"Builder of the Model" rule vs. composite construction
Bob Hunt [[email protected]]
I didn't have much in mind to write about this month, so I decided to "blue sky" a bit about things that have been on my mind concerning modern CL Stunt model construction, how it is affected by the current event rules, and how it may be affected in the future by potential rules that many have proposed recently.
The entire CL community is traditional and not normally prone to sweeping change or rapid adoption of new technologies. There are exceptions, but by and large the community is slow to change. Many are quick to defend long-standing rules and concepts. That's not necessarily bad; changes shouldn't be made just for the sake of change. Sometimes change is good, and sometimes it is unavoidable.
There has been decades-long discussion about the "Builder of the Model" (BOM) rule in CL Aerobatics—some like it and some don't. Supporters cite that this is how the founders intended the event, and that eliminating the BOM would diminish the artistic and craftsmanship aspects of the event, lower model quality, and erode mystique and exclusivity. They view building, finishing, and flying as all part of the event. Those are valid points.
Opponents note that FAI F2B rules have not included a BOM requirement for many years, yet model quality at FAI events has not diminished. Removing BOM has allowed increased participation for those who cannot build their own models (time, space, health, etc.). They point to many sports where competitors need not build their own equipment (Dorothy Hamill didn't make her own skates; Jeff Gordon didn't build his race car). Some feel BOM stifles participation in what they consider mainly a sporting event and discourages development of new construction techniques. Those viewpoints have validity as well.
We need mature, logical discussion on all points of view to find common ground. The BOM debate has simmered for a long time but recently boiled over with the introduction of ready-to-fly, high-end commercial CL Aerobatic models from several sources worldwide.
The models that brought this into focus are the Shark and Classic designs made and sold by the Yatsenko brothers—Yuriy and Andrey—from Ukraine. They run Discovery Aeromodels. The brothers are engineers who work for the Antonov aeronautical design complex, and they apply aerospace thinking to their models. Their designs fly very well and have scored highly at world events. In the hands of Orestes Hernandez, they have won the US Nationals on two occasions.
On both occasions Orestes provided documentation to the Nationals Event Director verifying that he constructed the model he used from parts supplied by the Yatsenkos to comply with the BOM rule. In other words, they supplied him with an actual "kit" for the Shark. Currently the Yatsenkos offer their models in three phases of construction to allow compliance with current AMA BOM rules. One phase is an all-balsa kit that must be assembled, aligned, and completely finished by the modeler.
Much of the Yatsenko brothers' construction is done in hyper-accurate molds and incorporates aerospace-type materials and concepts. Composite construction is here to stay. Unfortunately, most composite parts come out of molds with a smooth finished surface (paint or gelcoat) that may render them illegal for CL Stunt under some interpretations of the BOM rule when purchased by a flier.
The current thinking in many quarters is to interpret BOM to disallow any component purchased with the surface finish already applied. Since many composite parts leave the mold with a finished surface, there is disagreement about how that rule should be applied.
There is no argument that if a builder makes his or her own molds and produces molded composite parts for personal use, the BOM has not been violated. The concern is that if those parts are sold to others, resulting models may be illegal for competition because the purchaser did not apply the surface finish.
Not everyone can—or wants to—produce homemade composite parts. The high cost of molds and the time to learn techniques can be significant. There is a steep learning curve, but it can be mastered with sufficient time and money invested.
My friend Jose Modesto has invested time and money to develop his own line of composite models and components with the intent of producing composite models for sale—much like the Yatsenkos. Several local modelers obtained parts from Jose and crafted good-looking, good-flying airplanes. With the announcement of the BOM interpretation for this year's Nationals, those fliers worried their models might be declared illegal. The same concern applied to those intending to fly Yatsenko models.
Jose found a creative and unselfish solution: he invited interested modelers to his home to lay up their own composite parts in his molds. That assured them their parts were BOM-compliant because they produced the finished parts themselves. One flier who took advantage of Jose's offer was Will DeMauro, an up-and-coming Advanced-class flier on the East Coast. Will made several trips to Jose's house and, under Jose's guidance, built a new SV-22 Nationals model in a few weeks. The result was the best-flying aircraft Will has owned, and he placed higher at the Nationals than ever before. He credits the accuracy of the composite components and Jose's alignment procedures for his improvement.
Perhaps Jose has shown a way to integrate composite construction acceptably for many competitors. However, not everyone can travel to Jose's house. Those who want to try this construction in a region could pool resources to develop tooling (molds) and share them, provided they agree on a specific design.
In checking with Jose, he told me that, like the Yatsenkos, he is now producing kit versions of his models that are totally BOM-compliant and will soon have information available for interested modelers.
This still does not address the legality of many premolded components sold worldwide. At this time, such parts are legal for FAI competition, but their use at our Nationals depends on the BOM interpretation in effect.
I should declare my position: I have long contended that we should adopt the same rules used by the rest of the world if we intend to be fully competitive at FAI events. To fly under those rules just once each year—at Team Trials and once at Worlds—seems silly, especially when other world competitors use those rules all the time. Not many agree with me on that point.
There are people who want BOM eliminated entirely in this country, and others who want it made more restrictive. I'm fairly confident we will retain some form of BOM rule, but it will take give-and-take to find one acceptable to all. Let's try to make that happen. Please send in your thoughts and we will print some comments here. A more in-depth discussion could take place in the pages of Stunt News, the official newsletter of the Precision Aerobatics Model Pilot's Association (PAMPA).
To be fair in this discussion I should mention that the BOM rule applies in our rules in two instances:
- At our Nationals, for the CL Precision Aerobatics (CLPA) age-category competition (Junior, Senior, and Open), the BOM rule applies to be eligible to compete. The age-category competition is normally only found at our Nationals.
- At all other CLPA contests in this country, the AMA skill classes are used where the BOM rule is not required to compete. However, if the competitor did not build the model, he or she can still fly in the skill-class competition but will not receive appearance points. Event organizers can also announce beforehand that BOM is not required and that appearance points will not be awarded; this approach is used at a number of contests around the country.
My thanks to Keith Trost for his help in clarifying the actual implementation of the BOM rule in competition. Keith and I agree on some points and not at all on others, but we are able and willing to work together to find common ground. Hopefully future BOM discussions can be conducted similarly.
Spray adhesives ... again
I've written recently about 3M spray adhesives and their applications for model building. Some readers have shared personal experiences with these and other adhesives. I received a contribution from C.J. Sasso about an adhesive he found useful. C.J. wrote:
"Hi Bob: I am writing in reference to your recent column on 3M adhesives in Model Aviation magazine. I was a user of 3M #77 adhesive to adhere balsa to my white foam sailplane wing cores several years ago. Recently, when I needed spray adhesive again, I learned there had been a change in the #77 formulation. About a year ago, while comparing products on the shelf, I found a Loctite product titled 'High Performance Spray Adhesive.' The label said it was safe for foam. I didn't trust labels completely, so I tested it on scrap foam.
"Typically I use 3/4-ounce cloth in the building process. Besides attaching balsa to foam cores, I epoxy glass directly onto foam tail surfaces and use spray adhesive lightly to hold the glass in place.
"From testing and experience, the Loctite product works very well and is perfectly safe on expanded polystyrene foam. I think it works better than the old 3M #77 formulation. The Loctite tack is not as aggressive as #77, making it easier to position pieces and to lift and reposition sheeting before full setting.
"I found the Loctite spray adhesive at Lowe's and Walmart in my area. After reading your column I thought it might be worthwhile to share this info with you and your readers."
Thanks, C.J. It's great to have another tool in our building arsenal.
Till next time, fly Stunt!
Bob Hunt
Sources:
- Discovery Aeromodels — http://discovery-aeromodels.com
- PAMPA — http://www.control-line.org
Transcribed from original scans by AI. Minor OCR errors may remain.
