SparrowHawk Redo

Did you post all the details of your PR system in this thread ? If not I would love to see & read more about it...... Thanks

No not really. I would like to do so now that there is nothing to do but enjoy it. I'd like to take a video of it during pre-rotation. To share and because I've never "seen" it in action. It works well but is heavy and took a bit of doing to get it all together so I doubt you would want to reproduce it. Still, I'll put it on my 'gotta share list' as I like to share this kind of stuff. Could be food for new ideas.
 
Thanks Brock !
 
Double Clutched Mule Drive (pre-rotator)

Double Clutched Mule Drive (pre-rotator)

I'll start a new thread the the same title above for the pre-rotator.
 
Sparrowhawk I rotor head

Sparrowhawk I rotor head

Yesterday I removed and dissassembled most of my rotorhead. Keep in mind that mine is a SH-I head (first picture). There used to be quite a bit of drag in the pitch direction, now I know why. The 3/8" bolt (one with the castleated nut) has just a bit of slop in the center bar that it goes through. Sorry don't remember all the names of these parts. Because of this the nut had been overtightend causing much friction.

This all seemed a bit strange to me so I pulled out the drawing I have for the SH-II rotor head to compare. Seems there are two changes. Bushings (item 16, four are used but only two pictured) replaced the nylon washers that I have on my head. Also a second spring was added to the rear of the head for the slider mechinism.

I was wondering if anyone knows about this change. My question is, were the parts (that the bushing go into) changed before installing the bushings or where they just drilled out for the bushings. I'd like to install these bushings but am questioning the metal has enough edge for drilling a larger hole (just deep enough for the bushing).

Does anyone know about this?

I only saw one response to this issue. Does anyone else have an opinion or resolve?
 
Brock,
I was hoping someone would have an opinion on this subject as I have the same questions and concerns. On my SHI kit there are no bushings in any of the parts that make up the Pitch portion of the rotor head. I feel that the aluminum parts rotating on the steel bolt is not an ideal design. On the SHII and III there are bushings in both the Pitch Pivot Plates (part #320-4006) and the Cyclic Control Bar (#320-4055).

A couple of years ago I asked the customer service dept. at GBA about enlarging the holes in both of these parts to accept bushings. My main concern was that the side (Pitch Pivot) plates only have about 3/8" of material above the hole.. and drilling the hole out to accept a (1/2"OD) bushing would reduce the amount of material to 5/16". I was told that the Pitch Pivot Plates on the SHII and III have the same dimensions as the SHI.. so there is less material above the hole in that part on the models that incorporated bushings. Apparently, load and stress analysis determined that the parts are strong enough with that amount of material (my words).

It was pointed out to me that a bushing may not be necessary in the Pitch Plates if the bolt going through the plates does not move (rotate)... that it is probably more important to have bushings in the Cyclic Control Bar that pitches between the plates.

Newer SH models have bushings in the Cyclic Control Bar... but mine does not. On mine, there is about 5/16" of material below the 3/8" bolt hole in the bar and over 1/2" of material above the hole (seems to me it should be the other way around.. if not centered on the bar). If that hole was enlarged for a (1/2"OD) bushing the material below the hole would be reduced to 1/4"... which is less than the material on the side plates... the difference being that the side plates are 1/2" thick and the bar is 1 1/4" thick.
Unless something changes my mind, I believe I will be enlarging the hole in my Cyclic Control Bar to accept bushings and leaving the side plates as they are. I am wondering why the hole in the bar is not centered... and if it would be a good idea, or a bad idea, to enlarge the hole towards the top side to prevent reducing the amount of material below the hole (if you know what I mean).

On the same subject, I have to wonder why the Roll mechanism uses a 1/2" pin (in a bushing with about 1/2" of material above the hole).... while the pitch mechanism uses a 3/8" bolt. I would think both would be the same (1/2") as they both carry the same load.

Thanks,
Greg

This was the response.
 
I don’t see any tension pulleys in your prerotor belt, (pic #1)
You might add some as they help keep the wear down.
Maybe ask Brad or Mike B. what they used on their SH.
This picture is from my RAF
Your build looks nice.
attachment.php


Does anyone have part numbers and source for these tension pulleys for a Sparrowhawk? I'm sure the RAF would work as well.
 
Right now I don't have it installed. I managed to break the mount some time ago and never put it back. Turns out the hole in the front makes an excellent handle for ground maneuvering.

Sorry I don't remember which light I have. I could go take a look but why bother, it was expensive and I'd probably use something different today. But if you want I'll go look anyway.

Regards,
 
Brock, Do you or some other Sparrowhawk owner have a picture or drawing you could post on how the anti-servo is hooked up on the tall tail. I did a SH conversion on a RAF but had no drawing and dont want to do it twice. Thank you. You could also call me with details. 610-370-2178. Thank you
 
Hi, Brock. I see you have the SHredo for sale on barnstormers. I was very interested in reading the rebuild as you progressed. I am curious why you have decided to sell the plane so soon after finishing the rebuild? I saw you were having problems with the belt drive reduction unit, and see you have installed a gear reduction unit from Autoflight. How is that working out?

Cheers,

Dave
 
Hi, Brock. I see you have the SHredo for sale on barnstormers. I was very interested in reading the rebuild as you progressed. I am curious why you have decided to sell the plane so soon after finishing the rebuild? I saw you were having problems with the belt drive reduction unit, and see you have installed a gear reduction unit from Autoflight. How is that working out?

Cheers,

Dave

Sorry Dave to be so loooong in seeing this post. I've been absent from the forum for awhile. Good question with an easy answer. I've got too many aircraft to both fly and maintain. That's the short answer.

The long answer is that I'm almost done with the restoration of a McCulloch J-2. Plan is to fly that for a bit and eventually purchase the new tandem that sportcopter is working on. Then the J-2 will be looking for a new home. I've also two fixed wing acft. One of which I want to sell but it's involved in a lengthy STC project. Once that's done the plane will be sold.

The Autoflight gearbox is really nice. I never have to give it a second thought as for reliability. The belt system I never trusted.
 
Thanks Vance for your input. I spoke to a fellow in CAN (Ross from SDS) who says he has 350 hours on his subaru powered airplane and has not had any problems with the heat removed. Seems the only issue would be in sub zero temps with visible moisture. Then there would be impact ice. Nice not having a venturi.

So with this issue put to bed I got out the power tools and made some reductions on the throttle body.

Formula: 1stPic - 2ndPic = 3rdPic

Now it looks like an aircraft throttle body.

The last picture is to show what I did with the linkage. These are removed parts just installed differently. The Pin on the left was removed earlier then I drilled and installed it to make the open position throttle stop. What was the open throttle stop is now the idle screw.

I just might have to do this.....
 
Brock.......please come back here, we need you & your skills ! How"s the J2 coming ?
 
Brock, WHERE ARE YOU ???!!!
 
CLS447;n1122803 said:
Brock, WHERE ARE YOU ???!!!

Sorry for being absent these past months. I've just been too busy with too many projects and other responsibilities. Looks like I'll miss the next (AUG19) chapter meeting, again. I leave, soon, for a crazy 10 day bicycle ride from Missoula to Vancouver (WA). I consider this a once in a life time event.

Projects:
--The SHredo has been grounded for the past year due to low compression on one of the cylinders. Don't know when I'll have time to pull the engine. I think I'd sell it if someone made me a reasonable offer.
--The J-2 is all but done. Only lacks a day or so of work but then many hours of paperwork. Can't seem to get it finished. I'm not sure I really want to fly the j-2 anyway since they are getting rare, it belongs in a museum.

Anyway, I'm around. Feel free to drop me a line for those of you (PRA73) who have my #.
 
Brock, I would love to see some pics of the J2 ! Have a great time & be safe on that bike ride.

Do you think it is a ring or valve problem with the Subaru ? Can't you just pull the head without removing the engine ?

I need someone that is full of SH info. I have a friends SH1 kit here that we are trying to finish. Your assistance would be great !

Thank You !
 
Hi Guys, I am looking in to what improvements could be made to make the SparrowHawk better? After looking in to it, I am good with the tall tail but will agree that Toe Brakes are a must.

Any Ideas?

Thanks,
Dakoda
 
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