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DLE20 conundrum

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Winco Steve28/09/2017 13:06:19
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198 forum posts
1 photos

Good afternoon all,

I wonder if anyone can throw a sparkle of light on this issue. I have a DLE20 in my Nieuport. I am using a Fatuba T6J transmitter. All the normal adjustments have been made in relation to servo end stops, trims, centering etc. All appears to be satisfactory. Here is the issue. The servo, on demand, will open (fully) the carburettor and also fully close the same. Midway of throttle stick operation gives 50% opening travel of carburettor (as indicated by the metal disc that locates against both end stops). Same goes for 25% and 75%. However, when the engine runs full power is reached just around mid point of stick travel with no appreciable increase of RPM as stick is pushed to fully open. I'm thinking something to do with throttle curve? When checked, on the T6J, all points are correct as being 0%, 25%, 75% and 100% as throttle is opened. Carburettor issue? Opens 100% and close 100%. Mixture? As best can say is correct with small adjustments being made but no correction obtained. Fuel /oil mix, correct.

Spark plug correct and reasonable burn colour. There is no exponential setting for throttle so this can not be the cause.

So, any ideas? I have probably missed out some important fact here so if any gaps please ask.

I will continue to investigate and will be borrowing another DLE20 to see if action is the same.

Regards to all, Winco Steve (AKA confused)

Edited By Winco Steve on 28/09/2017 13:07:04

Jon - Laser Engines28/09/2017 13:55:11
4789 forum posts
179 photos

Pretty standard stuff on petrol engines with butterfly carbs from my own experience. Tweak your throttle curve to make it more linear. I did this on a friends DLE 20 as it was not nice to use in the first instance. We also leaned off the slow run massively and added a 2 second delay to the throttle channel to give a smoother midrange but keep the engine from cutting on throttle up. The changes made it better but it wasnt 100% sorted. He crashed the model before we got any further. 

Edited By Jon Harper - Laser Engines on 28/09/2017 13:57:10

Winco Steve28/09/2017 14:13:47
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198 forum posts
1 photos

Hi Jon,

Thanks for reply. I think I might need additional guidance on the throttle curve as 1. Have never used it and 2. Instructions are not very clear. Crashing seems a rather rash method of solving the issue!😂

Regards, Winco Steve

Jon - Laser Engines28/09/2017 16:22:05
4789 forum posts
179 photos

Yes, he ran out of fuel having been reminded several times it was low. The dead stick was then mishandled and resulted in a spin from about 20 feet. It was a shame, but was a lesson in trying to fly a model beyond one's ability.

Petrol Pete28/09/2017 20:00:50
15 forum posts

Hi Steve,

I always use a throttle curve on my petrol engines, the have a very big carb for the engine size, I normally start with a setting of about 25% open for 50% stick movement, and then just adjust the curve until general flying is about 1/2 throttle on the transmitter

Winco Steve28/09/2017 20:17:35
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198 forum posts
1 photos

Hi Pete,

Thanks for that bit of information which may well point me in the right direction. So, if I understand correctly, I set up the curve as 0% closed, 25% at 50% stick movement then adjust to obtain max rpm / full open at full stick movement?

Cheers, Winco Steve

Denis Watkins28/09/2017 21:07:44
3874 forum posts
58 photos

Drop your prop diameter an inch, just to unload the motor a tad, and try that 1st.

Winco Steve28/09/2017 21:43:41
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198 forum posts
1 photos

Hi Denis,

Thanks for input. Have tried this ( from 18 to 17 ins) and had no effect. Trying the throttle curve tomorrow and see how we go. Having read more and now understand the section in the manual about throttle curve I think this could be the right path to follow. Will post results.

Cheers, Winco Steve

john stones 128/09/2017 21:48:52
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10577 forum posts
1480 photos

17 x what Steve ? sounds a lot of prop for a 20.

Winco Steve28/09/2017 21:58:37
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198 forum posts
1 photos

Hi John,

It's a 17x6 which, according to the DLE20 manual, is an appropriate sized propeller. A friend has run the same combination on his model with no problems. After discussing further with him he seemed to recall a club friend did set up his throttle curve but could not remember exact details.

Winco Steve

john stones 128/09/2017 22:08:20
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10577 forum posts
1480 photos

Yep 17x6 is recommended, throttle curves are easy enough Steve, you can tweak it to get the desired effect, numbers are just a starting point.

Winco Steve28/09/2017 22:11:14
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198 forum posts
1 photos

Hi John,

Yes, bit of experimentation tomorrow in the shed and on the field. It's what makes the hobby such a joy!

Cheers, Winco Steve

john stones 128/09/2017 22:16:55
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10577 forum posts
1480 photos

Which Nieuport you got..picture ?

Winco Steve29/09/2017 07:42:45
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198 forum posts
1 photos

Hi John,

It's the Maxford 1/5 scale. A well constructed aircraft with some nice detail. Running the engine tests today with particular attention to throttle curve. Will fix wings on post photos along with test results.

Regards, Winco Steve

Rich too29/09/2017 07:49:26
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3002 forum posts
1061 photos

Steve, I assume that you are using a small servo arm no longer than the lever on the carb? I had similar issues with a dle30 and changed the servo arm which sorted it.

Winco Steve29/09/2017 11:10:48
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198 forum posts
1 photos

Hi Rich too,

The servo arm is the standard length I always use for throttle control. It is longer than the one on the carburettor end but I would of thought this an advantage rather than a disadvantage? Probably wrong ,need to do the maths! I will certainly try your recommendation as it would, if a solution, provide an easy and quick fix. Thank you for your help. I will post results.

Cheers, Winco Steve

Rich too29/09/2017 12:42:06
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3002 forum posts
1061 photos

I think you will see much better results going the same size, or even slightly smaller - definitely not bigger! You will be surprised how small you can go and still have the full range of movement. Good luck.

Edited By Rich too on 29/09/2017 12:42:38

Jon - Laser Engines29/09/2017 13:29:18
4789 forum posts
179 photos

Rich is right, a longer arm on the carb will be better for you. It will also allow a leaner slow run mix as the rate at which the throttle opens will be slightly reduced. This should give a better mid range run as well.

Although its for slightly different reasons, i am likely to use a slightly longer than normal arm on our petrol carb once its finished.

Winco Steve30/09/2017 09:44:46
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198 forum posts
1 photos

Hi all,

Interesting about longer carburettor arm. Is there an easy method to achieve this bearing in mind the petrol carburettor has a fixed metal cam shaped arm? Still experimenting with throttle curve and having some degree of success. Set at 0% then 18 % 35% 50% and then 100% on throttle curve prog. Still achieving full rpm at 3/4 open of stick with last 1/4 of stick travel and last 1/4 carburettor opening adding nothing. Issues also with mixture too! Fine tuning is such fun?

Oh, normal setting on Fatuba 6J for throttle curve is 0%, 25%,50%, 75% and 100%.

Cheers to all, Winco Steve, Sunny 🇪🇸

Denis Watkins30/09/2017 10:23:34
3874 forum posts
58 photos

Just for me

Go to a 16 x 6 for a test Steve

Am engrossed

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