Putting a VIKING Engine in an S7 Courier



In addition to the original Viking Engine group:      http://groups.yahoo.com/group/Vikingaircraftengines/

A new one has started which is not censored by Jan. Worth looking at:     http://groups.yahoo.com/group/Viking_Aircraft_Engine/


The Viking/Honda looks like a possible alternative to the 912S Engine. It is less than 20lbs heavier (maybe), is fuel injected, uses a stock automotive block and really looks nice!  Jan Eggenfellner says it is $10000 les than the Rotax alternative but in the S-7 environment, at current prices from Rans of $21,000 for a new 912S and firewall forward kit (17+4 as of 2012/09/20), it looks like it is about $5000 less. For about $16000 Jan offers the engine, fuel pumps (pre assembled package), wiring harness, header tank, motor mount and cowl; these last two items are not yet in production for the Rans.  For another $2800 Jan will do the whole installation. It sounds very appealing.


I started discussions with Jan and sent him some info my S7S. Below are the areas I thought he might need:


First, Weight and Bal measurements

One of the first tasks I wanted to do was plug the Viking numbers into my S7 weight and balance spread sheet. I thought Jan would also want to do this especially if I were to hire him to do the installation so I sent him the following material:

_                ____|__|_____|_______|_____________|________|_______|_________|________|


                         P   E        Datum        G                        B1          B2              BY                Short   S + Long

                      -29.5   -17     0               34                         81.5          110            140/142               208           230


Stations are:   Prop,   Engine,    Datum, Main gear,   Forward/aft Baggage station    Battery station/cg     Short tail    Long/S  Tail wheel 

Engine CG is approximate (engine and prop, without muffler was about level when hoisted at the lifting pad).

The prop hub measurement of -29.5 is from Rans but I see 29” on mine plus a 1” spacer putting the prop at -30”


All models of the S7 (short tail, long tail and S) have the same moments from firewall (D) to Battery (BY). Only firewall itself (and forward of firewall) and aft of battery are different.


CG range:  46 to 51

Typical empty Cg is 49”; Most fwd (low fuel, 220 pilot) 45”


I also sent Jan measurements for the S-7S firewall forward which I’d obtained from Rans.


My early S7S has a heavier cowl (15.4lbs vs. 11 stock) larger oil cooler, thermostats and cabin heater and empty CG is  47.9”

Oil canister is on firewall (dry sump engine).


Spinner is 12”




Jan thought that he might move the Viking back a few inches but could put in a 2” prop extension. He never said where the CG of the Viking engine is however my rough estimates and adding the header tank gave a minimal CG change. Jan didn’t seem too interested in the actual weight and bal numbers just how builder’s models have worked out. He said:

I am more interested in the general knowledge between builders, as if the airplane tends to end up tail, or nose heavy. Or right where it needs to be. 




The throttle control quadrant on the courier connects to dual bicycle cable/spring return at the carbs.  Does Viking use a push/pull control?  Yes



Fuel system:


Fuel line routing on this and earlier S7 models has tank exits at front and rear of each tank. These 2 lines from each tank are Y’d together part way down B1 to get one line per tank and Y’d again at base of B1 to one line going forward.


Later S models have the forward tank outlet going down the forward door post to a block below the pilot where front and rear are merged. Both then have the fuel shut off just ahead of the pilot seat. Mine has no electric fuel pump just the engine driven pump; later S models have a fuel pump and gascolator on the firewall.


The baggage compartment is defined by a cloth sack. There may be room below at either baggage station for the header tank.


The header tank holds 2.5 US gal (15lb) plus weighs only ?lbs. It could be installed at the 110” station.




That is the stock coolant rad angled down ahead of the firewall. My cowl is a little deeper there than stock and the rad covers most of the air outlet area so that most of the air coming in the top nostrils and from the oil cooler exits through the rad. The later S models have the rad horizontal and a little higher with no baffling to get most of the incoming air to exit through the rad. Some folks have added some baffling to encourage more air through the rad.


Jan’s package has the rad forward below the engine which may result in a pudgier cowl. Possibly it could be moved back closer to the firewall.



Current battery is an Odyssey (680?) at -142. It could be moved back to the next station at -170:



and looking forward:



and aft:


Without doing any calcs, Jan thought that the existing battery location was good.


Mount construction

The Viking stainless mounts look exceptional but I wonder about one design aspect.

Paul Lamar is a guy in California who has been active with Mazda rotary engines. He is self taught but has a lot of engineering skills. His write up on design of motor mounts points out some key design criteria and is worth reading.


Paul’s main point which, I understand, is a legitimate engineering rule of thumb is that all members in such a structure should be in tension or compression and NOT see a bending force. He concludes with:


If these rules are violated the motor mount might still work but it is nearly impossible to predict the stresses and deflections without FEA and therefore these kinds of mounts are extremely dangerous. They may crack without warning.


 It appears that many of the Viking mounts disagree with his approach in that they do not have multiple tubes converging at a point and frequently have cross braces meeting another tube not at a cluster. This is one example:


Paul would disagree with this design. Is he wrong?  Jan’s response:


Yes, wrong.

The cross bar does not contribute to holding the engine.  It only allows for the 2 top rubber dampers to share the load equally.  


We will not build Viking engine mounts to anyone else's specifications.  




Sounds like a load which is applied mid span which others feel is a no, no. Also it looks like that tube that does hold the engine has no other support.



So, finally, before firing off my $8000, 50% down payment, I took a look around the net to learn more about Egenfellner and his previous products.


I did some searches to see what all was out there on Eggenfellner engines. Turns out there are unsatisfied customers from his Subaru days and the reduction drives he designed for them. There have been accidents and at least one fatality with one of his engine/redrive/prop combos where Jan played an active role in the installation and testing of the engine. There are claims of paid for but unshipped items. OK, but this was years ago and with a different product so I was still willing to consider the Viking but maybe not as an outright purchaser.


As a result of this info, I sent Jan this note:


Hello Jan.

What I've decided is that getting a Rans S7S flying with one of your engines would be of as much benefit to you as it would be to me. Further, there is no doubt that with so few hours on the engine in any airframe, I am taking some risk in setting aside my proven 912 and going Viking.

I would still be willing to make one of my S7 airframes available for a Viking and aggressively put time on it but not with me footing all the cost.

If you would like to participate in a cost sharing arrangement, let me know.



Jan replied:


Not interested.  

Thank you



I then sent a note outlining these thoughts to the Rans Flyers and S7 yahoo groups. One person then forwarded my note to the Viking group. Jan actually posted it for a couple of hours and did reply to the financial part of it but then removed it from his group. It was message number 2443 and did include my questions on the mount design and a suggestion that there are dissatisfied customers from his other product offerings. You can see his response in message 2444.


Since first airing this, several people have pointed out info on the net about Jan’s level of success with his previous Subaru ventures and some of the accident reports related to Eggenfellner powered aircraft.


Apparently Jan does not feel the need to talk to these issues now nor to deal with any subject matter that may have a negative reflection on his product.


Nevertheless, many of us hope that Jan has resolved the issues that were a problem in the past and that the Viking thrives.




Issue number 103 of Contact magazine has some comments on Jan’s creative history and an evaluation of some design flaws in his earlier drives which may still exist in his current offering (granted listed by a competitor, now deceased, Bud Warren); these include: type of gears, bearings, lubrication.  The title of the article is: “Eggenfellner Gearbox Problems? Meet the Alternative”.


A couple of days ago Jan put out three youtube videos in which he tells his life story focusing on his involvement with auto conversions. He is candid enough to mention that not all of his offerings were successful, attributing some problems to trying to go for higher horsepower engines. I sent a note to the Viking group congratulating him on his openness in the videos but went on to suggest that maybe he could add to his credibility by getting some expert engineering evaluation of his drives, couplings and electrical system.


He did not let the message get posted nor did he reply.


Next I sent him this note and also got no reply:


From: Peter Cowan

To: Jan Eggenfellner

Sent: Friday, October 05, 2012 9:40 AM

Subject: Just a suggestion


Hello Jan.

You are proving the claims that you do not want to talk about any issues you feel are critical of your efforts and that is certainly your option.


What is curious though is that you then go and publicly admit on Youtube that you have produced products that were not successful. Why would you do that without then going on to concretely show how you have addressed and fixed those problems? This defies logic.


Take a look at what Bud Warren said about your drives in Contact magazine issue 103 (issues are ball bearings, spiral gears and poor lubrication)

and make the effort to demonstrate technically how you have fixed this; or, alternatively, stick your head back in the sand and say nothing about past failures. Unfortunately, with the web, what you have said and done will always haunt you, forever.


Just a suggestion



You can read the Contact article here:   http://issuu.com/panzera/docs/issue_103-teaser     and go to page 4 and 5.


This is a video of Jan presenting at Oshkosh:    http://www.youtube.com/watch?v=01ysT07YH18




Near the end of October, I received a request from Samantha to pay my 50%. I explained what had happened and suggested she encourage Jan to deal with these issues.

She did reply that Jan agreed to reduce the price for my S7 installation by $1000. I told her that now, money was not the issue but rather getting some technical info was more important.