IMO, it's because

(a) Dave Brown is a Moron. Thank god he's gone. FWIW, Dave Mathewson has indicated that for topics like the speed limit he'd listen to his experts - such as the JPO - rather than be pig-headed like Brown was.

(b) The JPO was only ever interested in pushing for HEAVIER models, not faster ones.

Gordon

So, if I understand this correctly: Experimental class for turbines now starts above 75 lbs dry weight, not 55 lbs. So a 60 lb A-10 is no longer required to have an experimental rating?

David S

That is the way i read it-"Under 75#s fueled" So for your Hog subtract 12 pounds for fuel leaves you at 63#s dry so you should be golden Big Dave. For your plane you got a 8 pound dry increase. ( or just dont fill it all the way up Scotty

According to my reading, a 60 pound (dry) A-10 was not legal before and now it is.

Even now, it would have to be an experimental. It still cannot weight more that 75 pounds wet. The difference is now it does not have to weight less than (or equal to) 55 pounds dry.

David,

Matt is correct. The rule change is *only* to the Experimental Rules. The following rule in the *general AMA Safety Code* is unchanged:

The maximum takeoff weight of a model aircraft, including fuel, is 55 pounds, except for those flown under the AMA Experimental Aircraft Rules.


Also, this rule in the turbine safety code is also unchanged:

For Turbojets and Turbofans single engine static thrust shall not exceed 45 pounds; multiple
engine static thrust shall not exceed 50 pounds combined.



The change is that *if* you go above 55 lbs *with fuel* you are now in the experimental class and your wet weight limit is now 75 lbs, there is *no* specific dry limit, and thrust can now go past 45 lbs (50 lbs for a twin) until it gets to 1:1.

If you go into the experimental class, you have to get your aircraft inspected by an experimental class inspector and signed off. In doing so, you no longer have to calculate the required servo power, you simply have to meet or exceed the manufacturer's recommendations.

As I said earlier, I don't see many (or any?) jet guys on the experimental inspector list for California so some of you guys (Matt, David?) need to fill out the paperwork and get on the list for your jet buddies...

Bob

My A-10 is already certified "Experimental Class". Billy Edwards is a certified Inspector and signed me off during our "HawgFest" weekend last August.

Now if I have this right: A fully fueled 55lb F-15 is:

1. Not experimental
2. Limited to 45lbs thrust as a single
3. Limited to 50lbs thrust as a twin

A fully fueled 56-75lb F-15 is:

1. Must be certified "Experimental"
2. Limited to 1:1 thrust to weight, single or twin powered no matter

David S

That looks right to me.

The only clarification I would seek is whether the thrust restrictions in the experimental case are installed or uninstalled.

I just got a letter from Ilona Maine informing me that I need to "re-certify" my A-10. I can't find the requirement to re-certify in the
AMA experimental documents (520-A/B/C), other than the "Permit expires date" on the Permit to Fly list. Looks like the date is always 1 year after initial certification. There is a list of reasons to "suspend" the Permit to Fly, such as after a major modification or crash, and if the airplane "has not been flown for a period of twelve months". Seems funny to have that last one if you have to re-certify after 1 year anyway.

FYI for when you "re-certify", the Permit to Fly form is new as of January 2009. Similar to the old one but with a few additional fields.

Looks like David and Joe are good until August but Billy is due in Feb.

Craig

Just to satisfy the curiosity of a nosy European, under what category (if any) in the USA could one fly the likes of Steve's 14% scale DH Comet (weight 120 lb wet, pair of P-120 engines) or Dave's Vulcan (150 lb wet, pair of 36 lb Merlins)?
In other words, is the 75 lb (jet) 100 lb (prop) an absolute top limit or just the start of "Experimental".?

It Britain, anything over 20 kg (44 pounds) needs to be inspected and certified similar to your experimental class.

We discussed that earlier in the thread. Keith indicated that it was unclear and would likely be up to the inspector. I would be inclined to consider it as installed thrust and to allow another 2 to 3 lbs of thrust at the turbine to account for pipe losses...

Bob

David, this is exactly correct.

If I understand the question correctly, it will be up to the inspector to use judgement if the installation would reduce thrust (e.g. bifurcated pipe). The intent of the regulation as I would interpret it is actual installed thrust. The rule is silent as to this point.

75 turbine and 100 prop (both wet) are the maximum weights you can fly in the US if you, your club or your site owner want the protection of AMA insurance.

This will probably be looked at in the future, but not until the FAA committee on Small UAVs has finished it's rulemaking deliberations this spring. This would also need to be a point of negotiation with the AMA's insurance carrier.

Then why not have the inspector measure installed thrust?

EDIT: Thanks in advance and sorry if I am missing something obvious.

I think that most inspectors would be open to measuring installed thrust, but some of us don't have a proper way to do that... I'd use one if the owner had one available though.

Bob

I agree with Bob.

What are the requirements and process to get "certified" as an "experimental inspector"?

Fill out an application, make a "resume" of your model aircraft experience, get three references from other AMA members, and read the rules and take a short "quiz"...

Its all here: http://www.modelaircraft.org/files/520-A.pdf

Piece of cake!

Bob

How does AMA know the weight? Especially if they have to pay a claim from an accedent which may only be a pile of smoldering jet? This whole weight thingy seems very subjective to me. Moreover, who is running around with a scale checking jet weights?

In practice, the issue would not come up unless there were a claim. If it were a very large liability claim, the insurance investigators would work to recreate the weight of the airplane. If the conclusion was there was no way it was under 55 pounds, they deny the claim and its up to you to prove otherwise.