Setback

21 posts in this topic

Posted

Got engine mount mounted, set engine on mount, major changes required. Need to move engine forward 4" and drop mount 4".  Would probably be easier to make a completely new mount rather than reworking the current mount. Right now, feel like scrapping the whole thing and either give it up, or buy a flyable one. Will have to head scratch for a few days.

Share this post


Link to post
Share on other sites

Posted

What did you use to jig the mount?  

I spent a lot of time getting the jigs dialed in just right so the prop hub location didn't change when I built the mounts for the 912s.

Share this post


Link to post
Share on other sites

Posted

The mount was a 503/582 mount. According to Hirth the 3202 mounts in the same location as a 503/582, big wrong!  Hirth is a whole different animal altogether. A great high torque engine but, different mounting. Will have to modify this mount or build a new one from scratch. At least I have the airframe and cowling to use as a jig and the proper measurements. This will be a one time item to build. Not impossible, just set me back a month or so and a few hundred bucks. Just one of the problems one faces when trying a new engine system. Been there, done that, got the T shirt and coffee mug, its just been many years since I done it. I'd barnstormer the engine and go with something else but being a stubborn hillbilly and wanting to try this engine I'll struggle onward.  Engine is basically brand new so selling it is near impossible nowdays.

Share this post


Link to post
Share on other sites

Posted

Oh no that Engine mount doesn't work for you. Really sorry to hear that Allen I was hoping I was saving you a bunch of time. I hope you can get it sold and get your money back. You May use this picture to show what it looks like with the 582. That is if you decide to re-sell it.

100_0796.JPG

Share this post


Link to post
Share on other sites

Posted (edited)

The mount isn't the only issue. Evidently my Hirth dealer doesn't know that much. A Hirth will not mount where a 503 mounts.  I may be able to modify this mount and use part of it. The gearbox height is different from a Rotax gearbox so that requires dropping the mount 4" and moving the engine 4" forward.  At least I've got a pattern to go by. I would have had to modify the mount for the Hirth exhaust anyway. I have no regrets on buying that mount so no concerns there.  There is a possibility of turning the gearbox 180 deg to save dropping the mount.  Hey, its all chalked up to a learning experience. Seems to be a vital part of homebuilding. IF, and only if one is willing to learn.

Edited by Allen Sutphin
1 person likes this

Share this post


Link to post
Share on other sites

Posted

In the words of an infamous hillbilly, "I gots me a plan, hey yall, watch this, here honey, hold ma beer."  His last words by the way!  Ordered the tubing for a new mount today and believe I've got a working plan. Rotating the gearbox down will give the 4" drop, now to move it forward 4".

Share this post


Link to post
Share on other sites

Posted

could you have done that with just a new aluminum plate?

Share this post


Link to post
Share on other sites

Posted

Possibly, but the starter lays against one of the mount tubes. The Hirth is a tad wider that a Rotax. Plus having to rework the exhaust system and a new mount will give me plenty of clearance between the fan and firewall. I like a little wiggle room between the engine and firewall. At around 100 lbs engine weight, CG change from going forward 4" isn't going to be a major issue. Being air-cooled, a few inches of airspace around the engine helps a great deal on cooling when its fan cooled. Right now I am still in the engineering stage so things could change, but as of now a new mount would solve several little problems. Gas welding on 4130 was one of the first things I learned in A&P school 40 years ago but need to practice a little before tackling the mount. Good eyes and steady hands aren't what they once was. Getting old sucks!

1 person likes this

Share this post


Link to post
Share on other sites

Posted

I'm curious as to why you want to move the engine ahead. Is this to use an existing cowl or to get your CG correct? I have not heard of any of these airplanes coming out tail heavy.

Share this post


Link to post
Share on other sites

Posted

Prop hub sets about 3" back inside the cowling and the fan intake is 2" from the firewall. A new mount is a lot cheaper to make than a new cowling.

Share this post


Link to post
Share on other sites

Posted

Has anyone designed hub extensions for that engine? I'm just curious because I've seen many hub extensions over the years for many brands of engines. Tons of them used on VW installs in homebuilts.

 

It sounds like you got your work cut out for you. Chopping your cowl down and getting it to look right does sound like an even bigger problem than making a new mount.

Share this post


Link to post
Share on other sites

Posted

A prop extension, to buy one cost more than making a new mount. Reworking the cowling is not even on the table since I hate dealing with fiberglass.  I've worked out the 4" drop by rotating the gearbox down 180 degrees and now working on a plan to slide the engine forward 4" with using the existing 582 mount I bought from TJay,,(well, for the price I paid, he basically give it to me.) Thanks again, TJay. So maybe things are looking better. AK suggested a new alum plate might solve the issue, so I will work with that plan for the time being. I couldn't find a 3/8" alum plate without paying a small fortune for it, so I had a slab of 1/2" alum plate that I can possibly use and with the plate from TJay, things are a little brighter. Went today and checked on replacement welding tanks and thought they was going to call 911 to get my heart started again. Almost $500 just to lease full tanks for one year!  For one small project, it wasn't worth it. BTW, the Hirth gearbox uses the same prop bolt pattern as Rotax.

1 person likes this

Share this post


Link to post
Share on other sites

Posted

I am not sure how big of a hurry your in for the mount plate.  I have the cad files done up for mount plates for the KF and was waiting till the CNC cutter shows up next month to cut them out.  Making the engine mount holes 4" further forward is a snap with the cad..

Share this post


Link to post
Share on other sites

Posted

Right now I am beating a dead horse. Problem #27 raised its ugly head, moving the mount 4" forward puts the top of the engine too close to the top cowling. With the aggravation I feel right now, ready to scrap the whole project. Guess I need to take a chill pill and get away from it for a day or so. A new plate is a breeze compared to everything else. Maybe things will look better Monday.

Share this post


Link to post
Share on other sites

Posted

Not that big of an issue.  Roll the gear box back and drop the mount down like you originally talked about.  Its only metal and with a little time and thought you can make it do exactly what you want it to mr.

:BC:

 

Share this post


Link to post
Share on other sites

Posted

I suppose you are correct!  Might as well bite the bullet and do it. That way all problems are solved with one fabrication. It will only hurt for a little while.  First step, build my jig, then stop crying about it and just do it Maybe a quart of snapper juice to ease the pain.

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Well, bit the bullet and acquired a set of regulators, hoses, and torches. Go tomorrow and pick up the tanks. As long as I have them for a year lease, might consider experimenting with a little wider gear. Don't really need the height, but a tad wider would be good. Might as well make full use of the equipment while I have it. Already have all the materials for the mount and gear.

5 people like this

Share this post


Link to post
Share on other sites

Posted (edited)

Well, welding on the new mount has begun. Gas welding 4130 is slowly coming back to me.  Got the bigger bed made today and to finish welding it maybe tomorrow. Put it in the homemade jig and start on the mounting frame.  Will probably weigh a hundred pounds, I tend to overbuild things. Not a good habit when building airframes. The old rule of "throw it in the air, if it hits the ground, its too heavy to put on an airplane." should still apply, unfortunately it is often overlooked.

Edited by Allen Sutphin
2 people like this

Share this post


Link to post
Share on other sites

Posted

Well, got the basic mount welded up except for one or two tubes that will have to be located after carbs and exhaust are fitted.  Waiting for the next problem to rear its ugly head. Probably mounting the exhaust on the side. At least my homemade jig worked, the mount fit the airframe fine. Forward distance is good, drop is good, so something is going to hose up the progress. I should have expected these problems since this is the first time this engine has been installed in a Kitfox. And as far as I am concerned, the last time.  If 55 hp will get it off the ground, fly at better than 60 mph, then I will be tickled. But I am expecting good performance from it. Most likely it will never be sold due to having so much time and money in it, that I'll never recover the money part let alone the time and work. No sense in being stupid if you can't show it now and then!

Share this post


Link to post
Share on other sites

Posted

Had another little setback with the mount with a couple tubes. A friend who is an engineer came by and solved the issue. Will have to change a couple tubes, but not a major redesign.  But grass season is here so time is in short supply. We need a 36 hour day or two of me!

Share this post


Link to post
Share on other sites

Posted (edited)

Pics, love too see your fab, maybe we can help

Edited by Matthewtanner

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now