FrSKY Horus X10s help please.

[John Timmis]

Hi all, I have just acquired this new radio & am setting up the first model. I’m at the bottom of the learning curve.  
All the controls are good & the gyro is working so it should be good to fly.  The problem is that I think I have far more power than is needed.  The model is Boddo’s Chiltern DW1 , the motor is a Quantum 40 on 6s.  The watt meter showed about 1.4 kw.

The question is, ‘ Do I fly it as it is, or can the transmitter be set up to limit the power?’  Can an end point be set on the throttle as in the flight controls?

Some say that you can’t have too much power, I’m not so sure.

All advice/opinions welcome.

Cheers Johnl

[Andy Gates]

John,

 

Leave the radio alone in regards to setup.

 

When you come to fly, SLOWLY increase the throttle and keep it straight.

 

You do not need to use full throttle.

 

Once you know it flies OK, play with prop sizes and try other packs to see what works for you best.

 

Best of luck.

[Philip Lewis 3]

20 minutes ago, John Timmis said:

Can an end point be set on the throttle as in the flight controls?

The short answer to your question above is yes, whether you are using FrSky Ethos, Open TX of Frsky's old OS. All can have the throttle end point lowered if you so wish. Only alter the high point from +100 backwards don't touch the low end point or it might not arm.

[Frank Skilbeck]

Be careful in doing this as the ESC may learn the new max throttle position, much better would be to reprop it for less power, or change to a 5s or even 4s battery.

 

BTW what size is the DW1, the only Boddo one I can find is 48* wingspan for a 26 fourstroke, a "tad" less than 1.4 kw!

Edited September 14, 2022 by Frank Skilbeck

[John Timmis]

Thanks for your advice chaps. The Horus is a bit more demanding than my old Futaba.

Frank, you found the correct model, there was a option to build a larger version 64” span.

I think it would fly on 4s but then I would have to ballast the model to get the cg right.

I”ll have to get myself “ psyched up” to give it a go.

Cheers John

[Frank Skilbeck]

John, so you've got the 64" version, which was designed for a 40, say 0.9 HP around 700 watts, I think it will be pretty ballistic on 1.4kw and a 6s, surely a 4s setup with more mah if balance is a problem. 

 

 

[Ron Gray]

If you want the TX to limit the throttle then set up a throttle curve, that way the end points can be left at +100 -100.

[MattyB]

15 hours ago, Andy Gates said:

John,

 

Leave the radio alone in regards to setup.

 

When you come to fly, SLOWLY increase the throttle and keep it straight.

 

You do not need to use full throttle.

 

Once you know it flies OK, play with prop sizes and try other packs to see what works for you best.

 

Best of luck.

15 hours ago, Philip Lewis 3 said:

The short answer to your question above is yes, whether you are using FrSky Ethos, Open TX of Frsky's old OS. All can have the throttle end point lowered if you so wish. Only alter the high point from +100 backwards don't touch the low end point or it might not arm.

12 hours ago, Ron Gray said:

If you want the TX to limit the throttle then set up a throttle curve, that way the end points can be left at +100 -100.

 

I'm afraid I am going to vociferously disagree with these posts! At present based on the meter readings and Frank's calculations you have roughly twice as much power as needed. I don't know the model in question, but if you fly with the current setup that level of power could well be beyond what the structure can withstand. If anything unexpected happens whilst trimming out (when pilot loads are highest), you'll also need to remember at a moment of high stress not to open the throttle fully! No thanks. This needs to be addressed on the ground before flying through powertrain optimisation, not with a sticking plaster TX fix (i.e. limiting the throttle throw or applying a curve) that will stress the ESC and could cause it to fail in the long run.

 

Let's assume you are targeting ~700-800W at full throttle. This can be done by changing some mix of prop, cell count or (if no other options exist) motor. Personally I would start by bench running your current setup on a 4S pack of similar capacity, and seeing what you get - if it's in the sweet spot you can fly with that. If it's too little your cheapest option will probably be to prop down on 6S, but you could also look at running on 5S or fitting a lower KV motor on 6S. This is why it's important to model the powertrain on something like eCalc before you buy components, as this can avoid making expensive wrong choices. Whatever you do though, don't try a flight until this is at least in the right ballpark and you are confident no elements of your powertrain are operating outside their rated limits, as it would be a shame to lose such a nice model to incorrect powertrain choices.

 

EDIT - I just looked up the motor in question; at 210g with a maximum constant current rating of 60A you must be operating it miles outside it's max power in your current setup (that is an 800W motor at maximum). Your ESC must also be being pushed very hard if it is a 60A one. Please don't fly this setup without some tweaks or magic smoke is highly likely to appear! 

 

Edited September 15, 2022 by MattyB

[Ron Gray]

The OPs question was can the Tx be setup to limit the power and answers (including mine) were given so no good you vociferously disagreeing with those answers as they were correct!

 

Your points and those of others regarding the power are obviously valid.

[MattyB]

10 minutes ago, Ron Gray said:

The OPs question was can the Tx be setup to limit the power and answers (including mine) were given so no good you vociferously disagreeing with those answers as they were correct!

 

Your points and those of others regarding the power are obviously valid.

 

Fair point - I just thought it was important to point out that, whilst what the OP is asking is possible in the TX, that doesn't make doing it in this instance a good idea. Taking off with a powertrain that overloaded is asking for trouble, especially with a model that is brand new and not rimmed out...

[Philip Lewis 3]

23 minutes ago, Ron Gray said:

The OPs question was can the Tx be setup to limit the power and answers (including mine) were given so no good you vociferously disagreeing with those answers as they were correct!

 

Your points and those of others regarding the power are obviously valid.

Exactly what I thought Ron, I think it's only fair to answer the question asked as the OP is new to the TX and answering the question increases knowledge which quite likely can then be applied to alternative and other situations.

 

Too many questions asked that are answered with "you don't want to do it that way", nothing wrong with suggesting alternatives but at least answer the question that's been asked.. 

[John Timmis]

Hi all, thanks to everyone who responded. All the opinions were helpful & I have learned something from them all.

I have taken the advice from Matty. A 4s Lipo gave me 680 watts on a 13 x 6.5 prop , that is much more comfortable.

Swapping to a smaller lipo also enables me mount the lipo vertically & further forward so hopefullyI may not need to add lead to correct the cg.

Happiness all round. 
Thanks again, cheers John

[MattyB]

On 15/09/2022 at 15:12, Philip Lewis 3 said:

Exactly what I thought Ron, I think it's only fair to answer the question asked as the OP is new to the TX and answering the question increases knowledge which quite likely can then be applied to alternative and other situations.

 

Too many questions asked that are answered with "you don't want to do it that way", nothing wrong with suggesting alternatives but at least answer the question that's been asked.. 

 

Clearly by saying that I "vociferously disagree" I have put peoples backs up, but that was not my intent. I wasn't disagreeing with how posters had suggested to limit the throttle in the TX (that had clearly been answered correctly by others, hence why I didn't offer a the same text again); I was disagreeing that doing so is ever a good idea.

 

What none of those posters had pointed out was that both the motor and ESC were almost certainly operating well outside their design parameters, an issue that could result in one or both burning out causing the loss of the model. Limiting the max throttle in the TX might seem to "solve" that issue, but doing so means the ESC will be working hard for a far higher percentage of the flight, and may fail prematurely as a result. This is why testing using an online calculator before buying powertrain components is key, and doing a static check to validate that data (and then acting to adjust the powertrain if something unexpected is found) is absolutely key.