Re: [RCSE] Servo Pop out report
OK fellows, cool off, I started this epoxy vs tray war with my question about removing the servos the first owner installed in my Hera. Using the busted wings I tried several of the methods mentioned. 1) Heating with the blow dryer to soften the epoxy- I heated the skin from the opposite side for about 2 minutes and tried to slowly pull the servo out- No Luck. No damage to the wing surface but it did not soften the epoxy. Perhaps if I heated it more? Somehow it sticks in my head that softening the epoxy would increase its' stickiness. Chilling it and then beating on it might actually work better but I didn't try this because I was too lazy to run upstairs for some ice. 2) Banging on the servo from the top side of the wing dented the wing surface and did not release the servo epoxy bond. 3) Flexing the wing skin did nothing. except to make rather disconcerting crunchy noises from the skin. 4) grabbing and twisting with needle nose pliers- I could not get a good purchase on the servo due to the position of the servo off center to the hole. The only grip surface I could get a bite on was the base of the servo arm and the servo's mounting bracket. Broke the bracket off, servo still in. No Damage to wing. 5) Wedging something thin like a spatula between the servo case and the epoxy/ micro balloon. I really could not get it to separate easily and was afraid that too much pressure might result in a slip and skin puncture. 6) Putting a screw driver upside the servo at about a 45 deg angle and popping it (medium) with light hammer. servo didn't budge. I did not try a blow perpendicular to the servo case because I would have had to cut a hole in the root to insert a tapping rod and did not want to compromise this area. HOWEVER!! I then grabbed the servo with the needle nose and twisted and she popped out clean. NO damage to the wing. No epoxy on the servo case. Popping the servo a few times must have loosened the epoxy bond. Its true, Epoxy does not chemically bond to servo cases. The adhesion is purely mechanical. (as a dentist I know a bit about bonds and adhesion- we have to get things to bond on teeth in a wet environment, with lots of shear forces and thermal cycling too.) Roughing the servo case will increase the retention. CA DOES chemically bond to the case so if you put it back in with CA it might be harder to remove the second time but you might be able to use Debonder then. It should not attack the glassed underside of the skin. (BTW, I found out the hard way that debonder will loosen the bond between Silicone (Goop) and fiberglass) Certainly going to the trouble to make a mounting bracket give one faster access and more predictable removal without the anxiety of splitting a wing skin, But it does add weight and wood brackets can fail too. It also occurred to me that if you use shrink-wrap on the servo before gluing, the servo could slip and move a slight bit inside the shrink-wrap. and you have to heat that sucker up quite a bit to shrink the wrap. So what's the right way to mount a servo? Anyway that works for you, as long as you know how you are going to remove it without damaging the wing. I personally like the Voltz Wingmaxx plastic brackets that I put in my Spectre 2M. Dave Malone RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
[RCSE] spar structures questions
Jon Stone writes (Re: Allegro spar at CRRC):
What drives the value of sigma (design cap stress)? The reason I ask, is
that this is the only "variable" driving the equation for tip-deflection.
And I do not know what parameters define the value of sigma.
sigma is simply the stress the carbon fiber can withstand.
The appropriate value depends on the quality of the layup
and whether the cap can buckle or not. The numbers I used
were large for wet layup carbon, but still somewhat conservative
for prepreg carbon which cannot buckle. It is difficult to
predict the allowable sigma for structures which MIGHT buckle.
Specimen testing to failure is usually required.
Furthermore, what parameters define your values for sheer stress (tau) and
core stress (sig_C). I would like to use heavier balsa (say 8 lb) for the
shear web. Is tau the same as Shear Modulus?
The web's shear modulus (usual symbol is G) is not an issue in most
spars.
What matters is the max shear stress tau ("parallelogramming" stress)
and the compressive stress sig_C (vertical stress). These two
stresses depend on how the spar is set up. The max tau and max sigma
of balsa scale pretty linearly with density.
In the Allegro spar, the shear is taken up entirely by the half of the
skin fibers which are under tension, and the associated vertical
compression
is taken up almost entirely by the endgrain balsa core.
So the core stresses are as given in the article:
tau_C = 0
sig_C = tau As / h w
If there is no skin, then
tau_C = S / h w
sig_C = 0
This is more difficult, since the max tau of balsa is only
about 1/5 of its max sigma, and the spar may also be subject
to peel failure at the core/cap bond. This is why I used a spar skin.
But I have used this second system in my follow-up Allegro-Lite
glider to appear at CRRC soon. The core takes all the shear load.
Peel is prevented by a Kevlar tow wrap. Not as weight-efficient,
but it's very compatible with built-up balsa/Monokote structure.
One gent I've talked to used .086" x 1/2" wide carbon spar caps for his
3-meter glider. The thickness tapered to .040. He did not use any shear
web at all. He stated that if the caps were strong (thick) enough, that no
appreciable shear stress was transmitted to the foam core.
Not true. Whatever is between the caps takes the same total shear load
S.
What the caps look like is immaterial. The only way to isolate
the core from shear stress is to use wing skins with huge shear
stiffness
all around. Picture the Allegro spar skin blown up chordwise
into an airfoil shape. But the shear has to go all the way around the
airfoil instead of directly though the thickness, so it's not an
efficient use of shear material, though.
The size of the caps does affect their buckling tendency, which
is a separate issue -- you can have either shear failure of
the core or spar shear skin, or buckling failure of the caps.
The Allegro spar is aimed at dealing with both of these efficiently.
If you don't use a separate web, then you need
1) sufficiently thick sparcaps so they don't buckle with only
the soft foam restraining them. This favors narrow and thick sparcaps
(for a given cap X-sectional area).
2) sufficient other "shear stuff" between the caps to take the total S.
Normally the bit of foam between the caps cannot take the
required tau_C value as computed above. I think blue foam
has a max tau of 20 psi or so. However, the total S load
can be spread over a wider chordwise extent by using +/-45 skins
which are sufficiently stiff in shear (G * skin_thickness is adequate).
Sort of a compromise between the core-only and skin-only shear transfer.
This may require Kevlar or carbon skin, I don't know for sure.
And if the skin is required to transfer the shear from the
cap to the core, it too can buckle with 45 deg wrinkles.
It gets complicated.
Tom Kiesling's private Mantis planes use massive 1" x 0.125"
caps in the center, with 45 deg Kevlar skins and no web
(that's what I gathered from chatting --- corrections welcome).
So it can be made to work, but it's very tough to predict
the max loads without testing, and peel failure from defects
is always a concern. One reason I went to the Allegro
spar system is that it's sorta idiot-proof. Predictable
by analysis, tolerant of defects, and it cannot peel.
--
- Mark Drela
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Re: [RCSE] Fun1=Blazer=NSP Victor?
Or something brooding and ominous, like "Vendetta" or "Valkyrie" (sp? it's Friday and I'm lazy...". Cheers, Adam From: "John B" [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: Re: [RCSE] Fun1=Blazer=NSP Victor? Date: Fri, 29 Sep 2000 09:24:05 PDT How 'bout: Tsunami The name implies power and destruction (of competitors) - and it's got that funny T at the beginning. ]You are correct and I forgot! Need a new name. Best name conTest gets ]$50.00 ]credit with NSP! ] ][EMAIL PROTECTED] wrote: ] ] Sal wrote: In the meantime we have come out with ] the Filip slope at a great price and will shortly reveal two new ]molded ] 60" slope sailplanes. One is called the Fury and the ] other the Storm. ] ] Oh great, another sailplane called the STORM! ] I own the Slegers 2M Storm... about 3-5 years old design, still on ]Ed's web ] site! It is a great first full house TD ship with sloping potential. ] ] Bruce in Vancouver, WA ] ]-- ]Sal DeFrancesco ]Northeast Sailplane Products ]948 Hercules Dr. Suite 12 ]Colchester, Vt. 05446 ]802-655-7700 ] ]Website: http://www.nesail.com ] ] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
Re: [RCSE] Fun1=Blazer=NSP Victor?
Or something simple, like "Scrote". Jim At 02:17 PM 9/29/2000, Adam Till wrote: Or something brooding and ominous, like "Vendetta" or "Valkyrie" (sp? it's Friday and I'm lazy...". Cheers, Adam From: "John B" [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: Re: [RCSE] Fun1=Blazer=NSP Victor? Date: Fri, 29 Sep 2000 09:24:05 PDT How 'bout: Tsunami The name implies power and destruction (of competitors) - and it's got that funny T at the beginning. ]You are correct and I forgot! Need a new name. Best name conTest gets ]$50.00 ]credit with NSP! ] ][EMAIL PROTECTED] wrote: ] ] Sal wrote: In the meantime we have come out with ] the Filip slope at a great price and will shortly reveal two new ]molded ] 60" slope sailplanes. One is called the Fury and the ] other the Storm. ] ] Oh great, another sailplane called the STORM! ] I own the Slegers 2M Storm... about 3-5 years old design, still on ]Ed's web ] site! It is a great first full house TD ship with sloping potential. ] ] Bruce in Vancouver, WA ] ]-- ]Sal DeFrancesco ]Northeast Sailplane Products ]948 Hercules Dr. Suite 12 ]Colchester, Vt. 05446 ]802-655-7700 ] ]Website: http://www.nesail.com ] ] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Jim Downers Grove, IL Member of Chicago SOAR club ICQ 6997780R/C Soaring Page at http://www.mcs.net/~bacuslab/soaring.html RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
Re: [RCSE] Fun1=Blazer=NSP Victor?
Three more because Sal didn't say we couldn't offer more than one... "Howlocity" "NewToy" "Excuse" Jim At 02:17 PM 9/29/2000, Adam Till wrote: Or something brooding and ominous, like "Vendetta" or "Valkyrie" (sp? it's Friday and I'm lazy...". Cheers, Adam From: "John B" [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: Re: [RCSE] Fun1=Blazer=NSP Victor? Date: Fri, 29 Sep 2000 09:24:05 PDT How 'bout: Tsunami The name implies power and destruction (of competitors) - and it's got that funny T at the beginning. ]You are correct and I forgot! Need a new name. Best name conTest gets ]$50.00 ]credit with NSP! ] ][EMAIL PROTECTED] wrote: ] ] Sal wrote: In the meantime we have come out with ] the Filip slope at a great price and will shortly reveal two new ]molded ] 60" slope sailplanes. One is called the Fury and the ] other the Storm. ] ] Oh great, another sailplane called the STORM! ] I own the Slegers 2M Storm... about 3-5 years old design, still on ]Ed's web ] site! It is a great first full house TD ship with sloping potential. ] ] Bruce in Vancouver, WA ] ]-- ]Sal DeFrancesco ]Northeast Sailplane Products ]948 Hercules Dr. Suite 12 ]Colchester, Vt. 05446 ]802-655-7700 ] ]Website: http://www.nesail.com ] ] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Jim Downers Grove, IL Member of Chicago SOAR club ICQ 6997780R/C Soaring Page at http://www.mcs.net/~bacuslab/soaring.html RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
Re: [RCSE] Dunk Tank Vote
Daryl is all wet Perkins. I bid $10.00 to get first crack :) Smooth Sailing, Karlton Spindle http://www.MultiplexRC.com Team Multiplex World F3J Champions USA F3B Champion USA F3J Champion USA Open Class Champion USA 1:5 Scale R/C car Touring Champions USA 1:5 Scale R/C car GT Champions - Original Message - From: [EMAIL PROTECTED] To: "Bill Swingle" [EMAIL PROTECTED] Cc: "RCSE Soaring" [EMAIL PROTECTED] Sent: Friday, September 29, 2000 1:09 PM Subject: Re: [RCSE] Dunk Tank Vote Personally, I wanna dunk Joe. ;-) Daryl - not gonna get wet - Perkins Bill Swingle wrote: It appears that there will be a dunk tank at Visalia. Rumor is that it will be a fund raising event for the US F3B team. GREAT idea Phil! You da man! Who would you like to dunk I'm now accepting VOTES. Who do ya wanna dunk? Send me your votes, I'll tally the results and get them to Ed Hipp. He'll then assemble a lynch mob and toss the "winner" in the tank. (assuming he wants to participate in this silliness) Bill Swingle [EMAIL PROTECTED] Janesville, CA RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
[RCSE] Which word don't you understand?
For all of you who DON'T think using epoxy to mount servos is a bad idea and have RAGGED on me because I do, please take the time to read what I actually said. QUOTE: It's stupid to mount servos permanently with epoxy so that they cannot be removed to replace a broken arm or gears. WHICH WORD DON'T YOU UNDERSTAND? If you feel that I called you STUPID because you do this, well, that's your interpretation. It might just be the case. You'll know for sure if you can't remove the servo without damaging the wing, won't you? If you can, then It's a moot point, isn't it? If you still don't agree or understand, go back and read this message from the beginning. (as many times as it takes) RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
Re: [RCSE] Which word don't you understand?
Stupid is probably a good name, if memory serves the definition is that the person has been informed and does not use the info. I also fly RC powered combat and when I start building the model I will mount a small piece of balsa to the appropriate side of the servo and then can contour the piece of balsa to the side of the fuse and CA that on very quickly when it is time to install. The loads are fairly large (proportional to the servo size) and are applied very quickly, with no servo mount failures in the combat, HLG and 2M Take care Jim RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
Re: [RCSE] Which word don't you understand?
To clarify the mounting: I mount the servo to the balsa with silicone glue so that it can be removed and replaced if need be. Take care Jim RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
[RCSE] Alcyone 3M Instructions
Does anyone have or know where I can get a soft copy of the Alcyone 3M instructions? My set came without page seven. I tried comparing the hard copy to the soft copy on the Northeast Sailplane site but they are different. Thanks, Kevin B. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
Re: [RCSE] Dunk Tank Vote
Problem is, with guys like Joe and DP, they don't sink. What the hell's the fun in watching somebody bob up and down ON the water? If there's thermal activity in that water, you bet yer bippie that Joe will be ridin it and laughin his arse off. You can change the medium, but the result will be the same. Heh :) JS From: [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Bill Swingle [EMAIL PROTECTED] CC: RCSE Soaring [EMAIL PROTECTED] Subject: Re: [RCSE] Dunk Tank Vote Date: Fri, 29 Sep 2000 13:09:21 -0700 Personally, I wanna dunk Joe. ;-) Daryl - not gonna get wet - Perkins Bill Swingle wrote: It appears that there will be a dunk tank at Visalia. Rumor is that it will be a fund raising event for the US F3B team. GREAT idea Phil! You da man! Who would you like to dunk I'm now accepting VOTES. Who do ya wanna dunk? Send me your votes, I'll tally the results and get them to Ed Hipp. He'll then assemble a lynch mob and toss the "winner" in the tank. (assuming he wants to participate in this silliness) Bill Swingle [EMAIL PROTECTED] Janesville, CA RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
