Rebuilding the 13B

[Gyro-nut]

Well, I've finally found the time to start rebuilding the '91 13B rotary for my twinstarr

I've attached a few photos in the next couple posts to show the progress so far.

1) Removal of the intake and alternator
2) Removal of the oil pan
3) removal of the flywheel
4) removal of the rear housing

 

[Gyro-nut]

more parts

more parts

1) removed rotor
2) the full monty
3) timing chain
4) oil regulator

 

[Gyro-nut]

a few more photos

a few more photos

1) oil regulator
2) plug
3) misc parts after cleaning... front and rear oil pressure regulators, counterweights, thrust bearings, and spacers

I think there's only one person more upset with having the freezer as my workbench than me... that'd be my wife

 

[RHGraham]

Cool, we were just talking about rotaries in the engine forum this morning...

how do you like it overall in your gyro?

 

[WHY]

Hi Gyro nut

Looking foward to see how that rotary works out on the Twinstarr

Tony

 

[13brv3]

Looks like you're committed now Jim

Do you have Bruce Turrentine's rebuild video? If not, you should pick one up, follow it, and you won't go wrong. I'd also advise using the rebuild kit that Bruce and Tracy Crook sell. The apex seals are the best around.

BTW, any idea what the history of the engine is?

Cheers,
Rusty (been testing the single rotor engine this week)

 

[Gyro-nut]

Randal/Tony, not sure how I like it just yet. The TS is not complete and this engine has never been tested on a TS. It definitely has potential to be a very nice smooth engine with plenty of HP depending on the modifications made. Anywhere from 150-230 from what I've read. I don't plan on making any major modifications to this engine just yet -- some port smoothing will be about it.

I think the only major issues I'll encounter will be that of cooling. These babies run HOT so I'll have to come up with something to keep the temps down. Also, the oil injection has been removed, so I'll have to mix 2-stroke with the auto gas for now. There is a 2-stroke injector available that I may consider later on.

Rusty, Yep-I'm committed alright. Other TS owners are really pushing going with a lyc, but there's already been a lot of time and money put into this engine (ignition system, psru, instrumentation, engine mount) to just scrap it out. If it doesn't fit the bill, then so be it
I do have the video and books from Bruce and Tracy - they are both excellent additions to any rotary rebuild. (gave me the courage to even attempt it) I will be purchases Tracy's seals as well.

No idea the history of the engine, but so far it looks like it has been very well maintained. No major sludge buildup anywhere, no scarring or grooves on the walls. I'll get more pictures once I get the housings cleaned up.

Let me know how that single rotor works out - how many pony's does it put out?

 

[WHY]

Hey Gyro nut

Be sure to use the spiral bead of RTV on the thru bolts to prevent high frequency resonance in these long bolts which causes breaking over time.

Tony

 

[13brv3]

Let me know how that single rotor works out - how many pony's does it put out?

Hi Tim,

Sounds like you've got everything covered. It would be nice to know at least the year of the engine, and whether it was a turbo or not originally. That would tell you what compression ratio you have, and the weight of the rotors. You won't really need to know this, unless you have to replace a rotor, or counterweight.

There's a method of measuring the recess in the face of the rotor to determine the compression ratio, but I don't have it here on my laptop. Good scales of course can tell the rotor weight, which narrows things down a bit.

As for the single rotor, it's still very much a work in progress, though it's behaving better now. It should make 100 HP at about 7500 rpm, which is half of what you can expect for the 13B.

Rusty

 

[RHGraham]

Randal/Tony, not sure how I like it just yet. The TS is not complete and this engine has never been tested on a TS. It definitely has potential to be a very nice smooth engine with plenty of HP depending on the modifications made. Anywhere from 150-230 from what I've read. I don't plan on making any major modifications to this engine just yet -- some port smoothing will be about it.

I think the only major issues I'll encounter will be that of cooling. These babies run HOT so I'll have to come up with something to keep the temps down. Also, the oil injection has been removed, so I'll have to mix 2-stroke with the auto gas for now. There is a 2-stroke injector available that I may consider later on.

Rusty, Yep-I'm committed alright. Other TS owners are really pushing going with a lyc, but there's already been a lot of time and money put into this engine (ignition system, psru, instrumentation, engine mount) to just scrap it out. If it doesn't fit the bill, then so be it
I do have the video and books from Bruce and Tracy - they are both excellent additions to any rotary rebuild. (gave me the courage to even attempt it) I will be purchases Tracy's seals as well.

No idea the history of the engine, but so far it looks like it has been very well maintained. No major sludge buildup anywhere, no scarring or grooves on the walls. I'll get more pictures once I get the housings cleaned up.

Let me know how that single rotor works out - how many pony's does it put out?

Ahh, sorry for jumpin the gun there... I'm a slave to the excitement...
:0)

 

[Gyro-nut]

No Prob Randal... I'm the same way

I can't wait to get this baby running...er... HUMMING!!!

Rusty, it is a '91 non-turbo

 

[13brv3]

Rusty, it is a '91 non-turbo

Jim,

Excellent choice, 9.7 CR light weight rotors, decent size ports

FWIW, while you have it apart, I'd recommend sending the rotors to Performance Coatings for their ceramic coating treatment. I'm convinced that it lowers oil temps, and will never build another rotary without it. It's been a long time, but the last ones I had done were $60 per rotor ($20 per combustion surface) IIRC.

Cheers,
Rusty

 

[Bob]

Boy oh Boy would I ever love to play with all those parts.
never had the opertunity to tear down a Rotory and have alwayse wanted to ! they are such a neet concept !
I've hurd of those engines being use on FW aircraft quite often
perhaps surching FW sites will give you some ideas on the cooling system needed.
...
A great Project Gyro Nut ! Keep up the good work ! and best of luck to ya !

....
Bob.....

 

[Gyro-nut]

Thanks for the advice Rusty, I will take that into consideration since the temps are really the only main drawback I see to the rotary! Any suggestions on where to get that done?

Bob, I've never torn ANY engine down before. I must admit I was a bit nervous, but there isn't much to the rotary (thank goodness). The 13B is used on a number of fixed wings - several RV's that I'm aware of.

Thanks for the well wishes.

 

[13brv3]

Hi Jim,

"Performance Coatings" is the name of the place that's most recommended. http://www.performancecoatings.com/ Their coatings are high quality, and more importantly, they know how to do rotors. They have a jig to protect the sides of the rotor, and the apex seal slots. They also don't cook the coating long enough to melt the bearings.

Attached is a pic that shows a new, and a ceramic coated rotor.

It seems like a new rotary plane flies about every month or so now. RVs and those backward plastic planes :boink: are currently the most popular, but there are certainly others as well. Unfortunately, the cooling system requirements will be so different between a 200 mph plane, and a gyro that I don't think the fixed wing examples will help much.

There's a pretty good email list called the Flyrotary list. You can view the archives, and sign up (very bottom of the page) for the list here:
http://mail.lancaironline.net:81/lists/flyrotary/List.html

Cheers,
Rusty

 

[Gyro-nut]

Hey Rusty... which is which? Mine are caked with 16 year old grime, so I have nothing to compare it too

Any suggestions on cooling for the starr? I've looked at a couple different options, but nothing concrete just yet.
On a good note, I watched a video on youtube yesterday of a rotary with a bad seal being destroyed.... it took the car 10 minutes at 9000 RPM before it started to slow down.... smokin like a motha, but still running

 

[13brv3]

Hi Jim,

There are some folks on the flyrotary list who live to calculate cooling, but this will be a pretty new challenge for them.

Worst case will obviously be high power, slow flight. I think the general rule for slow speed cooling is to use a thin radiator, with as much frontal area as you can fit. Most gyro's mount their radiators right in front of the prop, to help motivate airflow, and I'm figuring that will be a necessity. All in all, water cooling won't be a big problem, since that only handles 2/3 of the heat from the engine.

Oil cooling will be the biggest challenge. 95% of all rotary aircraft guys use stock Mazda oil coolers, because it's proven to work. Most use the 2nd gen (86-91) cooler which is long and narrow, but some use the 3rd gen (93-95 in the US) which is more square. Both are a bit thick to just throw out in the airstream, so getting air to go through them at slow speed is going to be a problem.

If you get tempted to use something else, be very sure it's robust enough to survive the pressure pulses that the oil pump puts out. Fluidyne and Setrab both make coolers that have been successfully used.

The other possibility is to use an oil to water heat exchanger, so you only need one big thin radiator for water cooling. I seem to be one of the very few people who thinks this has advantages, but I've never been accused of being normal My most current test is using an oil to water heat exchanger as an oil sump, so there's no pressure on the oil cooler at all. Ideally, I'd like to build an oil pan that included a water core.

Hopefully, that's enough confusion for now

Rusty

 

[WHY]

Hi Gyro-nut

On your cooling situation, a low speed aircraft even more so than a high speed aircraft needs to have a cooling arrangement that really "SUCKS", it is necessary to create a strong low pressure area behind the radiator or cooler to "draw the air" thru it rather than "push" the air thru it. At low speeds the air just "dams up" in front of the radiator and spills around it and does not cool well.

The radiator usually requires some kind of ducting or channeling to create the greater low pressure desired, naturally your prop is going to be your source for lowering the pressure behind the radiator and cooler, but a little ducting in front and behind the radiator will reallly improve the "suction".

Tony

 

[Dean_Dolph]

Tony, it amazes me that gyros with water cooled engines of any type don't have more trouble than they do since few have any radiator ducting of any type.

The 'suction' you talk about is actually differential pressure. You could have all the suction in the world and if there wasn't difference in pressure between the radiator front and back there wouldn't be any air flow thru it. I'm far from being an expert on radiators but I can see that there is some science involved in selecting one.

I did a quick google and found this info that you guys may find of interest. http://www.tvbf.org/archives/velocity/msg02818.html He even mentions the rotary.

I don't know if this guy knows what he is talking about and I didn't study it in depth. But a quick glance indicates that the Bernoulli principal is in effect. That doesn't mean a lot but points out that the correct radiator thickness and fin density plays an important part in getting the air thru. Just sizing based on fin surface area probably isn't going to work and it certainly won't opitmize the selection.

 

[Bob]

I understand there is a danger in having your radiator too close to the Prop. it seams as the prop comes around it pushes a frontal wave extending a few inches in front of the blade... this wave will beat your radiator to death in a short time... its better to mount the radiator 6" to 8" in front of the prop and have ducting to the prop to pull the air through the radiator... the Ducting can take the Pounding much better than a soft radiator can....
...
My 2 coppers!
Bob........