National Free Flight Society

SEN 2438

  1. Romanian Results
  2. Spence site change
  3. LiPo for John’s F1A

Romanian Results
From:Bogdan Lemut

Salonta Cup results (photos) on Borut’s aeromodelling forum:

Szabo Miklos Memorial – official org.results:



Editor’s Comment – Thanks Bogdan

Spence Memorial  site change
From: Steve Spence

Due to the unfortunate loss of our Denton, TX flying site the Spence memorial will be held on June 2 & 3 at our Gainesville, TX site.

The LiPo for John’s F1A
In reply to the suggestion, in the last SEN  that he replace his 5 cell NiMH with a single cell LiPO John asks…

When you say single cell, ya mean the 3.7 V deal?
Tnx John

To which Mr Magic replied

Yes. But 3.7 is a nominal voltage. They have 4.2 when fully charged. And typically in my F1B after a days flying will still be at 3.8 or 3.9 volts. Many people with traditional F1A gliders, including bunters use a single LiPo un-boosted to drive the timer and servo[s]

All F1Bs use a single cell and most use a standard servo – a Dymond D47 that is a 5-8 volt servo. I have 3 servo F1Bs that move the wings running o a single LiPo.

For an F1A I would look at 250 ma provided you have the space. One reason why it works is voltage drop is lower and LIPo can deliver more current than a Regular NiMH so even though the nominal voltage may be lower more is getting to the servos under load.  This works for a “traditional” F1A for a high speed LDA or Flapper you would need something more robust. A few years back before the LDA era a well known F1A sportsman made up special NiMH battery pack to fit the pod of his F1As. Unfortunately the NiMH batteries chosen were consumer level (because they were the right size to fit) and so not as good as the ones supplied by top quality hobby sources.  What happened was the voltage dropped off during the launch and occasionally would cause the RDT to reset and DT the model or other similarly embarrassing behavior from the servos.  The solution to his problem was to replace the NiMH pack with a single LiPo ( a “new thing” at that time) which performed flawlessly.  On standard Magic Timers  that most used in that era and probably on your F1A too, there is no voltage regulator on the power to the servo so it gets the full benefit of the battery voltage. The voltage to the microcontroller is regulated.  The timer itself will continue running at a voltage under 3 volts, but probably not the servos.

The final word is that any time you try something like be sure to “test fly it for a full flight” on the ground checking the voltage before and after the “flight”