Down or no down (trust)

[Albatross]

I have been reading through most built reviews.
I also have downloaded the manuals of several ARF.

They even provide templates to drill the engine holes where the stands offs will be anchored.
Most of the ARF manufacturers already provide a built-in right trust but not down trust.

However seems that none of the ARF vendors seems to take care of this set up.
If during the trimming process you realize that you need to add some down trust or by the same token additional right trust, the anchor holes are already drilled.
Adding shims will do the job , however the prop hub will most likely be off.
Besides the cosmetic aspect, as the spinner back plate will not longer match the cowl exit.

Anyhow, the point is that ARF vendors & apparently ARF builders seems to take little care about down trust.

Am I missing something here?

[Dan Baker]

Yes, affraid you are. Question: how do you know that you will need down thrust on your ARF before the first fight? Some planes require up thrust as a trim adjustment... Actually, the amount of right thrust varies with the engine size and prop size choosen by the end user.

[Albatross]

Good question.
How does that the ARF vendor know that they are supplying correct right trust for my engine-airplane combo?
Evidently the assume a standard engine (DL) & standard prop.
They are saving some time for me, no complaint.

The fact of including a template leaves you with the false impression that a standard ARF built does no need to go through the trimming process.
Install your engine, servos plug you batteries and go flying.

The message would be:
As much as possible , trim your airplanes

[f5air]

after years and hundren of people buyin venderos ARF with no complain...i think they already know if is necessary or not put trust there. Thats why they spent hundred of greens and time on R&D.

[Albatross]

If the customer of those ARF vendors are using the same standard engines/props they have tested, perhaps your airplane will come along in the same bull park without doing any change, nor adding any down or up trust.
However for those like me, that don´t necessarly go with the standard engine/prop they had in mind when the ARF prototype was tested, the actual scenario might be differnt.
I guess is matter if deciding what you will be doing with your ARF: precision flight, 3D or general use airplane. This will dictate how far you want to go on fine tune your engine trust and the rest of the critical varaibles: CG, control surface mixing , etc

[classclown]

	Quote: Originally Posted by Albatross
	I have been reading through most built reviews. I also have downloaded the manuals of several ARF. They even provide templates to drill the engine holes where the stands offs will be anchored. Most of the ARF manufacturers already provide a built-in right trust but not down trust. However seems that none of the ARF vendors seems to take care of this set up. If during the trimming process you realize that you need to add some down trust or by the same token additional right trust, the anchor holes are already drilled. Adding shims will do the job , however the prop hub will most likely be off. Besides the cosmetic aspect, as the spinner back plate will not longer match the cowl exit. Anyhow, the point is that ARF vendors & apparently ARF builders seems to take little care about down trust. Am I missing something here?

They usually recommend a particular engine and use that as a model in the build. If you choose a motor that they did not use in their build and calculations, you are on your own as to figuring out a way to make your choice work. Has this hobby gotten so fickle, that some people expect everything be done for them? How long have you been in this hobby?!?

[astrohog]

Yes, I agree with Classclown! I guess Albatross should build a kit and forget about the ARF's!

It's like putting a small block in a Datsun and then complaining that it handles like crap!

Astrohog

[classclown]

	Quote: Originally Posted by astrohog
	Yes, I agree with Classclown! I guess Albatross should build a kit and forget about the ARF's! It's like putting a small block in a Datsun and then complaining that it handles like crap! Astrohog

Or, do some research and properly set up the suspension to get the thing to handle better. Or, choose a motor like the old Buick 215. If your not familiar with it, its a small 3.5 liter aluminum block V8. 200 hp stock, but if you do it right, you can get 300 to 500hp if properly done, with everyday reliability. I helped my dad, let me rephrase that, my dad helped me yank out a stock 4 cylinder iron block out of a 69 MGB roadster, we swapped in a 350hp 215, coupled to a 5 speed Worldclass tranny. Talk about a gokart with license plates. The V8 weighs 40lbs less than the original motor. I have one more of those blocks sitting in the garage. Funny that you mentioned a Datsun. Am thinking of finding an old 240Z to restore with an engine swap.

[astrohog]

I might have used a bad analogy! I am familiar with the Buick engine, and it is a light, powerful piece! I've seen it in many an import (even Porsche 914's!). I have a 1971 240 and have a 1981 280Z turbo motor that I plan to build and swap someday, until then I really enjoy tooling around with the stock motor!

Now, back to our regularly scheduled program!

Astro

[classclown]

Sweet!!! Another one would be a 944, alot of those with blown motors around here.

[Albatross]

	Quote: Originally Posted by classclown
	They usually recommend a particular engine and use that as a model in the build. If you choose a motor that they did not use in their build and calculations, you are on your own as to figuring out a way to make your choice work. Has this hobby gotten so fickle, that some people expect everything be done for them? How long have you been in this hobby?!?

Just to clarify, I started getting involved in this hobby when almost everyone used to build its own airplane.
The ARFs where not so popular nor appreciated by the RC community.

	Quote:
	Yes, I agree with Classclown! I guess Albatross should build a kit and forget about the ARF's! It's like putting a small block in a Datsun and then complaining that it handles like crap! Astrohog

There are not too many airplane kits out there to our disposal as we used to have.

Even the threads in this forum and other ones were mostly addressing airplane building, covering, gluing techniques, etc.

Let’s talk about cars

[classclown]

	Quote: Originally Posted by Albatross
	Just to clarify, I started getting involved in this hobby when almost everyone used to build its own airplane. The ARFs where not so popular nor appreciated by the RC community. There are not too many airplane kits out there to our disposal as we used to have. Even the threads in this forum and other ones were mostly addressing airplane building, covering, gluing techniques, etc. Let’s talk about cars

I don't get it. What were you complaining about then? You are not the only one who remembers the days of true model building. I love building too. But these days, I and many others just don't have the time to build from scratch, or a kit. Thank god for ARF kits. When you buy a quality arf kit, you are not just getting a quality kit, you are also buying time. Time not wasted on trying to figure out wether your thrust line will be right or wrong, etc. Hell, I even go as far as cutting out wood, just to make the plane even lighter, but thats my choice. I have 3 kits that I don't have the time to build, I would rather fly. And what is so wrong about talking about cars on a dying thread? Hit the field, get some flying in, you'll thank me later.

[2walla]

I think that you give most kit as well as arf manufacturers-too much credit for design. Airplanes design is not rocket science. Draw it up pretty, put some right thrust in it and send it out the door..

[astrohog]

	Quote: Originally Posted by 2walla
	I think that you give most kit as well as arf manufacturers-too much credit for design. Airplanes design is not rocket science. Draw it up pretty, put some right thrust in it and send it out the door..

I am sure this is the case with many of the ARF's out there today, but certainly not all of them!!

Astro

[Albatross]

	Quote: Originally Posted by classclown
	I don't get it. What were you complaining about then? You are not the only one who remembers the days of true model building. I love building too. But these days, I and many others just don't have the time to build from scratch, or a kit. Thank god for ARF kits. When you buy a quality arf kit, you are not just getting a quality kit, you are also buying time. Time not wasted on trying to figure out wether your thrust line will be right or wrong, etc. Hell, I even go as far as cutting out wood, just to make the plane even lighter, but thats my choice. I have 3 kits that I don't have the time to build, I would rather fly. And what is so wrong about talking about cars on a dying thread? Hit the field, get some flying in, you'll thank me later.

I may not explain quit well, my point is that in just about all the threads dedicated to analyze the science of building an ARF few touch the trust lines and talk about airplane trimming process.

I am not asking to set up for me a firewall with down trust in the ARF.
Sorry I did not make this clear at the beginning.

I also love flying and afford the time to build an airplane would be a chore, although I have tackled 27% projects, proudly I won a price in my club for best scale airplane.

My airplane won while being next to other nice airplanes.
The hard work was recognized or at least was more often seen in our clubs.

I really was disappointed when the causal visitors always asked my, what ARF is that thing?

Real airplane building was also a large achievement not too long ago.

Another reason why we prefer ARF is not just the time.
Cost wise, building an airplane from kit is more expensive. However kits vs. ARF is another topic.

All I can say is that kit building is gone for good, I am sorry again.
I don’t love ARF I just take what we have in the market, as I still love this hobby despite the ARF era.