Home › Forums › Free Flight › Electric Free Flight › R/C DT and motor kill
- This topic has 12 replies, 7 voices, and was last updated 13 years, 2 months ago by rivers.
12/27/2009 at 3:37 pm #41283AnonymousInactive
I wanted to start a new thread on this topic. It was starting to be discussed in another topic. Ralph Hotz is doing it here in Phoenix. I feel strongly that this is safety feature that we should all be taking advantage of. Not just for saving planes which it will do but also for the “gallery”. How many time have we seen a model go off pattern or DT into cars.
So I would like to hear comments on using R/C DT AND motor kill in a contest situation. I understand you can’t do it in AMA but should be ok in F1Q. I would like to see it acceptable in AMA as well.
I’m guessing that DT will not be as controversial as the motor kill.
12/27/2009 at 5:40 pm #48349ARAM SCHLOSBERGParticipant
A combination between an e-timer and RDT is almost a requirement for an auto-surface model. It can be used in test flight of any electric model and will keep you out of a lot of trouble.
Presently, I’m using a Roger Morrell F1Q e-timer with an RDT by Ken Bauer http://mysite.verizon.net/resrqa3z/airtek/ . The RDT receiver is plugged in to the e-timer which also powers it (signal, power and ground lines). One programs the Morrell e-timer to go to a specific instruction line upon receiving a RDT signal (technically an interruption). At that instruction line one shuts off the motor, and on the next instruction line, after a short delay (1-2 seconds) DTs the model.
The delay is needed to slow down the model, so not to DT under (full) power. I actually once DTed a model immediately after cutting off the motor using RC reciever on-board and damaged the D-box and spar on a center panel. But if the model is diving, the DT delay might be too long to stop the model hitting mother earth. So a DT delay should be experimented with on test flights. Strong wings are a corollary.
The RDT transmitter should be turned on before initiating a flight. If you have an assistant, he/she would be faster pulling the trigger. Personally, I never fly my auto-surface models without an armed RDT.12/27/2009 at 5:42 pm #48350AnonymousInactive
RDT isn’t an issue in our area and I suspect that it’s time has come in F/F. RDT has terrific potential for small field flying which many people are faced with.
Motor kill could be just as significant and would save a lot of models.12/27/2009 at 7:04 pm #48351Dean McGinnesParticipant
I am completing a T-Bird 650 which incorporates RDT and Engine kill for testing. There is a conventional Texas Timer MAX-IIIA for contest work, the RDT being removed for that purpose.
I have considered keeping the radio system in the airplane for constest flying depending on finished model weight. The advantage would be a backup to the timer for engine runs or if it goes off pattern due to me making a bad launch re: wind direction.
I have nearly completed the rough installation & will post pictures soon.12/27/2009 at 9:39 pm #48352
Here is the excerpt from the 2009 FAI rules for F1Q electric:
F1Q models may use radio control only for irreversible actions to restrict the flight, that is motor stop and/or dethermalisation. Any malfunction or unintended operation of these functions is entirely at the risk of the competitor.
I use the Ken Bauer RDT same as Aram, but with my own timer. I had Ken reprogram the RDT receiver to have power on all the time. Otherwise, there is a periodic battery-saving 1 to 2 second delay. For motor stop in an emergency situation we don’t want any delay.
Dick12/28/2009 at 2:09 am #48353
The AMA 2009-2010 rulebook covers radio DT in the General Section 2 :
2. General. A Free Flight model airplane is flown without controlling or guideline(s) and without any control of functions by radio except that the dethermalizer function may be radio operated from the ground by the contestant. All Radio Frequency Operated DeThermalizer (RFODT) units shall be commercially available. Frequencies shall be used that pose ….
There is more, but too long to include here. Check it out on the AMA website.
Motor kill is not covered, but I agree it should be.
Dick12/28/2009 at 4:12 am #48354ARAM SCHLOSBERGParticipant
F1Q termination of motor runs was introduced in the FAI sporting code as a mean to speed up the development of these models, allowing RC to replace a simple e-timer on board. Note that the transition (bunt to glide) is not included.
One can argue that a similar provision should be included in the AMA rules to be in sync with FAI rules. But the window to introduce such a rule change is closing quickly at the end of December. Will anyone volunteer to introduce the rule change this week?12/28/2009 at 2:42 pm #48355George ReinhartParticipant
AMA rules are not FAI12/28/2009 at 3:27 pm #48356Roger MorrellParticipant
Clear omitting the ability for a Radio D/T to cut the motor is just an over sight. With either an electric or gas powered model operation of the D/T under power could be more dangerous that not operating it at all.
In reference to Dick’s comment about the Airtek RDT, Ken Bauer is fanactical about conserving power so the response in not instantaneous but even with a standard unit is quite quick. There are other Radio D/T units on the market that work with my Black Magic timers too. Ken’s is probably the smallest and lightest. With an electric model the power conservation is not a issue as the power consumption by the control system is trival compared with the motor.
I do have one timer – the 4 servo model – or for you electric guys 3 servo plus motor controller where you can either use a purpose built RDT like the Airtek or a regular R/C RX. The latter just uses one channel that you move from one limit tot he other to D/T the model. It does not do regular R/C like functions.
In the Magic timers you can select what you want to happen on receiving the RDT command, in particular any delay that might be appropriate – do you could cut the motor and wait a short period before activating the D/T or you could make them work both at the same time. This is something that you set up during the trimming process.
Roger Morrell12/28/2009 at 4:48 pm #48357
I checked the Contest Board Procedures on the AMA website. We have until March 15, 2010 to submit Basic rule change proposals. That is the cutoff date.
We all seem to agree that a motor kill update to the AMA RDT rule is needed for safety reasons. So, will someone volunteer to write and submit an updated rule for consideration by the Contest Board?
Edit: No one volunteered so I will do it. Look for the rule change proposal on the AMA website in about one week.12/29/2009 at 8:36 pm #48358AnonymousInactive
I just pulled up the form to submit. I was working on the wording and then thought of another thing maybe we should clarify.
Should we put wording in it that specifically rules out the use of R/C for purposes other than motor kill and DT?
I really appreciate everones input on this subject. Again thanks to Dick for taking the bull by the horns.12/30/2009 at 7:19 pm #48359Roger MorrellParticipant
I suggest that you use the word radio rather than R/C when defining the rules. The units used are not necessarily conventional R/C units.
You could say that radio is only permitted to activate the engine cut off or stop the motor and activate a D/T to terminate the flight. In all cases the action must be non-reversable.
Roger12/30/2009 at 10:15 pm #48360
The above suggestions are noted:
I’ve added the word “irreversible” per Roger’s comment.
The term R/C will not be in my proposal, nor is it used in the existing AMA rule regarding radio frequency operated DT. Also, the current AMA rule specifically excludes any control of function other than DT. Of course my new proposal will add motor stop as an allowed radio function.
I’m sending my proposal to Greg Hahn tomorrow. I can edit and change my proposal any time up to March 15. Anyone else can submit their own proposal up to that date. After March 15 anyone can submit a cross proposal to alter an existing proposal.
Edit: Done …. see AMA website
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