DA 170 shakes

[IMAC FANATIC]

Thank you Vern, I believe Dave and I have installed just about everything you have to offer installed on our planes , truly outstanding products! really good info and also true info. I appreciate when someone can skillfully apply full scale knowledge to models, assuming you have some aviation background in there also,im lucky enough to have a friend with an aeronautical engineering degree in my corner to help me somewhat understand it all. In my Jtec kit , he sketched out a " Z" frame , like you mentioned but top and bottom stringers following the diagonal, motor box to wing tube and then to the tail plate , like many full scale designs use, to dampen stress, twist and vibration, only added 3.2 oz weight using 3/8 stringers with .007 carbon lamimated to diagonals and carbon fiber balsa laminate triangle caps to tie to formers. I cant describe just how torsionally strong it is, should get every available ounce of torque from the motor, DA 150L on re3's, And yes, installing all the gear around it is a bear,and it added weight but I figured.. im building ONE for years and not ONE a year, wish I could ! Btw im using the zero degree motor mount and backing plate on that one also.

Im sure someone will offer a detailed and scientific observation of yourwell stated and simple to grasp theory, but thats what the internet and forums are for ... I guess. Im sure glad you posted, thank you



Point is, any time and work , monies , materials spent on quieting vibration is worth the effort, unless you like replacing your airframe every few seasons. most people just ignore it as.. its supposed to make those sounds.. shake like that etc.. youll be surprised at just how smooth , quiet and strong it is when your done.

 

[orthobird]

this is a dalton i am building, in this picture, you can see the cross bracing...

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[orthobird]

here is firewall pinned...

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[2robinhood]

My Sukhoi, DA-170, and RE3's.

About the same.

 

[mndless]

IMAC FANATIC;19988 wrote: Forgot to mention.. have you ever seen the chip hyde soft mounts? Like to have one someday, heavy but makes good sense.you tube em', kinda cool.

Are Merle and Chip related? Wondered about that. The soft mounts are made by Merle... just ordered a soft mount for a 170 (same mounting dimensions as the 150)... they are not inexpensive.. the weight is reported at 10 oz, not too terrible and 3/4" thick.



Should have it in a couple weeks, will post pics when it gets here.



PM me if you want Merles email address, no website to order or anything...

 

[mbacosa]

I believe that Merle is Chips dad.

 

[IMAC FANATIC]

As far as I know Merle is his dad, not sure though. Id like to see a thread on that mount, please keep me posted. but ouch 10oz. Thats alot of tail weight to compensate for something already balanced and flying.

 

[jamesrxx951]

Thanks for all the help and ideas guys. I tried my 29/12N 3 blade today and it's hard to say but I think it may have been a little smoother. After the contest this weekend I think I will do some of the cross bracing as described and even see what I can do with the engine box. One thing I had to do with my AW 150CC 300 was to fully sheet the ailerons because they were weak and killing my aileron servos from tip flutter. The center bushing in the upper case was worn in less than 50 flights. After the aileron mod and nothing else they lasted 150 flights on that plane and 100 on this plane with no issues at all. Might even add a 3rd servo to each wing half to spread the load. Every I run this engine (today was no exception) I get excited on how it sounds and pulls.

 

[Vern.Smith]

I did a little (very little :smile-new: ) thinking about getting the engines cyclical vibration to the airplane's center of mass. Here is a couple of illustrations of a simple devise that can be fabricated from aluminum 1" diameter .049 wall tubing and some 1/16 sheet 6061 aluminum. It should weigh 4 to 5 ounces. The blue plate fits against the back of the firewall and also becomes the nut plate for the engine through bolts. The green stubs are riv-nuts which are threaded 1/4 x 20 to accept the engine bolts. The purple is the thin wall aluminum tube and the orange colored aluminum beam aligns with the wing tube and attaches to the plates the wing tube is bonded to. If the guy who designed the fuse knew his business the two main hard points behind the fire wall should be the landing gear attachment points and the wing tube attachment points. We are using the wing tube attachment points to absorb the engines power pulses. The aluminum beam between the wing tube attachment points gives the wood attachment points a five to one lever advantage over the aluminum tube which is desirable because the aluminum tube is much much stronger than the wood.



I realize this will not make tank location much fun but I don't think it will add any more weight than all the wood bracing and extra strength going into the engine boxes currently weight. It will do a lot better job than all the diagonal cross bracing could do and it will keep the engine boxes together a lot longer.



Vern Smith

White Rose Engineering




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[jamesrxx951]

 I thought I would update this thread. At NCFR finals over the weekend I looked a few planes that also had the 170. Most of them shook pretty similar to mine. There were 2 other Sukhoi's there with DA150s and a Dalton with the new DA150L. I was rather impressed with the power of the 150's. So for now I plan on some light beefing up of the plane as others suggested and maybe add a 3rd servo to each wing half to try and spread the vibration load to more servos. Im still not sure what the future holds for the 170 but as of now I plan on working through it because there is no doubt that this engine starts every time, uber reliable, and makes great power. Since I do not have the disposable capitol (especially because we are saving $$$ for building our new home) for a DA200L mag case, im going to push through with this route.