My best time in Cat 1 For F1L is a little over 14 minutes and was with a
1.46g motor. My best time flying an F1L as an F1D is 11:23 on a .6g
motor which I thought was surprisingly good but wouldn't lead me to
lighter motors. I think Leo flies 1.0g in F1L and it obviously works
well for him.
On 10/27/2013 11:41 AM, Nick Ray wrote:
> Hi Gary,
>
> I think the current 55cm F1Ds are a contradiction to 1.4 times the
> model weight being the best way to go about optimizing the rubber
> weight. When the rules were written it was thought that the 50% rubber
> weight rule would drastically reduce duration but in actuality its has
> only reduced the duration by about 20%.
>
> Lew Getlow published a table in his book of optimal rubber to model
> ratios. I do not have my copy with me so I cannot provide a page
> number. I think information provided there may be a decent starting
> point. Personally I have found that I do best when I fly motors that
> are about 100% of the models weight.
>
> Regards,
>
> Nick
>
>
> On Sat, Oct 26, 2013 at 7:50 PM, <Warthodson_at_aol.com
> <mailto:Warthodson_at_aol.com>> wrote:
>
> Thanks Nick,
> Just for the record, I was not looking at the absolute value of
> the predicted flight time when modeling A6's using the Hunt
> program, just the relationship of the results & the % difference
> between them. For example, I might model my current A6 & an
> identical one with a tail boom that was 2" longer & see what the
> affect was on predicted time. In this example I might assume that
> I could simply make the tail boom longer but not increase the
> weight of the boom or I might decide to increase the weight of the
> boom proportionally to the length & assume I could save that
> amount of weight somewhere (like the motorstick). If the predicted
> time increased by 2 seconds I would probably have decided that it
> was a dead end, but if the time increased by a significant amount
> (what ever that is) I might try building & testing one.
> I am interested in the premise that the rubber weight should be
> 1.4 times the model weight for all classes. Nick, have you or
> anyone else examined this premise to see how well it holds up in
> the real world? In classes where the front bearing to rear hook
> dimension are limited, like A6, the 1.4 might not be applicable,
> but in classes with more dimensional flexibility I would be
> interested in knowing if the 1.4 is proving to be a reasonably
> accurate guide line.
> Gary H
> From: Nicholas Ray <lasray_at_gmail.com <mailto:lasray_at_gmail.com>>
> To: Indoor_Construction Indoor_Construction_at_yahoogroups.com
> <mailto:Indoor_Construction_at_yahoogroups.com>
> Hi Gary,
>
> You are correct that the Hunt program is mainly concerned with the
> models sink rate as a glider. Hunt figured out a factor, 14.63
> divided by the sink rate times prop diameter efficiency factor.
> This equation accurately predicts duration of old rules F1Ds with
> a 1.4 gram motor.
>
> The duration prediction corrected for the low rubber ratio is the
> rubber weight divided by the 1.4 times the model weight. Based on
> this equation, I believe that Hunt thought the rubber weight
> should be 1.4 times the model weight for all classes. However, as
> the rubber weigh decreases, the sink rate improves. So, there may
> be a good compromise between sink rate and rubber weight some
> where in between.
>
> For A-6, the prop efficiency factor is considerably outside the
> expected inputs of the program. The program compares everything to
> an 18 inch F1D prop. A prop less than 18 inches is considere d
> less efficient with a factor less than one, while a prop greater
> than 18 inches has an efficiency factor greater than one. Because
> A6 uses small flat bladed props I would be wary of any duration
> predictions the program makes.
>
> Regards,
>
> Nick
>
> Sent from my iPad
>
>
>
>
Received on Sun Oct 27 2013 - 09:04:31 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:48 CET