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General control line discussion => Open Forum => Topic started by: mark gordon on December 16, 2006, 04:08:11 PM
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Hi everyone. I have read this forum for sometime now and have never contributed, so I thought that I would post some photos of my current project. The plane is an australian design called Flapjack. Designed 50/51 by Monty Tyrrell and Kieth Hearn. The engine is a FROG 500 with a muffler I made myself. It currently weigths 26oz and the plan suggests a wiegth of 30 oz, so it will be a tight finish.
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Looks good Mark: Whats the wing span ? and length? I'm not familier with a FROG 500 what size is that ? Would like to see it all finished, so keep the pics coming.
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The Frog 500 is 5cc, or about .29 c.i.d.
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The Frog 500 glow is a 1950 Brit. engine. It was heavily influenced by the contemporary K&B 29. In 1951 an ign. version was produced.
The Frog Co. was a major Brit. Co. that produced kits, accessories, and engines. Their products are now eagerly sought by collectors. Their engine designer at the time was Bert Judge, winner of the 1936 (?) Wakefield comp. The cover of the latest 2006 SAM 35 mag. has a photo of Bert restaging a well known 1936 photo 70 years later, launching a repro of his winning model. Bert designed the Frog 250 diesel, and had a similar 29 glow under design. They tested a K&B 29 and found it 200 rpm faster than Bert's still under-development engine. The directors ordered Bert to use the K&B details!
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Incidentally Ian makes a beautiful reproduction of the FROG 500 glow, he probably makes the ignition too. I had mentioned to him I have one and the serial no is 0002. I hope you kept the first one, Ian.
I got mine from Ed Carlson, probably the first one he got in. This motor was legendary in Britan in the 50's and i had never seen an origional so this was my chance to at least have a great copy of the origional.
One of these days I'm going to bite the bullet and run it, collector value or not.
Dennis
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It is odd to a modern day person (more or less) that the Frog 500 first came out as a glow engine, then a later ignition version.
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Thank you for the vote of confidence Dennis. Remember - traditional running in, like it says in the instructions.
Jim - the ign. was produced to satisfy the r/c boys of the day, who were tuned in to ign. motors.
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There was another FLAPJACK back about that time...
That was the one that had a yoke bridle with a releasable 'catch', that when tripped, allowed the model to do a 180° roll...
Check Tom Morris' OTS or Classic books - it IS there.
PS: I can verify the great quality of Rustler's Frog 500 Glow engines. A friend "acquired" one (thank you, Ian) which we benched a bit. Fabulous! ...and a piece of OT era Brit legend...
We (Jon and I, as well as those of us in Tucson who were able to assist) wish you and your fair lady all the best over the Christmas holiday and into the year 2007.
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The wing span of the FLAPJACK is 38" and it has a fuselage length of 26"
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If I remember correctly from my old FROG engine boxes, FROG is an akronym for "Flies Right Off Ground". Anyone else remember it that way?
George
PS. Nice engine and plane. Good luck with them.
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Hi Mark,
Great looking ship!
For the finish, I would hope you just clear the wings and paint the "wood". That's a design that I think would look very nice with the clear wings.
Save some weight that way! ;D
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I would be very interested in how you constructed the muffler. It looks like a factory accessory- very smooth and nicely detailed. If I built it, it would have a cobbled up look at best.
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Another Flapjack, but a free flight version of the original US Naval Carrier prototype V 173 built by Randall Hopkins of Paducah, KY
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I would be very interested in how you constructed the muffler. It looks like a factory accessory- very smooth and nicely detailed. If I built it, it would have a cobbled up look at best.
Sometime ago I was at an annual event held in Melbourne called the Monty Tyrell Memorial. While attending the event I spoke to a Dave Lacy about the FROG 500 and the fact that it did not have a muffler, he informed me that the OS-702 (strap on early 15 muffler) fitted the FROG and worked quite well. These mufflers are becoming quite rare, so I just made a copy of one instead. The whole thing is made from the aluminium centre tube from a television antenna. After cutting all the pieces I had a local guy TIG weld everything together for me. He found that the aluminium was not of good quality and it was hard to weld together. The main tube of the muffler was just cut to length. The domed end of the muffler was a piece of tube cut along one side and then flattened out, then domed over the head of a bolt and then cut around and filed until it fitted. The tapered outlet was done by taking the main body of the muffler and cutting out four tapered sections and then pushing them together into the middle, then cutting a small piece of aluminium to fit into the centre of the taper. The muffler extention tube was also a piece of tube cut up one side and then flattened out. This piece was then moulded around the exhaust stack of the FROG. I then positioned the extention tube to the body of the main tube marked it and then drilled and filed it to shape. The whole process to me approx 2.5 hrs to do. The actual proof will be in the pudding when I finally try to run the engine.
I hope this helps. I did not think it would be so hard to try and explain here something that I found easier to actually do.
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I'm interested to know how people fix the OS702 silencer to the Frog 500. If the stack is left angled it does fit, but then the silencer is at the same angle, tilted in towards the model and looking most awkward. If you cut the stack square the silencer goes parallel o.k. but then it oversails the stack each end. I get around this by using a thin blanking plate, but I've never heard anyone mention this. Everyone just says "A 702 fits". What does everyone else do?