Rear intake Discovery or Stalker

[frank williams]

I know I've seen pictures of a rear intake stunt motor, either Stalker or Discovery or some such.  Does anyone have a link to one of these motors?  I know I've seen one that is front intake with the intake on the "bottom" of the shaft, although I don't know which brand that is.

[Brett Buck]

I know I've seen pictures of a rear intake stunt motor, either Stalker or Discovery or some such.  Does anyone have a link to one of these motors?  I know I've seen one that is front intake with the intake on the "bottom" of the shaft, although I don't know which brand that is.

   That was a Sergei Belko engine, I think.

    Brett

[frank williams]

Yes, I think you're right.
.... I found this one, but I think there is a rear intake one also ....

[Randy Cuberly]

Yes, I think you're right.

Hi Frank,
I've seen a number of Belko engines in fact I own several.  However all the one's I've seen were not rear intake but were rear exhaust with the intake in the front but inverted 180 degrees on the shaft. Like these two of mine in the picture.

There were some rear intake stunt engines made in Europe in the 90's but I can't remember right now what they were called.

[frank williams]

Thanks Randy
Have you much experience running these, and how did you mount them?

[Randy Cuberly]

Thanks Randy
Have you much experience running these, and how did you mount them?

Hi Frank,
I've had a fair amount of experience with them as in two airplanes both Geo XL's.

They are excellent running stunt engines when used with NO Nitro fuel and in a relatively light airplane.  My Geo XL at 710 sq inches weighed 54 oz.  The engine with muffler attached weighed only 10.5 oz and that of course contributed greatly to the low weight.  They are very quiet smooth running engines with a good amount of torquey power.  As with most East European engines they are intended for relatively Low RPM operation.  The prop pictured with the engines is also of Belko manufacture and is an 11.5-6.5 that is also very light an is carbon fiber over white foam.  I never ran them on anything but these props  (I have 4 of them).

The mounting is unfortunately the only EVIL thing about the engines as it requires a long crutch be built to support the front mounts and the rear mounts in a nice flat plane!  Certainly not all that difficult to do but somewhat of a Pain in the You know what!  I made laminated maple and carbon mounts and cut them to contour to accept the engine.  The GeoXL was an excellent flying airplane with this engine and in fact I keep poking myself for not building another one for the engine on the right in the picture.  That engine is a .61 the other one is a .56.  The airplane in question was powered by another .56 just like the one in the picture.  Unfortunately it and the airplane were stolen from the flying field about 6 years or so ago!

The photo below is of my GeoXL with Belko .56 installed.

Incidentally it used only 4 oz of fuel to fly the pattern.



Randy Cuberly

[Dave_Trible]

Frank don’t know if this could be what you might be thinking of-  Tono.   From Prague in the mid to late 70s.  The two on the right are 10 cc and the other two are 5.6.

Dave

[bill bischoff]

You could always make a rear drum valve version of a 40 or 46 VF...

[Dave_Trible]

There is an engine called SKIF, a 9.5 and a 76 that I can't find any pics of that MIGHT be rear intake.  These are of recent make. They stand out because they look extremely tall.

Dave

[Massimo Rimoldi]

Goodmorning everyone.
Only to expand the archives: one of the first DR by Yuriy Yatsenko

Regards, Massimo

[frank williams]

Thanks for you inputs …

Dave ….. I’ve never seen that motor before ….. 10cc is a sizable motor … interesting construction for sure

Massimo …. Looks like a shorter shaft version of the ones Randy has shown … Do you know in what configuration he (Yuri) ran the motors …. Which way was the cylinder pointing, …. Down, outboard, or inboard?

Randy …. The “algorithm” is very nice .. I assume by the cown and standard nose that you ran the cylinder pointing down.

Bill …. “been there done that” ….. I ran an OS VF 46 in 1992 and numerous years after that …. It was a confab of the regular VF and a pylon crank and rear intake.  I also ran it as a front exhaust on a pipe.  It ran great for me. 

The front exhaust makes sense to me in that it gets the hot part of the motor facing the wind. 

The rear intake makes sense in that you get a shortened fuel flow, less head loss in the line.  Additionally, if you want to stuff the crankcase of a motor, there is no better way to do it than to eliminate the volume down the middle of the shaft, it’s huge.  In general stunt motors could eliminate a lot of weight by going rear intake.  The massive crank used today could be replaced with an 8mm shaft and a lite housing for the bearings. 

The inboard cylinder makes sense in that I have convinced myself that the extra 3g’s helping to keep the plug free of excess oil was a good thing to do.  The transitions in the eights are very benign. 

However, all these things make nose construction a bit more difficult.  Anyway, I thinking out of the box again.

[M Spencer]

Theres the MVVS 40 / 49 RVs ,

plus others .

This Guy has some wierd stuff .
https://www.ebay.com/itm/Very-Rare-Vintage-Russian-9cc-Stunt-Engine/183206235185?hash=item2aa7f14c31:g:D~8AAOSwcUBYRY5t

Russian 9cc RV stunt glow engine.
This F2B engines were produced in USSR back in the 80's by Valerii Patsuk.

[M Spencer]

Theres a OPS Rear Intake set up . Super Tigre RVs in 21/40 & a rareas 21/51 . Theres at least ONE made .
HP 40 in the R P R with the Liner Dropped works well . Mine had 1/4 Turn ( on a MVVS needle ) richer ' cowl closed .
A close fitting to cylinder team race like set up . thinking ' The Wind ' pressureised it , in a howling gale .
So the Power Came UP to hold a even speed .
Or it was my magical muffler . 

The Speed 60 Webras ( ( The Timing varies with series ) might work , if your nose is short .
Theres the old 5.6 MVVS Sirotkin used . And perhaps someones using a OS max 80 . Soon as the Cowl Magnet & Mufflers figured . 

[M Spencer]

Igor Burger
Re: Josef Gabris "Super Master"

MVVS is not soviet engine it was produced in Czech town Brno on regular basis ... factory called MVVS ... it still exists and still makes engines, nowadays also electric.

MVVS 5.6A was made 1957 in first run really only 20 engines and given for testing to stunt guys, but later produced regularly almost everyone who flew stunt had it here. That engine on picture is from regular production, becuase that first run did not have screw for muffler. That motor was designed especially for C/L stund and those days mufflers were not necessary. Later they made exhaust screw either for muffler or for exhaust valve for R/C version.

MVVS 5.6A was dedicated for stunt. However the MVVS 5.6A was BACKWARD modified to speed 5ccm version and it was used by Bohumil Studeny for making speed record 244km/h and then the MVVS did a clone of that motor for speed. That modified engine from regular production was called MVVS 5R.

Before those 2 motors we had also speed engine 5ccm produced in Prague, called "Vltavan 5", it was designed and developed in MVVS, but for another factory.

[Lauri Malila]

.

[Massimo Rimoldi]

Massimo …. Looks like a shorter shaft version of the ones Randy has shown … Do you know in what configuration he (Yuri) ran the motors …. Which way was the cylinder pointing, …. Down, outboard, or inboard?

Hi Frank,
as Lauri has already said this is not a different version of Belko's engine but the version of the first DR (9 cc I believe)
Unfortunately I have never seen this engine, I have only captured this picture somewhere on the web.
If you are looking for engines with R.I. I can give you these photos, these are two different SKIF 9.5cc that Dave talks about.
The recent version .76 is F.I.

Regards, Massimo

[Dallas Hanna]

This was the RIRE MVVS stunt engine of .49 or .51ci size from the 1990s Frank.  Really not sure if 49 or 51 as it could have been just marketing.  The first ones I had was .51 on the box and last few was  .49.

HH

[Juan Valentin]

           I acquired a while back this pair of MVVS 5.6  I think they are similar to the ones used by Josef Gabris in his Supermaster. I have never seen this engines with the mufflers installed on a Stunter.
                                                                                                                                       Juan

[Randy Cuberly]

Frank,

Regarding your comment to Massimo, it's not a shorter version. Different constructor, long shaft engines are from S. Belko, DR from Yuriy yatsenko.
Rear intake has many benefits, I like it. Here is some pictures of my junk.

Lauri

Lauri,
You probably get tired of hearing the praise of your remarkable skill and craftsmanship but I will add some to it.
That is truly magnificent, skillful, machining and design.
Thanks for showing it!

Randy Cuberly

[Lauri Malila]

Thank you, Randy.

But with this one it went wrong, when it comes to user-friendliness: It’s nice to have remote valve close to venturi, and it’s nice to be able to remove the engine without screwing up the needle setting.
It’s also great to be able to change venturi without removing the engine from model.
But it’s not nice at all that when in need to move tank, both engine AND valve need to be removed. L

[frank williams]

Lauri, Lauri, Lauri ...
I've heard about your motors but have never seen pictures of one.  Magnificent craftsmanship.  I agree with Randy, they are great and very inventive.  Thanks so much for your pictures and contribution to the thread.  Wow a truely beautiful motor.

Juan
Wasn't the Chech flyer who won the worlds back in the 60 (can't for the life of me think of his name) using rear intake MVVS motors.  I think they were copies of the Dooling 29 but done in a 35 displacement.

Dallas
I just got out my MVVS 4.9 (5.1) rear intake and just noticed that the cylinder could be rotated 180 degrees.  I hadn't noticed that when I ran it for the time that I did.

Massimo, Dave
The Skif 9.5 is a very ice looking engine, great castings.

My thoughts on stunt motors keep coming back to, 1) you have to keep the glow plug lit and 2) you need an engine that is a good pump to draw the fuel to the engine under maneuver load.  The inboard cylinder addresses 1) and the rear intake addresses 2) in several ways.

One more thought .... with rear intake its easy to turn the motor into a pusher.  The idea of pushers isn't as big of a problem now that there are many props available for that direction of rotation..

[Brian Hampton]

I acquired a while back this pair of MVVS 5.6

An engine test for you. http://sceptreflight.com/Model%20Engine%20Tests/MVVS%205.6.html

[Juan Valentin]

 Hello Brian
                         I saved the engine review in my PC . Josef Gabris was European Champion in 1958 and World Champion in 1966 and 1968 with the Supermaster.
                                                                                                                                                                                  Juan

[frank williams]

Thanks  Brian for the article.
My apologies to Juan ..... you said it was Josef Gabris who used them and I completely overlooked it.  Don Still had one in the counter at his hobby shop that he had traded a Fox35 for at one of the WC's.  It looks like it was a twin ring motor with a "plastic" disk.  A little heavier than a Fox 35, but most likely a superior engine.

[M Spencer]

 Lauri Malila

Rear intake has many benefits, I like it. [/quote]

Would you ,make a list ! . 

Can you get your finger in to choke / draw the fuel ? or just hold nose down to prime / nose up to prevent flooding / draining the tank .
Thinking of ' slip on ' cowl , with magnets . So can be slipped on  after start up
 ( A few of mine are mounted inverted from top side , so cowls a lower engine cover )

The creators of SKIF - Vladimir Strakhov and Mikhail Makarov

From Elsewhere .

SKIF 9.5

[Lauri Malila]

[quote,make a list ! . 

Can you get your finger in to choke?
[/quote]

Matt,

Priming is not an issue, quick & clean with a small syringe + a long needle.

Benefits of rear indiction, not in any particular order:

-It's possible to make a lighter and stiffer engine, front intake construction is structurally kind of a monster.
-I have my doubts if one should aim for smallest possible bottom end volume in a stunt engine, but rear intake is better for that. It's also possible to have much more clean gas flow from venturi to scavenging. To avoid fuel/oil accumulation in weird places, one shoul eliminate as much discontinuations in flow as possible.
-It's possible to use a remote needle valve but still keep it very close to venturi. I like the idea from isolating the valve from engine heat. And actually isolating the whole venturi assy from heat.
-And of course, with rear intake it's more easy to do experiments with intake timing & duration.
-The airstream going into venturi is more predictable as it's not disturbed by the mess of air near propeller center.
-Also, the engine sucks air from a kind of a plenum chamber that is heated by engine. This makes kind of a self-regulating system; warmer air > richer air/fuel mix. At least in theory

L

[Juan Valentin]

Hello Lauri
                       Can you post some pictures of the whole airplane you have the rear intake engine in? Thanks.
                                                                                                                                                                                 Juan

[Lauri Malila]

Here is some, Juan. L

[Juan Valentin]

 Hello Lauri
                          Thanks. beautiful airplanes.
                                                                                       Juan

[M Spencer]

Thanks Lauri .

The Hot Air / Vaporiseation thing is intresting . Smoother Running .
We are not after top end power / cold air / charge density etc .

Have Four RPR HP 40s now , as was impressed by run on my 130/110 timed one, V Load responsive . Even Airspeed .

Just Tripped over this : as ' we ' are wandering  . 


We're All right for RINGS , Then .

MVVS 5.6 . obviously .

[Igor Burger]

This was the RIRE MVVS stunt engine of .49 or .51ci size from the 1990s Frank.  Really not sure if 49 or 51 as it could have been just marketing.  The first ones I had was .51 on the box and last few was  .49.

HH

It is MVVS GRRT. It was orriginally designed for pylon race. Later made with slow timing for stunt. Volumes were:

6,5 ccm (.40)  - head did not have round cooling fins and sometimes removable front of crank case with bearing on 4 screws 
7.2ccm (.44)  - had larger bore and the same crank, but larger bore needed new head that had round fins like on your picture
8ccm (.49) - had larger bore and also larger crank, and that was reason for different bottom of motor, visible on my picture

So I GUESS that your engine is .44 as it has smaller case, however they did not make them searial, at least not in large series, so they were more like prototypes, therefore I only GUESS. My picture shows 8ccm .49 engine how I flew them and also model Shark of Ivan Cani designed specifically for MVVS GRRT.

[frank williams]

Thanks Igor
The one I have must be the 7.2cc.  I had to look for a while to see the difference of the 8.0cc.  I haven't flown mine recently, but it did run well.  Also a well made motor.
Frank