alpbak

I have an OS 15CVA lying on the work bench. It was on a Herr Little Extra that has met its end due to a bad crystal. I am planning to build a pylon racer for this engine. I am planning to scratch build it from a plan.

I've been looking around for a plan but haven't found what I'm looking for. I found some racer plans for electric and planning to modify them for a glow engine. But if someone knows an original plan for this kind of racer it would be greatly appreciated.

Thanks
Alp

combatpigg

My Feedback: (3)

I would scale down a .40 sized Q500 type plane to about a 36 inch span and 6 inch chord. The Lanier Predator is a cool looking plane. A future project for me. I want to set one up with a 6.5x5 or 6.5x6 prop, cowl the engine and make the plane as light and streamlined as I can. I built a .15 sized racer a couple of years ago with a solid balsa wing, [3/8" thick], with a Super Tigre .15 combat engine. It was never clocked but looked like it was moving pretty good
Some of those electric speed planes look tempting, but I'm not into ARFs.

scudrunner77

CP

Are you planning on racing with SRAC this season? I still have an OS .15 I need to do something with...

combatpigg

My Feedback: (3)

SR77, yes, but if you want to race .15s you have to build a Doubler. Contact SRAC to have plans shipped. The kit is no longer made. It looks more like a flying boat, but they fly nicely.

alpbak

CP
Thanks for the advise. I think I will do what you say. I found a plan on www.pylonworld.com, The Hurikane. It's a Q500 racer, I will scale it down to 36 inches. Hope everything goes well and it flies fast . Any other info or advise is greatly appreciated.

Thanks
Alp

ffkiwi

Do a search on 'Quarter Midget'-[not necessarily just on R/C Universe]the Quarter midget class (now sadly dormant as far as I can gather) started in the mid 70's as a pylon event specifically for .15 size engines-and Rossi's, Taipan Goldheads and Cox Conquests were the engines to have (for the select few, the K&B 15 rear drum). Many of the 'fullsize' pylon 'names' used to fly it as a fun class (just as many F1C fliers today fly F1J as a fun class) Your 15CV will be adequate for one of these-and probably more durable than some of the originals [have you ever tried to buy a 10.5mm bearing for a Mk2 Rossi.........?](thats not a typo by the way-the rear bearing on a Mk2 was 10.5mm ID-only made in one lot by the factory-specifically for Fratelli Rossi)...........yes you can get a replacement-if you're prepared to buy a factory batch of 20,000 minimum!] Be aware though, that a lot of Quarter Midget designs were serious racing machines and used glass fuselages-so reproducing these might be a challenge.
Another option would be to take a Club 20 design-which was a UK development in the same spirit as 'sport 40' pylon-in other words a simple pylon class that didn't require any great outlay and could be flown on readily available sport engines [there were other restrictions such as a minimum specified prop size, no tuned mufflers or minipipes etc] There were many plans for these published in the UK R/C magazines in the 80's in particular. Since the engines used were of the order of the Fox 19, Webra 20 speed etc the CV 15 would be comparable in power.
Again do a google search on 'Club 20' and see what shows up. The advantage of the UK thing is the UK has is a long standing tradition of providing free full size pullout plans in most of its R/C magazines. There is about a 90% certainty that somewhere in the last 25 years or so there will have been several Club 20 designs amongst them. All you need do then is get hold of the magazine or plan (admittedly a wee bit of a challenge if you're in the US, but that's why we have the 'net these days)
Titles to start with 'Radio Modeller' 'Radio Controlled Models and Electronics' [there are a number of other more recent publications but these two were the trend setters over the period of interest ca 1980-1995]

'ffkiwi'

combatpigg

My Feedback: (3)

Alpbak, I suggest a 6 inch chord wing because you can buy balsa in that width, actual scale would be more like 7 inches. Also, the nose of your .15 powered plane will most likely need to be slightly longer because a .15 is proportionately lighter...[if you are good at math, you can probably figure out exactly how much to compensate]. I also think a full depth spruce spar is needed to about 2/3 span on each wing panel. Added coolness is the V-tail, it gives a plain looking plane a lot of "pizzazz" .
The CVA is such a great engine, you really have to try hard to blow one up.

alpbak

CP,
I'm planning to make a foam wing covered with balsa and 2 carbon fiber strips thru the wing. So a 7 inch chord should not be a problem. What do you think? V-tail looks cool, right, I might do that.

combatpigg

My Feedback: (3)

That sounds like a good plan. Remember that you can't scale down air molecules, so the smaller the racer, the thinner the wing needs to be. I think you want the wing to be between 3/8"-1/2" thick. I don't believe laying carbon strips top and bottom will prevent a wing collapse, you will still need something strong to prevent compression failure.