SparrowHawk electric trim

[paulp]

Hi Greg,

I'm using the 6"-100lb+with a 1"/sec rate of travel. I would, however, recommend using a rate of travel of .3"/sec as it will give better control and finer adjustments and eliminate several small adjustments to get the trim where you want it.

 

[MichaelBurton]

We used the Firgelli with a 6" travel and the slowest speed. I made the left right trim switch run one up and the other down at the same time and the pitch switch move both up or down together.

 

[Colin Gibson]

How much trimming is everyone having to do in your Sparrow Hawks. I have flow nearly 100hr in mine and find it unnecessary to trim from single to duel occupant at all. For me it seems the extra power required to fly straight and level with two accounts for whatever trimming would be necessary from single occupant and I haven't had to touch it apart from pre-flight checks.
It will fly hands off also so I cannot understand all the fuss in an expensive electric trim system.
Colin

 

[willisbr]

Paul can you shoot me an email on the actuators you used as well? I want to start looking into installing mine for electric roll adjustment. Not sure if RAF uses the same actuator size for both pitch and roll.

THanks.

 

[paulp]

Hi Brian,

See my post of 11/14- I am using the 6"-100 lb 1"/sec units. I recommend the same unit but with the .3"/sec rate of travel. Both my pitch and roll are interfaced with and operated by an RC Allen stick grip with a 4 position coolie hat switch.(it also has a trigger switch for the radio-the stick grip is about $200 from RC Allen) There is an opposing spring and the actuator is used to counter that spring.

Any other questions let me know.

 

[bmoore2156]

Here is what I am working on..

I ordered 2 of the 6'' stroke actuators here. They are the .33'' per sec.
https://www.firgelliauto.com/product_info.php?cPath=67&products_id=1

I found these 4 pole relays for cheap on ebay. You will need 4 of them if you are planning on running a 4 pos hat switch from the cyclic. I will make a wiring diagram and post it later... should be real easy.
https://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400090769192&ssPageName=ADME:B:EOIBSA:US:1123

I am using a Flight Grip for my cyclic. It has a trigger that I use for the radio. I ordered a new top cap that came with a push button and a hat switch labeled for trim.. (U, D, L, R) I will hook up the push button for radio channel flop.
Aircraft spruce has them here...
https://www.aircraftspruce.com/catalog/elpages/pistolgripswitches.php
I had to call them and ask for the switch because spruce didn't have them listed.
You can order directly from them (cheaper) here.. Just the switch itself was $60 or so.
https://www.manta.com/c/mmnkhdh/flight-grip-llc

My next mission is to find a spring that will work good... I have seen people use the drawbar style spring. I really like this because the spring can't come loose with slack... I am still looking for the right tension and lenght...
I have found them here.
https://www.centuryspring.com/pdfs/338.pdf
And ideas of length and tension?
Thanks,
Brad

 

[bmoore2156]

I found another source for drawbar springs.... Help me out guys.. which one???
https://www.grainger.com/Grainger/w...g&op=search&Ntt=drawbar+spring&N=0&sst=subset

P.S. I can get about 25% off from Grainger stuff from work.
Brad

 

[route66]

Brad, I used the same actuators and found them to be too fast and added resistors to the power input to take about 2/3 of the speed out. Still has enough power and is at a slower more manageable speed.

 

[bmoore2156]

Brandon,
That sounds like a great idea. I will see how well they work and then may install resistors if needed.
I really want to be able to fly it with the trim if at all possible. It will be a redundant control system. If it moves to fast for that, I will slow them down.

My good friend sent me the part number that Sparrow Hawk lists for thier trim spring.
Gardner Spring 882c

I found them on the web and he said they won't sell small quanities. He gave me the Grainger number. I will order them today.
Here is the Grainger #
Steel
https://www.grainger.com/Grainger/Extension-Spring-1NBR6?Pid=search
Stainless
https://www.grainger.com/Grainger/Extension-Spring-1NBU1?Pid=search

If anyone needs them and doesn't have (or can't get) a Grainger account, let me know and I could have them drop shipped to you.
Brad

 

[bmoore2156]

Relays

Relays

I got the relay cubes and bases in the mail the other day.
I really didn't like how much the bases weighed. I also didn't like how much room they were going to take up.
I decided to solder the pins on the bottom of the relays instead of using the bases. I made a base and poured it full of epoxy. This will keep moisture out and electricity in!
I also used the molex plug so it will be "Plug and Play"
Heres a pic.
Brad

 

[Tbrewster70]

Stan,
These images are from this last summer's Oshkosh. I believe they may be Tom Korrison's Sparrowhawk (TKorrison), and might be based on Alexander Lameko's design (twistair). I too am planning on electric trim, but I have not decided on a design.
Heather

Do you have any contact information for Tom Korrison? We purchased a Sparrowhawk he built.

 

[Kevin_Richey]

Tbrewster70: That post (#3) you quoted is from way back in 2005. The person who wrote it hasn't been here on the forum since 2014.
You might have success finding out her contact info from an internet search w/ her name & city/state location in order to ask her.

 

[Tbrewster70]

Yeah I figured it was a long shot. Thank you