CAUTION

A Remote Control (RC) model aircraft is not a toy. It is a flying model that functions much like a full size airplane. If you do not assemble and operate model aircraft properly you can cause injury to yourself and others and damage property. DO NOT FLY a model aircraft unless you are qualified.

You are ultimately responsible for the mechanical, aeronautical and electrical integrity of any model you fly and all of the components that make up the model including but not limited to the airframe itself, control surfaces, hinges, linkages, covering, engine, motor, radio, servos, switches, wiring, battery and parts. Check all components before and after each flight. It is essential that you act with the clear understanding that you are solely responsible for all aspects of the model at all times. DO NOT FLY until it is right.  

AVOIDING 90% of PROBLEMS that can arise:  

1. READ THE CAUTION ABOVE & READ THE LIABILITY DISCLAIMER.You are responsible for all aspects of any model you fly. You're It!
2. READ ALL DOCUMENTATION before doing anything else! 
3. INSPECT CAREFULLY immediately upon arrival!.
4. RETAIN ALL PACKAGING until the checkout is complete! If you need to return anything you must have all of the original packaging.
5. READ & LOOK! At everything! Do it once & then do it again.
6. REMEMBER WHAT "ARF" STANDS FOR. ARF means ALMOST Ready to Fly with an emphasis on ALMOST! Some assembly and modeling skills are required.
7. ALLOW ENOUGH TIME to enjoy the assembly process! Rushing into a 6 hour job with 3 hours to spare simply will not work. This is a Hobby... take your time.
8. DRY FIT & TEST ASSEMBLE EVERYTHING before you glue anything!
9. USE 30 MINUTE EPOXY when joining wings & installing stabilizers and other structural components but only after you have dry fitted and test assembled the components without glue! Once parts are glued together they cannot be unglued and they cannot be returned or replaced without charge.
10. PLAN AHEAD! BE CAREFUL! If you get into trouble, DON'T PANIC. Review everything again, talk it over with an experienced modeler and if still in difficulty consult our Support Services.
11. TEST TEST!!! TUG TUG TUG!!! EVERYTHING... BEFORE & AFTER EACH FLIGHT! Your model may have been largely pre-constructed and may have pre-installed control rods, hinges, control surfaces and many other essential components. Hinges may have been pinned after they have been installed. However, you must double check every control surface and component before and after each flight. You and only you are responsible for the integrity of all components and the integrity of the model itself. Check everything before and after each flight. Tug on control surfaces, control rods, mounting bolts, T-nuts, mounting plates... tug on everything!
12. DO NOT OVER TIGHTEN WING BOLTS or other fasteners. You want bolts and nuts snugly tight and if metal you can use a medium grade thread locker such as Pacer Z42 to help them stay tight. Fasteners must be snug and secure. However a model airplane is not a farm tractor or a garbage compactor. You do not need a pipe wrench or an electric drill to tighten up wing bolts or any other fastener. Leave your plumbing and power tools at home.. hand tools only and go easy on the torque... snug and secure... not stripped or torqued until they squeak or break.  Wing bolts can take tremendous torque before breaking... but when you over tighten them or use an electric screw driver on a set of wing bolts, long before the bolts break you can fracture the fuselage, crack the mounting blocks or pull the heads of the bolts through the wing... these problems have a nasty habit of revealing themselves when you least expect the wing to fall off!
13. DO NOT OVERPOWER ANY MODEL! Stay within the recommended power range for the model. If you overpower the model you run a high risk of structural failure that will lead to loss of control and a subsequent crash that will destroy the model and may cause injury and/or property damage.
14. ASSUME NOTHING! Remember the old yarn about what happens when you ASS-U-ME something. Check everything repeatedly and frequently and DO NOT FLY any model unless you are satisfied that everything is in good working order.

Question: Is there a cross reference between Engines such as Magnum and Thunder Tiger?

Answer: Yes, please see the attached cross reference information.

Note: Many different parts are made by a relatively small number of manufacturers and may appear in various brands of engines. The attached cross references are reasonably accurate but there is no guarantee that the parts fit your particular engine. Only a careful purchase followed by a trial installation will tell you for sure that a part fits.

Note 2: ASP, Magnum and GMS engines MAY MAY MAY use some of these parts as well. See caution note above.  

Question: How much deflection should I use for my Flaps? Can I overdo it?

Answer: We recommend using no more than 50% of the maximim deflection that the flap is capable of. Any more than that will likely due more harm than good.

Better Answer: If you overdo the flap deflection beyond 50% of the maximum deflection that the flap is capable of, you will get little additional flap effect but will substantially increase the drag and possibly make the model unstable. There is also a reduction in the effectiveness of the vertical stabilizer and the rudder when as flap deflection is increased. This loss of effectiveness can reduce the ability to counteract and control Yaw making it particuarly important to ensure that both flaps are deployed to the same degree at all times. Differential (non-equal) flap deflection can result in a crash due to roll and pitch changes that can be very difficult to overcome and control.

We suggest phasing in the amount of flap deflection, starting with very little and working up to the 50% max noted above. At each step, test your control over Yaw (using the rudder) and Roll (using the ailerons). If you can't maintain control over Yaw and/or Roll or the model is Pitching suddenly up or down, back off on the amount of flap deflection.

Question: What are Flaperons and what is meant by the term Flaperon Ready?

Answer: The term Flaperons is used to describe Ailerons that can act as Ailerons AND act as Flaps. When we design Ailerons so that they can or must use two servos the model is Flaperon Ready.

The Flaperons in a Flaperon Ready model are not mandatory but we have designed the model so that the Ailerons can be activated as Flaperons if you use two servos for the ailerons and a computer radio.

Better Answer: Flaps are generally used for take offs and landings only. They hang down from the back edge of the wing and increase the lift of the wing enabling the model to take off and land at slower speeds. Landing at slower speeds can make landing a little easier on the nerves. Flaps go down only.

Ailerons are used all the time in flight. Ailerons go up and down.

By using two servos and a computer radio it is possible to use an Aileron like a Flap while still using it as an Aileron. This is called a Flaperon.

When we manufacture a model we always include Ailerons. When we design Ailerons so that they can or must use two servos the model is Flaperon Ready.

To take advantage of Flaperons in a Flaperon Ready model, you must use two servos for the Ailerons and must have a computer radio.

For information regarding Flaperon Deflection please see the following article,

Question: How much deflection should I use for my Flaperons? Can I overdo it?

Answer: Use 50-65% of the maximim aileron deflection. Any more than that will substantially reduce the effectiveness of your ailerons.

Better Answer: If you overdo the flaperon deflection (i.e. when using the ailerons as Flaps) beyond 50-65% of the maximum aileron deflection you will get little additional flap effect but will substantially reduce the effectiveness of the ailerons (i.e. ability to roll left or roll right).

When over deployed as a flap, the aileron cannot move further down as an aileron. The other aileron can move up so you end up with half the roll effect much like that you would experience with having only one aileron. In addition to the weaker  more sluggish roll effect of a single aileron you will have yaw induced by the differential in deflection between one aileron and the other.

Question: How much deflection should I use for my Flaperons? Can I overdo it?

Answer: Use 50-65% of the maximim aileron deflection. Any more than that will substantially reduce the effectiveness of your ailerons.

Better Answer: If you overdo the flaperon deflection (i.e. when using the ailerons as Flaps) beyond 50-65% of the maximum aileron deflection you will get little additional flap effect but will substantially reduce the effectiveness of the ailerons (i.e. ability to roll left or roll right).

When over deployed as a flap, the aileron cannot move further down as an aileron. The other aileron can move up so you end up with half the roll effect much like that you would experience with having only one aileron. In addition to the weaker  more sluggish roll effect of a single aileron you will have yaw induced by the differential in deflection between one aileron and the other.

Question: I've heard some horror stories about snap rolls and seen some spectacular sudden crashes that the pilot stated were caused by a snap roll. What can I do to prevent this happening to me? Is the risk manageable?

Answer: Yes the risk is manageable. Keep your airspeed up and limit the amount of elevator throw at lower air speeds. Be aware that low wing aerobatic models with smaller horizontal stabilizers generally will snap roll more easily than others.

Better Answer: First of all it is important to say what we mean by the term "snap roll". It is frequently misused and it is not always a bad thing. A snap roll is like a roll induced by using the ailerons but it occurs with little or no warning, is usually extreme or violent and usually does not involve using the ailerons. Snap rolls are often messier... they are not a clean aileron induced roll and often look like the rudder is being put into play as well. This scares the dickens out of pilots who have become used to seeing an airplane roll only when it is asked to do so by deflecting the ailerons.

In fact most aerobatic aircraft use snap rolls as part of their repertoire of maneuvers. So one way to reduce but not eliminate the probability of snap rolls is to stay away from aerobatic models! Unfortunately this approach takes a heck of a lot of fun out of one whole category of RC Flying!

Rather than give up on aerobatic models, manage the risk with the following tips:

1) Watch your Altitude: Snap rolls are not dangerous themselves unless they are so violent that they tear the airframe apart. This can happen in lightweight 3D type models but other than that most model airframes are built to withstand a snap roll. It's not the snap roll that wrecks most models... it's impacting the ground that causes the problem! Granite Congestus is hard stuff! Altitude is everything. If you are going to experiment, do so with lots of air between the model and the ground.

2) Watch your Air Speed: Many unexpected snap rolls are caused by insufficient air speed. Keep your flying speed up. If in doubt, a bit too much air speed is better than too little.

3) Watch your Angle of Attack: All wings have an angle of attack beyond which they will not fly. If you force a wing beyond it's critical angle of attack, it stops flying and your model becomes a brick.

4) Watch your Elevator Throw: This is probably the most critical single thing you can do. Too much elevator throw rapidly and often uncontrollably increases the angle of attack and reduces your air speed. High angles of attack and reduced air speeds are precursors for the almost immediate onset of a snap roll.

5) Watch your Landings and Take Offs: Things gang up on you when you are near the ground. Your altitude is low, your air speed is low, your angle of attack is higher (particularly when landing... slowing down, preliminary flair setting up) and you are nervous on the sticks with a tendency to overcompensate on elevator every time the model takes a bit of a lurch downward.

6) If your radio supports dual rates, set up dual rates for the elevator and limit the throws at the low rate to not more than 65% of full aileron deflection and use the low rates during take offs and particularly during landing. You might want to experiment with exponential as well to reduce sensitivity of the servos to movements of the sticks near center.

Remember that Snap Rolls can be fun if you've got altitude and time on your side. Stay out of low altitude situations when one or more of the other contributing factors start to come into play and you will be managing the risk of a snap roll induced crash!.

Question: How much deflection should I use for my Speed Brakes? Can I overdo it?

Question: What is a good second or third model after I have soloed on a Trainer?

Answer: Probably the best choice would be to move from the high wing flat bottom airfoil type of trainer you learned on to a high wing model with a semi-symmetrical wing.

Better Answer: It really depends on many things and there are lots opinions to listen to on this. We recommend that your second model be a high wing model with a semi-symmetrical wing and trike landing gear. You could go to a high wing semi-symmetrical tail dragger if you are flying from long grass or a rough field.

If you want to make a bit of a leap, move directly from your high wing trainer with a flat bottom wing to a semi-symmetrical low wing model with trike gear. We do not recommend going to a low wing tail dragger when you move to your first low wing model. Too much change all at once. A low wing model requires a different set of flying skills and a tail dragger can be a bit challenging when it comes to ground handling. Best to tackle your challenges one at a time.

Ideally we recommend the following sequence of VMAR models...

1. First Model - High Wing, Flat Bottom Wing, Trike Gear, at least 60 inch wing span.
   • Apache or Discovery or Challenger
2. Second Model - High Wing, Semi-Symmetrical Wing, Trike Gear, at least 60 inch wing span.
   • Stinger or Hornet
3. Third Model - Low Wing, Semi-Symmetrical Wing, Trike Gear, at least 60 inch wing span.
   • Escape or RamRod
   • Subaru (semiscale model of a real aircraft... has all the characteristics of a good low wing trainer along with semiscale appearance of a good looking aircraft)

Question: Does the factory provide NACA designations for the wings used in VMAR models?

Answer: VMAR models are known world wide for their great flying characteristics. One of the keys to this is the unique wing design. As such, the factory considers this information proprietary.

General airfoil types are described in our specifications and the following article includes tips on how to determine the airfoil type.

Question: How can I tell what airfoil type is used on my model?

Answer: This is usually listed in the specifications for the model but if you can't locate the specs, not to worry. There is an easy way to determine the general type:

1. Check the wing root (or wing tip if the root is not accessible).
2. Draw a line from the leading edge to the trailing edge (or align one edge of low tack masking tape if you don't want to leave any marks later on).
3. At the Thickest part of the wing, measure the distance above the line to the top skin of the wing and measure the distance below the line to the bottom skin of the wing.
1. If the line is coincident with the bottom of the wing, the wing is a Flat Bottom Wing (also often referred to as a "Clark Y" wing)
2. If the distance above the line is greater than the distance below the line, the airfoil is Semi-Symmetrical
3. If the distance above the line is the same as the distance below the line, the airfoil is Symmetrical

Question: How can I tell what airfoil type is used on my model?

Answer: This is usually listed in the specifications for the model but if you can't locate the specs, not to worry. There is an easy way to determine the general type:

1. Check the wing root (or wing tip if the root is not accessible).
2. Draw a line from the leading edge to the trailing edge (or align one edge of low tack masking tape if you don't want to leave any marks later on).
3. At the Thickest part of the wing, measure the distance above the line to the top skin of the wing and measure the distance below the line to the bottom skin of the wing.
1. If the line is coincident with the bottom of the wing, the wing is a Flat Bottom Wing (also often referred to as a "Clark Y" wing)
2. If the distance above the line is greater than the distance below the line, the airfoil is Semi-Symmetrical
3. If the distance above the line is the same as the distance below the line, the airfoil is Symmetrical