ending the short mount debate...... maybe

[swoeric]

Well im trying to work out the short mount with electrics. here are the thoughts let me know what you think or know.

I have an 85 with electrics and b&c alt.

As i understand it the long mount is 4 inches longer than the short.

The long mount puts 4.5-5 ish inches between mags and firewall

The original starter with pull cable is 1-1.5 inches longer than the mags.

if the skytec starter is an inch shorter the c85 should fit on the short mount

possibly the 0-200 with short alt should fit on short mount with small mount standoffs.

the other idea i was kicking around would be a swing out mount. this could make the distance needed to fit the starter and get the engine as close as possible to the firewall.

so in closing has anybody tried these combos or does anybody have the ability to measure the skytec starter you could measure from the engine flange back

[N-43121]

Re: ending the short mount debate...... maybe

Eric,

I just completed a re-build and went from a short-mount C85 with no-electrics to a long-mount C85 with electrics (SkyTech Starter and B&C Alternator). You are correct, the long mount is 4-inches longer than the short mount. This was done (I assume) to accomodate the older, larger starters and alternators that were available back in the day.

After I bolted everything up for the first time, I was impressed with the room between the accessories and the firewall. I thought it might all fit with the short mount ... so we unbolted everything and tried. I discovered that I would need to make some slight indentations in the firewall (probably 3/4") to allow the starter to fit. Since there is only about 1-inch between the firewall and the nose fuel tank, I decided not to attempt this. It could probably be done, but you would be left with a very tight situation for any future maintenance. I had already planned to fabricate a new cowling (the old one was rather rough), so making it 4-inches longer wasn't a problem. I then came up with a paint scheme that attempted to de-emphasized the longer nose and made it look "stubbier", like the original.

You could solve the maintenance issues with a swing out modification for the motor mount like is done on some of the supercubs. This would require a 337 field approval to do ... but may be feasible. You mention "mount standoffs" ... this would also require some sort of analysis and 337 approval. Are you "experimental"?

I will post some photos of my installation with the SkyTech Starter and B&C Alternator tomorrow. I will take some measurements and post that information as well.

Now ... on a related note. Prior to the latest modifications I made, the aircraft empty weight and balance was aft cg. After my most recent modifications, the empty weight cg is still slightly aft. I was initially concerned about the cg moving too far forward, but it certainly didn't. I find that with the extended mount my tail comes up much easier on takeoff than before.

Hope this helps.

Rod

[Hank Jarrett]

Re: ending the short mount debate...... maybe

Is your plane experimental? Do you want to develop an FAA accepted mod to your firewall forward?

I'm NOT trying to throw cold water on your design changes, I think they are great, but the actual changes will be simple compared to the paper work to keep them. I especially like the idea of the swing out mount! I think it would actually be EASIER than convincing the feds to let us modify our exhaust to let us remove them with the engine on the firewall and working on the back of the engine would be great.

The good thing in your favor is you are in Oklahoma. I haven't worked with the FAA guys there is about 10 years but there were some great guys there. If you don't mind going to Kansas City I know there are STILL a lot of great guys in the Small Aircraft Certification Directorate. Before you cut anything or make any changes talk to those guys. You can even put your plane into a temporary experimental status for testing your mods as long as you can take it back to original. That could save you a lot of heartache if the changes don't work out. You can get a LOT of help from the guys here and if you can get an STC for the changes you may find a tiny market so you won't loose quite as much money (this isn't going to be cheap).

I really wish the foundation had been able to buy the Taylorcraft company. A lot of what you are trying to do would be great fixes for a next generation Taylorcraft (at least how I would have seen it).

Hank

Oh well, we can just buy Taylorcraft from the new owners in a few years if they try to build airplanes. Fastest way to go out of business with an airplane company is to try to build airplanes.

[jim cooper]

Re: ending the short mount debate...... maybe

The swing out is a GREAT idea! My Cessna 195 had it and it made maint.- annual, etc a breeze. It was very easy to swing it. You simply pulled a pin and it swung from the passengers side. I was told this was done as so many were on floats. Whatever, it was a big help. JC

[N-43121]

Re: ending the short mount debate...... maybe

Eric,

Here are before and after photos. I had the C85 short mount with no electrics and went to a C85 long mount with electrics. I will take measurements in the morning and post them separately.

Rod

[N96337]

Re: ending the short mount debate...... maybe

Mine had a short mount, and a generator. There was a very crude indentation of about 1/2" behind the generator and no clearance problems other than that.
I'm staying with the short mount, but throwing the electrics away this time around......
John

[N-43121]

Re: ending the short mount debate...... maybe

Eric, here are the measurements to go along with the photos above:

From the back of the engine working toward the firewall:

Accessory Case = 2-3/8"
Adapter Plate for starter = 1/2"
SkyTec C125T2 starter = 5-5/8" (including 3/4" stub at rear of starter)
Starter to Firewall = 3-7/16"

Rearmost point of Mags to Firewall = 4-1/4"

Rearmost point of B&C Alternator to Firewall = 5-13/16"

Rod

[swoeric]

Re: ending the short mount debate...... maybe

Thank you so much for the dimensions. It looks like there just might be room there with the short starter. The stock starter is over 6 inches. With the short mount there seems to be about an inch between the mags and firewall for the wire room. I am going to try a small standoff that would hold the hinges. it may push the motor a half in to one inch forward from the short mount. may possibly have room if the mount is modified some.

I would ideally like to make a bolt on affair with the swing out option.

SO if anybody has an extra short mount that is not in use let me know, I would be willing to trade out some anodizing or alodine. maybe those of you that have to alodine several wing ribs i can chromic or sulfuric or alodine them in return

[Richard Young]

Re: ending the short mount debate...... maybe

This will not help the long and short mount debate but I'm ready to start a instalation of a c85-12F (with 0200 crank) and I need to figure out what prop to look for! What are you running and do you recomend?

[Eric Tyson]

Re: ending the short mount debate...... maybe

Well it depends on what you want to do, big tires short strips? floats?
I am running a Sensenich 76ak2-39 and a 42 (one for bushwheels other for floats).
It is possable to modify the case to take the good C90 cam, not sure how legal it would be.
Rod is running a 38 pitch with the strait C85.

You can start with the 38 and re pitch it to make the most out of her.
If you are local I could let you try one.

These are climb/ bore propellers.

[astjp2]

Re: ending the short mount debate...... maybe

Eric, did you ever check the thrust line in comparison to the firewall? Is the prop flange parallel or off some? Tim