The Vertigo Revisited -- 10 years later!

One modeler's experience with this awesome aircraft designed by Tom Hunt.... This is a scratch builders dream project -- and Jaffray took 10 years to really get it right. Enjoy the saga of his exploration of the Vertigo.

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Introduction

On a normal day in July, 1994, I went to the mailbox and found the August 1994 issue of the Model Airplane News. On the cover was Tom Hunt and one of his Vertigo models, outbound on a vertical takeoff. I walked directly to the telephone (we didn't have cell phones to speak of then, or I would have called from the mailbox), and ordered the plans. I read the article. I studied the plans. I read the September 1994 issue follow-up article. Over and over and over. I am guessing now that at this point, I am not alone. This is without question one of the most incredible model aircraft ever designed and planned. Also without question, it is one of the most complex and demanding aircraft to build and fly successfully (which is why my aircraft waited for my abilities to catch up - like about eight years)!

In August, 2001, amidst periods of inactivity, I finally caught up with the short list of models that I wanted to build for my own personal use - except for one. The Vertigo. I had almost forgotten. Almost eight years to the day later, I jumped in with both feet, just like I wanted to back then at the mailbox. I made a wood list. I tuned up the foam saw. I had a friend in the aerospace machining industry, Ron, at Rock's Precision Machining, start making all of the parts that I could not. I burned the midnight oil, and by October, I was ready to cover the airframe. By November, I was ready for the parts that Ron was not quite finished with. By January, 2002, I was ready to fly. A few things remained to be sorted out, though. (I had a few "bright ideas" that worked, and a few that did not). In the end, the first of my Vertigo's is exactly as it was planned, except for the updated version of O.S.'s wonderful .46 ducted-fan engine, and some aluminum and carbon here and there.

In this article, I hope to share the experience and excitement I have had building and flying this masterpiece exactly as Mr. Hunt designed it, and to include those "bright ideas" and plans for future models, utilizing the latest available technology and construction techniques. I will include some flight briefing. I hope it pushes you fence-sitters right over the edge!

A Word About Pilot Skills

One thing that requires mentioning is the pilot's skills. This aircraft is capable of taking off and landing vertically, as well as hovering. The controls are set up to function like a helicopter in the hover mode, and an airplane in the flight mode. When you hit the nacelle-tilt switch, you have one, or the other. Ducted-fan experience would be somewhat helpful, but you need to know how to fly a helicopter to fly this model successfully! To hover is to hover is to hover! A nose-in vertical landing with this airplane is no place to learn how to hover! Great Planes "Realflight G2" is the simulator I purchased when I discovered this minor detail...pilot training! I trained diligently. I bought a .30 size heli and learned to fly that. You can get by with just the simulator if you practice, practice, practice. The G2 Harrier is as close as it gets to flying Vertigo, and it may even be a little tougher, lacking gyros to stabilize it. If you can fly a heli, Vertigo is a blast to fly!

Construction

I started with a wood order from Lone Star Balsa. While I waited for the wood to arrive, I started cutting foam. I used white Styrofoam for all of my parts. I used my own versions of the commercial foam cutters available. I cut 3 12" squares of the 3 thicknesses required for the nacelle, and tacked them together before cutting the nacelle to shape. Here's where the first "bright idea" came along. I thought that if I assembled the spar rings with the 1" foam layer and the pivot blocks in between them, I could cut the slots for the stator vanes in the foam at the right locations, and add them later. This way, I could build and sheet the nacelle without the stator assembly in the way. I sheeted the inside first, then cut the slots in the sheeting from the outside before I sheeted it. I was able to finish and glass the inside of the nacelle smooth and perfectly round. When that was done, I slid the tabs on the stator vane cores into the slots in the ring, and slid the stator hub into place in the middle. If all the parts are machined properly, it all goes together like a jigsaw puzzle. I centered the hub up and aligned everything using the engine, bolted to the hub, and a cut-out from the ring spar (a 1/8" plywood disc with a 1/4" hole in the center) bolted to the shaft. Then I glued the stator parts together. It worked like a charm! Next, I sheeted the stator vanes and added the leading edges and trim tabs.

This was well suited to the nacelle construction technique change, because the parts were self-aligning.

The nacelle turned out perfectly! I picked up an ounce, but gained tremendous strength and rigidity! I felt good about that hair-thickness of prop-to-duct clearance, too! I covered the outside of the nacelle with Monokote. All of the hover vanes, control rods and servos were added, and the nacelle was finished. I tried a variety of servos for the plane, and the ones that worked the best were the Hitec HS 85BB micros for the vanes, and the HS 81 micro for the throttle.

I wanted a solid connection between the can I had chosen, and the engine header. I wanted to reduce the space a silicone coupler would take up, and eliminate the chance for failure. A system of two collars, one between the header and the can, and one outside the can, was chosen. Three #2-56 screws through everything, tapped into the header hold it all together. This allowed the can to be opened up enough to get the bolt-through pressure fitting installed. Outlet holes were used at the end. It reduced the total noise to 104db.

I found the engine to run well on pressure, and poorly without it. I used Nylon fuel lines instead of aluminum, and used two lines through each spar tube. The exit for the tubes must be cut in the aft side of the spar tube, so as not to weaken it by cutting out the bottom right about where the load occurs.

You don't want to cut the fuel so close as to lose the engine as you settle in from twenty feet or so! I covered the openings for the fuel tanks with a translucent so I could monitor the fuel level.

I thought that since the radio was operating in V-tail mode to drive the hover vanes anyway, it would be a simple matter of "Y"-harnessing the tail surfaces to the vane controls. I could have elevator and two rudders with only two servos! The tail would undoubtedly be stronger and lighter as well! Great idea, butI made the control surfaces too big on the first try. The plane is already close to critical on the CG in forward flight, and this made it unpleasant, to say the least! And, any cross wind at the tail while in hover would cause a pitch-up as well as the weathervane effect, and this was too much for the gyros of choice at the time. (And the pilot! I decided to sort out hover later, and proceed to forward flight). After two flights with a conventional take-off and landing, I cut the tail off and returned it to the original design. The plane now flew much better, even with only one rudder (a must!).

I cut the lightening holes in the wings and booms as per the plans.( I will include them before covering next time.) The holes all occur aft of the CG. This allowed me to move the tilt battery (three 1500ma sub-c cells) from the nose pod to the hollow area in the balsa at the front of the boom opposite the tilt motor. This also allowed me to remove the lead from the wingtip that offset the tilt motor. I made an "extension cord" to make the modification easier; the next planes will be wired for the battery from the start. A thin fiberglass hatch covers the opening. I did not include any sort of charging jack for the tilt battery, so I had to remove the nose cone and plug in at the extension to charge.

I waxed the foam until the pores were pasted shut with mold release, and used two layers of 5oz glass crowsfoot cloth and epoxy resin. When this had cured, I sanded it smooth and fixed the thin spots before I cut the pod into the front and rear halves. I dissolved the foam out of the parts with Acetone. Next time, I'll cut the slot for the wing center section in the rear half before I remove the foam!

I spread waxed paper out on the glass table top and laid the cloth out on top of it. Then, I wet the cloth out liberally with epoxy resin, set the foam wing section right onto it, and weighted it evenly. This, when cured, offers much more strength than 1/32" balsa glassed with finishing cloth, and weighs the same or less. It looks kinda neat, too. I left it unpainted.

Equipment -- Then and Now

The first thing I encountered by waiting eight years to build Vertigo was the tremendous advances made in the engine and radio equipment available! The newer version of the O.S. .46 DF engine is no comparison to the older one. This engine rocks!!! The Futaba 8UAS transmitter has everything you need to run this model, and then some! And now there is the 9C! I am sure that there are other radios capable of flying this plane. All you really need is V-tail mixing and at least 3 P-mix functions, unless you want to replicate the A-tail.

The vanes and the A-tail move in opposition! To solve that problem, I used the V-tail mix to run the tail, assigned the hover vanes to channels 6,7,& 8, and slaved them to the flight controls. This way, I could select each vane's direction and amount of travel, and assign a common switch to enable the mix, or not, allowing them to be switched off for forward flight. This was good in theory, and worked just fine until one day, I left the ground on a VTO and the vanes had been accidentally switched off. Obviously, I had no control input to the vanes, but the flight surfaces were still operating. The gyros did not know or care that the mix had been switched off! Luckily for me, the plane was trimmed out well, and climbed out nice and level, making slow pirouettes on the way up. I waited until the plane turned into the wind at a safe altitude, and hit the tilt switch. Outbound transition was a non-event, and it was not until I landed safely that I found out what I had done! I deleted the option of switching off the vanes after that, but found that there are times that I would like them to go away, like at the bottom of a loop when the power is applied.

In the next planes, I am going to try a servo multiplier/driver, like the Futaba MSA-10, to individually link the gyros' gain adjustments, (which are not remotely operated now), to the tilt channel. I want to be able to set the gain individually, and make the gyros go away in forward flight. I could then re-assign the switch that enables and disables the P-mix. Then, the gyro's and the pilot's input to the vanes would be gone until the nacelle tilts down. And that brings us around to the most frustrating phase of this project...the gyros. This plane was published in 1994, and was researched for some time prior. The gyros on the market then were not the same as the units available today. Bottom line is, today, they are smarter. They think they are in a helicopter, though, and most of them will not work in this application! On the recommendation of the designer, I located and am using Arcamax gyros in this plane.

Arcamax is out of business, though, and their gyros are getting harder to find. E-bay and the other R/C forums are the best bet for finding them. Although they both work fine in my helicopter, the Futaba GY 240 and 401 will NOT work in this model! Heading hold is not used in any instance.

Flying

As I mentioned before, if you can fly a chopper, the VERTIGO IS A BLAST TO FLY!!! If you are not "chopper-friendly", you can get by with a crash course on a simulator to learn the fine art of hover. You must know how to hover something before attempting to fly this airplane!! That's half the fun.

My airplane came in at just over the designed weight of nine pounds. At that, VTO is limited to a day when the temperature is below 80F and the humidity below 70%, and this is at sea level. I doubt this plane would fly in Denver in the summer! Weight IS a critical issue.

Forward flight with this airplane is almost straightforward...(no pun), although power-on maneuvers are assisted (or hindered) by those pesky hover vanes that are still controlled by the gyros, but ignorant of the fact that the plane is NOT hovering! To add power and up-elevator at the bottom of a loop results in the whole plane being forced down. Close the throttle or hit the ground! Once you get used to their input being there, the problems they cause are minimal.

All of the servos and gizmos sticking out all over the plane equate to drag...lots of it! When you close the throttle, the plane slows down like it is towing a banner! To land conventionally requires throttle right up to the threshold.

Conventional take-off is almost automatic. The power is there, and climb-out is awesome! Rolls are easy enough if you stay off the rudder.

Outbound vertical is easier than it seems. On a cold day, I just taxi out to the middle of the runway, tilt the nacelle down, and jazz the throttle. You need to get the plane up off the runway as soon as possible, so it can level out. Then, climb like crazy to altitude, give the plane some forward stick to establish forward motion, and hit the tilt switch. Anytime the nacelle is tilted, the plane will pitch up. This is a manageable condition if you are ready for it. Allow the nose to level out before correcting the pitch-up. Make sure you're upwind! The plane will weathervane strongly. Yaw control is there, though. Transitions are a piece of cake when you get the hang of it! Inbound transition is a little more involved if you want to avoid the inherent loop that comes with the maneuver. I have developed a technique that works like a charm if you get past the fear of doing it. Most everyone I have talked with that has built and flown this aircraft has mentioned the loop inbound, including Mr. Hunt. He explains the reason for the pitch-up in the construction article, so I will not waste the space here. I looped the plane on it's first inbound, but, as advertised, at the bottom of the loop the plane is in stable hover and waiting for the next command. Not my nerves, however, and the quest began to tame this tiger!! I tried a couple of things. First, I tried gliding up to the stall and dropping the nose as I hit the switch. Boy, what an adventure!! Try this at altitude, if you must!

It is possible to approach hover like a car at a stop sign, but the odds of success are not good enough for me! A pitch-up always occurs, and to level out without the loop is very hard and not real pretty. So, I said to myself, "self....the pitch-up is not going to go away", and thought about how use it to advantage. Brainstorm!! Off to the flying field I went, armed with the solution to the problem!

This is how you do it... as you fly the pattern for landing, establish the altitude at which you wish to transition while on the downwind leg. Turn onto the base leg and reduce the power slowly to idle. As you turn onto final, roll into the turn slightly nose down. Hit the switch as you bank over, and let the pitch-up pull the plane through the turn, like you would with the elevator. Stay ready with forward stick as you roll out level onto final. The plane is now still flying forward on the wing, and the nacelle has completed the transition. All that is left to do is wait for the speed to bleed off, and gradually replace the wing's lift with the advancing throttle. This truly works like a charm! I did it again and again to confirm the technique, and jumped for joy at my success! This is how inbound should be!!

I have been flying my plane for a year now, and just overhauled the engine. I must say, I like it even better since I have had it all apart! New bearings, and piston and sleeve were needed. The speed at which this engine turns, and the fact that the intake is right in the sand, probably account for the loss of the chrome plating below the ports, but it ran well right up to the day I hauled it down. It runs like new now! I anticipated wearing it out in is airplane when I bought it, so I bought the spare parts then as well. It worked out to about half the cost of a new engine. I will be a little more careful about where I crank up and hover from now on, though!

I am using 15% Omega fuel, and have been happy so far with the performance. I am using an OS #5 glow plug at the moment (because the hobby shop was out of Mc Coy # 9's). It has two flights on it now, and seems to be hanging in there. I prefer the colder plug in the high-output engines. I have yet to experience an engine-out VTOL situation...I'm not sure that it's a survivable event. I hope I don't ever find out, and this is where duct-fan experience is helpful. Like a chopper, a duct-fan model needs meticulous care taken to ensure that the engine remains reliable throughout the entire flight, especially the landing! Vertigo requires a reliable engine to fly safely. Like I have said, I really like the O.S. engine. It has proven itself to be just that.

Eventually, I am going to have to replace this airplane. I have already begun to collect the parts for two more airplanes. (I intend to keep at least one of these flight-ready in my hangar from now on.) Improvements are the order of the day for the next models. I'm going to put them on a diet. I want my A-tail back. I know I can make that work now. I want to make those pesky hover vanes go away in forward flight, and I want to bury all the servos and the tilt motor.

I am ever so grateful to Tom Hunt for publishing this plane, and the plans for it. I have really enjoyed building and flying it, and the people I have met during the course of the project. They inspired this article!

In addition, I have become a helicopter pilot. (My friends will tell you that I did so kicking and screaming). That being said, I wish I had started it all sooner and missed less of the fun! So all of you fence-sitters out there, here's your push....GO FOR IT!!! I'm glad I did! I can't wait to fly it again!!!

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May 17, 2004, 07:35 AM
Random acts of Randomness
eparkflyer's Avatar
I saw someone fly one of these here in Florida a couple years ago... Very neat!
May 18, 2004, 10:53 AM
Mwahahahaha
Guinea_Pig's Avatar
im going to try a small electic VTOL very similar to that
May 18, 2004, 01:51 PM
Registered User
guinea pig what do you plan on using to power your electric version. i am very interested because i am considering somthing similar
May 20, 2004, 11:10 PM
Registered User
Jaffray's Avatar
Thread OP
Quote:
Originally Posted by eparkflyer
I saw someone fly one of these here in Florida a couple years ago... Very neat!

I would bet that it was my airplane you saw. Two years ago, there weren't any other Vertigos flying in FL.

Where were you?


Jaffray
May 21, 2004, 02:02 AM
Registered User
Thorleif's Avatar
I received my Vertigo plans one month ago, and is in the early construction phase. This will certainly be my most ambitious RC-project so far... Thanks to Jaffrays exellent construction article, as well as many good advices from him i hope i will succeed! I will think about substituting the nacelle tilt solution with a microcontroller based stepmotor solution. I think that will save some weight, and also reduce the complexity of this function, time will tell.. In addition, this solution it will give me variable nacelle speed, wich will be a very good thing. It will also be interesting if i could make some electronics to stop the nacelle vanes action in forward flight. I will post some pictures as the project is moving forward!
Last edited by Thorleif; May 21, 2004 at 02:16 AM.
May 21, 2004, 06:12 AM
Random acts of Randomness
eparkflyer's Avatar
Quote:
Originally Posted by Jaffray
I would bet that it was my airplane you saw. Two years ago, there weren't any other Vertigos flying in FL.

Where were you?


Jaffray

Yup... I wouldn't forget the name! It was at dunedin middle school, back when we used to fly there.
May 21, 2004, 04:42 PM
Mwahahahaha
Guinea_Pig's Avatar
Etec 3s2p on himax 2015 on GWS D gearbox 13X6.5 prop drawing 9 amps AUW of equipment including servos 300g or less thrust produced = around 800grams

should be doable



May 21, 2004, 04:48 PM
Random acts of Randomness
eparkflyer's Avatar
looks cool... but is that factoring in the gyros, a way to have the motor pod(?)
rotate, and the vanes behind the motor?
Last edited by eparkflyer; May 21, 2004 at 04:52 PM.
May 23, 2004, 06:15 AM
Mwahahahaha
Guinea_Pig's Avatar

Correct


that is not factoring in the gyros or vanes i couldn't be bothered to draw them in i will use vanes and a heading lock gyro to control the yaw but the only real complex thing is that pod part, i may just try constructing that pod and experiment with how much vane is needed to get a good counter torque rotation and off course see hom much thrust i loose
Jun 02, 2004, 08:50 PM
Random acts of Randomness
eparkflyer's Avatar
http://www.corpcomp.com/weeks1/Rig/Moter_moves.html

Check out how he moves his "motor" (ok.. its a turbine!).

This has got to be WAY better than using a motor/switch/batteries !!!
Sep 28, 2004, 08:38 PM
Registered User
Jaffray. W. Stephenson did an EXCELLENT job on the article of the Vertigo.. Would enjoy reading more about the "A" tail configuration and if there was an improvement over the model's handling.

I now have my plans for the Vertigo and this article has me excited and ready to build it. Have most of my components now, and will start building the fuse and wings in the next month or so..

Hopefully I can add to this article to keep Tom Hunts Vertigo alive! ...

Doug Crawford
AMA District II Webmaster
http://www.amadistrictii.org
Oct 25, 2004, 10:43 PM
Registered User
King_Ice_Flash's Avatar
I attempted to make a foamie vertigo VTOL out of the blue Dow foam, however, it was too heavy with all of the radio gear to work. I used one servo to tilt the motor, no gear drive. I was running a 12x6 GWS prop on a himax 2015 4100 with 3s E-Tec 1200 LIPOs. You could hover it at full throttle with a full battery, but it weighed about 17oz. I only used one gyro, on the yaw axis. On the next model, I am going to get rid of all of the ducting around the motor, go with a built up wing, and use two carbon rods for the tail booms. Hopefully this one works better than the last one. That was a lot of work to make something that didn't. Atleast it made for a nice fire
Oct 25, 2004, 10:49 PM
Random acts of Randomness
eparkflyer's Avatar
got any pics of it??

a more powerful lift motor and better battery and it should be able to be done these days!
Oct 26, 2004, 03:18 AM
Registered User
Thorleif's Avatar
Quote:
Originally Posted by King_Ice_Flash
I attempted to make a foamie vertigo VTOL out of the blue Dow foam, however, it was too heavy with all of the radio gear to work. I used one servo to tilt the motor, no gear drive. I was running a 12x6 GWS prop on a himax 2015 4100 with 3s E-Tec 1200 LIPOs. You could hover it at full throttle with a full battery, but it weighed about 17oz. I only used one gyro, on the yaw axis. On the next model, I am going to get rid of all of the ducting around the motor, go with a built up wing, and use two carbon rods for the tail booms. Hopefully this one works better than the last one. That was a lot of work to make something that didn't. Atleast it made for a nice fire
Any pictures of it (before the fire )? Just one gyro you say, why not three gyros, as in the original Hunt design, to get yaw pitch and roll stability? Im currently working on my Vertigo, based on the original design, added with the updates from Jaffray. I have still not decided wich gyros to select, any suggestions?

Thorleif


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