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Blitz Helicopters Avro 90 > Elevator Servo cutouts

marked23
Veteran
Location: Lynnwood, WA

The instructions cover putting on the servo arm after intalling the elevator servo.

If you put the servo arm on ahead of time, like I did, you'll find that the servo doesn't fit through the cutout. And since I'm using 8717 servos, once those servos arms are on, they are there to stay. So I carved up a bit of the frame to make room to slip the servo arm through the back cutout. It didn't take much.

Maybe Blitz could change the frame design at that little spot to accomodate a pre-installed servo arm. There's already a notch for the output spline. Just adding a generous chamfer on those corners would do the trick.

-Mark

05-07-2008 08:38 AM

Matutu
Heliman
Location: Torquay - United Kingdom

Yer mark I had the same issue as your self, those 8717's are a nightmare with the blitz horns, once these are on they are on for good. I managed to get the elevator servo attached though by coming through the top and gently flexing the frames (VERY gently).

Seeing your using 8717’s I will be very curious to see how much Sub trim you needed as on mine nearly all 3 servos required 90-120 sub trim to get them centred.

Also do you find even when the servo is centred the elevator link, runs very high on the swash. I mean because the elevator arm is fixed because there is no link to adjust to the swash, I found I needed to alter all the other links to suit this and move away from the manual to get the swash 100% Level.

Matutu

05-07-2008 10:22 AM

HOMEPAGE

dannyh5
Senior Heliman
Location: England

Firstly unless you have welded the servo arm on you should be able to get it off.

I have had a similar problem with a t-rex, I thread locked the elevator servo arm on and couldn’t get the thing off. When I needed to get the servo out I ended up drilling the bolt out of the servo, but that’s tough sh*t. The heli is designed to have the elevator servo installed without the arm and the arm is put on after servo installation. I’m not going the ask Align to put a big star shaped cut out in the frames so I can ignore the instructions and build it how I want.
Someone who knows what they are doing has written the instructions in such a way that you don’t have problems building the heli, why don’t you follow them?

Someone who knows what they are doing has written the instructions in such a way that you don’t have problems building the heli, WHY DON’T YOU FOLLOW THEM?

05-07-2008 10:32 AM

HOMEPAGE

stanc
Veteran
Location: Conroe, TX

dannyh5
Do you repeat yourself often? Do you own and or built an Avro 90, if is your not very proud of it since it isn't listed in your profile. If you've not built one, then you have no idea what these guys are talking about. Unless you have something constructive to say then go back to the Align forum and beat up on those guys. Until now we haven't had the usual RR bashing here in the Avro forum and I for one would like to keep it that way.

Stan
Will Work for Electrons

05-07-2008 12:54 PM

dannyh5
Senior Heliman
Location: England

I do have experience with the avro, and I will repeat myself again. Read and follow the instructions!. I will have a word with Dave Fisher at the next meet and ask if he can get the servo installation put in twice just for you.

05-07-2008 01:06 PM

HOMEPAGE

Matutu
Heliman
Location: Torquay - United Kingdom

Thanks Stanc.

dannyh5, I gather you have not got a Avro, and therefore have not used the blitz metal servo horns. The blitz metal horns are specially for JR/Futaba servo's and you can order different ones for the servo’s which you are using.

On most JR servo’s the horns fit lovely like my 8900G etc, but on the 8717 it does fit extremely tight and they only way to fit them on is to use some sort of clamp or a strong screw. Now when you do this you have to get some angle on the thing so therefore if you were to put the servo in the Avro first you would never get that servo horn on especially ones you get the servo cams and everything else in your way hehe.

Mark did one way of doing it though of putting the horn on first (the only way) and then filed the frames. I managed to put the horn on first then gently ease the frames apart and come in from the top so I never filed down my frames.

Blitz have told you in their manual how to do it there way of putting the horn on after, but unfortunately it seems that JR manufacture the 8717 with a different type of spline and therefore its abit tighter on the 8717. Also you can remove the horns but this is abit of a effort because they are so tight.

Matutu

05-07-2008 01:08 PM

HOMEPAGE

AreA51tje
Senior Heliman
Location: Murcia, Spain

Have the same problem with the BLS351 and BLS451 Futaba Servos. The arms fit really tight on it and its imposble to take them off by hand so i produced a home made extracter tool to do so. I dont know, seems that some servos have slightly bigger spline then others. the BLS251 is fitting perfectly. very strange...

But offcourse its a nice job to take of the support etc of you want to adjust the servo horns.

I used some Sub trim on my avros on the servos and there perfectly centered at 90degrees. ¨

Does the end trim really effect you end points on a servo?

Regards, Dave

05-07-2008 04:38 PM

HOMEPAGE

RyanW
Veteran
Location: Stillwater, Oklahoma

Dave, I am going to experiment with the sub trim vs endpoint today.

I fit the servo arm on before installation, because I matched them prior to installation and they are impossible to remove without buggering up the servo case or using a special puller.

It was very tight and I had to manipulate it for a while, but I did manage to get the 8717 in there.

05-07-2008 05:11 PM

HOMEPAGE

marked23
Veteran
Location: Lynnwood, WA

Matutu,
I used RyanW's suggestion of swapping servos and horns around until I found the closest match. I ended up with subtrims in the 30s. (For comparison, when I build my Fury, I can keep testing alternate splines forever and have zero subtrim every time.) Nevertheless, I ended up with very minimal interaction. I use the MA swash plate leveling tool and check the swash for level at low, mid, and high positions. I didn't have to mess much with the endpoints to get everything straight. (About the same as the Fury... even with zero subtrim, I would still have to mess with endpoints.)

Dave,
I would like to see a picture of your extractor tool.

>Does the [sub] trim really effect your end points on a servo?
This would depend on the radio. I'm interested to hear the results of RyanW's experiment.

-Mark

05-07-2008 05:33 PM

kirk
Veteran
Location: Thornton, Colorado

You can always discard the nice arms that the kit comes with and use plastic arms like you would with a MA or Align machine. Then again since the JR plastic arms only have two sides to them you will probably use a little bit of subtrim with them as well.

By swaping mine around a bit I got two of the really close, and 1 servo required about 23 cicks of subtrim. I am using a DX7 and I have not noticed any interation issues with that amount of subtrim in the radio.

Kirk

05-07-2008 05:53 PM

stanc
Veteran
Location: Conroe, TX

Here is a quote from another forum.

Quote
There is a bug in the JR/DX line where if you use too much subtrim & activate EXP function to get rid of interaction you get this effect. Solution is to re-do the servo wheel with minimum subtrim.

I'm using a DX7 and have a maximum of 30 for one sub-trim and don't see any interaction, all the end points are set at 100.

Stan
Will Work for Electrons

05-07-2008 05:58 PM

marked23
Veteran
Location: Lynnwood, WA

Kirk,
Good point. I would have used my plastic arms if only I had some ball link balls that would fit plastic servo arms. Part MA0103 would do the trick, but nobody had them in stock when I needed them.

Does MU stock this part?

-Mark

05-07-2008 06:02 PM

kirk
Veteran
Location: Thornton, Colorado

No MU does not stock MA parts but I have some spares from my MA days at the house if you want some. If you want them send me you address in a PM and I will send them to you...

Thanks!!
Kirk

05-07-2008 07:05 PM

AreA51tje
Senior Heliman
Location: Murcia, Spain

Marked, when I get home will make you a picture of the extractor tool I have fabricated by myself.
REgards, Dave

05-07-2008 07:08 PM

HOMEPAGE

marked23
Veteran
Location: Lynnwood, WA

Oh whoops. sorry Kirk. I meant to ask if MU stocks the control balls that are used on the Avro throttle linkage. These are the ones I would really want if I could get them. They aren't listed on the Blitz web site and I don't have my manual in front of me to figure out what the part number might be.

-Mark

05-07-2008 07:23 PM

RyanW
Veteran
Location: Stillwater, Oklahoma

Not that any of you need any more advice, but I would be cautious in using the 2mm thread bolts for the cyclic servos. I had those come loose and I actually broke one on the Synergy.

EDIT: (the N9 steel isn't the same as other steel)

This was my fix- Servo Arm Mod

You have the same issue with finding center, but it is was a much better option than loosing the machine! As you can probably tell, I was thrilled to see the Avro using the same style that I had to fabricate for the Synergy.

05-07-2008 07:48 PM

HOMEPAGE

kirk
Veteran
Location: Thornton, Colorado

Hey Mark

Sent you a PM...

Thanks!!
Kirk

05-07-2008 08:31 PM

AreA51tje
Senior Heliman
Location: Murcia, Spain

Ryan, did you tested allready?