeted foam cores, since mine started life in 1996 or '97 and originally had the flat stab. Dick Hanson was cutting those cores at one point in time. Anyway, this is a lightweight replacement to the original design which was structurally inadequate without bracing wires or else beefing it up alot internally. As I understand it, the current MW kit has the stab constructed of wood ribs etc, which might be heavier than the foam tail I did. Not sure though, but the foam tail was considerably lighter than the original slab of wood. I'm sorry I can't recall the extra savings for each step, since it was 5 years ago when I did the retrofit.

The wing spar is overkill and can have lightening holes cut in the outer sections of the internal plywood joiner, i.e., outboard of the ribs that align with the fuselage sides. It's tempting to dump a bunch of epoxy in the spar box and make it heavier that way too, use enough to wet everything and keep it at that.

Try one of these on the elevator, I have wante to try one on a 27 percent.

http://www.centralhobbies.com/contro.../Bellcrnk.html

You are just adding weight back into the tail with that, at least partially defeating the purpose of moving the servos forward. I have one (new) you can have for half price if you still want to go this way though.

I also have one new and will not use it...

When I started in IMAC this was the plane of choice. I had one with a Moki 1.8 and it was 14 lb with dual el servos and a jumbo rudder servo on a pull pull. It was a excellent flying plane. The best one I ever saw was powered by a Saito 300 twin and it was just under 15 lb. Many IMAC pilots in the NC region remember that plane. It was flown in Advanced class by Dave Pinegar and dominated. All the gas powered ones I have seen were too heavy and suffered from vibrations.

I thought by elimnating a matchbox and a servo you would save a decent amount of weight, is the bellcrank that heavy?

A matchbox in a MW Extra? No channels mixes in the Tx maybe? Anyway, sure, there's a weight savings and all that, but the trick is to get all the weight you possibly can out of the tail. My original MW Extra configuration needed noseweight with a Moki 1.8 in the nose. The Moki is a fairly heavy engine, though not as bad as some of the gas engine choices I've seen being advocated. Moving the servos out of the tail and yes, eliminating one of them by going to a Y pushrod for elevator, was a big factor in the airplane losing weight. Getting something like 4.5 oz of servos and wire out of the tail and replacing it with about .25 oz of a pushrod meant that about 11 oz could come out of the nose. So the airplane kept about 2 oz of the servo weight moved from the tail, but lost more than 13 oz overall just by moving the servos. The rest of the weight reduction was by getting the tail feathers MUCH lighter through replacing the "slab sta"b with a foam core thing etc.

So to answer the question about the bellcrank, since it's much heavier than the Y pushrod arrangement, you will pay for it through weight in the nose needed to balance properly.

Sam, I remember Dave Pinegar and his Saito powered MW Extra as well. You are 100% right, back in the late 90's, the MW Extra was a fairly dominant design and in the right hands, it was hard to beat. I did reasonably well with mine, but I was still coming up to speed on things at the time and I was the limiting factor much more so than the airplane. The MW Extra helped me get 4th at the 98 Nats in Toledo in Advanced, ahead of several big gas planes, one of which was flown by a former Nats winner in Masters Pattern. The point is, it's a good design and if set up right, it can be competitive. I realize it's not going to be a top pick these days, but it's still a good airplane. Good enough for to have recently dusted mine off to get it back in the air for some relaxation this fall, now that the pattern contest season is over here in D1.

You make an interesting point.

I will pile on here and say that the jersey boy speaks the truth. An ounce saved out of the tail saves another 3 oz more or less (often more) out of the nose, for a total savings of 4 oz out of the all-up weight.

As for the MK bellcrank, I got two of them a couple years back, just to see what all the jabber was about. I put one in a plane that needed weight in the tail, and in that application it worked OK, but the other one still sits in its package. Go to the same Central Hobbies website and look up their Dual Elevator Pushrod System (somewhere in Technical Tips). I've used variations of that system on the last few planes I've done. It is a great weight saver, and gives very precise control with a single side-mounted elevator servo

10/4

I have the DEPS hardware and will use it eventually. My advice, plan ahead. I tried to build the balsa ladder and make it work in a Temptation I was building, but since I had not planned for DEPS to begin with, the exit engles at the rear were too extreme and they were binding. Had I planned for DEPS from the start, obviously I would have had the hard points in the right place to make the exit run correct.

Here's something else I intend to try and it is being used with very great success by a top local Pattern flyer (and I do mean TOP). You may think this is crazy at first, but if you use the Sullivan CF "nyrod" style pushrods, they work very well. One to each elevator halve, lashed together up front by the servo, ALA the DEPS method. Since the sliding insert is a different material than the classic Nyrod and made of some kind of CF impregnated plastic, it does not change length in any noticeable way, even over extreme temperature ranges. It's a lightweight solution, just needs to be supported properly so it doesn't flex around. I have used them on throttle on a number of big gas IMAC things (the usual suspects, a fleet of 40% Carden's etc) and they work extremely well. Believe me, if they were changing length with temperature, I would have noticed a change in the low end response of the DA's I was using. They could definitely handle the elevator job in something the size of the MW Extra, which is only slightly larger than the 2M Pattern stuff that our local guys is using them in. Probably the easiest way to get the job done, maybe even the best way.

I have the MK bellcrank in my Panacea. It does work great and is positive. Just wonder why anybody didn't make one similar out of a lighter material

What is DEPS?

Dual Elevator Pushrod System. It's a pair of solid carbon fiber rods that are run through telfon tube guides. They get connected together at the servo end and exit the fuselage separately for each elevator half. It's supposed to be a great solution, but it requires careful planning and takes a bit of extra work to built a lightweight supporting structure to keep the guides stationary all the way back to the elevator.