Sperry Messenger (oz1281)
About this Plan
Sperry Messenger. Scale biplane for .010 power, and radio control. June 1969, Model Airplane News.
Quote: "The only alterations are down and right thrust, and a slight increase in dihedral. That's right, all of the surface areas as well as the outlines are exact scale to the best of my abilities; even the incidence angles and wing airfoils are approximately scale.
To obtain all of this performance in a model so close to true scale and as tiny as this one requires just a few unusual approaches to the problems. The main problem is what to do with all of the excess power available in the Cox .010, for it would pull this tiny model straight up if run wide open and unchecked. The answer here is a special restrictor manufactured by Carl Vogt and sold through Ace R/C Inc. This unit wraps around the exhaust ports of the engine and can be instantly adjusted to the proper level before flying. An interesting thing here is the muffling effect of this restrictor; it cuts the engine noise down to an amazingly low purr that cannot be heard 50ft away. The use of a 4-1/2in Cox nylon propeller greatly aids easy hand starting and smoothness of running without harming the engine in any way.
The other factor that contributes to the gentle performance of this model is the use of extremely small, light radio control equipment. The maximum payload that can be carried is about one ounce, with less preferred if possible. The original model uses a radio of German manufacture that has a total airborne weight of less than 3/4 ounce. This is the Bentert receiver and magnetic pulse actuator that is available from Polk's in New York. Although a super-regenerative receiver, the Bentert rejects most interference through the use of a high (3400 cps) tone filter circuit. A special transmitter is required to match the tone and this also is available through Polk's. The Albin receiver from ACE R/C is also suitable and can be used with most American pulse transmitters including the R/O Commander sold by ACE. At this writing the only other actuator that is suitable is the ADAMS Baby AR model which requires a switcher to operate with the currently available receivers.
As for batteries, I have found the S76E hearing aid cell manu-factured by Eveready to be most suitable in this application; with a voltage of 1.5v per cell, all of the afore-mentioned equipment will operate fine on a pair of these. They weigh only 14 ounce for a pair and are widely available wherever hearing aid batteries are sold - large drug stores, etc. These cells are non-rechargeable, however, I get as many as 30-40 3 minute flights on a pair with a Bentert actuator... "
Update 20/12/2017: Added an alternate version of the same plan, thanks to jkexpress. This one shows some further detail. This was posted as a raw scan on Aerofred, I have cleaned and straightened it out, stitched the two parts together. This plan was published in "Radio Control Manual no.4"
Update 21/12/2017: added article, thanks to RFJ.
Supplementary file notes
Did we get something wrong with these details about this plan (especially the datafile)?
That happens sometimes. You can help us fix it.
Add a correction
by Dave Robelen
from Model Airplane News
Scale IC R/C Biplane
all formers complete :)
got article :)
Found online 23/06/2011 at:
Format: • PDFbitmap
Credit*: 50+AirYears, jkexpress
Do you have a photo you'd like to submit for this page? Then email email@example.com
User commentsA careful examination of the lower rudder will show the actuating rod for the single channel, pulse proportional radio that was used. This is, for its time, a very advanced R/C model.
anon - 12/09/2016
Aha, good point. Have tagged this as RC now, Thanks.
SteveWMD - 12/09/2016
Add a comment
* Credit field
The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.
This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.
© Outerzone, 2011-2019.
All content is free to download for personal use.
For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.
Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.