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It’s dark when I get home from work now which means it’s building season. I’m building a 565 Spacer from the original 1954 Model Airplane News plan. Perhaps strangely, one of the reasons I am building it is because people keep telling me what a terrible airplane it is and yet I look at it and it’s very similar to some of the designs that I like to fly like Jim Clem’s Okie Bird and Gil Morris’ Toothpicks. I’ve read pretty much everything that people have written about Spacers over the years and some people fly them right/right, but Sal Taibi designed it to fly right/left and that’s the way it’s going to go. I have a Fox .25 that Bob Mattes reworked and I am going to try to keep it to 25-26 ounces. And I am going to build the wings flat, against my better judgement which says I should have a little washout in each tip.
The other reason for building a Spacer is that I want to try skewing the wing about a half inch forward on the right tip to keep the right wing up in the climb and I figure that should also create drag to prevent it from going into a left spiral dive when the left rudder tab shoots it left when the motor cuts. That’s a problem with the Spacer, something I suspect wouldn’t be happening if Sal had made the pylon about an inch higher. It’s going to have 3/8 incidence as Sal designed it, about three degrees down and left thrust and 1/16 to 3/32 left rudder tab. So Dan Berry might want to hide under his truck when I bring it to the Nats next summer! (I sure wish I could figure out how to make pictures work on this forum!)
IMO, Sal shudda flew it Rt-Rt. When I see good Spacers flying it seems the best ones are going Rt-Rt…& living to fly again. 😉
If you balance it where the plans say and glide left, it spin in whenever the nose gets pointed down.
I don’t really understand why anyone would build a Spacer if they were going to fly it right/right. I’ve read all the material from Model Research Labs and others on doing it, but I don’t agree with it. There are much better airplanes that a person could build — designs that were meant to fly right/right. If Sal Taibi had wanted it to fly the Spacer right/right he would have put the fin on top of the fuselage which would make trimming a lot easier and avoid the six or so degrees left thrust that some people have in their right/right Spacers.
The underfin is used on models, like the Spacer and the other designs I mentioned, to help it through the right/left transition. Basically, the spiral prop wash pushes on the side of the fin and makes the airplane go hard right, which you solve with a lot of left tab, which also helps keep the tail down and makes the climb steeper, and a little left thrust. When the motor cuts, the prop wash disappears and the left tab fires the airplane to the left hopefully into a glide. But if it’s too fast and too heavy it will go into a left spiral dive. Reduce the wing incidence as many people do on the Spacer and it will be even more likely to do so.
The reality is that hundreds if not thousands of people have built Spacers over the years, balanced them where the plan says, flew them right/left as intended and they flew beautifully. But shorter motor runs and more powerful motors make this more difficult. So, as I mentioned, this is an experiment to see if I can solve the spiral dive problem by skewing the wing.
I have a SWAT that used to fly a beautiful right/left pattern until I gave it a boost in power, after which it would usually go into a spiral dive off the top of the climb. So, I re-trimmed it to go right/right, but it’s not happy doing so and only gets about two-thirds as high as it did when it went right/left. My experience is that models that are designed to fly right/left need to fly that way.Built one in ’62.
Re-kitted on the first flight with a spiral in to a concrete runway.
Too many pieces to pick up.
Same for engine.
Vowed then, “never again”.
I’ve heard that at Texas contests you are required to Yell “SPACER!” whenever you launch one.
Just for safety’s sake you see.
Cheers!I have built two A size 90% Spacers which is 486 sq.in., powered by pretty good K&B Greenhead .19’s. First one was built around 1987 and was an excellent flyer- of course it weighed 19ozs., had 4-5 degree left and down thrust, left rudder tab (3/32″x 3/8″x 1.5″long TE stock) and 66% CG and went right/left. Most times, it went as if on rails like it had VIT and I even flown it in A gas when too lazy to get out a “proper” A ship, once went as far as making the 7th max. This plane met it’s demise at the 1989 Lawrenceville USOC/Nats when very early in the morning the engine ran exceptionally good and as a result, the higher revs pulled the plane left under power and never really pulled out, doing a slow spiraling left death spin onto the runway, splat! Built another just like the first one. again right/left but this time moved the CG forward to 62%. This resulted in a safer spiraling right climb and the plane did well until the 2001 SAM Champs at Claremore, OK. It was a very hot day, around 100-105 degree and it did the first two maxes easily (Cat.II rules) but went out quite a ways on it’s second flight. I had to leave the meet for 4 hours to tend to business at work (Claremore was only 30 minutes from my office in Tulsa) and as a result, the plane sat out in the 100+ heat all that time. Finally made it back to field and located the model and proceeded to try to make the third flight. It zero’ed out, never lifting it’s right wing and plowed into the hard sun baked turf, completely totaling the plane. In looking over what was left of the plane, I noticed all the wing panels were flat. I believe the plane sitting out in the 100+ heat for 4 hours cause the tissue covering to loosen thereby making the right wing panel to lose all it’s wash-in and plane didn’t have a chance to get it’s nose up during that fateful flight.
I’m currently flying the Battle-Axe design in NOS and like it very well but at times, I have considered building another 90% A Spacer since it was a good flyer when plane is new. Main thing to watch for is keeping the wash-in in that right main panel which is very hard to do with the design having no upper spars to lock in the warps- have to dope/twist the wing to induce warps into each panels. If I built another Spacer, I would change the main lower spar to a I-beam type and also install a upper spar in the forward 1/3 of wing- keep everything else the same as far as thrust arrangements and CG location.
Good Luck!
Robert
Hi Robert,
It’s a relief to hear someone has been successful flying a Spacer right/left. After the doom and gloom comments I was thinking I should probably have kept this project a secret. My Okie Birds and Toothpicks all had/have wash-in the right panel and my inclination with the Spacer is to do the same, but everyone keeps telling me that would be suicidal so that’s why I decided to skew the right wing forward about half an inch at the tip which should create the same effect if I leave the wing flat. But, on the other hand, I wouId rather use wash-in. How much were you using? I am using polyspan for covering and that generally holds the warps pretty good.
Everybody seems to have a different opinion on the CG on the Spacer. Most people want to move it back, but I was talking to Al Heinrich at the SAM Champs last year and he said he moves it a quarter inch forward. I think I will start with the 62 percent you mention because that sounds pretty safe.
Regards, SimonSimon,
Both my A Spacers had 3/16″ wash-in tweaked into right wing panel, I suppose a 3/16″ x 3/4″x 2.5″ to 3″ long TE stock would be a decent substitute on a wing that has flat panel. My Spacers used Esaki tissue, Polyspan wasn’t available then but it should work just fine assuming you can get the covering tight and warps ironed into that right main panel- just check the warps at each meet before you fly the Spacer. It probably wasn’t necessary with the taper tips but my Spacers had 3/32″ wash-out in each tips. FYI, my A Spacer had 9″ main center wing chord and pylon had 1/4″ wing incidence- don’t know how that jibes up with the 3/8″ wing incidence in your 600 Spacer.
RobertHi Robert,
The orginal Spacer has a 10-inch cord, so the 3/8 incidence that Sal recommends would be a little more than what you had. I usually wash out the tips a little bit on every model as it helps the transition, so I will probably do that here too. I am just about finished the wing and I went with the original construction, although I did increase the size of the main spar in the main panels from 5/8×1/8 to 3/4×3/16, both to strengthen the wing and, well, the hobby shop had some nice pieces of 3/4×3/16.
All framed up and ready for covering. It came in at 23 ounces, the timer will add another 3/4 ounce and so, with covering, I should be pretty close or slightly over 25 ounces, which it needs to be with the Fox 25.The Spacer had its first test flights at Geneseo this weekend in a pretty windy test flying session. In the first couple of flights it went up left, so I had to reduce left thrust to three degrees and left rudder to 1/16, and then it started grooving pretty good — tight right spiral flipping over into a left glide when the engine cuts. Because of the wind I didn’t give it the full nine seconds, but it looks pretty safe. I set it up exactly as Robert suggested, 3/16 wash-in in the right panel, 1/8 washout in each tip and the balance at 62 percent. The incidence shown on the 1954 Model Airplane News plan turned out to be dead on. Initially, I had 1/16 balsa under the trailing edge of the stab but I had to take it out. It’s nice when things the way you expect, and very rare too. I still have to finish the tissue decorating. It’s been so cold and wet this spring it has been a struggle to get models covered out in the garage. This one just got finished the night before I left for Geneseo.
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