Mac McGarrigle's Lifting Body
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My Rocket Powered Lifting Body Models

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RLBV IA Radio Controlled

This model is a radio controlled X-33 (actually a combination of X-33 and HL-10) that I flew together with Kevin Creamer at NARAM 39 in Phoenix, Arizona.  It was powered by an Areotech RMS-RC 32/60-100. 

From this flight I won a trophy for the 'Most Spectacular Flight'.  This surprised me a lot as I thought that there was more deserving models (like a full sized Patriot missile) at this great event.  Thanks again for the recognition. 

This lifting body model construction utilized a balsa wood bulkhead and construction paper that weighed in at 12 oz.  You would be surprised what you can do with simple materials!!   It also flew to about 350 to 400 feet, which was more than I was expecting.  

The transmitter was a Futaba T6XA computer transmitter configured to support elevon flap mixing.  It had a 150 mA battery pack and only 2 TS-50 servos. 

During boost the RLBV IA did strip a servo during one flight so I changed the configuration of the motor pod to include fins to improve boost stability (Kevin's idea) and not needing to use R/C during the boost.  This is a big lessons learned.

You can see that this model has inboard control surfaces mounted on the body.  This is the last model that will have this configuration.  The problem is that the control surfaces can only act in one direction.  The way I compensated for this was to design it so that the line of thrust passes through the Center of Gravity.  This was so that the control surfaces movement was not needed in both directions (up and downward movement) for the boost.  Otherwise I would have needed 4 control surfaces similar to the real HL-10.

HL-10 Free Flight Click on Photos...

This is a free flight lifting body model similar to the HL-10 except that it has wing stubs angled at 45 degrees and that are larger than any before.   I built this model in the years since NARAM-39 and is an example of the newer design but uses older construction methods.  It is powered by an Estes D12-3 and flies really well.   

Dimensions : 18 inches long, 10 inches wide at rear and 4 inches at the widest point.  It has a 11oz take-off weight with the motor mount weighing in at 4 oz that ejects.  It has a balsa bulkhead with foam board ribs covered with construction paper.  The covering is a low temperature MonoKote to make it waterproof.  When the motor mount ejects it releases the two control surfaces to bring the nose up.  It comes in at about a 15 degree nose up and the Cg is set at about 45%.  I am very happy with the flying characteristics of this model.

This was the first model I made using outboard control surfaces.  This allowed me to also make the shape of the lifting body with minimal base drag, which increases the L/D ratio a little, making it glide better.  The released control surfaces also hit against the fins as a mechanical stop so I could control the exact angle the control surfaces raise (about 30 degrees) during glide configuration.

Note the fin at the bottom of the lifting body.  This fin is carried by the motor pod along with the launch lug and ejected at apogee.  The extra fin gives the model additional boost stability and on ejection looses the additional weight.  If the fin was not removed during the end of boost it would probability damage the lifting body during landing (a.k.a. "Six Million Dollar Man" opening sequence).

HL-10 Free Flight  Click on Photos...

This was the first of the prior versions of lifting body designs but still had inboard elevons.  It is the basic free-flight design, however, has a motor pod which, upon ejection, releases the inboard elevons to bring the lifting body into the gliding configuration.  The active control surfaces allowed the Cg to be moved further forward allowing for better pitch stability at gliding time.  It still required additional weight for boost stability but that was contained in the motor mount and was removed from the body during gliding mode. 

I designed the lifting body with wing stubs that had zero dihedral.  Apart from that it resembles closely the shape of the HL-10 within the limitations of the construction materials.  It is covered with silver MonoKote (thanks to my buddy Alex Seltsikas) and did have markings to make it look like a X-24A.  After long years of storage I am in the process of cleaning it up and redoing the markings to make it look like a HL-10.

HL-20 Free Flight  Click on Photos...

I built this to take with me to NARAM 39.  It is a free flight version with motor mounts similar to the HL-10 but with the additional fins for boost stability.  I narrowed the body depth to about 3" which greatly reduced drag during the boost so it flew a lot higher than the other models. 

This is one of the better flying models although I wished I had made the wings fins bigger.  I have a theory that the longer fins (at a 15 degree angle) act like another aerofoil and produces it's own lift and increases the overall lift coefficient.  I was thinking one of these days I will add fins with a symmetrical aerofoil to test it out.  In the meantime, I will use longer fins on all my models going forward.

I crashed this model on the last day of NARAM 39 during takeoff.  There was a light wind blowing but it was enough force to make the model unstable during takeoff.  The lesson learned here is that 'If the wind is strong enough to fly a kite then do that instead'.  Boost stability is an issue with lifting bodies.

RLBV 1B Free Flight  Click on Photos...

This is similar in construction to the X-33 that I took to NARAM 39 except being more like a true HL-10 aerofoil shape, except minimal base drag, and outboard control surfaces that move up and down.  It was an R/C version but I am in the process of changing it into a free flight version as I needed the R/C equipment for the next generation models.  This model is 24" long and 11 " wide (at the base), weighed in at 12 oz., and will be powered by an Estes E series rocket engine. 

The style nearly duplicates the HL-10 except for the longer and wider fins.  This is a balsa bulkhead, foam board, and construction paper model and is the last of such construction (for now anyway).  I am happy how this model has turned out based on the limits of the method of construction.   However it has taken me 4 times as long to build it than previous versions.  This is because more work was required to create a better aerofoil to improve the aerodynamics compared to the HL-20 mentioned above.  It was also difficult to figure out the exact aerofoil shape as this was before I discovered CompuFoil3D, aerofoil design software.

I am going to change the size of the elevons as I think I might have made them too small.  I have not flown this model yet but I think it will fly well.  I will have it ready for the first dry launch day at the NASA Houston Rocket Club launch at the Johnson Space Center. 

I am going to try the X-33 shape of control surfaces added to the existing ones.  My theory is that making the control surfaces larger on the outside increases the speed of the airflow over the center of the lifting body and therefore improve the lift generated.

Missing from this model is the single rudder.  This is only because I have not fitted it back on yet after this model was broken in the move we made after hurricane IKE.  I have scaled the rudder to be the same size as the HL-10.  An observation is that too small a rudder causes the rudder to sit in the lift 'shadow' and is ineffective.  Too large and the lifting body would not turn (weather vane effect) and always face into the wind, which is good for free-flight but not for R/C).  By scaling it to the same shape and relative size as the HL-10 it appears to be the correct during all phases of flight.  I guess the NASA boys know something I don't but there you go.

Standby for more information...

X-24A Radio Controlled

This is the first R/C version created.   The whole body shape was a cone with the motor mounted high up in the cone.  The control surfaces are mounted underneath.   This was not very efficient for thrust or aerodynamics.  It did fly (if you can call lifting body flying) but it had about a 3:1 L/D ratio. 

I retired this model after 2 launches as I was not happy with the overall flight characteristics. 

X-30 Free Flight

This is one of the early free flight models that had no active control surfaces.  The motor ejecting changed the Cg sufficient to make it glide.  The motor only was ejected and came down on a streamer. 

This design is similar to the small Quest HL-20 lifting body kit except changing the shape of the cross section.  The reason for this was that the direction of thrust had to overcome the lifting forces of the body's shape.

The trimming for gliding was too critical and it almost had to be trimmed before each flight. Also changing from coast to gliding mode took a long time before it stabilized it's flight. It was a very small flight envelope that can only be expanded by adding active control surfaces.

X-33 Free Flight

This was the last of the 'Cone' style lifting bodies. I felt that I had reached the limit of what I of what I could learn about this style of body. These models had progressed from pure cone to modified cone shape...to active control surface. They were invaluable to the learning process and were very quick to make. They basically only took a day to make and cost about $5.00 in materials so there was no problem to build multiple ones at a time and try different configurations..

Active control surfaces allow the Cg to be placed further forward which helps the boost as well as the gliding (pitch) stability. It allows the control surfaces to be set the best angle of attack for best glide configuration.  A lifting body classically glides with a CG at about 50% mark.  Having the active control surfaces allows the CG to be at 45% making it fly with more stability.  The elevons allow the angle of attach to be increased producing more lift.