Author: Bob Aberle
Edition: Model Aviation - 2010/04
Page Numbers: 84,85,86
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Frequently Asked Questions - 2010/04

Q440 — A 14-gram, six-channel-function P-51 Mustang

Q440: "I had heard on several of the RC forums that a 14 gram scale model of a P-51 Mustang won the Best Micro Aircraft Award at the Keystone Indoor Electric Fly (KIEF), held in Muncy, PA this past October. Can you tell me the details of this model, who designed it and possibly show a few photos?"

A440: Martin Newell of California, a noted micro flier, designed and built the winning P-51. It has a scale of 1/48 and weighed a total of only 14 grams (1/2 ounce). The model has a wingspan of just 9.25 inches and a wing area of 14.8 square inches.

Martin custom-made the radio system, which uses six channel functions. Despite the micro size and weight, this aircraft has aileron, rudder, elevator, motor throttle, flaps, and retracts.

The power system is a Hextronix 2-gram brushless motor swinging a 2.5 x 1.0 propeller running on a single 70 mAh Li-Poly battery cell.

One of the pioneers of micro RC flying, Matt Keennon, is a project manager at AeroVironment. He did the Mustang’s demonstration flying to the delight of KIEF spectators.

Martin’s web page describes the details of this micromodel and has a YouTube video link that shows how all the controls work. This little gem even has flashing wingtip lights.

You can find a detailed report of the 2009 KIEF event in the November 2009 issue of John Worth’s RC Micro World online magazine (see Sources).

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Q441 — Rough-field takeoffs and Cessna-type landing gear shock absorption

Q441: “I fly from a very rough field. Hand launching my smaller models is no problem. But when I have to take off and land on my field, usually my plane ends up on its back. I suffer structural damage occasionally, and many broken props.

“I’ve tried various brands of wheels (tires) and that doesn’t seem to help. Most of my landing gears are the sheet metal type that is often referred to as a ‘Cessna Landing Gear.’ Is there such an item as a shock absorber for this type gear?”

A441: Yes—there is a simple modification that provides shock absorption for the common sheet-metal Cessna-style landing gear. My fellow SEFLI (Silent Electric Flyers of Long Island) club member Casey Brandsema showed up at our field with a reworked metal gear that includes a shock-absorbing feature.

Basic concept (you will need to adapt dimensions to your gear and model):

  • Cut the metal gear roughly at the halfway point.
  • On the lower part (the axle/wheel section) cut two elongated slots, sized to accept either 6-32 or 8-32 screws (use the larger screws for heavier aircraft).
  • Assemble the two gear pieces with the two screws so the lower half can move up and down in the slots.
  • Install an O-ring or rubber band to hold the lower gear at its full extension. When weight is placed on the wheel during landing, the lower half travels up slightly, absorbing shock.

I made a mock-up and have photos of Casey’s aircraft and the fabrication steps. If you’d like, e-mail me and I will attach roughly six pictures in a reply.

One caveat: this modification shortens the overall gear length somewhat. If your current gear is not long enough, you may need to purchase a longer gear and substitute it.

Let me know how you make out.

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Q442 — Repetitive beep from Castle Creations ESC

Q442: “I own a Castle Creations ESC that controls my brushless electric motor. After hooking everything up and making sure the motor ran throughout its full speed range, I heard a single audible beep. While contemplating what my problem might be, I heard another beep.

“Still pondering a potential problem I heard yet another beep. I discovered that this beep occurs about every 30 seconds. Like I said everything works as it should, but can you tell me what the ‘beep’ is for?”

A442: I noted this repetitive beep on two Castle Creations ESCs (a Thunderbird-6 and a Phoenix-10). The manual did not explain it, so I contacted Castle Creations. They said the beep is programmed into most (if not all) of their ESCs as a periodic self-check to indicate the unit is operating normally.

When you hear the beep at regular intervals, all is well. The alarm is also handy if you forget to power down your model after a flight. If you do not hear the beep, check for installation or programming issues. In short: the beep is a good thing.

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Q443 — TME Xtrema xG Balancing Charger and Wattmeter bundle

Q443: “I recently saw an advertisement for Tejera Microsystems Engineering, Inc. (TME) for what appears to be a bundle deal that includes both their Xtrema xG Balancing Charger and Wattmeter. Can you shed any light on this offer?”

A443: Albert Tejera of TME has combined two of his products into a package deal at a considerable savings. Both items are excellent quality and well documented. MA’s resident battery expert, Red Scholefield, has recently reviewed both products, so I won’t repeat that review here.

I’ve listed TME’s contact information in the Sources section. Their website allows you to download the instruction manuals so you can learn the full feature set of each product.

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Q444 — Difficulty identifying old-timer and nostalgia rubber and gas model plans

Q444: "I'm interested in old-timer and nostalgia rubber and gas models plans. But I have to admit that most plan listings by name alone make it difficult to identify the particular models. As a result I have bought plans, only to find out it wasn't what I wanted. Do you have the same problem?"

A444: Yes. Some plan services include a photograph or sketch in their listings, which is very helpful. One plans service that stands out is Jim O'Reilly Model Plans of Wichita, Kansas. Jim is the current president of the Society of Antique Modelers (SAM) and his service uses CADAM.

On Jim's website you can see plan categories such as "Old Timer Rubber-Powered," "Old Timer Gas," "Nostalgia Gas," "Nostalgia Rubber," "AMA & Misc.," and "Scale Models." Clicking a model name opens a small rendition of the plans—great for identification. Because the plans are CADAM-based, Jim can print sets to any size quickly, and he is associated with Bob Holman for laser-cut parts.

See Sources for contact information.

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Q423 Follow-Up — Jet fuel, bacteria, and fuel residues

In response to the Q&A published in November 2009, AMA member Tony Vlasak provided these comments (published with permission):

  • The main restriction on commercial jet fuel purchase is that it is not to be bought for motor vehicle fuel because appropriate taxes are not applied.
  • Jet fuel lacks the lubricating qualities of diesel and will not develop as much power as diesel fuel for motor-vehicle use.
  • Jet fuel should not be stored for long periods because bacteria can grow at the water/kerosene boundary. This bacterium is extremely corrosive. Jet operators use a product called Biobore (a derivative of borax) as a fuel additive to prevent this growth. Aircraft with wet wings must use an additive; bladder tanks reduce the threat but do not eliminate fuel-flow limitation if the aircraft is inactive.
  • Residue found in filters can be very small fibers from filters in the fuel path from refinery to container, possibly originating at the last pump at the airport.

Thanks to Tony for the clarification.

Sources

11705 Boyette Rd. #418 Riverview, FL 33569 www.tmenet.com

  • Jim O'Reilly Model Plans

Phone: (316) 744-0856 www.jimoreillymodelplans.com

Transcribed from original scans by AI. Minor OCR errors may remain.