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Building on a budget - alternative engines for the 701.

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AB_Summit

Joined: 16 Jul 2007
Posts: 23

Posted: Sat Dec 15, 2007 2:33 pm Post subject: Building on a budget - alternative engines for the 701.

Hi everyone,



I'm fairly new to the forum and hopefully soon to be a 701 plans builder. I posted once before about building as a way for a non-pilot to get into aviation and it generated a lot of discussion which I found helpful.



Here's a cut-and-paste of a topic I started over at homebuiltairplanes.com, I'd like to hear from you guys on this topic as well so I thought I'd post it over here as well:



Hi everyone,



I'm quite new to this forum, I posted once before inquiring about plans built 4 place aircraft. However I'm on a fairly tight budget, and after thinking about it for a while I think that the cost of an engine for a 4 place airplane, and the operating costs for a 4 place airplane will be too high for my limited budget. So now I am considering 2 place aircraft.



Let me tell you a bit about myself. I'm not a pilot yet. I was taking flying lessons a couple of years ago, but then I had a snowmobile accident and had to put my lessons on hold and I haven't resumed them. I've got about 25 hours in a C172 and a Citabria though. I've always been interested in planes and aviation and it's always been my dream to have my pilot's license and my own plane. I'm a born experimenter, I love fabricating things and doing things differently than most people, which makes homebuilding a natural fit for me. To give you an example, I basically built my own snowmobile (I used mostly off the shelf parts though), installing every rivet and bolt myself, and then added an automotive turbocharger to the two stroke engine. This involved redesigning the fuel system, exhaust, intake system, ignition, and installing a pressurized oil system to lubricate the turbo. If you're interested in seeing pictures of the project you can click on this link. 



http://s112.photobucket.com/albums/n186/AB_Summit/Snowmobile%20project/



As I said, I'm considering building a 2 place airplane from plans. The aircraft I am leaning towards is the Zenith STOL CH-701. To me the advantages are it's all metal, meaning storage and maintenance costs will be low, and it appears to be quite simple to build, and plans are available for it.



The only big downside to the 701 is the high cost of the Rotax 912, so I've been looking into alternatives to the 912. From looking around on the net, I have seen quite a few different kinds of engines installed in the 701, here are the alternatives I have come up with:



a)the Rotax 582



Pros: great power to weight ratio would give good useful load, cheap to buy, already comes with a redrive, so no engineering/conversion required, motor mount/FWF is available from Zenith.

Cons: two stroke, so reliability is questionable, high fuel consumption, TBO only 300 hours, would need careful attention to jetting, EGT's, etc to be semi-reliable, a little low on horsepower.



b)GEO/Suzuki 1.0L or 1.3L



Pros: cheap to buy, good fuel consumption, cheap to rebuild, can have EFI 

Cons: heavy, would cut into useful load, needs aftermarket redrive, need to fabricate/engineer motor mount/FWF/cooling system, etc.



c)Subaru EA81 or similar



Pros and cons similar to Suzuki but I think the Subaru engine is even heavier so useful load would be minimal.



d)Continental 65 horsepower



Pros: simple, reliable, familiar to aircraft mechanics, no liquid cooling required, motor mount available from Zenith, good fuel consumption.

Cons: heavy, low useful load, might be short on horsepower.



e)VW conversion w/redrive



Pros: cheap compared to 912

Cons: heavy, low on horsepower



f)Corvair

Pros: cheap compared to 912

Cons: too heavy for 701, useful load would be low, performance would not be great due to direct drive.



g)HKS 700E

Pros: cheap compared to 912, lightweight would give good useful load.

Cons: short on horsepower at 60HP.



h)my own home-brewed design: what I'm thinking of doing is taking a Yamaha 4 stroke, 4 cylinder snowmobile engine and adapting a Rotax C gearbox to it to get the RPM's down to where they are usable on an airplane. This engine weighs 118 lbs dry and puts out 140 to 150 HP at 10,500 rpm. I would derate it for aircraft use and limit the RPM to maybe 7000 or 8000, but I think the horsepower would still be over 100. With the weight of the redrive and coolant/oil etc, I think the weight would be slightly more than the 912 but not by much, I would estimate the installed weight at maybe 150 lbs.



Pros: performance could be equal or better to 912, cost much cheaper than 912, good fuel consumption, decent useful load, cheaper to rebuild.

Cons: a huge amount of engineering required (attaching the redrive to the engine, designing an engine mount, cooling system, etc.), unproven design, unknown reliabilty



That's about all I can think of, other than a few other 2 stroke engines that would be similar to the 582 - Hirth, Simonini, MZ, etc.



I'll be using this plane for exploring the great outdoors - scoping out snowmobiling areas, checking out canoe routes, scouting for game, etc. so reliability and useful load are important. I want it to be reliable enough to fly into a remote area without worrying about a mechanical failure, and I need enough useful load to carry a reasonable amount of survival gear.



Am I better off saving up for a while longer and going the proven, factory supported route of the Rotax 912? Or would one of the above mentioned alternatives acheive the same goal for less money? I've pretty much ruled out the Subaru and the Corvair due to useful load considerations, but what are your thoughts on the other options? 



Thanks in advance for your input,

Randy

John75142

Joined: 05 Dec 2007
Posts: 56
Location: Kaufman, TX

Posted: Sat Dec 15, 2007 3:12 pm Post subject: Building on a budget - alternative engines for the 701.

I just started scratch building a 701 myself only a week ago and also am 

struggling with the engine.

I have received a small bit of info from both Great planes and Aerovee.



I have pasted the actual emails I received from them.



A direct drive VW air or water cooled will not perform in the 701.  They 

both turn the same prop diameter.  One does about 215 lbs of thrust the 

other about 260.  The 701 needs at least 360 to do the job.  We have quite a 

numnber of aircooled VW redrives in 701.

Steve Bennett

Great Plains Aircraft





Greetings John,



Thanks for your interest in the AeroVee Engine Kit and AeroConversions

products!



As with all engines, cooling is critical to the AeroVee's long-term

reliability, and we regard the AeroVee's cooling considerations as being no

different from other air-cooled direct-drive engines.



If you are in an aircraft climbing at high throttle settings and low

airspeeds, adequate cooling may be more difficult to achieve and the

installation will most likely need some customization for that mission.



We recommend a fence-type baffle system, such as our Laser-cut Fence

Baffles, to create a large plenum of available cooling air that is not

forced through the engine at excessive velocity such that heat does not

efficiently transfer to the transient cooling air:

http://www.sonexaircraft.com/eshop/cart.php?target=product&product_id=16576&

category_id 68



Note that our Laser-Cut Fence Baffle System is a relatively new product,

which has greatly improved cooling vs. the box baffle system we previously

offered.



If the cowl inlets and exits are appropriately designed on your

installation, this type of baffle system should provide adequate cooling air

at lower airspeeds because, as I mentioned before, lower cooling air

velocities are desirable for the most efficient cooling.



We do not have specific, flight tested AeroVee installation packages for

other aircraft (all of our factory AeroVee installations are on our Sonex

Aircraft airframes). We use the AeroVee/Sonex installation as a baseline

(the AeroVee/Sonex Installation Guide is included with all AeroVee Engine

Kits) and customizations for the unique traits of other airframes are left

up to the builder.



If there are other CH 701 airframes flying (and being adequately cooled)

with direct-drive air-cooled engines such as the AeroVee, other VW

conversions, or engines such as the Jabiru 2200, you will want to look to

those installations for more information about configuring your

installation. We can also offer assistance in looking at pictures or

diagrams of your planned installation for advice and troubleshooting,

however, we can offer no guarantees, as we have never personally performed

an AeroVee installation on your airframe of choice.



As the AeroVee gains popularity, we are counting on the builder support

communities for each airframe design to support one another with successful

installation considerations. As more aircraft of a certain type are built

and flown using the AeroVee, the larger the knowledgebase that will become

available to other builders. We are confident the AeroVee can be

successfully installed and flown with adequate cooling on just about any

airframe. As is the case with any engine installation that is alternative to

the airframe designer's recommendations, however, it may take some

experimentation on your part as the builder to get things just right.



Thanks again for your interest, and please let us know if you have any

additional questions.



Regards,

-Mark

From: John Short <creativesigns(at)embarqmail.com>

Organization: Creative SignWorks

Date: Thu, 13 Dec 2007 14:09:52 -0600

To: <sales(at)aeroconversions.com>

Subject: Engine



I'm currently building a Zenith 701 and have been looking at your engine

package.



---

_________________
John Short

grs-pms(at)comcast.net
Guest

Posted: Sat Dec 15, 2007 3:18 pm Post subject: Building on a budget - alternative engines for the 701.

When you are dealing with airplanes where STOL performance is important, the

amount of horsepower that gets realized as thrust becomes very important.  A

large displacement slow-turning engine will swing a large diameter prop.

Less of the prop disk will be blocked by the fuselage, and a smaller

proportion of the slipstream will be slowed by the wetted area of the

fuselage.  If you can live with the idea of hand-propping, the Continental

65 deserves a good look.



George

---

Joshua

Joined: 05 Nov 2007
Posts: 7

Posted: Sat Dec 15, 2007 3:34 pm Post subject: Re: Building on a budget - alternative engines for the 701.

I'm probably the last guy you should listen too because of my very limited experience. BUT... I am in EXACTLY the same boat as you. I too wanted to build an 801 but Im not so sure I can afford the expenses of a 4 seat plane. On the other hand my financial situation could change in my future and I often think I should go ahead with the 801 for its versatility.

My big question is this- The cost of an 801 kit is SIGNIFICANTLY greater than that of the 701. But what about scratch building cost of 701 vs. 801?

Just wondering if that is something you've considered.

But to stay on topic- Have you looked at BMW R1200 conversions?

They don't get much chat on this forum but they seem to be fairly popular in the UK. I dont know nearly so much about airplanes as most of these guys (really great forum) but I do know motorcyles and the BMW R series is just a fantastic engine. They have a legendary reputation for reliability and seem to me ideally suited for aircraft conversion. Heres what i've found out about them so far-   

           www.microlightsport.co.uk/Catalogue/New/bmwengine.htm 

           www.xairireland.com/conversion.htm

           www.spang-air.de/willkommen/BMW_Engine/bmw_engine.html

If anyone has any experience with this conversion I would love to hear more about them.

              Cheers,

                   Joshua

AB_Summit

Joined: 16 Jul 2007
Posts: 23

Posted: Sat Dec 15, 2007 3:45 pm Post subject: Re: Building on a budget - alternative engines for the 701.

 	  Joshua wrote: 	
		  My big question is this- The cost of an 801 kit is SIGNIFICANTLY greater than that of the 701. But what about scratch building cost of 701 vs. 801?

Just wondering if that is something you've considered.

But to stay on topic- Have you looked at BMW R1200 conversions? 	




Thanks for the replies - Joshua I would love to scratch build an 801, unfortunately Zenith doesn't give us that option. Detailed blueprint style plans that would be required for scratch building are only available for the 701 not the 801. 



That being said, switching to an 801 and buying the kit rather than scratchbuilding would open up a whole new bunch of possibilities for alternative engines, stuff like the bigger Subarus - EJ25, etc... I wonder if an 801 with an altenative engine could be done for almost as cheaply as a 701 with a 912 (both being built from the kit of course.) I'll have to consider that.



I hadn't thought of the BMW engines either, I may have to look into that possibility as well.



George you're right I think the C65 may be a good option as well. The VW's I'm not so sure about.

Tom Lyon

Joined: 15 Dec 2007
Posts: 1
Location: Princeton, IL

Posted: Sun Dec 16, 2007 9:19 am Post subject: Re: Building on a budget - alternative engines for the 701.

Have you looked at the new Verner engines with a re-drive? Similar to the HKS, made in Czech Republic, a little more HP than the HKS.  I hear they are supposed to be a much better setup than the older belt reduction models.



I do agree with George though.  The A65 deserves a good consideration when it comes to torque, RPM and the amount of thrust needed.



Hand propping is not so bad in and of itself, other than the inconvenience.  I have heard from owners of aircraft with hand prop  engines that airport owners are being pressured by their insurance companies to frown upon hand propping without someone in the cockpit.  Not a good idea anyway, but we all know it happens hundreds of times each day.  How far the insurance companies will push the issue is where my concern lies.  Just something to check into is all.  



Tom

_________________
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Guest

Posted: Sun Dec 16, 2007 1:30 pm Post subject: Building on a budget - alternative engines for the 701.

Check out www.ulpower.com.  This looks like a great design.  The downside is (again) cost.  It's expected to cost as much as a Rotax 912.



Dale

  [quote][b]

jetboy

Joined: 22 Jul 2006
Posts: 233

Posted: Sun Dec 16, 2007 2:31 pm Post subject: Re: Building on a budget - alternative engines for the 701.

Randy,

While youre waiting to decide the engine why not get on with the airframe. The scenery keeps changing with engine setups and that decision only needs finalizing before you do the mounts and cowl.



I will add comment on the engines I personally know of in the 701.

1/The HKS never performed enough on the ground to risk flight. It was replaced with a Corvair which climbed tremendously well but the aircraft could not travel anywhere for long other than solo (load and endurance limited) It has been replaced with a Jabiru 2200 which goes just as fast, climbs half as good, but can carry full load the full distance.

2/The BMW 2 cyl. motor didnt work very well and has been replaced by a Rotax 532. This aircraft performs similar to my own 1100 lbs J2200 powered plane, but it is the earlier 960 lbs model.

3/VW air cooled with redrive performed well however overheated requiring rebuild in first 40 hrs. Cooling issues are likely to be fixable, as the cowl was an adapted one not setup for air cooling.

4/912 / 912S these seem to be the engine of choice, cost permitting, although the 912S with the tray mounting is not as smooth and cracks occur to the H stab attachments on models that dont have the updates.

Ralph

_________________
Ralph - CH701 / 2200a

Iberplanes

Joined: 10 Dec 2007
Posts: 174
Location: Igualada - Barcelona - Spain

Posted: Tue Dec 18, 2007 1:24 am Post subject: Building on a budget - alternative engines for the 701.

Great Plains Water cooled at 120 HP should do the job. I´ve read an articule 

from guys at Canada flying with that engine and they are very happy.



If I had a 701, that would be my engine for sure.



Take care.

---

_________________
Alberto Martin
601 XL - Jabiru 3300
http://www.iberplanes.es
Igualada - Barcelona - Spain

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Tue Dec 18, 2007 9:44 am Post subject: Re: Building on a budget - alternative engines for the 701.

Were did you find the article? 

Re: "Great Plains Water cooled at 120 HP should do the job. I've read an articule

from guys at Canada flying with that engine and they are very happy."

_________________
â€œAlways do what you are afraid to do.â€
R.W. Emerson (1803-1882)

"Real freedom is the sustained act of being an individual." WW - 2009

"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune

Iberplanes

Joined: 10 Dec 2007
Posts: 174
Location: Igualada - Barcelona - Spain

Posted: Tue Dec 18, 2007 10:35 am Post subject: Re: Building on a budget - alternative engines for the 701.

Hi Kevin,



It was not an article, it was a website. Sorry for the mistake. 



http://www.culverprops.com/index.php

Take care.

_________________
Alberto Martin
601 XL - Jabiru 3300
http://www.iberplanes.es
Igualada - Barcelona - Spain

Joemotis(at)aol.com
Guest

Posted: Tue Dec 18, 2007 10:35 am Post subject: Building on a budget - alternative engines for the 701.

In a message dated 12/18/2007 9:46:01 A.M. Pacific Standard Time,  kmccune(at)somtel.net writes:

  	  Quote: 	
		  Great    Plains Water cooled at 120 HP 	


 

 I found this website that lists many alternative engines. Quite interesting  reading.

  

 Joe Motis

 do not archive



See AOL's top rated recipes and easy ways to stay in shape for winter.

  [quote][b]

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Tue Dec 18, 2007 2:39 pm Post subject: Re: Building on a budget - alternative engines for the 701.

Joe, I don't see a web address.



Kevin

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