Tipsy Junior AUW?

[Matt Carlton]

Hello, 

 

I just got hold of a bunch of plans and I'm rather taken with PM's little Tipsy Junior (the 1/6 scale one) and I'm contemplating swapping the electric setup from my "Amelia (47" span, 2.75lb) into it and I was pondering whether it will be sufficient as I don't think the Tipsy would need much more than 80W/lb for scalish performance. 

That setup runs an 11x5.5 prop at 320W on 3S. 

What was the AUW of the Tipsy? I can't imagine it being much more than 3lb or so? 

 

Thanks

 

Matt

[Peter Miller]

I will go and look at the original article later (after I recover from the mornings grocery shopping)

[Matt Carlton]

Ouch, I feel your pain, my company has been, erm "requested" for the weekly shop this afternoon. Usually I do it online, but apparently it will do me good to get out of the house for something other than work or flying. Who knew?? 

 

 

[kc]

If the model was for i.c. then an electric version could probably be built somewhat lighter.   Not much need to worry about vibration so perhaps leave out or reduce size of any ply doubler?

[Geoff S]

I've done a few glow/electric conversions and it's difficult to reduce the flying weight even though the motor/esc/battery combination can be lighter than the glow equivalent.  Whatever power source you use the model still has to balance in the same place and all the potential weight saving is already in front of the CoG (or well forward, at least).  That means reducing tail weight to compensate and that isn't always easy.

 

The 'secret' is usually to get the LiPo as far forward as possible - under the motor if there's room.

[Peter Miller]

2 hours ago, Matt Carlton said:

Ouch, I feel your pain, my company has been, erm "requested" for the weekly shop this afternoon. Usually I do it online, but apparently it will do me good to get out of the house for something other than work or flying. Who knew?? 

 

 

I always do my own shopping but I also have to do my next door neighbour's too.  She has a son who lives just down the road but he couldn't even find the bread counter in Waitrose.

 

I found the Tipsy Junior article but the data page was missing. I would say that it will not exceed 4 lbs, probably between 3 1/2 and 4 lbs.

[Matt Carlton]

1 hour ago, Geoff S said:

That means reducing tail weight to compensate and that isn't always easy.

 

That's true, although in this case, the tail surfaces are solid 1/4" sheet, so I could replace them with a 1/16" sheet core with ribs either side or a trad. framework. 

 

I think that even nudging 4lbs would be doable on 320W, that's still 80W/lb and that's adequate. I suspect that scale pootling would still be about half throttle. 

 

 

[Peter Miller]

12 minutes ago, Matt Carlton said:

 

That's true, although in this case, the tail surfaces are solid 1/4" sheet, so I could replace them with a 1/16" sheet core with ribs either side or a trad. framework. 

 

I think that even nudging 4lbs would be doable on 320W, that's still 80W/lb and that's adequate. I suspect that scale pootling would still be about half throttle. 

 

 

That would be soft sheet

[Matt Carlton]

This is true, I am guilty of having not read the plan properly. I apologise. 

[kc]

As Geoff suggested - it might be possible to get the Lipo right at the front under the motor on models like this with high thrustline.  That together with a nicely selected light piece of balsa for the tail parts should help get the CG right without lead.

Some electric models are being built at extremely low weights - you could get some ideas by looking at Andy Gates thread on building a Magister and also by looking at his other models on the link there.   There seems to be much scope for weight reduction in electric models.

 

Edited February 16, 2022 by kc

[Matt Carlton]

Absolutely, I am surprised at the weights we can build to when we get rid of heavy doublers, bearers and other vibration mitigating structures.

 

My latest OD spans 50" and looks a bit like a 1930s racer/sportster yet came in at 36oz (sans motor and lipo). 

 

That said, as an every day club model, we need a bit of robustness to cope with hangar rash, rough grass runways, windy, rain, dogs, small children, car doors etc etc! 

 

 

[Denis Watkins]

4 hours ago, Peter Miller said:

 

 

I found the Tipsy Junior article but the data page was missing. I would say that it will not exceed 4 lbs, probably between 3 1/2 and 4 lbs.

 

It is here

https://www.modelflying.co.uk/tipsy-junior

 

DATAFILE
Name: Tipsy Junior
Model type: Semi-scale light aircraft
Designer: Peter Miller
Fuselage length: 36.5''
Wingspan: 44''
Wing area: 462 sq. in.
All-up weight: 59.5oz
Wing loading: 18oz / sq. ft.
Rec’d engine range: .19 - .25 two-stroke,
.26 - .30 four-stroke
Control functions: Aileron, elevator, throttle and rudder

[Peter Miller]

Ah! Good! My forgetery was right!!!

[Frank Skilbeck]

Not sure if this is any help, but the club was recently gifted one of these, it had last flown some 20 years ago, the engine  Enya 35 two stroke was completely gummed solid and it had really old Sanwa servos, I've re-engined it with a Saito 40 and fitted more modern standard size servos, flies really well on this combo. For info the Saito is turning an 11 x 5 prop at around 10,000 rpm I wouldn't say it was over powered, but I think the one I've got weighs around 2 kg, so a bit on the heavy side.

[kc]

Curiously this plan does not appear to be listed by Sarik for some reason - perhaps it was just a free plan and never issued with a plan number.    Do we know the month it was published in RCME?   It does not seem to be Jan 2011 when the forum article was added.

The larger Phillip Kent version is listed by Sarik.

[Peter Miller]

March 2005

[Peter Miller]

It might be listed under their "Unclassified" list.  I found my Lake LA-4 amphibian under that classification.

The LAKE was an early control line model

 

[Matt Carlton]

There are quite a lot lurking in Sarik's "as yet unclassified" list it seems. 

 

I'm quite taken with a lot of the "goodyear-esque" plans such as Bootlace and The Minnow at the moment I must admit. 

 

 

 

[Peter Miller]

I love the small air racers.  I have books of 3 views with pictures.  Have done quite a few of them and "based on" such as Bootlace

[Matt Carlton]

3 views with pictures you say Peter? ?

 

I'm rather taken with the LS Special I built from your plan, Tequila Sunrise is up next I think, but that size, around 36" span or whatever it is, seems perfect for tossing in the car. 

 

 

[Peter Miller]

The books are  "Goodyear and Formula One Aircraft Vol 1 1947 to 1967"  and Volume 2 1967 to 1995 by Robert S. Hirsch.

146 3 views with 6 photos per aircraft. in each book.

 

Tequila Sunrise has been built in several sizes by other people and my MIss LIzzy is very close to the original

[Matt Carlton]

Thankyou very much Peter, I'll keep my eyes open, they sound like an absolute treasure trove. 

 

 

 

[Peter Miller]

Amazzon have a seller with one Vol  2 in the USA £32 plus postage.  Vol 1 is on Ebay at £21.  Now these may seem expensive...they are worth it. Don't forget, A simple one sheet plan  costs £14 these days!!!

[Matt Carlton]

That seems reasonable to me considering the work that went into them. I much prefer something I can  hold in my hands and annoy my wife my reading in bed with a pen and a pad of paper! 

[Frank Skilbeck]

22 hours ago, Frank Skilbeck said:

Not sure if this is any help, but the club was recently gifted one of these, it had last flown some 20 years ago, the engine  Enya 35 two stroke was completely gummed solid and it had really old Sanwa servos, I've re-engined it with a Saito 40 and fitted more modern standard size servos, flies really well on this combo. For info the Saito is turning an 11 x 5 prop at around 10,000 rpm I wouldn't say it was over powered, but I think the one I've got weighs around 2 kg, so a bit on the heavy side.

Oops, sorry guys, just checked the one we acquired and it's around 52" wingspan so a bit bigger than the one being discussed.