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The Spacer was designed by Sal Taibi as a favor for Bill baker at California Models who needed a new product. The rehash with side and down thrust was done by several flyers in Central California in the mid 1950s

Beware; This is one, big, serious airplane...

When you take this model out of the car the competition tends to fade away and retreat to a safe distance to watch this Top Dawg eat. This is a Real Huntin Dawg. You may not win every contest, but you should.

In dead air, eight minutes on a twenty second motor run is the mark all others can only aspire to. Build a good straight airplane, put a serious noisemaker on the nose, install the right windblower, and when you trim it out properly you will show them all how its done, consistently.

Congratulations, this big Spacer is the right choice. The Spacer is one of the very best designs for the Nostalgia events. This model is quick and easy to build and does not have any excess lumber in it. This is a clean low drag design with nothing complicated about the building or flying. The most outstanding characteristic of the Spacer design is that it is very easy to adjust and fly safely. When built as shown on the plans, Your Spacer will handle unbelievable amounts of power with no trim problems.

The decalage and thrust changes were developed in the 1954-55 era and the 435-inch version with a Torp .15 was on the FAI team. The Spacer on the drawings is contest legal. The Lucky Lindy is the only other design that matches the spacer in performance. But the Lucky Lindy is a high drag design with way too much lumber, and of course it is more difficult to adjust and fly. The Top Banana design is a close third but it comes with twice the work and its way more difficult to adjust.

The 1200-inch Spacer is a scaled up version of the 600-inch Spacer that was designed to use the Torp .19 engine. We doubled the wing area and is so doing we cubed the volume of the wing and the entire model. The old Torp .19 Spacers weighed about 24 ounces and this big one comes in easy at 60 ounces. This model operates at a Reynolds number that is about 280% of the old Spacer. These big Spacers have a truly outstanding climb and a MAGNIFICENT FLAT GLIDE.

Flying this model requires respect. This is a big, heavy airplane, (60 ounces equals 3-3/4 POUNDS). These things VTOs about like a locomotive, slow and majestic at the start and accelerating all the way up. They also tend to stop about like a locomotive. Are you sure you really want to catch 3-3/4 pounds moving at about 22 miles per hour? Sorta like playing catch with a bowling ball. This is a serious airplane; it does not really fit into the “toy airplane” category.

The current rules we usually fly under feature shorter motor runs and virtually require good clean VTOs in any wind conditions.

The 3 degrees of downthrust is just about right to pull the nose over for a clean VTO into a light wind. The 4 degrees of left thrust will keep things on track all the way up unless you built in a warp somewhere. The downthrust may need to be adjusted. On these big heavy airplanes the downthrust is largely determined by the; 1). Decalage 2). Flying weight. 3). Engine power. 4). Prop effficiency 5.) And of course the wind.

So, keep the weight down and the power up.

Climb is a function of weight and drag. Glide is a function of wing loading and drag. Drag increases on the square of the airspeed. And minimum airspeed increases on the cube of the weigh.
The only sensible response to the current rules is build models to weight and not a bit over weight, and of course put in all the horses you can find. Light weight, small size, minimum wing loading, & more power. It is the same compromise we have always faced when trying to improve the performance of our models.

Basically, we got a fresh set of 600-inch plans from Sal and added the thrust changes and the missing rib patterns. Note that I did not change the pylon incidence. However I did draw a new reference line showing where the wing platform should be. You will need to reduce the pylon incidence and move the balance point aft a chunk and two little bits.

Looking at the drawings, you will notice two types of lettering, this is so you can see where the changes are.

These plans were enlarged 141% of the 600-inch Spacer plans, so none of the wood sizes I called out will quite match the drawings.

Building instructions;

Build it like the drawings, keep it light, and straight, put in plenty of power and you will have a winner. I would suggest you omit the 3/16 square framework in the fuselage, just go with the heavier sheet wood in the fuselage. If you build the model per plans it will come out at about 55 ounces, which does not leave much room for adding unneeded tricks or fancy paint.

You must select your wood carefully or you will end up with a 75-oz lead sled that has absolutely no hope as a competitive airplane.

The only major revision you will need to consider is the incidence in the pylon. The plans show the original incidence setting. This does work fine, but it will produce a model that makes perhaps 10-15 turns under power. I build all of mine with only .300 incidence in the wing platform and sometimes trim some of that out during testing.

The absolute minimum incidence this model will safely fly with is .225 incidence in the wing platform with the stabilizer set at zero. Note that the plans show the bottom of the fuselage is a straight line and the stabilizer is set parallel to the bottom, so you can do all your measuring from the bottom of the fuselage to the wing platform.

If you do chose to build your model with the .300 incidence you will also need to move the balance point aft somewhat to achieve a good slow glide. I believe this change adds 100-200 feet to the climb and allows a slower glide, which all results in a model capable of dead air flights in the range of 7-1/2 – 8 min.

Do not get carried away and start adding still more wood. The only thing you need to do is make certain the main wing spar is real good solid 15 pound balsa wood. This is a well-proven design; you don’t need to add anything else. Do not use plywood for dihedral braces, as it is too brittle and will snap on a hard DT landing. Also note that we are sheeting the center of the wing both top and bottom, so relieve the ribs accordingly.

Use the Hayes engine mount with the square hole pattern to the firewall. Drill a couple of extra holes in this mount and you can mount the landing gear through the Hayes motor mount. By using two wheel collars with long screws you can stop the gear from rotating. With this Hayes mount you can then use thrust plate wedges of the same size and hole pattern to make easy thrust adjustments on the field. Don’t screw around with thrust washers. At the speed this model flys you don’t need the extra excitement that inconsistent thrust adjustments can add.

Make sure you get the pylon attached firmly to each former and at the rear of the pylon. Do not count on the glue joint at the fuselage top to retain the pylon, the fuselage top will flex and allow the wing incidence to change under high speed, and that’s not fun.

I like to cover my Spacers with the lightweight MRL .0015 Mylar on the flying surfaces. By using this .0015 Mylar on the flying surfaces I can easily control warps forever. Whatever you cover with, keep the bottom of the wing smooth and slick. Its OK to have a bit of tooth on the top surface of the wing. I prefer to cover the fuselage with MRL Polyester tissue, (Polyspan). I Use 3-4 coats of clear dope and a coat of Superpoxy.

Perhaps 80% of the lift is produced on the bottom surface of this wing. You should probably just forget all the rumors you learned in school about Bernoulli’s Law. It does not apply to this wing under these conditions. Way back in the 17th century Bernoulli proved only that the sum of static and dynamic pressures over a streamline shape always remains constant. He never even mentioned lift at low Reynolds numbers.

Incidentally, as a side note; By far the best method of cutting out ribs is with a 10” disk sander and a box type template that holds the stack of ribs up vertical to the disk. I constructed a special machine for this purpose, but now I think you would be better off using a 10” table saw with a disk in place of the blade. That little piece of metal that normally fits around the blade could be made of plywood and serve as part of the template stop system.

Engine, Props, Fuels;

The only really suitable engine for this big Spacer is the McCoy .60, Series 20. The Series 20 is the only one with a silver crankcase and red front and back plates. All of these series 20 engines will run pretty good.

Any engine that will not run good is generally because the rotor disk is loose on the backplate. You will need to reset it or spring load it with a small spring on the rotor pin outside the backplate. All McCoy .60s used a shim between the rotor and the backplate, this shim is about .0015 thick stainless steel. The early engines used a shim that was about .250 dia., the last engines produced used a much better shim that was the same dia as the rotor its self. This big shim was worth almost a 1,000 RPM.

The only other unusual trait with this engine is that it wears out piston rings. Just look in the ports at the rings, if you can see tool marks on the rings, the rings are in good shape. If the rings appear to be slick and well worn in, it means they are totally worn out and need to be replaced. I used to change rings on a regular basis, as it was good for about 3 – 5 mph on my C-L speed models. In those days it was a tornado 9 x 12 prop, 50 % nitro fuel and 16,500 RPM on the ground would yield 155 mph every time. When it dropped off to about 152, I could change rings and get it back up over 155 for a while longer. Fortunately piston rings are still available from Dick McCoy and others. If you run into bearing troubles, they are standard sizes and readily available at the bearing supply houses.

The big Dooling .61 produces a whole lot of noise and a lot of power but it must operate at a higher rpm range and in this case that means a smaller dia prop, generally no more than an 11 x 4 prop. For serious contest flying we need the prop disk dia and area more than we need the noise. There are no other legal .60 size engines that will pull this freight train.

I would recommend and strongly suggest you do nothing more than fix any problem areas with the engine and then just leave these engines stock. For 30 years we all tried to improve on the timing and no one ever did.

Fuel is an easy item for these engines. They will run well on anything with 25% to 50% nitro, but you must have at least 20% castor oil. I think the best all round fuel for this combination is 40% nitro, 20% castor oil and 40% alky, nothing else. If you simply must put in some of that cheap, colored, synthetic oil, be smart and maintain the 20% castor. You can reduce the alky content but not the castor. The only suitable synthetic oils I have ever tested all cost over $100 per gallon.

Props are a problem for this engine-model combination. There are very few props on the market to choose from. My favorite is the old Tornado 12 x 4 white polyester plastic. But it’s been about 30 years since these were last produced.

We need the 12 inch dia prop disk. Just remember that thrust increases on the cube of the dia. 12 inches cubed is a lot better than 11 inches cubed. You need to keep the RPM up around 13,000-14,000 to get the most out of these engines. The commonly available 12 x 6 is way too much prop for these engines and the 11 x 6 is about 30% less efficient. The correct prop for your model will likely be a wide, thin bladed 12 x 4 or a narrow thin bladed 12 x 5.

A 4-inch pitch prop at 14,000 RPM can produce a maximum airspeed of about 50-MPH, A 6-inch pitch prop at 14,000 RPM could produce a maximum airspeed of about 75-MPH. That 75-MPH would equal out to about 2000 feet of climb altitude. It simply is not going to happen with this model and this engine.

The efficient use of any 6-inch pitch prop is just a wet dream. You don’t need 2000 feet of climb, 1000 feet is plenty. Properly trimmed, this big Spacer will have a sink rate of about 2 feet per second. That’s a possible 500 seconds of glide time.

The only sure way to select the best prop is by flying and timing. Do not be influenced by the noise. I still have not found the best prop, but I’m still looking.

Suction type fuel systems work just fine with the McCoy. No pressure system will increase the McCoy’s RPM.

The Dooling seems to need a high-pressure system such as the pacifier or tubing type tanks, a metal tank on pressure does not help.

Flying, Adjusting, and Trimming.

The biggest advantage to the Spacer design is that they are very easy to adjust and very seldom crash. The low pylon and bottom rudder produces a model with a strong right turn under power. We can use this right turn tendency and adjust the model to perfection by sort of leaning on and counteracting this turn with left thrust which will produce an almost constant flight path.

From a VTO launch the Spacer can be adjusted so that the first 100 - 200 feet of climb are almost straight and will appear to have a bit of outside loop tendency. As the airspeed increases, the nose comes up and the right turn will take over so the model will complete one turn every 8 - 10 seconds of climb.

Warning;

Any Spacer that turns to the left under power is going to crash real soon. Any Spacer that climbs straight away all the way up with no right turn will not live for more than a few contests.

And while in the caution mode,

Never launch your Spacer in a Horizontal attitude, as it will dive into the ground within about 100 feet. This is because the wing and its incidence does not become effective until the model has some airspeed. The down thrust is effective anytime the engine is running good. I have personally tested this on several occasions and found it to be a true fact of life.

In order to get a good transition from climb to the glide mode, the model must have a right turn in the glide. The ideal glide circle for this size model appears to be around 800 feet in diameter. With a fast climb and this 800 foot right glide circle, your model will be able to perform a bit of a slip, and slide out into a slow glide with absolutely no loss or altitude.

Slow the glide down and you will get around a 7-min. flight on a 17-sec motor run. (7 for 17).

How it’s done;

This model is adjusted just like a big hand launch glider. Trim the power phase using the thrust adjustments and incidence shims, nothing else. It is not a good idea to use the rudder trim tab as in most cases this tab will screw up the transition to the glide. Trim the glide phase using ballast to move the CG, nothing else. Very simple. DO NOT change incidence to trim the glide. (see step 2).

Step one is make sure there are no warps in the flying surfaces. The stabilizer should be absolutely flat, no warps at all. The main panels of the wing should be flat, no warps, and no wash-in. The tip panels of the wing are going to have some washout due to their internal construction. Keep the tip washout to a minimum and make certain that both tips have the SAME amount of washout.

With these new covering materials you can remove any warps with a hot iron or hot air gun. I use a Monocote type iron and a glass top table as a flat surface so I can really get rid of the warps. I then know each wing panel is flat when it does not rock on the glass top surface. With the MRL .0015 Mylar, the warps will never return. With the Polyester tissue, (Polyspan) whether or not the warps return is largely a matter of your covering job and the amount of dope shrinkage that will occur. Warps are sort of an indication of your building skills. Be sure to plasticsize your dope. The best dope is Randolph’s nitrate and it’s available at the local airport for about $30 gal.

Sal Taibi’s
Magnificent 1200 inch

For Nostalgia Gas With a Honking McCoy .60 engine

Do not use wash-in on either of the main panels. On a high-speed model, such wash-in tends to straighten out the climb in the later stages and sometimes causes the model to attempt to loop over. Note that I said attempt, as this model should not have enough incidence to complete a loop.

Step two is to make certain the wing incidence is what you wanted it to be. First verify that the stabilizer is actually parallel to the bottom of the fuselage. Then measure from the bottom of the fuselage to the wing platform and make certain you have the .300 of incidence in the wing.

Step three is to glide test and trim for a reasonable glide with at least some indication of a right turn in the glide. Use stab tilt for a very wide turn, not much turn is required at this stage. Use ballast in the box under the stab, or on the engine motor mount lugs to trim for a slow nose high glide. DO NOT change the incidence in the wing or stab ! (see step 2)

Step four is short burst power test. I like to use a two-function timer and set the timer to pop the tail about one second after the engine cutoff. I like the Texas Timers, as they are good sturdy units.

Run your engine at a fast four cycle, just below the two-cycle break point. Engine run timer should be set at about 5 seconds. Point the nose straight into any breeze and with the nose up about 45 degrees. Launch with a GOOD SOLID PUSH so the model is flying as it leaves your hand. Your model will get about 100 feet of altitude and complete perhaps ½ of a turn to the right. At such low power settings it will appear that your model turns too much and does not have enough left thrust.

In the event that your model goes straight and does not demonstrate a positive right turn under power you have a problem. The best fix is to go back to step one and remove the warps like you were suppose to.

Step five is to increase the power setting on successive flights until you can go full power for the same 5 seconds motor run. Only when you are flying full power for a 5 sec motor run and it looks safe with a bit of right turn under power, then you can slowly increase the motor run times until you can go full power for 20-25 seconds.

At this stage the only adjustments you should be using are the stab incidence and the thrust line changes. Watch out for any looping over the top tendencies towards the end of the motor run, as this indicates a warped wing. This is the expected result of a tiny bit of washin in the right main panel.

Step six is to reset the DT so as to get a bit of glide time, about 20 sec of glide is enough to demonstrate a good transition to glide. This short glide time is also a safe way of checking to make certain there really is enough decalage between the wing and tail for a safe recovery. Decalage is the absolute angular difference between the wing and stab. A model of this size needs a minimum of about one-degree of decalage. One degree is equal to .0175 inch per inch of chord.

Step seven is better trimming of the climb phase. We both know the model is going up like crazy, but it can be improved.

VTO with full power and a 20-sec run. Carefully watch the climb all the way up to the top and watch the transition to glide.

If the model is completing less than three full turns, you should add a shim under the trailing edge of the stabilizer. (.010-. 015 is a reasonable shim for this purpose.). Try it again.

If the model is completing more than 5-6 turns you may want to open this up by putting a shim under the leading edge of the stabilizer or by increasing the downthrust by 1 degree. Whether to use the shim or the downthrust is determined by the first 100 feet after the VTO and the type of weather you will be flying in. You may end up with several shims under the leading edge and perhaps more downthrust.

These big Spacers are slow getting started and the downthrust is the prime method of adjusting the lift off phase. In order to VTO consistently in the wind you will need enough downthrust to nose the model over from the 85-90 degree launch position to about a 45 degree angle that permits the model to accelerate easily to the best climb speed. If you are not too concerned about VTOs in the wind or if the model is already nosing over a bit at launch, go ahead and put the shims under the leading edge.

At this point you should have a model that is doing 5-6 turns and getting about 1000 feet in 20 seconds. The recovery at the top should be a simple, slow down and slip, into a large right circle. If this is not the case with your model you will need to use a combination of thrust adjustments, stab incidence, and glide turn to complete the transition trimming.

Big Spacers that fail to VTO cleanly and get into the climb mode ASAP usually are suffering from a lock of thrust. First thing to Look at is the prop, too much pitch, too small a diameter or poor prop design are all climb killers. Second, make sure the fuel has at least 25% nitro and 20% castor oil. If you feel you are getting all you can from the engine and still not getting off cleanly, then you will need to increase the downthrust. Start with perhaps 1 degree more downthrust and about a .015 shim under the trailing edge of the stab. This of course will require removing tail ballast and retriming the glide. All in All it’s a lot better to build the model down to weight and put a good engine on the nose.

When I go test flying these models I always carry two of the one-degree shims and one of the two-degree shims. I like to use the plastic shims sold by Ernst Products. I cut them to the size of the motor mount and drill holes to match. These shims will then work for thrust adjustment in either direction and by stacking you can get up to four degrees.

..................... There is no substitute for horsepower. Make sure your engine fuel and prop are the best available.

Step eight is to trim the glide to go with that great climb. Still using the 20-second motor run, increase the DT time to about two minutes and watch the transition and glide circle to make certain all is safe. Reduce the motor run to about 10 seconds so the model will be low enough for you to actually be able to see the glide. Now remove or add ballast until you have a slow, flat, mushy glide, with a circle of from 400 feet to about 800 feet diameter. You are not allowed to go to any big contest with a glide circle any smaller than 400 feet diameter.

Glide circle diameter control is best accomplished with wing tip weight and, or stab tilt. The problem with stab tilt is that it does change the incidence a tiny bit and affects the power climb you just got finished trimming. The problem with wing tip weight is that you can only use an ounce or so before it begins to affect the VTO. This is due to having too much mass too far off center from the thrust line and the CG. But the wing tip weight generally helps the power to glide transition, stall recovery, and thermaling ability of the model.

If you have a model that’s wants to circle to the left, don’t fight it, let it circle left. Forcing an unwelcome glide turn or too tight a glide turn is a major reason for poor glide times with any duration model. There is something wrong with the model that insist on going to the left, but if everything else is perfect, let it go left. If you detect some other problems with the trim you should go back to fixing warps and making certain you actually built it straight.

Good glide trim is very important but it is always a compromise of some sort. A lot of the models I see at contest seem to be trying to glide sideways like a crooked walking dog. It requires considerable effort to get a good glide circle. If you want to be a regular contest winner you should learn how to trim your models. The best trimmed models usually win.

When you have the absolute best glide you can get, add a bit more ballast to the tail and slow the glide down a tiny bit more, remember that drag increases on the cube of the airspeed.

The best-trimmed model will win the contest.

One other little bit of advice; Most contest seem to go into overtime, with fly offs. The fly offs usually are conducted with progressively shorter motor runs. The way your model is adjusted it probably will not transition well with less than about a 10-sec motor run. At this point you can readjust your model with more incidence and more turn. But since it is flying perfectly I usually just leave the trim alone and make the short motor run flights by tipping the model over to about a 45-60 degree angle at launch. This allows the model to accelerate sooner. Frankly by the 7th or 8th fly off round, I'm usually tired of the whole affair and I just count on the other guys screwing up first. Anyone that beats me knows they have been in a real contest, and that makes them feel good.

The Winning Way

In Order to fly competitively you need good models, well trimmed, good fuel, good props, good engines, good luck, and contest flying experience picking good air. There is no magic; the thing that makes the big difference is the desire to win….

Decide why you are going to the contest.

The vast majority of Nostalgia flyers have decided they don’t need to win to have a good time. Put up a few good flights and set in the shade and talk of the good old days, that’s all they need for a successful contest.

Some of them appear to be getting fat and old at the same time. If you decide you want to win most of the time and be in the top three all of time, you must get your act together and be ready to win. You will never be a consistent winner until you are able to go to the contest fully prepared and fully expecting to win. When you are prepared to win, you deserve to win.

At this point you need to get serious about trimming those models out perfectly and flying them until you know how, and what to expect every time. You will need to either mix your own fuel or find some one who will mix it for you. You need good props, You need to get a good TAC and I think the best is the Futaba. You need to work on the engine problem until you have the best engines and you know when they are right. You need a place to test run engines. I have a small motorcycle trailer that I mount a test stand on and drive to an empty road by the local dump, not even the cows complain.

Don’t ever expect to do any test flying or check it out flying on the day of the contest. You simply must do all that before the contest. You must be able to take the model out of the car, put it together and put up the first official flight of the contest and know its going to be a max. You can not expect to win if you are not ready to win. This contest flying is a game of confidence, you gotta know you can do it every time !!!!!

The only way to get contest experience is to experience it on a regular basis. This is also where you learn about the good air, bad air thing. The good air, Bad air thing will be with us forever and ever, so learn about it. Experience is the only way you really learn very much about air, but there are some basics you should understand: For every bit of up air there has to be an equal amount of down air or sideways air. Don’t fly in down air. Down air can be as bad as 500 feet per min, which means even the best model will be back on the ground in a little over 2 min. Strong up air can be even worse because not only do you go out of sight in 2-3 min, you also have a major problem finding the model. Don’t fly into trash mover type thermals.

These Spacers glide well and also thermal better than most other models. You must be careful about launching into any strong thermals. Watch the other models and judge the thermal before you launch. These Spacers get a lot altitude on the motor run and will occasionally go out of sight overhead in less than 5 min. A few years ago one of my 200 inch Spacers went out of sight in 2 min, 13 sec on my first official flight of the contest. I was out of the contest and ready to go home by 8:30 AM that day. I had a 3-hour drive home to think about stupid thermals and blind timers.

In calm weather, sideways moving air means there is a serious thermal in the area, so pay attention. These Spacers get so high that you are seldom able to place the model into the thermal you feel at ground level, but look around you and if it is a large thermal, go for it. Be careful, if it was only a small sized thermal that already passed through, there is always the danger of going up into the hole of down air behind the thermal. Experience counts, watch what the other guys do, especially the local guys.

In windy weather about the only thing you can go by is the gust and the time between gust, but remember that your model is going to be about 1000 feet from where you are feeling the gust. The good news is that gust usually mean things are changing and the wind is going to die down or maybe get much worse and blow the contest out. You must decide to either fly right now or chance it by waiting for the calm. I always waited, Taibi never waited, Taibi usually won. In the contest where the wind did calm down I really cleaned up properly. The Internet has some good weather maps. Check them out before you go flying each and every time so you can gain experience with these maps.

In any kind of weather the very best indication of up-down air is the other models in the air.

Now we come to the real reason these Spacers are better than most of the other Nostalgia designs.

These new high-powered Spacers will easily make the max flight time with out the need for a thermal. All you need to do is be ready to win and avoid the down air.

Generally speaking in most parts of the world, early morning air is very stable with little up or down air. The air is normally quite buoyant until the sun starts the convection heating of the earth. This air is ideal for your Spacer, nothing to lose and much to gain. You can fly early when you are confident that your model can easily make the maxs with out a thermal. Fly early and fly often, make as many official flights as possible before the thermals break out.

The early thermals are generally mild and of a very large size at ground level. By watching your altitude and flight times you can judge the thermal conditions and know when to become very cautious about picking air.

Within a year you will be a serious threat in any contest. Within two years you should be winning or within the first three places at every contest you are ready to win.

The first step is to decide

"Why are you going

to the contest ?"

The final step is to know

exactly what you are doing.

Never, ever launch this model until you are absolutely certain in your own mind

that everything is perfect and the model is going to rack up another Max. Flight.

You must have confidence

We are also providing Spacer plans in the following sizes for Nostalgia gas contest.

145 sq. in. for Cox Tee Dee .020 engines

204 sq. in. for .049-.051 engines

435 sq. in. for .15 engines

500 sq. in. for .19-.201-.23 engines

608 sq. in. .29-.35 engines

1216 sq. in. for .60 engines.

Curt Stevens AMA 219

The older I get, The better I used to be.

November 1997