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"Cox Tee Dee .010"



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What engine should I use?

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What engine should I use?

Post  Oldenginerod on Mon Aug 15, 2016 3:12 am

I was given both of these models quite a while back.  
They both seem to be in pretty reasonable condition, and the fellow who gave them to me said that he had taught his kids to fly on them many years before.  He is now involved in SAM and flies Old Time R/C these days.  He seemed a little vague, but thought that he'd scratch-built them from plans from Hearns Hobbies, one of the largest and longest surviving hobby shops in Melbourne AU. I'd say they were built late 60s or 70s. He couldn't recall what engines had been fitted.
The one on the right has tissue covering and the one on the left has plastic film.  There were a couple of punctures in the tissue which I have patched, one just near the leadout.  
The red film is quite good.  It uses tissue for the sides of the turtledeck and the tissue covered one uses mylar? (we used to call it celluloid).  Figure that out??  Both have red tissue covering the vertical stab.  You may notice the red one has an extra rib in the inboard wing, making it about 2" longer.

The tissue covered one measures 24" span & the other 26".  A 7" chord gives them 140 sq" & 160 sq" respectively.  Weight is 170 grams & 190 grams. That's 6oz & 6.7oz.   They look to have home made aluminium bellcranks, with soldered fixtures.

The tissue covered one is probably a little fragile to fly but I would still like to install a period-correct engine as it displays nicely.  The other one I might try to fly, so need to choose an engine which will suit the size & weight.  I have sat a couple of engines in the noses but all seem to make them nose heavy, so I need something light.  The tissue one I had thought a Cub .099 may look about right, but still seems too heavy.  That's not an issue with this one, but the other will need to balance right.  I can't think of an engine that will suit for the size of the plane and the lightness required.  The bearers are quite wide and something like a Cub .074 or even a Tee Dee .051 are too narrow.  The mounting screws are right back close to the firewall already, so I can't mount rearwards.  A Gilbert (I'll get one in the air one day Laughing ) has to mount well forward due to the rear induction.  I have a number of Enya .09s available but they're pretty heavy & probably have more power than needed.
Happy to hear your thoughts on engine choice.

Rod.
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Re: What engine should I use?

Post  KariFS on Mon Aug 15, 2016 5:08 am

Could you measure the spacing of the mounting screws?

Not sure which engines were popular in your area at the time but your comment about Enya .09s got me thinking, how about a "small-block" Enya, like the .049-II? It weighs 2 oz according to the brochure and has a front venturi. The 06 is considerably heavier, 2.9, nearly the same as .08 and .10.

I don't have a .049-II to compare but it looks a bit bulkier in the pics than a Tee Dee.
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Re: What engine should I use?

Post  rsv1cox on Mon Aug 15, 2016 7:01 am

I'm with kari on this Rod, and with you being an Enya man also.

My Dumas Scout with similar stat's as yours (25 1/2 span 5 1/4 chord) came win an Enya .06. Something similar should work as they can be either beam or radial mounted.

I must say though that your two planes came a bit more together than did my Scout. Smile I really like those designs, and the bell crank is marvelous. Wonder why the pin on the pivot?

https://www.coxengineforum.com/t9468-big-box-arrives



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Re: What engine should I use?

Post  Oldenginerod on Mon Aug 15, 2016 7:05 am

I'm hoping to use an engine I already have.  Out of 120 or so I hoped I had something suitable.
The .09 is my smallest Enya.  I'm not sure that an .049 will perform quite well enough, that's why I included the dimensions & weight etc.  I don't understand the science so well to be able to calculate the best choice.  I think I recall that the .099 OK Cub has about the right mounting spacings & they are fairly light in comparison with others of that size.  Just that the one I fly probably really needs to be muffled.  Unfortuantely that means more weight.  Cub .074 and Tee Dee .051 are too narrow, but same issue with the muffler.  Gilbert 7 has the rear venturi so hangs too far forward.  
I guess my best chance is the Enya .09 as it's the smallest engine I have that can be muffled.  I just might have to add tail weight.
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Re: What engine should I use?

Post  rsv1cox on Mon Aug 15, 2016 7:57 am

Rod if you have one of the early 3001 Enya .09's use that. It would probably be period correct and the weight difference between it and the later .09's is remarkable. 3.74 oz against 2.98.







I will check my Cubs for comparison.

Bob

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Re: What engine should I use?

Post  roddie on Mon Aug 15, 2016 11:08 am

Here's a lighter-weight candidate.. period-correct too.


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Re: What engine should I use?

Post  roddie on Mon Aug 15, 2016 1:00 pm

or maybe a Fox "Rocket" .09? I don't have one of those to measure for you.. but if you scale this article attached from Model Aircraft magazine.. it shows the dimensions full-size.






both of my posts are of American engine examples... but they might have been popular "down under" in the 1960's.

Check out this RC Universe thread by "Dan Vincent" on the McCoy .098 glow/diesel. George (CEF-gcb) made some comments.. great reading!

McCoy .098 engines
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Re: What engine should I use?

Post  roddie on Mon Aug 15, 2016 1:45 pm

Actually.. the lighter-finish model (that you plan on displaying..) looks like it may have had a diesel engine on it.. from the dark stains in the wood-beams. (I love the red wooden wheels!!)
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Re: What engine should I use?

Post  ian1954 on Mon Aug 15, 2016 3:36 pm

A PAW 100 or an OS engine - the OSMG9510.

http://www.osengines.com/motors/motors/motor-specifications.pdf


Then again, I thought you had a Taipan 1cc diesel - or I imagined it!
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Re: What engine should I use?

Post  Oldenginerod on Mon Aug 15, 2016 5:26 pm

ian1954 wrote:A PAW 100 or an OS engine - the OSMG9510.

http://www.osengines.com/motors/motors/motor-specifications.pdf


Then again, I thought you had a Taipan 1cc diesel - or I imagined it!

Thanks everyone for your suggestions. I really just wanted to find out if the .09 size was the best choice considering the size & weight of the aircraft. I had a similar size plane as a kid which had a Mills .75 diesel, but it would only circulate slowly with its nose in the air.

Yes Ian, I have a Taipan 1cc as well as a good 1.5cc diesel.  I also have a Frog Vibramatic, Kumar K 1.5 and a Silver Swallow 1.5.
While any of these would probably be suitable choices, I didn't want to go down the diesel line due to difficulty obtaining fuel.  Having said that, I will ignore your link to the OS electric motors.  Not an option  Mad

Bob, I only have the Enya Mk3 & Mk4, being the heavier option you show.

Roddie, no McCoy available but I do have a couple of the Fox .09s, but again, the rear induction puts the engine forward the same as a Gilbert. Also, the Fox is pretty anaemic and may only be suitable for the display model.  One of them has had the fuel tank cut off, so it can mount closer to the firewall, with some minor carving needed for the venturi.  I also have an early OS Pet-II which looks like it may be pretty light, but is also rather worn.

Looks like I will just have to dummy-balance the plane & weigh all my engines to see what will work.  Maybe a little carving & re-balncing required, but I really didn't want to spoil this gentleman's good building work of decades ago.  I'd suggest I will stick to my initial gut feeling and screw the OK Cub .099 (one of several) to the non-flyer.  I might even use one on the flyer & find a nice remote place to fly the noisy beast.

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Re: What engine should I use?

Post  Ken Cook on Mon Aug 15, 2016 9:09 pm

If they were mine, I would make an aluminum plate that utilizes the existing mount holes and I would cut it and re drill it for the TD. The Enya weighs as much as almost 2 TD's. Those designs share a similarity to the Sterling Viper with the diamond airfoil. That style wing needs speed to work properly. The Fox .09 is good for flying the box it came in and probably not much more. Unfortunately, the TD is non muffled, but of your engine choices I feel it would suffice the best due to weight and size and wouldn't need ounces of tail weight to balance it.
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Re: What engine should I use?

Post  rsv1cox on Tue Aug 16, 2016 5:06 pm

Checked my OK's weights Rod, Not much of an improvement over anything suggested.

.99 and .149





I always liked this style.



I have ran most of mine. I found them to start easy and run well. Don't turn the turns maybe and I'm not sure of the durability but they are not the trash some may think.



I run them, clean and oil well and bag them. Some day I will build a model around one with the attached tank.

Bob




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Re: What engine should I use?

Post  Cribbs74 on Tue Aug 16, 2016 8:44 pm

I am going to agree with Ken on this one. The TD would be your best choice. If you have to run a muffler then switch to a non SPI cylinder. If you want to run a hard tank then use a medallion carb body. Heck, you could even try a Medallion and play around with combos and see what runs better for you.

All the proposed engines are either too heavy or too sluggish for those models. A Norvel .049-.061 would probably be perfect if you had one.

Ron
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Re: What engine should I use?

Post  Oldenginerod on Tue Aug 16, 2016 9:23 pm

rsv1cox wrote:Checked my OK's weights Rod,  Not much of an improvement over anything suggested.

.99 and .149

Bob

I beg to differ.  Looks to me like the Cub .099 has a significant weight advantage over all the others shown.  I know they're no powerhouse, but the ones I have run fine & I'm sure they would do the job adequately.  Just that they're so darn loud Shocked
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Re: What engine should I use?

Post  rsv1cox on Wed Aug 17, 2016 6:58 am

I was thinking the TD that Ken and Ron suggested but that requires mods that you don't want to do, same for the Gilberts although I know your itching to use one of those.  Me too, but with all that stuff hanging out it's not an easy adaptation.  

That .099 is surprisingly light though.  Is there a fuel tank installed in either model?  

Bob
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Re: What engine should I use?

Post  Oldenginerod on Wed Aug 17, 2016 7:42 am

rsv1cox wrote:I was thinking the TD that Ken and Ron suggested but that requires mods that you don't want to do, same for the Gilberts although I know your itching to use one of those.  Me too, but with all that stuff hanging out it's not an easy adaptation.  

That .099 is surprisingly light though.  Is there a fuel tank installed in either model?  

Bob
Yes, both models have hard tanks.  They are internal so I can't judge what size they are without filling with a measuring syringe.
I think I'll have to try to balence them up with weights in the nose, measure the weight & then compare that to the engines I have.
At least it makes for an interesting exercise.
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Re: What engine should I use?

Post  706jim on Wed Aug 17, 2016 2:26 pm

roddie wrote:or maybe a Fox "Rocket" .09? I don't have one of those to measure for you.. but if you scale this article attached from Model Aircraft magazine.. it shows the dimensions full-size.






both of my posts are of American engine examples... but they might have been popular "down under" in the 1960's.

Check out this RC Universe thread by "Dan Vincent" on the McCoy .098 glow/diesel. George (CEF-gcb) made some comments.. great reading!

McCoy .098 engines

My very first engine! (er.."motor" sorry Duke). As stated in the review, it did start quite easily and lasted quite some time before losing compression; certainly a lot longer than a later Cub 0.049A that wore out in an afternoon.

The actual engine didn't look too much like the artist's rendition in MAN, but could be polished up with a bit of work.

The "integral" fuel tank wasn't nearly as eloquent as one on a Cox reedie and would have been difficult to seal with the included backplate and cork gasket.
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Re: What engine should I use?

Post  roddie on Wed Aug 17, 2016 7:34 pm

706jim wrote:
roddie wrote:or maybe a Fox "Rocket" .09? I don't have one of those to measure for you.. but if you scale this article attached from Model Aircraft magazine.. it shows the dimensions full-size.






both of my posts are of American engine examples... but they might have been popular "down under" in the 1960's.

Check out this RC Universe thread by "Dan Vincent" on the McCoy .098 glow/diesel. George (CEF-gcb) made some comments.. great reading!

McCoy .098 engines

My very first engine! (er.."motor" sorry Duke). As stated in the review, it did start quite easily and lasted quite some time before losing compression; certainly a lot longer than a later Cub 0.049A that wore out in an afternoon.

The actual engine didn't look too much like the artist's rendition in MAN, but could be polished up with a bit of work.

The "integral" fuel tank wasn't nearly as eloquent as one on a Cox reedie and would have been difficult to seal with the included backplate and cork gasket.

Wouldn't it be fun, to find an old runner.. and fire it up on the bench!
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