to throttle or not

deanthree5 Mon Mar 24, 2014 7:49 pm

I just finished a lady bug I built from plans off the web.My question is should I throttle it or not? I have a p40 super bee on it now but have other engines that could be throttled. to throttle or not Img_2019

roddie Mon Mar 24, 2014 8:54 pm

Hello there, I would like to see it throttled. Using the engine pictured; you could very simply go with a design like the Ace venturi throttle, designed by Ralph Cooney. They are no longer in production.. but simple to make. A sub-micro/nano servo would be ideal... and would be the only significant added weight to the model.

If you are unfamiliar with this design.. there is some info here:

https://www.coxengineforum.com/t4465-ace-cox-reed-valve-throttle?highlight=throttle

and a video of my demonstration here:

https://www.coxengineforum.com/t5486-049-reed-valve-venturi-throttle?highlight=venturi+throttle

Searching "Ace Throttle" will reveal some more info too.

**RknRusty** Mon Mar 24, 2014 8:58 pm

Edit: Okay, Roddie beat me to it with a more detailed explanation of what I was about to say. But I'll post it anyway.

Dean, that Super Bee probably has SPI which doesn't work well with exhaust restrictor throttles, but if you have one of those needle throttles that regulates the F/A flow through the rear intake orifice, it should work pretty well. If you get a chance, let us see that Ladybug fly.
Rusty

deanthree5 Mon Mar 24, 2014 9:10 pm

Thanks guys, I did not consider the ace type throttle...my real concern was if throttle for this ship was needed?I'm an OK flyer and had heard that this design was quite twitchy, so I question my ability for a successful first flight. RC Plane

**RknRusty** Mon Mar 24, 2014 9:45 pm

I think a big field of tall grass might be your next best bet. Sorry, I'm a CL guy so don't have much advice about RC. I guess your greatest concern is not letting the model get too far away. If you can manage that much control, with a light plane like the Ladybug, a dive into the grass won't bust it up too bad, if at all. If you make it nose heavy, at least at first, it'll be much less twitchy, and you can gradually remove nose weight as you get the feel for it. Maybe some RC guys can chip in with more helpful advice.
Rusty

Mark Boesen Mon Mar 24, 2014 9:45 pm

Hello,
Opinions and elbows, everybody's going to have one or two. I'd go fly it as is, then decide if want to throttle it. I don't think its going to be that fast under power, you could adjust speed a little with different prop. Your not going to have much flight time with the tank you have and then its going to be a glider. Should be a nice little plane!

Mark Boesen Mon Mar 24, 2014 10:24 pm

Couple more thoughts, you probably know this but in case:

Make sure first flight its slightly nose heavy.
Pick a calm day/evening, maybe test glide with radio on into tall grass.
You can add a couple head gaskets (3-4 total) and use a 6x3 prop, or even try a prop mounted backwards.

deanthree5 Tue Mar 25, 2014 6:40 pm

Thanks I think I will fly it as is. I still have to dope the tissue but otherwise ready to go. I suppose just second quessing my ability and needed reassurance from guys whom have never seen me fly HaHa St.Pats Beers

How does the prop backwards affect the flight performance? I have heard of this being done but don't understand how it works.

dckrsn Tue Mar 25, 2014 7:07 pm

Hey deanthree5, late welcome to the forum.
Beautiful build!
Regarding the prop on backwards, it makes
the prop less efficient by cutting the air with
the dull or fat side of the blade instead of the
thin/sharp side(imho). Same pitch, but not as
effective. This also defeats the airfoil shape of
the blade somewhat. Hope this helps.
Maybe someone else can add more info.
Bob

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