How powerful was an Ohlsson '60?

An L&J Fox.35 or a Brodak .40 will outperform it. I have an O&R .60 I used on a Playboy Sr. No hot rock there. A Johnson .35 did a better job.

One of the gentlemen who flew Ignition at the VSC flew a Jamison Special with a side port Ohlsson .60 (converted to a front rotor)
The airplane flew well with plenty of power.

A ST .46 would work well, or your Enya .49.

De,

That's an interesting observation. I have a front rotor converted sideport that is hotter then either of the original front rotor .60's
I have. I've flew OT free flight with it and it will pull an 8 footer right along side a Super Cyke. Don't know why, but its true.

An L&J Fox .35? Wow, that's surprising.

I've got a couple of those, actually.

If I build this thing light, it might work, as there is only 35 inches of wingspan. Don't know the wing area. I thought something in the .46 range would be good, particularly to swing enough prop to get some disk out past that fat cowl.

But mayb an L&J with an 11/4 or 10.5/4 would put this tractor in low gear all the way round the circle and up over the top.

Does anyone know of anyone who built this design?

Cy.

How about comparing it to the 38 Special? My recollection of the Model Aviation article by Tom Dixon is that he thought the stock(?) Fox .35 was short on power and used a reworked Royal .40 as shown in the pictures. In comparison, your DR.I seems like it would have less drag from the wings (span and thickness) and more from the fuselage. As to the power from an O&R .60 ---I only wish I had one to compare! Currently I am looking for the ignition parts to "re-convert" an Atwood .60 with the rear venturi. It seems like it is in good shape and it would be fun to try it. I suspect it has more umph than the O&R...? Any help from the guru's?

The name I seem to associate with CL stunt biplanes is Claus Maikis(? sp). You might try a seach thru the MA archives.

I ordered plans a while back from Dixon for his semi-scale Pitts. Not sure if I will build that, or just use it as a guide to design a Starduster II. I have the plans for that full size bird. Love that biplane shape!

It may not have been a Ohlsson 60 ignition, I can remember seeing Ohlsson 60 glows in my LHS in Argentine, Ks. If I remember correctly the head on them was purple!!The Glow version was probably more powerful than the ignition one.

by the way, those purple heads are running around $400 bucks right now!

I've got a .38 Special kitted by Dixon. I built and used an ST 'V' .51 bb on it with triple head shims. High altitude here, and I wanted the extra poop, but not that much more than the .46. A finer engine/plane match you cannot find.

>How about comparing it to the 38 Special? My recollection of
>the Model Aviation article by Tom Dixon is that he thought
>the stock(?) Fox .35 was short on power and used a reworked
>Royal .40 as shown in the pictures. In comparison, your DR.I
>seems like it would have less drag from the wings (span and
>thickness) and more from the fuselage. As to the power from
>an O&R .60 ---I only wish I had one to compare! Currently I
>am looking for the ignition parts to "re-convert" an Atwood
>.60 with the rear venturi. It seems like it is in good shape
>and it would be fun to try it. I suspect it has more umph
>than the O&R...? Any help from the guru's?
>
>The name I seem to associate with CL stunt biplanes is Claus
>Maikis(? sp). You might try a seach thru the MA archives.
>
>I ordered plans a while back from Dixon for his semi-scale
>Pitts. Not sure if I will build that, or just use it as a
>guide to design a Starduster II. I have the plans for that
>full size bird. Love that biplane shape!
>
>Dave
>LA_Flyer

Talk to Charlie Bruce on the Atwood, George Aldrich told me he was THE Atwood man on the planet, and having known CB back some 35 years ago I can attest that is so.

Jake

>An L&J Fox.35 or a Brodak .40 will outperform it. I have an O&R .60 I used on a Playboy
>Sr. No hot rock there. A Johnson .35 did a better job.

All of the Ohlsson engines were way down on power compared to almost any other brand from the same period. The 23's amounted to the most overweight of Half-A powered toys. The O&R 29's weren't quite as puny, maybe as strong as a GH 15, but probably not quite. I'd say that one of their 60's had equivalent power to an average 29 from 1950 or so, when run on glow fuel. I never tried an O&R Sparky, but I'd have to guess that they were somewhat worse on gasoline than on methanol.

.

Kiwi

LAST EDITED ON Apr-15-04 AT 04:30 PM (CDT)
 
Ron B.
F4Fguy

The direct answer to your question is:1/4 HP @7500 RPM.

This is considerably less than almost any modern .35 or .40,but,as usual,doesn't tell the whole story.These things had TORQUE!They were commonly run with props up to 14-6's.In what was laughingly referred to as "speed" in those days,a common setup was a 10-10 or 10-11.I don't know of any stock modern engine which is directly comparable.

Your fears of too small a prop arc aren't necessarily warranted as long as there's good flow space behind the prop arc,but it sure will look strange.What is really needed is a 2:1 geared .40FP to swing a realistic prop size.If you decide to build this as an old time model I'd use the Ohlsson.They're readily available as "runners",and are nice handling engines as sparkers go.

Ron B.

Edit:Sorry,I didn't catch the date first time,I guess old time is out.

"Back in the day" (mid fifties) my brother and I put together a twin boom stunter using an extended "Chief" wing and a bunch of custom built addons(booms,rudder,flaps, elev, etc.) We had this good running Mac 49 to power it. Took it out to the field and YUK! What a piece of $%#@. Way to heavy!!Dissapointed we brought it back home, My brother gave up on it. I suggested the O & R 60 and he just laughed. "If the Mac won't do it, the O & R aint got a chance" Well I'm here to tell you that O & R 60 made the best dang stunter that we had to fly for at least three years. Plenty of power, excellent 2-4 break. No one ever believed it was a bone stock engine, but it was.

I would imagine a late model .46 or .51 would do the same job today without any trouble, but fifty years ago that was a real treat!

> short nose moment to reduce gyroscopic
>and pitching effects.

The length of the nose has no effect on the gyroscopic effects. Torque is torque, no matter where you apply it.

>> short nose moment to reduce gyroscopic
>>and pitching effects.
>
> The length of the nose has no effect on the gyroscopic
>effects. Torque is torque, no matter where you apply it.
>

As I understand it when you have a spinning disk and input a force (i.e. change pitch) the gyroscopic precession translates the force 90 degrees (in our case into yaw). That is what Al Rabe designed his rudder to counter-act.

I'm surmising that the longer the moment from the CG to the plane of the prop, the larger the effect--all other things being equal. Which they of course never are. Doesn't the yaw force get more leverage if the nose is longer and less if it's shorter?

And does anyone have a weight on an Ohlsson 60 glow so I could figure the difference?

Thanks all for the discussion thus far.

Cy.

>>> short nose moment to reduce gyroscopic
>>>and pitching effects.
>>
>> The length of the nose has no effect on the gyroscopic
>>effects. Torque is torque, no matter where you apply it.
>>
>
>As I understand it when you have a spinning disk and input a
>force (i.e. change pitch)

rate, not force

> the gyroscopic precession
>translates the force 90 degrees (in our case into yaw).
>That is what Al Rabe designed his rudder to counter-act.

Torque, not force. In fact, Torque = omega x L, where omega= pitch rate, and L = angular momentum of prop, and x is the cross product operator.

>
>I'm surmising that the longer the moment from the CG to the
>plane of the prop, the larger the effect--all other things
>being equal. Which they of course never are. Doesn't the
>yaw force get more leverage if the nose is longer and less
>if it's shorter?

It's not a force, it's a torque, so the position at which it is applied doesn't matter.

>>As I understand it when you have a spinning disk and input a
>>force (i.e. change pitch)
>
> rate, not force
> Torque, not force. In fact, Torque = omega x L, where
>omega= pitch rate, and L = angular momentum of prop, and x
>is the cross product operator.
>
>
>>
>>IDoesn't the
>>yaw force get more leverage if the nose is longer and less
>>if it's shorter?
>
> It's not a force, it's a torque, so the position at which
>it is applied doesn't matter.
>
> Brett

Well, wow.

That is a great bit of information.

Amazing I got this far with a simplistic comprehension.

What a wonderful community. Between the wealth of lore on the Ohlsson and the physics lesson, the scope of information here for the asking is just great.

Thanks, Brett.

And everyone else.

Cy

>> short nose moment to reduce gyroscopic
>>and pitching effects.
>
> The length of the nose has no effect on the gyroscopic effects.

I get that torque is a rate.

The other benefit I would see for a short nose would be that when you go to start and stop the pitch, the inertia would be less with the mass of the engine closer to the CG. I suppose that's some what mitigated by the fact that with a shorter nose you need a heavier engine to balance the airplane, but still--when an ice skater pulls her arms in the spin rate increases. When the engine is closer to the CG, isn't that a good thing for making clean hard corners without bobbles--all other things being equal?

Which they never are.

Cy.

LAST EDITED ON Apr-16-04 AT 11:28 AM (CDT)
 
>>> short nose moment to reduce gyroscopic
>>>and pitching effects.
>>
>> The length of the nose has no effect on the gyroscopic effects.
>
>I get that torque is a rate.

Torque is the result of changing the direction of the angular momentum vector (L) of the prop (and spinning parts of the engine). Since this is fixed to the body, the rate of the body *creates* the delta-L and thus the torque.

Also, you might consider that the rate is actually in two directions even in level flight. You are yawing around relative to inertial space, too, since you are going in a circle. You might think this is too slow to be considered, but at 5 seconds a lap, that's fully 1/5th of the pitch rate in a hard corner. The direction of the resulting torque is to pitch the nose "up" in the frame of the airplane.

And hey, how about that, if you put in some positive incidence in the tail, it's in the direction to counteract this torque. What a puzzling coincidence...

I might note that airplanes like the DR-1 that used the "rotary" engines, where the crankshaft was fixed to the airplane, and the entire engine rotated around it, were notoriously hard to handle. The engine/prop was hugely heavy and had a massive amount of angular momentum - so every time it pitched it also skewed off to the side. In fact, this, and many other propellor-driven fighters, could only pull out of dives in one direction - because pitching up forced them to yaw in that direction and they couldn't force it back the other direction. So the attacking pilot would get them to dive, and then hang off to the side, wait for them to pull out in the predicted direction, and then get a nice clean shot at them.

>
>The other benefit I would see for a short nose would be that
>when you go to start and stop the pitch, the inertia would
>be less with the mass of the engine closer to the CG. I
>suppose that's some what mitigated by the fact that with a
>shorter nose you need a heavier engine to balance the
>airplane, but still--when an ice skater pulls her arms in
>the spin rate increases. When the engine is closer to the
>CG, isn't that a good thing for making clean hard corners
>without bobbles--all other things being equal?

Sort of. You are referring to the pitch moment of inertia. The moment of inertia contribution of a particular mass is proportional to the mass and proportional to the square of the distance (from the CG in this case). So for a given airplane, a heavier engine shoved closer to the wing, to get the same CG, does have less moment of inertia and thus takes less pitch torque to accelerate or decellerate in pitch.

I would also note that in Ted's late-70's experiments, he noted *no* effect of changing the nose moment as long as you kept the CG in the same place. That's a little counter-intuitive to me, but it may be that over the short range of the test, it was too small an effect to be notices. The nose is already ~1/2 or less of the tail (measured from the CG) which means an ounce on the tail contributes 4x+ the moment of inertia of an ounce on the nose, so changing the engine and leaving everything else alone doesn't change the entire inertia all that much.

I'll have to go re-read Gialdini's article to see if this is really the same as his description of the "barbell" effect. It's not the same as the "barbell effect" that Leonard describes on the main site here - and I might add I don't agree with the analysis associated with it, either. More diameter is not really "compensated for" by moving the CG back to more than first approximation.

Whether that makes it "bobble" less, or more, depends on a lot of other factors. If it worked fine with a light engine far from the CG, it's not likely to work the same with a heavy engine close to the CG. The reduced inertia may help or hurt, and the extra weight (by virtue of the heavier engine) may help or hurt, depending on many other factors like the airfoil, effects of the flap. and on an on. In general, takingn a good system an simply perturbing it by reducing the pitch moment of inertia and increasing the wing loading may make it pitch faster but require more AoA to change directions - setting up a classic 'hop" out of each corner. On the other hand it may be over-flapped to begin with and this will help. You just don't know.

A lower pitch moment of inertia would generally be better, but in this case you are giving up something (weight) to get something else ( moment of inertia), and it's not at all clear whether it's better, worse, or just different without doing the analysis for a particular case.

I'll have to go read Gialdini's article to see if this is really the same as his description of the "barbell" effect. It's not the same as the "barbell effect" that Leonard describes on the main site here - and I might add I don't agree with the analysis associated with it, either. More diameter is not really "compensated for" by moving the CG back to more than first approximation.

I think you're biggest concern would be engine weight. The DR-1 has such a short scale nose. Modern engines that will turn a 12in. prop are probably lighter than the O&R and will need a longer nose.

A friend, Pete Simonson, built a very stuntable Triplane back in the 70's. He used a Fox 35 and extended the nose about 1.5 in. from scale to get proper balance. It had about 30 in. span I believe and was true scale outline, except for the nose.

Interesting comparison. I just weighed an O&R .60 and a Stalker .60

O&R 11.4 oz with timer
Stalker 14.7 oz with short muffler

>Interesting comparison. I just weighed an O&R .60 and a Stalker .60

Thanks, Randy!

Adding to that, here are some weights of possible engines:

Stalker .60	14.7 oz with short muffler
T&L ST .60 (2)	12.4 and 12.00 oz
VECO .45	11.49 oz
Ohlsson .60	11.4 oz with timer
OS Max .49	9.9 oz
T&L ST .46	8.05 oz
Brodak .40	7.67 oz

I weighed some candidates from my engine stash and discovered that the VECO .45 weighs close to the original Ohlsson. I had expected the OS Max .49 to be the likely engine for this, but the VECO looks like the better match to the design. It anything, it's a bit heavier, which will counter any tendency I have to make the tail heavy by building with lots of glue.

This is cool, as I've been wondering what I could use the VECO for. I remember it being heavy for the displacement. Put a low pitch prop, say, a 12/4, on it to get as much prop disk as I can and things should work out well. A .45 seems like plenty of engine for this design. It's only got a 35 inch wingspan. But with lots of power going into a big prop at lower pitch and all that drag and lift from all those wings, it could turn out to be a fairly steady tractor around the pattern. (Not that I can fly the whole pattern.)

One now wonders if a Rabe Rudder would be a good addition. The Triplane has a small, all flying rudder instead of a fin and rudder.

Cy.

>I've just scored a set of plans for a Fokker Dr.1 Triplane
>from 1954 with a fully symmetrical airfoil. I've always
>thought the Dr.1 would make the basis of a good sport stunt
>ship, lots of lift, short nose moment to reduce gyroscopic
>and pitching effects. Big elevator way back for control
>authority. This is not a scale plan, but it's pretty close.
> The airfoil has the mid point a bit farther aft than I
>might expect, but it's dead symmetrical as is all of the
>other setup. So it should stunt reasonably well if built
>light and enough power offsets the drag.
>
>The plans call for an Ohlsson '60, which is radially mounted
>right to the firewall.
>
>[photo not recovered: 407dfebd487a08bf.jpg]
>
>I have no idea what the relationship is between old engines
>of that era and more modern types. I've got a ST.60 I could
>put in this thing, but it's not THAT big. I'm wondering if
>a ST.46 might do a good job. Or an Enya .49.
>
>Can any of the old timers give me a sense of what kind of
>engine the Ohlsson 60 was back in its day and what a
>somewhat more modern equivelant might be?
>
>I don't want to invest in a brand new AAA whizbang motor,
>but do want to plan to put something from my modest
>collection of semi-classic stunt engines in this thing.
>
>And any suggestions for a great paint scheme would be
>enjoyed as well. I'm not about to just paint the whole
>plane red. Too easy.
>
>Thanks in advance.
>
>Cy.

Thats an old Air Trails plan and the motor is an O&R 60 FV GLO My brother built that plane,I still have the plans, it needed nose weight. The O&R motors were not that successful as a glow. Remember it was still basically a sparker converted and timing was so tame in it that it was one of the reasons that it lived as a glow. Harry Rice was reluctant to really revamp the line. My understanding is that is what ultimately did O&R in, their inability to adapt to the rapidly changing market at that time.
At any rate my brother did use an O%R 60 and the line length was 52 feet, a powerhouse it wasn't Dennis

They can run ok, but don't push 'em too hard- the head is a "shrink fit" to the cylinder and it can be blown if the motor gets too hot. Needs ALL castor oil fuel (keep the oil content on the high end) and the right prop and it will do allright.

Jake

>And any suggestions for a great paint scheme would be
>enjoyed as well. I'm not about to just paint the whole
>plane red. Too easy.
>
>Thanks in advance.
>
>Cy.

There are several Dr-1 paint schemes which are eye-catching. Some are pictured in the Squadron Signal Publications book: "Flying Colors".
There is also a Profile Publications issue on the Dr-1 (hard to find now).
There was an overall black triplane, also a rather pretty one which was overall medium blue with the rear fuselage section and tailplane in white. Standard finish for the Dr-1 from the factory was the clear doped olive green dyed fabric on all surfaces and dark green paint on the metal cowling.

Jake

LAST EDITED ON Apr-15-04 AT 07:01 PM (CDT)
 
Gotta' clear up a few things about the O&Rs

"the head is a "shrink fit" to the cylinder" This isn't so, all Ohlssons had integral steel cylinder/heads. They were fitted into the case and 2 steel slugs were resistance welded onto the cylinders through receiving holes in the case. They then pressed aluminum plugs over them to seal the cases. The later Ohlssons had aluminum finned head heat sink staked onto the integral cylinder/head giving the appearance af an aluminum head with no fasteners. High nitro has been know to break the cases out at the steel slugs but I assure you never was there a head blown off and Ohlsson.

"Needs ALL castor oil fuel" If your running it glow I agree, however these engines were designed to run on a premix using heavy straight weight oil, I use 70 weight. White gas is OK and the engine will run a it cooler. I know of guys that have used castor in their premix but the castor goo dosen't help the plugs much.

Probably the biggest problem you'll have now with an original is that after all these years it that the cylinder base gaskets will most likely leak and they cannot be changed without all the proper equipment, none of which you will have in your shop. There is a gent,(name slips my mind) that does this as a service, its a very involved process.

Kiwi, while I respect your input always I have to disagree strongly with your statements on the power outputs of these engines. I have flown a 4 lb OT free flight with an O&R .60 and it will climb at better then a 45 degree angle, my Fox 29XBB wouldn't come close to that on the same model at the same weight. Granted, that's an old glow engine, but anyone that's ever used one can attest to its performance, really awsome on a large B class FF.

I will agree that some of the last of the breed were sickos. They used a fairly ingenius deep drawn stamped steel piston, but as the tool wore the crown radius got ever larger. As that happened the timing was advanced and the actual compressed volume was smaller and the CR reduced, power degraded as production went on. In their day however, they were fairly formidable engines. They were used widely. It is true that they were less expensive, but that was because of advanced production techniques, not lack of quality. A good Ohlsson was a fine dependable engine.

First shot is a late front rotory with a staked on finned aluminum heat sink.

Second shot is an original side port.

Third shot is a converted sideport, O&R marketed kits to do this as well as inverted conversions.

In answer to the original question, it was fairly normal to overpower early CL models in the pre Fox .35 days, particularly ignition models. I think either your ST .46 or Enya .49 would be good choices. Remember that while this model may not be all that big, three wings and that large frontal fuse area will be allot of drag.

Thanks for the correction. I had three of them and had been told that the head was separate from the cylinder. I knew about the spot weld problem though. I still think they were very fine engines; the .29 and the two .33 FRVs had some of the finest fits and such I have ever seen. The .29 would start first or second flip every time, and it ran VERY well about like a Fox .29 Stunt- never ran the .33s tho.

Jake

LAST EDITED ON Apr-15-04 AT 08:36 PM (CDT)
 
I owned at least one each of the 23, 29, and 60's made by O&R in the early 1950's. The 60 didn't stay around long. The cylinder popped off while running rather ordinary fuel at a rather low rpm on a big prop as suggested for the engine. It didn't do at all well on the front of a Stuntwagon when it did run. The same Stuntwagon flew quite well with a Torp 29 later on.

The 23's came apart in relatively minor crashes into comparatively soft grassy dirt (in Texas, we do have a lot of clay that can dry as hard as concrete. The field these 23's broke up in had been used in agriculture and was still porus and soft). Neither of those were capable of powering a Ringmaster Jr. sized model on 52' 015's at a speed that generated any decent line tension (a scratch built whatever that was somewhat related to a Flying Clown).

One of the 29's was better than the other, and handled a plane that was based on a Super Clown relatively well, although slowly with the recommended prop. I consider the engine design(can't believe the goofy typo I made first there) excessively fragile, massively underpowered for their displacement, and hugely low in compression (new 23's felt softer on that than a worn out Fox 35).

I was sub-14 years old when I got those O&R's, and didn't expect much, but they were affordable at a point when the new cost of my (woulda- been preferred) K&B's came to about two weeks' worth of newspaper deliveries on a 40-paper route.

.

Kiwi

I have one of the sideport 60's in a Play Boy with an 80" wing,and as Randy says it hauls it great. Mine is about a 1946 model with the small port and I had the case gasket replaced by George Talent in AZ. He also balanced the crank and tightened the intake tube. I run this motor on spark and 5% nitro glow fuel and it will turn a 13x4 APC prop at 9100 rpm. Starts first flip almost every time. Super compression. I really like this motor as it handles very well and runs very steady. Not as loud as my Super Cykes and Atwoods.

Jim,

You bring up an intersting point, that being the noise level of these engines. They were really very quiet compared ot others like the Cykes, Atwoods, Contestors, Ardens and Rockets to name a few.

My Dad flew early RC and in the late 50's powered a 6' Paramount Commander fully laden with its dinosaur radio gear and doorbell batteries with a front rotary O&R.23. Most remarkable and always requested was to see it ROG. On release the tail was up instantly and T.O. roll of no more then 20'. That's alot of oumph from such a little motor, and much quieter then the Torps that were gaining popularity at the time.

LAST EDITED ON Apr-15-04 AT 08:28 PM (CDT)
 
Kiwi,

You were into the last production runs of O&R, the dregs unfortunately. There are still many of earlier vintage in use in OT FF and doing well. Of course in FF the engine runs are so short the cylinder base gasket leakage isn't so much of a problem because they normally don't start to leak until the cases get good and warm. These engines were quite fragile but that was because the die castings were so finely made to thin wall sections to save on weight. Close examination, considering the vintage of the Ohlssons, will reveal cutting edge technology compared to most of their contemperaries.

I have heard of guys using Coleman fuel with good results, but I've not tried it myself, I still like the stench (make that aroma) of gas & oil.

LAST EDITED ON Apr-15-04 AT 07:54 PM (CDT)
 
Gee Randy: that was a great history and lesson! I have three brand new Ohlssons that I was going to run someday. My favorite is the .33 FRV Redhead glow. Also a .23 ignition and a .29. I'm into freeflight as well, and will use the redhead for sure. White gas, Coleman camp fuel work? Thanks, William Henri (always learning)

>Gee Randy: that was a great history and lesson! I have
>three brand new Ohlssons that I was going to run someday.
>My favorite is the .33 FRV Redhead glow. Also a .23
>ignition and a .29. I'm into freeflight as well, and will
>use the redhead for sure. White gas, Coleman camp fuel
>work? Thanks, William Henri (always learning)

Ron B.
F4Fguy

William:
I think you'll find the Coleman/oil mix unsatisfactory on glow.It works great on spark though.Otherwise,everything Randy said.

Yes, I assumed you were talking spark ignition for Coleman fuel.

Yes, spark ignition for the Coleman fuel. Thanks.

>Gotta' clear up a few things about the O&Rs
>
>"the head is a "shrink fit" to the cylinder" This isn't so,
>all Ohlssons had integral steel cylinder/heads. They were
>fitted into the case and 2 steel slugs were resistance
>welded onto the cylinders through receiving holes in the
>case. They then pressed aluminum plugs over them to seal the
>cases. The later Ohlssons had aluminum finned head heat sink
>staked onto the integral cylinder/head giving the appearance
>af an aluminum head with no fasteners. High nitro has been
>know to break the cases out at the steel slugs but I assure
>you never was there a head blown off and Ohlsson.
>
>"Needs ALL castor oil fuel" If your running it glow I agree,
>however these engines were designed to run on a premix using
>heavy straight weight oil, I use 70 weight. White gas is OK
>and the engine will run a it cooler. I know of guys that
>have used castor in their premix but the castor goo dosen't
>help the plugs much.
>
>Probably the biggest problem you'll have now with an
>original is that after all these years it that the cylinder
>base gaskets will most likely leak and they cannot be
>changed without all the proper equipment, none of which you
>will have in your shop. There is a gent,(name slips my mind)
>that does this as a service, its a very involved process.
>
>Kiwi, while I respect your input always I have to disagree
>strongly with your statements on the power outputs of these
>engines. I have flown a 4 lb OT free flight with an O&R .60
>and it will climb at better then a 45 degree angle, my Fox
>29XBB wouldn't come close to that on the same model at the
>same weight. Granted, that's an old glow engine, but anyone
>that's ever used one can attest to its performance, really
>awsome on a large B class FF.
>
>I will agree that some of the last of the breed were sickos.
>They used a fairly ingenius deep drawn stamped steel piston,
>but as the tool wore the crown radius got ever larger. As
>that happened the timing was advanced and the actual
>compressed volume was smaller and the CR reduced, power
>degraded as production went on. In their day however, they
>were fairly formidable engines. They were used widely. It is
>true that they were less expensive, but that was because of
>advanced production techniques, not lack of quality. A good
>Ohlsson was a fine dependable engine.
>
>First shot is a late front rotory with a staked on finned
>aluminum heat sink.
>
>Second shot is an original side port.
>
>Third shot is a converted sideport, O&R marketed kits to do
>this as well as inverted conversions.
>
>In answer to the original question, it was fairly normal to
>overpower early CL models in the pre Fox .35 days,
>particularly ignition models. I think either your ST .46 or
>Enya .49 would be good choices. Remember that while this
>model may not be all that big, three wings and that large
>frontal fuse area will be allot of drag.
>
>
>Randy Ryan
>AMA 8500
>SAM 36
>I fly 'em all and love it!

Ron B.
F4Fguy

What he said!!!

If you want comparable weight and torque for a larger prop with an available engine, you might consider a diesel such as the PAW40. As a bonus, the smell is vintage, too.

Cy,

Is this an old Flying Models plan? I see by the engine drawing it used the glow model O&R. I'm interested in this plan, can I get a copy?

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Randy, I mentioned that I have that plan somewhere in the house. Haven't seen it in over 30 years but it's here. It is fragile and the creases are worn but if and when I find it, it's yours. Dennis

Thanks Dennis,

Somehow I missed that in your post, guess I was wrapped up in the engine discussion.

>Cy,
>
>I'm interested in this
>plan, can I get a copy?
>
>Randy Ryan

I got mine from Bill Miller who sells rebuilt plans on eb*y.

They came new and fresh, rolled in a tube for $9 plus shipping.

Selling plans on ebay is a marginal activity fraught with cheese artists willing to draw a fewl lines on paper and make a lot of puffy claims. Buying them there is prolly not the cleverest use of one's time and money.

But I'll have to say that I'm pleased to have a really good set of plans for a model I've been looking for at a reasonable price---given what has been done digitally to restore them.

I suggest you give him an email and ask about a copy.

Cy

Yeah, Amen to that!! I bought off E-Bay a set of plans for a B-36 and another set for a B-29 from the same seller. He advertised them as being great scale drawings with LOTS of detail---- They were poor reproductions of some old Eureka kits and unreadable hen-scratchings as instructions. Scale is not consistant fron one view to another. Watch out for scale plans and ASK a LOT of questions before you bid.

Bigiron

You have to be real careful about some plans no matter what the source. I have seen gross errors on some that you couldn't possibly build the airplane the way it is shown in some parts. A prime example is the old Berkeley kit of the Mark 30 Zilch. Don MacGovern did the design, however whomever the draftsman was that actually drew the finalized kit plans didn't realize that the motor shown will never work. The plans show a Fox .09 sideport; however if you measure both the kit and plans using an actual engine (I did), it won't fit because the fuselage is too narrow. The engine mount beams actually wind up sticking out 1/8" outboard of the outer fuselage sides. Can't be done. Also, none of the kit parts match the plans exactly (some aren't even close) as to size or shape. Hands down worst kit I hever had, other than a Comet Rookie Trainer.

Jake

This year at VSC, Greg Allison from Tucson flew a C/L sunter with an O&R 60 FRV on spark ignition. I was amazed at the power of this engine. It seemed to be equal to a Super Cyke. The nice thing about the O&R is that people like Vic Didelot and George Tallent can keep them running with parts and rebuilding service.