A cute little amphibian has chosen me as it's new owner. It's previous owner passed away unfortunately.

It lost a web in it's earlier life, but is otherwise is in very good order. Dr. Owen ran his expert eyes over it and with carful care sorted some minor ailments.

I will run it shortly and will post back. P/L, C/P and bearing fits are excellent. It am hopeful it will not croak.

Small diesels are addictive.

Fiery when does that engine date to ?? martin


CCs??

The Frog 80 Mk1 came out in 1957-nominal capacity 0.8cc. It replaced the none too successful 0.5cc Frog 50 which was dropped from the Frog engine line. The 80 had an o-ring sealed contra-a la McCoy and OK Cub diesels, making the feel a bit odd to Brit and downunder modellers, and it was replaced by a conventional lapped contrapiston in the mk2 version which appeared a few years later (1961?)-the latter version remaining in production into the 1970's (made by DC not IMA by then!) until the Frog range faded away ca 1974 or 75. No significant difference in performance between the two Mks of Frog 80.

ChrisM
'ffkiwi'

Educated guess - 1958/9 - there is no serial number.

** EDIT **

Upon re-checking there is a serial number. The serial number is lightly hand scribed on the case under the L/H lug. It is 8471.

Derek,

I loved that engine back in the 60's. I Had a MK2 and had it on a Charles Mackey designed Red wing. It was a C/L delta wing with the engine put out off centre on the outboard wing. I used that engine because it was the engine used on the designers model and I had it. It wasn't the most potent engine but it was reliable as I recall. Add to the fact that I always liked FROG engines having a 1.49 vibramatic, the 50, and the Frog 2.49 and 3.5. Alas it is no more it got traded on a model to someone else for something that I can't even remember what.
As to the Red Wing a fellow modeller in OZ was good enough to forward a copy of the plans to me and I cut a kit. Haven't got around to build it yet but it is still on my bucket list to do before I'm history.

Derek,

Here is a picture of Charles Mackey and the RedWing Delta

Ah yes, the Red Wing - an attempt at having living proof that if the thrust line is angled directly at the CG then the out thrust produced yaw has no adverse effects on the models handling.

Hmm, not sure that I buy it but there you have it anyway.

Herewith some Frog sexing information.......[the comp screw on the 80 Mk2 has a non standard tommy bar BTW-not my doing!] The 80 Mk2 uses the same cylinder and porting as the 049 glow-and has one less fin than the 80 Mk1

ChrisM
'ffkiwi'

That's a real work of art.

I love the castings on the F80. I had one many years ago, and just because it was clapped I gave it away. B#gger!

Greg

My thoughts are similar Greg. The quality of casting and materials used do not appear to have been compromised for what was a "budget" priced engine at the time.

Under the R/H lug there is the enscription 'MADE IN ENGLAND'. This is in the finest and smallest raised lettering I have ever seen on a model engine casting. Yet, perfectly readable if your eyes are good.

I am fortunate. The fits of the working parts in the example I have really are exemplary. Despite the ventral web amputation it has only been lightly used to date. I am looking forward to running it. I would like to use my Master Airscrew 7 x 3 propeller, but have misplaced it. A white Keil Kraft nylon 7 x 4 (shown above) will be utilised in it's place. Its small diameter mounting hole has never been drilled out, and is a perfect fit on the shaft.

If anyone has a set of instructions for this wee beast (mine came to my home without a box or manual) I would be most obliged if you could scan an upload them, so I may print a copy.

I ran my wee FROG. It started fairly easily. It liked to be a bit "wet". Choke priming only.

Re-starts, hot or cold, were no issue. Operation temperatures are "cool", even when adjusted for maximum revs, as expected with its finned cylinder.

It turns its propeller steadily. Optimal settings were easily found. The Keil Kraft 7 x 4 nylon propeller was fitted.

Video:

http://www.youtube.com/watch?v=Ahjf0...ature=youtu.be

Would the friend in Australia be named Smith? My neighbor and clubmate is a good friend of Charles Mackey and stays with him on his frequent visits to the US.

Chris, I can't quite see where the Frog thrustline could possible pass through the CG of the Red Wing.

Please explain.

Ray

Hi Ray,
when viewed from above draw the thrust line back through the wing, the original concept was for the thrust line to intersect the CG in order to eliminate the turning effect or yaw that such heavy out thrust would normally give.

Thanks.

P.S. Check the plan, the thrustline goes straight through the bell crank pivot also.

Apart from cutting out different size ribs the Red Wing looks an easy build. How well does it fly?

Chris,

I grasped the concept, and yes it's clear in the plan shown. However I just can't see the thrustline from the Frog in the pic above going anywhere near a reasonably placed CG for a c/l model.

Ray

Ok Ray, Ican supply a far higher resolution plan if need be but .......... on the plan there are two arrows, one directly in front of the front leadout and its matched pair on the opposite wing.

Draw a line between these and that is your centre of gravity pitch axis - according to the plan.

Draw a line down the thrust axis and note the intersection between the two lines.

The intersection is very, very close to the bell crank pivot.

The bell crank pivot is reasonably placed outboard to allow for the required tip wieght and represents the true 3D CG point.

Thats the whole point of the design mate.

( I can come visit Mannering Park around Christmas time to further elaborate!)

P.S. Iagree now, the pic of the model is deceptive indeed but bear in mind that all of these designs were deemed 'experimental' and thus most likely subject to change on a whim.

Indeed!

You are of course welcome at Mannering Park, but only if you bring and fly a diesel or glow powered model.

Either is acceptable.

By the way, a "true 3D CG point" is called the "Centroid of Gravity" as an Aeronautical Engineer friend of mine never tires of telling me.

Sound like something Ken Dowell might have said.

Mmm, I got a Facebook Friend request from Ken a few weeks ago.

Scared the hell outa me!