Ray Malmstrom's Push-up! - RC Groups
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Sep 13, 2017, 04:40 PM
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Guizzo 17's Avatar
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Ray Malmstrom's Push-up!


Hi all! I'm back presenting you an electric R/C conversion of Raymond Malmstom's Push-up model.
I was able to decrypt the plan I found on Outerzone and trace my own with all the changes needed for the conversion, including minor changes to suit my building style and simplify construction.

The model is quite simple and I don't think it'll take much time to complete, however I need to find a proper crew for this plane but, unluckily, I was not capable to find the Malmstrom's instructions describing how to make them and I'm still loosing time sailing on the net to find ideas!

I intend to use what I have available, so the motor is a Turnigy 1810 3500 with an Hobby King 10 A regulator fed by a 2S 500 mA/h pack and two BMS 303 Blue Bird servos. No decision yet on the receiver.

I aim for a model under 220 gram and a maximum wing load of 25 gram/dm2.

I'm going to build the tail first and since L.E. and T.E. are not straight, I prefer them laminated. The same applies for the wing.
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Sep 14, 2017, 12:32 PM
Hey, watch this!
Raymond-leflyr's Avatar
One of my favorites of his. Can't wait to see her finished - and videos too.
Sep 14, 2017, 01:24 PM
SB-28 UK Display Pilot
GeeW's Avatar
I hope that suitable crew will be installed in the cockpit?
Sep 14, 2017, 04:35 PM
Registered User
Guizzo 17's Avatar
Quote:
Originally Posted by Raymond-leflyr
... Can't wait to see her finished ...
Me too!

Quote:
Originally Posted by GeeW
I hope that suitable crew will be installed in the cockpit?
It's a MUST!
The problem is that, at the moment, I do not have a clue where I may find it!!
Sep 14, 2017, 05:27 PM
AndyKunz's Avatar
Maxim. Victoria's Secret.
Sep 15, 2017, 04:47 PM
Registered User
Guizzo 17's Avatar
Quote:
Originally Posted by AndyKunz
Maxim. Victoria's Secret.
Thanks a lot for the suggestion Andy, I examined with attention and interest all the file and photos of the candidates but, although they may know how to properly handle a stick and be confident with Push-up, mine is a vintage model which may better suit an elder crew! Anyway I appreciated your contribute!

Some work done. Sadly I'm not able to stay seated for more than a couple of hours. Then I need to to do something else, like walking, flying or whatever!

Malmstrom used to like thick flat bottom profiles but a modern electric conversion requires increased performances, so I think a 10% thickness is a better choice and I'll use the same airfoil for tail and wing. Nothing exotic though, just my trusty TLAR airfoil!

As you may see, the ruddervator I have traced is roughly 1/3 of the V tail.

In order to simplify the building, I'm going to assemble the tail-plane mount directly to the tail, deviating slightly again from the original plan!
Sep 15, 2017, 07:42 PM
AndyKunz's Avatar
When it's electric instead of Push Up it might be Underwire.



Andy
Sep 18, 2017, 04:58 PM
Registered User
Guizzo 17's Avatar
Quote:
Originally Posted by AndyKunz
When it's electric instead of Push Up it might be Underwire.

Andy


I went ahead just a little completing the two parts of the taileron and sanding to shape leading and trailing edge.
It took a while to do, but I like the final result.
The two parts of the taileron are joined through the tailplane mount which, practically, is a thick rib with side faces cut to 45 degrees.
Parts are stuck together with a dihedral brace amid the spars.
Sep 19, 2017, 04:12 AM
Registered User
I think Ray used the same type of crew in his "Mandy" which was an unpublished C/L model from 1949. I can't remember where, but I'm sure I've read somewhere how to make those crew members, using Ping-Pong balls for heads
Sep 20, 2017, 04:11 PM
Registered User
Guizzo 17's Avatar
Thanks T. S. This is a picture that may help me to make the two figures. I'm using small foam balls but my first trials are not encouraging at the moment!

This is the firs time that I use quite extensively cyanoacrilate.
I have always used it sparingly because too difficult to release small drops of glue and the bottle tip clogs too easily and in the wrong moment even using the extension tips and I was never able to use all the glue contained in the bottle.
What works for me now is the small applicator tube in the picture. I'm able to release tiny quantity of glue in small areas, the tip do not clogs easily and I don't need to strive my fingers to squeeze the glue out. Compared with a 30 gram dispenser, this 3 gram tube seems expensive, but I don't waste glue anymore and it runs a long way resulting a bargain in the end.
I wander if any of you have tried it....

The ruddervator structure is completed with hinges. Weight is 18 gram.
Next comes the wing.
Sep 22, 2017, 05:08 AM
Registered User
rchopper56's Avatar
Found the Pattex Super Glue on Amazon but will not deliver to USA.

Gene
Sep 24, 2017, 10:03 AM
Edubarca
Edubarca's Avatar
Ray was a super genius and such a nice person. I never met him but we had correspondence (paper with stamp variety!!!!!) He was one of my mentors during my early aeromodelling stages. I miss him!!!!!
Sep 24, 2017, 04:49 PM
Registered User
Guizzo 17's Avatar
Quote:
Originally Posted by rchopper56
Found the Pattex Super Glue on Amazon but will not deliver to USA.
Gene
forgive me but I could not answer you earlier!
In Europe the P. glue is sold in blisters with two tubes and costs a couple of Euro. Although not available in your country, I would give a try to any other brand, providing it is a similar 3 gram tube dispenser.
What I mostly appreciate in fact, is the dispenser itself. I guess you may find something similar for a couple of bucks and in case you don't like it, you have not vested a fortune!

Quote:
Originally Posted by Edubarca
Ray was a super genius and such a nice person. I never met him but we had correspondence (paper with stamp variety!!!!!) He was one of my mentors during my early aeromodelling stages. I miss him!!!!!
I'm sure you are right Edubarca. Just looking at his photos you may guess what his temper was!


I worked a bit on the wing these last days.
The original spar was one inch high, cut from 1/8 balsa sheet, flat on the top and with a double dihedral on the bottom.
Since, as already said, I reduced the thickness of the ribs, I had to change the spar making it as an I beam and flat on the bottom. The small flat central section mimics the tail and is made from solid balsa block.
Sep 28, 2017, 05:00 PM
Registered User
Guizzo 17's Avatar
I made something these last days, I completed and covered the tail and the wing is almost finished. Weight of the parts are a bit more than what I had supposed but acceptable. Instead of my usual Esaky over Mylar covering, this time I used modelspan over mylar since the latter has brighter color which do not fades as Esaky does, however it's heavier and absorbs more paint to seal.
These are the weights of the two parts:

Tailplane structure 18g; finished 25g.
wing structure 23g; finished 35g

Tomorrow I'll post pictures of the completed wing.


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